Decreased Beclin-1 expression is correlated with the growth of the primary tumor in patients with squamous cell carcinoma and adenocarcinoma of the lung.

Beclin-1 is a Bcl-2-interacting protein, and it may delay cell cycle progression and induce autophagy. The function and expression of Beclin-1 and Bcl-2 in squamous cell carcinoma and adenocarcinoma of the lung remain largely unknown. Herein, we investigated the expression of Beclin-1 and Bcl-2 in squamous cell carcinoma and adenocarcinoma of the lung. Tissue samples from 262 cases were used in this study. Immunohistochemical staining for Beclin-1 and Bcl-2 were conducted using a tissue microarray. In squamous cell carcinoma, Beclin-1 expression was strongly positive in 48 (28.6%) of 168 samples, it was moderately positive in 42 (25.0%) of 168 samples, and it was negative or weakly positive in 78 (46.4%) of 168 samples. In adenocarcinoma, Beclin-1 expression was strongly positive in 26 (27.7%) of 94 samples, it was moderately positive in 27 (28.7%) of 94 samples, and it was negative or weakly positive in 41 (43.6%) of 94 samples. Beclin-1 expression was inversely correlated with the tumor size and the primary tumor stage (pT) in both types of tumor. Especially, the TNM stage of adenocarcinoma was inversely correlated with Beclin-1 expression. Our results suggest that a progressively reduced Beclin-1 expression is correlated with the primary tumor growth of squamous cell carcinoma and adenocarcinoma of the lung.