Molecular basis of chronic lymphocytic leukemia diagnosis and prognosis

NOD2 silencing promotes cell apoptosis and inhibits drug resistance in chronic lymphocytic leukemia by inhibiting the NF-κB signaling pathway

Recent years have witnessed increasing studies on the effect of epigenetic silencing of genes in the progression of chronic lymphocytic leukemia (CLL). This study investigates whether the nucleotide binding oligomerization domain containing 2 (NOD2) participates in the cell apoptosis and drug resistance of CLL cells. Cells were treated with adriamycin (ADR), etoposide, aclacinomycin and daunorubicin. After treatment, drug resistance and cell proliferation were examined to detect the inhibitory effect of ADR on cell proliferation; flow cytometry to identify ADR accumulation, the cell cycle distribution and apoptosis after transfection, and rhodamine 123 accumulation and efflux tests to assess P-glycoprotein (P-gp) function. NOD2 silencing or inhibition of the nuclear factor kappa-B (NF-κB) signaling pathway suppressed the multidrug resistance level in CLL, the inhibition rate, and cell proliferation caused by ADR at concentrations of approximately 0.25-1.5 μmol/L. Greater accumulation of ADR was observed in the CLL-AAT cell line than in the CLL-AAT/A02 cell line, but NOD2 silencing or inhibition of the NF-κB signaling pathway further increased the accumulation of ADR drugs in the CLL-AAT cell line and inhibited the drug efflux pump function of P-gp. Additionally, NOD2 silencing or NF-κB signaling pathway inhibition increased the apoptotic rate. The results of this study indicate that NOD2 promotes cell apoptosis and reduces the drug resistance of CLL by inhibiting the NF-κB signaling pathway.

A novel necroptosis signature for predicting survival in lung adenocarcinoma

BACKGROUND

To explore the necroptosis-related genes (NRGs) signature and its predictive values in lung adenocarcinoma (LUAD).

METHODS

The training cohort consisted of tumor samples from The Cancer Genome Atlas, and the validation set comprised data from the Gene Expression Omnibus. Univariate and multivariate Cox regression analyses were applied to identify the prognostic NRG signature as an independent molecular indicator. Correlation analysis was used for the association assessment between the NRG signature and immune checkpoint molecules.

RESULTS

NRGs involved in necroptosis and immune NOD-like receptor signaling. The NRG signature based on eight NRGs can divide tumors into high-risk and low-risk groups, which was significantly associated with worse survival. Multivariate Cox regression analysis showed that this NRG signature remained an independent prognostic indicator. Stratification analyses demonstrated that this NRG signature was still effective for predicting survival in each stratum of age, gender, and tumor stage. The ROC curve showed a good predictive ability using the NRG signature in the validation cohort (AUC = 0.81). The NRG signature was related to immune checkpoint molecules PD - 1, PD-L1, and PD-L2.

CONCLUSIONS

The NRG signature could be a novel predictor of the prognosis and may become a potential therapeutic target in LUAD.

Immunotherapy approaches for hematological cancers

Hematological cancers such as leukemia, lymphoma, and multiple myeloma have traditionally been treated with chemo and radiotherapy approaches. Introduction of immunotherapies for treatment of these diseases has led to patient remissions that would not have been possible with traditional approaches. In this critical review we identify main disease characteristics, symptoms, and current treatment options. Five common immunotherapies, namely checkpoint inhibitors, vaccines, cell-based therapies, antibodies, and oncolytic viruses, are described, and their applications in hematological cancers are critically discussed.

miR-197, miR-26a and miR-27a analysis in chronic lymphocytic leukemia

Aims: Chronic lymphocytic leukemia (CLL) involves the proliferation and increase of B-lymphocytes in the peripheral blood, bone marrow and lymphoid organs. This study evaluated the microRNAs miR-197, miR-26a and miR-27a as potential biomarkers for CLL. Patients & Methods: Eighty-two patients with CLL and 62 control subjects (CT) were investigated for these targets, using quantitative PCR (qPCR). Results: A significant reduction of all microRNAs was observed in CLL compared to the controls (p < 0.001). Significant negative correlations were observed for the clinical staging groups. After adjusting for multiple logistic regression analysis, miR-197 and miR-26a remained as possible independent risk factors related to the CLL. Conclusions: Our data indicated good performance of this microRNAs as potential biomarkers in CLL.

