BACKGROUND:The conventional tests for the diagnosis of early stage pancreatic carcinoma are not acceptable.This metaanalysis is to evaluate the accuracy of K-ras mutation for the diagnosis of pancreatic carcinoma.DATA...BACKGROUND:The conventional tests for the diagnosis of early stage pancreatic carcinoma are not acceptable.This metaanalysis is to evaluate the accuracy of K-ras mutation for the diagnosis of pancreatic carcinoma.DATA SOURCES:A systemic search of all relevant literature was performed in Web of Science,EMBASE,Cochrane Database,and MEDLINE(PubMed as the search engine) prior to June 1,2011.Thirty-four studies fulfilled the inclusion criteria and data were pooled for analysis.RESULTS:The pooled estimates for K-ras mutation in diagnosis of pancreatic carcinoma were as follows:sensitivity 0.68(95% CI:0.66-0.71),specificity 0.87(95% CI:0.85-0.88),positive likelihood ratio 4.54(95% CI:3.47-5.94),negative likelihood ratio 0.37(95% CI:0.30-0.44) and diagnostic odds ratio 14.90(95% CI:10.02-22.15).Summary receiver operating characteristic analysis demonstrated that the maximum joint sensitivity and specificity was 0.79,and the overall area under the curve was 0.86.CONCLUSIONS:Diagnostic accuracy of K-ras mutation was not superior to that of conventional tests.Therefore,K-ras mutation analysis alone is not recommended for the diagnosis of pancreatic carcinoma.展开更多
Purpose: K-ras mutations were reported to be in 40% - 60% of patients with sporadic colorectal cancers (CRCs). HER-2/neu oncogene that is important in breast carcinoma was reported in CRCs in several studies. The aims...Purpose: K-ras mutations were reported to be in 40% - 60% of patients with sporadic colorectal cancers (CRCs). HER-2/neu oncogene that is important in breast carcinoma was reported in CRCs in several studies. The aims of our study are to determine;the frequency of K-ras mutation in CRC and positivity of HER-2/neu, the relation between K-ras mutation and HER-2/neu positivity, and also the relation between clinicopathological findings with K-ras mutation and HER-2/neu expression. Methods: Total of 35 colon resection specimen from patients without distant metastasis who were operated due to colorectal adenocarcinoma were included in the study. The sections were examined with light microscopy. Vascular and perineural invasions and pericolonic tumor deposits (PCTD) were investigated. HER-2/neu was applied immunohistochemically. DNA sample obtained from tumor paraffin block was screened for presence of 20 mutations in K-ras gene-codon 12, 13, 61 by AutoGenomics and Infinity Analyzer. Results: K-ras gene mutation was detected in 14 of 35 patients (40%). HER-2/neu positivity was detected in 7 cases (28.57%). There was not any significant correlation between HER-2/neu positivity, K-ras gene mutation and clinicopathological findings. There was direct correlation between PCTD and vascular invasion. Conclusions: There was not correlation between K-ras mutation and clinicopathological findings similar to several other studies. The relation between HER-2/neu expression and clinicopathological findings was not found.展开更多
AIM:To investigate the functions of promoter hypermethylation of O6-methylguanine-DNA methyltransferase(MGMT)gene in colorectal tumorigenesis and progression.METHODS:The promoter hypermethylation of MGMT gene was dete...AIM:To investigate the functions of promoter hypermethylation of O6-methylguanine-DNA methyltransferase(MGMT)gene in colorectal tumorigenesis and progression.METHODS:The promoter hypermethylation of MGMT gene was detected in 27 sporadic colorectal adenomas,62 sporadic colorectal carcinomas and 20 normal colorectal mucosa tissues by methylation-specific PCR.At the same time,the expression of MGMT protein was carried out in the same samples using immunohistochemistry.Mutantallele-specific amplification was used to detect K-rasG to A point mutation in codon 12.RESULTS:None of the normal colorectal mucosa tissues showed methylated bands.Promoter hypermethylation was detected in 40.7%(11 of 27)of adenomas and 43.5%(27 of 62)of carcinomas.MGMT proteins were expressed in nucleus and cytoplasm of normal colorectal mucosa tissues.Loss of MGMT expression was found in 22.2%(6 of 27)of adenomas and 45.2%(28 of 62)of carcinomas.The difference between them was significant(P=0.041).In the 6 adenomas and 28 carcinomas losing MGMT expression,5 and 24 cases presented methylation,respectively(P=0.027,P<0.001).Thirteen of the 19 colorectal tumors with K-rasG to A point mutation in codon 12 had methylated MGMT(P=0.011).The frequencies of K-rasG to A point mutation were 35.3%(12 of 34)and 12.7%(7 of 55)in tumors losing MGMT expression and with normal expression,respectively.CONCLUSION:Promoter hypermethylation and loss of expression of MGMT gene were common events in colorectal tumorigenesis,and loss of expression of MGMT occurs more frequently in carcinomas than in adenomas in sporadic patients.Hypermethylation of the CpG island of MGMT gene was associated with loss of MGMT expression and K-ras G to A point mutation in colorectal tumor.The frequency of K-ras G to A point mutation was increased in tumors losing MGMT expression.It suggests that epigenetic inactivation of MGMT plays an important role in colorectal neoplasia.展开更多
Background Difficulties persist in differentiating pancreatic ductal adenocarcinomas （PDAC） from pancreatic inflammatory masses （PIM）. Auxiliary diagnostic techniques which enhance the endoscopic ultrasound-guided...Background Difficulties persist in differentiating pancreatic ductal adenocarcinomas （PDAC） from pancreatic inflammatory masses （PIM）. Auxiliary diagnostic techniques which enhance the endoscopic ultrasound-guided fine-needle aspiration （EUS-FNA） diagnostic yield have been attempted, for example, K-ras mutation analysis. We aimed to evaluate the accuracy of K-ras mutation analysis combined with EUS-FNA for the differential diagnosis of PDAC and PIM by pooling data of existing trials. Methods We systematically searched the Medline, PubMed, Web of Science, Embase, and Cochrane Central Trials databases for relevant published studies. Meta-analysis was performed. Pooling was conducted in fixed-effect model or random-effect model. Results In total eight studies, with 696 cases of PDAC and 138 cases of PIM, met our inclusion criteria. The pooled sensitivity, specificity, positive likely ratio and negative likely ratio of K-ras mutation analysis combined with cytopathology for diagnosis of PDAC versus PIM were 90%, 95%, 13.45, and 0.13, respectively. Especially, among total 123 patients whose EUS-FNA results were inconclusive or negative, fifty-nine had K-ras mutations and were finally diagnosed with PDAC （48%, 59/123）. Publication bias was not present. Conclusions Combining K-ras mutation analysis with routine cytology moderately improves the ability of EUS-FNA to differentially diagnose between PDAC and PIM, especially for patients with suspected PDAC yet inconclusive EUS-FNA findings, and may prove to be a valuable supplemental method to EUS-FNA.展开更多
