Multiple HLA class I and II associations in classical Hodgkin lymphoma and EBV status defined subgroups.

The pathogenesis of classical Hodgkin lymphoma (cHL) involves environmental and genetic factors. To explore the role of the human leukocyte antigen (HLA) genes, we performed a case-control genotyping study in 338 Dutch cHL patients and more than 5000 controls using a PCR-based sequence-specific oligonucleotide probe hybridization approach. HLA-A68 and HLA-DR11 (5) were significantly increased in the cHL patient population compared with the controls. Three class II associations were observed in the EBV(-) cHL population with an increase of HLA-DR15 (2) and a decrease of HLA-DR4 and HLA-DR7. Allele frequencies of HLA-A1, HLA-B37, and HLA-DR10 were significantly increased in the EBV(+) cHL population; these alleles are in strong linkage disequilibrium and form a common haplotype in whites. The allele frequency of HLA-A2 was significantly decreased in the EBV(+) cHL population. Sequence-specific oligonucleotide probe analysis revealed significant differences between EBV(+) and EBV(-) cHL patients for 19 probes that discriminate between HLA-A*01 and HLA-A*02. In conclusion, the HLA-A1 and HLA-A2 antigens and not specific single nucleotide variants shared by multiple alleles are responsible for the association with EBV(+) cHL. Furthermore, several new protective and predisposing HLA class I and II associations for the EBV(+), the EBV(-), and the entire cHL population were identified.

Increasing the efficacy of CD20 antibody therapy through the engineering of a new type II anti-CD20 antibody with enhanced direct and immune effector cell-mediated B-cell cytotoxicity.

CD20 is an important target for the treatment of B-cell malignancies, including non-Hodgkin lymphoma as well as autoimmune disorders. B-cell depletion therapy using monoclonal antibodies against CD20, such as rituximab, has revolutionized the treatment of these disorders, greatly improving overall survival in patients. Here, we report the development of GA101 as the first Fc-engineered, type II humanized IgG1 antibody against CD20. Relative to rituximab, GA101 has increased direct and immune effector cell-mediated cytotoxicity and exhibits superior activity in cellular assays and whole blood B-cell depletion assays. In human lymphoma xenograft models, GA101 exhibits superior antitumor activity, resulting in the induction of complete tumor remission and increased overall survival. In nonhuman primates, GA101 demonstrates superior B cell-depleting activity in lymphoid tissue, including in lymph nodes and spleen. Taken together, these results provide compelling evidence for the development of GA101 as a promising new therapy for the treatment of B-cell disorders.

Expression of the c-Met oncogene by tumor cells predicts a favorable outcome in classical Hodgkin's lymphoma.

BACKGROUND: The c-Met signaling pathway regulates a variety of biological processes, including proliferation, survival and migration. Deregulated c-Met activation has been implicated in the pathogenesis and prognosis of many human malignancies. We studied the function and prognostic significance of c-Met and hepatocyte growth factor protein expression in patients with classical Hodgkin's lymphoma. DESIGN AND METHODS: Expression of c-Met and its ligand, hepatocyte growth factor, were determined by immunohistochemistry. Prognostic values were defined in cohorts of German and Dutch patients with classical Hodgkin's lymphoma. Functional studies were performed on Hodgkin's lymphoma cell lines. RESULTS: Expression of c-Met was detected in the tumor cells of 52% (80/153) of the patients and expression of its ligand, hepatocyte growth factor, in 8% (10/121) of the patients. c-Met expression correlated with a 5-year freedom from tumor progression of 94%, whereas lack of expression correlated with a 5-year freedom from tumor progression of 73% (P<0.001) in the combined cohort. In multivariate analysis both c-Met (hazard ratio 5.0, 95% confidence interval 1.9-13.3, P<0.001) and stage (hazard ratio 2.8, 95% confidence interval 1.2-6.4, P=0.014) were independent predictors for freedom from tumor progression. In functional studies activation with hepatocyte growth factor did not affect cell growth, while the c-Met inhibitor SU11274 suppressed cell growth by inducing G2/M cell cycle arrest. CONCLUSIONS: Although functional studies showed an oncogenic role of the hepatocyte growth factor/c-Met signaling pathway in cell cycle progression, expression of c-Met in tumor cells from patients with classical Hodgkin's lymphoma strongly correlated with a favorable prognosis in two independent cohorts.

