Overexpression of Bax inhibitor-1 (BI-1) induces cell transformation in NIH3T3 cells

BI‐1 (Bax inhibitor‐1), an apoptosis‐inhibiting gene belonging to the Bcl‐2 protein family, plays an important role in mitochondrial apoptosis pathway to suppress Bax‐induced apoptosis. To investigate the potential role of BI‐1 in promoting cell growth and tumorigenesis, in the present study we overexpressed the BI‐1 gene in NIH3T3 cells using the lentivirus‐mediated gene expression system. Our in vitro studies showed that NIH3T3 cells overexpressing BI‐1 displayed a significantly higher growth rate and formed more and larger colonies than the control cells. In addition, our in vivo studies indicated that the lenti‐BI‐1‐infected cells formed obvious tumours, while no tumours were formed by the control cells after subcutaneously injected into nude mice. These results strongly suggested that the BI‐1 gene might play a crucial role in neoplastic genesis and development.