Elevation of intracellular cyclic adenosine monophosphate inhibits the epidermal growth factor signal transduction pathway and cellular growth in pancreatic adenocarcinoma cell lines.
BACKGROUND
The epidermal growth factor (EGF) signal transduction pathway, frequently activated in pancreatic cancer, is an important regulator of cellular growth and transformation. This study examined whether activation of the cyclic adenosine monophosphate protein kinase A pathway may inhibit the EGF signal transduction pathway in pancreatic cancer cell lines.


METHODS
Human pancreatic cancer lines BxPC-3 and AsPC-1 were stimulated with EGF, forskolin, or both. Forskolin is a compound that increases cyclic adenosine monophosphate levels. Assays of cell lines were then obtained for cellular growth (MTT assay), anchorage-independent growth (soft agar), and EGF-induced mitogen-activated protein kinase activation as measured by an in-gel kinase assay.


RESULTS
Treatment with forskolin resulted in inhibition of EGF-induced activation of mitogen-activated protein kinase activity (BxPC-3 78% inhibition and AsPC-1 70% inhibition, p < 0.005), diminished cellular proliferation (BxPC-3 92% inhibition and AsPC-1 86% inhibition, p < 0.001), and formation of colonies in soft agar (BxPC-3 98% inhibition and AsPC-1 76% inhibition, p < 0.001). Forskolin did not inhibit EGF receptor autophosphorylation or tyrosine kinase signaling in response to EGF.


CONCLUSIONS
Forskolin-induced inhibition of mitogen-activated protein kinase is associated with diminished pancreatic cancer cell proliferation in vitro. Use of strategies to increase cyclic adenosine monophosphate levels may have therapeutic application in pancreatic cancer.
Lieberman
M D
MD
Department of Surgery, Cornell University Medical College-New York Hospital, NY., USA.
Paty
P
P
Li
X K
XK
Naama
H
H
Evoy
D
D
Daly
J M
JM
D000230:Adenocarcinoma; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D018929:Cell Culture Techniques; D002455:Cell Division / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000502:physiology*; D066246:ErbB Receptors / Q000378:metabolism; D006801:Humans; D010190:Pancreatic Neoplasms; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014407:Tumor Cells, Cultured / Q000737:chemistry / Q000166:cytology / Q000378:metabolism
D019000:Phosphotyrosine; D004815:Epidermal Growth Factor; D000242:Cyclic AMP; D066246:ErbB Receptors; D017871:Calcium-Calmodulin-Dependent Protein Kinases