M. A. Enman1, S. Daniels1, U. Vaish1, T. Jain1, S. Iyer1, P. Sahay1, S. Giri1, A. Gutierrez-Garcia1, V. Dudeja1 1University Of Alabama at Birmingham, Surgery, Birmingham, Alabama, USA
Introduction:
The Aryl Hydrocarbon Receptor (AhR) is a ligand-activated transcription factor that is upregulated in pancreatic ductal adenocarcinoma (PDAC). Activation of AhR pathways promote the activation of pancreatic stellate cells (PSCs), pancreatic fibrosis, proliferation of cancer cells, as well as evasion of immune surveillance. We set out to study the effects of AhR inhibition on PSCs and cancer associated fibroblasts (CAFs).
Methods:
Pancreatic stellate cells (PSC) were isolated from the pancreas of AhR knockout (AhR -/-), AhR wildtype (AhR +/+), C57/BL6 mice, and plated on plastic. A pharmacologic inhibitor (Bay2416964) was used to inhibit AhR in BL6 PSCs and cultured for 24 hours. Conditioned media from KPC (LSL-KrasG12D/-;LSL-Trp53R172H/-;Pdx1-Cre) cells was added for 4 hours prior to trypsinization. From each of these PSCs, RNA was eluted, cDNA was created, and RT-PCR was performed to investigate PSC activation and CAF markers.
Results:
Genetic and pharmacological inhibition of AhR resulted in downregulation of downstream markers of AhR, including CYP1B1 and AhRr in the PSCs. Furthermore, markers of PSC activation such as aSMA, Col1a, LIF, IL-6, IL-11, and FAP were also downregulated in PSCs with AhR inhibition. FAP, a global marker for CAFs, was downregulated in PSCs with AhR inhibition co-cultured with conditioned KPC media.
Conclusion:
The pancreatic cell stroma is important in fibrosis and inflammation, as well as the development, growth, and proliferation in tumor cells. AhR-inhibited PSCs do not have the characteristic desmoplastic stroma that is seen in wildtype and BL6 PSCs. Our findings suggest that AhR inhibition has a negative effect on the activation and proliferation of PSCs, as well as a negative effect on the production of CAFs, which are crucial to the growth and proliferation of PDAC tumor cells.