ABSTRACT
@# Objective: To investigate whether miR-140 could increase the sensitivity of cervical cancer (CC) to oxaliplatin by downregulating the expression of programmed death-1 (PD-L1). Methods: qPCR was used to analyze miR-140 expression in normal human cervical cells, CC cells and oxaliplatin-resistant CC cells. Cells were transfected with miR-140 mimic, and then, the proliferation of CC cells and oxaliplatin-resistant CC cells was detected by using CCK-8 assay, and the colony formation rate of CC cells was obtained by using colony formation assay. Starbase and TargetScan were used to predict the targeted binding site of miR-140 and PD-L1, and the influence of miR-140 on the expression of PD-L1 was validated by dual luciferase reporter gene assay.Annexin V FITC/PI double staining and Wb assays were used to detect the effect of over-expression of miR-140 or both over-expression of PD-L1 and miR140 on the apoptosis, migration and expression of apoptosis-related proteins in CC cells after treatment with oxaliplatin. Moreover, transplantation tumor of CC cell lines was established in nude mice to assess the effects of miR-140 on enhancing the sensitivity of tumors to oxaliplatin. Results: The expression of miR-140 was significantly decreased in oxaliplatin-resistant CC cells (P<0.01). Over-expression of miR140 could significantly increase the sensitivity of oxaliplatin-resistant CC cells to oxaliplatin (P<0.05), and inhibit the CC cells proliferation and colony formation (P<0.01). miR-140 showed targeted binding to PD-L1 3'-UTR and inhibited its expression. Over-expression of miR-140 significantly promoted CC cell migration and apoptosis (P<0.01). However, co-transfection of PD-L1 counteracts the effects of miR-140 on cell metastasis and apoptosis (all P<0.05). In addition, xenograft tumor model in mice also verified that miR-140 could promote the sensitivity of tumors to oxaliplatin. Conclusion: miR-140 increases the sensitivity of CC to oxaliplatin through inhibition of PD-L1 expression. Therefore, up-regulation of miR-140 or down-regulation of PD-L1 in combination with oxaliplatin may be a novel strategy for the treatment of Oxaliplatin-resistant CC.