Abstract 3640: RAB26 accelerates endometrial cancer cell progression by regulating the Hedgehog signaling pathway

Abstract As one of the most common gynecological malignant tumors, endometrial cancer (EC) is continuously being studied since its etiology is still not clear. RAB26, a member of the RAB family, has been shown to influence cell proliferation, metastasis and other malignant phenotypes in several cancers. However, whether and how RAB26 plays roles in EC remain unknown. Our previous study showed that RAB26 was related to the cell cycle-associated protein IK, which has been shown to contribute to carcinogenesis. Herein, we further explored the clinical significance and biological function of RAB26 in EC. Immunohistochemical staining of 615 endometrial tissue samples was conducted to explore whether RAB26 expression was related to the clinicopathological characteristics of EC. In vitro and in vivo experiments were used to evaluate the role of RAB26 in EC and investigate the underlying mechanism. RAB26 expression was higher in EC than in normal endometrium (NE), hyperplastic endometrium (HE) and atypical hyperplastic endometrium (AHE). High RAB26 expression was positively correlated with tumor histological grade (P=0. 010), FIGO stage (P=0. 042) and tumor size (P=0. 003) in EC. RAB26 attenuation inhibited cell proliferation and metastasis but promoted cell apoptosis and caused G0/G1 arrest. After RAB26 attenuation, RNA sequencing data showed that the Hedgehog signaling (SHH) pathway was enriched. Further western blot results confirmed that the levels of SHH pathway proteins (SHH, PTCH1, smo and Gli1) decreased as RAB26 expression was attenuated. Moreover, an agonist of the SHH pathway, purmorphamine, blocked the inhibitory effect of RAB26 attenuation on EC progression. The results of an in vivo study also showed that RAB26 attenuation exerted a significant antitumor effect. Accordingly, RAB26 may act as an oncogenic protein to promote EC progression through the SHH pathway. RAB26 may be a potential target for the treatment of EC patients. Citation Format: Chao Gao, Yanyan Liu, Yanyan Han, Fengxia Xue, Yingmei Wang. RAB26 accelerates endometrial cancer cell progression by regulating the Hedgehog signaling pathway abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3640.