Extracellular matrix composition significantly influences pancreatic stellate cell gene expression pattern: role of transgelin in PSC function

Abstract

Activated pancreatic stellate cells (PSCs) are responsible for the fibrotic matrix of chronic pancreatitis and pancreatic cancer. In vitro protocols examining PSC biology have usually involved PSCs cultured on plastic, a nonphysiological surface. However, PSCs cultured on physiological matrices, e.g., Matrigel (normal basement membrane) and collagen (fibrotic pancreas), may have distinctly different behaviors compared with cells cultured on plastic. Therefore, we aimed to 1) compare PSC gene expression after culture on plastic, Matrigel, and collagen I; 2) validate the gene array data for transgelin, the most highly dysregulated gene in PSCs grown on activating vs. nonactivating matrices, at mRNA and protein levels; 3) examine the role of transgelin in PSC function; and 4) assess transgelin expression in human chronic pancreatitis sections. Culture of PSCs on different matrices significantly affected their gene expression pattern. 146, 619, and 432 genes, respectively, were differentially expressed ( P < 0.001) in PSCs cultured on collagen I vs. Matrigel, Matrigel vs. plastic, and collagen I vs. plastic. The highest fold change (12.5-fold upregulation) in gene expression in cells on collagen I vs. Matrigel was observed for transgelin (an actin stress fiber-associated protein). Transgelin was significantly increased in activated PSCs vs. quiescent PSCs. Silencing transgelin expression decreased PSC proliferation and also reduced platelet-derived growth factor-induced PSC migration. Notably, transgelin was highly expressed in chronic pancreatitis in stromal areas and periacinar spaces but was absent in acinar cells. These findings suggest that transgelin is a potentially useful target protein to modulate PSC function so as to ameliorate pancreatic fibrosis.