PABPC1L promotes tryptophan metabolism and immune suppression by stabilizing IDO1 in renal cell carcinoma

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. Overall design: RNA-sequencing (RNA-seq) of 769-P cells revealed substantial transcriptional alterations upon PABPC1L knockdown