RCAS1 is a promising therapeutic target against cancer: Its multifunctional bioactivities and clinical significance

Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is a type II membrane protein that can induce apoptosis in immune cells, including peripheral lymphocytes and natural killer cells, after being converted to a secreted type by ectodomain shedding. So far, over 140 scientific reports have been published concerning the biological functions and clinical significance of RCAS1. Since RCAS1 not only helps tumor cells to evade immune surveillance but also induces cancer stromal tissue remodeling, RCAS1 is believed to exaggerate aggressive characteristics of human malignancies. Clinically, RCAS1 expression correlates with several pathological variables including tumor size, stage and invasion depth, and lymph node metastasis, and is a negative predictor of overall survival in 15 different kinds of cancer. RCAS1 is secreted in significantly greater quantities in serum of pleural effusion in cancer patients than noncancer patients, and its level is changed in response to treatment. Novel therapeutic strategies against cancer are now under development by targeting the intriguing biomarker RCAS1.