PABPC1L promotes tryptophan metabolism and immune suppression by stabilizing IDO1 in renal cell carcinoma [RIP-seq]

The tumor microenvironment (TME) in renal cell carcinomas (RCC) is marked by substantial immunosuppression and immune resistance though highly infiltrated by T cells. There is an urgent need to elucidate tumor immune evasion and to develop novel therapeutic target to boost the efficacy of immune checkpoint blockade (ICB) in RCC. Our study uncovers a mechanism wherein the polyadenylate-binding protein PABPC1L modulates indoleamine2, 3dioxygenase1 (IDO1), a prospective candidate for immunotherapy. PABPC1L, markedly upregulated in RCC, correlates with unfavorable prognosis and resistance to ICB. Overexpressed PABPC1L bolsters tryptophan metabolism and induces T-cell dysfunction by stabilizing IDO1. Conversely, silencing PABPC1L diminishes IDO1 expression, mitigates cytotoxic T-cell suppression, and enhances responsiveness to anti-PD-1 therapy. Our findings underscore PABPC1L's crucial role in facilitating immune evasion in RCC, making it a potential addition to ICB therapy. RIP-sequencing of total RNA of 769-P cells which was immunoprecipited by anti-PABPC1L RIP-INPUT vs RIP-PABPC1L