[Show abstract][Hide abstract] ABSTRACT: Molecular and genetic evidence suggests that DNA repair pathways may contribute to lymphoma susceptibility. Several studies have examined the association of DNA repair genes with lymphoma risk, but the findings from these reports have been inconsistent. Here we provide the results of a focused analysis of genetic variation in DNA repair genes and their association with the risk of non-Hodgkin's lymphoma (NHL). With a population of 1,297 NHL cases and 1,946 controls, we have performed a two-stage case/control association analysis of 446 single nucleotide polymorphisms (SNPs) tagging the genetic variation in 81 DNA repair genes. We found the most significant association with NHL risk in the ATM locus for rs227060 (OR = 1.27, 95% CI: 1.13-1.43, p = 6.77×10-5), which remained significant after adjustment for multiple testing. In a subtype-specific analysis, associations were also observed for the ATM locus among both diffuse large B-cell lymphomas (DLBCL) and small lymphocytic lymphomas (SLL), however there was no association observed among follicular lymphomas (FL). In addition, our study provides suggestive evidence of an interaction between SNPs in MRE11A and NBS1 associated with NHL risk (OR = 0.51, 95% CI: 0.34-0.77, p = 0.0002). Finally, an imputation analysis using the 1,000 Genomes Project data combined with a functional prediction analysis revealed the presence of biologically relevant variants that correlate with the observed association signals. While the findings generated here warrant independent validation, the results of our large study suggest that ATM may be a novel locus associated with the risk of multiple subtypes of NHL.
[Show abstract][Hide abstract] ABSTRACT: Livin is a member of the Inhibitor of Apoptosis (IAP) protein family that inhibits apoptosis triggered by a variety of stimuli. We previously demonstrated that while Livin inhibits caspase activity, caspases can cleave Livin to produce a truncated protein, tLivin and that this newly formed tLivin paradoxically induces cell death. However to date, the mechanism of tLivin-induced cell death is not fully understood. In this study, we set out to characterize the form of cell death mediated by tLivin. Here we demonstrate that, unlike most death-promoting proteins, tLivin is a flexible inducer of cell death capable of promoting necrosis or apoptosis in different cell lines. The unusual flexibility of tLivin is displayed by its ability to activate an alternative form of cell death when apoptosis is inhibited. Thus, tLivin can promote more than one form of cell death in the same cell type. Interestingly, in cells where tLivin induces necrosis, deletion of the caspase binding BIR domain results in tLivin-induced apoptosis, suggesting the BIR domain can potentially hamper the ability of tLivin to induce apoptosis. We further elucidate that tLivin activates the JNK pathway and both tLivin-induced apoptosis and necrosis are partially mediated by JNK activity. Acquired resistance to apoptosis, common in many tumors, impinges on the efficiency of conventional anti-cancer agents that function primarily by inducing apoptosis. The ability of tLivin to induce death of apoptosis-compromised cells makes it an attractive candidate for targeted cancer therapy.
[Show abstract][Hide abstract] ABSTRACT: Abstract The optimal tyrosine kinase inhibitor for any individual patient with chronic myeloid leukemia (CML) is not predictable. Pharmacogenetic parameters and trough levels of imatinib (IM) have each been independently correlated with response. We therefore studied hOCT1 and MDR1 single nucleotide polymorphisms (SNPs) and correlated these with IM levels and MMR (3 log reduction) in 84 CML patients, the first such study performed in Caucasians. We studied MDR1 G2677T and C3435T and for hOCT1, C480G and A1222G. IM levels significantly varied with dose (< or >400mg/day) (p=0.038) and were significantly lower in 20 patients who lost MMR (p=0.042). Adjusting for dose, trough IM levels were not significantly correlated with SNPs. Patients with MDR1 3435 TT had significantly longer times to MMR compared to CC/CT genotypes (p=0.047). Genotypes did not predict treatment failure when controlling for IM levels. We conclude that IM levels, but not the SNPs studied here, determine IM failure.