AIM:To identify and assess mutations in the K-ras and BRAF genes in a cohort of Chinese patients with colorectal cancer (CRC) for their association with various clinicopathological parameters and prognosis.METHODS:Gen...AIM:To identify and assess mutations in the K-ras and BRAF genes in a cohort of Chinese patients with colorectal cancer (CRC) for their association with various clinicopathological parameters and prognosis.METHODS:Genomic DNA was isolated from frozen tissues.Pyrosequencing analysis was conducted to detect mutations in the K-ras (codons 12,13,and 61) and BRAF genes (codon 600).Statistical analysis was carried out using SPSS-15.0 software.RESULTS:Among the 118 colorectal cancer patients,we detected 41 (34.7%) mutations in the K-ras gene.Mutation frequencies at codon 12 and codon 13 were 23.7% (28/118) and 10.2% (12/118),respectively.Only one patient harbored a point mutation at codon 61 (0.8%,1/118).Gender was the only factor that showed an obvious relationship with K-ras gene mutation (female 44.7% vs male 28.2%,P=0.037).Other clinicopathological features,such as age,location of the tumor,tumor differentiation,Tumor,Node and Metastases classification,and the Union for International Cancer Control staging,showed no positive relationship with K-ras gene mutations.No significant correlation was observed between the presence of K-ras mutations (codons 12,13,and 61) and the survival of the patients.BRAF mutations were rare,and only two patients (1.7%) harbored a detectable mutation at codon 600.CONCLUSION:K-ras gene mutation is a common event in our 118 Chinese CRC patients,with an obvious relationship with gender.However,it seems not to be an independent prognostic factor in CRC patients.The BRAF gene is rarely mutated in Chinese CRC patients.展开更多
AIM:To study the genetic alteration in ACF and to define the possibility that ACF may be a very early morphological lesion with molecular changes,and to explore the relationship between ACF and colorectal adenoma even...AIM:To study the genetic alteration in ACF and to define the possibility that ACF may be a very early morphological lesion with molecular changes,and to explore the relationship between ACF and colorectal adenoma even carcinoma. METHODS: DNA from 35 CRC, 15 adenomas, 34 ACF and 10 normal mucus was isolated by means of microdissection. Direct gene sequencing of K-ras gene including codon 12, 13 and 61 as well as the mutation cluster region (MCR) of APC gene was performed. RESULTS: K-ras gene mutation frequency in ACF, adenoma and carcinoma was 17.6% (6/34), 13.3% (2/15), and 14.3% (5/35) respectively, showing no difference (P 】 0.05) in K-ras gene mutation among three pathologic procedures. The K-ras gene mutation in adenoma, carcinoma and 4 ACF restricted in codon 12 (GGT GAT), but the other 2 mutations from ACF located in codon 13 (GGC GAC). K-ras gene mutation was found more frequently in older patients and patients with polypoid cancer. No mutation in codon 61 was found in the three tissue types. Mutation rate of APC gene in adenoma and carcinoma was 22.9% (8/35) and 26.7% (4/15), which was higher than ACF (2.9%) (P 【0.05). APC gene mutation in carcinoma was not correlated with age of patients, location, size and differentiation of tumor. CONCLUSION: ACF might be a very early morphological lesion in the tumorogenesis of colorectal tumor. The morphological feature and gene mutation status was different in ACF and adenoma. ACF is possibly putative microadenoma that might be the precursor of adenoma. In addition, the development of a subgroup of colorectal carcinomas might undergo a way of normal epithelium ACF carcinomas .展开更多
A highly sensitive electrochemiluminescence-polymerase chain reaction (ECL-PCR) method for K-ras point mutation detection is developed. Briefly, K-ras oncogene was amplified by a Ru(bpy)3(2+) (TBR)-labeled forward and...A highly sensitive electrochemiluminescence-polymerase chain reaction (ECL-PCR) method for K-ras point mutation detection is developed. Briefly, K-ras oncogene was amplified by a Ru(bpy)3(2+) (TBR)-labeled forward and a biotin-labeled reverse primer, and followed by digestion with MvaI restriction enzyme, which only cut the wild-type amplicon containing its cutting site. The digested product was then adsorbed to the streptavidin-coated microbead through the biotin label and detected by ECL assay. The experiment results showed that the different genotypes can be clearly discriminated by ECL-PCR method. It is useful in point mutation detection, due to its sensitivity, safety, and simplicity.展开更多
AIM:To summarize progress in the study of K-ras gene studies in pancreatic cancer and its potential clinical significance in screening test for early detection of pancreatic cancer,and to differentiate pancreatic canc...AIM:To summarize progress in the study of K-ras gene studies in pancreatic cancer and its potential clinical significance in screening test for early detection of pancreatic cancer,and to differentiate pancreatic cancer from chronic pancreatitis in recent decade.METHODS:Literature search (MEDLINE 1986-2003) was performed using the key words K-ras gene, pancreatic cancer, chronic pancreatitis, and diagnosis. Two kind of opposite points of view on the significance of K-ras gene in detection early pancreatic cancer and differentiation pancreatic cancer from chronic pancreatitis were investigated.The presence of a K-ras gene mutation at codon 12 has been seen in 75-100% of pancreatic cancers, and is not rare in patients with chronic pancreatitis, and represents an increased risk of developing pancreatic cancer. However,the significance of the detection of this mutation in specimens obtained by needle aspiration from pure pancreatic juice and from stools for its utilization for the detection of early pancreatic cancer, and differentiation pancreatic cancer from chronic pancreatitis remains controversial.CONCLUSION:The value of K-ras gene mutation for the detection of early pancreatic cancer and differentiation pancreatic cancer from chronic pancreatitis remains uncertains in clinical pratice. Nevertheless, K-ras mutation screening may increase the sensitivity of FNA and ERP cytology and may be useful in identifying pancreatitis patients at high risk for developing cancer, and as a adjunct with cytology to differentiate pancreatic cancer from chronic pancreatitis.展开更多
AIM: To investigate the utility of K-ras mutation analysis ofultrasound guided fine-needle aspirate biopsy of pancreaticmasses.METHODS: Sixty-six ultrasound guided fine-needle biopsieswere evaluated by cytology, histo...AIM: To investigate the utility of K-ras mutation analysis ofultrasound guided fine-needle aspirate biopsy of pancreaticmasses.METHODS: Sixty-six ultrasound guided fine-needle biopsieswere evaluated by cytology, histology and k-ras mutation.The mutation at codon 12 of the k-ras oncogene wasdetected by artificial restriction fragment lengthpolymorphisms using Bst NI approach.RESULTS: The presence of malignant cells was reported in40 of 54 pancreatic carcinomas and K-ras mutations weredetected in 45 of the 54 FNABs of pancreatic carcinomas. Thesensitivity of cytology and k-ras mutation were 74 % and 83%, respectively. The speciality of cytology and k-ras mutationwere both 100 %. The sensitivity and speciality of k-ras mutationcombined with cytology were 83 % and 100 %, respectively.CONCLUSION: High diagnostic accuracy with acceptablediscomfort of FNAB make it useful in diagnosis of pancreaticcarcinoma. Ultrasound guided fine-needle biopsy is a safeand feasible method for diagnosing pancreatic cancer.Pancreatic carcinoma has the highest K-ras mutation rateamong all solid tumors. The mutation rate of k-ras is about80-100 %. The usage of mutation of codon 12 of k-rasoncogene combined with cytology is a good alternative forevaluation of pancreatic masses.展开更多
