Low expression of RBMS3 and SFRP1 are associated with poor prognosis in patients with gastric cancer.

RNA binding motif, single stranded interacting protein 3 (RBMS3) has been reported as a tumor suppressor gene (TSG) in some squamous carcinoma. However, its expression levels and clinical significance in gastric cancer (GC) remains unclear. Secreted frizzled-related protein 1 (SFRP1) plays a role of tumor suppressor in many cancers by inhibiting Wnt/β-catenin pathway. Nevertheless, its expression levels and clinical significance in GC are in dispute. In this study, quantitative real-time PCR and Western Blot were used to measure the mRNA and protein level of RBMS3 and SFRP1 in 23 fresh GC and corresponding normal tissues. Immunohistochemistry assay was performed to further measure the protein level of RBMS3 and SFRP1 on population-based tissue microarrays consisting of 172 GC cases. We found that 69.57% (16/23) and 73.91% (17/23) GC tissues expressed remarkably lower RBMS3 than the matched normal tissues respectively in mRNA and protein levels. Similarly, 78.26% (18/23) and 65.22% (15/23) GC tissues expressed lower SFRP1 than the matched normal tissues respectively in mRNA and protein levels. Additionally, the low expression of RBMS3 and SFRP1 protein were all significantly related to the poor histological grades and prognosis (all P<0.05). In multivariate analysis, RBMS3 and SFRP1 co-expression status was independent prognostic factor for GC patients. Finally, the positive correlation between expression levels (mRNA and protein) of RBMS3 and SFRP1 was observed. Overall, RBMS3 and SFRP1 are both aberrantly low expressed in GC, and RBMS3 and SFRP1 co-expression is a potential prognosis predictor of GC.