Bifunctional therapeutic effects on peritoneal cell layer and cancer cells in calponin h1 gene therapy to prevent peritoneal dissemination of ovarian cancer

Abstract

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Calponin h1 (CNh1), one of the family of actin-binding proteins, stabilizes the filaments of actin and modulates various cellular biological phenotypes. We have reported that ovarian cancer cells secrete factors and probably make favorable environment for their invasion through the down-regulation of CNh1 and alpha-smooth muscle actin (α-SMA) in host stromal cells, such as peritoneal mesothelial cells, fibroblasts and cells forming blood vessel walls. In this study, we investigated the effects of CNh1 gene-transfection into peritoneal cells and ovarian cancer cells, and the efficacy of intraperitoneal (i.p.) CNh1 gene therapy against peritoneal dissemination of ovarian cancer. Adenoviral vector-mediated CNh1 gene transfections into peritoneal cells and ovarian cancer cells induced the stable formation of longer and thicker actin stress fibers. The infected peritoneal cells acquired an ability to resist intercellular dissociation induced by the conditioned medium of ovarian cancer cells, and thus cancer cell invasion through the monolayer of peritoneal cells was inhibited. In addition, CNh1-transfected ovarian cancer cells showed retarded growth property and invasiveness, the latter of which accompanied impaired cell motility. The concomitant CNh1 transfection into both the peritoneal cells and ovarian cancer cells produced an additive inhibitory effect with respect to cancer cell invasion through the peritoneal cell monolayer. In in vivo experiments designed to treat nude mice i.p. inoculated with ovarian cancer cells, we found that the i.p. injected CNh1-adenovirus successfully blocked ovarian cancer-induced morphological changes in peritoneal cell surface, and significantly prolonged the survival time of tumor-bearing mice without any serious side effects. Thus CNh1 gene therapy against peritoneal dissemination of ovarian cancer is bifunctionally effective, i.e. through inhibitory effects on the infected peritoneal cell layers which suppress cancer invasion and, second, through direct anti-tumor effect on invasion and growth properties of cancer cells. As such, this therapy may be considered as a potentially novel therapeutic intervention, whereby one and the same gene has two distinctive effects: one to control the cancer cells and the other to bolster a host defense (anti-invasive) mechanism.