Suppression of peritoneal dissemination through protecting mesothelial cells from retraction by cancer cells

In a previous study, we demonstrated that calponin h1 suppressed tumor growth of transformed cells and that the peritonitis carcinomatosa induced by mouse B16-F10 melanoma (F10) cells was more extensive in calponin h1-deficient (CN(-/-)) mice with fragility of mesothelial (MS) cells than in their calponin h1-wild (CN(+/+)) counterparts. In our study, we assessed the therapeutic effect of calponin h1 on peritoneal dissemination. F10 cells were overlaid on the cultured CN(+/+) or CN(-/-) MS cells and the effect of calponin h1 on retraction of MS cells was evaluated. Then, an adenoviral vector with the calponin h1 gene (AdGFP-CN) inserted was constructed and was applied to CN(-/-) MS cells or CN(-/-) mouse peritoneum to investigate its suppressive effect on the peritoneal dissemination caused by F10 cells. Greater retraction and invasion of F10 cells were observed in CN(-/-) MS than in CN(+/+) cells in vitro, while down-regulation of calponin h1 was observed in CN(+/+) MS cells prior to the invasion of F10 cells. Infecting CN(-/-) MS cells with AdGFP-CN prevented their retraction and the invasion of F10 cells. Peritoneal dissemination was prominently suppressed in AdGFP-CN-infected CN(-/-) mice, and the survival of those mice was significantly prolonged. Thus, calponin h1 functioned to protect host MS cells from the invasion of F10 cells.