Loss of CSMD1 or 2 may contribute to the poor prognosis of colorectal cancer patients.

CUB and sushi multiple domain protein 1 (CSMD1) is a candidate tumor suppressor gene. The three members of CSMD family have very similar structures, each consisting of 14 CUB domains separated from one another by a sushi domain, an additional uninterrupted array of sushi domains, a single transmembrane domain, and a short cytoplasmic tail. In this work, we aimed to study the protein and mRNA levels of the CSMD1, CSMD2, and CSMD3 and evaluate their prognostic importance in colorectal cancer. Reduced expressions of these three proteins were detected in colorectal cancer tissues by comparing matched normal tissues. Low CSMD2 expression was significantly associated with differentiation, lymphatic invasion, and tumor size. CSMD3 was associated with differentiation and lymphatic invasion. CSMD1 and CSMD2 expressions were associated with overall survival. This study offers convincing evidence for the first time that the three genes of CSMD family were downregulated in the patients with colorectal cancer and may be used as predictors of colorectal cancer.