AIM: To study the value of monitoring K-ras point mutation at codon 12 and telomerase activity in exfoliated cells obtained from pancreatic duct brushings during endoscopic retrograde cholangiopancreatography (ERCP) i...AIM: To study the value of monitoring K-ras point mutation at codon 12 and telomerase activity in exfoliated cells obtained from pancreatic duct brushings during endoscopic retrograde cholangiopancreatography (ERCP) in the diagnosis of pancreatic cancer.METHODS: Exfoliated cells obtained from pancreatic duct brushings during ERCP were examined in 27 patients: 23 with pancreatic cancers, 4 with chronic pancreatitis. K-ras point mutation was detected with the polymerase chain reaction and restriction fragment-length polymorphism(PCR-RFLP). Telomerase activity was detected by PCR and telomeric repeat amplification protocol assay (PCR-TRAP-ELISA).RESULTS: The telomerase activities in 27 patients were measured in 21 exfoliated cell samples obtained from pancreatic duct brushings. D450 value of telomerase activities in pancreatic cancer and chronic pancreatitis were 0.446+0.27 and 0.041+0.0111, respectively. Seventy-seven point eight percent (14/18) of patients with pancreatic cancer and none of the patients with chronic pancreatitis showed telomerase activity in cells collected from pancreatic duct brushings when cutoff value of telomerase activity was set at 2.0. The K-ras gene mutation rate (72.2%) in pancreatic cancer was higher than that in chronic pancreatitis (33.3%) (P<0.05). In considering of both telomerase activities and K-ras point mutation, the total positive rate was 83.3% (15/18), and the specificity was 100%.CONCLUSION: Changes of telomerase activities and K-ras point mutation at codon 12 may be an early event of malignant progression in pancreatic cancer. Detection of telomerase activity and K-ras point mutation at codon 12 may be complementary to each other, and is useful in diagnosis of pancreatic cancer.展开更多
AIM:To study the diagnostic significance of K-ras gene mutations in fecal samples from elderly patients with large intestinal cancer.METHODS: DNA was extracted in the fecal and tissue samples from 23 large intestinal ...AIM:To study the diagnostic significance of K-ras gene mutations in fecal samples from elderly patients with large intestinal cancer.METHODS: DNA was extracted in the fecal and tissue samples from 23 large intestinal cancer patients, 20 colonic adenomatoid polypus patients and 20 healthy subjects. The K-ras gene mutations at the first and second bases of codon 12 were detected by the allele specific mismatch method.RESULTS: The K-ras gene mutation was 56.52%(13/23) in the large intestinal cancer patients, which was notably higher than that in the normal subjects whose K-ras gene mutation was 5%(1/20) (x^2=12.93, P<0.001). There was no significant difference in comparison with that of colonic adenomatoid polypus patients whose K-ras gene mutation was 30%(6/12)(x^2=3.05, P>0.05). The K-ras gene mutation at the second base of codon 12 was 92.13%(12/13) in the large intestinal cancer patients. There was no significant difference between the detection rate of K-ras gene mutation in the fecal and tissue samples (X^2=9.35, P<0.01).CONCLUSION:Our results indicate that detection of the K-ras gene mutations in fecal samples provides a non-invasive diagnostic method for the elderly large intestinal cancer patients. Its significance in the early diagnosis of large intestinal cancer awaits further studies.展开更多
OBJECTIVE: To assess the diagnostic value of endoscopic pancreatic duct brushing in detecting mutation of the K-ras gene at codon 12 in cytologic specimens from patients with pancreatic cancer. METHODS: Thirty-five pa...OBJECTIVE: To assess the diagnostic value of endoscopic pancreatic duct brushing in detecting mutation of the K-ras gene at codon 12 in cytologic specimens from patients with pancreatic cancer. METHODS: Thirty-five patients treated at Changhai Hospital, Shanghai between 1999 and 2001 were enrolled. Their cells obtained by pancreatic duct brushing during endoscopic retrograde tholangiopancreatography (ERCP) were suspended with phosphate buffer solution (PBS). DNA of the cells was extracted and mutation of the K-ras gene at codon 12 detected by means of PCR-SSCP. RESULTS: The K-ras gene mutation rate of pancreatic cancer was 70%, which was higher than that of chronic pancreatitis (14%, P<0.05). K-ras gene mutation was not found in patients with pancreatic cystorcarcinoma and duodenum carcinoma. As to the location of pancreatic cancer, no significant difference was observed between the head, the body and tail. The sensitivity, specificity, accuracy of pancreatic duct brushing in detecting pancreatic cancer was 70%, 94%, and 83%, respectively. CONCLUSION: K-ras analysis of pancreatic brushing samples is helpful in the diagnosis of patients with early pancreatic cancer.展开更多
AIM: To determine bhe accuracy of p53 gene mutations predicted by overexpression of p53 protein immunohistochemically,and to investigate the co-mutation of p53 and K-ras genes in rectal cancer and its effect on promot...AIM: To determine bhe accuracy of p53 gene mutations predicted by overexpression of p53 protein immunohistochemically,and to investigate the co-mutation of p53 and K-ras genes in rectal cancer and its effect on promoting malignant biologic behaviors of tumors.METHODS: Ninety-seven specimens of rectal cancer were surgically resected in our hospital from August 1996 to October 1997. The hot mutation areas of p53 gene (in exons 5-8) and K-rasgene (in codon 5/12 and 13) were detected with polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), and overexpression of p53 protein was detected with immunohistochemistry (IHC) in the 97 specimens of rectal cancer. Correlation between gene mutations and tumor clinicopathologic factors was studied, and survival analysis was penfomed as well.RESULTS: There were 36 cases of p53 gene mutations in 61 p53 protein positive cases, and 21 cases of p53 gene non-mutation in 36 p53 protein negative cases respectively.The coincidence rate of p53 gene mutation by IHC method with PCR-SSCP method was 58.8% (57/97). The mutation rate of p53 gene was 52.6% (51/97), while K-ras gene mutation was observed in codons 12 and 13 in 61 cases with a mutation rate of 62.9% (61/97). Single gene mutation of p53 or K-raswas found in 32 cases. Both p53 and K-ras gene mutation were found in 48 cases. Statistical analysis showed that p53 and K-ras gene mutations were not related to the dinicopathologic factors, including tumor size, gross tumor type, histological dassification, differentiation, invasion to intestinal veins, lymphatics and nerves, invasive depth to.wall, lymph node metastasis, and Dukes' stages (P>0.05).The survival in patients with no gene mutation, single gene mutation and both gene mutations were similar (P>0.05).CONCLUSION: IHC has a certain false positive and false negative rate in detecting p53 gene mutations. Malignant biological behaviours of rectal cancer are not enhanced by p53 and K-rasgene mutations. Co-mutation of p53 and K-ras gene has neither synergic carcinogenesis-promoting effect,nor prognostic effect on rectal cancer.展开更多
AIM: To clarify the molecular mechanism involved in pathogenesis of colorectal cancer as well as clinical significance of genetic analysis of histological samples.
