Abstract 5037: Upregulated superoxide dismutase 2 by specificity protein 1 mediates temozolomide resistance in glioma stem cells

Abstract

Abstract The resisitant mechanism of glioblastoma mutliforme (GBM) to the standard chemotherapy temozolomide (TMZ) can be attributed to methylguanine methyltransferase (MGMT) expression in only half of the clinical cases. For the other half, it is not fully understood. To elucidate the mechanism, MGMT-negative GBM cell lines, U87MG and A172, were used to develop the TMZ-resistant variants. The variants showed reduced reactive oxygen species (ROS) accumulation by TMZ treatment comparing to the parental one. Further analysis of the cells revealed enhanced expression of superoxide dismutases 2 (SOD2), an antioxidative enzyme, as well as the stem cell-like properties. The protein was shown to associate with glioma stem cells (GSC). Notably, inhibition of SOD2 by diethyldithiocarbamate attenuated the stemness properties and the viability of the resistant variants. Further investigation of the promotor binding study suggested specificity protein 1 (Sp1) as the key factor of the SOD2 response. Moreover, Sp1 expression was even enhanced in the spheroid cells and the TMZ-resistant U87MG cell line. Conversely, treatment with Sp1 inhibitor mithramycin A attenuates SOD2 expression and the stemness properties of the resistant variants. In summary, our results suggested a novel role of SOD2 in TMZ resistant mechanism of GBM. Further study of Sp1-SOD2 pathway as a therapeutic target to restore susceptibility of chemotherapy is therefore warranted. Citation Format: Jian-Ying Chuang, Jr-Jiun Liu, Shao-Wen Chou, Wen-Chang Chang, Kwang-Yu Chang. Upregulated superoxide dismutase 2 by specificity protein 1 mediates temozolomide resistance in glioma stem cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5037.