Frequency, variations, and prognostic implications of chromosome 14q32 deletions in chronic lymphocytic leukemia

The clinical implications of deletions within chromosome 14q32 in CLL pathogenesis remain unclear. We examined the frequency of 14q32 deletions among CLL cases by karyotype and FISH, categorized the variation using genomic microarray, and assessed the prognostic impact by time-to-first-treatment (TTFT) analysis. A 14q32 abnormality was detected in 35 % (245/698) of cases, with the majority containing a 5' partial telomeric 14q32 deletion. These deletions within the IGH variable region (35/40) ranged from 236 kb to 1.4 Mb involving FAM30A, ADAM6, LINC00226, and LINC00221. The 214 kb minimum deleted region implicated in CLL pathogenesis encompassed LINC00221. Cases with a 14q32 deletion had a shorter median TTFT compared to cases with a sole deletion/nullisomy 13q, a good prognostic indicator, and longer than cases with a sole deletion of 11q or 17p, conferring an unfavorable prognosis. This investigation underscores the importance of comprehensive testing to apprehend the implications of 14q32 deletions in CLL.

Autophagy regulation and its role in normal and malignant hematopoiesis

Autophagy, the molecular machinery of self-eating, plays a dual role of a tumor promoter and tumor suppressor. This mechanism affects different clinical responses in cancer cells. Autophagy is targeted for treating patients resistant to chemotherapy or radiation. Limited reports investigate the significance of autophagy in cancer therapy, the regulation of hematopoietic and leukemic stem cells and leukemia formation. In the current review, the role of autophagy is discussed in various stages of hematopoiesis including quiescence, self-renewal, and differentiation.

CD markers variations in chronic lymphocytic leukemia: New insights into prognosis

Chronic lymphocytic leukemia (CLL) is one of the most commonly occurring adult leukemias that is associated with clonal accumulation of mature apoptosis-resistant B-cells in bone marrow, peripheral blood, and specific tissues. Different pathogenesis factors can contribute to the aggression of the clinical course in this disease. Cytogenetic abnormalities and surface biomarkers of neoplastic CLL cells can be effective in the outcome of CLL, and the examination of changing CD markers expressions in the progression of CLL can be related to the prognosis of this disease. Changing expression levels of CD markers on lymphocytes and other cells in CLL patients can play a role in the aggressive clinical outcomes such as organomegaly, immunodeficiency, and advanced disease stages through their interaction with CLL microenvironment. Given the involvement of CD markers in the pathogenesis of CLL, it can be stated that recognizing the expression changes of CD markers in the cells involved in CLL can be a proper approach to evaluate prognosis among these patients.

NOTCH1, SF3B1, MDM2 and MYD88 mutations in patients with chronic lymphocytic leukemia

Mutations in certain genes have been suggested to be associated with the pathogenesis of chronic lymphocytic leukemia (CLL), which is the most common leukemia in adults. In a case-control study, 100 patients with CLL and 105 healthy individuals were investigated for Notch homolog 1, translocation-associated (Drosophila) (NOTCH1) c.7544-7545delCT, recombinant splicing factor 3B subunit 1 (SF3B1) c.2098A>G, mouse double minute 2 homolog (MDM2) 40-bp insertion/deletion and myeloid differentiation primary response 88 (MYD88) L265P mutations by using allele specific-polymerase chain reaction (AS-PCR), a designed AS-PCR, PCR and PCR-restriction fragment length polymorphism methods, respectively. The presence of NOTCH1 and SF3B1 mutations were confirmed by genomic DNA sequencing. The NOTCH1 mutation was detected in 10% of patients and not detected in the control group. A higher frequency of NOTCH1 mutation was detected in patients with stage III CLL (62.5%) compared with stages 0-II CLL (37.5%) (odds ratio, 4.69-fold; 95% confidence interval, 1.0-21.9; P=0.049). The SF3B1 mutation was observed in 12% of the patients compared with 1.9% of the controls (P=0.012). The presence of MDM2 polymorphism was not associated with the risk or the stage of the disease. In addition, the MYD88 L265P mutation was not detected in the patients or the controls. The current study established the frequency of NOTCH1, SF3B1, MDM2 and MYD88 mutations in patients with CLL from the Kurdish population of Western Iran. In summary, a high frequency of NOTCH1 and SF3B1 mutations were identified in patients with CLL compared with healthy individuals, and the NOTCH1 mutation was associated with a high stage of the disease.

