کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2514831 1118488 2007 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Identification of human reductases that activate the dinitrobenzamide mustard prodrug PR-104A: A role for NADPH:cytochrome P450 oxidoreductase under hypoxia
موضوعات مرتبط
علوم پزشکی و سلامت داروسازی، سم شناسی و علوم دارویی داروشناسی
پیش نمایش صفحه اول مقاله
Identification of human reductases that activate the dinitrobenzamide mustard prodrug PR-104A: A role for NADPH:cytochrome P450 oxidoreductase under hypoxia
چکیده انگلیسی

Hypoxia is a common trait found in many solid tumours and thus represents a therapeutic target with considerable potential. PR-104, a hypoxia-activated prodrug currently in clinical trial, is a water-soluble phosphate ester which is converted in vivo to the corresponding alcohol, PR-104A. This 3,5-dinitrobenzamide-2-nitrogen mustard is activated by reduction to the corresponding 5-hydroxylamine (PR-104H) and 5-amine (PR-104M) in hypoxic cells. The clinical effectiveness of PR-104 will depend in part on the expression of reductases within tumours that can effect this reduction. Here, we evaluate the roles of NADPH:cytochrome P450 oxidoreductase (CYPOR; E.C.1.6.2.4) and NAD(P)H:quinone oxidoreductase (NQO1; E.C.1.6.99.2) as candidate PR-104A reductases. A weak correlation was observed between NQO1 activity and aerobic cytotoxicity in a panel of eight tumour cell lines. However, overexpression of human NQO1 did not increase cytotoxicity of PR-104A or the formation of PR-104H/M, showing that PR-104A is not a substrate for NQO1. Overexpression of human CYPOR did, however, increase the hypoxic cytotoxicity of PR-104A, and its metabolism to PR-104H and PR-104M, demonstrating it to be a PR-104A reductase. To assess the contribution of CYPOR to overall activation of PR-104A in hypoxic SiHa cells, a combination of siRNA transfection and antisense expression were used to suppress CYPOR protein by 91% (±3%), a phenotype which conferred 45% (±7%) decrease in cytotoxic potency of PR-104A. Regression analysis of all CYPOR depletion data was found to correlate with cytoprotection and metabolism (p < 0.001). Residual PR-104A reductase activity could be inhibited by the flavoprotein inhibitor diphenyliodonium. We conclude that CYPOR is an important PR-104A reductase, but that other flavoenzymes also contribute to its activation in hypoxic SiHa cells.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biochemical Pharmacology - Volume 74, Issue 6, 15 September 2007, Pages 810–820
نویسندگان
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