IRX2 regulates endometrial carcinoma oncogenesis by transcriptional repressing RUVBL1

Endometrial carcinoma (EC) is a rising concern among gynecological malignancies. Iroquois Homeobox 2 (IRX2), a member of the Iroquois homeobox gene family, demonstrates variable effects in different cancer types, emphasizing the need for extensive exploration of its involvement in EC progression. Utilizing TCGA and GEO databases, as well as performing immunohistochemistry (IHC) analysis on clinical samples, we assessed the expression levels of IRX2 and its promoter methylation in EC. To understand the functional roles of IRX2, we conducted various assays including in vitro CCK-8 assays, colony formation assays, cell invasion assays, and cell apoptosis assays. Moreover, we utilized in vivo subcutaneous xenograft mouse models. Additionally, we performed KEGG pathway and gene set enrichment analyses to gain insights into the underlying mechanisms. To validate the regulatory relationship between IRX2 and RUVBL1, we employed chromatin immunoprecipitation and luciferase reporter assays. Our results indicate significantly reduced levels of IRX2 expression in EC, correlating with higher histological grades, advanced clinical stages, and diminished overall survival. We observed that DNA methylation of the IRX2 promoter suppresses its expression in EC, with cg26333652 and cg11793269 playing critical roles as methylated sites. In contrast, ectopic overexpression of IRX2 substantially inhibits cell proliferation and invasion, and promotes cell apoptosis. Additionally, we discovered that IRX2 exerts negative regulation on the expression of RUVBL1, which is upregulated in EC and associated with a poorer prognosis. In conclusion, our findings indicate that decreased expression of IRX2 facilitates EC cell growth through the regulation of RUVBL1 expression, thereby contributing to the development of EC. Hence, targeting the IRX2-RUVBL1 axis holds promise as a potential therapeutic strategy for EC treatment.