scholarly journals Antiproliferative Effect of Green Papaya on Lymphocytic Leukemic Cells

2020 ◽  
Vol 10 (2) ◽  
Author(s):  
Zainab Allqmani ◽  
Alexus Greene ◽  
Haiwen Li ◽  
Rafie Reza ◽  
Andrea R Beyer ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
Lymphocytic Leukemia ◽  
New Drugs ◽  
Gastric Ulcers ◽  
Total Phenolic ◽  
Leaf Extracts ◽  
Jurkat T Cells ◽  
Oxidation Activity ◽  
Water Extracts

Numerous edible plants have been reported to interfere with the carcinogenic process, and therefore, the regular consumption of these plant products may reduce the risk of developing cancer. We investigated the effect of papaya fruit and leaves on the cell proliferation of Jurkat T-lymphocytic and Daudi B-lymphocytic leukemia cells. Cells were treated with aqueous or methanolic extracts from leaves, skin, pulp, and seeds from green papaya. The papaya fractions were tested for total phenolic content, total flavonoids content, and anti-oxidation activity using chemical assays. Cell proliferation was measured using a WST-1 assay. Our data indicate that methanol and water extracts of seeds and leaves contained higher concentrations of total phenolic compounds and higher anti-oxidation activity than that of extracts from skin and pulp. Both methanol and water extracts from leaves and skin potently inhibited the proliferation of leukemic Jurkat T-cells and Daudi B-cells. However, the effect was more potent on Jurkat T-cells, and the leaf extracts were more effective than that of skin extracts. None of the pulp or seed extracts showed inhibitory activity on leukemic cell proliferation. Although papaya leaves are not consumed as a food, leaf extracts have been used for the treatment of various conditions, including dengue and malaria fevers, gastric ulcers, low platelet counts, and cancers of the breast, lung, and cervix. Our data suggest that the consumption of papaya leaf extracts may also be beneficial in preventing and/or treating lymphocytic cancer. Isolation of active compounds from papaya leaves will also help in developing new drugs for cancer treatment.

scholarly journals The protective role of miR-223 in sepsis-induced mortality

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Dan Liu ◽  
Zhiding Wang ◽  
Huijuan Wang ◽  
Feifei Ren ◽  
Yanqin Li ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Cell Proliferation ◽  
T Cells ◽  
Protective Factor ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Negative Control ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Jurkat T Cells

Abstract Lymphocyte apoptosis appears to play an important role in immunodysfunction in sepsis. We investigated the role of miR-223 in cell proliferation and apoptosis to identify potential target downstream proteins in sepsis. We recruited 143 patients with sepsis and 44 healthy controls from the Chinese PLA General Hospital. Flow cytometry was used to sort monocytes, lymphocytes, and neutrophils from fresh peripheral blood. A miR-223 mimic and inhibitor were used for transient transfection of Jurkat T cells. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to assess expression of the miRNAs in cells. Western blot analysis was performed to measure protein expression. We evaluated the cell cycle and apoptosis by using flow cytometry (FCM) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). Expression of miR-223 was significantly higher in the survivor group than in the nonsurvivor group. Multiple linear regression analysis revealed that SOFA scores correlated negatively with miR-223 and monocyte counts, with β coefficients (95% CI) of − 0.048 (− 0.077, − 0.019) and − 47.707 (− 83.871, − 11.543), respectively. miR-223 expression also correlated negatively with the percentage of apoptosis in lymphocytes. The rate of apoptosis in the miR-223 mimic group was significantly lower than that of the negative control, with an adverse outcome observed in the miR-223 inhibitor group. We also found that miR-223 enhanced the proliferation of Jurkat T cells and that inhibiting miR-223 had an inhibitory effect on the G1/S transition. We conclude that miR-223 can serve as a protective factor in sepsis by reducing apoptosis and enhancing cell proliferation in lymphocytes by interacting with FOXO1. Potential downstream molecules are HSP60, HSP70, and HTRA.

scholarly journals Defective interleukin-2 production and responsiveness by T cells in patients with chronic lymphocytic leukemia of B cell variety