Full-text · Article · Feb 2014 · Leukemia & lymphoma
[Show abstract][Hide abstract] ABSTRACT: PML-RARA and AML1-ETO are important oncogenic fusion proteins that play a central role in transformation to acute myeloid leukemia (AML). Whether these fusion proteins render the tumor cells with immune evasion properties is unknown. Here we show that both oncogenic proteins specifically downregulate the expression of CD48, a ligand of the natural killer (NK) cell activating receptor 2B4, thereby leading to decreased killing by NK cells. We demonstrate that this process is histone deacetylase (HDAC)-dependent, that it is mediated through the downregulation of CD48 mRNA and that treatment with HDAC inhibitors (HDACi) restores the expression of CD48. Furthermore, by using chromatin immuoprecepitation (ChIP) experiments we show that AML1-ETO directly interacts with CD48. Finally, we show that AML patients carrying these specific translocations have low expression of CD48.
[Show abstract][Hide abstract] ABSTRACT: Livin is a member of the inhibitor of apoptosis proteins (IAP) family of intracellular antiapoptotic proteins that act by binding and inhibiting caspases. Upon strong apoptotic stimuli, it is then specifically cleaved by caspases to produce a truncated protein (tLivin) with a paradoxical proapoptotic activity. Intriguingly, we have detected robust protein levels of Livin in normal mature bone marrow megakaryocyte (MK) and platelets. To evaluate the potential role of Livin in thrombopoiesis, we used the human BCR-ABL+ cell line, LAMA-84, and cord blood CD34+ cells to induce differentiation toward MKs. Upon differentiation, induced by phorbol myristate acetate and concurrent with increase in Livin protein expression, LAMA-84 cells formed functional platelet-like particles. Livin overexpression in CD34+ progenitor cells induced higher endoreplication in the MKs generated. Furthermore, overexpression of Livin increased the ability of both primary MKs and differentiated LAMA-84 cells to produce functional platelets. In the differentiated LAMA-84 cells, we observed accumulation of proapoptotic tLivin concomitant with increased caspase-3 activity. Downregulation of Livin with small interfering RNA in both leukemic and primary MK cells decreased their ability to produce functional platelets. We suggest that Livin has a role in thrombopoiesis by regulating the apoptotic and antiapoptotic balance in MK endoreplication and platelet production.
Full-text · Article · Nov 2013 · Cell Death & Disease
[Show abstract][Hide abstract] ABSTRACT: Loss of nerve growth factor-mediated neuronal survival has
recently been proposed as a candidate mechanism underlying
bortezomib-induced peripheral neuropathy (BIPN) (Broyl
et al, 2010). However the literature does not reveal any data
from patients that can support this hypothesis. Brain-derived
neurotrophic factor (BDNF) is a neuronal growth factor that
is crucial for neuronal survival and repair (Hofer & Barde,
1988). We report on alterations in BDNF peripheral blood
levels and the development of BIPN in patients with multiple
Full-text · Article · Oct 2013 · British Journal of Haematology
[Show abstract][Hide abstract] ABSTRACT: Immune hemolytic anemia (IHA) may complicate the course of chronic lymphocytic leukemia (CLL), especially in patients with advanced disease, and as a complication of treatment with chlorambucil or fludarabine. Bendamustine, a novel agent with both alkylating and purine-analog properties, was approved in the USA for use in CLL in 2008. Since then, clinical data on its adverse events are accumulating. IHA related to bendamustine was seldom described and is thus reported and reviewed.
We assessed five cases of CLL patients complicated by IHA, out of 31 treated with bendamustine for a relapse of their disease. Also reviewed are previous case reports in the literature.
Bendamustine-related IHA is more common than suspected (16 %). No such cases were found in non-CLL patients. Personal history of fludarabine-triggered AIHA may be a risk factor for this complication (recorded in 4/5 patients, 80 %). The mechanism is thought to be related to the loss of T cell regulatory control as described for other agents. Physicians using bendamustine for the treatment for CLL should be aware of this complication.
