Prognostic and therapeutic implications of genetic aberrations in childhood acute lymphoblastic leukemia

Do transformacji nowotworowej w ostrej białaczce limfoblastycznej (ALL) dochodzi wskutek co najmniej dwóch następujących po sobie mutacji, które wspólnie inicjują i promują leukemogenezę. Spektrum zaburzeń struktury zmutowanych genów obejmuje zarówno mutacje punktowe, jak i pęknięcia dwuniciowego DNA, prowadzące do translokacji, delecji, inwersji lub duplikacji regionu kodującego. Niektóre spośród odkrytych zaburzeń w genomie limfoblast ów mają niezależne znaczenie prognostyczne stratyfikujące ryzyko niepowodzenia terapii w dziecięcej ALL. W niniejszej pracy omówiono je wraz ze wskazaniem potencjalnych implikacji terapeutycznych opartych na mechanizmach molekularnych Hematologia 2011; 2, 1: 43–50The process of malignant transformation in childhood acute lymphoblastic leukemia (ALL) requires at least two subsequent mutations which initiate and promote leukemogenesis. These genetic aberrations include point-mutations as well as double-strand DNA breaks leading to various types of chromosomal rearrangements of the coding regions. Some of the genetic lesions are independent prognostic factors, which effectively stratify the risk of treatment outcome. In this review we summarize the most common genetic aberrations in childhood ALL which may provide potential molecular target for novel therapies. Hematologia 2011; 2, 1: 43–5

Genetic susceptibility to acute lymphoblastic leukemia pre- and post genome-wide association studies era

Analiza predyspozycji genetycznej w patogenezie ostrej białaczki limfoblastycznej (ALL) jesttrudna ze względu na bardzo niską zachorowalność w ogólnej populacji. Prowadzone przezlata analizy populacyjnej zmienności genów kandydatów wskazywały na wiele regionów związanychz zachorowaniem na ALL, takich jak geny kodujące białka zaangażowane w metabolizmkarcynogenów czy białka szlaków naprawy DNA. Wyników tych badań często nie replikowanow innych populacjach. Przełom nastąpił w momencie wprowadzenia badań zmiennościcałego genomu, czyli jednoczesnego badania 500 000–2 000 000 mln polimorfizmów w populacjachprzekraczających 1000 pacjentów. Metoda ta pozwoliła na zidentyfikowanie kilku miejscw genomie, które są związane z patogenezą ALL, a wyniki tych badań potwierdzono w wielupopulacjach. Należy podkreślić, że większość genów (IKZF1, ARID5B i CEPBE) wiąże sięz różnicowaniem limfocytów, co rzuca nowe światło na patogenezę ALL u dzieci i wskazuje, żew tej chorobie może dochodzić do genetycznie uwarunkowanego zaburzenia różnicowania limfocytówlub/i zaburzeń immunologicznych prowadzących do nieefektywnej eliminacji klonówbiałaczkowych.Analysis of genetic predisposition in pathogenesis of acute lymphoblastic leukemia (ALL) isvery difficult because of very low rate of morbidity in general population. Candidate geneapproaches have revealed many loci associated with ALL e.g. genes encoding proteins takingpart in carcinogen metabolism or DNA repairing pathways. Results of these studies often werenot replicated in other populations. The breakthrough took place at the moment of introductionof genome-wide association studies, which allow to analyze 500 000–2 000 000 polymorphicsites in population exceeding 1000 people. This method contributed to identification of newregions in the genome, that are related to ALL pathogenesis and results of these studies were confirmed in other populations. Interestingly, the most of these genes (IKZF1, ARID5B,CEBPE) are involved in the regulation of lymphocytes differentiation which sheds a new lighton unknown aspects of pathogenesis of ALL in children. It seems that in ALL may occur asa result of genetically determined disturbance of lymphocytes differentiation or/and inheritedimmunological dysfunctions leading to inefficient elimination of leukemic clones

Molecular background and therapeutic perspectives of acute lymphoblastic leukemia BCR-ABL1-like