AIM:To investigate frequency and clinical significance of K-ras mutations in pancreatic diseases and to identify its diagnostic values in pancreatic carcinoma.METHODS:117 ductal lesions were identified in the availabl...AIM:To investigate frequency and clinical significance of K-ras mutations in pancreatic diseases and to identify its diagnostic values in pancreatic carcinoma.METHODS:117 ductal lesions were identified in the available sections from pancreatic resection specimens of pancreatic ductal adenocarcinoma, comprising 24 pancreatic ductal adenocarcinoma, 19 peritumoral ductal atypical hyperplasia, 58 peritumoral ductal hyperplasia and 19 normal duct at the tumor free resection margin. 24 ductal lesions were got from 24 chronic pancreatitis. DNA was extracted.Codon 12 K-ras mutations were examined using the two-step polymerase chain reaction (PCR) combined with restriction enzyme digestion,followed by nonradioisotopic single-strand conformation polymorphism (SSCP) analysis and by means of automated DNA sequencing.RESULTS: K-ras mutation rate of the pancreatic carcinoma was 79%(19/24) which was significantly higher than that in the chronic pancreatitis 33%(8/24) (P<0.01). It was also found that K-ras mutation rate was progressively increased from normal duct at the tumor flee resectbn margin, peritumoral ductal hyperplasia, peritumoral ductal atypical hyperplasia to pancreatic ductal adenocardnoma. The mutation pattern of K-ras 12 codon of chronic pancreatitis was GGT→GAT, GGT and CGT,which is identical to that in pancreatic carcinoma.CONCLUSION:K-ras mutation may play a role in the malignant transformation of pancreatic ductal cell. K-ras mutation was not specific enough to diagnose pancreatic carcinoma.展开更多
Objective:To study the role of the mutations of p53, APC and K-ras genes in 47 cases of 3 types of intestinal metaplasia (IM) of gastric mucosa. Methods:In 47 cases of IM, exons 5- 8 of p53 and exons 15 of APC were ex...Objective:To study the role of the mutations of p53, APC and K-ras genes in 47 cases of 3 types of intestinal metaplasia (IM) of gastric mucosa. Methods:In 47 cases of IM, exons 5- 8 of p53 and exons 15 of APC were examined with PCR-SSCP and codon 12 of K-ras with PCR-RFLP to detect the existence of any mutations of these structures. Results:Muta- tions of p53, APC and K-ras were found in 29.8% (14/47),6.4% (3/47) and 6.4% (3/47) respectively in our series of patients who consisted of 33 with types I and II and 14 with type III of IM. The mutation rate of p53 was far higher in patients with type III IM (57.1%,8/14) than in those with types I and II IM(18.2%,6/33)(P <0.05). Though the mutation rate of APC and K-ras was also higher in the patients with type III IM than in those with types I and II IM, it was of no statistical significance (P >0.05). In one case of type III IM, mutation of both p53 and K-ras was found. Conclusion: The molecular changes of 3 types of IM are different. The mutation of p53 may be closely related to carcinogenesis in cases of type III IM and it serve as a sign for the early diagnosis of gastric carcinoma.展开更多
Objective： To detect the style of K-ras gene point mutation in human pancreatic cancer cell line PANC-1 and decide the bp sequence of Ras target position interfered by RNA. Methods： Three kinds of special sequence p...Objective： To detect the style of K-ras gene point mutation in human pancreatic cancer cell line PANC-1 and decide the bp sequence of Ras target position interfered by RNA. Methods： Three kinds of special sequence primers （SSP） for polymerase chain reaction （PCR） with regard to the mutation styles （OAT, COT and GOT） at codon 12 of K-ras were used to study the human pancreatic cancer cell line PANC-1. The amplification products were studied with polyacrylamine gel electrophoresis to detect the style of point mutation. Results： The style of K-ras gene point mutation at codon 12 was OAT in human pancreatic cancer cell line. Conclusion： PCR-SSP is rapid, convenient and high specific. The results provide a basis for further gene therapy by RNA interference for pancreatic cancer.展开更多
To evaluate the feasibility and clinical significance of the PCR SSP technique in detecting K ras gene mutation at codon 12 in pancreatic adenocarcinoma tissues. 80 specimens of surgical resection or biopsy samples ...To evaluate the feasibility and clinical significance of the PCR SSP technique in detecting K ras gene mutation at codon 12 in pancreatic adenocarcinoma tissues. 80 specimens of surgical resection or biopsy samples were tested at our hospital from January 1994 to September 1995. Three different special sequence primers (SSP) synthesized according to mutation styles of CGT, GTT, GAT were respectively prepared. Three amplification reactions were performed for each sample. The amplification products were analyzed by conventional polyacrylamide gel electrophoresis, stained with ethidium bromide and observed under UV transillumination. Results: All of the 34 pancreatic adenocarcinoma samples had positive PCR results with the mutation rate 100%. 7 cases were CGT mutation, 18 GGT and 17 GAT mutation, in which 2 types of mutation existed in 8 cases. No mutation appeared in 13 normal pancreatic tissues, 6 insulinomas, 6 chronic pancreatitis, 5 benign pancreatic cysts, 7 bile duct carcinoma, 5 ampulla carcinoma and 4 carcinomas of duodenal papilla. Conclusion: Pancreatic adenocarcinoma is one of the commonly encounted tumors and is still very difficult to diagnose at the early stage and to distinguish from other lesions preoperatively. Our study indicates that PCR SSP is an ideal assay in comparison with other methods to detect K ras gene mutation. It is simple, rapid, specific, sensitive and easily generalized for clinical application on preoperative diagnosis.展开更多
Objective: Molecular targeted drugs have been widely used in clinical application which has successfully prolonged some patients' life. Meanwhile, molecular targeted drug therapy for esophageal cancer are attracti...Objective: Molecular targeted drugs have been widely used in clinical application which has successfully prolonged some patients' life. Meanwhile, molecular targeted drug therapy for esophageal cancer are attracting more and more attention from doctors and experts. However, little study has been done towards the effect of this approach for treating esophageal squamous cell carcinoma. This paper, therefore, intends to explore the possibilities of applying EGFR-TKI inhibitors or anti-EGFR monoclonal antibody in esophageal squamous cell carcinoma by studying the mutations of EGFR, K-ras and B-raf in the esophageal squamous cell carcinoma tissues. Methods: Thirty-five cases of resected specimens of diagnosed esophageal squamous cell carcinoma with complete clinical and pathological data from January to April 2009 were collected. Pyrophosphate was used for observing the mutations of EGFR, K-ras and B-raf in the esophageal squamous cell carcinoma tissues. Results: Examinations were undertaken respectively to the codon segment 746-754 of exon 19 in EGFR genes, codon 12 and 13 in K-ras genes as well as condon 600 in B-raf genes. No mutation was found in EGFR and B-raf genes with mutation rate 0% (0/35), all of codon 12 in K-ras genes were wild-type without any mutation, while 2 specimens of codon 13 had mutations with mutation rate of 5.71% (2/35). Conclusion: In treating esophageal squamous cell carcinoma patients, all K-ras genes are expressed as wild type due to low mutation rate; cetuximab is effective due to low mutation rate of B-raf while EGFR-TKI inhibitor will not be effective enough because of low mutation rate of EGFR genes.展开更多
