[Enhanced chemosensitivity of Hep-2 through down-regulating expression of SOX2 by RNAi]

To investigate the effect of SOX2 on chemotherapy sensitivity of human laryngeal epithelial cells Hep-2.

We designed and synthesized RNAis for silencing the expression of SOX2 in Hep-2 cells and selected the most effective RNAi by Western blot analysis. Then the recombinant plasmids of pGCsi-H1-SOX2 and pGCsi-H1-NC were constructed and transfected into Hep-2 cells to build cell lines of psiSOX2-Hep-2 and psiNC-Hep-2. CCK-8 assay had been used to test the sensitivity of Hep-2 cells to 5-FU and PTX after silencing SOX2 expression. Hoechst staining had been used to exam the changes of Hep-2 cells apoptosis treatment by 5-FU and PTX after silencing SOX2 expression. Furthermore, the changes of apoptosis-related genes expressions were detected by Western blotting.

The cell lines of psiSOX2-Hep-2 and psiNC-Hep-2 were successfully established, and the expression of SOX2 protein was decreased 78% in psiSOX2-Hep-2 cells compared with psiNC-Hep-2 cells. After reducing SOX2 expression, the sensitivity of Hep-2 cells to 5-FU and PTX were increased and the IC50 values for 48 h were decreased to 8.12 μg/ml and 5.16 μg/ml. Meanwhile, the apoptosis rate and the expression of apoptotic gene Bax and cleaved caspase-3 expression were dramatically increased and anti-apoptotic genes survivin and Bcl-2 were significantly decreased in psiSOX2-Hep-2 cells compared with psiNC-Hep-2 cells.

Down-regulating the protein expression of SOX2 by RNAi will significantly enhance the sensitivity of human laryngeal epithelial cells Hep-2 to 5-FU and PTX.