Monocytes/macrophages but not T lymphocytes are the major targets of the CCL3/CCL4 chemokines produced by CD38(+)CD49d(+) chronic lymphocytic leukaemia cells

CD73-generated extracellular adenosine in chronic lymphocytic leukemia creates local conditions counteracting drug-induced cell death

Abstract Extracellular adenosine (ADO), generated from ATP or ADP through the concerted action of the ectoenzymes CD39 and CD73, elicits autocrine and paracrine effects mediated by type 1 purinergic receptors. We have tested whether the expression of CD39 and CD73 by chronic lymphocytic leukemia (CLL) cells activates an adenosinergic axis affecting growth and survival. By immunohistochemistry, CD39 is widely expressed in CLL lymph nodes, whereas CD73 is restricted to proliferation centers. CD73 expression is highest on Ki-67+ CLL cells, adjacent to T lymphocytes, and is further localized to perivascular areas. CD39+/CD73+ CLL cells generate ADO from ADP in a time- and concentration-dependen…

2.35 CD73-Generated Extracellular Adenosine Creates Microenvironmental Conditions Favoring Growth and Survival of Chronic Lymphocytic Leukemia Cells

Abstract Abstract 621 CD39 (ecto-nucleoside-triphosphate-diphosphohydrolase-1) and CD73 (5'-nucleotidase) are surface enzymes with extracellular catalytic sites. CD39 hydrolyses ATP/ADP to AMP, which is then converted to adenosine (ADO) by CD73. Once ADO is released in the extracellular milieu, it may re-enter the cell or engage different types of purinergic receptors, eliciting potent autocrine and paracrine cytoprotective, anti-inflammatory and immunosuppressive effects. Several lines of evidence suggest that the tumor microenvironment is marked by increased turnover of extracellular nucleotides and nucleosides, as well as by upregulation of ecto-enzymes that dismantle them. These alterat…

A variant of the LRP4 gene affects the risk of chronic lymphocytic leukaemia transformation to Richter syndrome

Richter syndrome (RS) represents the transformation of chronic lymphocytic leukaemia (CLL) to aggressive lymphoma. Risk factors of CLL transformation to RS are only partly known. We explored the role of the host genetic background as a risk factor for RS occurrence. Forty-five single nucleotide polimorphisms (SNPs) known to be relevant for CLL prognosis were genotyped in a consecutive cohort of 331 CLL, of which 21 had transformed to RS. After correcting for multiple testing and adjusting for previously reported RS risk factors, the LRP4 rs2306029 TT variant genotype was the sole SNP independently associated with a higher risk of RS transformation (Hazard Ratio: 4·17; P = 0·001; q = 0·047).…

The monocytic population in chronic lymphocytic leukemia shows altered composition and deregulation of genes involved in phagocytosis and inflammation.

Macrophages reside in tissues infiltrated by chronic lymphocytic leukemia B cells and the extent of infiltration is associated with adverse prognostic factors. We studied blood monocyte population by flow cytometry and whole-genome microarrays. A mixed lymphocyte reaction was performed to evaluate proliferation of T cells in contact with monocytes from patients and normal donors. Migration and gene modulation in normal monocytes cultured with CLL cells were also evaluated. The absolute number of monocytes increased in chronic lymphocytic leukemia patients compared to the number in normal controls (792 +/- 86 cells/mu L versus 485 +/- 46 cells/mL, P=0.003). Higher numbers of non-classical CD…

Host Genetic Background and Risk of Richter Syndrome: The Genotype of LRP4 Is An Independent Predictor of Chronic Lymphocytic Leukemia Transformation to Aggressive Lymphoma.

Abstract Abstract 2340 Poster Board II-317 Richter syndrome (RS) represents the transformation of chronic lymphocytic leukemia (CLL) to aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). Mechanisms and risk factors of CLL transformation to RS are known only in part. This study aimed at exploring the role of the host genetic background in RS transformation and was based on a consecutive series of 331 CLL, of which 21 had transformed to RS (all clonally related to the CLL clone). Twenty eight additional cases of clonally related RS were also collected for validation purposes. Using an educated guess approach, SNPs were selected according to the following criteria: i) re…

A novel role of the CX3CR1/CX3CL1 system in the cross-talk between chronic lymphocytic leukemia cells and tumor microenvironment

