Above observation that BC sensi tized lung cancer cells to gemcitabine led us to investi gate the effects of BC on NF B activity and Bfl 1 expression. As shown in Figure 4A, low dose gemcitabine induced Bfl 1 overexpression was inhibited by BC co treatment in A549 cells. Bfl 1 protein expres Calcitriol mechanism sion was also suppressed by BC. BC also down regulated the Bcl xL but increased the Bax expression. These data suggested that BC Inhibitors,Modulators,Libraries might alter the balance of Bcl 2 family proteins towards the pro apoptotic state, which includes down regulation of Bfl 1. We next assessed the effect of BC on NF B activity in A549 cells. BC treatment was found to reduce NF B activity to half its basal level. furthermore, NF B activity, which had been elevated by more than 3 fold by gemcitabine at 40 ng/ml, markedly declined to a very low level when cells were co treated with BC an.

gemcitabine. Immunoblotting also revealed that low dose gemcitabine caused the translocation of p65/relA from the cytoplasm to Inhibitors,Modulators,Libraries the nucleus, which was prevented by BC. These findings together suggest that BC might suppress NF B activity and subsequently down Inhibitors,Modulators,Libraries regulate Bfl 1, and thus, sensitizes lung cancer cells to gemcitabine induced cell death. However, it still remained unclear whether the BC induced down regulation of Bfl 1 caused the observed sensitization to gemcitabine or just was a coincidence. To address this, we examined whether Inhibitors,Modulators,Libraries the direct sup pression of Bfl 1 by siRNA could sensitize A549 cells to gemcitabine induced apoptosis.

It was found that whereas the direct down regulation of Bfl 1 had little effect on cell viability, Bfl 1 siRNA and gemcitabine co treatment increased apoptotic cell death. These data suggest that Bfl 1 might play a role in gemcitabine resistance Inhibitors,Modulators,Libraries of lung cancer cells, and that the down regulation of Bfl 1, either directly or using BC, offers an effective means of making lung cancer cells sensitive to gemcitabine. BC and low dose gemcitabine co treatment efficiently suppressed tumor growth and induced tumor cell death in a lung cancer xenograft model Finally, to evaluate the in vivo anti tumor effect of BC and low dose gemcitabine therapy, we established a human lung cancer xenograft model in nude mice using A549 cells as described in Materials and Methods. As shown in Figure 6, in mice treated with control adeno virus or gemcitabine, tumors reached mean volume of 2488 mm3 1282 mm3 at 30 days after the last treat ment. However, tumor growth was significantly Vandetanib VEGFR inhib ited in mice co treated with BC and gemcitabine. the average tumor volume was 380 97 mm3 at 30 days, which consistent with more than an 80% reduction in tumor weight.