Objective: The peptide hormones guanylin and uroguanylin and their receptor, guanylate cyclase C (GC-C), are expressed in pancreatic duct cells. In colon cancer, guanylin peptides are shown to exert strong anti-tumor activity through the GC-C pathway. The objective of this study was to analyze the role of guanylin and uroguanylin in human pancreatic cancer.
Material and methods: Quantitative real-time polymerase chain reaction (QRT-PCR) was used to show the expression of guanylin, uroguanylin and GC-C in specimens of human pancreatic cancer, chronic pancreatitis donor and in pancreatic tumor cell lines. The presence of guanylins and GC-C in tumor cell lines and in pancreatic cancer tissues was shown by immunofluorescence and immunohistochemistry. The effect of guanylin and uroguanylin on cell cycle and cell death of pancreatic cancer cells was investigated by fluorescence activated cell sorter (FACS) analysis using annexin and propidium iodide. In addition, the growth inhibitory effect of guanylins on pancreatic cancer cells was assessed using the MTT assay.
Results: Guanylin, uroguanylin and GC-C were expressed at mRNA and protein levels in pancreatic cancer and cancer cell lines. As shown by QRT-PCR, GC-C expression was significantly up-regulated in pancreatic cancer compared with that in healthy pancreatic tissues (p<0.00001) and chronic pancreatitis (p<0.05). Guanylin and uroguanylin were not up-regulated in pancreatic cancer. The MTT assay revealed significant inhibition of pancreatic cancer cell proliferation by uroguanylin in a dose-dependent fashion, whereas Panc1 and Capan1 cell lines were significantly inhibited already at the lowest uroguanylin concentration (2 nM, p<0.05).
Conclusions: Our data suggest therapeutic properties of uroguanylin in pancreatic cancer via GC-C-dependent mechanisms. In addition, determination of GC-C expression might be a useful marker for differentiation between pancreatic cancer and chronic pancreatitis.