CHLORPHENIRAMINE INHIBITS THE SYNTHESIS OF ORNITHINE DECARBOXYLASE AND THE PROLIFERATION OF HUMAN BREAST-CANCER CELL-LINES

Proliferation of both mouse and human breast cancer cells was inhibite d by chlorpheniramine (CPA) in a dose-response manner. At the beginnin g of the exponential phase of growth (two days after seeding), 250 mu M CPA was able to reduce cell proliferation by 75% (in Ehrlich cell cu ltures) and 30% (in MCF-7 cultures). The antiproliferative effect of C PA was also tested on a poorly-differentiated and hormone-insensitive human breast cancer cell line (MDA-MB231) and on a highly proliferativ e human colon cancer cell line (clone 3). CPA was cytotoxic for MDA-MB 231 cells at concentrations higher than 50 mu M, and it was also cytot oxic for the colon cancer cell clone 3 at 250 mu M CPA. Nevertheless, colon cancer cells were slightly stimulated at CPA concentrations less than 100 mu M. CPA reduced (by 50-70%) the ornithine decarboxylase in duction occurring early after culture seeding of experimental mammary tumors (Ehrlich carcinoma cells) and human breast cancer cells (MCF-7) . The presented data suggest that in addition to ODC inhibition, CPA p resents other still unknown cytotoxic effects.