MiR-17/106b seed family regulates p21 in Hodgkin's lymphoma.

Hodgkin's lymphoma (HL) is a B cell-derived lymphoma characterized by a minority of malignant Hodgkin Reed-Sternberg (HRS) cells that have lost their normal B cell phenotype. Alterations in the cell cycle and apoptosis pathways might contribute to their resistance to apoptosis and sustained cell cycle progression. A key player in both cell cycle arrest and apoptosis is CDKN1A, encoding p21$^{{\rm{waf/cip1}}}$ (p21). P21 is regulated by p53 and can function as a cell cycle inhibitor when in the nucleus or as an apoptosis inhibitor when localized in the cytoplasm. We observed expression of p53, p21 and p-p21 in a variable number of HRS cells in 24 of 40 cases. Expression of miR-17 and miR-106a was detected in HRS cells of 10 HL cases. MiR-17/106b seed family members, CDKN1A RNA and p21 protein levels were variable in HL cell lines. We showed effective targeting of the CDKN1A 3' UTR by miR-17/106b in HL cell lines in a luciferase reporter assay and up-regulation of p21 protein levels upon anti-miR-17 treatment of KM-H2 cells. Functional studies indicated a p21-mediated G(1) arrest after miR-17/106b down-regulation in KM-H2, whereas no G(1) arrest was observed for U-HO1 and L428. This difference could not be explained by differences in the 3' UTR, the cellular location of p21 or expression variation during cell cycle progression. A strong correlation was observed for the miR-17/106b:CDKN1A ratio and the responsiveness to miR-17 inhibition, ie a low ratio in KM-H2 and an extremely high ratio in the two unresponsive HL cell lines. In conclusion, we show that miR-17/106b regulates p21 protein levels in HL and that the effect of miR-17/106b-mediated inhibition depends on the miRNA : target gene ratio. Thus, in HL high miR-17/106b expression contributes to a dysfunctional p53 pathway and thereby also to the malignant phenotype.

Molecular characterization of the vascular features of focal nodular hyperplasia and hepatocellular adenoma: a role for angiopoietin-1.

UNLABELLED: Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are two hepatic nodular lesions of different etiologies. FNH, a polyclonal lesion, is assumed to be a regenerative reaction following a vascular injury, whereas HCA is a monoclonal, benign neoplastic lesion. In addition to features that are predominantly found in either FNH or HCA (e.g., dystrophic vessels in FNH and single arteries in HCA), FNH and HCA share morphological vascular abnormalities such as dilated sinusoids. We hypothesized that these anomalous vascular features are associated with altered expression of growth factors involved in vascular remodeling. This was based on reports of morphologically abnormal hepatic vasculature and nodular lesions in transgenic models of hepatocytic overexpression of angiopoietin-1 (Ang-1), a member of the angiopoietin family, which is crucially involved in vascular morphogenesis and homeostasis. We investigated gene and protein expression of members of the angiopoietin system and vascular endothelial growth factor A (VEGF-A) and its receptors in 9 FNH samples, 13 HCA samples, and 9 histologically normal livers. In comparison with normal samples, a significant increase in Ang-1 was found in FNH (P < 0.01) and HCA (P < 0.05), whereas no significant changes in Ang-2, receptor tyrosine kinase with immunoglobulin-like and EGF-like domains 2, VEGF-A, or vascular endothelial growth factor receptor 2 (VEGFR-2) were observed. CONCLUSION: Because of the different etiological contexts of a preceding vascular injury in FNH and a neoplastic growth in HCA, Ang-1 might exert different effects on the vasculature in these lesions. In FNH, it could predominantly stimulate recruitment of myofibroblasts and result in dystrophic vessels, whereas in HCA, it may drive vascular remodeling that produces enlarged vessels and arterial sprouting that generates single arteries.

Extracellular ligation-dependent CD45RB enzymatic activity negatively regulates lipid raft signal transduction.

