A significant number of anticancer drugs fail to treat primary and metastatic brain tumors primarily because of the complex blood-brain barrier(BBB)and overexpression of ATP-binding cassette(ABC)transporters,which dec...A significant number of anticancer drugs fail to treat primary and metastatic brain tumors primarily because of the complex blood-brain barrier(BBB)and overexpression of ATP-binding cassette(ABC)transporters,which decrease drug penetration into the central nervous system and ultimately into tumors.It is noteworthy that the ABC transporters,ABCB1[known as P-glycoprotein(P-gp)]and ABCG2[known as breast cancer resistance protein(BCRP)],are overexpressed in brain tumors,including common gliomas.The co-presence of these transporters may negate the inhibition of either transporter,particularly if both transport the same anticancer drug.The cellular export of drugs by ABC transporters has been implicated in mediating resistance to anticancer drugs.However,the clinical relevance as a therapeutic target in human tumors remains a matter of contention.Although effective and clinically approved ABC transporter inhibitors could potentially overcome drug resistance,none are currently approved.Furthermore,the ABC transporter inhibitors in clinical trials produced low or no clinical efficacy,significant toxicities,and unsuitable pharmacokinetic profiles.Therefore,innovative approaches are needed to efficaciously and simultaneously inhibit these transporters to surmount anticancer drug resistance.This review emphasizes the clinical significance of ABC transporters in diminishing the efficacy of brain tumor treatments.The molecular alterations in BBB following brain tumor development,which are linked to various cancer therapies,are discussed.The overexpression of ABCB1 and ABCG2 at the BBB is discussed,potential strategies to decrease the export of chemotherapeutics by these transporters and the associated challenges and failures are discussed,and the implementation of novel approaches is considered.展开更多
Imatinib,a breakpoint cluster region(BCR)-Abelson murine leukemia(ABL) tyrosine kinase inhibitor(TKI),has revolutionized the treatment of chronic myelogenous leukemia(CML).However,development of multidrug resistance(M...Imatinib,a breakpoint cluster region(BCR)-Abelson murine leukemia(ABL) tyrosine kinase inhibitor(TKI),has revolutionized the treatment of chronic myelogenous leukemia(CML).However,development of multidrug resistance(MDR) limits the use of imatinib.In the present study,we aimed to investigate the mechanisms of cellular resistance to imatinib in CML.Therefore,we established an imatinib-resistant human CML cell line(K562-imatinib) through a stepwise selection process.While characterizing the phenotype of these cells,we found that K562-imatinib cells were 124.6-fold more resistant to imatinib than parental K562 cells.In addition,these cells were cross-resistant to second-and third-generation BCR-ABL TKIs.Western blot analysis and reverse transcription-polymerase chain reaction(RT-PCR) demonstrated that P-glycoprotein(P-gp) and MDR1 mRNA levels were increased in K562-imatinib cells.In addition,accumulation of [14C]6-mercaptopurine(6-MP) was decreased,whereas the ATP-dependent efflux of [14C]6-MP and [3H]methotrexate transport were increased in K562-imatinib cells.These data suggest that the overexpression of P-gp may play a crucial role in acquired resistance to imatinib in CML K562-imatinib cells.展开更多
Evidence-based research has confirmed the role of gastrointestinal microbiota in regulating intestinal inflammation.These data have generated interest in developing microbiota-based therapies for the prevention and ma...Evidence-based research has confirmed the role of gastrointestinal microbiota in regulating intestinal inflammation.These data have generated interest in developing microbiota-based therapies for the prevention and management of inflammatory bowel disease(IBD).Despite in-depth understanding of the etiology of IBD,it currently lacks a cure and requires ongoing management.Accumulating data suggest that an aberrant gastrointestinal microbiome,often referred to as dysbiosis,is a significant environmental instigator of IBD.Novel microbiome-targeted interventions including prebiotics,probiotics,fecal microbiota transplant,and small molecule microbiome modulators are being evaluated as therapeutic interventions to attenuate intestinal inflammation by restoring a healthy microbiota composition and function.In this review,the effectiveness and challenges of microbiome-centered interventions that have the potential to alleviate intestinal inflammation and improve clinical outcomes of IBD are explored.展开更多
The protein,N-myc downstream-regulated gene 2(NDRG2),a tumor suppressor,is significantly decreased or absent in many types of cancer.There is a significant negative correlation between the levels of NDRG2 and the deve...The protein,N-myc downstream-regulated gene 2(NDRG2),a tumor suppressor,is significantly decreased or absent in many types of cancer.There is a significant negative correlation between the levels of NDRG2 and the development and progression of cancer tumor recurrence and tumor invasion,in different cancers.In contrast,the in vitro and in vivo overexpression of the NDRG2 protein decreases the proliferation,growth,adhesion and migration of many types of cancer cells.The in vitro overexpression of NDRG2 increases the efficacy of certain anticancer drugs in specific types of cancer cells.We hypothesize that the delivery of the mRNA of the NDRG2 protein,encapsulated by lipid nanoparticles,could represent a potential treatment of metastatic and drug-resistant cancers.This would be accomplished using a self-amplifying mRNA that encodes the NDRG2 protein and an RNA-dependent-RNA polymerase,obtained from an in vitrotranscribed(IVT)mRNA.The IVT mRNA would be encapsulated in a lipid nanoformulation.The efficacy of the nanoformulation would be determined in cultured cancer cells and if the results are positive,nude mice transplanted with either drug-resistant or metastatic drug-resistant cancer cells,would be treated with the nanoformulation and monitored for efficacy and adverse effects.If the appropriate preclinical studies indicate this formulation is efficacious and safe,it is possible it could be evaluated in clinical trials.展开更多
