W. Nieves-neira et al., DNA protein cross-links produced by NSC 652287, a novel thiophene derivative active against human renal cancer cells, MOLEC PHARM, 56(3), 1999, pp. 478-484
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.