Phosphorylated Bcl-2 and Mcl-1 as prognostic markers in small cell lung cancer

Abstract

BACKGROUND We hypothesized that the activated phosphorylated forms of proapoptotic Bcl-2 family of proteins is most relevant to small cell lung cancer (SCLC) biology. We therefore characterized pBcl-2 and pMcl-1 in pulmonary neuroendocrine tumors to better elucidate the role of these proteins in SCLC. METHODS We analyzed archival samples of pulmonary carcinoid, SCLC and large-cell neuroendocrine carcinoma (LCNEC) by immunohistochemistry (IHC). Association of protein expression with age, gender, smoking status, tumor type, stage and survival was assessed by Wilcoxon rank-sum test, Kruskal-Wallis test, Spearman rank correlation, and Cox regression model. RESULTS We employed 77 cases: carcinoid (21%), SCLC (53%) and LCNEC (26%); median age of 61.5 years, 75% Caucasians and 60% female. Carcinoid had lower median expression of Bcl-2 [0 (0 - 100) vs. 90 (0 - 300); p<0.001] and pBcl-2 [12.5 (0 - 255) vs. 190 (0 - 300); p