Blood ◽  
1986 ◽  
Vol 67 (2) ◽  
pp. 279-284 ◽  
Author(s):  
O Ayanlar-Batuman ◽  
E Ebert ◽  
SP Hauptman
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Proliferative Response ◽  
Interleukin 2 ◽  
Lymphocytic Leukemia ◽  
T Cell Proliferation ◽  
Activated T Cells

Abstract The present studies were designed to investigate the mechanism(s) of the defective T cell proliferative response to various stimuli in patients with B cell chronic lymphocytic leukemia B-CLL. In 14 patients with advanced B-CLL (stage III or IV) we found the T cell response in the autologous (auto) and allogeneic (allo) mixed lymphocyte reaction (MLR) to be 35.7% and 30% of the controls, respectively. Proliferation in the MLR depends upon the production of and response to interleukin 2 (IL 2), a T cell growth factor. IL 2 production in eight B-CLL patients was 22% of the control. The response to IL 2 was measured by the increase in the T cell proliferation in the MLR with the addition of IL 2. T cell proliferation in both the auto and allo MLR of CLL patients was significantly lower than in the controls after the addition of IL 2. The proliferative response of normal T cells to stimulation by CLL B cells was 50% of the control. This latter response was increased to control levels when cultures were supplemented with exogenous IL 2, suggesting that CLL B cells could stimulate IL 2 receptor generation in normal T cells in an allo MLR, but not IL 2 production. The presence of IL 2 receptors on activated T cells was directly determined using anti- Tac, a monoclonal antibody with specificity for the IL 2 receptor. Of the mitogen- or MLR-activated T cells in CLL patients, 6% and 10%, respectively, expressed Tac antigen, whereas identically stimulated control T cells were 60% and 47% Tac+, respectively. Our findings suggest that T cells in B-CLL are defective in their recognition of self or foreign major histocompatibility antigens as demonstrated by their impaired responsiveness in the MLR. Thus, these cells are unable to produce IL 2 or generate IL 2 receptors.

scholarly journals Clinical and cell surface marker characterization of the early phase of chronic lymphocytic leukemia

Blood ◽  
1978 ◽  
Vol 52 (1) ◽  
pp. 25-35 ◽  
Author(s):  
RA Rudders ◽  
JP Howard
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
B Cell ◽  
Clinical Characteristics ◽  
Surface Marker ◽  
Lymphocytic Leukemia ◽  
Surface Markers ◽  
Laboratory Findings ◽  
Absolute Lymphocyte Counts

Abstract The immunologic surface markers on lymphocytes and clinical characteristics of 35 patients with established (stages 0–4) CLL with absolute lymphocyte counts greater than 15,000/cu mm were compared to those of a group of 25 patients with CLL in an early or preleukemic phase (counts of less than 15,000/cu mm). We found a monoclonal B cell proliferation in most cases in the latter group, in spite of the paucity of clinical and laboratory findings. Furthermore, early CLL can readily be distinguished from benign lymphocytosis by surface marker criteria. In untreated CLL, surface marker characteristics are stable with time and predominantly reflect expansion of clones expressing only B cell markers; however, small increase of blood T cells are often seen. Surface markers are a simple and clinically useful tool for definding and characterizing the preleukemic phase of CLL and its ultimate progression to established CLL.

scholarly journals Allelopathic effects of Rhynchosia capitata on germination and seedling growth of mungbean

2013 ◽  
Vol 31 (3) ◽  
pp. 501-509 ◽  
Author(s):  
H.H. Ali ◽  
A. Tanveer ◽  
M.A. Nadeem ◽  
M.M. Javaid ◽  
M.S. Kashif ◽  
...  
Keyword(s):  
Phenolic Acids ◽  
Seedling Growth ◽  
Leaf Extract ◽  
Water Soluble ◽  
Total Phenolic ◽  
Leaf Extracts ◽  
Seedling Vigour ◽  
Water Extracts ◽  
Whole Plant ◽  
Vigour Index

