摘要
AIM: To search for the biomarker of cellular immortalization, the telomere length, telomerase activity and its subunits in cultured epithelial cells of human fetal esophagus in the process of immortalization. METHODS: The transgenic cell line of human fetal esophageal epithelium (SHEE) was established with E(6)E(7) genes of human papillomavirus (HPV) type 18 in our laboratory. Morphological phenotype of cultured SHEE cells from the 6th to 30th passages, was examined by phase contrast microscopy, the telomere length was assayed by Southern blot method, and the activity of telomerase was analyzed by telomeric repeat amplification protocol (TRAP). Expressions of subunits of telomerase, hTR and hTERT, were assessed by RT-PCR. DNA content in cell cycle was detected by flow cytometry. The cell apoptosis was examined by electron microscopy (EM) and TUNEL label. RESULTS: SHEE cells from the 6th to 10th passages showed cellular proliferation with a good differentiation. From the 12th to the 16th passages, many senescent and apoptotic cells appeared, and the telomere length sharply shortened from 23kb to 17kb without expression of hTERT and telomerase activity. At the 20th passage, SHEE cells overcame the senescence and apoptosis and restored their proliferative activity with expression of telomerase and hTERT at low levels, but the telomere length shortened continuously to the lowest of 3kb. After the 30th passage cells proliferation was restored by increment of cells at S and G2M phase in the cell cycle and telomerase activity expressed at high levels and with maintenance of telomere length. CONCLUSION: At the early stage of SHEE cells, telomeres are shortened without expression of telomerase and hTERT causing cellular senescence and cell death. From the 20th to the 30th passages, the activation of telomerase and maintenance of telomere length show a progressive process for immortalization of esophageal epithelial cells. The expression of telomerase may constitute a biomarker for detection of immortalization of cells.
AIM: To search for the biomarker of cellular immortalization,the telomere length, telomerase activity and its subunits incultured epithelial cells of human fetal esophagus in theprocess of immortalization.METHODS: The transgenic cell line of human fetalesophageal epithelium (SHEE) was established with E6 E7genes of bt man papillomavirus (HPV) type 18 in ourlaboratory. Morphological phenotype of cultured SHEE cellsfrom the 6th to 30th passages, was examined by phasecontrast microscopy, the telomere length was assayed bySouthern blot method, and the activity of telomerase wasanalyzed by telomeric repeat amplification protocol (TRAP).Expressions of subunits of telomerase, hTR and hTERT,were assessed by RT-PCR. DNA content in cell cycle wasdetected by flow cytometry. The cell apoptosis wasexamined by electron microscopy (EM) and TUNEL label.RESULTS: SHEE cells from the 6 th to 10 th passagesshowed cellular proliferation with a good differentiation.From the 12 th to the 16 th passages, many senescent andapoptotic cells appeared, and the telomere length sharplyshortened from 23 kb to 17 kb without expression of hTERTand telornerase activity. At the 20 th passage, SHEE cellsovercame the senescence and apoptosis and restored theirproliferative activity with expression of telomerase andhTERT at low levels, but the telomere length shortenedcontinuously to the lowest of 3 kb. After the 30 th passagecells proliferation was restored by increment of cells at S andG2M phase in the cell cycle end telomerase activity expressedat high levels and with maintenance of telomere length.CONCLUSION: At the early stage of SHEE cells, telomeresare shortened without expression of telomerase and hTERTcausing cellular senescence and cell death. From the 20 thto the 30 th passages, the activation of telomerase andmaintenance of telomere length show a progressive processfor immortalization of esophageal epithelial cells. Theexpression of telomerase may constitute a biomarker fordetection of immortalization of cells.
作者
Zhong-Ying Shen Li-Yan Xu Wei-Jia Cai Min-Hua Chen Jian Shen,Department of Tumor Pathology,Medical College of Shantou University,Shantou 515031,Guangdong Province,China En-Min Li,Department of Biochemistry and Molecular Biology,Medical College of Shantou University,Shantou 515031,Guangdong Province,China Yi Zeng,Institute of Virology,Chinese Academy of Preventive Medicine,Beijing 100052,China
基金
the National Natural Science Foundation of Chines,No.39830380