Białaczka BCR-ABL1-like jest nowo wyodrębnionym podtypem ostrej białaczki limfoblastycznej (ALL) wysokiego ryzyka, wywodzącym się z komórek prekursorowych limfocytów B (BCP-ALL), który charakteryzuje profil ekspresji genów podobny do białaczki Philadelphia-pozytywnej mimo braku fuzji genów BCR-ABL1. Częstość występowania na poziomie 15% oraz wysokie ryzyko wznowy i zgonu w przypadkach BCR-ABL1-like skłania do eksplorowania podłoża molekularnego tego nowotworu oraz opracowywania nowych strategii terapeutycznych. Około 80% zaburzeń genetycznych obserwowanych w BCR-ABL1-like ALL dotyczy genów zaangażowanych w różnicowaniei dojrzewanie linii B (IKZF1, PAX5, E2A, EBF1 i VPREB1), a także regulujących procesy proliferacjilimfocytów B (CRLF2, CDKN2A/2B). Specyficzne dla tego podtypu białaczki są też fuzje genów PDGFRB, ABL1, JAK prowadzące do aktywacji kinaz szlaków metabolicznych promujących nowotworzenie. Wiele spośród zidentyfikowanych, nadaktywnych ścieżek sygnałowych może być hamowanych za pomocą dostępnych leków ukierunkowanych molekularnie.BCR-ABL1-like acute lymphoblastic leukemia (ALL) is newly identified subtype of high-risk B-cell progenitor acute lymphoblastic leukemia (BCP-ALL), which exhibit gene expression signature similar to that of BCR-ABL1–positive leukemia, but without characteristic BCR-ABL1 gene fusion. Since the frequency of the BCR-ABL1-like ALL is relatively high (15%) and the risk of relapse issignificantly increased, molecular pathogenesis of this subtype is widely explored. Approximately 80% of genetic lesions in the BCR-ABL1-like ALL refer to genes involved in B-cell differentiation and maturation (IKZF1, PAX5, E2A, EBF1 and VPREB1) as well as to genes that regulateB-lymphocyte proliferation (CRLF2, CDKN2A/2B). Moreover, BCR-ABL1-like ALL is also characterized by gene fusions involving PDGFRB, ABL1, JAK genes which activate kinases of specific,metabolic pathways responsible for cancer development. Many of identified up-regulated signaling pathways can be inhibited by currently clinically available molecular targeted drugs

Onkogenne zaburzenia molekularne w podtypach chłoniaków rozlanych z dużych komórek B

Diffuse large B-cell lymphoma (DLBCL), which is characterized by the uncontrolled growth of mature, peripheral B-cells, constitutes a group of heterogeneous diseases in terms of morphological, biological and clinical features. The classification of DLBCL based on the location of the tumor, his­topathology, immunophenotype, etiology, and similarity to other diseases of the B lymphocytes. This review presents an update on the molecular abnormalities identified in the major subtypes of the disease, e.g. germinal center B-cell and activated B-cell, and their importance in context of the clinical course of disease.Chłoniaki rozlane z dużych komórek B (DLBCL), charakteryzujące się niekontrolowanym wzro­stem dojrzałych, obwodowych limfocytów B, to grupa chorób heterogennych, zarówno pod względem morfologicznym, biologicznym, jak i klinicznym. Podstawę podziału DLBCL na poszczególne podgrupy stanowi lokalizacja nowotworu, jego histopatologia, immunofenotyp, etiologia oraz podo­bieństwo do innych chorób układu chłonnego. W niniejszej pracy zaprezentowano najnowsze donie­sienia dotyczące zaburzeń molekularnych identyfikowanych w poszczególnych podtypach choroby; w postaciach DLBCL wywodzących się z ośrodków rozmnażania oraz DLBCL z aktywowanych komórek B, ze szczególnym uwzględnieniem znaczenia prognostycznego tych defektów

The role of histone protein modifications and mutations in histone modifiers in pediatric b-cell progenitor acute lymphoblastic leukemia

While cancer has been long recognized as a disease of the genome, the importance of epigenetic mechanisms in neoplasia was acknowledged more recently. The most active epigenetic marks are DNA methylation and histone protein modifications and they are involved in basic biological phenomena in every cell. Their role in tumorigenesis is stressed by recent unbiased large-scale studies providing evidence that several epigenetic modifiers are recurrently mutated or frequently dysregulated in multiple cancers. The interest in epigenetic marks is especially due to the fact that they are potentially reversible and thus druggable. In B-cell progenitor acute lymphoblastic leukemia (BCP-ALL) there is a relative paucity of reports on the role of histone protein modifications (acetylation, methylation, phosphorylation) as compared to acute myeloid leukemia, T-cell ALL, or other hematologic cancers, and in this setting chromatin modifications are relatively less well studied and reviewed than DNA methylation. In this paper, we discuss the biomarker associations and evidence for a driver role of dysregulated global and loci-specific histone marks, as well as mutations in epigenetic modifiers in BCP-ALL. Examples of chromatin modifiers recurrently mutated/disrupted in BCP-ALL and associated with disease outcomes include MLL1, CREBBP, NSD2, and SETD2. Altered histone marks and histone modifiers and readers may play a particular role in disease chemoresistance and relapse. We also suggest that epigenetic regulation of B-cell differentiation may have parallel roles in leukemogenesis

