A novel transforming growth factor beta receptor kinase inhibitor, A-77, prevents the peritoneal dissemination of scirrhous gastric carcinoma.

Purpose: Transforming growth factor beta receptor (TGFbeta-R) is reported to correlate with the malignant potential of scirrhous gastric carcinoma. The aim of the current study is to clarify the possibility of molecular target therapy with a TGFbeta-R inhibitor, A-77, for the treatment of peritoneal dissemination of scirrhous gastric cancer.

Experimental Design: Three scirrhous gastric cancer cell lines and two fibroblasts were used. For in vivo experiments, the A-77 was administered i.p. to mouse models of peritoneal dissemination. The influences of A-77 on the adhesion ability, invasion ability, and the expression of adhesion molecules were examined in vitro.

Results: The A-77 administration resulted in a significantly (P < 0.01) better prognosis for the mice with peritoneal dissemination (median survival time, 51 days), compared with the control (median survival time, 25 days). A-77 therefore significantly (P < 0.01) decreased the weight and number of metastatic nodes. The adhesive ability and invasion ability of cancer cells were significantly decreased by A-77. A-77 decreased the expression of alpha(2), alpha(3), and alpha(5) integrins in gastric cancer cells. The histologic findings showed the degree of fibrosis to be less in the tumors treated by A-77. A-77 decreased the growth of fibroblast and invasion-stimulating activity of fibroblasts on cancer cells.

Conclusion: The TGFbeta-R inhibitor, A-77, decreased the expression of integrins in cancer cells and the proliferation of fibroblasts, which resulted in the decreased adhesive and invasive abilities of scirrhous gastric cancer cells to peritoneum. A-77 is thus considered to be useful for the inhibition of peritoneal dissemination of scirrhous gastric carcinoma.