Eleftheria Lamprianidou

Lactobacillus casei Exerts Anti-Proliferative Effects Accompanied by Apoptotic Cell Death and Up-Regulation of TRAIL in Colon Carcinoma Cells.

Probiotic microorganisms such as lactic acid bacteria (LAB) exert a number of strain-specific health-promoting activities attributed to their immunomodulatory, anti-inflammatory and anti-carcinogenic properties. Despite recent attention, our understanding of the biological processes involved in the beneficial effects of LAB strains is still limited. To this end, the present study investigated the growth-inhibitory effects of Lactobacillus casei ATCC 393 against experimental colon cancer. Administration of live Lactobacillus casei (as well as bacterial components thereof) on murine (CT26) and human (HT29) colon carcinoma cell lines raised a significant concentration- and time-dependent anti-proliferative effect, determined by cell viability assays. Specifically, a dramatic decrease in viability of colon cancer cells co-incubated with 109 CFU/mL L. casei for 24 hours was detected (78% for HT29 and 52% for CT26 cells). In addition, live L. casei induced apoptotic cell death in both cell lines as revealed by annexin V and propidium iodide staining. The significance of the in vitro anti-proliferative effects was further confirmed in an experimental tumor model. Oral daily administration of 109 CFU live L. casei for 13 days significantly inhibited in vivo growth of colon carcinoma cells, resulting in approximately 80% reduction in tumor volume of treated mice. Tumor growth inhibition was accompanied by L. casei-driven up-regulation of the TNF-related apoptosis-inducing ligand TRAIL and down-regulation of Survivin. Taken together, these findings provide evidence for beneficial tumor-inhibitory, anti-proliferative and pro-apoptotic effects driven by this probiotic LAB strain.

Expression of CD25 antigen on CD34+ cells is an independent predictor of outcome in late-stage MDS patients treated with azacitidine.

Expression of CD25 antigen on CD34+ cells is an independent predictor of outcome in late-stage MDS patients treated with azacitidine

Three-fold higher frequency of circulating chronic lymphocytic leukemia-like B-cell clones in patients with Ph-Myeloproliferative neoplasms.

Philadelphia chromosome-negative Myeloproliferative neoplasms (Ph-MPN) are accompanied by a markedly increased risk for development of chronic lymphocytic leukemia (CLL) compared to the general population. However, the pattern of onset and the biological characteristics of CLL in patients with coexistent Ph-MPN are highly heterogeneous rendering questionable if the above association reflects a causal relationship between the two disorders or merely represents a random event. By analyzing 82 patients with Ph-MPN and 100 age-matched healthy individuals we demonstrate that MPN patients have an almost threefold higher prevalence of, typically low-count, CLL-like monoclonal B lymphocytosis (MBL) compared to normal adults. The clone size remained unaltered during the disease course and unaffected by the administration of hydroxycarbamide, whereas no patient with Ph-MPN/MBL progressed to CLL during a median follow up of 4 years. Monoclonal B cells in Ph-MPN/MBL patients and normal individuals and in four more patients with coexistence of overt CLL and MPN displayed heterogeneous biological characteristics, while the JAK2V617F mutation was absent in isolated lymphocytes from Ph-MPN patients with coexistence of CLL. Despite its clinical and biological variability, the increased incidence of MBL in Ph-MPN patients along with the one reported for CLL further enforces the notion of a shared pathophysiology among the two malignancies via a common genetic link and/or microenviromental interactions.

The Stat3/5 signaling biosignature in hematopoietic stem/progenitor cells predicts response and outcome in myelodysplastic syndrome patients treated with azacitidine