Raman-based spectrophenotyping of the most important cells of the immune system

INTRODUCTION: Human peripheral blood mononuclear cells (PBMCs) are a heterogeneous population of cells that includes T and B lymphocytes. The total number of lymphocytes and their percentage in the blood can be a marker for the diagnosis of several human diseases. Currently, cytometric methods are widely used to distinguish subtypes of leukocytes and quantify their number. These techniques use cell immunophenotyping, which is limited by the number of fluorochrome-labeled antibodies that can be applied simultaneously. OBJECTIVE: B and T lymphocytes were isolated from peripheral blood obtained from healthy human donors. METHODS: The immunomagnetic negative selection was used for the enrichment of B and T cells fractions, and their purity was assessed by flow cytometry. Isolated cells were fixed with 0.5% glutaraldehyde and measured using confocal Raman imaging. K-means cluster analysis, principal component analysis and partial least squares discriminant methods were applied for the identification of spectroscopic markers to distinguish B and T cells. HPLC was the reference method for identifying carotene in T cells. RESULTS: Reliable discrimination between T and B lymphocytes based on their spectral profile has been demonstrated using label-free Raman imaging and chemometric analysis. The presence of carotene in T lymphocytes (in addition to the previously reported in plasma) was confirmed and for the first time unequivocally identified as β-carotene. In addition, the molecular features of the lymphocytes nuclei were found to support the discriminant analysis. It has been shown that although the presence of carotenoids in T cells depends on individual donor variability, the reliable differentiation between lymphocytes is possible based on Raman spectra collected from individual cells. CONCLUSIONS: This proves the potential of Raman spectroscopy in clinical diagnostics to automatically differentiate between cells that are an important component of our immune system

Influence of genomic variation in FTO at 16q12.2, MC4R at 18q22 and NRXN3 at 14q31 genes on breast cancer risk

Breast cancer is a major cause of cancer-related deaths in women. It is known that obesity is one of the risk factors of breast cancer. The subject of our interest was genes: FTO, MC4R and NRXN3–associated with obesity. In this study we have analyzed frequencies of genomic variants in FTO, MC4R and NRXN3 in the group of 134 breast cancer patients. We genotyped two polymorphic sites located in FTO gene (rs993909 and rs9930506), one polymorphic site of MC4R gene (rs17782313) and one polymorphic site of NRXN3 gene (rs10146997). Our hypothesis was that above mentioned SNPs could participate in carcinogenesis. Our research has showed that only rs10146997 was significantly (P = 0.0445) associated with higher risk of breast cancer development (OR = 0.66 (95% CI 0.44–0.99)). Moreover, G allele carriers in rs10146997 of the NRXN3 gene were the youngest patients at onset of breast cancer. On the basis of our research we suggest that further functional may elucidate the role of genomic variation in breast cancer development

Validation of the United Kingdom copy-number alteration classifier in 3239 children with B-cell precursor ALL

Genetic abnormalities provide vital diagnostic and prognostic information in pediatric acute lymphoblastic leukemia (ALL) and are increasingly used to assign patients to risk groups. We recently proposed a novel classifier based on the copy-number alteration (CNA) profile of the 8 most commonly deleted genes in B-cell precursor ALL. This classifier defined 3 CNA subgroups in consecutive UK trials and was able to discriminate patients with intermediate-risk cytogenetics. In this study, we sought to validate the United Kingdom ALL (UKALL)-CNA classifier and reevaluate the interaction with cytogenetic risk groups using individual patient data from 3239 cases collected from 12 groups within the International BFM Study Group. The classifier was validated and defined 3 risk groups with distinct event-free survival (EFS) rates: good (88%), intermediate (76%), and poor (68%) (P < .001). There was no evidence of heterogeneity, even within trials that used minimal residual disease to guide therapy. By integrating CNA and cytogenetic data, we replicated our original key observation that patients with intermediate-risk cytogenetics can be stratified into 2 prognostic subgroups. Group A had an EFS rate of 86% (similar to patients with good-risk cytogenetics), while group B patients had a significantly inferior rate (73%, P < .001). Finally, we revised the overall genetic classification by defining 4 risk groups with distinct EFS rates: very good (91%), good (81%), intermediate (73%), and poor (54%), P < .001. In conclusion, the UKALL-CNA classifier is a robust prognostic tool that can be deployed in different trial settings and used to refine established cytogenetic risk groups

Mechanisms of Immune Evasion in Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) results from a clonal expansion of abnormal lymphoid progenitors of B cell (BCP-ALL) or T cell (T-ALL) origin that invade bone marrow, peripheral blood, and extramedullary sites. Leukemic cells, apart from their oncogene-driven ability to proliferate and avoid differentiation, also change the phenotype and function of innate and adaptive immune cells, leading to escape from the immune surveillance. In this review, we provide an overview of the genetic heterogeneity and treatment of BCP- and T-ALL. We outline the interactions of leukemic cells in the bone marrow microenvironment, mainly with mesenchymal stem cells and immune cells. We describe the mechanisms by which ALL cells escape from immune recognition and elimination by the immune system. We focus on the alterations in ALL cells, such as overexpression of ligands for various inhibitory receptors, including anti-phagocytic receptors on macrophages, NK cell inhibitory receptors, as well as T cell immune checkpoints. In addition, we describe how developing leukemia shapes the bone marrow microenvironment and alters the function of immune cells. Finally, we emphasize that an immunosuppressive microenvironment can reduce the efficacy of chemo- and immunotherapy and provide examples of preclinical studies showing strategies for improving ALL treatment by targeting these immunosuppressive interactions