Adaptive secretion of granulocyte-macrophage colony-stimulating factor (GM-CSF) mediates imatinib and nilotinib resistance in BCR/ABL+ progenitors via JAK-2/STAT-5 pathway activation

Abstract

IntroductionImatinib mesylate, or IM (Gleevec; Novartis Pharma, Basel, Switzerland), has demonstrated a remarkable efficacy in the treatment of BCR/ABL ϩ leukemias, with most patients in early chronic phase achieving complete cytogenetic remissions (CCRs). 1 Despite this, BCR/ABL ϩ disease remains detectable in essentially all patients with chronic-phase chronic myelogenous leukemia (CML), and CML always recurs after cessation of IM treatment. 2 This reflects disease persistence under IM therapy. Mechanisms of stem and progenitor cell persistence are presumably progenitor cell quiescence, 3,4 BCR/ABL overexpression, 5 BCR/ABL kinase mutations, 6 and influx and efflux pump expression 7,8 regulating intracellular concentrations of IM. However, additional aberrations may be required to cause a fully drug-resistant phenotype. 9 Clinically manifest IM resistance primarily occurs in advanced stages of CML and in BCR/ABL ϩ acute lymphoblastic leukemia (ALL), and is frequently associated with mutations 10-17 in the causative oncogene of CML, BCR/ABL. 18,19 BCR/ABL kinase mutations are today the best-characterized IM resistance mechanism.To overcome mutation-dependent IM resistance, more selective second-generation ABL kinase inhibitors such as nilotinib (NI; AMN107) 20 and dasatinib (DA), 21 a dual-kinase inhibitor of Abl and Src kinases, were developed and recently also introduced into clinical practice. 22,23 However, DA and NI failed to achieve sustained responses in IM-resistant CML blast crisis and ALL. [22][23][24] Interestingly, neither the response nor the depth of response to NI (hematologic or cytogenetic) depended on the presence or absence of kinase mutations in IM-resistant CML and BCR/ABL ϩ ALL 22 . This implies that BCR/ABL-independent resistance mechanisms 25,26 contribute to IM and NI resistance in a major cohort of patients.Using clonal populations of LAMA cells, we have previously shown that a BCR/ABL-independent activation of the PI3K/Akt signaling cascade precedes kinase mutation-dependent IM resistance development in vitro, 27 and that this autonomous pathway activation mediates early BCR/ABL-independent IM resistance. Others have shown a growth factor-dependent, BCR/ABLindependent activation of the Ras-signaling pathway in CD34 ϩ CML progenitors under IM exposure. 28 Here we were seeking to identify putative factors present in the culture supernatant of IM-exposed BCR/ABL ϩ cells that confer IM resistance. Materials and methods Drugs and reagentsIM and NI was kindly supplied by Drs E. Buchdunger and P. Manley (both of Novartis Pharma). NI was dissolved in dimethyl sulfoxide (DMSO) as a For personal use only. on May 11, 2018. by guest www.bloodjournal.org From 10-mM stock solution and stored in aliquots at Ϫ20°C; IM was stored at Ϫ20°C at 10 mM in distilled water. AG490 29 was obtained from CalbiochemNovabiochem (Bad Soden, Germany). Stock solutions (50 mM) were prepared in DMSO and stored in aliquots at Ϫ20°C. Fresh working solutions were prepared in RPMI-1640 for each experiment. The recombinant ...

BCR-ABL mutants spread resistance to non-mutated cells through a paracrine mechanism

“…Autocrine growth loops with IL3, GM-CSF or G-CSF have been described in BCR-ABL cell lines and in CD34 þ cells from CML. [22][23][24][25] Recently, Wang et al 26 reported increased secretion of GM-CSF, in imatiniband nilotinib-resistant cells from the LAMA cell line, and in CD34 þ progenitors from some imatinib-resistant patients with CML. This cytokine was able to protect cells naive to imatinib or nilotinib by activating JAK2/STAT5 and MEK/ERK.…”

Imatinib mesylate and nilotinib (AMN107) exhibit high-affinity interaction with ABCG2 on primitive hematopoietic stem cells

“…We previously demonstrated that flow cytometric measurement of P-CRKL is highly concordant to Western blot analyses. 39 As shown in Figure 4a, untreated K562 parental cells exhibited high levels of P-CRKL, reflecting a high activity of BCR-ABL. Exposure to 500 nM imatinib or 25 nM nilotinib in the parental cell line resulted in a significant loss of CRKL phosphorylation (upper row).…”

Role of GM-CSF in tolerance induction by mobilized hematopoietic progenitors

“…Interestingly, another regulatory T-cell subset, namely invariant natural killer T (iNKT) cells, expresses CD116 through which GM-CSF regulates their effector differentiation. 6 Finally, the recent report that adaptive secretion of GM-CSF occurs in human progenitors 25 in BCR/ABL ϩ patients opens the possibility that GM-CSF may play a role in human peripheral Treg amplification upon transplantation with mobilized hematopoietic progenitors.…”