Reduced tumor suppressor in lung cancer-1 expression is associated with a poor prognosis and its gene promoter methylation in colorectal adenocarcinoma

Abstract

Objective To investigate the expression of tumor suppressor in lung cancer-1 (TSLC-1) and its gene promoter methylation in colorectal adenocarcinoma,and evaluate its clinical signifi-cance.Methods Immunohistochemical Envision two-step technique was used to detect the expression of TSLC1 in primary colorectal adenocarcinoma; and the relationships between the expression of TSLC1 and clinical parameter including prognosis were analysed statistically.The promoter methylation of TSLC1 gene was detected by methylation-specific polymerase chain reaction.Results TSLC-1 protein expressing positive rate in primary colorectal adenocarcinoma was 41.51％ (22/53),which was obviously lower than that in paraneoplastic colorectal mucous (100％,20/20).Compared with TSLC-1 positive expressing group,group of TSCL-1 negative expressing showed higher lymph node metastasis rate and more advanced clinical stage (P ＜ 0.05).The median survival time in TSLC-1 negative expressing group was 32.22 months,significantly shorter as compared with TSLC-1 positive expressing group (47.55 months) (P ＜ 0.05).TSLC-1 gene promoter region was methylated in 13 of 31 (41.94％) colorectal adenocarcinomas without TSLC-1 protein expressing,that was higher significantly than that in the group of TSLC-1 protein positive expressing (2/22) and normal tissue adjacent to cancer (1/20) (P ＜ 0.05).Conclusion TSLC-1 protein expression was down-regulated in primary colorectal adenocarcinoma,and it was an important factor for predicting prognosis; the methylation-mediated inactivation of TSLC-1 maybe is main mechanism of TSLC-1 expressing down-regulation. Key words: Colorectal adenocarcinama; Tumor suppressor in lung cancer-1; Gene methylation