Ghrelin promotes pancreatic adenocarcinoma cellular proliferation and invasiveness

Abstract

Introduction: Ghrelin, a newly described 28 amino acid peptide hormone, has potent orexogenic properties that are of interest in developing novel therapies for cancer cachexia. We tested the hypothesis that pancreatic adenocarcinoma, commonly associated with marked cachexia, is a ghrelin-responsive malignancy. Methods: PANC1, MIAPaCa2, BxPC3 and Capan2 pancreatic adenocarcinoma cells were cultured in the presence of 1 to 100nM ghrelin or control vehicle (PBS). Proliferation was determined at 4 days by cell counting and MTT assay. Expression of ghrelin and the functional ghrelin 1a receptor was determined by RT-PCR and Western blot analysis. The effect of 10nM ghrelin on invasiveness was quantified in an 8μm pore Matrigel Boyden chamber assay and normalized to proliferation. Phosphorylation of Akt, a signal transduction molecule associated with pancreatic cancer invasiveness, was assessed using phospho-Akt (pAKT)-specific immunoblotting, and normalized to total Akt. Results: All cell lines expressed ghrelin 1a receptor mRNA and protein but none expressed ghrelin. Ghrelin treatment increased cellular proliferation (see graph, mean ± SD relative to control) and, at 10nM, increased cellular invasiveness (PANC1: 60 ± 5%, MIAPaCa2: 35 ± 3%, BxPC3: 30 ± 3% Capan2: 15 ± 3%. Mean % increase ± SD. P < 0.05) relative to control. Activating phosphorylation of Akt was increased by 10nM ghrelin in all cell lines. Conclusion: Pancreatic adenocarcinoma is a ghrelin-responsive malignancy. The use of ghrelin as a treatment for pancreatic cancer cachexia will require cautious evaluation.