Preclinical Evaluation of Bispecific Adaptor Molecule Controlled Folate Receptor CAR-T Cell Therapy With Special Focus on Pediatric Malignancies

Chimeric antigen receptor (CAR)-T cell therapy has transformed pediatric oncology by producing high remission rates and potent effects in CD19+ B-cell malignancies. This scenario is ideal as CD19 expression is homogeneous and human blood provides a favorable environment for CAR-T cells to thrive and destroy cancer cells (along with normal B cells). Yet, CAR-T cell therapies for solid tumors remain challenged by fewer tumor targets and poor CAR-T cell performances in a hostile tumor microenvironment. For acute myeloid leukemia and childhood solid tumors such as osteosarcoma, the primary treatment is systemic chemotherapy that often falls short of expectation especially for relapsed and refractory conditions. We aim to develop a CAR-T adaptor molecule (CAM)-based therapy that uses a bispecific small-molecule ligand EC17, fluorescein isothiocyanate (FITC) conjugated with folic acid, to redirect FITC-specific CAR-T cells against folate receptor (FR)-positive tumors. As previously confirmed in rodents as well as in human clinical studies, EC17 penetrates solid tumors within minutes and is retained due to high affinity for the FR, whereas unbound EC17 rapidly clears from the blood and from receptor-negative tissues. When combined with a rationally designed CAR construct, EC17 CAM was shown to trigger CAR-modified T cell activation and cytolytic activity with a low FR threshold against tumor targets. However, maximal cytolytic potential correlated with (i) functional FR levels (in a semi-log fashion), (ii) the amount of effector cells present, and (iii) tumors' natural sensitivity to T cell mediated killing. In tumor-bearing mice, administration of EC17 CAM was the key to drive CAR-T cell activation, proliferation, and persistence against FR+ pediatric hematologic and solid tumors. In our modeling systems, cytokine release syndrome (CRS) was induced under specific conditions, but the risk of severe CRS could be easily mitigated or prevented by applying intermittent dosing and/or dose-titration strategies for the EC17 CAM. Our approach offers the flexibility of antigen control, prevents T cell exhaustion, and provides additional safety mechanisms including rapid reversal of severe CRS with intravenous sodium fluorescein. In this paper, we summarize the translational aspects of our technology in support of clinical development.

Expression and Activity of Matrix Metalloproteinases in Leukemia

Matrix metalloproteinases (MMPs) are responsible for the degradation of extracellular matrix components and hence play a crucial role in physiological and pathologic processes. The imbalance between the expression of MMPs and their inhibitors can be effective in leukemic cell processes such as migration, angiogenesis, survival, and apoptosis, playing a key role in the progression and prognosis of leukemia. In this review, we discuss the potential involvement of MMPs and their inhibitors in the pathogenesis and progression of leukemia by examining their role in the prognosis of leukemia. Inducing leukemic cell growth, migration, invasiveness, and angiogenesis are the main roles of MMPs in leukemia progression mediated by their degradative activity. Given the important role of MMPs in leukemia progression, further clinical trials are needed to confirm the link between MMPs' expressions and leukemia prognosis. It is hoped to use MMPs as therapeutic targets to improve patients' health by recognizing the prognostic value of MMPs in leukemia and their effect on the progression of these malignancies and their response to treatment.

Abnormal microRNA expression in the course of hematological malignancies

Research on the carcinogenesis process is currently focused primarily on understanding its genetic basis and molecular abnormalities that may be predictive factors and therapeutic targets. It was clearly confirmed recently that microRNAs are involved in the mechanisms of leukocyte development, differentiation, and apoptosis, as well as in the pathogenesis of proliferative diseases of the hematopoietic system. Currently, research strategies allow determination of the deregulation of microRNA profiles in relation to other cytogenetic aberrations, as well as prognostic factors and primary end points. The problem of the possibility of their use as therapeutic targets is also increasingly discussed. In this article, we analyze literature data on abnormalities in microRNA expression in proliferative diseases of the hematopoietic system in the context of classic cytogenetic and molecular aberrations.

Untreated chronic lymphocytic leukemia in Lebanese patients: an observational study using standard karyotyping and FISH

AIM

We aimed to understand the biology of chronic lymphocytic leukemia (CLL) patients in Lebanon.

MATERIALS & METHODS

We applied conventional cytogenetic and FISH studies on Lebanese patients diagnosed with CLL and undergoing a watch and wait approach.

RESULTS

Our study disclosed 53.6% of patients with aberrant karyotypes among which 26.7% were complex karyotypes. Genetic aberrations included del(13q14) 46.4%, 14q32 translocation in 25%, trisomy 12 in 14.3%, del(17p13) and del(11q22) in 7.1% each. The deletion of 6q21/6q23 was not found in any of our patients.

