Bax inhibitor-1 is overexpressed in non-small cell lung cancer and promotes its progression and metastasis

Bax inhibitor-1 (BI-1) is a novel anti-apoptotic protein. While the effect of BI-1 on apoptosis has been extensively studied, less is known about how BI-1 is related to oncogenesis and the progression, particularly, the invasion and metastasis of cancer. In this study, we investigated the expression and function of BI-1 in human non-small cell lung cancer (NSCLC). RT-PCR and immunohistochemistry were performed on clinical NSCLC samples to detect BI-1 expression. Northern blot and Western blot analysis were performed to detect BI-1 expression of in NSCLC cell lines. Cell proliferation and apoptosis were analyzed by flow cytometry. Our results showed that the overexpression of BI-1 was significantly related to oncogenesis of NSCLC (P < 0.05). Meanwhile, we identified a novel 5'end from normal lung-derived BI-1 transcript, different from any transcript deposit in the Genbank, but we detected no mutations in the coding sequence and the promoter region of BI-1 and no abnormal splicing of the alternative first exon. Ectopic expression of BI-1 changed the proliferation and apoptosis of AGZY83-a and Anip973 cells. In conclusion, BI-1 is overexpressed in NSCLC and promotes the progression and metastasis of NSCLC.