Biological and Proteomic Characteristics of an Immortalized Human Pancreatic Stellate Cell Line

Human pancreatic stellate cells (PSCs) play a critical role in fibrogenesis during chronic pancreatitis (CP). However, primary PSCs have a short lifespan in vitro, which seriously affects their use in various applications. We have established a stable immortalized human PSC line (HP-1) by RSV promoter/enhancer-driven SV40 T antigen expression in primary activated human PSCs. HP-1 cells express cytoskeleton proteins including glial fibrillary acidic protein (GFAP), alpha-smooth muscle actin (alpha-SMA), vimentin and desmin, and are typical of PSCs, which are high transfeciability and viable in 0.5% serum. The cells express receptors such as TGFbetaR2, PDGFR, TGF-beta pseudoreceptor Bambi and PPRPgamma that are commonly found in PSCs. HP-1 cells are similar to activated human PSCs in that they have enhanced expression of alpha-SMA, CTGF, Col1 and TIMP-2 mRNAs or proteins, as well as decreased expression of MMP-1/2 mRNAs or proteins in response to TGF-beta1 stimulation. Comparative proteomics revealed 4,537 shared proteins between HP-1 cells and PSCs and no single protein in HP-1 cells versus PSCs. Statistical analysis reveals no significantly difference between HP-1 cells and PSCs in their expression of proteins associated with matrix and matrix remodeling. The similarity between HP-1 cell and PSC is further shown by the finding that only 9 proteins are differentially up-regulated > +/- 2-fold in HP-1 cells and 13 proteins are up-regulated > +/- 2-fold in PSCs and none of these proteins include ECM proteins, cytokines, growth factors or matrix remodeling regulatory proteins. Therefore, HP-1 cells can be used as an effective tool for the study of PSC-mediated pancreatic fibrosis.