Isolation and characterization of a cell line resistant to 5-[3-(2-nitro-1-imidazoyl)-propyl]-phenanthridinium bromide (2-NLP-3), a DNA-intercalating hypoxic cell radiosensitizer and cytotoxin.

Abstract

A DNA-targeted hypoxic cell radiosensitizer and cytotoxin, 5-[3-(2-nitro-1-imidazoyl)-propyl]-phenanthridinium bromide (2-NLP-3), has been shown previously to have increased efficacy over untargeted analogues in vitro. To further study the mechanism of action of this compound, a cell line, CHO-1000, derived from Chinese hamster ovary (CHO) AA8-4 cells was isolated. This cell line is capable of continuously growing in a concentration of 2-NLP-3 approximately 10-fold greater than that tolerated by wild-type CHO cells. The resistance of CHO-1000 to 2-NLP-3 was compared with that of the P-glycoprotein overexpressing, multidrug resistant Chinese hamster cell line CHR-C5 (C5). The resistance of CHO-1000 cells to the acute toxic effects of 2-NLP-3 under both hypoxic and aerobic exposure conditions was intermediate to that of the sensitive CHO wild-type cells and the resistant C5 cells. A similar pattern was seen for the hypoxic cell radiosensitizing ability of 2-NLP-3. 2-NLP-3 produced significant depletion of glutathione under both hypoxic and aerobic conditions in all three cell lines studied, and the degree of depletion was correlated with drug toxicity. CHO-1000 and C5 cells were significantly more resistant to colchicine and doxorubicin compared with wild-type cells. The toxicity pattern of 2-NLP-3 and its comparison phenanthridinium ion, P3, was not the same for CHO-1000 cells compared with C5 cells. Verapamil was an effective agent for reversing the hypoxic resistance to 2-NLP-3 in both CHO-1000 and C5 cells, but only a partial reversal of aerobic resistance was observed in CHO-1000 cells. These results indicate that the resistant phenotype of CHO-1000 is mediated to some degree by P-glycoprotein expression, but that other as yet unidentified factors are also involved.

• Authors: D S Cowan, R A McClelland, A M Rauth
• Journal: Biochemical pharmacology (Biochem Pharmacol) Vol. 50 Issue 1 Pg. 61-8 (Jun 29 1995) ISSN: 0006-2952 [Print] England
• PMID: 7605346 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ATP Binding Cassette Transporter, Subfamily B, Member 1
• Antineoplastic Agents
• Intercalating Agents
• Nitroimidazoles
• Phenanthridines
• Radiation-Sensitizing Agents
• NLP 1
• Glutathione

Topics

• ATP Binding Cassette Transporter, Subfamily B, Member 1 (physiology)
• Animals
• Antineoplastic Agents (pharmacology)
• CHO Cells (drug effects)
• Cell Hypoxia
• Cell Separation
• Cell Survival (drug effects, radiation effects)
• Cricetinae
• Drug Resistance
• Glutathione (metabolism)
• Intercalating Agents (pharmacology)
• Nitroimidazoles
• Phenanthridines (pharmacology)
• Radiation-Sensitizing Agents (pharmacology)