Abl protein kinase abrogates the response of multipotent haemopoietic cells to the growth inhibitor macrophage inflammatory protein-1 alpha

Abstract

The clonogenic cells of chronic myeloid leukaemia (CML), unlike normal haemopoietic progenitor cells, are resistant to the growth inhibitory e ects of the chemokine macrophage in¯ammatory protein-1 alpha (MIP-1a). CML is also relatively resistant to chemotherapy and the disease is di cult to cure using conventional therapeutic routes. CML is associated with increased abl oncogene protein tyrosine kinase (PTK) activity. Here, we have tested the hypothesis that these aberrant responses to MIP1a and the relative resistance to chemotherapy are directly related to this increased abl PTK activity in primitive haemopoietic cells. To do this we have expressed a temperature sensitive abl PTK in a growth factor dependent, multipotent stem cell line (FDCP-Mix) in which growth is normally suppressed by MIP-1a. In FDCP-Mix cells expressing the ts v-abl PTK and grown at the restrictive temperature for PTK activity the cells were relatively sensitive to cytotoxic agents such as cytosine arabinoside and 5-¯uorouracil but MIP-1a could induce growth inhibition and confer some degree of protection from these agents. At the permissive temperature for abl PTK, the cells were relatively resistant to cytotoxic drugs and MIP-1a treatment neither induced growth inhibition nor protected the cells from cytotoxic drug induced cell death. This lack of response to MIP-1a was not due to receptor down modulation as neither the a nity nor the number of 125 I-MIP-1a binding sites was altered by activating Abl PTK. However, MIP-1a mediated increases in cytosolic Ca 2+ levels were abrogated by switching cells to the permissive temperature for Abl PTK activity. These data suggest that the relative resistance of CML progenitor cells to therapeutic drugs and the lack of response to MIP1a occurs as a direct consequence of abl PTK activity and involves desensitisation of signal transduction events stimulated by MIP-1a receptors. Thus one contributory mechanism to transformation of primitive haemopoietic cells is abrogation of response to a growth inhibitor.

True

“…These data agree with our recently published findings in the vabl transfected FDCP-Mix cell line, 32 where MIP-1␣-induced sensitisation to Ara-C was strictly dependent on the overexpression of functional v-abl protein tyrosine kinase (PTK). Taken together these results suggest that the cytoprotective and growth inhibiting effects of MIP-1␣ on normal haemopoietic cells may be distinct biological activities of the chemo-…”

“…This finding confirms previous experiments 25 and our own results obtained in a murine v-abl transfected stem cell model. 32 Based on these observations we next tested the hypothesis that MIP-1␣ can selectively protect normal haemopoietic progenitor cells whilst maintaining (or even increasing) the sensitivity of leukaemic cells to cell-cycle active chemotherapeutic drugs. To this end we developed a 24 h Ara-C protection assay.…”

“…The receptor data also agree with our results in the abl PTK FDCP-Mix model, that the expression of abl PTK activity in FDCP-Mix cells does not influence the overall expression of MIP-1␣ receptors. 32 To further investigate potential defects in the coupling of MIP-1␣ receptors in CML cells to intracellular signal transduction cascades, we compared the effects of MIP-1␣ on the adhesion of CML and normal CD34 + cells to the extracellular matrix molecule fibronectin. 42 Recently, we and others have demonstrated that CD34 + cell adhesion to fibronectin coated plastic surfaces is mainly mediated by both ␣4␤1 and ␣5␤1…”

Retroviral transfer and expression of human MDR-1 in a murine haemopoietic stem cell line does not alter factor dependence, growth or differentiation characteristics

“…31 Expression of activated ras leads to a block in differentiation of these cells, 35 whilst v-abl and bcr-abl both lead to changes in the growth factor response of FDCP-mix. 31,36,37 No effect of p-glycoprotein expression on any of these parameters was seen which could explain the previously reported myeloproliferative disease. Growth factor dependence, proliferation (even under the growth factor conditions used by Bunting et al 12 ) and differentiation were all the same as in control cells.…”

Expression of CCL9/MIP-1γ is repressed by BCR/ABL and its restoration suppresses in vivo leukemogenesis of 32D-BCR/ABL cells

“…Together, these data point to mechanisms of transformation by p210 BCR/ABL , which do not depend only on the autonomous properties of transformed cells, but also on the relationship of these cells with the microenvironment. The role of other chemokines and chemokine receptors in CML is under active investigation: CML progenitors fail to respond to CCL3 and CCL2 (Eaves et al, 1993;Wark et al, 1998), and levels and/or activity of chemokine receptors (Salgia et al, 1999;Ptasznik et al, 2002;Geay et al, 2005;Jongen-Lavrencic et al, 2005) are downregulated in p210 BCR/ABL -expressing cells, changes potentially involved in the abnormal trafficking of CML progenitors and in their release from the bone marrow. Our findings indicate that the production of some chemokines may also be impaired in p210 BCR/ABL -expressing cells and suggest that restoration of chemokine expression negatively affects leukemogenesis.…”