Co-expression of CMTM6 and PD-L1: a novel prognostic indicator of gastric cancer

Abstract Background CKLF Like MARVEL Transmembrane Domain Containing 6 (CMTM6) is involved in the epigenetic regulation of genes and tumorigenesis. Programmed cell death ligand 1 (PD-L1) is closely related to the prognosis of some human cancers. CMTM6 is a key regulator of PD-L1 in many cancers. The purpose of this study was to investigate the expressions of these proteins in gastric cancer and the correlations with clinicopathological features and survival. Methods The expression levels of CMTM6 and PD-L1 were examined in 185 gastric cancer specimens by immunohistochemistry. Chi-square test was used to analyze the relationship between CMTM6 and PD-L1 expressions and clinicopathological characteristics. Kaplan-Meier method and log-rank test were used to analyze the survival data of patients.Results The positive expression rates of CMTM6 and PD-L1 were 78.38% (145/185) and 75.68% (140/185), respectively. High expression of CMTM6 and PD-L1 was correlated with Borrmann type ( P < 0.001), N stage ( P = 0.002), peritoneal metastasis ( P = 0.007) and TNM stage ( P = 0.038). The expression of CMTM6 and PD-L1 in gastric cancer tissues was positively correlated (Pearson's coefficient test, r = 0.260; P < 0.001). High expression of CMTM6 was correlated with poor prognosis (HR = 1.668; 95% CI = 1.032–2.695; P = 0.037). High expression of both CMTM6 and PD-L1 could be used as an independent factor for overall survival (HR = 1.554; 95% CI = 1.011–2.389; P = 0.044). Conclusions The combined detection of CMTM6 and PD-L1 may be used as an indicator for judging the prognosis of gastric cancer.