The Role of MCM7 and Its Hosted miR-106b-25 Cluster in Renal Cancer Progression

Renal cancer is among the deadliest human malignancies. MCM7, a cell cycle-regulating protein, is frequently overexpressed in cancers and is associated with hyperproliferation and cancer progression. miR-25-3p, miR-93-5p, and miR-106b-5p form the miR-106b-25 cluster, located within the MCM7 gene, and have previously been reported as upregulated in RCC. This study investigates whether miRNAs from the miR-106b-25 cluster regulate common target genes, enhance one another's effect, and act synergistically with MCM7 to promote tumor progression. Tissue samples from clear cell RCC (ccRCC) and paired controls were analysed to assess MCM7 expression and genes targeted by the miR-106b-25 cluster. Findings were further validated using the TCGA-KIRC dataset. Functional studies in RCC-derived cell lines were conducted to evaluate the effects of miRNAs on target gene expression, as well as MCM7, and the combined contributions of MCM7 and the miR-106b-25 cluster to renal cancer progression. We demonstrate that MCM7 is upregulated at both transcript and protein levels in RCC, contributing to cancer progression by regulating cell proliferation and caspase-3/7 activity. Furthermore, we identified cancer-related genes aberrantly expressed in ccRCC (BRMS1L, CPEB3, DNAJB9, KIF3B, NFIB, PTPRJ, RBL2) and targeted by members of the miR-106b-25 cluster, suggesting that their dysregulation may be driven by these miRNAs. Inhibition of the miR-106b-25 cluster increases caspase-3/7 activity. These findings demonstrate that both MCM7 and the miR-106b-25 cluster contribute to renal cancer progression.