Abstract
Cisplatin is a widely used anticancer drug and forms inter- and intrastrand DNA crosslink and monoaducts. While, 3-nitrobenzanthrone (NBA) is a carcinogenic air contaminant and forms several kind of bulky DNA adducts (ABA adducts) in vivo and in vitro. These DNA adducts can cause mutations through translesion DNA synthesis (TLS).
A purpose of this research is to analyze the mutations caused by cisplatin and ABA adducts in human cells. We constructed six shuttle vector plasmids containing one of the following adducts: Pt-GG; Pt-GTG; dG-C8-N-ABA; dG-C2-C8-ABA; dG-N2-C2-ABA; and dA-N6-C2-ABA), site-specifically. We introduced these plasmids into human NER deficient XPA cells for replication, and then analyzed frequencies of TLS and the type of mutations of the replicated plasmids.
We found that all adducts blocked DNA synthesis, but a portion of the adducted plasmids was replicated by TLS. The TLS frequencies were different among the adducts. In cicplatin adducts, Pt-GTG caused more mutations than Pt-GG, and the mutations were observed at the downstream sites from the addected bases. On the other hand, dG-C8-N-ABA was the most mutagenic adduct among the ABA adducts.
