Abstracts
1997 Digestive Disease Week

Human pancreatic carcinoma growth and invasion is regulated by c-met and interleukin-4 receptor gene expression.

MC Kelley, TX Nguyen, DSB Hoon, R Essner. The John Wayne Cancer Institute Santa Monica, CA.

The natural history of Pancreatic Carcinoma (PC) is characterized by local invasion and rapid tumor progression, but little is known about the molecular mechanisms which regulate these processes. Hepatocyte Growth Factor (HGF) and Interleukin-4 (IL-4) regulate colon carcinoma growth, migration and invasion via their high affinity receptors, c-met gene product (HGFR) and IL-4R (J. Cell Biochem 62:443, 1996). This study evaluates c-met and IL-4R gene expression in human PC and the role of their ligands, HGF and IL-4 in regulating the growth, migration and invasion of PC in vitro. A panel of 8 human PC cell lines was evaluated for c-met and IL-4R gene expression by RT-PCR and western blot. 5 of 8 lines expressed both c-met and IL-4R at the mRNA and protein level. Three lines expressing high levels of c-met and IL-4R (ASPC-1, BXPC-3, CFPAC-1) were evaluated for proliferation (MTS assay), migration (through uncoated transwells) and invasion (through Matrigel^{R} coated transwells) in response to HGF (0.1-10 nM), IL-4 (1-1000 U/ml) or both. After 5 days HGF (10 nM) induced up to a 50% increase in proliferation which was completely inhibited by IL-4 (1000 U/ml). Migration and invasion increased 2 to 4 fold in all 3 lines after treatment with HGF (10 nM) for 72 hours, and IL-4 (1000 U/ml) inhibited this response. IL-4 alone did not effect proliferation, migration or invasion or have direct toxic effects. Tumor cell invasion is regulated by the balance of matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinases (TIMP) production. To determine the mechanism underlying the increased invasion, the supernatant of PC cells cultured in the presence of HGF (10 nM) or IL-4 (1000 U/ml) was evaluated for expression of MMP and TIMP by ELISA (MMP-1, TIMP-1) and western blot (MMP-2,3,9 and TIMP-2). All 3 cell lines produced detectable levels of each MMP and TIMP except TIMP-2. HGF induced a 2-fold increase in MMP-9 production which was completely abrogated by IL-4. IL-4 alone did not change MMP-9 levels, and MMP 1,2 and 3 and TIMP-1 production was not significantly altered by HGF or IL-4. We conclude that the c-met and IL-4R genes are frequently expressed in PC. HGF stimulates growth, migration, invasion and MMP-9 production by PC cell lines which can be blocked by IL-4. The expression of c-met and IL-4R genes may be important for PC growth and invasion in vivo, and their signal transduction pathways represent potential targets for novel therapeutic strategies for this disease.