The Relationship between Autophagy Process and Expression of MicroRNA-146a-5p in MKN-45 and MCF-7 Cell Lines.

After chemotherapy or radiation therapy, autophagy activity increases in tumor cells for the adaptation of the tumor cells to stress. Thus, disturbance in autophagy can enhance the effectiveness of anticancer drugs. On the other hand, recent findings highlight the importance of microRNAs (miRs) in autophagy, including miR-146a-5p. In gastric and breast cancer miR-146a-5p is frequently reduced, and more precise identification of its function in these cancers is needed. The aim of this study was to evaluate the relationship between miR-146a-5p and autophagy in MKN-45 (human stomach cancer cell line) and MCF-7(breast cancer cell line). The expression of miR-146a-5p in MKN-45 and MCF-7 cell lines was measured before and after induction of autophagy using real-time polymerase chain reaction (PCR). A flow cytometry assay was used for the apoptosis assay, and autophagy induction was approved. Also, the formation of autophagic vacuoles was ensured in cells by western blotting and fluorescence microscopy. Real-time PCR showed that miR-146a-5p level in starvation groups, during autophagy, was significantly lower than in control groups, and also tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6) level, a key target of miR-146a-5p, in starvation groups, during autophagy, was more than control groups but it was significant only in the MCF-7 group. According to previous studies and the results of the present study, miR-146a-5p may be considered a negative regulator of autophagy. However, to confirm this, further studies are needed on different cancer cell lines.