Targeting NF-kB/BCL-2 pathway increases apoptotic susceptibility to chemotherapy in pancreatic cancer

Abstract Introduction. Pancreatic cancer is resistant to the apoptotic effect of chemotherapy; this may be due to either intrinsic resistance or induced following exposure to chemotherapy. Activation of NF-kb has been observed following chemotherapy, though whether this plays a role in the induced resistance or what downstream target genes are involved remains unclear. We have previously shown that NF-kb transcriptionally regulates BCL-2, an anti-apoptotic protein, and that elevated levels of BCL-2 confers chemoresistance. Therefore, we hypothesized that inhibition of the chemotherapy-induced mechanisms of resistance including BCL-2 will increase susceptibility to standard chemotherapeutic agents. Methods. MIA-PaCa-2 pancreatic cancer cell lines were grown under normal conditions and treated with taxol. The promoter activity of NF-kb and BCL-2 were observed at various time points by measuring luciferase activity. Protein levels were examined using Western blot for NF-kb and BCL-2. Cells were then exposed to HA14-1, a small molecule inhibitor of BCL-2, which has been shown to induce apoptosis in leukemia cell lines both alone and in the presence of chemotherapy. Cells were grown with a combination of taxol and HA14-1. Florescence-activated cell sorting (FACS analysis) and cell viability studies were performed to assess induction of apoptosis. Results. The treatment of MIA-PaCa-2 cell with taxol induced a transient increase in NFK-B activity and a subsequent increase in BCL-2 transcription. This led to an increase in BCL-2 levels. When BCL-2 activity was directly blocked with HA14-1 alone and when combined with taxol there was a significant increase in apoptosis. Conclusions. Targeting chemotherapy-induced mechanisms, such as BCL-2, may provide an additional method to increase pancreatic cancer’s sensitivity to chemotherapeutic agents.