Integrative multi-omics analysis identifies SMIM24 as a favorable prognostic biomarker in clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) exhibits substantial molecular and clinical heterogeneity, contributing to variable disease progression and therapeutic outcomes. We previously identified a de-clear cell differentiation (DCCD) tumor state characterized by loss of canonical clear-cell features and aggressive clinical behavior. This study aimed to translate DCCD-associated biology into a prognostic framework and investigate its underlying molecular basis. Using TCGA-KIRC as the training cohort, we developed a five-gene prognostic signature comprising COL7A1, IGFN1, AJAP1, SMIM24, and ADGRV1, which consistently stratified patient survival across multiple public and institutional cohorts. Comparison with SSIGN, Leibovich, and ClearCode34-like models demonstrated that the DCCD signature provided complementary prognostic information. High-risk tumors exhibited enhanced proliferative and invasive programs, increased IL6-JAK-STAT3 pathway activity, and an immune-excluded microenvironment. Associations with treatment response were also observed in retrospective therapeutic cohorts. Integrated analyses of bulk and single-cell transcriptomics, spatial transcriptomics, tissue microarrays, CPTAC proteomics, and molecular interaction networks identified SMIM24 as an epithelial-associated factor linked to favorable outcomes and preserved metabolic programs. Functional experiments showed that SMIM24 overexpression suppressed migration, invasion, three-dimensional spheroid invasion, and clonogenic growth in ccRCC cells, accompanied by reduced JAK1 and STAT3 phosphorylation and decreased PD-L1 expression. Pharmacological activation of STAT3 with Colivelin partially restored PD-L1 expression in SMIM24-overexpressing cells. Collectively, these findings support the reproducibility of the DCCD-associated prognostic framework and identify SMIM24 as a candidate suppressor of ccRCC aggressiveness and PD-L1 expression, potentially acting in part through reduced STAT3 activation.