Experiments were conducted to evaluate the allelopathic influence of Rhynchosia capitata on germination and seedling growth of mungbean (Vigna radiate) along with identification of the phytotoxic substances responsible for this activity. Water extracts of root, shoot, leaf, fruit and whole plant were prepared by soaking them in water in a ratio of 1:20 (w/v) for 24 h. All the extracts affected germination and seedling growth of mungbean, but higher inhibition was seen with R. capitata leaf water extracts. A linear decrease in the germination characteristics of mungbean was observed with the decrease in the concentration of leaf extract from 5% to 1%. The soil-incorporated residues (1-4% w/w) of R. capitata stimulated the growth of root and hypocotyl at low concentrations, while it inhibited their growth at higher concentrations. Rhynchosia capitata soil-incorporated residues (4% w/w) significantly reduced the seedling vigour index of mungbean in addition to their significant effect on total germination. A significant amount of water-soluble phenolic acids were found in R. capitata plant extracts. The content of total phenolic acids was higher in the leaf extract compared to that of the stem, fruit or root extracts. Two phenolic acids including vanillic acid and 4‑(hydroxymethyl) benzoic acid were found in R. capitata leaf extracts.

Chronic Lymphocytic Leukemia Cells Acquire a Regulatory B-Cell Phenotype Modified By PD1 Signaling

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3319-3319 ◽  
Author(s):  
Shimrit Ringelstein-Harlev ◽  
Irit Avivi ◽  
Shoham Shivtiel-Arad ◽  
Tami Katz
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Immune Responses ◽  
B Cell ◽  
Immune Modulation ◽  
Lymphocytic Leukemia ◽  
T Cell Proliferation ◽  
Cell Contact

Abstract Introduction: Chronic lymphocytic leukemia (CLL) cells utilize several mechanisms of survival, some propagating proliferation and preventing apoptosis through intrinsic cell cycle signals, and others suppressing anti-tumor immune responses. Patients often present with a predominant population of regulatory T-cells (Tregs), and general features of T-cell exhaustion. Given the unique phenotype of CLL cells and the observed T-cell abnormalities we hypothesized that these cells function as regulatory B-cells (Bregs). Bregs, mostly explored in the autoimmune disease setting, produce interleukin-10 (IL10), which mediates attenuation of effector T-cell responses and enhances regulatory activity. These features have also been suggested to be responsible for weakening of anti-tumor immune responses. Breg activation requires stimulation of various combinations of Toll-like receptors (TLRs), the B-cell receptor (BCR) and CD40. Our previous studies have demonstrated that TLR9-stimulated CLL cells "acquire" Breg markers as well as PD1 and PDL1, which, while not being classic Breg discriminators, are established players in immune modulation. Moreover, such stimulation resulted in inhibition of proliferation of autologous T-cells. The current study aimed to further explore the regulatory characteristics of CLL cells focusing on additional suppressive mechanisms that may have a role in CLL immune evasion, particularly, the PD1/PDL1 axis. Methods: B-cells were isolated from peripheral blood mononuclear cells (PBMCs) of untreated CLL patients (Rai stages 0-IV). These B-CLL cells were stimulated with TLR-9 agonist (ODN) or CD40 ligand (CD40L) followed by their co-culture with isolated autologous CD4+ T cells. The regulatory features of B-CLL cells were studied by testing their effect on T cells. Their proliferation was evaluated using the CFSE method following stimulation with anti-CD3/CD28 antibodies and IL2; induction of Tregs (CD4+CD25highFoxp3+ population) was assessed by FACS analysis. The involvement of the PD1/PDL1 axis was examined by incubating B-cells with antiPD1 neutralizing antibodies prior to co-culture. Cell contact dependence was evaluated by plating B-cells in hanging cell culture inserts denying B and T cell contact while allowing flow of small soluble molecules. Results: CLL cells stimulated with ODN or CD40L, induced a significant increase in Tregs: 1.35±0.1-fold (p=0.03, N=12) for ODN and 1.7±0.2-fold (p=0.008, N=14) for CD40L, occurring in 68% and 80% of patients, respectively, while co-culture with unstimulated B-CLL cells did not result in the expansion of the Treg population. Treg induction was observed only under contact conditions (N=5), suggesting that this regulatory function requires cell-to-cell contact and cannot be carried out solely by secreted factors like IL10. Neutralization of PD1 on CLL B-cells affects both Treg induction and T-cell proliferation. Following CD40L stimulation, a 1.3-fold reduction in Treg percentage was observed when PD1 signaling was blunted (N=10). In contrast, PD1 blockage of ODN-stimulated CLL cells did not reduce Treg induction; however, it did adversely affect inhibition of T-cell proliferation (10%-decrease in inhibited T-cells; N=6). Conclusions: CLL cells "acquire" a Breg phenotype and function, inhibiting T-cell proliferation and inducing Tregs. These properties, while working together to promote immune regulation and cancer evasion, are elicited by different ligands in the cell environment and are likely to be mediated via separate pathways. The involvement of B-cell-associated PD1 in the induction of Tregs and inhibition of T-cell proliferation suggests a biologic role of PD1 signaling in CLL cells, strengthening the Breg phenotype. The current study has shown that CLL cells recruit several mechanisms operating cooperatively to support immune modulation and promote their survival. Disclosures No relevant conflicts of interest to declare.

