The aim of this study is to investigate epigenetic mechanism of ABCG2 induced drug-resistance. It is not only expatiate for drug-resistance regulation mechanism in all-round, but also to provide scientific experimenta...The aim of this study is to investigate epigenetic mechanism of ABCG2 induced drug-resistance. It is not only expatiate for drug-resistance regulation mechanism in all-round, but also to provide scientific experimental basis for selecting target to reverse its drug-resistance. Apply methylation-specific PCR （MSP） to have tested methylation of ABCG2 promoter region -359 to -353 specific positions in breast cancer tissues and paired adjacent tissue of 22 cases and test their methylation positions with MSP products for sequencing; and adopt fluorescent quantitation RT-PCR to test expression level DNMT1, DNMT3A, DNMT3B and ABCG2; to make analysis on relationship between them with statistical spearman correlation. Specific positions of ABCG2 gene promoter region of 18 cases among the 22 cases with breast cancer （18/22, 82%） existed high methylation （P〈0.05）, MSP products sequencing proved methylation of the specific position, and mRNA expression level was relative higher in remarkable positive correlation （P〈0.05） ABCG2, DNMT1, DNMT3A, DNMT3B mRNA expression levels in breast cancer tissues were obviously higher than adjacent tissues （P〈0.01）, and DNMT3B expression level was obviously higher than DNMT1 and DNMT3A （P〈0.01） in negative correlation with ABCG2 gene expression （P=0.001）. -359 to -353 positions of promoter regions of ABCG2gene existed high methylation capable to push expression of this gene in beast cancer tissue. DNMT3B is involved in expression regulation in ABCG2 gene, and provides new scientific basis for drug-resistance target as reverse ABCG2 induction展开更多
Breast cancer resistance protein(BCRP)/ATP-binding cassette subfamily G member 2(ABCG2) is an ATP-binding cassette(ABC) transporter identified as a molecular cause of multidrug resistance(MDR) in diverse cancer cells....Breast cancer resistance protein(BCRP)/ATP-binding cassette subfamily G member 2(ABCG2) is an ATP-binding cassette(ABC) transporter identified as a molecular cause of multidrug resistance(MDR) in diverse cancer cells.BCRP physiologically functions as a part of a self-defense mechanism for the organism;it enhances elimination of toxic xenobiotic substances and harmful agents in the gut and biliary tract,as well as through the blood-brain,placental,and possibly blood-testis barriers.BCRP recognizes and transports numerous anticancer drugs including conventional chemotherapeutic and targeted small therapeutic molecules relatively new in clinical use.Thus,BCRP expression in cancer cells directly causes MDR by active efflux of anticancer drugs.Because BCRP is also known to be a stem cell marker,its expression in cancer cells could be a manifestation of metabolic and signaling pathways that confer multiple mechanisms of drug resistance,self-renewal(stemness),and invasiveness(aggressiveness),and thereby impart a poor prognosis.Therefore,blocking BCRP-mediated active efflux may provide a therapeutic benefit for cancers.Delineating the precise molecular mechanisms for BCRP gene expression may lead to identification of a novel molecular target to modulate BCRP-mediated MDR.Current evidence suggests that BCRP gene transcription is regulated by a number of trans-acting elements including hypoxia inducible factor 1α,estrogen receptor,and peroxisome proliferator-activated receptor.Furthermore,alternative promoter usage,demethylation of the BCRP promoter,and histone modification are likely associated with drug-induced BCRP overexpression in cancer cells.Finally,PI3K/AKT signaling may play a critical role in modulating BCRP function under a variety of conditions.These biological events seem involved in a complicated manner.Untangling the events would be an essential first step to developing a method to modulate BCRP function to aid patients with cancer.This review will present a synopsis of the impact of BCRP-mediated MDR in cancer cells,and the molecular mechanisms of acquired MDR currently postulated in a variety of human cancers.展开更多
基金Supported by the National Natural Science Foundation of China (30500599 and 30571592)the Natural Science Foundation of Guangdong (9151503102000019)the Medical Scientific Research Foundation of Guangdong (A2009606)
文摘The aim of this study is to investigate epigenetic mechanism of ABCG2 induced drug-resistance. It is not only expatiate for drug-resistance regulation mechanism in all-round, but also to provide scientific experimental basis for selecting target to reverse its drug-resistance. Apply methylation-specific PCR （MSP） to have tested methylation of ABCG2 promoter region -359 to -353 specific positions in breast cancer tissues and paired adjacent tissue of 22 cases and test their methylation positions with MSP products for sequencing; and adopt fluorescent quantitation RT-PCR to test expression level DNMT1, DNMT3A, DNMT3B and ABCG2; to make analysis on relationship between them with statistical spearman correlation. Specific positions of ABCG2 gene promoter region of 18 cases among the 22 cases with breast cancer （18/22, 82%） existed high methylation （P〈0.05）, MSP products sequencing proved methylation of the specific position, and mRNA expression level was relative higher in remarkable positive correlation （P〈0.05） ABCG2, DNMT1, DNMT3A, DNMT3B mRNA expression levels in breast cancer tissues were obviously higher than adjacent tissues （P〈0.01）, and DNMT3B expression level was obviously higher than DNMT1 and DNMT3A （P〈0.01） in negative correlation with ABCG2 gene expression （P=0.001）. -359 to -353 positions of promoter regions of ABCG2gene existed high methylation capable to push expression of this gene in beast cancer tissue. DNMT3B is involved in expression regulation in ABCG2 gene, and provides new scientific basis for drug-resistance target as reverse ABCG2 induction
文摘Breast cancer resistance protein(BCRP)/ATP-binding cassette subfamily G member 2(ABCG2) is an ATP-binding cassette(ABC) transporter identified as a molecular cause of multidrug resistance(MDR) in diverse cancer cells.BCRP physiologically functions as a part of a self-defense mechanism for the organism;it enhances elimination of toxic xenobiotic substances and harmful agents in the gut and biliary tract,as well as through the blood-brain,placental,and possibly blood-testis barriers.BCRP recognizes and transports numerous anticancer drugs including conventional chemotherapeutic and targeted small therapeutic molecules relatively new in clinical use.Thus,BCRP expression in cancer cells directly causes MDR by active efflux of anticancer drugs.Because BCRP is also known to be a stem cell marker,its expression in cancer cells could be a manifestation of metabolic and signaling pathways that confer multiple mechanisms of drug resistance,self-renewal(stemness),and invasiveness(aggressiveness),and thereby impart a poor prognosis.Therefore,blocking BCRP-mediated active efflux may provide a therapeutic benefit for cancers.Delineating the precise molecular mechanisms for BCRP gene expression may lead to identification of a novel molecular target to modulate BCRP-mediated MDR.Current evidence suggests that BCRP gene transcription is regulated by a number of trans-acting elements including hypoxia inducible factor 1α,estrogen receptor,and peroxisome proliferator-activated receptor.Furthermore,alternative promoter usage,demethylation of the BCRP promoter,and histone modification are likely associated with drug-induced BCRP overexpression in cancer cells.Finally,PI3K/AKT signaling may play a critical role in modulating BCRP function under a variety of conditions.These biological events seem involved in a complicated manner.Untangling the events would be an essential first step to developing a method to modulate BCRP function to aid patients with cancer.This review will present a synopsis of the impact of BCRP-mediated MDR in cancer cells,and the molecular mechanisms of acquired MDR currently postulated in a variety of human cancers.