CONCLUSION

The higher prevalence of del(13q14) as a sole abnormality could be the primary event in inducing CLL. The del(17p13) and del(11q22) followed as potential drivers for progression in CLL patients with a watch and wait approach.

Advances in chronic lymphocytic leukemia pharmacotherapy

Chronic lymphocytic leukemia (CLL) is a lymphoproliferative disease that affects B lymphocytes in most cases. Leukemic lymphocytes have prolonged longevity, defined by resistance to apoptosis. These cells can accumulate in peripheral blood, bone marrow, and solid lymphoid organs. CLL may be indolent or aggressive and has a range of prognostic factors such as expression of CD38 and ZAP-70, immunophenotypic and cytogenetic changes, imbalanced apoptosis proteins, and others. Although CLL has a low mortality rate, this disease is generally not considered curable until today. CLL treatment involves alkylating agents and glucocorticoids, purine analogs, monoclonal antibody therapies, and bone marrow transplantation. In recent decades, new drugs have appeared focusing on new targets and specific molecules, such as the BCR receptor, Bruton's tyrosine kinase, phosphatidylinositol 3-kinase, spleen tyrosine kinase, apoptosis proteins and microRNAs. The most appropriate treatment for CLL is one that involves in its protocol a combination of drugs according to the prognostic factors presented by each patient. In this sense, treatment individualization is essential. This article examines standard treatments for CLL and explores new treatments and potential new targets, as well as schematic protocols to understand where we are, how the treatment has evolved, and the advantages and disadvantages of new targets for CLL therapy.

Significance of Inactivated Genes in Leukemia: Pathogenesis and Prognosis

Epigenetic and genetic alterations are two mechanisms participating in leukemia, which can inactivate genes involved in leukemia pathogenesis or progression. The purpose of this review was to introduce various inactivated genes and evaluate their possible role in leukemia pathogenesis and prognosis. By searching the mesh words "Gene, Silencing AND Leukemia" in PubMed website, relevant English articles dealt with human subjects as of 2000 were included in this study. Gene inactivation in leukemia is largely mediated by promoter's hypermethylation of gene involving in cellular functions such as cell cycle, apoptosis, and gene transcription. Inactivated genes, such as ASPP1, TP53, IKZF1 and P15, may correlate with poor prognosis in acute lymphoid leukemia (ALL), chronic lymphoid leukemia (CLL), chronic myelogenous leukemia (CML) and acute myeloid leukemia (AML), respectively. Gene inactivation may play a considerable role in leukemia pathogenesis and prognosis, which can be considered as complementary diagnostic tests to differentiate different leukemia types, determine leukemia prognosis, and also detect response to therapy. In general, this review showed some genes inactivated only in leukemia (with differences between B-ALL, T-ALL, CLL, AML and CML). These differences could be of interest as an additional tool to better categorize leukemia types. Furthermore; based on inactivated genes, a diverse classification of Leukemias could represent a powerful method to address a targeted therapy of the patients, in order to minimize side effects of conventional therapies and to enhance new drug strategies.

T-cell leukemia/lymphoma-1A predicts the clinical outcome for patients with stage II/III colorectal cancer

T-cell leukemia/lymphoma-1A (TCL1A) as a stem cell marker is abundantly expressed in embryonic stem cells and has been identified as an oncogene in various hematological malignancies such as chronic lymphocytic leukemia and B-cell lymphoma. However, with regard to its role in solid tumors, few studies are available and less are for colorectal cancer (CRC). In this study, we aim to investigate the expression and clinical significance of TCL1A in a cohort of 278 stage II/III CRC patients. As a result, we find TCL1A expression is higher in CRC tissues than that in adjacent normal tissues, and significantly correlated with tumor differentiation, TNM stage and Ki-67 positive rate. The prognostic analysis suggests that TCL1A expression is an independent factor affecting CRC-specific and disease-free survival of these patients. Furthermore, we find stage II/III patients with high TCL1A expression have a significantly higher rate of postoperative local recurrence and metastasis than those with low TCL1A expression. Finally, through subgroup analysis, we find TCL1A expression can stratify the outcome of stage II/III patients who received standard adjuvant chemotherapy. Taken together, our findings suggest TCL1A is not only a useful biomarker for prognostic evaluation in stage II/III CRC patients, but also a promising therapeutic target for improving their clinical outcome.

