Il6-Stat3 Signaling Promotes Glioma Stem Cell (Gsc) Survival Under Hypoxia Environment Through Inhibition Of Cell-Death Inducing Gene Bnip3

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Glioblastomas (GBMs) are the most common and lethal brain tumor in adults. In rapid-growing tumors like malignant glioma, hypoxia is an unavoidable condition even with aggressive angiogenesis. Recent studies implicate an important role for a restricted population of neoplastic cells (glioma stem cells, GSCs) in glioma maintenance and recurrence. However, how these glioma stem cells survive and escape from harsh conditions like hypoxia is barely known. Our previous study and others’ have shown that GSCs preferentially express the interleukin 6 (IL6) receptors and Stat3 signaling is preferentially activated in GSCs. We further found that perturbation of IL6 signaling in GSCs reduced Stat3 activation, and small molecule inhibitors of Stat3 potently induced GSC cell death partially through induction of a BCL2 family member Bnip3. Despite its controversial role in cell survival, massive expression of Bnip3 is a well-studied mediator of cell death in hypoxic tumor cells. Furthermore, we found that enhanced IL6-Stat3 signaling in GSCs could counter the induction of Bnip3 under hypoxia, which provided an extra survival advantage for these glioma stem cells under severe hypoxic condition. These data indicated that Stat3 is a downstream mediator of pro-survival IL6 signals in GSCs partially through suppressing Bnip3 expression, especially under hypoxia condition. Together, our data indicate that IL6-Stat3 signaling contributes to glioma malignancy through the promotion of GSC survival under harsh conditions like hypoxia, and that targeting IL6-Stat3 signaling pathway may offer benefit for glioma patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3311. doi:10.1158/1538-7445.AM2011-3311