Effectors Implicated in the Adenylyl Cyclase 1 Inhibitory Effect on Cell Proliferation and Migration in Pancreatic Cancer Cells

Abstract

Pancreatic adenocarcinoma is among the most aggressive of all cancers in the United States. Cyclic adenosine monophosphate (cyclic AMP) is a second messenger that regulates the proliferation and migration of pancreatic cancer cells. Cyclic AMP is formed from cytosolic ATP by the enzyme adenylyl cyclase (AC). In the presence of forskolin, a transmembrane AC activator, the proliferation and migration of pancreatic cells have been inhibited. Since the mechanisms underlying the inhibitory effect of activated adenylyl cyclase is little understood, we investigated the downstream mediators implicated in the AC/cyclic AMP pathway. With this purpose, we overexpressed AC1 in the human pancreatic adenocarcinoma (HPAC) cell line, and through the protein kinase A (PKA) inhibitor H-89 and the exchange protein directly activated by cyclic AMP (EPAC) inhibitor ESI-09, we assessed the effector involved upon the treatment with forskolin. We were able to successfully overexpress the AC1 using the plasmid pCMV-SPORT6 containing the insert human ADCY1 cDNA, which encodes the AC1 protein. Through the utilization of the MTT Cell Proliferation Assay Kit, we found that H-89 (inhibitor of PKA) counteracts the inhibitory effect of forskolin, however ESI-09 (inhibitor of EPAC) does modify this effect. Therefore, PKA alone mediates the inhibitory effect of forskolin/AC1/cyclic AMP on cell proliferation in HPAC cells. Further studies are underway to determine the cyclic AMP effector implicated in the inhibitory effect of forskolin on cell migration through utilization of the Cytoselect 24-Well Cell Migration Assay Kit.