Intracellular metabolism of Ara-C and resulting DNA fragmentation and apoptosis of human AML HL-60 cells possessing disparate levels of Bcl-2 protein

G. Bullock, S. Ray, J. C. Reed, S. Krajewski, A. M. Ibrado, Y. Huang, K. Bhalla

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

We examined the effects of high intracellular levels of Bcl-2 on the metabolism and DNA incorporation of high dose Ara-C (HIDAC) as well as on Ara-C-induced DNA strand breaks and apoptosis of human AML HL-60 cells. HL-60/Bcl-2 and HL-60/neo cells were created by retrovirally transfecting the human AML HL-60 cells with the pZip-bcl-2 and pZip-neo plasmids, respectively. As compared to HL-60/neo, HL-60/Bcl-2 cells contained significantly higher (approximately 10-fold) p26Bcl-2, but equivalent levels of Bar and undetectable levels of Bcl-x(L). HIDAC (10 or 100μM for 4 h) produced the kilobase size and internucleosomal DNA fragmentation associated with apoptosis in HL-60/neo but not in HL-60/Bcl-2 cells. Significantly greater loss of survival (by MTT assay) and flowcytometric and morphologically recognizable apoptosis were observed in HL-60/neo cells. HIDAC did not affect Bcl-2 levels in either cell type. The intracellular accumulation of Ara-CTP relative to dCTP, Ara-C DNA incorporation and Ara-C-induced early DNA damage in the form of strand breaks (detected by alkaline elution assay) were not significantly different between HL-60/Bcl-2 and HL-60/neo cells. In addition, HIDAC treatment caused similar DNA synthesis inhibition in the two cell types. These results indicate that high intracellular levels of Bcl-2 operate distally to inhibit the final apototic cell death pathway by preventing the conversion of HIDAC-induced early DNA damage into lethal DNA fragmentation associated with apoptosis.

Original languageEnglish (US)
Pages (from-to)1731-1740
Number of pages10
JournalLeukemia
Volume10
Issue number11
StatePublished - Nov 1996
Externally publishedYes

Keywords

  • Ara-CTP
  • Bax
  • Bcl-2
  • Bcl-x(L)

ASJC Scopus subject areas

  • Hematology
  • Cancer Research

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