Monocyte chemoattractant protein-1 gene modification of multidrug-resistant human lung cancer enhances antimetastatic effect of therapy with anti-P-glycoprotein antibody in SCID mice

Distant metastases and multidrug resistance are critical problems in the therapy of human small cell lung cancer (SCLC). In this study, we investigated whether transduction of the monocyte chemoattractant protein-1 (MCP-1) gene into multidrug-resistant (MDR) human lung cancer cells affected the formation of metastases or their inhibition by the anti-P-glycoprotein (P-gp) monoclonal antibody (MAb) MRK16. MDR human SCLC (H69/VP) cells were transduced with the human MCP-1 gene inserted into the expression vector BCMGSNeo. MCP-1 gene transduction had no effect on drug sensitivity, the expression of surface antigens or the in vitro proliferation of H69/VP cells. Using the metastatic model of NK cell-depleted SCID mice, H69/VP cells transduced with the MCP-1 gene were inoculated intravenously (i.v.) and formed metastatic colonies in the liver, kidneys and lymph nodes, similar to those formed by parent or mock-transduced cells. However, systemic treatment of the mice with MRK16 reduced the metastases of H69/VP cells in the liver, kidneys and lymph nodes, and was significantly more effective in inhibiting the metastases of MCP-1 producing H69/VP than those of mock-transduced cells. MCP-1 gene transduction significantly prolonged the survival of tumor-bearing mice treated with MRK16. Our findings suggest that local production of MCP-1 in the tumor site increases the anti-P-gp antibody-dependent cell-mediated cytotoxicity, and the MCP-1 gene-induced modification of MDR human SCLC cells thereby enhances the antimetastatic effect of therapy with anti-P-gp antibody. Thus, the accumulation of effector cells in the tumor site is a very important factor in the therapy using the anti-P-gp antibody.