Differential Bone Marrow Homing Capacity of VLA-4 and CD38 High Expressing Chronic Lymphocytic Leukemia Cells

Abstract

BackgroundVLA-4 and CD38 predict a poor clinical outcome in chronic lymphocytic leukemia (CLL). We used CLL samples with discordant VLA-4/CD38 risk to address their individual roles in human bone marrow infiltration (BM), CLL cell homing to murine BM, and in supportive CLL cell-stromal cell interactions.MethodsVLA-4, CD38, and Ki-67 expression was measured in CLL cells from peripheral blood (PB) and bone marrow (BM) aspirates. CLL BM infiltration rates, routinely determined by Pathology, were correlated to VLA-4 and CD38 expression. Short-term homing capacity of CLL cells was evaluated by adoptive transfer experiments. CLL cell viability and adhesion in stromal cell co-culture was determined.ResultsAbout 20% of CLL samples in our cohort displayed discordant VLA-4 and CD38 risk, with either high VLA-4 and low CD38 risk or vice versa. Using particularly such samples, we observed that VLA-4, and not CD38, was responsible for recirculation of CLL cells to murine BM. Human BM infiltration was also significantly higher in patients with high VLA-4 risk but not high CD38 risk. However, both molecules acted as independent prognostic markers. While both VLA-4 and CD38 expression were increased in BM-derived CLL cells, and VLA-4+ and CD38+ subpopulations showed enriched Ki-67 expression, VLA-4 did not contribute to CLL cell protection by stromal cells in vitro.ConclusionsOur data argue for a prominent role of VLA-4 but not CD38 expression in the homing of CLL cells to BM niches and in human BM infiltration,but only a limited role in their protection by stromal cells.

Long intergenic non-coding RNA HOTAIRM1 regulates cell cycle progression during myeloid maturation in NB4 human promyelocytic leukemia cells

“…30,80 Beta-1 integrin VLA-4 (CD49d/CD29) has recently identified functions in hematopoietic cellular proliferation, including stem cell self-renewal, CD34+ cell mobilization, and ex vivo expansion, as well as in hematopoietic and leukemic stem cell homing. [57][58][59][60]81,82 An integrin switch mechanism, through changing proportions of α-5 and α-6 integrins, has also been proposed as the determining factor in the proliferation vs. differentiation decision during primary adipocyte differentiation. 69,70 The current study reports an α-4 to α-X integrin switch that is precisely coordinated with the transit from proliferative phase of cell cycle progression to granulocytic maturation.…”

“…CD49d, the integrin α 4 chain, is the α subunit of the receptor for the endothelial adhesion molecule VCAM-1 and associated with bone marrow homing, proliferation, and cell cycle progression in CD34+ hematopoietic stem and progenitor cells. 43,[57][58][59][60] Its expression is decreased during myeloid differentiation in NB4 and other leukemia cell lines. 43 We validated the significantly retained mRNA level of ITGA4 gene (Fig.…”

Trisomy 12 chronic lymphocytic leukemia cells exhibit upregulation of integrin signaling that is modulated by NOTCH1 mutations

“…24 A similar association has also been shown between high expression of CD49d and increased bone marrow infiltration in human disease, and enhanced bone marrow homing capacity in an in vitro adoptive transfer mouse model. 25 Mechanistically, there is evidence to suggest that while entry of normal B cells into LNs is dependent on LFA-1, CLL cells rely on interactions between VLA-4 and LFA-1 to cross endothelial cell monolayers. 26,27 Taken together, the evidence suggests that VLA-4 plays a more important role than LFA-1 in the migratory function of CLL cells, which is also being borne out in novel models of CLL cell trafficking.…”

ILK Induction in Lymphoid Organs by a TNFα–NF-κB–Regulated Pathway Promotes the Development of Chronic Lymphocytic Leukemia

“…Cells were cultured in RPMI1640 medium supplemented with 10% FCS, 2 mmol/L L-glutamine, and 1% antibiotics. Analysis of the immunoglobulin heavy chain variable (IGHV) mutational status, Zap70, CD38, and CD49d expression, and fluorescence in situ hybridization analysis of chromosomal abnormalities were routinely performed (7,20,21). Zap70 risk was assessed as T/CLL cell expression ratio (22).…”

“…These signals induce proliferation of the otherwise cell cycle-arrested leukemic cells, in line with elevated expression of NF-kB-related molecules, such as the major canonical pathway signaling subunit p65, a molecule suggested as a predictor of clinical outcome in CLL (4)(5)(6). The localization of CLL cells adjacent to these signals is orchestrated by chemokine receptors and adhesion molecules such as the VLA-4 integrin, a heterodimer composed of an a4 (CD49d), and a b1 (CD29) subunit, which we previously identified as a key receptor in CLL homing (7,8). Downstream signaling of integrins relies on adaptor proteins that are recruited to the cytoplasmic domains of their subunits, with a dominant role of the b subunit.…”