Tentori L, Portarena I, Vernole P, Gold B, Graziani G. Apoptotic and genotoxic effects of a methyl sulfonate ester that selectively generates N3-methyladenine and poly(ADP-ribose) polymerase inhibitors in normal peripheral blood lymphocytes.
Cancer Chemother Pharmacol 2002;
49:217-24. [PMID:
11935214 DOI:
10.1007/s00280-001-0409-z]
[Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2001] [Accepted: 11/14/2001] [Indexed: 10/27/2022]
Abstract
UNLABELLED
Selective N3-adenine methylation represents a novel strategy for tumors with a phenotype of poor responsiveness to a number of anticancer agents currently used in the clinic. Resistance to N3-methyladenine-inducing agents, such as MeOSO(2)(CH(2))(2)-lexitropsin (Me-Lex), is due to high levels of N-methylpurine glycosylase (MPG). However, tumor cells with high MPG activity can be rendered susceptible to Me-Lex using poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors.
PURPOSE
To evaluate the potential toxicity of Me-Lex, used as single agent or combined with PARP-1 inhibitors, in normal peripheral blood lymphocytes (PBL).
METHODS
PBL either resting or activated with phytohemagglutinin (PHA), obtained from healthy donors, were treated with graded concentrations of Me-Lex with or without PARP-1 inhibitor (3-aminobenzamide, AB, or NU1025, NU). MPG activity, apoptosis and sister chromatid exchanges (SCE) were evaluated.
RESULTS
(a) Me-Lex was cytotoxic mainly in PHA-activated PBL with low MPG activity; (b) combined treatment with Me-Lex and AB induced apoptotic effects as early as 24 h after drug exposure both in non-stimulated and PHA-activated PBL. When concentrations of PARP-1 inhibitors (25 microM NU and 4 m M AB) that produced a twofold increase in Me-Lex cytotoxicity in tumor cells were compared, NU induced a less-pronounced increase in apoptosis in PBL treated with Me-Lex; (c) Me-Lex at concentrations that allowed cytogenetic analysis did not induce a significant number of SCE; (d) PARP-1 inhibitors provoked a dose-dependent increase in SCE, but 25 microM NU was devoid of genotoxic effects and did not significantly increase SCE in PBL treated with Me-Lex.
CONCLUSIONS
Me-Lex showed preferential cytotoxicity against mitogen-activated PBL. Our results also indicated that for each PARP-1 inhibitor it is necessary to define the concentration devoid of genotoxic effects in normal cells, but still capable of enhancing the efficacy of DNA-damaging agents in tumor cells.
Collapse