OBJECTIVE To investigate gene mutations of epidermal growth factor receptor （EGFR） and K-RAS （Kirsten rat sarcoma viral oncogene） in Chinese patients with non-small cell lung cancer （NSCLC）, and study the correl...OBJECTIVE To investigate gene mutations of epidermal growth factor receptor （EGFR） and K-RAS （Kirsten rat sarcoma viral oncogene） in Chinese patients with non-small cell lung cancer （NSCLC）, and study the correlation with its protein expression and its clinical significance on gefitinib.METHODS Detect the EGFR and K-RAS gene mutations status by gene sequencing and use the method of immunohistochemistry to detect EGFR and K-RAS protein expression.RESULTS The frequency of EGFR mutations was 33%, mainly located in exon 19 and exon 21. The frequency of K-RAS mutations was 5.5%, mainly located in codon 12. There was no case which both had EGFR and K-RAS mutations, suggesting a mutually exclusive relationship between the two. EGFR mutations are more common in adenocarcinomas （particularly those with bronchioloalveolar features）, nonsmokers and females. 16% were detected EGFR positive expression and had no correlation with EGFR mutation （P 〉 0.05）, but had significant correlation with mutation in exon 19 （P 〈 0.05）. The frequency of K-RAS positive expression was 52.5% and had no correlation with K-RAS mutation （P 〉 0.05）. Twelve （8 cases were protein-negative） out of 15 gefitinib-treated NSCLC patients with disease control carry EGFR mutations.CONCLUSION EGFR protein expression has some correlation with exon 19 mutations. Combined detection of EGFR and K-RAS gene mutations can help clinicians to choose patients who may benefit from EGFR tyrosine kinase inhibitor （EGFR-TKI） and to predict the response and prognosis of gefitinib.展开更多
文摘BACKGROUND:The conventional tests for the diagnosis of early stage pancreatic carcinoma are not acceptable.This metaanalysis is to evaluate the accuracy of K-ras mutation for the diagnosis of pancreatic carcinoma.DATA SOURCES:A systemic search of all relevant literature was performed in Web of Science,EMBASE,Cochrane Database,and MEDLINE(PubMed as the search engine) prior to June 1,2011.Thirty-four studies fulfilled the inclusion criteria and data were pooled for analysis.RESULTS:The pooled estimates for K-ras mutation in diagnosis of pancreatic carcinoma were as follows:sensitivity 0.68(95% CI:0.66-0.71),specificity 0.87(95% CI:0.85-0.88),positive likelihood ratio 4.54(95% CI:3.47-5.94),negative likelihood ratio 0.37(95% CI:0.30-0.44) and diagnostic odds ratio 14.90(95% CI:10.02-22.15).Summary receiver operating characteristic analysis demonstrated that the maximum joint sensitivity and specificity was 0.79,and the overall area under the curve was 0.86.CONCLUSIONS:Diagnostic accuracy of K-ras mutation was not superior to that of conventional tests.Therefore,K-ras mutation analysis alone is not recommended for the diagnosis of pancreatic carcinoma.
文摘Purpose: K-ras mutations were reported to be in 40% - 60% of patients with sporadic colorectal cancers (CRCs). HER-2/neu oncogene that is important in breast carcinoma was reported in CRCs in several studies. The aims of our study are to determine;the frequency of K-ras mutation in CRC and positivity of HER-2/neu, the relation between K-ras mutation and HER-2/neu positivity, and also the relation between clinicopathological findings with K-ras mutation and HER-2/neu expression. Methods: Total of 35 colon resection specimen from patients without distant metastasis who were operated due to colorectal adenocarcinoma were included in the study. The sections were examined with light microscopy. Vascular and perineural invasions and pericolonic tumor deposits (PCTD) were investigated. HER-2/neu was applied immunohistochemically. DNA sample obtained from tumor paraffin block was screened for presence of 20 mutations in K-ras gene-codon 12, 13, 61 by AutoGenomics and Infinity Analyzer. Results: K-ras gene mutation was detected in 14 of 35 patients (40%). HER-2/neu positivity was detected in 7 cases (28.57%). There was not any significant correlation between HER-2/neu positivity, K-ras gene mutation and clinicopathological findings. There was direct correlation between PCTD and vascular invasion. Conclusions: There was not correlation between K-ras mutation and clinicopathological findings similar to several other studies. The relation between HER-2/neu expression and clinicopathological findings was not found.
基金Supported by the Key Technologies R&D Program of Hubei Province,No.2002AA301C84.
文摘AIM:To investigate the functions of promoter hypermethylation of O6-methylguanine-DNA methyltransferase(MGMT)gene in colorectal tumorigenesis and progression.METHODS:The promoter hypermethylation of MGMT gene was detected in 27 sporadic colorectal adenomas,62 sporadic colorectal carcinomas and 20 normal colorectal mucosa tissues by methylation-specific PCR.At the same time,the expression of MGMT protein was carried out in the same samples using immunohistochemistry.Mutantallele-specific amplification was used to detect K-rasG to A point mutation in codon 12.RESULTS:None of the normal colorectal mucosa tissues showed methylated bands.Promoter hypermethylation was detected in 40.7%(11 of 27)of adenomas and 43.5%(27 of 62)of carcinomas.MGMT proteins were expressed in nucleus and cytoplasm of normal colorectal mucosa tissues.Loss of MGMT expression was found in 22.2%(6 of 27)of adenomas and 45.2%(28 of 62)of carcinomas.The difference between them was significant(P=0.041).In the 6 adenomas and 28 carcinomas losing MGMT expression,5 and 24 cases presented methylation,respectively(P=0.027,P<0.001).Thirteen of the 19 colorectal tumors with K-rasG to A point mutation in codon 12 had methylated MGMT(P=0.011).The frequencies of K-rasG to A point mutation were 35.3%(12 of 34)and 12.7%(7 of 55)in tumors losing MGMT expression and with normal expression,respectively.CONCLUSION:Promoter hypermethylation and loss of expression of MGMT gene were common events in colorectal tumorigenesis,and loss of expression of MGMT occurs more frequently in carcinomas than in adenomas in sporadic patients.Hypermethylation of the CpG island of MGMT gene was associated with loss of MGMT expression and K-ras G to A point mutation in colorectal tumor.The frequency of K-ras G to A point mutation was increased in tumors losing MGMT expression.It suggests that epigenetic inactivation of MGMT plays an important role in colorectal neoplasia.
文摘Background Difficulties persist in differentiating pancreatic ductal adenocarcinomas （PDAC） from pancreatic inflammatory masses （PIM）. Auxiliary diagnostic techniques which enhance the endoscopic ultrasound-guided fine-needle aspiration （EUS-FNA） diagnostic yield have been attempted, for example, K-ras mutation analysis. We aimed to evaluate the accuracy of K-ras mutation analysis combined with EUS-FNA for the differential diagnosis of PDAC and PIM by pooling data of existing trials. Methods We systematically searched the Medline, PubMed, Web of Science, Embase, and Cochrane Central Trials databases for relevant published studies. Meta-analysis was performed. Pooling was conducted in fixed-effect model or random-effect model. Results In total eight studies, with 696 cases of PDAC and 138 cases of PIM, met our inclusion criteria. The pooled sensitivity, specificity, positive likely ratio and negative likely ratio of K-ras mutation analysis combined with cytopathology for diagnosis of PDAC versus PIM were 90%, 95%, 13.45, and 0.13, respectively. Especially, among total 123 patients whose EUS-FNA results were inconclusive or negative, fifty-nine had K-ras mutations and were finally diagnosed with PDAC （48%, 59/123）. Publication bias was not present. Conclusions Combining K-ras mutation analysis with routine cytology moderately improves the ability of EUS-FNA to differentially diagnose between PDAC and PIM, especially for patients with suspected PDAC yet inconclusive EUS-FNA findings, and may prove to be a valuable supplemental method to EUS-FNA.
