RTP4 Suppresses Colorectal Cancer Progression via MHC-I-Mediated CD8+ T Cell Infiltration and Enhances Immunotherapy Response.

While RTP4 is known to regulate odorant receptor trafficking, its role in colorectal cancer (CRC) remains unclear. This study investigates the clinical relevance and functional mechanisms of RTP4 in CRC. Comprehensive analyses revealed significant downregulation of RTP4 expression in CRC tissues, correlating with poor patient prognosis. RTP4 expression showed strong associations with immune-related genes, biological processes and anti-tumour immune cell infiltration. Mechanistic studies demonstrated that RTP4 upregulates MHC-I expression, which enhances CD8+ T cell recruitment and strengthens anti-tumour immunity in both cellular and animal models. Furthermore, RTP4 overexpression markedly improved the efficacy of immune checkpoint blockade therapy. All in all, our findings establish RTP4 as a dual-functional biomarker for prognosis prediction and a potential target to enhance immunotherapy responsiveness in CRC.