3-substituted-5-aziridinyl-1-methylindole-4,7-diones as NQO1-directed antitumour agents

mechanism of activation and cytotoxicity in vitro

Mohammed Jaffar, Roger M Phillips, Kaye J Williams, Ibrahim Mrema, Christian Cole, Natasha S Wind, Timothy H Ward, Ian J Stratford, Adam V Patterson

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Indolequinone agents are a unique class of bioreductive cytotoxins that can function as dual substrates for both one- and two-electron reductases. This endows them with the potential to be either hypoxia-selective cytotoxins or NAD(P)H:quinone oxidoreductase 1 (NQO1)-directed prodrugs, respectively. We have studied the structure-activity relationships of four novel indolequinone analogues with regard to one- and/or two-electron activation. Single-electron metabolism was achieved by exposing the human carcinoma cell line T47D to each agent under hypoxic conditions, whilst concerted two-electron metabolism was assessed by stably expressing the cDNA for human NQO1 in a cloned cell line of T47D. The C-3 and C-5 positions of the indolequinone nucleus were modified to manipulate reactivity of the reduction products and the four prodrugs were identified as NQO1 substrates of varying specificity. Two of the four prodrugs, in which both C-3 and C-5 groups remained functional, proved to be NQO1-directed cytotoxins with selectivity ratios of 60- to 80-fold in the T47D (WT) versus the NQO1 overexpressing T47D cells. They also retained selectivity as hypoxic cytotoxins with oxic/hypoxic ratios of 20- to 22-fold. Replacement of the C-3 hydroxymethyl leaving group with an aldehyde group ablated all selectivity in air and hypoxia in both cell lines. Addition of a 2-methyl group on the C-5 aziridinyl group to introduce steric hinderance reduced but did not abolish NQO1-dependent metabolism. However, it enhanced single-electron metabolism-dependent DNA cross-linking in a manner that was independent of cytotoxicity. These data demonstrate that subtle structure-activity relationship exists for different cellular reductases and under certain circumstances distinct forms of DNA damage can arise, the cytotoxic consequences of which can vary. This study identifies a candidate indolequinone analogue for further development as a dual hypoxia and NQO1-directed prodrug.

Original languageEnglish
Pages (from-to)1199-1206
Number of pages8
JournalBiochemical Pharmacology
Volume66
Issue number7
DOIs
Publication statusPublished - 1 Oct 2003
Externally publishedYes

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Indolequinones
Cytotoxicity
Antineoplastic Agents
Chemical activation
Cytotoxins
Prodrugs
Electrons
Metabolism
Oxidoreductases
Cells
Structure-Activity Relationship
Cell Line
DNA
Substrates
Substrate Specificity
Aldehydes
NAD
Functional groups
DNA Damage
1-methylindole

Cite this

Jaffar, Mohammed ; Phillips, Roger M ; Williams, Kaye J ; Mrema, Ibrahim ; Cole, Christian ; Wind, Natasha S ; Ward, Timothy H ; Stratford, Ian J ; Patterson, Adam V. / 3-substituted-5-aziridinyl-1-methylindole-4,7-diones as NQO1-directed antitumour agents : mechanism of activation and cytotoxicity in vitro. In: Biochemical Pharmacology. 2003 ; Vol. 66, No. 7. pp. 1199-1206.
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3-substituted-5-aziridinyl-1-methylindole-4,7-diones as NQO1-directed antitumour agents : mechanism of activation and cytotoxicity in vitro. / Jaffar, Mohammed; Phillips, Roger M; Williams, Kaye J; Mrema, Ibrahim; Cole, Christian; Wind, Natasha S; Ward, Timothy H; Stratford, Ian J; Patterson, Adam V.

In: Biochemical Pharmacology, Vol. 66, No. 7, 01.10.2003, p. 1199-1206.

