Development and characterization of a cyclophosphamide-resistant subline of acute myeloid leukemia in the Lewis x Brown Norway hybrid rat

Todd M. Koelling, Andrew M Yeager, John Hilton, Darlene T. Haynie, Joseph M. Wiley

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18 Citations (Scopus)

Abstract

Preclinical studies of resistance to alkylating agents in the Lewis x Brown Norway hybrid (LBN) rat model of acute myeloid leukemia (AML) have hitherto been limited by the sensitivity of LBN AML cells to cyclophosphamide (CY). We developed a CY-resistant subline of LBN AML by serial intravenous (IV) passage of AML cells followed by in vivo exposure to CY (100 mg/kg) 14 days later. After 18 and subsequent passages. CY-treated AML cells remained viable despite ex vivo incubation with 70 to 100 μmol/L 4-hydroperoxycyclophosphamide (4HC) or in vivo exposure to 100 to 300 mg/kg of CY. Once established, resistance to incubation with 4HC was stable in LBN AML cells after at least six serial in vivo passages without exposure to CY. Nevertheless, both control and CY-treated AML cells demonstrated similar dose-dependent sensitivity to 100 to 500 μmol/L phosphoramide mustard (PhM), the active alkylating end-product of CY activation in vivo. Levels of aldehyde dehydrogenase (ALDH), which inactivates CY by prevention of formation of PhM, were significantly elevated in these CY-resistant AML cells: cytosolic and particulate ALDH fractions from these cells were 11 to 13 times control with NAD cofactor and propanal substrate and three to four times control with NADP cofactor and benzaldehyde substrate. Further studies with this animal model of AML, in which resistance to CY is mediated by elevated ALDH activity, may elucidate mechanisms for effective elimination of drug-resistant leukemic cells ex vivo and in vivo.

Original languageEnglish (US)
Pages (from-to)1209-1213
Number of pages5
JournalBlood
Volume76
Issue number6
StatePublished - Sep 15 1990
Externally publishedYes

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Acute Myeloid Leukemia
Cyclophosphamide
Rats
Myeloid Cells
perfosfamide
Aldehyde Dehydrogenase
Serial Passage
Alkylating Agents
Substrates
Norway
NADP
NAD
Animals
Animal Models
Chemical activation

ASJC Scopus subject areas

  • Hematology

Cite this

Development and characterization of a cyclophosphamide-resistant subline of acute myeloid leukemia in the Lewis x Brown Norway hybrid rat. / Koelling, Todd M.; Yeager, Andrew M; Hilton, John; Haynie, Darlene T.; Wiley, Joseph M.

In: Blood, Vol. 76, No. 6, 15.09.1990, p. 1209-1213.

Research output: Contribution to journalArticle

Koelling, Todd M. ; Yeager, Andrew M ; Hilton, John ; Haynie, Darlene T. ; Wiley, Joseph M. / Development and characterization of a cyclophosphamide-resistant subline of acute myeloid leukemia in the Lewis x Brown Norway hybrid rat. In: Blood. 1990 ; Vol. 76, No. 6. pp. 1209-1213.
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abstract = "Preclinical studies of resistance to alkylating agents in the Lewis x Brown Norway hybrid (LBN) rat model of acute myeloid leukemia (AML) have hitherto been limited by the sensitivity of LBN AML cells to cyclophosphamide (CY). We developed a CY-resistant subline of LBN AML by serial intravenous (IV) passage of AML cells followed by in vivo exposure to CY (100 mg/kg) 14 days later. After 18 and subsequent passages. CY-treated AML cells remained viable despite ex vivo incubation with 70 to 100 μmol/L 4-hydroperoxycyclophosphamide (4HC) or in vivo exposure to 100 to 300 mg/kg of CY. Once established, resistance to incubation with 4HC was stable in LBN AML cells after at least six serial in vivo passages without exposure to CY. Nevertheless, both control and CY-treated AML cells demonstrated similar dose-dependent sensitivity to 100 to 500 μmol/L phosphoramide mustard (PhM), the active alkylating end-product of CY activation in vivo. Levels of aldehyde dehydrogenase (ALDH), which inactivates CY by prevention of formation of PhM, were significantly elevated in these CY-resistant AML cells: cytosolic and particulate ALDH fractions from these cells were 11 to 13 times control with NAD cofactor and propanal substrate and three to four times control with NADP cofactor and benzaldehyde substrate. Further studies with this animal model of AML, in which resistance to CY is mediated by elevated ALDH activity, may elucidate mechanisms for effective elimination of drug-resistant leukemic cells ex vivo and in vivo.",
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