Adenosine Signaling Mediates Hypoxic Responses in the Chronic Lymphocytic Leukemia Microenvironment

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4145-4145
Author(s):  
Sara Serra ◽  
Davide Brusa ◽  
Tiziana Vaisitti ◽  
Roberta Buonincontri ◽  
Valentina Audrito ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Lymphocytic Leukemia ◽  
Nucleoside Transporters ◽  
Leukemic Cells ◽  
T Cell Proliferation ◽  
A2a Adenosine Receptor ◽  
Hypoxic Conditions ◽  
A2a Receptor

Abstract Extracellular adenosine generated from ATP/ADP through the concerted action of the ectoenzymes CD39 and CD73 elicits potent cytoprotective and immunosuppressive effects mediated by type-1 purinergic receptors. Chronic lymphocytic leukemia (CLL) cells expressing the ectoenzymes CD39 and CD73 can actively produce adenosine, activating an autocrine adenosinergic axis that supports engraftment of leukemic cells in a growth-favorable environment. These effects are mediated by the A2A adenosine receptor, which inhibits chemotaxis and limits spontaneous and drug-induced apoptosis of CLL cells. Following the reported cross-talk between hypoxia and adenosine, we tested the hypothesis of a functional interplay between the adenosinergic axis and hypoxic signals in the CLL microenvironment. Results indicate that culture of CLL cells under hypoxic conditions, such as those observed in lymph nodes from CLL patients, boosts adenosine production, mainly because of the significant increase in the mRNA and protein levels of CD73, the rate-limiting enzyme in adenosine synthesis. CLL also underwent a robust up-regulation of CD26, which functions as an adenosine-deaminase scaffold protein, in keeping with the hypothesis that extracellular nucleotides enter a scavenging pathway, with conversion to inosine and re-uptake by the leukemic cells. Confirmation was obtained using HPLC assays, which showed increased inosine generation under hypoxia. Consistently, expression of membrane nucleoside transporters was also significantly up-regulated. However, hypoxic CLL cells also expressed high levels of the A2A adenosine receptor, which delivered cytoprotective signals and which supported CLL proliferation in response to TLR signaling. Attention was then focused on the stromal and T cell compartments, which are critical to the formation and maintenance of the leukemic niche. Hypoxia enhanced differentiation of circulating monocytes into nurse-like cells, macrophages of the M2 type playing an essential role in nurturing leukemic cells. The enhancement of NLC differentiation under hypoxic conditions relied, at least in part, on the activation of A2A: its engagement by a pharmacological agonist favored NLC generation, with overexpression of indoleamine 2,3-dioxygenase (IDO) and of the M2 macrophage markers CD163 and CD206. Moreover, activation of A2A induced secretion of immunomodulatory cytokines, such as IL-6, IL-10 and CCL18, while pharmacological blockade of A2A under hypoxia prevented NLC differentiation, expansion, expression of immunosuppressive molecules and secretion of cytokines and chemokines. In the T cell compartment, hypoxic cultures were followed by the sharp up-regulation of A2A, without significantly affecting the enzymes that generate adenosine, which were anyway restricted to the regulatory T cell (Treg) compartment. Co-cultures of T lymphocytes and CLL cells under hypoxia resulted in a dramatic decrease of T cell proliferation, partially rescued by A2A receptor antagonists. Furthermore, hypoxic T cells underwent a metabolic switch, with increased expression of nucleoside transporters and enzymes involved in glucose metabolism, suggesting a Warburg effect. This was accompanied by the differentiation of a population of Tr1 cells, characterized by the expression of LAG3 and CD49b and by the secretion of high levels of IL-10 and VEGF. Expression of the PD-1 immuno-inhibitory receptor was enhanced in hypoxic T cells, suggesting that multiple inhibitory mechanisms are activated. We also observed expansion of classical Tregs, defined on the basis of a CD4+/CD25high/CD127low/foxp3+ phenotype. Blockade of the A2A receptor prevented this phenotype, partially restoring T cell proliferation and immune competence. Together, these findings indicate that the adenosinergic and hypoxic axes synergize in shaping the CLL niche, suggesting that pharmacological inhibition of the adenosinergic signals may counteract some of the effects mediated by an hypoxic environment, contributing to disrupt the leukemic niche and to restore the immune system. Disclosures Gaidano: Celgene: Research Funding; MorphoSys; Roche; Novartis; GlaxoSmithKline; Amgen; Janssen; Karyopharm: Honoraria, Other: Advisory boards.