Plasma matrix metalloprotease 9 correlates with blood lymphocytosis, leukemic cell invasiveness, and prognosis in B-cell chronic lymphocytic leukemia

The complex biology underlying chronic lymphocytic leukemia cell migration and tissue invasiveness is not yet completely understood and might provide novel predictive markers and therapeutic targets. A total of 36 patients out of treatment from at least 3 months were enrolled and followed up for a median period of 44.2 months (range: 4.4–99.2). Matrix metalloprotease 9 and tissue inhibitor of metalloproteases 1 plasma levels and production/release from lymphoid cells were measured by zymography and enzyme-linked immunosorbent assay (ELISA) analysis. Malignant and normal lymphocyte mobility and matrix-degradation capability were studied using a Boyden chamber system, with and without autologous plasma. Free matrix metalloprotease 9 plasma levels were related with blood lymphocytosis, especially in more advanced stages (p = 0.003), and higher concentrations were associated with an increased disease progression risk (hazard ratio = 9.0, 95% confidence interval = 1.5–13.8). Leukemic cells expressed and secreted very little matrix metalloprotease 9. On the contrary, normal lymphocytes derived from the same leukemic patients showed matrix metalloprotease 9 intracellular levels that were lower in subjects with higher blood lymphocytosis (p = 0.024) and more advanced stages (p = 0.03); the released quantities were inversely associated with matrix metalloprotease 9 plasma concentrations (p = 0.035). Leukemic cells had a reduced spontaneous mobility and matrix-degradation capability that were stimulated by autologous plasma (p = 0.001) and normal lymphocytes (p = 0.005), respectively. Matrix metalloprotease 9 affected cell invasiveness depending on concentration and disease stage. In conclusion, chronic lymphocytic leukemia cells have a reduced mobility, matrix-degradation capability, and matrix metalloprotease 9 production compared to their own autologous normal lymphocytes. They are exposed to matrix metalloprotease 9 of prevalently systemic origin whose higher levels are associated with both leukemic and normal lymphocyte accumulation in the peripheral blood and have a negative prognostic value.

Novel strategies for targeting leukemia stem cells: sounding the death knell for blood cancer

BACKGROUND

Cancer stem cells (CSCs), also known as tumor-initiating cells (TICs), are characterized by high self-renewal and multi-lineage differentiation capacities. CSCs are thought to play indispensable roles in the initiation, progression and metastasis of many types of cancer. Leukemias are thought to be initiated and maintained by a specific sub-type of CSC, the leukemia stem cell (LSC). An important feature of LSCs is their resistance to standard therapy, which may lead to relapse. Increasing efforts are aimed at developing novel therapeutic strategies that selectively target LSCs, while sparing their normal counterparts and, thus, minimizing adverse treatment-associated side-effects. These LSC targeting therapies aim to eradicate LSCs through affecting mechanisms that control their survival, self-renewal, differentiation, proliferation and cell cycle progression. Some LSC targeting therapies have already been proven successful in pre-clinical studies and they are now being tested in clinical studies, mainly in combination with conventional treatment regimens.

CONCLUSIONS

A growing body of evidence indicates that the selective targeting of LSCs represents a promising approach to improve disease outcome. Beyond doubt, the CSC hypothesis has added a new dimension to the area of anticancer research, thereby paving the way for shaping a new trend in cancer therapy.

Diagnosis of chronic lymphoproliferative disorders by flow cytometry using four-color combinations for immunophenotyping: A proposal of the brazilian group of flow cytometry (GBCFLUX)

BACKGROUND

Multiparametric flow cytometry (MFC) is a powerful tool for the diagnosis of hematological malignancies and has been useful for the classification of chronic lymphoproliferative disorders (CLPD) according to the WHO criteria. Following the purposes of the Brazilian Group of Flow Cytometry (GBCFLUX), the aim of this report was to standardize the minimum requirements to achieve an accurate diagnosis in CLPDs, considering the different economic possibilities of the laboratories in our country. Most laboratories in Brazil work with 4-fluorescence flow cytometers, which is why the GBCFLUX CLPD Committee has proposed 4-color monoclonal antibody (MoAb) panels.

METHODS/RESULTS

Panels for screening and diagnosis in B, T and NK lymphoproliferative disorders were developed based on the normal differentiation pathways of these cells and the most frequent phenotypic aberrations. Important markers for prognosis and for minimal residual disease (MRD) evaluation were also included. The MoAb panels presented here were designed based on the diagnostic expertise of the participating laboratories and an extensive literature review.

