Differential expression of hepatocyte growth factor and its receptor (c-Met) in a rat artificial anus model

Hepatocyte growth factor is a multifunctional polypeptide that has been imp licated in cancer growth, tissue development and wound repair. It is mainly synthesized in mesenchymal cells and acts on epithelial cells, where its a ctions are dependent on binding to a specific cell-surface hepatocyte growt h factor receptor (c-Met). In an artificial anus, two different types of ep ithelial cells (ductal cells of the colon and squamous cells of the skin) i ntermingle with each other. In the present study, we examined the localizat ion of hepatocyte growth factor and c-Met during the process of repair in a rat artificial anus model, and attempted to clarify the cell types that ex press hepatocyte growth factor or c-Met messenger RNA by in situ hybridizat ion. Western blot analysis revealed abundant localization of the mature for m of hepatocyte growth factor in artificial anal tissues. Moderate hepatocy te growth factor immunoreactivity was noted in regenerated squamous cells i n the skin and colonic ductal cells, and strong expression in macrophages a nd fibroblasts. Moderate c-Met immunoreactivity was present in regenerated epithelial cells in the skin and colon. Throughout the repair process, hepa tocyte growth factor and c-Met immunoreactivities were more prominently loc alized in the squamous cells of the skin than in colonic ductal cells. Comp etitive reverse transcription-polymerase chain reaction analysis revealed t hat hepatocyte growth factor mRNA was maximal on day 14 after the operation : however, c-Met mRNA expression had two peaks, on day 1 and day 7. Hepatoc yte growth factor mRNA was expressed more in the stromal fibroblasts, macro phages and endothelial cells, and c-Met mRNA was predominant in regenerated squamous cells of the skin. These findings suggest the possibility that he patocyte growth factor may act in a paracrine manner to mainly enhance the growth of squamous cells of the skin and to a lesser extent the ductal cell s of the colon in the artificial anus.