scholarly journals Defective interleukin-2 production and responsiveness by T cells in patients with chronic lymphocytic leukemia of B cell variety

Blood ◽  
1986 ◽  
Vol 67 (2) ◽  
pp. 279-284 ◽  
Author(s):  
O Ayanlar-Batuman ◽  
E Ebert ◽  
SP Hauptman
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Proliferative Response ◽  
Interleukin 2 ◽  
Lymphocytic Leukemia ◽  
T Cell Proliferation ◽  
Activated T Cells

The present studies were designed to investigate the mechanism(s) of the defective T cell proliferative response to various stimuli in patients with B cell chronic lymphocytic leukemia B-CLL. In 14 patients with advanced B-CLL (stage III or IV) we found the T cell response in the autologous (auto) and allogeneic (allo) mixed lymphocyte reaction (MLR) to be 35.7% and 30% of the controls, respectively. Proliferation in the MLR depends upon the production of and response to interleukin 2 (IL 2), a T cell growth factor. IL 2 production in eight B-CLL patients was 22% of the control. The response to IL 2 was measured by the increase in the T cell proliferation in the MLR with the addition of IL 2. T cell proliferation in both the auto and allo MLR of CLL patients was significantly lower than in the controls after the addition of IL 2. The proliferative response of normal T cells to stimulation by CLL B cells was 50% of the control. This latter response was increased to control levels when cultures were supplemented with exogenous IL 2, suggesting that CLL B cells could stimulate IL 2 receptor generation in normal T cells in an allo MLR, but not IL 2 production. The presence of IL 2 receptors on activated T cells was directly determined using anti- Tac, a monoclonal antibody with specificity for the IL 2 receptor. Of the mitogen- or MLR-activated T cells in CLL patients, 6% and 10%, respectively, expressed Tac antigen, whereas identically stimulated control T cells were 60% and 47% Tac+, respectively. Our findings suggest that T cells in B-CLL are defective in their recognition of self or foreign major histocompatibility antigens as demonstrated by their impaired responsiveness in the MLR. Thus, these cells are unable to produce IL 2 or generate IL 2 receptors.

Chronic Lymphocytic Leukemia Cells Exhibit Inhibitory Properties of Regulatory B Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3874-3874
Author(s):  
Shimrit Ringelstein-Harlev ◽  
Irit Avivi ◽  
Lina Bisharat ◽  
Tamar Katz
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Fold Increase ◽  
Lymphocytic Leukemia ◽  
T Cell Proliferation ◽  
Cell Contact ◽  
Stimulation Of

