Interferon-alpha overrides the deficient adhesion of chronic myeloid leukemia primitive progenitor cells to bone marrow stromal cells

Abstract

Primitive blast colony-forming cells (BI-CFC) from chronic myeloid leukemia (CML) patients are defective in their attachment to bone marrow-derived stromal cells compared with normal BI-CFC. We investigated the effect of recombinant interferon-alpha 2a (IFN-alpha) on this interaction between hematopoietic progenitor cells and bone marrow-derived stromal cells by culturing normal stromal cells with IFN- alpha (50 to 5,000 U/mL). At 50 U/mL we found that: (1) the capacity of stromal cells to bind two types of CML primitive progenitor cells (BI- CFC and long-term culture-initiating cells) was increased; and (2) the amount of sulfated glycosaminoglycans (GAGs) in the stromal layer was increased. However, sulfated GAGs were not directly involved in binding CML BI-CFC, unlike binding by normal BI-CFC, which is sulfated GAG- dependent. Neuraminidase-treated control stromal cells bound an increased number of CML BI-CFC, reproducing the effect of IFN-alpha, whereas the binding to IFN-alpha-treated stromal cells was unaffected by neuraminidase treatment. Thus, the enhanced attachment by primitive CML progenitor cells to INF-alpha-treated stromal cells might be due to changes in the neuraminic acid composition in the stromal cell layer. Our in vitro evidence may provide insights into the mechanism of action of IFN-alpha in vivo. Prolonged administration may alter the marrow microenvironment in some patients such that it can restrain the aberrant proliferation of Philadelphia chromosome (Ph)-positive stem cells while permitting Ph-negative stem cells to function normally.

Biological and chemical selection of ph‐negative clones

“…Similar data have been reported by Verjiaillie et al [27]. Recently, Dowding et al [28] and Osterholz et al [29] showed that interferon-alpha enhances the capacity of marrow stromal cells to bind CML progenitor cells without, indeed, selecting for Ph-negative clonogenic cells. The apparent discrepancy between our report and those of others [28, 291 could be explained either by the presence of interferon-alpha during the adherence procedure with the consequent attachment of a predominantly leukemic clonogenic cell population, or by the use of peripheral blood cells, or by technical differences in the procedure used to harvest stroma non-adherent cells.…”

Tyrosine kinase inhibitors and interferon‐α increase tunneling nanotube (TNT) formation and cell adhesion in chronic myeloid leukemia (CML) cell lines

“…Since IFNα as well as nilotinib were able to increase TNT formation in Kcl-22 cells and IFNα previously have been shown to restore the ability of CML cells ability to bind to fibronectin through restoration of β1 integrin function, we examined β1 integrin as a common feature between the two therapies. 46 Indeed, we found that the change in morphology caused by nilotinib, measured by cellular size, were significantly lower when pre-incubated with a β1 integrin blocking antibody. Also, the induced cell adhesion by both IFNα and nilotinib seemed to involve β1 integrin by significantly increasing the average distance of cell movement when cells were pre-treated with the β1 integrin blocking antibody ( Figure 5C,D).…”

“…Cell adherence to fibronectin has previously been found to correlate with TNT formation 30 and treatment of CML cells with IFNα and TKIs have been shown to increase cell adherence to fibronectin, described through a restoration of the β1 integrin by IFNα. 46,48,64,65 To study the role of β1 integrin in cell adherence and TNT formation, we pre-incubated Kcl-22 cells for 30 min with a β1 integrin blocking antibody before treatment for one hour with either IFNα (100 U/mL ) or nilotinib (1 µM). The Kcl-22 cells, without pre-incubation with the β1 integrin blocking antibody (Ctr), showed transformed cell morphology and significantly increased cell surface area on the fibronectin coated surface following nilotinib treatment, whereas IFNα treatment resulted in altered morphology only without significant changes in cell surface area ( Figure 5A,B).…”

“…45 IFNα treatment has been demonstrated to increase adhesion of CML progenitor cells to bone marrow stromal cells. [46][47][48] Restoration of the adhesion defect in CML cells seems therefore to be a significant feature of the effective CML therapy, recently revisited in the therapeutic combination of TKIs and IFNα eradicating CML progenitor cells resulting in non-detectable disease. 5,49 Here, we investigate the role of TKIs and IFNα treatment on TNT formation in CML cell models connecting TNT formation to increased cell attachment to fibronectin coated surfaces.…”

Adenovirus Mediated Alpha Interferon (IFN‐α) Gene Transfer into CD34+Cells and CML Mononuclear Cells

“…Numerous clinical trails have documented the ability of IFN to induce hematologic and cytogenetic remissions in patients with CML [22]. A number of in vitro effects of IFN-α on CML cells and stroma have been well documented, including inhibition of CML marrow progenitor growth [23,24], restoration of the adherence to stroma [25][26][27], and regulation of stromal cytokine production [28] and cellular immune surveillance [29][30][31][32][33] important in the control of growth of the leukemic clone in CML.…”