Inhibition of 'in vitro' tumor cell growth by aromatic polyamidines exhibiting antiproteinase activity

Aromatic polyamidines containing two, three or four benzamidine residues inhibit proteinase activity and proliferation of different human tumor cell lines, including leukemic (K562, HEL), melanoma (Colo 38) and B-lymphoid (WI-L2) cell lines. In addition, the benzamidine derivatives analysed in the present study inhibit cell growth of the Chinese hamster FHO6T1-1 cell line, obtained after transfection of primary lung cells with the activated human T24-Ha-ras-1 oncogene. After treatment of FHO6T1-1 cells with benzamidine derivatives, a sharp decrease of the content of Ha-ras-1 mRNA was found, but not of transferrin receptor mRNA. We found that inhibition of cell proliferation by tetra-benzamidine derivatives is not restricted to tumor cells, but concerns also non-tumorigenic cell lines as well as normal primary fibroblasts. Therefore, our analysis was extended to di- and tri-benzamidine derivatives, which could be proposed as useful substrates in the synthesis of drug-conjugated monoclonal antibodies or growth factors. The data obtained demonstrate that these latter compounds and their halo-derivatives also exhibit strong antiproliferative effects on in vitro cultured cells.