MicroRNAs （miRNAs） are small, noncoding RNAs which can often act as an oncogene or a tumor suppressor. Several miRNAs are associated with the development of hepatoceUular carcinoma （HCC）. We demonstrated that miR-...MicroRNAs （miRNAs） are small, noncoding RNAs which can often act as an oncogene or a tumor suppressor. Several miRNAs are associated with the development of hepatoceUular carcinoma （HCC）. We demonstrated that miR-125b significantly suppresses HCC cell proliferation and promotes apoptosis by inhibiting the gene expression of the anti-apoptotic protein, Bcl-2. Bioinformatic analysis indicated that the 3tUTR of Bcl-2 has binding sites for miR-I25b, Luciferase reporter assay confirmed the ability of miR-125b to dramatically suppress Bcl-2 transcription, suggesting that Bcl-2 is a target gene for miR-125b. We concluded that miR-125b acts as a tumor suppressor in hepatic tumor development by targeting Bcl-2 and inducing cancer celt apoptosis.展开更多
Chemotherapy is the preferred therapeutic approach for advanced ovarian cancer,but a successful long-term treatment is prevented by the development of drug resistance.Recent works have underlined the involvement of no...Chemotherapy is the preferred therapeutic approach for advanced ovarian cancer,but a successful long-term treatment is prevented by the development of drug resistance.Recent works have underlined the involvement of non-coding RNAs,microRNAs（miRNAs） in cancer development,with several conjectures regarding their possible involvement in the evolution of drug resistance.This study is to investigate the promoting effects and mechanism of miR-125b involved in the development of chemoresistance in ovarian cancer.The different expression of miR-125b in cisplatin-sensitive ovarian cancer cell line（OV2008） and its resistant variant（C13＊） was identified by real-time PCR.An in vitro cytotoxicity assay and apoptosis assay using CCK-8 assay and flow cytometry,were carried out to detect the effect of miR-125b and Bak1 on cisplatin resistance of cells.Real-time PCR,Western blotting and luciferase reporter assay were used to detect whether Bak1 is a target of miR-125b.As compared with OV2008 cells,the expression levels of miR-125b in C13＊ cells were increased.It was found that the up-regulation of microRNA-125b caused a marked inhibition of cisplatin-induced cytotoxicity and apoptosis and a subsequent increase in the resistance to cisplatin in OV2008 and C13＊ cells.Moreover,Bak1 was a direct target of miR-125b,and down-regulation of Bak1 suppressed cisplatin-induced apoptosis and led to an increased resistance to cisplatin.Our study indicates that miR-125b has a significantly promoting effect on chemoresistance of C13＊ cells and up-regulation of miR-125b expression contributes to cisplatin resistance through suppression of Bak1 expression.This finding has important implications in the development of targeted therapeutics for overcoming cisplatin resistance in ovarian cancer.展开更多
基金supported by the National High Technology Research and Development Program of China(No. 2006AA02A107)the Major State Basic Research Program of China(Nos.2009CB521704 and 2010CB945504)the National Nature Science Foundation of China(No.30873031)
文摘MicroRNAs （miRNAs） are small, noncoding RNAs which can often act as an oncogene or a tumor suppressor. Several miRNAs are associated with the development of hepatoceUular carcinoma （HCC）. We demonstrated that miR-125b significantly suppresses HCC cell proliferation and promotes apoptosis by inhibiting the gene expression of the anti-apoptotic protein, Bcl-2. Bioinformatic analysis indicated that the 3tUTR of Bcl-2 has binding sites for miR-I25b, Luciferase reporter assay confirmed the ability of miR-125b to dramatically suppress Bcl-2 transcription, suggesting that Bcl-2 is a target gene for miR-125b. We concluded that miR-125b acts as a tumor suppressor in hepatic tumor development by targeting Bcl-2 and inducing cancer celt apoptosis.
基金supported by grants from the National Natural Sciences Foundation of China (No.81001153)the "973" Program of China (No. 2009CB521808)
文摘Chemotherapy is the preferred therapeutic approach for advanced ovarian cancer,but a successful long-term treatment is prevented by the development of drug resistance.Recent works have underlined the involvement of non-coding RNAs,microRNAs（miRNAs） in cancer development,with several conjectures regarding their possible involvement in the evolution of drug resistance.This study is to investigate the promoting effects and mechanism of miR-125b involved in the development of chemoresistance in ovarian cancer.The different expression of miR-125b in cisplatin-sensitive ovarian cancer cell line（OV2008） and its resistant variant（C13＊） was identified by real-time PCR.An in vitro cytotoxicity assay and apoptosis assay using CCK-8 assay and flow cytometry,were carried out to detect the effect of miR-125b and Bak1 on cisplatin resistance of cells.Real-time PCR,Western blotting and luciferase reporter assay were used to detect whether Bak1 is a target of miR-125b.As compared with OV2008 cells,the expression levels of miR-125b in C13＊ cells were increased.It was found that the up-regulation of microRNA-125b caused a marked inhibition of cisplatin-induced cytotoxicity and apoptosis and a subsequent increase in the resistance to cisplatin in OV2008 and C13＊ cells.Moreover,Bak1 was a direct target of miR-125b,and down-regulation of Bak1 suppressed cisplatin-induced apoptosis and led to an increased resistance to cisplatin.Our study indicates that miR-125b has a significantly promoting effect on chemoresistance of C13＊ cells and up-regulation of miR-125b expression contributes to cisplatin resistance through suppression of Bak1 expression.This finding has important implications in the development of targeted therapeutics for overcoming cisplatin resistance in ovarian cancer.
