179 - 12-HETE Regulates Stromal Aging Induced Proliferation of Pancreatic Cancer Cells

Abstract

Recent evidence suggests a significant role of fibroblasts in pancreatic ductal adenocarcinoma (PDAC) stromal cellularity, metabolism, and therapy response. Considering PDAC being an age-associated disease and a dismal 5-y survival of less than 6%, this study investigates whether stromal aging regulates PDAC progression. Results showed that normal human fibroblasts (NHFs) from older vs. younger healthy individuals stimulate proliferation of PDAC cells in co-cultures and PDAC cells that were cultured in conditioned media. Results from 3D experiments also showed a significant acceleration in proliferation of luciferase expressing MIA PaCa-2 PDAC cells co-cultured with old vs. young NHFs. These results were also recapitulated from in vivo tumor xenograft experiments: (i) 2x tumor volume in xenograft of MIA PaCa-2 cells and old NHFs; and (ii) median survival of 32 d in mice carrying xenograft of MIA PaCa-2 cells and old NHFs vs. 44 d in mice carrying xenograft of MIA PaCa-2 cells and young NHFs. Results from oxidative stress PCR-array (SA Bioscience) and RT-PCR assays showed 6-fold increase in arachidonic acid lipoxygenase (ALOX12) expression in old vs. young NHFs, which was also associated with increases in ALOX12 metabolite, 12-(S)-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE): 8 in old vs. 1 femto g/cell in young NHFs. Oncomine data search and RT-PCR analysis showed a lack of ALOX12 expression in PDAC cells, suggesting that PDAC rely on stromal derived mitogens for their proliferative needs. Consistent with this hypothesis, 12-HETE stimulated MIA PaCa-2 proliferation, and siRNA knockdown of ALOX12 in old NHFs suppressed MIA PaCa-2 proliferation in co-cultures. In summary, these results showed that stromal aging significantly contributes to PDAC progression, and identified 12-HETE as a potential biomarker for PDAC progression and target for therapy.