BackgroundWe investigated a 27-gene panel (Sig27), derived from prostate cancer, for risk stratification of RCC (clear cell RCC/ccRCC, papillary RCC/pRCC, and chromophobe RCC/chRCC).MethodsSig27 gene expressions were examined in 960 RCC and 201 kidney tissues. Sig27 was evaluated for predicting overall survival (OS), association with immune checkpoints (IC), regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSC), and tumor-associated macrophages (TAM) in RCC.ResultsSig27 robustly predicts OS of ccRCC, pRCC, and chRCC. Sig27 stratifies high-risk ccRCCs: median survival month (MSM) 19.3 and 80.4% of deaths and high-risk pRCCs (MSM 19.6 and 58.6% of death) compared to low-risk ccRCCs (2.9% of death) and pRCCs (2.7% of fatality). Sig27 contains several novel genes related to the RCC immunosuppressive features. FPR3, NOD2, MCTP1, LAMP3, TFEC, and FAM65B are highly correlated with MDSC, Treg, TAM and multiple (≥12) ICs in RCCs. FPR3 and NOD2 are pattern recognition receptors and initiate proinflammatory responses via sensing pathogen-associated molecular patterns and damage-associated molecular patterns; their upregulations may contribute to chronic inflammation in RCC. The Sig27 metagene is expressed in ccRCC-associated immune cells: exhausted CD8T cells, TAM, Treg, and others.ConclusionsSig27 is a novel and effective pan-RCC biomarker with high-level associations with RCC immunosuppressive features.