Search

Background/Aims: The JAK2V617F mutation, which has been found in patients with myeloproliferative disorders (MPD), has not yet been evaluated in lymphoproliferative disor- ders by any adequately sensitive techniques. Methods: We investigated whether low levels of JAK2V617F are present in lymphoid neoplasms using a highly sensitive and highly specific amplification refractory mutation system PCR (ARMS-PCR) assay. Results: While 234 of 237 cases did not carry the JAK2V617F allele, it was identified in the bone marrow of 3 B cell lymphoma patients. The mutation was found to be neither associated with the lymphomas per se, nor with any signs, symptoms or laboratory findings of MPD. Moreover, JAK2V617F appeared subsequently in the peripheral blood of 2 of the 3 patients. Conclusion: These findings suggest that JAK2V617F arises in the bone marrow of individuals before clinical manifestation of any myeloid disorders. Presence of JAK2V617F in bone marrow might therefore increase the risk of future MPD development, just as monoclonal gammopathy of undetermined significance (MGUS) increases the risk of multiple myeloma. We term this phenomenon ‘JAK2V617F of undetermined significance’ (JMUS). Its clinical significance remains to be determined. To our knowledge, these findings represent the first identification of JAK2V617F in the bone marrow of patients without myeloid malignancies. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy associated with various combinations of gene mutations, epigenetic abnormalities, and chromosome rearrangement-related gene fusions. Despite the significant degree of heterogeneity in its pathogenesis, many gene fusions and point mutations are recurrent in AML and have been employed in risk stratification over the last several decades. Gene fusions have long been recognized for understanding tumorigenesis and their proven roles in clinical diagnosis and targeted therapies. Advances in DNA sequencing technologies and computational biology have contributed significantly to the detection of known fusion genes as well as for the discovery of novel ones. Several recurring gene fusions in AML have been linked to prognosis, treatment response, and disease progression. Here, we present a case with a long history of essential thrombocythemia and hallmark CALR mutation transforming to AML characterized by a previously unreported AKAP9::PDGFRA fusion gene. We propose mechanisms by which this fusion may contribute to the pathogenesis of AML and its potential as a molecular target for tyrosine kinase inhibitors. Journal: Leukemia Research Reports [ABSTRACT FROM AUTHOR]

Abstract: In a series of 105 patients with polycythemia vera, we retrospectively determined whether the JAK2 V617F mutation correlated with severity of disease phenotype. Higher JAK2 V617F allele burden correlated with more advanced myelofibrosis, greater splenomegaly, and higher white blood cell count, but not with age, gender, hematocrit level, or frequency of phlebotomy prior to cytoreductive therapy. Although a subgroup at increased risk for thrombosis was not clearly defined, there was a suggestion that frequency of thrombosis increased as the JAK2 V617F allele burden increased. The JAK2 V617F allele burden did not change significantly in treated patients with serial JAK2 analyses. [ABSTRACT FROM AUTHOR]

Summary: The Bcl-2-associated X protein (Bax) and Bcl-2-antagonist/killer (Bak) are essential regulators of lymphocyte apoptosis, but whether they play a role in viable T cell function remains unclear. Here, we report that T cells lacking both Bax and Bak display defects in antigen-specific proliferation because of Ca2+-signaling defects. Bax−/−, Bak−/− T cells displayed defective T cell receptor (TCR)- and inositol-1,4,5-trisphosphate (IP3)-dependent Ca2+ mobilization because of altered endoplasmic reticulum (ER) Ca2+ regulation that was reversed by Bax''s reintroduction. The ability of TCR-dependent Ca2+ signals to stimulate mitochondrial NADH production in excess of that utilized for ATP synthesis was dependent on Bax and Bak. Blunting of Ca2+-induced mitochondrial NADH elevation in the absence of Bax and Bak resulted in decreased reactive-oxygen-species production, which was required for T cell proliferation. Together, the data establish that Bax and Bak play an essential role in the control of T cell proliferation by modulating ER Ca2+ release. [Copyright &y& Elsevier]

Diffuse large B-cell lymphoma (DLBCL) is a heterogenous group of lymphoid malignancies. Based on gene expression profiling, it has been subdivided into germinal center (GC)-derived and activated B-cell (ABC) types. Advances in molecular methodologies have further refined the subclassification of DLBCL, based on recurrent genetic abnormalities. Here, we describe a distinct case of DLBCL that presented in leukemic form. DNA sequencing targeting 275 genes revealed pathogenically relevant mutations of CD79B , MyD88 , TP53 , TBL1XR1 , and PIM1 genes, indicating that this lymphoma would be best classified as MCD/C5 DLBCL, an ABC subtype. Despite an initial good clinical response to BTK inhibitor ibrutinib, anti-CD20 antibody rituxan, alkylating agent bendamustine, and hematopoietic stem-cell transplant, the lymphoma relapsed, accompanied by morphologic and molecular evidence of disease progression. Specifically, the recurrent tumor developed loss of TP53 heterozygosity (LOH) and additional chromosomal changes central to ABC DLBCL pathogenesis, such as PRDM1 loss. Acquired resistance to ibrutinib and rituxan was indicated by the emergence of BTK and FOXO1 mutations, respectively, as well as apparent activation of alternative cell-activation pathways, through copy-number alterations (CNAs), detected by high-resolution chromosomal microarrays. In vitro, studies of relapsed lymphoma cells confirmed resistance to standard BTK inhibitors but sensitivity to vecabrutinib, a noncovalent inhibitor active against both wild-type as well as mutated BTK. In summary, we provide in-depth molecular characterization of a de novo leukemic DLBCL and discuss mechanisms that may have contributed to the lymphoma establishment, progression, and development of drug resistance., (© 2023 Kim et al.; Published by Cold Spring Harbor Laboratory Press.)

