MiR-590-5p Sensitizes Pancreatic Ductal Adenocarcinoma Cells to Radiation by Blocking Autophagy via Targeting ATG3

Abstract

Background: Resistance against radio therapy is growing concern in treating patients of pancreatic cancer (PC). Improving our depth with regards to mechanisms involved in radio resistance could help in developing strategies for increasing patient's response to this therapy. Here we investigated the role of micro RNAs (miRs) and specifically miR-590-5p in radio-resistance of PC cells. Methods: We successfully developed radio resistant PC cell lines in our lab and subjected them to microarray analysis to compare the levels of miRs with their original parental cell lines. We then transfected the PC cells using miR mimics or inhibitor and performed clonogenic survival assay to study the effects on radiation sensitivity. We also studied the effect of miR-590-5p on autophagy using electron microscopy and Immunoblotting analysis. Luciferase assay was done for identifying mRNA targets of miR-590-5p. Results: The radio resistant PC cells exhibited decreased expression of miR-590-5p with elevated autophagy against the parental cells. The over expression of miR-590-5p inhibited the radiation mediated autophagy and the miR-590-5p inhibitor encouraged autophagy in PC cells. The up-regulation of miR-590-5p enhanced the sensitivity of PC cells towards radiation. We confirmed that ATG-3 as a favorable target of miR-590-5p and was unregulated in radio resistant cells, we also found that ATG-3 was associated with autophagy. MiR-590-5p inhibited radiation-mediated autophagy and enhanced radio sensitivity of PC cells. The results suggested an inverse correlation for miR-590-5p and autophagy in PC tissues. Conclusions: The expression of miR-590-5p in PC cells is associated with elevated levels of autophagy along with ATG-3, which leads to radio resistance; miR-590-5p can be employed to enhance the radio sensitivity of PC cells. Funding Statement: The project was self financed. Declaration of Interests: The authors have no conflict of interest. Ethics Approval Statement: All the patients were educated about the study and informed consent forms were signed before the study. The study was approved from institutional review of research committee at The Second Xiangya Hosipital of Central South University, Changsha, Hunan, China