Targeting NF-κB Signaling in Pancreatic Cancer Associated Fibroblasts with Bortezomib
A critical component of the pancreatic tumor microenvironment is cancer associated fibroblasts (CAFs), which is largely responsible for producing extracellular matrix proteins to form a physical barrier that prevents conventional therapies from targeting the tumor. Therefore, understanding the exact role of CAFs is crucial to developing viable therapies. The rate of cancer metastasis and patient survival has been reported to be correlated with CAF expression of CD146; siRNA knockdown of CD146 in CAFs in vitro increases tumor cell migration in co-culture systems, and patients who are CD146 negative in their CAFs have shorter periods of remission post-treatment. In this study we aimed to increase CD146 expression in CAFs by inhibiting NF-κB with bortezomib, a drug that prevents a proteasome from degrading NF-κB’s inhibitor IkBα. To do this, SRB drug-cytotoxicity assays were first performed to determine bortezomib’s IC50 values for every cell line in the study. Then cells were treated with the IC50 in six-well plates, and their protein lysates were analyzed in western blotting to determine the changes in protein expression. Treatment with this drug lead to a decrease in the p50 subunit of NF-κB in two CAF cell lines, but in normal stellate cells the p50 level increased. We are currently troubleshooting the detection of CD146 on the western blots, and we plan on increasing the protein amount in each well and including more positive controls such as kidney tissue. We will also include multiple myeloma and pancreatic cancer cell lines to aid our study of bortezomib’s effects on NF-κB expression. NF-κB also regulates the secretion of inflammatory and growth factors, which CAFs utilize to modulate the tumor microenvironment. We will therefore also probe for the effects of bortezomib on CAFs and their production of immune modulatory cytokines such as CCL5, which will allow us to examine their effects on the immune response in animal models.