Analysis of the DNA damage produced by a platinum-acridine antitumor agent and its effects in NCI-H460 lung cancer cells

• Published in: Metallomics 2012-01, Vol.4 (7), p.645-652
• Main Authors: Qiao, Xin, Zeitany, Alexandra E, Wright, Marcus W, Essader, Amal S, Levine, Keith E, Kucera, Gregory L, Bierbach, Ulrich
• Format: Article
• Language: English
• Subjects: Acridines - chemistry; Acridines - pharmacology; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Antitumor agents; Cell Line, Tumor; Cell Survival - drug effects; Cell-Free System; Chromatography, High Pressure Liquid; Chromatography, Reverse-Phase; Cisplatin; Cisplatin - chemistry; Cisplatin - pharmacology; DNA adducts; DNA Adducts - chemistry; DNA Adducts - metabolism; DNA Damage; DNA, Neoplasm - metabolism; Drug Screening Assays, Antitumor; Guanine; High-performance liquid chromatography; Humans; Hybrids; Intracellular levels; Lung cancer; Lung Neoplasms - pathology; Mass spectroscopy; Nucleotides; Platinum - chemistry; Platinum - pharmacology; Spectrometry, Mass, Electrospray Ionization; Tumors
• ISSN: 1756-5901; 1756-591X
• DOI: 10.1039/c2mt20031g

High-performance liquid chromatography in conjunction with electrospray mass spectrometry (LC-ESMS) was used to structurally characterize the adducts formed by the platinum-acridine agent [PtCl(en)( N -(2-(acridin-9-ylamino)ethyl)- N -methylpropionimidamide)](NO 3 ) 2 (compound 1 ) in cell-free DNA. Compound 1 forms monofunctional adducts exclusively with guanine, based on the fragments identified in enzymatic digests (dG*, dGMP*, dApG*, and dTpG*, where the asterisk denotes bound drug). The time course of accumulation and DNA adduct formation of compound 1 and the clinical drug cisplatin in NCI-H460 lung cancer cells at physiologically relevant drug concentrations (0.1 M) was studied by inductively-coupled plasma mass spectrometry (ICP-MS). Compound 1 accumulates rapidly in cells and reaches intracellular levels of up to 60-fold higher than those determined for cisplatin. The hybrid agent shows unusually high DNA binding levels: while cisplatin adducts form at a maximum frequency of 5 adducts per 10 6 nucleotides, compound 1 produces 25 adducts per 10 6 nucleotides after only 3 h of continuous incubation with the lung cancer cells. The high overall levels of compound 1 in the cells and in cellular DNA over the entire 12-h treatment period translate into a rapid decrease in cell viability. Possible implications of these findings for the mechanism of action of compound 1 and the agent's potential to overcome tumor resistance to cisplatin are discussed. Compound 1 rapidly accumulates in NCI-H460 cells to cause significantly higher DNA adduct levels and more efficient cell kill than cisplatin.