Oroxylin A increases the sensitivity of temozolomide on glioma cells by hypoxia‐inducible factor 1α/hedgehog pathway under hypoxia

• Published in: Journal of cellular physiology 2019-10, Vol.234 (10), p.17392-17404
• Main Authors: Wei, Mian, Ma, Rong, Huang, Shaoliang, Liao, Yan, Ding, Youxiang, Li, Zhaohe, Guo, Qinglong, Tan, Renxiang, Zhang, Lulu, Zhao, Li
• Format: Article
• Language: English
• Subjects: Autocrine signalling; Deactivation; Drug resistance; Flavonoids; Glioma; Glioma cells; hedgehog; Hedgehog protein; HIF‐1α; Hypoxia; Inactivation; Nuclei (cytology); oroxylin A; resistance; Secretion; Sensitivity; Signal transduction; Temozolomide; Transplantation; VHL protein; Xenografts; Xenotransplantation
• ISSN: 0021-9541; 1097-4652
• DOI: 10.1002/jcp.28361

Microenvironmental hypoxia‐mediated drug resistance is responsible for the failure of cancer therapy. To date, the role of the hedgehog pathway in resistance to temozolomide (TMZ) under hypoxia has not been investigated. In this study, we discovered that the increasing hypoxia‐inducible factor 1α (HIF‐1α) activated the hedgehog pathway in hypoxic microenvironment by promoting autocrine secretion of sonic hedgehog protein (Shh), and then upregulating transfer of Gli1 to the nucleus, finally contributed to TMZ resistance in glioma cells. Oroxylin A (C16H12O5), a bioactive flavonoid, could induce HIF‐1α degradation via prolyl‐hydroxylases–VHL signaling pathway, resulting in the inactivation of the hedgehog. Besides, oroxylin A increased the expression of Sufu, which is a negative regulator of Gli1. By this mechanism, oroxylin A sensitized TMZ on glioma cells. U251 intracranial transplantation model and GL261 xenograft model were used to confirm the reversal effects of oroxylin A in vivo. In conclusion, our results demonstrated that HIF‐1α/hedgehog pathway conferred TMZ resistance under hypoxia, and oroxylin A was capable of increasing the sensitivity of TMZ on glioma cells in vitro and in vivo by inhibiting HIF‐1α/hedgehog pathway and depressing the activation of Gli1 directly. we found that the increasing HIF‐1α activated the hedgehog pathway in the hypoxic microenvironment, finally contributed to TMZ resistance in glioma cells. Oroxylin A (C16H12O5), a bioactive flavonoid, could sensitize TMZ by inducing HIF‐1α degradation and increasing the expression of Sufu. Oroxylin A could be a potential resistance reversal agent for glioma chemotherapy.