Stimulation of either protein kinase C or RAS mediated signaling enhances mitogen activated protein kinase activity, which in turn, activates transcrip tion of COX 2. We have previously reported that PANC 1 CM enhances ERK 1/2 activation and growth of PSCs. We Erlotinib clinical speculate that a growth factor is responsible for these effects, however, our attempts to identify the can didate using receptor antagonists and immunoneutraliza tion have not been successful. Inhibition of ERK1/2 phosphorylation Inhibitors,Modulators,Libraries by U0126 prevented the PANC 1 CM stimulated increase in PSC COX 2 protein production. In previous studies U0126 alone had no effect on ERK1/2 or COX 2 expression. This suggests that the MAP kinase pathway plays a role in cancer induced stimulation of COX 2 in PSCs.

The reported biological consequences of COX 2 up regulation include growth stimulation inhi bition of apoptosis, increased metastatic potential and promotion of angiogenesis. Increased expression of COX 2 in PSCs by PANC 1 CM may contrib ute to tumor progression. Finally, the proliferation of PSCs was inhibited by treat ment with NS398, a Inhibitors,Modulators,Libraries COX 2 inhibitor. In pancreatic carcinomas, COX 2 is overexpressed and NS398 inhibits tumor growth. This COX 2 inhibitor alone has no effect on expression of COX 2 or ERK1/2 and shows no toxicity at the concentration used in the present studies. Recent studies have demonstrated a role for the COX 2 enzyme and PGE2 in the regulation of epithelial cell growth and angiogenesis. These properties will need to be studied further in pancreatic adenocarcinoma and stellate cells.

NS 398 has Inhibitors,Modulators,Libraries been previ ously shown to inhibit cell proliferation of colorectal carcinoma by inducing apoptosis in a COX 2 independ ent fashion. More studies are needed to confirm the mechanism of inhibition Inhibitors,Modulators,Libraries by NS398. Conclusion The COX 2 protein is up regulated in pancreatic stellate cells by pancreatic cancer conditioned media. The induc tion of COX 2 by pancreatic cancer cells is mediated by extracellular signal regulated kinases 1/2. The COX 2 induction by pancreatic cancer cells is involved in mediating PSC proliferation. Therefore, COX 2 may play an important role in the regulation of desmoplasia in pancreatic cancer and inhibition of this enzyme may pre vent or reduce this response. Materials and methods Materials Iscoves modified Dulbeccos medium, Dul beccos modified Eagles medium, albumin, and pronase were purchased from Sigma Chemical.

Fetal bovine serum, glutamine, and antibiot ics were purchased from Mediatech, Inc. Collagenase P was purchased Inhibitors,Modulators,Libraries from the Roche Diagnostics Corporation, and deoxyribonuclease from Amersham Biosciences. Nycodenz was obtained from Nycomed Pharma AS. U0126, a specific inhibitor of extracellular signal regu lated kinase activation, was obtained from Calbio chem. NS398, COX 2 inhibitor was obtained from Cayman Chemicals. 3H methyl thymidine was purchased from Vorinostat cost ICN Pharmaceuti cals.