DNA protein cross-links produced by NSC 652287, a novel thiophene derivative active against human renal cancer cells

2, 5-bis(5-Hydroxymethyl-2-thienyl)furan (NSC 652287), is a representative of a series of thiophene derivatives that exhibit potent and selective anti tumor activity against several tumor cell lines in the National Cancer Inst itute Anticancer Drug Screen. NSC 652287 has noticeable activity for the re nal cell lines and produces cures in certain corresponding xenografts. The cellular mechanisms of action of NSC 652287 were therefore investigated in this study in greater detail. The most sensitive renal carcinoma cell line, A498, exhibited cell cycle arrest in G(0)-G(1) and G(2)-M at 10 nM NSC 652 287, with increased p53 and p21(WAF1) protein. At higher concentrations, NS C 652287 still induced p53 elevation but with p21(WAF1) reduction and massi ve apoptosis. These results collectively suggested that NSC 652287 induced DNA damage. Using alkaline elution techniques, we found that NSC 652287 ind uced both DNA-protein and DNA-DNA cross-links with no detectable DNA single -strand breaks. These DNA-protein cross-links (DPC) persisted for at least 12 h after drug removal and their frequency was correlated with cytotoxicit y in the renal cell lines studied. The most sensitive cells (A498) produced the highest DPC followed by the cell line with intermediate sensitivity (T K-10). DPC were minimal in the two resistant cell lines, ACHN and UO-31. No netheless, a similar degree of DPC occurred at doses imparting equitoxic ef fects. These results indicate that DNA is a primary target for the novel an d potent anticancer thiophene derivative, NSC 652287. NSC 652287 did not cr oss-link purified DNA or mammalian topoisomerase I suggesting the importanc e of active metabolite(s) for the cross-linking activity.