Recombinant human granulocyte colony-stimulating factor enhanced cytotoxicity of Ara-C in Ara-C-resistant leukemic cells from a patient with biphenotypic leukemia in cell kinetic quiescence

Effect of granulocyte colony-stimulating factor on chemotherapeutic activity of cytosine arabinoside in acute leukemic cell lines

Recent studies have shown the presence of receptors for granulocyte colony-stimulating factor (G-CSF) on lymphoid leukemic cells. To determine the effect of G-CSF on chemotherapeutic activity of cytosine arabinoside (Ara-C) on lymphoid as well as myeloid leukemic cells, we evaluated cell counts, apoptosis, and growth inhibition in HL-60, KG-1, Molt-4, Jijoye, and CCRF-CEM cell lines after incubation with Ara-C (0.1 and 1 micromol/L) and/or 5 ng/mL G-CSE G-CSF potentiated the effect of Ara-C on 2 of 3 lymphoid leukemic cell lines (Molt-4 and Jijoye), whereas it decreased the apoptosis and the effect of Ara-C on myeloid cell lines (HL-60 and KG-1).

Differential effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on the radiation sensitivity of normal versus leukemic bone marrow progenitor cell populations

We examined the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF), interleukin 3 (rhIL-3) and interleukin 6 (rhIL-6) on the radiation sensitivity of normal and leukemic bone marrow progenitor cell populations. Conditioning of leukemic progenitor cells (LPC) from acute lymphoblastic leukemia (ALL) patients with rhG-CSF enhanced their radiation sensitivity, whereas conditioning with rhIL-3 or rhIL-6 had the opposite effect. In contrast to its effects on LPC derived from ALL patients, rhG-CSF reduced the radiation sensitivity of normal myeloid progenitor cells as well as LPC from acute myeloblastic leukemia (AML) patients. Differential modulation of the radiation sensitivity of LPC by rhG-CSF may provide the basis for better total body irradiation (TBI) regimens for ALL patients undergoing autologous bone marrow transplantation (BMT).

Heterogeneous effects of G-CSF and GM-CSF on cell growth and ara-C cytotoxicity in childhood leukemias which express myeloid markers

It is uncertain if acute lymphoblastic leukemia (ALL) cells expressing myeloid makers can respond to granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF). We investigated the effects of G-CSF (0.01 microgram/ml) and GM-CSF (0.01 microgram/ml) on [3H]thymidine (TdR) uptake, and the cytotoxicity of 1-beta-D-arabinofuranosylcytosine (ara-C) in leukemia cells from 17 pediatric patients. ALL cells without myeloid markers did not respond to G-CSF or GM-CSF. On the other hand, these cytokines enhanced the [3H]TdR uptake and cell growth, not only of AML cells but also of ALL cells expressing myeloid antigens. However, G-CSF and GM-CSF did not always enhance the growth inhibitory effect of the cell cycle specific drug ara-C when the cells were co-cultured with the drug. There was no relationship between cell growth and the amount of [3H]TdR incorporation or the intracellular ara-CTP level. These results indicate the heterogeneous effects of G-CSF and GM-CSF on cell growth and ara-C sensitivity in childhood leukemia cells.

Cytokines and cytokine receptors in acute lymphoblastic leukemia expressing myeloid markers--role in growth regulation

There is no evidence that cancer cells including leukemic cells are immortal. It has been clearly indicated that certain cytokines can significantly stimulate leukemic cell proliferation in vitro, and sustain the circuit of autocrine or paracrine stimulation. The biological roles of cytokines and cytokine receptors have been intensively investigated in acute leukemia. Recently coexpression of both lymphoid and myeloid features on a single leukemic cell has been well recognized using a flowcytometric technique. Studies of ALL cells expressing myeloid markers (My+ ALL) have indicated that the profiles of cytokines and cytokine receptors expressed by My+ ALL show both similarities and differences to those in My- ALL or acute myelogenous leukemia (AML), suggesting that My+ ALL cells may originate from uncommitted hematopoietic precursor cells coexpressing features of both lymphoid and myeloid lineages. The exact assessment of cytokine response of leukemic cells would provide an important tool for phenotyping acute leukemia based on the growth properties of the cells (cytokine phenotyping), in addition to the morphologic classification and immunological surface phenotyping. Additionally alteration of sensitivity to cytotoxic anticancer drugs by cytokine stimulation may be the new strategy for biologic therapy of acute leukemia.