In chronic lymphocytic leukemia (CLL), patients with unmutated immunoglobulin heavy chain variable region gene (UM-CLL) have worse outcomes than mutated CLL (M-CLL) following chemotherapy or chemoimmunotherapy. However, in the era of BCR-targeted therapies, the adverse prognostic impact of unmutated IGHV seems to be diminishing, and there are clinical datasets showing unexpected improved responses in UM-CLL. We investigated the biological differences of BTK activity between these subgroups and further compared the impact of ibrutinib on molecular and cellular behaviors. Immunoblotting analysis revealed that phosphorylated active BTK is significantly higher in UM-CLL. Moreover, UM-CLL, compared to M-CLL, displayed a much higher proliferative capacity that was correlated with higher phospho-BTK and greater sensitivity to ibrutinib. In addition, BTK depletion with siRNA led to a more prominent reduction in the proliferation of UM-CLL, suggesting that elevated BTK activity is responsible for increased cell proliferation. Further, cell signaling activity by multiple measurements was consistently higher in UM-CLL accompanied by a higher sensitivity to ibrutinib. These studies link UM-CLL to elevated BCR signaling, heightened BTK-dependent cell proliferation and increased sensitivity to ibrutinib. The prognostic significance of IGHV mutation should be reevaluated in the era of new therapies targeting BCR signaling.

Kaposi sarcoma herpesvirus/human herpesvirus-8 (KSHV/HHV-8) is etiologically related to the development of several human diseases, including Kaposi sarcoma, primary effusion lymphoma (PEL)/extra-cavitary (EC) PEL, multicentric Castleman disease (MCD), and large B-cell lymphoma arising in KSHV/HHV-8-associated multicentric Castleman disease. Although serologic studies can identify persons infected with this virus, molecular genetics, specifically PCR (polymerase chain reaction) and immunohistochemical techniques, are rapid, sensitive, and specific, and are able to more closely link KSHV/HHV-8 to a given disease process. As these KSHV/HHV-8-related diseases cause significant morbidity and mortality in affected individuals, the identification of the virus within lesional tissue will allow for more targeted therapy.

Recently, a point mutation in the JAK2 gene, JAK2 (V617F) , was discovered in several myeloid proliferative neoplasms including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Demonstration of the mutation and other similar mutations has now become one of the major criteria in the diagnosis of these neoplasms in the revised World Health Organization Classification of Tumors of Hematopoietic Tissues. In this chapter, we compared the advantages and disadvantages of five commonly used methods for the detection of JAK2 (V617F) . We explained, based on the current literature, why analytic sensitivity of the methodology is of particular importance for the detection of JAK2 (V617F) . A detailed laboratory procedure for the performance of an extensively optimized ARMS-PCR assay was presented. The assay shows distinct patterns for normal, mutant, and mixed genotypes. Diagnostically, it is highly sensitive, highly specific, and simple to perform with no need for any specialized equipment other than thermocyclers.

Background: Although reduction in the JAK2(V617F) allele burden (%V617F) has been suggested as a criterion for defining disease response to cytoreductive therapy in polycythemia vera, its value as a response monitor is unclear. The purpose of this study is to determine whether a reduction in %V617F in polycythemia vera is a prerequisite to achieving hematologic remission in response to cytoreductive therapy., Design and Methods: We compared the clinical and hematologic responses to change in %V617F (molecular response) in 73 patients with polycythemia vera treated with either interferon (rIFNα-2b: 28, Peg-rIFNα-2a: 18) or non-interferon drugs (n=27), which included hydroxyurea (n=8), imatinib (n=12), dasatinib (n=5), busulfan (n=1), and radioactive phosphorus (n=1). Hematologic response evaluation employed Polycythemia Vera Study Group criteria, and molecular response evaluation, European Leukemia Net criteria., Results: Of the 46 treated with interferon, 41 (89.1%) had a hematologic response, whereas only 7 (15.2%) had a partial molecular response. Of the 27 who received non-interferon treatments, 16 (59.3%) had a hematologic response, but only 2 (7.4%) had a molecular response. Median duration of follow up was 2.8 years. Statistical agreement between hematologic response and molecular response was poor in all treatment groups., Conclusions: Generally, hematologic response was not accompanied by molecular response. Therefore, a quantitative change in %V617F is not required for clinical response in patients with polycythemia vera.

