Background: The natural history of pancreatic carcinoma is characterized by rapid growth, local invasion and metastases. These processes are in part modulated through the equalibrium between matrix metalloproteinases (MMP) and their physiologic inhibitor (TIMP1) while another cytokine, hepatocyte growth factor (HGF) has been shown to be important in the generation of hepatic metastases in colorectal carcinoma. We have recently demonstrated the presence of the HGF receptor (HGF-R or c-met) and the cytokine receptors of interleukin-4 (IL-4R) and interleukin-2 receptor g (IL-2Rgc) on human pancreatic carcinoma cell lines. The hypothesis was that the growth and tissue invasion of these cells may be modulated through common signal pathways induced by the MMP and cytokine receptors IL-4R and IL-2Rgc.
Methods: Eight human pancreatic cell lines (CRL 1420, CRL 1469, CRL 1682, CRL 1687, CRL 2000, CRL 2110, HTB 79, and HTB 134 obtained from American Type Culture Collection, Manassa, VA) were screened for the presence of c-met and the IL-4R and IL-2Rgc. Expression of gene products were measured by RT-PCR and western blot analyses. Cell proliferation was determined by MTS assay and protein expression by western blot (including MMP 1,2,3 and 9 and TIMP 1). Invasion was determined by Matrigel membranes.
Results: Seven (88%) of the 8 cell lines expressed the c-met gene product by RT-PCR (using specific primers) and protein receptors by western blot analyses. Five (71% )of the 7 cell lines expressed IL-4R, while 3 (43%) expressed both IL-4R and IL-2Rgc. HGF (0.1-10ng/ml) induced a dose-dependent growth stimulation of CRL 1687 and HTB 134 (up to 1.45x in the MTS assay )and increase in MMP9 expression (western blot)with almost complete (85%) reversal of growth in the presence of IL-4 (1-1000 u/ml). The remaining MMP (1,2, and 3)and TIMP1 were uneffected by HGF or IL-4 or this combination. Increasing concentrations of HGF (0.1-10 ng/ml) induced greater (p<0.05) migration of CRL 1687 throught the Matrigel (200±70 to 320±100 cells/HPF) that was markedly reduced (70%) in the presence of IL-4 1000 u/ml.
Conclusions: Our results demonstrate an induction of pancreatic cell line growth and tissue invasion in c-met receptor positive cell lines by HGF with almost complete reversal of growth, tissue invasion and MMP9 expression by IL-4. The results of these studies demonstrate a potential mechanism for a cytokine-induced strategy for the prevention of metastases in select pancreatic carcinoma.