Novel inhibitors of RNA synthesis

Many cancer chemotherapeutic agents inhibit nucleic acid synthesis but their mechanisms of action differ widely. Five drugs that inhibit synthesis of RNA are examined in this paper. Anthramycin, camptothecin and bleomycin act at the level of the DNA template. Anthramycin and camptothecin were studied in HeLa cells and bleomycin in vaccinia virus infected HeLa cells. Anthramycin forms a strong complex with DNA while camptothecin and bleomycin interfere with template function by virtue of their ability to degrade DNA. Gallin, a triphenylmethane dye that is active only in vitro, inhibits RNA synthesis by binding to Escherichia coli RNA polymerase. Steganangin is an example of an inhibitor of RNA synthesis in HeLa cells that acts at the substrate level.