Effect of Ionizing Radiation on Homotypic Cell Adhesion, Cell-Matrix Adhesion, Matrix Metalloproteinases Excretion of High Mucin Producing HM7 Colon Cancer Cells

ABSTRACT

PURPOSE: To investigate the effect of ionizing radiation on high mucin-producing colon cancer cells, we evaluated homotypic cell adhesion, cell-matrix adhesion, and matrix metalloproteinases (MMPs) on HM7 cells. METHODS: After an irradiation of 60 Gy for 48 hours on HM7 cells, we evaluated cellular proliferation, colony-forming ability, homotypic adhesion, cell-matrix binding, and integrin subunit expressions. Also, alterations of MMPs expression were analyzed by using zymography. RESULTS: Cell proliferation of HM7 colon cancer cells was not remarkably affected even after high doses of radiation; however, clonogenic cell growth was significantly affected. Homotypic cell-cell adhesion and cell adhesion to ECM components and basement membrane protein matrigel were significantly increased after irradiation. Radiation induced expressions of cell surface integrin alpha2, alpha3, and beta1 subunits of HM7 cells. The activities of secreted MMPs (MMP-9 and MMP-2) were remarkably inhibited by radiation. CONCLUSIONS: These finding suggest the biologic characteristics of high-mucin-producing colorectal carcinomas. Even though the radiation-associated cellular alterations of HM7 cells with or without matrix proteins were not remarkably different from other cancer cell types studied, the radio-resistant behavior of high mucin producing HM7 cells may explain the aggressive characteristics of mucinous colorectal carcinomas.