Autophagy and Bcl-2/BNIP3 death regulatory pathway in non-small cell lung carcinomas

We recently showed that non-small cell lung carcinomas (NSCLCs) are of dismal prognosis when encompassing accelerated autophagic activity. The regulation of this abnormally functioning degradation system and its association with hypoxia and apoptosis in lung carcinoma patients is unexplored. In this study we used 115 NSCLC tissues to examine the immunohistochemical expression of four distinct molecules - the major regulator of autophagy Beclin 1, the anti-apoptotic and anti-autophagic protein Bcl-2, the pro-apoptotic and pro-autophagic protein BNIP3, and a marker of hypoxia and glucolysis, the glucose transporter Glut 1. Most cases showed reduced reactivity for Beclin 1 (62%) and Bcl-2 (82%) proteins, almost half of our sample revealed strong BNIP3 expression (57%), whereas most of the carcinomas strongly expressed Glut 1 antigen (71%). Beclin 1 expression showed no association with survival. Bcl-2 positivity was a marker of good prognosis (p=0.04), whereas BNIP3 (p=0.0004) and Glut 1 (p=0.03) expression correlated with poor outcome in Stage I disease. Autophagic status was negatively associated with Bcl-2 (p=0.0006), but positively with Glut 1 expression (p=0.001). In conclusion, the accelerated autophagic status in NSCLC is unrelated to Beclin 1 and BNIP3 expression, but does show significant association with Bcl-2 reactivity. Furthermore, we showed important correlations between glucolysis and autophagy, guiding new pathways in future lung carcinoma research.