Research output: Contribution to journalArticle

TY - JOUR

T1 - 3-substituted-5-aziridinyl-1-methylindole-4,7-diones as NQO1-directed antitumour agents

T2 - mechanism of activation and cytotoxicity in vitro

AU - Jaffar, Mohammed

AU - Phillips, Roger M

AU - Williams, Kaye J

AU - Mrema, Ibrahim

AU - Cole, Christian

AU - Wind, Natasha S

AU - Ward, Timothy H

AU - Stratford, Ian J

AU - Patterson, Adam V

PY - 2003/10/1

Y1 - 2003/10/1

N2 - Indolequinone agents are a unique class of bioreductive cytotoxins that can function as dual substrates for both one- and two-electron reductases. This endows them with the potential to be either hypoxia-selective cytotoxins or NAD(P)H:quinone oxidoreductase 1 (NQO1)-directed prodrugs, respectively. We have studied the structure-activity relationships of four novel indolequinone analogues with regard to one- and/or two-electron activation. Single-electron metabolism was achieved by exposing the human carcinoma cell line T47D to each agent under hypoxic conditions, whilst concerted two-electron metabolism was assessed by stably expressing the cDNA for human NQO1 in a cloned cell line of T47D. The C-3 and C-5 positions of the indolequinone nucleus were modified to manipulate reactivity of the reduction products and the four prodrugs were identified as NQO1 substrates of varying specificity. Two of the four prodrugs, in which both C-3 and C-5 groups remained functional, proved to be NQO1-directed cytotoxins with selectivity ratios of 60- to 80-fold in the T47D (WT) versus the NQO1 overexpressing T47D cells. They also retained selectivity as hypoxic cytotoxins with oxic/hypoxic ratios of 20- to 22-fold. Replacement of the C-3 hydroxymethyl leaving group with an aldehyde group ablated all selectivity in air and hypoxia in both cell lines. Addition of a 2-methyl group on the C-5 aziridinyl group to introduce steric hinderance reduced but did not abolish NQO1-dependent metabolism. However, it enhanced single-electron metabolism-dependent DNA cross-linking in a manner that was independent of cytotoxicity. These data demonstrate that subtle structure-activity relationship exists for different cellular reductases and under certain circumstances distinct forms of DNA damage can arise, the cytotoxic consequences of which can vary. This study identifies a candidate indolequinone analogue for further development as a dual hypoxia and NQO1-directed prodrug.

AB - Indolequinone agents are a unique class of bioreductive cytotoxins that can function as dual substrates for both one- and two-electron reductases. This endows them with the potential to be either hypoxia-selective cytotoxins or NAD(P)H:quinone oxidoreductase 1 (NQO1)-directed prodrugs, respectively. We have studied the structure-activity relationships of four novel indolequinone analogues with regard to one- and/or two-electron activation. Single-electron metabolism was achieved by exposing the human carcinoma cell line T47D to each agent under hypoxic conditions, whilst concerted two-electron metabolism was assessed by stably expressing the cDNA for human NQO1 in a cloned cell line of T47D. The C-3 and C-5 positions of the indolequinone nucleus were modified to manipulate reactivity of the reduction products and the four prodrugs were identified as NQO1 substrates of varying specificity. Two of the four prodrugs, in which both C-3 and C-5 groups remained functional, proved to be NQO1-directed cytotoxins with selectivity ratios of 60- to 80-fold in the T47D (WT) versus the NQO1 overexpressing T47D cells. They also retained selectivity as hypoxic cytotoxins with oxic/hypoxic ratios of 20- to 22-fold. Replacement of the C-3 hydroxymethyl leaving group with an aldehyde group ablated all selectivity in air and hypoxia in both cell lines. Addition of a 2-methyl group on the C-5 aziridinyl group to introduce steric hinderance reduced but did not abolish NQO1-dependent metabolism. However, it enhanced single-electron metabolism-dependent DNA cross-linking in a manner that was independent of cytotoxicity. These data demonstrate that subtle structure-activity relationship exists for different cellular reductases and under certain circumstances distinct forms of DNA damage can arise, the cytotoxic consequences of which can vary. This study identifies a candidate indolequinone analogue for further development as a dual hypoxia and NQO1-directed prodrug.

KW - Antineoplastic Agents/chemical synthesis

KW - Aziridines/chemical synthesis

KW - Cell Survival/drug effects

KW - Drug Delivery Systems

KW - Drug Screening Assays, Antitumor

KW - Humans

KW - Indoles/chemical synthesis

KW - Mitomycin/pharmacology

KW - NAD(P)H Dehydrogenase (Quinone)/genetics

KW - Prodrugs/metabolism

KW - Tumor Cells, Cultured

U2 - 10.1016/S0006-2952(03)00452-0

DO - 10.1016/S0006-2952(03)00452-0

M3 - Article

VL - 66

SP - 1199

EP - 1206

JO - Biochemical Pharmacology

JF - Biochemical Pharmacology

SN - 0006-2952

IS - 7

ER -