gilvocarcin-v and chartreusin

Elsamicin (EM) is a recently discovered antitumour agent that is structurally related to several other compounds displaying anticancer activities, including chartreusin (CT), chrysomycin V (CV) and M (CM), gilvocarcin V (GV) and ravidomycin (RM). The biochemical events resulting in cytotoxicity for most of these compounds have not been clearly elucidated. There is some evidence that GV and CT bind to DNA and that GV is photosensitive, causing DNA damage. Therefore, we investigated the effects of these chemicals on DNA in cells and on pBR322 plasmid DNA. Using alkaline elution techniques, we found that all these compounds induced, to a different extent, DNA breakage in the human lung adenocarcinoma A549 cell line. In addition, all either bound to or intercalated into DNA, as indicated by their ability to alter the electrophoretic migration of DNA in agarose gels. Using the P4 unknotting assay, EM, CT, CV, CM, GV and RM were found to be potent inhibitors of the catalytic activity of topoisomerase II (topo II). Their potencies were compared with the known topo II inhibitors teniposide (VM-26) and doxorubicin (DX). EM was the most potent, with an IC50 of 0.4 mumol/l followed in order by CV, GV, and CT. VM-26 was the least potent with an IC50 of 15 mumol/l. It was concluded from these results that EM, GV, CV, CM and CT are capable of inhibiting topo II and that EM is the most potent inhibitor of topo II yet discovered.

Topics: Adenocarcinoma; Aminoglycosides; Anti-Bacterial Agents; Antibiotics, Antineoplastic; Benzopyrans; Cell Division; Coumarins; DNA Damage; DNA, Neoplasm; Glycosides; Humans; Lung Neoplasms; Topoisomerase II Inhibitors; Tumor Cells, Cultured

Gilvocarcins that are antitumor agents are activated by low doses of visible light to induce bacteriophage lambda in Escherichia coli. This result is dependent on interaction with DNA. Gilvocarcin M, an analog without antitumor activity, failed to induce the prophage after light exposure, thus demonstrating a correlation between photosensitizing and antitumor activities. These results raise several possibilities regarding the mode of action of gilvocarcins as antitumor agents in vivo, involving light or enzymatic activating systems, which could be exploited in human cancer therapy.

Topics: Aminoglycosides; Anti-Bacterial Agents; Antibiotics, Antineoplastic; Bacteriophage lambda; Benzopyrans; Coumarins; Glycosides; Light; Methoxsalen; Structure-Activity Relationship; Trioxsalen; Ultraviolet Rays; Virus Activation