Bazedoxifene inhibits sustained STAT3 activation and increases survival in GBM

• Published in: Translational oncology Vol. 14; no. 11; p. 101192
• Main Authors: Wightman, Samantha M., Alban, Tyler J., Chen, Xing, Lathia, Justin D., Wang, Yuxin, Stark, George R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2021; Neoplasia Press; Elsevier
• Subjects: Bazedoxifene; Cancer stem cells; Glioblastoma; Glioma stem cells; IL6; Original Research; STAT3; Glioma stem cells; BBB; PDX; Bazedoxifene; Glioblastoma; STAT3; IP; BZA; CNS; eLDA; EGFR; SOCS3; IL6; GBM; GSC; IL6Rα; Cancer stem cells; JAK1
• ISSN: 1936-5233; 1936-5233
• DOI: 10.1016/j.tranon.2021.101192

•High STAT3 is correlated with poor prognosis in GBM.•Bazedoxifene targets IL-6-mediated sustained STAT3 activation.•STAT3 drives glioma stem cell maintenance, bazedoxifene targets this pathway.•Bazedoxifene crosses the BBB and prolongs survival in GBM bearing mice.•Bazedoxifene-treated tumors have less activated STAT3. An important factor correlated with poor survival in glioblastoma (GBM) is the aberrant and persistent activation of STAT3, a critical transcription factor that regulates multiple genes with key roles in cell survival, proliferation, resistance to chemotherapy, and stem cell maintenance. The Interleukin-6 (IL6)-STAT3 signaling axis has been studied extensively in inflammation and cancer. However, it is not completely understood how high levels of activated STAT3 are sustained in tumors. Previously, we identified a novel mechanism of biphasic activation of STAT3 in response to gp130-linked cytokines, including IL6, in which activation of STAT3 is prolonged by circumventing the negative regulatory mechanisms induced by its initial activationTo target prolonged STAT3 activation, we used the small molecule inhibitor bazedoxifene (BZA), which blocks formation of the IL6 receptor-gp130 complex. Glioma stem-like cells (GSCs) are more tumorigenic and more resistant to therapy. STAT3 is a key driver of the expression of stem cell transcription factors, making it a therapeutically important target in GBM. We show that treating GSCs with BZA decreases their self-renewal capacity and the expression of GSC markers in vitro. Additionally, BZA crosses the blood-brain barrier and confers a survival advantage in an orthotopic syngeneic mouse model of GBM. Although IL6-STAT3 signaling is important for GSC survival, a therapeutic agent that inhibits this pathway without toxicity has yet to be identified. Our findings reveal a mechanism of sustained STAT3 signaling in GBM and reveal its role in GSC maintenance, and we identify BZA as a novel candidate for treating GBM.