Several chemokines/chemokine receptors such as CCR7, CXCR4 and CXCR5 attract chronic lymphocytic leukemia (CLL) cells to specific microenvironments. Here we have investigated whether the CX(3)CR1/CX(3)CL1 axis is involved in the interaction of CLL with their microenvironment. CLL cells from 52 patients expressed surface CX(3)CR1 and CX(3)CL1 and released constitutively soluble CX(3)CL1. One third of these were attracted in vitro by soluble CX(3)CL1. CX(3)CL1-induced phosphorylation of PI3K, Erk1/2, p38, Akt and Src was involved in induction of CLL chemotaxis. Leukemic B cells upregulated CXCR4 upon incubation with CX(3)CL1 and this was paralleled by increased chemotaxis to CXCL12. Akt phosp…

CCL3 and CCL4, the Major Chemokines Produced by CD38+ Chronic Lymphocytic Leukemia Cells, Facilitate Microenvironmental Interactions of Neoplastic Cells Via the CD49d/VCAM Pair.

Abstract CD38, a negative prognostic marker for patients with CLL, has been demonstrated to be a key molecule in the interactions occurring in the context of tumor microenvironment, mediating both survival and migratory signals for CLL cells. By taking advantage of gene expression profiling studies (GEP) comparing 11 CD38pos (CD38>30%) and 15 CD38neg (CD38<10%) CLLs, we identified as over-expressed in CD38pos CLL cells: i) genes for the two C-C chemokines CCL3 and CCL4 (median-log difference, MLD-CCL3= 3.5; MLD-CCL4=4.4); real-time quantitative PCR (RTQ-PCR) of selected cases confirmed GEP results; ii) the gene for CD49d (MLD=4.4); a high correlation between CD38 and CD49d pro…

Active caspase-3 detection to evaluate apoptosis induced by Verbena officinalis essential oil and citral in chronic lymphocytic leukaemia cells

Verbena officinalis L., Verbenaceae, commonly known as vervain, is a plant widely used in medicine. Despite of its widespread use in different traditional practices, the mechanisms of pharmacological actions of the plant and its volatile oil are still unclear. We evaluated the pro-apoptotic activity of V. officinalis essential oil and of its main component, citral, on lymphocytes collected from ten patients with chronic lymphocytic leukaemia (CLL), a disease in which a faulty apoptotic mechanism is still retained one of the primary pathogenic events, by adding to treated mononuclear cells, annexin-V, propidium iodide, and CD19. Apoptosis was also evaluated using anti-active-caspase-3 monocl…

Monocytes/Macrophages Are the Major Targets of the CCL3 Chemokine Produced by CD38(+)CD49d(+) Chronic Lymphocytic Leukemia Cells

Abstract Abstract 2350 Poster Board II-327 Introduction: CD38 and CD49d are associated negative prognosticators in chronic lymphocytic leukemia (CLL). Recent gene expression profiling studies comparing CLL cases expressing low versus high levels of CD38 and CD49d, identified CCL3 as a gene upregulated by CD38+CD49d+ CLL. The release of CCL3 by cultured CLL cells was also demonstrated upon CD38 triggering, and CCL3 protein was found in CLL cells from bone marrow biopsies (BMB) of CD38+ cases (Zucchetto et al., Cancer Res, 2009; 69:4001-9). Given the role of CCL3 as potent chemoattractant for different cell types, we aimed at identifying the major targets of CCL3, as produced by CD38+CD49d+ C…

CD38/CD31, the CCL3 and CCL4 chemokines, and CD49d/vascular cell adhesion molecule-1 are interchained by sequential events sustaining chronic lymphocytic leukemia cell survival.

AbstractCD38 and CD49d are associated negative prognosticators in chronic lymphocytic leukemia (CLL). Despite evidence that both molecules are involved in interactions occurring between CLL and normal cells in the context of CLL-involved tissues, a functional link is still missing. Using gene expression profiles comparing CD38+CD49d+ versus CD38−CD49d− CLL cells, we showed overexpression of the CCL3 and CCL4 chemokines in cells from the former group. These chemokines were also up-regulated by CD38 signals in CLL; moreover, CCL3 was expressed by CLL cells from bone marrow biopsies (BMB) of CD38+CD49d+ but not CD38−CD49d− cases. High levels of CCR1 and, to a lesser extent, CCR5, the receptors…