Effect of TET1 regulating MGMT on chemotherapy resistance of oral squamous cell carcinoma stem cells

The study was to evaluate the effect of ten-eleven translocation 1 (TET1) regulating o6-methylguanine-DNA methyltransferase (MGMT) in chemotherapy resistance of oral squamous cell carcinoma (OSCC) stem cells. OSCC stem cells were divided into the blank, negative control (NC), TET1-siRNA, TET1-siRNA+MGMT-OE, and MGMT-OE groups. Methylation-specific polymerase chain reaction (MSP), qRT-PCR and Western blotting were conducted to detect the methylation status of MGMT, expressions of TET1, MGMT, ABCG2, and Oct-4. Cell proliferation, cisplatin chemosensitivity, and cell cycle and apoptosis, were detected using CCK8 and flow cytometry. A chromatin immunoprecipitation (ChIP) assay was employed for detecting the link between TET1 and MGMT gene promoters. In comparison to the NC group, the TET1-siRNA group exhibited increased levels of MGMT methylation, the number of apoptotic cells and cisplatin chemosensitivity consisting of varying concentrations, however, decreased levels of mRNA and protein expressions of TET1 as well as MGMT, cell viability, the number of cells in the S phase, and protein expressions of ABCG2 and Oct-4 were all have diminished amounts. The TET1-siRNA+MGMT-OE and MGMT-OE groups had higher MGMT mRNA and protein expression, as well as increased protein expressions of ABCG2 and Oct-4, greater cell activity, higher number of cells in the S phase, decreased apoptotic rates in cells and decreased cisplatin chemosensitivity with different concentrations. Our study provided evidence that low-expression of TET1 in OSCC stem cells may stimulate MGMT promoter methylation, while inhibiting MGMT mRNA expression, this ultimately strengthens the sensitivity of OSCC stem cells in regards to chemotherapeutics.