Full-text · Article · Aug 2013 · Cancer Chemotherapy and Pharmacology
[Show abstract][Hide abstract] ABSTRACT: The genetics of lymphoma susceptibility reflect the marked heterogeneity of diseases that comprise this broad phenotype. However, multiple subtypes of lymphoma are observed in some families, suggesting shared pathways of genetic predisposition to these pathologically distinct entities. Using a two-stage GWAS, we tested 530,583 SNPs in 944 cases of lymphoma, including 282 familial cases, and 4,044 public shared controls, followed by genotyping of 50 SNPs in 1,245 cases and 2,596 controls. A novel region on 11q12.1 showed association with combined lymphoma (LYM) subtypes. SNPs in this region included rs12289961 near LPXN, (P(LYM) = 3.89×10(-8), OR = 1.29) and rs948562 (P(LYM) = 5.85×10(-7), OR = 1.29). A SNP in a novel non-HLA region on 6p23 (rs707824, P(NHL) = 5.72×10(-7)) was suggestive of an association conferring susceptibility to lymphoma. Four SNPs, all in a previously reported HLA region, 6p21.32, showed genome-wide significant associations with follicular lymphoma. The most significant association with follicular lymphoma was for rs4530903 (P(FL) = 2.69×10(-12), OR = 1.93). Three novel SNPs near the HLA locus, rs9268853, rs2647046, and rs2621416, demonstrated additional variation contributing toward genetic susceptibility to FL associated with this region. Genes implicated by GWAS were also found to be cis-eQTLs in lymphoblastoid cell lines; candidate genes in these regions have been implicated in hematopoiesis and immune function. These results, showing novel susceptibility regions and allelic heterogeneity, point to the existence of pathways of susceptibility to both shared as well as specific subtypes of lymphoid malignancy.
[Show abstract][Hide abstract] ABSTRACT: Advanced melanoma cells, characterized by resistance to chemotherapy, have been shown to be highly sensitive to oncolysis by Newcastle disease virus (NDV). In the present study, we investigated the capacity of NDV to specifically infect and spread into solid tissues of human melanoma and lung carcinoma, in vivo and ex vivo. For this purpose a new model of SCID-beige mice implanted with human melanoma was developed. Surprisingly, the replication competent NDV-MTH and the attenuated, single-cycle replication NDV-HUJ strains, demonstrated a similar oncolytic activity in the melanoma-implanted mice. Further, ex vivo analysis, using organ cultures derived from the melanoma tissues indicated a limited spread of the two NDV strains in the tissue. Extracellular matrix (ECM) molecules, notably heparin sulfate and collagen, were found to limit viral spread in the tissue. This observation was validated with yet another solid tumour of human lung carcinoma. Taken together, the results indicate that the ECM acts as a barrier to virus spread within solid tumour tissues and that this restriction must be overcome to achieve effective oncolysis with NDV.
Full-text · Article · May 2012 · Journal of General Virology
[Show abstract][Hide abstract] ABSTRACT: The inhibitor of apoptosis protein (IAP) livin is frequently overexpressed in melanoma. Livin binds caspases and thereby inhibits apoptosis. We found that caspases cleave livin to produce a truncated form with a paradoxical proapoptotic activity.
We assessed the correlation of livin expression with survival among 114 melanoma patients treated with an autologous melanoma vaccine. In 52 patients, resection resulted in no evidence of disease (NED) and 62 remained with active disease (WAD). Protein levels were assessed using Western blot.
We found livin protein expression in 44/114 samples (38.4%). Median overall survival was 1.4 years in NED patients with high levels of livin protein, 8.4 years in those with low-intermediate levels and not reached in patients who did not express livin (p = 0.025). The corresponding overall survival was 2.3 years among WAD patients with high levels of livin protein, 11.3 years in those with low-intermediate levels and, paradoxically, only 4.0 years in patients who did not express livin (p = 0.012).
Livin protein expression may play a role in the progression of melanoma and correlates with survival. A high level of the protein is associated with a poor prognosis. However, in WAD patients low to intermediate level of livin, rather than absence of the protein, is associated with a favorable prognosis. This is probably due to the paradoxical proapoptotic activity of this important regulator of apoptosis.
[Show abstract][Hide abstract] ABSTRACT: In this retrospective study, we aim to analyze the characteristics, treatments, and overall survival of all patients presenting with isolated myeloid sarcoma (MS) or MS with concomitant acute myeloid leukemia (AML) compared with all patients with AML, treated during the same period. We identified patients with AML with or without MS at diagnosis, presenting to our medical center between the years 1990 and 2005. There was no statistically significant difference between the groups regarding gender, age, cytogenetic risk groups, rate of complete remission, number of cycles of chemotherapy needed to achieve complete remission, and rate of first relapse. The time to death in the MS group was not significantly different (p = 0.60) from the AML group, and radiotherapy did not affect the median time to death. Transplantation prolonged survival in both groups (p = 0.018 and p < 0.0001, respectively). Patients with MS at diagnosis might benefit from upfront aggressive treatment with hematopoietic stem cell transplantation.
