FOXP3-activated KCNMB2-AS1 promotes clear cell renal cell carcinoma through the miR-744-3p/CD1D axis.

BACKGROUND: Long noncoding RNAs (lncRNAs) are key regulators in cancer progression. Among them, KCNMB2 antisense RNA 1 (KCNMB2-AS1) has been identified as an oncogenic lncRNA in several tumor types; however, its role in clear-cell renal cell carcinoma (ccRCC) remains largely unexplored. This study aimed to elucidate the expression profile, functional significance, and underlying molecular mechanisms of KCNMB2-AS1 in ccRCC. METHODS: The expression of KCNMB2-AS1 in ccRCC tissues and cell lines was analyzed using publicly available datasets, quantitative real-time PCR, and Western blotting. Functional assays including Cell Counting Kit-8, colony formation, wound healing, and Transwell migration/invasion tests along with in vivo xenograft experiments were performed to assess its biological effects. Mechanistic studies, including luciferase reporter, chromatin immunoprecipitation (ChIP), RNA immunoprecipitation (RIP), and rescue assays, were conducted to verify the regulatory interactions among KCNMB2-AS1, forkhead box protein 3 (FOXP3), microRNA-744-3p (miR-744-3p), and cluster of differentiation 1D (CD1D). RESULTS: KCNMB2-AS1 expression was markedly elevated in ccRCC tissues compared to adjacent normal tissues, and its high expression was significantly associated with advanced tumor stage, presence of distant metastasis, and poor overall survival. Silencing KCNMB2-AS1 markedly suppressed ccRCC cell proliferation, migration, and invasion in vitro, accompanied by reduced epithelial-mesenchymal transition marker expression. Consistent with these findings, xenograft experiments confirmed that KCNMB2-AS1 knockdown attenuated tumor growth in vivo, while its overexpression promoted aggressive tumor behavior. Mechanistically, FOXP3 directly bound to the promoter region of KCNMB2-AS1, activating its expression transcriptionally. KCNMB2-AS1 acted as a molecular sponge for miR-744-3p, thereby relieving its inhibitory effect on CD1D expression. Rescue assays demonstrated that restoring CD1D expression counteracted the inhibitory phenotypes resulting from KCNMB2-AS1 silencing. CONCLUSION: KCNMB2-AS1 serves as an oncogenic lncRNA in ccRCC, functioning through a FOXP3/KCNMB2-AS1/miR-744-3p/CD1D signaling axis, thereby revealing a novel molecular pathway that contributes to ccRCC progression.