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Contains fulltext : 71220.pdf (publisher's version ) (Closed access), This study was designed to identify highly recurrent genetic alterations typical of Sezary syndrome (Sz), an aggressive cutaneous T-cell lymphoma/leukemia, possibly revealing pathogenetic mechanisms and novel therapeutic targets. High-resolution array-based comparative genomic hybridization was done on malignant T cells from 20 patients. Expression levels of selected biologically relevant genes residing within loci with frequent copy number alteration were measured using quantitative PCR. Combined binary ratio labeling-fluorescence in situ hybridization karyotyping was done on malignant cells from five patients. Minimal common regions with copy number alteration occurring in at least 35% of patients harbored 15 bona fide oncogenes and 3 tumor suppressor genes. Based on the function of the identified oncogenes and tumor suppressor genes, at least three molecular mechanisms are relevant in the pathogenesis of Sz. First, gain of cMYC and loss of cMYC antagonists (MXI1 and MNT) were observed in 75% and 40% to 55% of patients, respectively, which were frequently associated with deregulated gene expression. The presence of cMYC/MAX protein heterodimers in Sezary cells was confirmed using a proximity ligation assay. Second, a region containing TP53 and genome maintenance genes (RPA1/HIC1) was lost in the majority of patients. Third, the interleukin 2 (IL-2) pathway was affected by gain of STAT3/STAT5 and IL-2 (receptor) genes in 75% and 30%, respectively, and loss of TCF8 and DUSP5 in at least 45% of patients. In sum, the Sz genome is characterized by gross chromosomal instability with highly recurrent gains and losses. Prominent among deregulated genes are those encoding cMYC, cMYC-regulating proteins, mediators of MYC-induced apoptosis, and IL-2 signaling pathway components.

Patients diagnosed with diffuse large B-cell lymphoma (DLBCL) show varying responses to conventional therapy, and this might be contributed to the differentiation stage of the tumor B-cells. The aim of the current study was to evaluate a panel of kinases (ZAP70, PKC-ß I and II and phosphorylated PKB/Akt) and phosphatases (PTEN, SHP1 and SHP2) known to be frequently deregulated in lymphoid malignancies. De novo DLBCL cases were divided into two subgroups, the germinal center (GC) group (14/28) and the non-germinal center (non-GC) or activated B-cell (ABC) group (14/28). ZAP70 and PKC-ß II were expressed in a significantly higher percentage of tumor cells in the clinically more aggressive non-GC group compared with the prognostically favourable GC group. Also, the subcellular localization of PKC-ß I and II differed in DLBCL cells, with the PKC-ß I isoform being expressed in both the cytoplasm and nucleus, while PKC-ß II was found exclusively in the cytoplasm. Loss of nuclear PTEN correlated with poor survival in cases from both subgroups. In addition, five cell lines of DLBCL origin were analyzed for protein expression and for mRNA levels of PTEN and SHP1. For the first time, we show that ZAP70 is expressed in a higher percentage of tumor cells in the aggressive non-GC subgroup of DLBCL and that PKC-ß I and II are differently distributed in the two prognostic subgroups of de novo DLBCL.

The immunoglobulin variable heavy chain (IgV(H)) gene mutation status is an important prognostic factor in chronic lymphocytic leukemia (CLL), since cases with mutated V-H genes show significantly longer survival than unmutated cases. Recently, we reported a preferential use of the V(H)3-21 gene in mutated CLL and showed that mutated V(H)3-21 cases had an inferior overall survival compared with other mutated CLL. In order to further characterize this subset, we performed VH gene analysis in 265 CLL cases and identified 31 V(H)3-21 cases (11.7%), 21 cases had mutated and 10 cases unmutated VH genes. Regardless Of VH gene mutation status, a poor overall survival was found in the VH3-21 cases with a median survival of 83 months. These survival data confirm that V(H)3-21 cases do not fit into the general prognostic grouping of mutated and unmutated CLL. A large fraction Of V(H)3-21 cases also demonstrated unique features with shorter lengths of the third complementarity determining region (CDR3) and CDR3s with highly homologous amino acid sequences. Furthermore, the V(H)3-21 cases showed a striking dominance of X light chain expression, and analysis of the Iglambda gene rearrangements revealed highly restricted use of the Vlambda2-14/J(lambda)3 genes in the majority of cases. Taken together, our new findings strengthen the suggestion that V(H)3-21-using cases comprise a new CLL entity, irrespective Of VH gene mutation status, and implicate that a common antigen epitope, perhaps of pathogenic significance, is recognized by the highly homologous V(H)3-21/V(lambda)2-14 Ig molecules expressed in individual tumors. (Blood. 2003,101:4952-4957).