Purpose: Azacitidine is the mainstay of high-risk myelodysplastic syndromes (MDS) therapy, but molecular predictors of response and the mechanisms of resistance to azacitidine remain largely unidentified. Deregulation of signaling via Stat3 and Stat5 in acute myeloid leukemia (AML) is associated with aggressive disease. Numerous genes involved in cell signaling are aberrantly methylated in MDS, yet the alterations and the effect of azacitidine treatment on Stat3/5 signaling in high-risk MDS have not been explored. Experimental Design: We assessed longitudinally constitutive and ligand-induced phospho-Stat3/5 signaling responses by multiparametric flow cytometry in 74 patients with MDS and low blast count AML undergoing azacitidine therapy. Pretreatment Stat3/5 signaling profiles in CD34+ cells were grouped by unsupervised clustering. The differentiation stage and the molecular properties of the CD34+ G-CSF–inducible Stat3/5 double-positive subpopulation were performed by flow cytometry and quantitative real-time PCR in isolated MDS progenitors. Results: The pretreatment Stat3/5 signaling profiles in CD34+ cells correlated strongly with response and cytogenetics and independently predicted event-free survival. We further identified a CD34+ G-CSF–inducible Stat3/5 double-positive subpopulation (DP subset) whose pretreatment levels were inversely associated with treatment response and cytogenetics. The kinetics of the DP subset followed the response to azacitidine and the disease course, whereas its molecular characteristics and cellular hierarchy were consistent with a leukemia propagating cell phenotype. Conclusions: Our findings provide a novel link among Stat3/5 signaling and MDS pathobiology and suggest that the Stat3/5 signaling biosignature may serve as both a response biomarker and treatment target. Clin Cancer Res; 22(8); 1958–68. ©2015 AACR.

Potentially probiotic Lactobacillus strains with anti-proliferative activity induce cytokine/chemokine production and neutrophil recruitment in mice

Lactobacillus pentosus B281 and Lactobacillus plantarum B282 are two Lactobacillus strains previously isolated from fermented table olives. Both strains were found to possess probiotic properties and displayed desirable technological characteristics for application as starters in novel functional food production. In the present study the anti-proliferative and immunostimulatory activities of the two strains were investigated. Firstly, we demonstrated that live L. pentosus B281 and L. plantarum B282 significantly inhibited the growth of human colon cancer cells (Caco-2) in a time- and dose-dependent manner. By employing the air pouch system in mice, we showed that administration of both strains led to a rapid and statistically significant infiltration of leukocytes in the air pouch exudates. The phenotypical characterisation of the recruited immune cells was performed by flow cytometry analysis. We demonstrated that the majority of the infiltrated leukocytes were neutrophils. Finally by using the Mouse Cytokine Array Panel A Detection Antibody cocktail, we showed that both strains induced the expression of granulocyte-colony stimulating factor, interleukin (IL)-1α, IL-1β, IL-6, chemokine (C-X-C motif) ligand (CXCL)-1, chemokine (C-C motif) ligand (CCL)-3, CCL-4, and CXCL-2 and diminished the expression levels of soluble intercellular adhesion molecule, macrophage colony-stimulating factor and metallopeptidase inhibitor 1. Our results showed that both strains display anti-proliferative and immunostimulatory properties equal or even better in some cases than those of established and commonly used probiotic strains. These findings further support the probiotic character of the two strains.

Identification of a Chemoresistant “Oxidative State-Low” Leukemic Subpopulation in CD34+ Human Acute Myeloid Leukemia

Objective: Both normal and malignant stem cells maintain lower levels of reactive oxygen species (ROS), but the redox state in acute myeloid leukemia (AML) has not been thoroughly characterized and the role of ROS in leukemogenesis is still unclear. Herein, we report the identification of a rare but distinct ROSlow subpopulation in primary CD34+ AML samples. Methods: We analysed the ROS state of a number of AML samples by flow cytometry using the redox-sensitive fluorescence dye 2’7;-dichlorodihydrofluorescein diacetate. We FACS-sorted the ROSlow cells and investigated their immunophenotype, in vivo engraftment potential as well as their ability to withstand chemotherapeutic treatment. Results: Compared to the total CD34+ cells the ROSlow subset contained significantly more CMP-like and less GMP-like progenitors and could establish leukemia in NOD/SCID mice. Additionally, ROSlow cells bore a chemoresistant phenotype as they were more quiescent than total CD34+ AML cells, and showed increased in vitro chemoresistance and markedly higher GM-CSF-induced phosphorylation of STAT5. Conclusions: Thus, the ROSlow subpopulation arises as a novel candidate for cell-specific therapeutic targeting in AML. Further studies will help to ascertain the exact role of the ROSlow subset in the pathobiology and clinical management of AML.