Cytotoxic and biochemical implications of combining AZT and AG-311

J. Pressacco, B. Mitrovski, C. Erlichman

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We have reported that noncytotoxic concentrations of 3'-azido-3'-deoxythymidine (AZT) increase the cytotoxicity of ICI D 1694, a folate-based thymidylate synthase (TS) inhibitor, with increasing AZT incorporation into DNA. We postulated that the inhibition of TS by ICI D1694 would decrease 5'deoxythymidine triphosphate (dTTP) pools, which compete with AZT triphosphate (AZT-TP) as a substrate for DNA polymerase. Furthermore, the inhibition of TS would increase the activity of both thymidine kinase (TK) and thymidylate kinase (TdK). Each of these consequences of TS inhibition would favor more incorporation of AZT into DNA. Thus, we reasoned that other TS inhibitors should also result in increased AZT incorporation into DNA and, perhaps, in increased cytotoxicity. N6-[4-(Morpholinosulfonyl) benzyl]-N6-methyl-2,6-diaminobenz[cd]indole glucuronate (AG-331) differs from ICI D1694 in that it is a de novo designed lipophilic TS inhibitor, it does not require a specific carrier for cellular uptake, and it does not undergo intracellular polyglutamation. This potent TS inhibitor causes minimal cytotoxicity in MGHI-U1 human bladder cancer cells. A 24-h exposure to 5 μM AG-331 causes almost complete TS inhibition but only 35% cell kill. The combination of AZT and AG-331 in MGH-U1 cells resulted in an enhanced antitumor effect relative to that of each agent alone; 50 μM AZT, noncytotoxic alone, increased the cell kill of induced by AG-331 from 35% to 50%. Biochemical studies of this combination revealed that simultaneous treatment with 5 μM AG-331 plus 1.8 μM [3H]-AZT produced as much as a 68% ± 7% increase in AZT incorporation into DNA. This observration was associated with an increase in DNA single-strand breaks, measured as comet tail moment, of up to 6.6-fold. These studies support our original premise that TS inhibition favors increased incorporation of AZT into DNA and that the combination causes more cell kill than either drug alone in MGH-U1 cells.

Original languageEnglish (US)
Pages (from-to)387-390
Number of pages4
JournalCancer Chemotherapy and Pharmacology
Volume35
Issue number5
DOIs
StatePublished - 1995

Fingerprint

Thymidylate Synthase
DNA
Cytotoxicity
dTMP kinase
Single-Stranded DNA Breaks
Glucuronic Acid
Thymidine Kinase
Zidovudine
DNA-Directed DNA Polymerase
Folic Acid
Urinary Bladder Neoplasms
Tail
Cells
AG 331

Keywords

  • AZT·AG-331
  • Thymidylate synthesis

ASJC Scopus subject areas

  • Cancer Research
  • Oncology
  • Pharmacology

Cite this

Cytotoxic and biochemical implications of combining AZT and AG-311. / Pressacco, J.; Mitrovski, B.; Erlichman, C.

In: Cancer Chemotherapy and Pharmacology, Vol. 35, No. 5, 1995, p. 387-390.

Research output: Contribution to journalArticle

Pressacco, J. ; Mitrovski, B. ; Erlichman, C. / Cytotoxic and biochemical implications of combining AZT and AG-311. In: Cancer Chemotherapy and Pharmacology. 1995 ; Vol. 35, No. 5. pp. 387-390.
@article{dc01af0af8f948b1a22f4af3e6fb442e,
title = "Cytotoxic and biochemical implications of combining AZT and AG-311",
abstract = "We have reported that noncytotoxic concentrations of 3'-azido-3'-deoxythymidine (AZT) increase the cytotoxicity of ICI D 1694, a folate-based thymidylate synthase (TS) inhibitor, with increasing AZT incorporation into DNA. We postulated that the inhibition of TS by ICI D1694 would decrease 5'deoxythymidine triphosphate (dTTP) pools, which compete with AZT triphosphate (AZT-TP) as a substrate for DNA polymerase. Furthermore, the inhibition of TS would increase the activity of both thymidine kinase (TK) and thymidylate kinase (TdK). Each of these consequences of TS inhibition would favor more incorporation of AZT into DNA. Thus, we reasoned that other TS inhibitors should also result in increased AZT incorporation into DNA and, perhaps, in increased cytotoxicity. N6-[4-(Morpholinosulfonyl) benzyl]-N6-methyl-2,6-diaminobenz[cd]indole glucuronate (AG-331) differs from ICI D1694 in that it is a de novo designed lipophilic TS inhibitor, it does not require a specific carrier for cellular uptake, and it does not undergo intracellular polyglutamation. This potent TS inhibitor causes minimal cytotoxicity in MGHI-U1 human bladder cancer cells. A 24-h exposure to 5 μM AG-331 causes almost complete TS inhibition but only 35{\%} cell kill. The combination of AZT and AG-331 in MGH-U1 cells resulted in an enhanced antitumor effect relative to that of each agent alone; 50 μM AZT, noncytotoxic alone, increased the cell kill of induced by AG-331 from 35{\%} to 50{\%}. Biochemical studies of this combination revealed that simultaneous treatment with 5 μM AG-331 plus 1.8 μM [3H]-AZT produced as much as a 68{\%} ± 7{\%} increase in AZT incorporation into DNA. This observration was associated with an increase in DNA single-strand breaks, measured as comet tail moment, of up to 6.6-fold. These studies support our original premise that TS inhibition favors increased incorporation of AZT into DNA and that the combination causes more cell kill than either drug alone in MGH-U1 cells.",
keywords = "AZT·AG-331, Thymidylate synthesis",
author = "J. Pressacco and B. Mitrovski and C. Erlichman",
year = "1995",
doi = "10.1007/s002800050251",
language = "English (US)",
volume = "35",
pages = "387--390",
journal = "Cancer Chemotherapy and Pharmacology",
issn = "0344-5704",
publisher = "Springer Verlag",
number = "5",

}

TY - JOUR

T1 - Cytotoxic and biochemical implications of combining AZT and AG-311

AU - Pressacco, J.

