Correlation between BRCA1 and TopBP1 protein expression and clinical outcome of non-small cell lung cancer treated with platinum-based chemotherapy.

Abstract

To investigate the correlation between protein expression of breast cancer susceptibility gene 1 (BRCA1) and topoisomerase IIβ-binding protein 1 (TopBP1) and clinical outcome of non-small cell lung cancer treated with platinum-based chemotherapy. Immunohistochemical staining was conducted to detect the protein expression of BRCA1 and TopBP1 in 101 cases of NSCLC and to correlate these with clinical features, disease progression, and patient survival. Chi-square test (χ (2)-test) was used to evaluate categorical variables. Spearman's rank order correlation was used to analyze continuous variables. Overall survival rate of NSCLC patients was analyzed by Kaplan-Meier survival curve and log-rank test. Relevant factors affecting the survival of patients with advanced NSCLC were analyzed by COX proportional hazards regression model. A total of 101 NSCLC patients were included in the present study. In tumor tissue specimens, positive expression rates of BRCA1 and TopBP1 proteins were 51.5 and 57.4%, respectively. A significant correlation between the positive expression of BRCA1 and the positive expression of TopBP1 was observed (P<0.001, r=0.326). No significant correlation between BRCA1/TopBP1 and age, gender, smoking status, performance status score, pathohistological type, or clinical stage was detected (P>0.05). During the follow-up period, 65 patients died, and 86 patients showed progression at the end of the study. The survival rate of patients with negative BRCA1 protein expression was higher than that in patients with positive BRCA1 protein expression [median overall survival (OS) 34 vs. 21months, HR 1.913, 95% CI 1.161-3.150, P=0.011]. Similarly, the survival rate of patients with negative TopBP1 expression was higher than that in patients with positive TopBP1 (median OS 36 vs. 23months, HR 1.931, 95% CI 1.157-3.224, P=0.012). No significant correlation between protein expression of BRCA1 or TopBP1 with NSCLC disease progression was observed (P>0.05). The present study indicates NSCLC patients with negative BRCA1 and TopBP1 expression showed better prognosis than those with positive protein expression.