No preview · Article · Mar 2012 · Hematological Oncology
[Show abstract][Hide abstract] ABSTRACT: The JAK2 V617F mutation is responsible for the constitutive activation of the erythropoietin receptor signaling pathway in most cases of polycythemia vera (PV). The mutation has also been described in healthy people. As smoking may result in secondary polycythemia, the goal of this trial was to examine the effect of smoking on the prevalence of the JAK2 mutation and its correlation to erythrocytosis. The study was case-control. Hospitalized smokers (n = 81) and nonsmokers (n = 61) were recruited. Serum was drawn for complete blood count, erythropoietin, ferritin and venous blood gases. JAK2 mutation was analyzed by highly sensitive allele-specific Quantitative Real Time PCR. The JAK2 mutation was found in 29/81 (35.8%) of smokers in comparison to only 9/61 (14.8%) of the control group (P = 0.007). The frequency of the mutation among smokers who were positive for the JAK2 mutation had a mean of 6.78 × 10(-4) ± 1.08 × 10(-3) vs. 1.51 × 10(-4) ± 2.04 × 10(-4) among nonsmokers (P = 0.027). Both frequencies are much lower than those found in PV. There was a medium correlation between older age and mutation frequency in nonsmokers (r= 0.67, P = 0.043). Hematocrit was higher in smokers (47.8 ± 6 vs. 41.7 ± 4.7, P < 0.0001), but no correlation was found to JAK2 mutation. In a cohort of hospitalized smokers and nonsmokers, JAK2 mutation was more prevalent and found in higher frequencies among smokers than nonsmokers. We suggest that accelerated erythropoiesis renders the cells susceptible to JAK2 mutation.
Preview · Article · Jan 2012 · American Journal of Hematology
[Show abstract][Hide abstract] ABSTRACT: Treatment of hairy cell leukemia (HCL) with cladribine induces durable remissions. Common toxicities are myelosuppression and immunosuppression with low counts of CD4 + T cells. Skin rash (SR) is seldom described. We collected clinical and laboratory data of 35 patients with HCL treated in Hadassah between January 1999 and February 2010, in order to evaluate the frequency and characteristics of SR after treatment with cladribine. We found a high frequency of SR in our group of patients (18/35 patients, 51%), mostly related to febrile neutropenia and concomitant treatment with penicillins/trimethoprim-sulfamethoxazole (TMP-SMZ). The lymphocyte count was low in all patients with SR. We conclude that patients with HCL treated with cladribine have an increased rate of drug hypersensitivity, possibly due to T-cell imbalance induced by cladribine. Since TMP-SMZ and penicillins are related to SR in most cases and are important in the management of patients with HCL, a desensitization protocol should be considered. Rechallenge may be safe after immune reconstitution.
No preview · Article · Dec 2011 · Leukemia & lymphoma
[Show abstract][Hide abstract] ABSTRACT: We present a case of a 52-year-old male who was evaluated due to anorexia, persistent diarrhea, weight loss, and liver enzyme elevations, with no hematologic laboratory abnormalities. Imaging modalities revealed several tissue lesions involving the pancreas, the right kidney, and an axillary lymph node. Diagnosis of Castleman disease was reached only due to the tissue obtained from the lymph node. Chemotherapy and immunosuppression led to a short remission. The patient underwent autologous stem cell transplantation, and has since been in remission. This case demonstrates the cryptogenic and chameleon-like nature of Castleman disease. Challenges in treating Castleman disease patients reflect current limitations and the need for a greater understanding of disease pathogenesis.
No preview · Article · Mar 2011 · International journal of hematology
[Show abstract][Hide abstract] ABSTRACT: A somatic point mutation in the JAK2 gene results in a constitutive activation of the JAK2 kinase in the erythropoietin (epo) signal transduction pathway. The mutation was found in Polycythemia Vera (PV) patients (>95%) as well as in other myeloproliferative disorders (MPD). In MPD the mutation was shown to occur in pluripotential hematopoietic stem cells and to be present in all blood cell lineages. We analyzed DNA of blood donors for the JAK2V617F mutation by allele specific Real Time PCR. The mutation was detected in 9% of 114 samples with a very low mutation frequency of < 0.002% per sample (mutant/wild-type DNA allelic ratio) in comparison to frequency of 50-100% in PV.
We speculated that accelerated erythropoiesis with increased erythroid differentiation will result in higher mutation rate. We therefore studied the presence of V617F mutation in two conditions associated with increased erythropoiesis, thalassemia and smoking.