CD45 is the most prominent membrane protein on lymphocytes. The function and regulation of this protein tyrosine phosphatase remain largely obscure, mainly because of the lack of a known ligand, and it still remains unknown whether such tyrosine phosphatases are subject to extracellular control at all. We report that an anti-CD45RB antibody (Ab) that prevents rejection and induces tolerance activates CD45RB tyrosine phosphatase enzymatic activity in T lymphocytes, allowing us to directly monitor the effects of increased CD45RB activity on signal transduction. Using both kinase substrate peptide arrays as well as conventional biochemistry, we also provide evidence of the various kinases involved in bringing about the inhibitory effect of this Ab on CD3-induced T-cell receptor signaling. Furthermore, we report that activated CD45RB translocates to lipid rafts and interferes with lipid raft localization and activation state of CD45 substrate Lck. Thus, these findings indeed prove that CD45 is subject to extracellular control and also define a novel mechanism by which receptor tyrosine phosphatases control lymphocyte biology and provide further insight into the intracellular signaling pathways effected by anti-CD45RB monoclonal Ab treatment.

A high throughput experimental approach to identify miRNA targets in human cells.

The study of human microRNAs is seriously hampered by the lack of proper tools allowing genome-wide identification of miRNA targets. We performed Ribonucleoprotein ImmunoPrecipitation-gene Chip (RIP-Chip) using antibodies against wild-type human Ago2 in untreated Hodgkin lymphoma (HL) cell lines. Ten to thirty percent of the gene transcripts from the genome were enriched in the Ago2-IP fraction of untreated cells, representing the HL miRNA-targetome. In silico analysis indicated that approximately 40% of these gene transcripts represent targets of the abundantly co-expressed miRNAs. To identify targets of miR-17/20/93/106, RIP-Chip with anti-miR-17/20/93/106 treated cells was performed and 1189 gene transcripts were identified. These genes were analyzed for miR-17/20/93/106 target sites in the 5'-UTRs, coding regions and 3'-UTRs. Fifty-one percent of them had miR-17/20/93/106 target sites in the 3'-UTR while 19% of them were predicted miR-17/20/93/106 targets by TargetScan. Luciferase reporter assay confirmed targeting of miR-17/20/93/106 to the 3'-UTRs of 8 out of 10 genes. In conclusion, we report a method which can establish the miRNA-targetome in untreated human cells and identify miRNA specific targets in a high throughput manner. This approach is applicable to identify miRNA targets in any human tissue sample or purified cell population in an unbiased and physiologically relevant manner.

Hepatocellular carcinomas in cirrhotic and noncirrhotic human livers share angiogenic characteristics.

BACKGROUND: The antiangiogenic drug sorafenib has been shown to be an effective treatment for hepatocellular carcinoma (HCC) in patients with liver cirrhosis. It might also be effective in noncirrhotic HCC provided that the angiogenic properties of both tumor types are comparable. The aim of this study is to compare endothelial cell dynamics, microvessel density (MVD), and vessel maturation as indirect markers of angiogenesis in human HCC in cirrhotic and noncirrhotic livers. MATERIALS AND METHODS: In a tertiary care setting, 70 consecutive HCC tumors were analyzed for endothelial cell dynamics. CD34 was applied to identify tumor microvessels, double immunolabeling Ki67/CD34 and activated caspase-3/CD34 to assess endothelial cell proliferation and apoptosis, and alpha-smooth muscle actin/CD34 for pericyte coverage. These characteristics were compared in cirrhotic (n = 33) and noncirrhotic HCCs (n = 37). Microvessel density was correlated with radiological signs of hypervascularity as obtained with dynamic four-phase CT scans during the arterial and portal phase of contrast enhancement. RESULTS: Microvessels in cirrhotic and noncirrhotic HCC were mainly mature. In both groups endothelial cell turnover was low and MVD was not different. There was no correlation between MVD and venous invasion, tumor size, and turnover of tumor cells or endothelial cells. MVD was negatively correlated with contrast washout in the portal venous phase of CT scanning. In transplanted patients, MVD was not correlated with survival, whereas in patients after liver resection a high MVD was associated with a better prognosis. CONCLUSION: Angiogenic characteristics of HCC in cirrhotic and noncirrhotic livers have a remarkable similarity.

miRNA profiling of B-cell subsets: specific miRNA profile for germinal center B cells with variation between centroblasts and centrocytes.

