Side population were reduced by Nitidine chloride through suppressing STAT 3 / c-myc signaling via miR-17-5 p in gastric cancer

Objective: To explore the changes of side population (SP) after treated with Nitidine chloride (NC) in human gastric cancer cells MKN-45 and OCUM-2MD3, and mechanism of it, specially, to find which proteins and miRs were involved in this process. Methods: MKN-45 and OCUM-2MD3 cells were treated with varying concentrations of NC for 72 hours. The changes of SP were detected by flow cytometry. The related proteins were tested through Western blot analysis and the miRs were detected by stem-loop RT-PCR, respectively. Among them STAT3, c-myc and miR17-5p were observed to play an important role in SP cells after NC treatment. Results: The SP cells were obvious reduced after NC treatment in MKN-45 and OCUM-2MD3. NC suppressed the expression of STAT3 and c-myc and resulted in great increased miRs, especially miR-17-5p which was one of the mostly changed miRs and its level was increased about times. More interestingly, the decrease of SP was caused by the down regulation of c-mycvia inhibited STAT3. Furthermore, the experiment of above two cell lines with knock down STAT3 or c-myc and miR-17-5p or miR-17-5pinhibitor treatments proved the over expression of miR-17-5p reduced SP by inhibited STAT3/c-myc, and so we think it was an upstream gene of STAT3. Conclusions: Down regulation of STAT3 and c-myc and over expression of miR-17-5p reduced SP after NC treatment. Subsequently, NC reduced SP through suppressing STAT3/c-myc signaling via miR-17-5p in gastric cancer cells MNK-45 and OCUM-2MD3.