基金Supported by The Department of Education of Zhejiang Province of China,grant No.Y200804314the Zhejiang Provincial Natural Science Foundation,grant No.R2090353+1 种基金the Department of Science and Technology of Zhejiang Province,grant No.2008C33039the Chinese Ministry of Health,grant No.N20100148
文摘AIM:To identify and assess mutations in the K-ras and BRAF genes in a cohort of Chinese patients with colorectal cancer (CRC) for their association with various clinicopathological parameters and prognosis.METHODS:Genomic DNA was isolated from frozen tissues.Pyrosequencing analysis was conducted to detect mutations in the K-ras (codons 12,13,and 61) and BRAF genes (codon 600).Statistical analysis was carried out using SPSS-15.0 software.RESULTS:Among the 118 colorectal cancer patients,we detected 41 (34.7%) mutations in the K-ras gene.Mutation frequencies at codon 12 and codon 13 were 23.7% (28/118) and 10.2% (12/118),respectively.Only one patient harbored a point mutation at codon 61 (0.8%,1/118).Gender was the only factor that showed an obvious relationship with K-ras gene mutation (female 44.7% vs male 28.2%,P=0.037).Other clinicopathological features,such as age,location of the tumor,tumor differentiation,Tumor,Node and Metastases classification,and the Union for International Cancer Control staging,showed no positive relationship with K-ras gene mutations.No significant correlation was observed between the presence of K-ras mutations (codons 12,13,and 61) and the survival of the patients.BRAF mutations were rare,and only two patients (1.7%) harbored a detectable mutation at codon 600.CONCLUSION:K-ras gene mutation is a common event in our 118 Chinese CRC patients,with an obvious relationship with gender.However,it seems not to be an independent prognostic factor in CRC patients.The BRAF gene is rarely mutated in Chinese CRC patients.
基金This subject is supported by the Fund for Returned Scientists and Scholars,[1999]363.Chinese Ministry of Education.
文摘AIM:To study the genetic alteration in ACF and to define the possibility that ACF may be a very early morphological lesion with molecular changes,and to explore the relationship between ACF and colorectal adenoma even carcinoma. METHODS: DNA from 35 CRC, 15 adenomas, 34 ACF and 10 normal mucus was isolated by means of microdissection. Direct gene sequencing of K-ras gene including codon 12, 13 and 61 as well as the mutation cluster region (MCR) of APC gene was performed. RESULTS: K-ras gene mutation frequency in ACF, adenoma and carcinoma was 17.6% (6/34), 13.3% (2/15), and 14.3% (5/35) respectively, showing no difference (P 】 0.05) in K-ras gene mutation among three pathologic procedures. The K-ras gene mutation in adenoma, carcinoma and 4 ACF restricted in codon 12 (GGT GAT), but the other 2 mutations from ACF located in codon 13 (GGC GAC). K-ras gene mutation was found more frequently in older patients and patients with polypoid cancer. No mutation in codon 61 was found in the three tissue types. Mutation rate of APC gene in adenoma and carcinoma was 22.9% (8/35) and 26.7% (4/15), which was higher than ACF (2.9%) (P 【0.05). APC gene mutation in carcinoma was not correlated with age of patients, location, size and differentiation of tumor. CONCLUSION: ACF might be a very early morphological lesion in the tumorogenesis of colorectal tumor. The morphological feature and gene mutation status was different in ACF and adenoma. ACF is possibly putative microadenoma that might be the precursor of adenoma. In addition, the development of a subgroup of colorectal carcinomas might undergo a way of normal epithelium ACF carcinomas .
文摘A highly sensitive electrochemiluminescence-polymerase chain reaction (ECL-PCR) method for K-ras point mutation detection is developed. Briefly, K-ras oncogene was amplified by a Ru(bpy)3(2+) (TBR)-labeled forward and a biotin-labeled reverse primer, and followed by digestion with MvaI restriction enzyme, which only cut the wild-type amplicon containing its cutting site. The digested product was then adsorbed to the streptavidin-coated microbead through the biotin label and detected by ECL assay. The experiment results showed that the different genotypes can be clearly discriminated by ECL-PCR method. It is useful in point mutation detection, due to its sensitivity, safety, and simplicity.
文摘AIM:To summarize progress in the study of K-ras gene studies in pancreatic cancer and its potential clinical significance in screening test for early detection of pancreatic cancer,and to differentiate pancreatic cancer from chronic pancreatitis in recent decade.METHODS:Literature search (MEDLINE 1986-2003) was performed using the key words K-ras gene, pancreatic cancer, chronic pancreatitis, and diagnosis. Two kind of opposite points of view on the significance of K-ras gene in detection early pancreatic cancer and differentiation pancreatic cancer from chronic pancreatitis were investigated.The presence of a K-ras gene mutation at codon 12 has been seen in 75-100% of pancreatic cancers, and is not rare in patients with chronic pancreatitis, and represents an increased risk of developing pancreatic cancer. However,the significance of the detection of this mutation in specimens obtained by needle aspiration from pure pancreatic juice and from stools for its utilization for the detection of early pancreatic cancer, and differentiation pancreatic cancer from chronic pancreatitis remains controversial.CONCLUSION:The value of K-ras gene mutation for the detection of early pancreatic cancer and differentiation pancreatic cancer from chronic pancreatitis remains uncertains in clinical pratice. Nevertheless, K-ras mutation screening may increase the sensitivity of FNA and ERP cytology and may be useful in identifying pancreatitis patients at high risk for developing cancer, and as a adjunct with cytology to differentiate pancreatic cancer from chronic pancreatitis.
基金Natural Scientific Foundation of Heilongjiang Province, No.97024
文摘AIM: To investigate the utility of K-ras mutation analysis ofultrasound guided fine-needle aspirate biopsy of pancreaticmasses.METHODS: Sixty-six ultrasound guided fine-needle biopsieswere evaluated by cytology, histology and k-ras mutation.The mutation at codon 12 of the k-ras oncogene wasdetected by artificial restriction fragment lengthpolymorphisms using Bst NI approach.RESULTS: The presence of malignant cells was reported in40 of 54 pancreatic carcinomas and K-ras mutations weredetected in 45 of the 54 FNABs of pancreatic carcinomas. Thesensitivity of cytology and k-ras mutation were 74 % and 83%, respectively. The speciality of cytology and k-ras mutationwere both 100 %. The sensitivity and speciality of k-ras mutationcombined with cytology were 83 % and 100 %, respectively.CONCLUSION: High diagnostic accuracy with acceptablediscomfort of FNAB make it useful in diagnosis of pancreaticcarcinoma. Ultrasound guided fine-needle biopsy is a safeand feasible method for diagnosing pancreatic cancer.Pancreatic carcinoma has the highest K-ras mutation rateamong all solid tumors. The mutation rate of k-ras is about80-100 %. The usage of mutation of codon 12 of k-rasoncogene combined with cytology is a good alternative forevaluation of pancreatic masses.