AU - Mitrovski, B.

AU - Erlichman, C.

PY - 1995

Y1 - 1995

N2 - We have reported that noncytotoxic concentrations of 3'-azido-3'-deoxythymidine (AZT) increase the cytotoxicity of ICI D 1694, a folate-based thymidylate synthase (TS) inhibitor, with increasing AZT incorporation into DNA. We postulated that the inhibition of TS by ICI D1694 would decrease 5'deoxythymidine triphosphate (dTTP) pools, which compete with AZT triphosphate (AZT-TP) as a substrate for DNA polymerase. Furthermore, the inhibition of TS would increase the activity of both thymidine kinase (TK) and thymidylate kinase (TdK). Each of these consequences of TS inhibition would favor more incorporation of AZT into DNA. Thus, we reasoned that other TS inhibitors should also result in increased AZT incorporation into DNA and, perhaps, in increased cytotoxicity. N6-[4-(Morpholinosulfonyl) benzyl]-N6-methyl-2,6-diaminobenz[cd]indole glucuronate (AG-331) differs from ICI D1694 in that it is a de novo designed lipophilic TS inhibitor, it does not require a specific carrier for cellular uptake, and it does not undergo intracellular polyglutamation. This potent TS inhibitor causes minimal cytotoxicity in MGHI-U1 human bladder cancer cells. A 24-h exposure to 5 μM AG-331 causes almost complete TS inhibition but only 35% cell kill. The combination of AZT and AG-331 in MGH-U1 cells resulted in an enhanced antitumor effect relative to that of each agent alone; 50 μM AZT, noncytotoxic alone, increased the cell kill of induced by AG-331 from 35% to 50%. Biochemical studies of this combination revealed that simultaneous treatment with 5 μM AG-331 plus 1.8 μM [3H]-AZT produced as much as a 68% ± 7% increase in AZT incorporation into DNA. This observration was associated with an increase in DNA single-strand breaks, measured as comet tail moment, of up to 6.6-fold. These studies support our original premise that TS inhibition favors increased incorporation of AZT into DNA and that the combination causes more cell kill than either drug alone in MGH-U1 cells.

AB - We have reported that noncytotoxic concentrations of 3'-azido-3'-deoxythymidine (AZT) increase the cytotoxicity of ICI D 1694, a folate-based thymidylate synthase (TS) inhibitor, with increasing AZT incorporation into DNA. We postulated that the inhibition of TS by ICI D1694 would decrease 5'deoxythymidine triphosphate (dTTP) pools, which compete with AZT triphosphate (AZT-TP) as a substrate for DNA polymerase. Furthermore, the inhibition of TS would increase the activity of both thymidine kinase (TK) and thymidylate kinase (TdK). Each of these consequences of TS inhibition would favor more incorporation of AZT into DNA. Thus, we reasoned that other TS inhibitors should also result in increased AZT incorporation into DNA and, perhaps, in increased cytotoxicity. N6-[4-(Morpholinosulfonyl) benzyl]-N6-methyl-2,6-diaminobenz[cd]indole glucuronate (AG-331) differs from ICI D1694 in that it is a de novo designed lipophilic TS inhibitor, it does not require a specific carrier for cellular uptake, and it does not undergo intracellular polyglutamation. This potent TS inhibitor causes minimal cytotoxicity in MGHI-U1 human bladder cancer cells. A 24-h exposure to 5 μM AG-331 causes almost complete TS inhibition but only 35% cell kill. The combination of AZT and AG-331 in MGH-U1 cells resulted in an enhanced antitumor effect relative to that of each agent alone; 50 μM AZT, noncytotoxic alone, increased the cell kill of induced by AG-331 from 35% to 50%. Biochemical studies of this combination revealed that simultaneous treatment with 5 μM AG-331 plus 1.8 μM [3H]-AZT produced as much as a 68% ± 7% increase in AZT incorporation into DNA. This observration was associated with an increase in DNA single-strand breaks, measured as comet tail moment, of up to 6.6-fold. These studies support our original premise that TS inhibition favors increased incorporation of AZT into DNA and that the combination causes more cell kill than either drug alone in MGH-U1 cells.

KW - AZT·AG-331

KW - Thymidylate synthesis

UR - http://www.scopus.com/inward/record.url?scp=0028869680&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028869680&partnerID=8YFLogxK

U2 - 10.1007/s002800050251

DO - 10.1007/s002800050251

M3 - Article

VL - 35

SP - 387

EP - 390

JO - Cancer Chemotherapy and Pharmacology

JF - Cancer Chemotherapy and Pharmacology

SN - 0344-5704

IS - 5

ER -