Effects and mechanisms of pancreatic stellate cells on proliferation of pacnreatic cancer cells

Abstract

Objective To assess the effects of pancreatic stellate cells (PSC) on proliferation of pancreatic cancer cells and to reveal its possible mechanism. Methods Expression and secretion of fibroblast growth factor (FGF) ligands in both pancreatic cancer cells and stellate cells were determined by immunoblotting analysis. Mmethyl thiazol tetrazolium (MTT) assay was used to examine the effects of conditioned medium (CDM) of PSC on the proliferation of pancreatic cancer cells. An in vivo tumorigenicity assay was used to evaluate the effect of PSC on xenograft formation in cancer cells. Results FGF2 was predominantly expressed and secreted by PSC. Yet MIA PaCa-2 and PANC-1 pancreatic cancer cells mainly expressed FGF5. CDM of PSC enhanced the proliferation of MIA PaCa-2 and PANC-1 cells for ( 1. 2993 ±0. 1170 ,P ＜0. 05 ) times and ( 1. 2447 ±0. 0123 ,P ＜0. 05 ) times, respectively. Neutralizing the effects of FGFs in the CDM by heparin-sepharose precipitation abolished this effect. The volume and weight of subcutaneous tumors in nude mice by injection of combination of pancreatic cancer cells with PSC were significantly greater than those by injection of PANC-1 cells alone (380. 13 mm3 and 170 g versus 601.31 mm3and 349 g,P ＜0. 05, respectively). The CDM of PSC reduced the antiproliferative effect by cyclopamine on pancreatic cancer cells ( P ＜ 0. 01, respectively). Conclusion We identified in this study a mechanism based on stroma-tumor interactions involving PSC that can contribute to enhance the proliferation of human pancreatic cancer cells. Key words: Pancreatic stellate cell; Pancreatic cancer; FGF