文摘AIM: To study the value of monitoring K-ras point mutation at codon 12 and telomerase activity in exfoliated cells obtained from pancreatic duct brushings during endoscopic retrograde cholangiopancreatography (ERCP) in the diagnosis of pancreatic cancer.METHODS: Exfoliated cells obtained from pancreatic duct brushings during ERCP were examined in 27 patients: 23 with pancreatic cancers, 4 with chronic pancreatitis. K-ras point mutation was detected with the polymerase chain reaction and restriction fragment-length polymorphism(PCR-RFLP). Telomerase activity was detected by PCR and telomeric repeat amplification protocol assay (PCR-TRAP-ELISA).RESULTS: The telomerase activities in 27 patients were measured in 21 exfoliated cell samples obtained from pancreatic duct brushings. D450 value of telomerase activities in pancreatic cancer and chronic pancreatitis were 0.446+0.27 and 0.041+0.0111, respectively. Seventy-seven point eight percent (14/18) of patients with pancreatic cancer and none of the patients with chronic pancreatitis showed telomerase activity in cells collected from pancreatic duct brushings when cutoff value of telomerase activity was set at 2.0. The K-ras gene mutation rate (72.2%) in pancreatic cancer was higher than that in chronic pancreatitis (33.3%) (P<0.05). In considering of both telomerase activities and K-ras point mutation, the total positive rate was 83.3% (15/18), and the specificity was 100%.CONCLUSION: Changes of telomerase activities and K-ras point mutation at codon 12 may be an early event of malignant progression in pancreatic cancer. Detection of telomerase activity and K-ras point mutation at codon 12 may be complementary to each other, and is useful in diagnosis of pancreatic cancer.
文摘AIM:To study the diagnostic significance of K-ras gene mutations in fecal samples from elderly patients with large intestinal cancer.METHODS: DNA was extracted in the fecal and tissue samples from 23 large intestinal cancer patients, 20 colonic adenomatoid polypus patients and 20 healthy subjects. The K-ras gene mutations at the first and second bases of codon 12 were detected by the allele specific mismatch method.RESULTS: The K-ras gene mutation was 56.52%(13/23) in the large intestinal cancer patients, which was notably higher than that in the normal subjects whose K-ras gene mutation was 5%(1/20) (x^2=12.93, P<0.001). There was no significant difference in comparison with that of colonic adenomatoid polypus patients whose K-ras gene mutation was 30%(6/12)(x^2=3.05, P>0.05). The K-ras gene mutation at the second base of codon 12 was 92.13%(12/13) in the large intestinal cancer patients. There was no significant difference between the detection rate of K-ras gene mutation in the fecal and tissue samples (X^2=9.35, P<0.01).CONCLUSION:Our results indicate that detection of the K-ras gene mutations in fecal samples provides a non-invasive diagnostic method for the elderly large intestinal cancer patients. Its significance in the early diagnosis of large intestinal cancer awaits further studies.
文摘OBJECTIVE: To assess the diagnostic value of endoscopic pancreatic duct brushing in detecting mutation of the K-ras gene at codon 12 in cytologic specimens from patients with pancreatic cancer. METHODS: Thirty-five patients treated at Changhai Hospital, Shanghai between 1999 and 2001 were enrolled. Their cells obtained by pancreatic duct brushing during endoscopic retrograde tholangiopancreatography (ERCP) were suspended with phosphate buffer solution (PBS). DNA of the cells was extracted and mutation of the K-ras gene at codon 12 detected by means of PCR-SSCP. RESULTS: The K-ras gene mutation rate of pancreatic cancer was 70%, which was higher than that of chronic pancreatitis (14%, P<0.05). K-ras gene mutation was not found in patients with pancreatic cystorcarcinoma and duodenum carcinoma. As to the location of pancreatic cancer, no significant difference was observed between the head, the body and tail. The sensitivity, specificity, accuracy of pancreatic duct brushing in detecting pancreatic cancer was 70%, 94%, and 83%, respectively. CONCLUSION: K-ras analysis of pancreatic brushing samples is helpful in the diagnosis of patients with early pancreatic cancer.
文摘AIM: To determine bhe accuracy of p53 gene mutations predicted by overexpression of p53 protein immunohistochemically,and to investigate the co-mutation of p53 and K-ras genes in rectal cancer and its effect on promoting malignant biologic behaviors of tumors.METHODS: Ninety-seven specimens of rectal cancer were surgically resected in our hospital from August 1996 to October 1997. The hot mutation areas of p53 gene (in exons 5-8) and K-rasgene (in codon 5/12 and 13) were detected with polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), and overexpression of p53 protein was detected with immunohistochemistry (IHC) in the 97 specimens of rectal cancer. Correlation between gene mutations and tumor clinicopathologic factors was studied, and survival analysis was penfomed as well.RESULTS: There were 36 cases of p53 gene mutations in 61 p53 protein positive cases, and 21 cases of p53 gene non-mutation in 36 p53 protein negative cases respectively.The coincidence rate of p53 gene mutation by IHC method with PCR-SSCP method was 58.8% (57/97). The mutation rate of p53 gene was 52.6% (51/97), while K-ras gene mutation was observed in codons 12 and 13 in 61 cases with a mutation rate of 62.9% (61/97). Single gene mutation of p53 or K-raswas found in 32 cases. Both p53 and K-ras gene mutation were found in 48 cases. Statistical analysis showed that p53 and K-ras gene mutations were not related to the dinicopathologic factors, including tumor size, gross tumor type, histological dassification, differentiation, invasion to intestinal veins, lymphatics and nerves, invasive depth to.wall, lymph node metastasis, and Dukes' stages (P>0.05).The survival in patients with no gene mutation, single gene mutation and both gene mutations were similar (P>0.05).CONCLUSION: IHC has a certain false positive and false negative rate in detecting p53 gene mutations. Malignant biological behaviours of rectal cancer are not enhanced by p53 and K-rasgene mutations. Co-mutation of p53 and K-ras gene has neither synergic carcinogenesis-promoting effect,nor prognostic effect on rectal cancer.
基金Supported by Capital Public Health Project Cultivation Program,No.Z111107067311051
文摘AIM: To clarify the molecular mechanism involved in pathogenesis of colorectal cancer as well as clinical significance of genetic analysis of histological samples.