Background & Aims: The peroxisome proliferator-activated receptor gamma (PPARG, PPARgamma) is a nuclear receptor that regulates expression of mediators of lipid metabolism and the inflammatory response. There is controversy over the pro-oncogenic or antioncogenic effects of PPARG, and little is known about its prognostic significance in colon cancer., Methods: Among 470 patients with colorectal cancer (stages I-IV) identified in 2 independent prospective cohorts, PPARG expression was detected in 102 tumors (22%) by immunohistochemistry. Cox proportional hazards models were used to compute hazard ratios (HRs) of colorectal cancer-specific and overall mortalities, adjusted for patient characteristics and molecular features including cyclooxygenase 2, fatty acid synthase, KRAS, BRAF, PIK3CA, p53, p21, beta-catenin, LINE-1 hypomethylation, microsatellite instability (MSI), and the CpG island methylation phenotype (CIMP)., Results: Compared with patients with PPARG-negative tumors, patients with PPARG-positive tumors had significantly lower overall mortality, determined by Kaplan-Meier analysis (P=.0047), univariate Cox regression (HR, 0.55; 95% confidence interval [CI], 0.37-0.84; P=.0053), and multivariate analysis (adjusted HR, 0.43; 95% CI, 0.27-0.69; P=.0004). Patients with PPARG-positive tumors experienced lower colorectal cancer-specific mortality (adjusted HR, 0.44; 95% CI, 0.25-0.79; P=.0054). The relationship between PPARG and lower mortality did not appear to be significantly modified by MSI, CIMP, LINE-1, or the other clinical and molecular variables examined (all P(interaction)>.05)., Conclusions: Tumor expression of PPARG is independently associated with longer survival of patients. PPARG expression appears to mark an indolent subset of colorectal cancers.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a metabolic regulator involved in maintaining glucose and fatty acid homeostasis. Besides its metabolic functions, the receptor has also been implicated in tumorigenesis. Ligands of PPARgamma induce apoptosis in several types of tumor cells, leading to the proposal that these ligands may be used as antineoplastic agents. However, apoptosis induction requires high doses of ligands, suggesting the effect may not be receptor-dependent. In this report, we show that PPARgamma is expressed in human primary T-cell lymphoma tissues and activation of PPARgamma with low doses of ligands protects lymphoma cells from serum starvation-induced apoptosis. The prosurvival effect of PPARgamma was linked to its actions on cellular metabolic activities. In serum-deprived cells, PPARgamma attenuated the decline in ATP, reduced mitochondrial hyperpolarization, and limited the amount of reactive oxygen species (ROS) in favor of cell survival. Moreover, PPARgamma regulated ROS through coordinated transcriptional control of a set of proteins and enzymes involved in ROS metabolism. Our study identified cell survival promotion as a novel activity of PPARgamma. These findings highlight the need for further investigation into the role of PPARgamma in cancer before widespread use of its agonists as anticancer therapeutics.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a metabolic regulator that plays an important role in sensitizing tissues to the action of insulin and in normalizing serum glucose and free fatty acids in type 2 diabetic patients. The receptor has also been implicated in the modulation of inflammatory responses, and ligands of PPARgamma have been found to induce apoptosis in lymphocytes. However, apoptosis induction may not depend on the receptor, because high doses of PPARgamma agonists are required for this process. Using cells containing or lacking PPARgamma, we reported previously that PPARgamma attenuates apoptosis induced by cytokine withdrawal in a murine lymphocytic cell line via a receptor-dependent mechanism. PPARgamma exerts this effect by enhancing the ability of cells to maintain their mitochondrial membrane potential during cytokine deprivation. In this report, we demonstrate that activation of PPARgamma also protects cells from serum starvation-induced apoptosis in human T lymphoma cell lines. Furthermore, we show that the survival effect of PPARgamma is mediated through its actions on cellular metabolic activities. In cytokine-deprived cells, PPARgamma attenuates the decline in ATP level and suppresses accumulation of reactive oxygen species (ROS). Moreover, PPARgamma regulates ROS through its coordinated transcriptional control of proteins and enzymes involved in ROS scavenging, including uncoupling protein 2, catalase, and copper zinc superoxide dismutase. Our studies identify cell survival promotion as a novel activity of PPARgamma and suggest that PPARgamma may modulate cytokine withdrawal-induced activated T cell death.

Quantitative monitoring of breakpoint cluster region (BCR)-Abelson kinase (ABL) transcripts has become indispensable in the clinical care of patients with chronic myelogenous leukemia. Because quantity and quality of RNA in clinical samples are highly variable, a suitable internal normalization control is required for accurate BCR-ABL quantification. However, few studies have examined suitability of the control genes using criteria relevant to residual disease testing. In this study, we evaluated a number of control genes with the application of several novel criteria, including control gene performance on serial patient sample testing and in a residual disease model. We also examined expression of the control genes in BCR-ABL-positive K562 cells in response to Gleevec treatment. We found that beta-glucuronidase is the best control gene among those studied. Importantly, ABL, a widely used control gene, generates misleading BCR-ABL changes that potentially affect the clinical management of chronic myelogenous leukemia patients.