MicroRNAs (miRNAs) are an important class of small RNAs that regulate gene expression at the post-transcriptional level. It has become evident that miRNAs are involved in hematopoiesis, and that deregulation of miRNAs may give rise to hematopoietic malignancies. The aim of our study was to establish miRNA profiles of naïve, germinal center (GC) and memory B cells, and validate their expression patterns in normal lymphoid tissues. Quantitative (q) RT-PCR profiling revealed that several miRNAs were elevated in GC B cells, including miR-17-5p, miR-106a and miR-181b. One of the most abundant miRNAs in all three B-cell subsets analyzed was miR-150, with a more than 10-fold lower level in GC B cell as compared with the other two subsets. miRNA in situ hybridization (ISH) in tonsil tissue sections confirmed the findings from the profiling work. Interestingly, gradual decrease of miR-17-5p, miR-106a and miR-181b staining intensity from the dark to the light zone was observed in GC. A strong cytoplasmic staining of miR-150 was observed in a minority of the centroblasts in the dark zone of the GC. Inverse staining pattern of miR-150 against c-Myb and Survivin was observed in tonsil tissue sections, suggesting possible targeting of these genes by miR-150. In line with this, the experimental induction of miR-150 lead to reduced c-Myb, Survivin and Foxp1 expression levels in the Burkitt's lymphoma cell line, DG75. In conclusion, miRNA profiles of naïve, GC and memory B cells were established and validated by miRNA ISH. Within the GC cells, a marked difference was observed between the light and the dark zone.

The angiogenic makeup of human hepatocellular carcinoma does not favor vascular endothelial growth factor/angiopoietin-driven sprouting neovascularization.

UNLABELLED: Quantitative data on the expression of multiple factors that control angiogenesis in hepatocellular carcinoma (HCC) are limited. A better understanding of the mechanisms underlying angiogenesis in HCC will improve the rational choice of anti-angiogenic treatment. We quantified gene and protein expression of members of the vascular endothelial growth factor (VEGF) and angiopoietin systems and studied localization of VEGF, its receptors VEGFR-1 and VEGFR-2, Angiopoietin (Ang)-1 and Ang-2, and their receptor, in HCC in noncirrhotic and cirrhotic livers. We employed real-time reverse transcription polymerase chain reaction (RT-PCR), western blot, and immunohistology, and compared the outcome with highly angiogenic human renal cell carcinoma (RCC). HCC in noncirrhotic and cirrhotic livers expressed VEGF and its receptors to a similar extent as normal liver, although in cirrhotic background, VEGFR-2 levels in both tumor and adjacent tissue were decreased. Ang-1 expression was slightly increased compared with normal liver, whereas Tie-2 was strongly down-regulated in the tumor vasculature. Ang-2 messenger RNA (mRNA) levels were also low in HCCs of both noncirrhotic and cirrhotic livers, implying that VEGF-driven angiogenic sprouting accompanied by angiopoietin-driven vascular destabilization is not pronounced. In RCC, VEGF-A levels were one order of magnitude higher. At the same time, endothelially expressed Ang-2 was over 30-fold increased compared with expression in normal kidney, whereas Ang-1 expression was decreased. CONCLUSION: In hepatocellular carcinoma, tumor vascularization is not per se VEGF/angiopoietin driven. However, increased CD31 expression and morphological changes representative of sinusoidal capillarization in tumor vasculature indicate that vascular remodeling is taking place. This portends that therapeutic intervention of HCC at the level of the vasculature is optional, and that further studies into the molecular control thereof are warranted.

The CD4+CD26- T-cell population in classical Hodgkin's lymphoma displays a distinctive regulatory T-cell profile.

Little is known about the gene expression profile and significance of the rosetting CD4+CD26- T cells in classical Hodgkin's lymphoma (cHL). To characterize these T cells, CD4+CD26- and CD4+CD26+ T-cell populations were sorted from lymph node (LN) cell suspensions from nodular sclerosis HL (NSHL) and reactive LNs. mRNA profiles of stimulated and resting cell subsets were evaluated with quantitative RT-PCR for 46 genes. We observed a higher percentage of CD4+CD26- T cells in NSHL than in reactive LNs. The resting CD4+CD26- T cells in NSHL showed higher mRNA levels of CD25, CTLA4, OX40 and CCR4 compared with in LNs, supporting a regulatory T-cell (Treg) type, and this was validated by immunohistochemistry. Moreover, these cells showed low or no expression of the Th1- or Th2-related cytokines IL-2, IFN-gamma, IL-13, IL-12B, IL-4, and IL-5, and the chemoattractant receptor CRTH2. Besides Tregs, Th17 cells may exist in NSHL based on the significantly higher IL-17 mRNA level for both T-cell populations in NSHL. Upon stimulation in vitro, lack of upregulation of mRNA levels of most cytokine genes indicated an anergic character for the CD4+CD26- T-cell subset. Anergy fits with the Treg profile of these cells, probably explaining the immunosuppressive mechanism involved in NSHL.