基金Supported by the Technology Committee of Shanghai,NO.994119044
文摘AIM:To investigate frequency and clinical significance of K-ras mutations in pancreatic diseases and to identify its diagnostic values in pancreatic carcinoma.METHODS:117 ductal lesions were identified in the available sections from pancreatic resection specimens of pancreatic ductal adenocarcinoma, comprising 24 pancreatic ductal adenocarcinoma, 19 peritumoral ductal atypical hyperplasia, 58 peritumoral ductal hyperplasia and 19 normal duct at the tumor free resection margin. 24 ductal lesions were got from 24 chronic pancreatitis. DNA was extracted.Codon 12 K-ras mutations were examined using the two-step polymerase chain reaction (PCR) combined with restriction enzyme digestion,followed by nonradioisotopic single-strand conformation polymorphism (SSCP) analysis and by means of automated DNA sequencing.RESULTS: K-ras mutation rate of the pancreatic carcinoma was 79%(19/24) which was significantly higher than that in the chronic pancreatitis 33%(8/24) (P<0.01). It was also found that K-ras mutation rate was progressively increased from normal duct at the tumor flee resectbn margin, peritumoral ductal hyperplasia, peritumoral ductal atypical hyperplasia to pancreatic ductal adenocardnoma. The mutation pattern of K-ras 12 codon of chronic pancreatitis was GGT→GAT, GGT and CGT,which is identical to that in pancreatic carcinoma.CONCLUSION:K-ras mutation may play a role in the malignant transformation of pancreatic ductal cell. K-ras mutation was not specific enough to diagnose pancreatic carcinoma.
基金National Natural Science foundation of China, No.39470332
文摘Objective:To study the role of the mutations of p53, APC and K-ras genes in 47 cases of 3 types of intestinal metaplasia (IM) of gastric mucosa. Methods:In 47 cases of IM, exons 5- 8 of p53 and exons 15 of APC were examined with PCR-SSCP and codon 12 of K-ras with PCR-RFLP to detect the existence of any mutations of these structures. Results:Muta- tions of p53, APC and K-ras were found in 29.8% (14/47),6.4% (3/47) and 6.4% (3/47) respectively in our series of patients who consisted of 33 with types I and II and 14 with type III of IM. The mutation rate of p53 was far higher in patients with type III IM (57.1%,8/14) than in those with types I and II IM(18.2%,6/33)(P <0.05). Though the mutation rate of APC and K-ras was also higher in the patients with type III IM than in those with types I and II IM, it was of no statistical significance (P >0.05). In one case of type III IM, mutation of both p53 and K-ras was found. Conclusion: The molecular changes of 3 types of IM are different. The mutation of p53 may be closely related to carcinogenesis in cases of type III IM and it serve as a sign for the early diagnosis of gastric carcinoma.
文摘Objective： To detect the style of K-ras gene point mutation in human pancreatic cancer cell line PANC-1 and decide the bp sequence of Ras target position interfered by RNA. Methods： Three kinds of special sequence primers （SSP） for polymerase chain reaction （PCR） with regard to the mutation styles （OAT, COT and GOT） at codon 12 of K-ras were used to study the human pancreatic cancer cell line PANC-1. The amplification products were studied with polyacrylamine gel electrophoresis to detect the style of point mutation. Results： The style of K-ras gene point mutation at codon 12 was OAT in human pancreatic cancer cell line. Conclusion： PCR-SSP is rapid, convenient and high specific. The results provide a basis for further gene therapy by RNA interference for pancreatic cancer.
文摘To evaluate the feasibility and clinical significance of the PCR SSP technique in detecting K ras gene mutation at codon 12 in pancreatic adenocarcinoma tissues. 80 specimens of surgical resection or biopsy samples were tested at our hospital from January 1994 to September 1995. Three different special sequence primers (SSP) synthesized according to mutation styles of CGT, GTT, GAT were respectively prepared. Three amplification reactions were performed for each sample. The amplification products were analyzed by conventional polyacrylamide gel electrophoresis, stained with ethidium bromide and observed under UV transillumination. Results: All of the 34 pancreatic adenocarcinoma samples had positive PCR results with the mutation rate 100%. 7 cases were CGT mutation, 18 GGT and 17 GAT mutation, in which 2 types of mutation existed in 8 cases. No mutation appeared in 13 normal pancreatic tissues, 6 insulinomas, 6 chronic pancreatitis, 5 benign pancreatic cysts, 7 bile duct carcinoma, 5 ampulla carcinoma and 4 carcinomas of duodenal papilla. Conclusion: Pancreatic adenocarcinoma is one of the commonly encounted tumors and is still very difficult to diagnose at the early stage and to distinguish from other lesions preoperatively. Our study indicates that PCR SSP is an ideal assay in comparison with other methods to detect K ras gene mutation. It is simple, rapid, specific, sensitive and easily generalized for clinical application on preoperative diagnosis.
文摘Objective: Molecular targeted drugs have been widely used in clinical application which has successfully prolonged some patients' life. Meanwhile, molecular targeted drug therapy for esophageal cancer are attracting more and more attention from doctors and experts. However, little study has been done towards the effect of this approach for treating esophageal squamous cell carcinoma. This paper, therefore, intends to explore the possibilities of applying EGFR-TKI inhibitors or anti-EGFR monoclonal antibody in esophageal squamous cell carcinoma by studying the mutations of EGFR, K-ras and B-raf in the esophageal squamous cell carcinoma tissues. Methods: Thirty-five cases of resected specimens of diagnosed esophageal squamous cell carcinoma with complete clinical and pathological data from January to April 2009 were collected. Pyrophosphate was used for observing the mutations of EGFR, K-ras and B-raf in the esophageal squamous cell carcinoma tissues. Results: Examinations were undertaken respectively to the codon segment 746-754 of exon 19 in EGFR genes, codon 12 and 13 in K-ras genes as well as condon 600 in B-raf genes. No mutation was found in EGFR and B-raf genes with mutation rate 0% (0/35), all of codon 12 in K-ras genes were wild-type without any mutation, while 2 specimens of codon 13 had mutations with mutation rate of 5.71% (2/35). Conclusion: In treating esophageal squamous cell carcinoma patients, all K-ras genes are expressed as wild type due to low mutation rate; cetuximab is effective due to low mutation rate of B-raf while EGFR-TKI inhibitor will not be effective enough because of low mutation rate of EGFR genes.
文摘OBJECTIVE To investigate gene mutations of epidermal growth factor receptor （EGFR） and K-RAS （Kirsten rat sarcoma viral oncogene） in Chinese patients with non-small cell lung cancer （NSCLC）, and study the correlation with its protein expression and its clinical significance on gefitinib.METHODS Detect the EGFR and K-RAS gene mutations status by gene sequencing and use the method of immunohistochemistry to detect EGFR and K-RAS protein expression.RESULTS The frequency of EGFR mutations was 33%, mainly located in exon 19 and exon 21. The frequency of K-RAS mutations was 5.5%, mainly located in codon 12. There was no case which both had EGFR and K-RAS mutations, suggesting a mutually exclusive relationship between the two. EGFR mutations are more common in adenocarcinomas （particularly those with bronchioloalveolar features）, nonsmokers and females. 16% were detected EGFR positive expression and had no correlation with EGFR mutation （P 〉 0.05）, but had significant correlation with mutation in exon 19 （P 〈 0.05）. The frequency of K-RAS positive expression was 52.5% and had no correlation with K-RAS mutation （P 〉 0.05）. Twelve （8 cases were protein-negative） out of 15 gefitinib-treated NSCLC patients with disease control carry EGFR mutations.CONCLUSION EGFR protein expression has some correlation with exon 19 mutations. Combined detection of EGFR and K-RAS gene mutations can help clinicians to choose patients who may benefit from EGFR tyrosine kinase inhibitor （EGFR-TKI） and to predict the response and prognosis of gefitinib.