Abstract Abstract 3874 Background: Chronic lymphocytic leukemia (CLL) is a mature B-cell malignancy, characterized by distinct immune suppression rendering both tumor cells and invading pathogens invisible to the immune system. However, CLL cells also display profound immune sensitivity as proven by long-term remissions achieved with allogeneic bone marrow transplantation. Many phenotypic properties of B-CLL cells resemble a subset of B-cells, studied mostly in autoimmunity and termed regulatory B cells (Bregs). Bregs are thought to suppress CD4+ T-cell mediated immune responses, directly through cell contact and indirectly through inhibitory cytokines. This study aims to define whether malignant B-CLL cells exhibit Breg suppressive properties, contributing to immune dysfunction in this disease. Methods: B-cells were isolated from peripheral blood mononuclear cells (PBMCs) of untreated CLL patients (Rai stages 0-IV) using immunomagnetic separation (STEMCELL technologies). Naïve cells and those stimulated with B-cell activators TLR-9 agonist or CD40Ligand (CD40L) were analyzed by FACS for Breg phenotypic markers and intracellular IL-10. Additionally, B-CLL cell effects on autologous CD4+ T cells (isolated by immunomagnetic beads; Miltenyi Biotec) were studied. T-cells were stimulated with anti-CD3/CD28 antibodies and IL-2, and exposed to B-cells either directly or through hanging cell culture inserts (Millipore) preventing physical cell-cell contact. T-cell proliferation was assessed using the carboxyfluorescein diacetate succinimidyl ester (CFSE) method and phenotype was analyzed by FACS. Results: B-cell phenotype was studied in 11 patients. Breg markers (CD5, CD38, CD25 and intracellular IL-10) as well as inhibitory molecules PD-1 and PDL-1 were expressed at high levels on B-CLL cells (62%, 37%, 50%, 52%, 29%, 61%, respectively), although not every patient expressed all markers. These expression levels were higher than those reported for normal peripheral blood B-cells. TLR-9 stimulation of B-CLL cells resulted in a 5.7-fold increase in expression of CD25 in 77% of patients. Increments were also observed in IL-10 (1.9-fold; 62% of patients), PDL-1 (1.96-fold; 83% of patients) and PD-1 (2.19-fold; 57% of patients). Of 13 patients whose T-cell proliferation potential was evaluated after exposure to B-CLL cells, proliferation was induced in only 69%; in the other 31% (4 patients) no proliferation was observed; moreover, inhibition was demonstrated in one of them. Among the former group only 33% of patients expressed CD25 on their B-cells, whereas within the latter group, 75% of patients' B-cells were CD25-positive. Stimulation of B-CLL cells with TLR-9 markedly increased their inhibitory capacity (72% of 11 patients tested), while CD40L stimulation caused a weaker effect (50% of 6 patients tested). T-cell proliferation remained unchanged when evaluated using a Transwell system versus a contact system, as demonstrated in 3 of 4 experiments. T-cells exposed to B-CLL cells altered the ratio of CD25high vs. CD25low T-cells in favor of CD25 high cells (2.44-fold increase for stimulation with naïve B-CLL cells, 4.94-fold increase with TLR-9 stimulated cells; in all the 5 tested patients). Conclusions: Previously identified Breg markers as well as PD-1 and PDL-1 were highly expressed in B-CLL cells, supporting the role of these cells in shaping an immune tolerant environment, enabling tumor growth. Stimulation of B-CLL cells with TLR-9 agonist enhanced this phenotype and resulted in consistent inhibition of T-cell proliferation, likely to be independent of cell-to-cell contact. These findings demonstrate the presence of Breg features within the CLL clone. The observed alterations in CD4+CD25+ T-cell populations after exposure to B-CLL cells suggest induction of T-regulatory cells, another mechanism supposedly used by Bregs for immune suppression. The enhancement of Breg properties in B-CLL cells following B-cell activation can serve as a platform for further studies of the innate regulatory mechanisms utilized by tumor cells. Disclosures: No relevant conflicts of interest to declare.

