Bag3 promotes resistance to apoptosis through Bcl-2 family members in non-small cell lung cancer

In non-small cell lung cancer (NSCLC) certain molecular characteristics, which are related to molecular alterations have been investigated. These are responsible for both the initiation and maintenance of the malignancy in lung cancer. The aim of this study was to evaluate the influence of Bag3 (Bcl-2 associated athanogene 3) in the regulation of apoptosis on NSCLC. Bag3 and Hsp70 expression were examined by immunohistochemistry to confirm their potential roles in the prevalence of NSCLC. We also established human normal bronchial epithelial cells and HOP-62 cell line as the model to analyze cell apoptosis and the expression of Hsp70, Bcl-XL and Bcl-2, which were affected by Bag3. In this study, we found that Bag3 and Hsp70 are highly expressed in few tissues and cell lines of NSCLC. Bag3 inhibits apoptosis in human normal bronchial epithelial cell lines and sustain the survival of NSCLC cells. Bag3, Hsp70, Bcl-XL and Bcl-2 are up-regulated in NSCLC cell lines. At the same time, the silencing of Bag3 results in diminishing protein levels of Bcl-XL and Bcl-2. The results of immunoprecipitation identified that Bag3 could interact with Hsp70, Bcl-XL and Bcl-2 NSCLC cells directly or indirectly. We conclude that NSCLC cells were protected from apoptosis through increasing Bag3 expression and consequently promoted the expression of Bcl-XL and Bcl-2.