Serum chemokine levels in Hodgkin lymphoma patients: highly increased levels of CCL17 and CCL22.

Hodgkin lymphoma (HL) is characterized by a minority of neoplastic Hodgkin-Reed Sternberg (HRS) cells surrounded by a non-neoplastic reactive infiltrate. As immunological mechanisms appear to be crucial in classical HL pathogenesis, altered serum chemokine levels might be related to disease activity. Serum levels of nine chemokines were examined in 163 untreated HL patients and 334 controls. We investigated single nucleotide polymorphisms (SNPs) for association with serum CCL17 (thymus and activation-regulated chemokine, TARC) levels and HL susceptibility. Serum CCL17 and CCL22 (macrophage-derived chemokine, MDC) levels were significantly increased in 82% and 57% of the HL patients. Nodular sclerosis cases showed increased serum CCL17 and CCL22 levels (P < 0.001) and serum levels were correlated with Ann Arbor stage. Of nine patients with pre- and post-treatment serum samples, the majority showed decreased CCL17 and CCL22 levels after treatment. HRS cells expressed CCL17 and CCL22 in 77% and 75% of 74 cases. Three SNPs showed a trend of increased serum CCL17 levels with minor alleles in controls, but were not associated with HL susceptibility. CCL17 and CCL22 were the only chemokines with increased serum levels in the vast majority of HL patients, which provides further insight into the molecular mechanism(s) leading to infiltrations of reactive lymphocytes in HL.

ATR alterations in Hodgkin's lymphoma.

Hodgkin's lymphoma (HL) is characterized by the presence of neoplastic Hodgkin and Reed-Sternberg cells (HRSC) in a background of inflammatory cells. Free radicals and oxidative stress generated in the inflammatory lesions could cause DNA damage, thus providing a basis for lymphomagenesis. Ataxia-telangiectasia mutated (ATM) and Rad3-related (ATR) genes are responsive genes for DNA damage, therefore the potential involvement of the ATR gene in HL pathogenesis was examined in 8 HL cell lines and 7 clinical cases. ATR alterations were detected in 6 out of 8 HL lines. Most aberrant transcripts observed were heterozygous deletions, which may have resulted from aberrant splicing. ATR aberrant transcripts were also detected in 3 out of 7 clinical cases. Three alterations, del exon 4, deletion exon 29-34 and insertion of 137 bp in exon 46/47 were commonly observed in both cell lines and clinical samples. HL cells with ATR alterations except del exon 4 showed a delay/abrogation in repair for DNA double-strand breaks (DSBs) and single-strand break (SSB) as well as exhibiting a defect in p53 accumulation. These findings suggested the role of ATR gene alterations in HL lymphomagenesis.

Strongly enhanced IL-10 production using stable galectin-1 homodimers.

Galectin-1 is the homodimeric form of a protein, which is present in a dynamic equilibrium with the beta-galactoside monomeric form and has potent anti-inflammatory and immunomodulating effects. These favorable effects are probably related to the induction of apoptosis in activated T cells and the induction of IL-10, which have been demonstrated to be characteristic for the dimeric form of the protein. Based on these findings it can be speculated that the in vivo effects of galectin-1 can be improved by the generation of stable galectin-1 homodimers (dGal). To test this hypothesis we produced leucine-zipper based stable galectin-1 homodimers and tested its apoptosis inducing effects on MOLT-4 cells and its immunomodulatory effects in vitro on PBMC of five independent donors. Phosphatidylserine exposure and a drop in mitochondrial membrane potential was strongly enhanced on MOLT-4 cells upon treatment with dGal as compared to wtGal. The minimal effective concentration was 20-fold reduced as compared to the minimal effective wtGal concentration. dGal showed enhanced induction of IL-10 on total PBMC as compared to treatment with wild-type protein (wtGal). The minimal effective dGal concentration was 100-fold lower than that of wtGal. Of the purified cell populations monocytes are the strongest IL-10 producers, whereas T cells induce IL-10 at a lower level and no induction is observed in B cells. Besides induction of IL-10, dGal caused an increase in IL-1beta production in all donors and a reduction of IL-2 production in 3 out of 5 donors, whereas no consistent changes were observed for other inflammatory cytokines. In summary, we demonstrated that dGal shows enhanced effects at strongly reduced concentrations. Application of dGal may therefore serve as an improved treatment of chronic inflammatory diseases.