CONCLUSION

The 4-color panels presented to aid in the diagnosis of lymphoproliferative neoplasms by GBCFLUX aim to provide clinical laboratories with a systematic, step-wise, cost-effective, and reproducible approach to obtain an accurate immunophenotypic diagnosis of the most frequent of these disorders. © 2016 International Clinical Cytometry Society.

Mesenchymal stem cells as a double-edged sword in suppression or progression of solid tumor cells

Tumor cells are able to attract mesenchymal stem cells (MSCs) to primary tumor site. On the other hand, MSCs secrete various factors to attract tumor cells towards BM. In this review, in addition to assessment of MSCs function at tumor sites and their impact on growth and metastasis of tumor cells, the importance of MSC in attraction of malignant cells to BM and their involvement in drug resistance of tumor cells have also been studied. Relevant literature was identified by a PubMed search (2000-2015) of English-language literature using the terms mesenchymal stem cells, cancer cell, metastasis, and tumor microenvironment. MSCs migrate towards tumor microenvironment and are involved in both pro-tumorigenic and antitumorigenic functions. The dual function of MSCs at tumor sites is dependent upon a variety of factors, including the type and origin of MSCs, the cancer cell line under study, in vivo or in vitro conditions, the factors secreted by MSCs and interactions between MSCs, host immune cells and cancer cells. Therefore, MSCs can be regarded both as friends and enemies of cancer cells. Although the role of a number of pathways, including IL-6/STAT3 pathway, has been indicated in controlling the interaction between MSCs and tumor cells, other mechanisms by which MSCs can control the tumor cells are not clear yet. A better understanding of these mechanisms through further studies can determine the exact role of MSCs in cancer progression and identify them as important therapeutic agents or targets.

Direct Coombs Test Positivity in B-Chronic Lymphoid Leukemia: a Marker of Advanced Clinical Disease

BACKGROUND

Chronic lymphoid leukemia (CLL) is a malignant hematopoietic disorder, the most common of all adult leukemias with a distinctive immunophenotype. It is well established that CLL patients can have autoimmune complications, amongst them autoimmune hemolytic anemia as the most frequent. This study was carried out to determine the frequency of direct Coombs Test positivity in CLL patients and its possible correlation with Rai staging, hematological parameters and biochemical markers.

MATERIALS AND METHODS

This descriptive cross sectional study was carried at Liaquat National Hospital from January 2011 to June 2013. Sixty untreated patients with B- chronic lymphoid leukemia were enrolled. Complete blood count, direct Coombs test, serum urea, creatinine, uric acid and LDH levels were determined. Data were compiled and analyzed using SPSS version 21.

RESULTS

Out of 60 patients, 42(70%) were males and 18(30%) were females. Mean age was 59±9.2 years. Male to female ratio was 2.1: 1. The frequency of direct antiglobulin test (DAT) positivity was found to be 23.3%. The monospecific IgG was positive in 11 patients (18.3%); C3d positivity was evident in 1 patient (1.6%) and 2 patients (3.3%) had dual IgG and C3d positivity. The mean hemoglobin was 10.8±2.4gm/ dl. Significantly low mean hemoglobin of 8.3±3.0 gm/dl was seen in Coombs positive patients compared with negative patients having a mean hemoglobin level of 11.7±1.6 gm/dl (P<0.001). DAT positivity also demonstrated a positive association with advanced Rai stage III disease (P<0.01). No associations were noted with age, gender and biochemical markers.

CONCLUSIONS

Direct Coombs test positivity in CLL in our patients, unlike in Western studies, appears relatively high, indicating significant autoimmune hemolytic anemia and advanced Rai stage in our setting. DAT positivity can be considered as a surrogative marker for advanced clinical disease.

Signaling and molecular basis of bone marrow niche angiogenesis in leukemia

Angiogenesis, the process of blood vessel formation, is necessary for tissue survival in normal and pathologic conditions. Increased angiogenesis in BM niche is correlated with leukemia progression and resistance to treatment. Angiogenesis can interfere with disease progression and several angiogenic (such as vascular growth factors) as well as anti-angiogenic factors (i.e. angiostatin) can affect angiogenesis. Furthermore, miRs can affect the angiogenic process by inhibiting angiogenesis or increasing the expression of growth factors. Given the importance of angiogenesis in BM for maintenance of leukemic clones, recognition of angiogenic and anti-angiogenic factors and miRs as well as drug resistance mechanisms of leukemic blasts can improve the therapeutic strategies. We highlight the changes in angiogenic balance within the BM niche in different leukemia types. Moreover, we explored the pathways leading to drug resistance in relation to angiogenesis and attempted to assign interesting candidates for future research.