title: Granulocyte-macrophage colony-stimulating factor/interleukin-3 fusion protein (pIXY 321) enhances high-dose Ara-C-induced programmed cell death or apoptosis in human myeloid leukemia cells.
abstract: High dose Ara-C (HIDAC) induces programmed cell death (PCD) or apoptosis in vitro in human myeloid leukemia cells, which correlates with the inhibition of their clonogenic survival. Hematopoietic growth factors (HGFs) granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) have been demonstrated to enhance the metabolism and cytotoxic effects of HIDAC against leukemic progenitor cells. We examined the effect of pIXY 321 (a GM-CSF/IL-3 fusion protein) on HIDAC-induced PCD and related gene expressions as well as HIDAC-mediated colony growth inhibition of human myeloid leukemia cells. Unlike the previously described effects of HGFs on normal bone marrow progenitor cells, exposure to pIXY 321 alone for up to 24 hours did not suppress PCD in HL-60 or KG-1 cells. However, exposure to pIXY 321 for 20 hours followed by a combined treatment with Ara-C plus pIXY 321 for 4 or 24 hours versus treatment with Ara-C alone significantly enhanced the oligonucleosomal DNA fragmentation characteristic of PCD. This was temporally associated with a marked induction of c-jun expression and a significant decrease in BCL-2. In addition, the treatment with pIXY 321 plus HIDAC versus HIDAC alone produced a significantly greater inhibition of HL-60 colony growth. These findings highlight an additional mechanism of HIDAC-induced leukemic cell death that is augmented by cotreatment with pIXY 321 and may contribute toward an improved antileukemic activity of HIDAC.
authors.affiliation: Division of Hematology/Oncology, Medical University of South Carolina, Charleston 29425.
authors.forename: K
authors.initials: K
authors.lastname: Bhalla
authors.forename: C
authors.initials: C
authors.lastname: Tang
authors.forename: A M
authors.initials: AM
authors.lastname: Ibrado
authors.forename: S
authors.initials: S
authors.lastname: Grant
authors.forename: E
authors.initials: E
authors.lastname: Tourkina
authors.forename: C
authors.initials: C
authors.lastname: Holladay
authors.forename: M
authors.initials: M
authors.lastname: Hughes
authors.forename: M E
authors.initials: ME
authors.lastname: Mahoney
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
mesh_terms: D000199:Actins / Q000235:genetics; D017209:Apoptosis / Q000187:drug effects*; D015152:Blotting, Northern; D016923:Cell Death / Q000187:drug effects*; D003561:Cytarabine / Q000494:pharmacology*; D004357:Drug Synergism; D019204:GTP-Binding Proteins / Q000235:genetics; D016758:Genes, jun / Q000187:drug effects; D016259:Genes, myc / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology*; D007700:Kinetics; D007951:Leukemia, Myeloid; D015473:Leukemia, Promyelocytic, Acute; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D011519:Proto-Oncogenes / Q000187:drug effects*; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D000199:Actins; D007377:Interleukin-3; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012334:RNA, Neoplasm; D011993:Recombinant Fusion Proteins; D003561:Cytarabine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019204:GTP-Binding Proteins