KCa3.1 Blockers Inhibit Cell Proliferation in Chronic Lymphocytic Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3887-3887
Author(s):  
Eva M Groessinger ◽  
Lukas Weiss ◽  
Elisabeth Hinterseer ◽  
Judith Schmoelzer ◽  
Karin Oberascher ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Peripheral Blood ◽  
Lymphocytic Leukemia ◽  
K Channel ◽  
Relative Reduction ◽  
Rt Pcr ◽  
Ki 67

Abstract Abstract 3887 Potassium (K)-channels play an important role in regulating cell proliferation by maintenance of the membrane potential and subsequent Ca2+ signaling. Out of 80 known human K-channel genes only the voltage gated K-channel Kv1.3 and the calcium-gated K-channel KCa3.1 are expressed in lymphocytes, with expression levels varying greatly depending on lymphocyte maturation and activation status (for review see Cahalan MD, Chandy KG, Immunol Rev. 2009). Accordingly, proliferation of various lymphocyte subtypes can be inhibited by blockade of the respective predominant K-channel. As the modulation of K-channel expression on malignantly transformed lymphocytes and their potential as therapeutic targets has been largely overlooked, we characterized the expression and function of Kv1.3 and KCa3.1 in Chronic Lymphocytic Leukemia (CLL). Primary cells from unselected CLL-patients were isolated from peripheral blood mononuclear cells (PBMCs). Comparison of Kv1.3 and KCa3.1 levels on unstimulated CLL-cells versus PMA/ionomycin-activated CLL-cells revealed a significant reduction in the Kv1.3/KCa3.1 ratio (n=31, 1.526 vs. 0.9054, p=0.0005), as evidenced on mRNA and protein levels by RT-PCR and patch clamp analysis, respectively. Stimulation of CLL-cells with enriched and activated autologous CD4+ T-cells resulted in higher CLL-cell activation as measured by CD80/86 expression, and an even more pronounced reduction of the Kv1.3/KCa3.1 ratio. This stimulation protocol also effectively induced CLL-cell proliferation as verified by Ki-67 expression and CFSE dilution via flow cytometric measurement. Highly activated and/or proliferating CLL-cells consistently up-regulated KCa3.1 (RT-PCR: Ki-67 n=5, p=0.0013; CFSE n=5, p=0.0436; immunofluorescence (IF) staining - n=4, p=0.0121), whereas Kv1.3 was fairly low. Consistent with our in vitro data, CLL-cells in lymph node and bone marrow, believed to be primary sites of CLL-proliferation in vivo, were highly positive for KCa3.1 channels in contrast to CLL-cells from the peripheral blood as revealed by IF staining on paraffin-embedded tissue sections. In light of the significantly increased KCa3.1-expression on activated and proliferating CLL-cells, we investigated whether specific blockade of KCa3.1 could inhibit CLL-cell proliferation. CLL-cells in PBMCs were pre-stimulated by co-culture with CD40L expressing (murine) fibroblasts for 24 hours, and were treated with highly specific blockers for KCa3.1 (TRAM-34 or Clotrimazole) or Kv1.3 (PAP-1 or Psora-4) prior to addition of α-CD3/CD28 beads to activate autologous T-cells. KCa3.1 blockade could effectively diminish CLL-cell cycle entry in all samples investigated (TRAM-34: n=12, p<0.0001; Clotrimazole: n=5, p=0.0625) with a mean relative reduction in Ki-67+ cells of 52% (SD=1.56) for TRAM-34 (see Figure left) and 53% (SD=1.11) for Clotrimazole. This antagonizing effect of TRAM-34 was clearly dose-dependent (n=10) without affecting CLL-cell viability (see Figure right) nor activation. Viability, activation and proliferation of T-cells and fibroblasts present in the co-culture system were not affected by TRAM-34. Blockade of Kv1.3 did not reduce proliferation in CLL-cells. In summary, we showed that CLL-cells exhibit significant changes in their K-channel constitution following activation and proliferation, analogous to healthy B-cells. Notably, in vitro CLL-cell proliferation was effectively inhibited by highly specific KCa3.1 blockers. Thus far in vitro testing of potential CLL-drugs has been primarily performed on G0-arrested CLL-cells, sometimes in co-culture with stromal cells to enhance their viability. Our approach attempts to specifically target proliferating CLL-cells, presumably the most relevant CLL-cell fraction contributing to disease progression. Given their low toxicity profile, KCa3.1 blockers could represent a promising therapeutic option in CLL. Disclosures: No relevant conflicts of interest to declare.

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