基金supported by Arkansas Bioscience Institute funds (ABI-GR020025) from University of Arkansas for Medical Sciences
文摘A significant number of anticancer drugs fail to treat primary and metastatic brain tumors primarily because of the complex blood-brain barrier(BBB)and overexpression of ATP-binding cassette(ABC)transporters,which decrease drug penetration into the central nervous system and ultimately into tumors.It is noteworthy that the ABC transporters,ABCB1[known as P-glycoprotein(P-gp)]and ABCG2[known as breast cancer resistance protein(BCRP)],are overexpressed in brain tumors,including common gliomas.The co-presence of these transporters may negate the inhibition of either transporter,particularly if both transport the same anticancer drug.The cellular export of drugs by ABC transporters has been implicated in mediating resistance to anticancer drugs.However,the clinical relevance as a therapeutic target in human tumors remains a matter of contention.Although effective and clinically approved ABC transporter inhibitors could potentially overcome drug resistance,none are currently approved.Furthermore,the ABC transporter inhibitors in clinical trials produced low or no clinical efficacy,significant toxicities,and unsuitable pharmacokinetic profiles.Therefore,innovative approaches are needed to efficaciously and simultaneously inhibit these transporters to surmount anticancer drug resistance.This review emphasizes the clinical significance of ABC transporters in diminishing the efficacy of brain tumor treatments.The molecular alterations in BBB following brain tumor development,which are linked to various cancer therapies,are discussed.The overexpression of ABCB1 and ABCG2 at the BBB is discussed,potential strategies to decrease the export of chemotherapeutics by these transporters and the associated challenges and failures are discussed,and the implementation of novel approaches is considered.
基金supported by start-up funding from St.John's University(Z.S.Chen)
文摘Imatinib,a breakpoint cluster region(BCR)-Abelson murine leukemia(ABL) tyrosine kinase inhibitor(TKI),has revolutionized the treatment of chronic myelogenous leukemia(CML).However,development of multidrug resistance(MDR) limits the use of imatinib.In the present study,we aimed to investigate the mechanisms of cellular resistance to imatinib in CML.Therefore,we established an imatinib-resistant human CML cell line(K562-imatinib) through a stepwise selection process.While characterizing the phenotype of these cells,we found that K562-imatinib cells were 124.6-fold more resistant to imatinib than parental K562 cells.In addition,these cells were cross-resistant to second-and third-generation BCR-ABL TKIs.Western blot analysis and reverse transcription-polymerase chain reaction(RT-PCR) demonstrated that P-glycoprotein(P-gp) and MDR1 mRNA levels were increased in K562-imatinib cells.In addition,accumulation of [14C]6-mercaptopurine(6-MP) was decreased,whereas the ATP-dependent efflux of [14C]6-MP and [3H]methotrexate transport were increased in K562-imatinib cells.These data suggest that the overexpression of P-gp may play a crucial role in acquired resistance to imatinib in CML K562-imatinib cells.
基金supported by Career Development Award[ID#597229]from Crohn’s and Colitis Foundation,National Institutes of Health(NIH)award R01 DK133334,and NIH T32 award T32DK120509.
文摘Evidence-based research has confirmed the role of gastrointestinal microbiota in regulating intestinal inflammation.These data have generated interest in developing microbiota-based therapies for the prevention and management of inflammatory bowel disease(IBD).Despite in-depth understanding of the etiology of IBD,it currently lacks a cure and requires ongoing management.Accumulating data suggest that an aberrant gastrointestinal microbiome,often referred to as dysbiosis,is a significant environmental instigator of IBD.Novel microbiome-targeted interventions including prebiotics,probiotics,fecal microbiota transplant,and small molecule microbiome modulators are being evaluated as therapeutic interventions to attenuate intestinal inflammation by restoring a healthy microbiota composition and function.In this review,the effectiveness and challenges of microbiome-centered interventions that have the potential to alleviate intestinal inflammation and improve clinical outcomes of IBD are explored.
文摘The protein,N-myc downstream-regulated gene 2(NDRG2),a tumor suppressor,is significantly decreased or absent in many types of cancer.There is a significant negative correlation between the levels of NDRG2 and the development and progression of cancer tumor recurrence and tumor invasion,in different cancers.In contrast,the in vitro and in vivo overexpression of the NDRG2 protein decreases the proliferation,growth,adhesion and migration of many types of cancer cells.The in vitro overexpression of NDRG2 increases the efficacy of certain anticancer drugs in specific types of cancer cells.We hypothesize that the delivery of the mRNA of the NDRG2 protein,encapsulated by lipid nanoparticles,could represent a potential treatment of metastatic and drug-resistant cancers.This would be accomplished using a self-amplifying mRNA that encodes the NDRG2 protein and an RNA-dependent-RNA polymerase,obtained from an in vitrotranscribed(IVT)mRNA.The IVT mRNA would be encapsulated in a lipid nanoformulation.The efficacy of the nanoformulation would be determined in cultured cancer cells and if the results are positive,nude mice transplanted with either drug-resistant or metastatic drug-resistant cancer cells,would be treated with the nanoformulation and monitored for efficacy and adverse effects.If the appropriate preclinical studies indicate this formulation is efficacious and safe,it is possible it could be evaluated in clinical trials.