In beta-thalassemia major patients, the mutation was found in 22.2% (12/54), a significant 2.4-fold increase in mutation incidence compared to healthy individuals (p=0.016). The mutation frequency was 0.035% per positive sample.
The V617F mutation was studied in a case – control study of hospitalized smokers (n=81) and non-smokers (n=61). Smoking was defined as 10 or more cigarettes per day, everyday of the week, for at least 10 consecutive years. Smoking status was assessed by a questionnaire and validated with measurement of exhaled carbon monoxide. Smokers suffered more chronic lung disease than non-smokers (45.7% vs. 6.6%, respectively, p<0.0001) and had a higher hematocrit, RBC and WBC (47.8% vs. 41.7% p<0.0001, 5.2 vs. 4.4x1012 cells/liter, p<0.0001 and 9.4 vs. 7.6x109 cells/liter, p=0.003, respectively). In all subjects epo was within the normal range or higher. The proportion of subjects with higher than normal epo was similar in smokers and non-smokers.
The prevalence of the mutation was significantly higher among the smokers (36%) than among the controls (15%) (p= 0.005) The median V617F mutation frequency in smokers was 10 fold higher than in controls (0.032% and 0.0032% respectively; p=0.027).
Very low V617F mutation frequency in DNA of non-MPD blood donors led us to question whether in these non-MPD individuals V617F mutation occurs in stem sells as was shown for PV patients. We found that the mutation was more frequent in peripheral blood mononuclear cells than in CD34+ cells purified from these mononuclear cells. Following 3 weeks culturing of CD34+ cells with epo mutation frequency increased by 9-folds (range 6-14) in hemoglobin-containing normoblasts. We next grew individual erythroid colonies from 8 healthy donors in semi-solid culture in the presence of epo. Out of 201 single colonies analyzed 13% contained the JAK2V617F mutation in a very small proportion of the cells (< 0.02%). These results demonstrate that in non-MPD individuals V617F mutation arises in very low frequency during cell differentiation.
We established a cell line model to study the occurrence of JAK2V617F mutation during erythroid differentiation. Mouse erythroleukemia (MEL) cells were transfected with the 1kb fragment of human JAK2 gene containing exon 14 sub-cloned into a mammalian expression vector. MEL cells were stimulated to differentiate by hexamethylene bisacetamide and the frequency of sequence changes in the JAK2 exon 14 was investigated. We found that changes in the JAK2 exon 14 sequence occurred at late stages of differentiation.
We hypothesize that maintenance of DNA fidelity is down graded with cell differentiation, rendering the cells susceptible for mutations in general and in JAK2 in particular.
In summary, accelerated erythropoiesis results in increased V617F mutation frequency such as in beta-thalassemia major patients and in heavy smokers. We demonstrate that unlike in MPD where the JAK2V617F mutation occurs in pluripotential stem cells and expands extensively, in non-MPD individuals it arises at very low frequency during cell differentiation. These differences determine the lack of clinical significance of the JAK2V617F mutation in non-MPD individuals.
[Show abstract][Hide abstract] ABSTRACT: Neurolymphomatosis (NL) is a rare clinical entity. The International Primary CNS Lymphoma Collaborative Group retrospectively analyzed 50 patients assembled from 12 centers in 5 countries over a 16-year period. NL was related to non-Hodgkin lymphoma in 90% and to acute leukemia in 10%. It occurred as the initial manifestation of malignancy in 26% of cases. The affected neural structures included peripheral nerves (60%), spinal nerve roots (48%), cranial nerves (46%), and plexus (40%) with multiple site involvement in 58%. Imaging studies often suggested the diagnosis with 77% positive magnetic resonance imaging, and 84% (16 of 19) positive computed tomography-positron emission tomography studies. Cerebrospinal fluid cytology was positive in 40%, and nerve biopsy confirmed the diagnosis in 23 of 26 (88%). Treatment in 47 patients included systemic chemotherapy (70%), intra-cerebrospinal fluid chemotherapy (49%), and radiotherapy (34%). Response to treatment was observed in 46%. The median overall survival was 10 months, with 12- and 36-month survival proportions of 46% and 24%, respectively. NL is a challenging diagnosis, but contemporary imaging techniques frequently detect the relevant neural invasion. An aggressive multimodality therapy can prevent neurologic deterioration and is associated with a prolonged survival in a subset of patients.