Insulin-like Growth Factor-? Induces Chemoresistence To Docetaxel By Regulating MiR-143 In Human Prostate Cancer

BackgroundProstate cancer(PC)is the second leading cause of cancer death among men in the United States and the fourth most common tumor type worldwide Docetaxel is widely used as a first-line drug for chemotherapy,but resistance to docetaxel is a hindrance for PC treatment.It has been demonstrated that miR-143 is a tumor suppressor in several types of cancer.Insulin-like growth factor(IGF)axis is one of the most investigated targets in PC,and targeting IGF axis showed promising anti-tumor capabilities in preclinical studies.A novel mechanism of miR-143 in docetaxel resistance in PC,which is useful for developing new mechanism-based prognostic biomarker and treatment option for PC in the future.ObjectiveTo investigate the role of insulin like growth factor-1(IGF-I)in prostate cancer cells,and to explore the molecular mechanism of miR-143 to IGF-I-induced chemoresistance to docetaxel treatment in prostate cancer cells.Methods1.Lentivirus carrying miR-143 and miR-NC were packaged in HEK-293T cells.Stable cell lines PC-3/miR-143 and PC-3/miR-NC were established by lentiviral transduction.The capability of cell proliferation was measured using a CCK8 kit at different indicated time points.2.Real time Polymerase Chain Reaction assay were performed to detect the expression of miR-143,IGF-IR,IRS1 and VEGF in prostate cancer cells.Western blotting assay were performed to analyzed the protein expression of IGF-IR,IRS1 and VEGF.3.For plasmid transient transfection,PC-3 cells stably expressing miR-143 or negative control were co-transfected witih VEGF reporter,pRL-TK vector plasmid using Lipofectamine 2000.Firefly luciferase(Luc)and Renilla luciferase activities were measured using a dual luciferase assay kit.4.Aliquots of cells were subcutaneously injected into each side of the posterior flank of nude mice.Tumor size was measured using vernier caliper every 2 days.14 days after implantation,IGF-I and docetaxel were intraperitoneal injected into mice.Results1.IGF-I promoted chemoresistance to docetaxel in PC cells.IGF-I treatment induced IGF-IR and IRS1 expression in PC cells.2.MiR-143 suppressed IGF-I induced chemoresistance to docetaxel,the expression of IGF-IR and IRS1,and VEGF transcriptional activation in PC cells.IGF-IR and IRS1 were downstream targets of miR-143 to inhibit VEGF transcriptional activation 3.MiR-143 inhibited tumor growth,miR-143 sensitized PC cells to docetaxel and IGF-I treatment in vivoConclusionIn the present study,we found that IGF-I efficiently rendered PC-3 and DU 145 cells more resistant to docetaxel treatment.Docetaxel decreased miR-143 and increased its targets IGF-IR and IRS1 expresssion.Moreover,miR-143 inhibited VEGF transcriptional activation through IGF-IR and IRS1,and suppressed IGF-I-induced chemoresistance to docetaxel treatment.Finally,miR-143 inhibited tumor growth and increased sensitivity of PC to docetaxel and IGF-I treatament in vivo.In summary,we report here that IGF-I induces chemoresistence to docetaxel in PC,and miR-143 and its targets IGF-IR and IRS1 are involved in this process.