2, 5-bis(5-Hydroxymethyl-2-thienyl)furan (
NSC 652287), is a representative of a series of
thiophene derivatives that exhibit potent and selective antitumor activity against several tumor cell lines in the National Cancer Institute Anticancer
Drug Screen.
NSC 652287 has noticeable activity for the renal 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 652287, with increased p53 and p21(WAF1)
protein. At higher concentrations,
NSC 652287 still induced p53 elevation but with p21(WAF1) reduction and massive apoptosis. These results collectively suggested that
NSC 652287 induced DNA damage. Using alkaline elution techniques, we found that
NSC 652287 induced 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 cytotoxicity in the renal cell lines studied. The most sensitive cells (A498) produced the highest DPC followed by the cell line with intermediate sensitivity (TK-10). DPC were minimal in the two resistant cell lines, ACHN and UO-31. Nonetheless, a similar degree of DPC occurred at doses imparting equitoxic effects. These results indicate that
DNA is a primary target for the novel and potent anticancer
thiophene derivative,
NSC 652287.
NSC 652287 did not cross-link purified
DNA or mammalian
topoisomerase I suggesting the importance of active metabolite(s) for the cross-linking activity.