Hodgkin's lymphoma associated T-cells exhibit a transcription factor profile consistent with distinct lymphoid compartments.

BACKGROUND: Hodgkin's lymphoma (HL) is characterised by an ineffective immune response that is predominantly mediated by CD4+ T-cells. AIMS: To analyse the expression of the key regulatory T-cell transcription factors (TFs) in the T-cells of HL involved tissues in order to assess the nature of the T(H) immune response in HL. METHODS AND RESULTS: By immunohistochemistry, GATA3 was strongly and T-bet exclusively expressed in a subset of interfollicular lymphocytes in the reactive lymphoid tissues. In classical HL (CHL), which is generally located in the interfollicular zones, a predominance of T-bet+ T-cells and lesser amounts of GATA3+ and c-Maf+ T-cells was found, concordant with the pattern of the normal interfollicular compartment. In reactive lymphoid tissues, c-Maf was observed mostly in T-lymphocytes within the germinal centres (GCs). Nodular lymphocyte predominance type of Hodgkin's lymphoma (NLPHL) and progressively transformed germinal centres cases, showed a majority of c-Maf+ T-cells, consistent with the pattern in normal GCs. NLPHL cases uniformly showed c-Maf+/CD57+ T-cell rosettes around the neoplastic cells; these rosettes were absent in "paragranuloma-type" T-cell/histiocyte rich B-cell lymphoma. CONCLUSIONS: T-cell TF expression profiles of the reactive T-cells in both subtypes of HL are in accordance with the expression profile observed in the distinct lymphoid compartments.

The human leukocyte antigen class I region is associated with EBV-positive Hodgkin's lymphoma: HLA-A and HLA complex group 9 are putative candidate genes.

Various studies have indicated that the human leukocyte antigen (HLA) region is associated with Hodgkin's lymphoma. We recently showed a specific association of the HLA class I region with EBV-positive Hodgkin's lymphoma cases. One haplotype of two consecutive microsatellite markers (D6S265 and D6S510) was overrepresented in the patient group, whereas another haplotype was underrepresented. Here, we did fine mapping of this region of approximately 400 kb as a next step to find the causative single-nucleotide polymorphism(s) (SNP). To select candidate SNPs for screening the total study population, several known SNPs were determined by sequencing two individuals homozygous for either of the above-mentioned associated haplotypes. Seven SNPs displayed different alleles in these two individuals and were therefore analyzed in the total study population, including 238 Hodgkin's lymphoma patients and 365 family-based controls. All seven SNPs showed significant association with the EBV-positive patient group. Two of these SNPs were analyzed in a Scottish Hodgkin's lymphoma population and revealed significant associations as well. The associated SNPs are located nearby two putative candidate genes: HLA-A and HLA complex group 9. HLA-A represents the most interesting target because of its consistent expression in EBV-positive Hodgkin's lymphoma cases and its ability to present EBV-derived peptides to cytotoxic T cells.

Expression of retinoblastoma protein and P16 proteins in classic Hodgkin lymphoma: relationship with expression of p53 and presence of Epstein-Barr virus in the regulation of cell growth and death.

Deregulation of several genes involved in cell cycle control has been reported in classic Hodgkin lymphoma (cHL). This study aimed to investigate the expression of tumor suppressor proteins (P16(INK4A), retinoblastoma protein, and p53) in cHL in relation to the proliferation and apoptosis of Hodgkin/Reed-Sternberg (H/RS) cells, correlating with the status of Epstein-Barr virus (EBV). A total of 66 cHL cases and 10 nonneoplastic reactive lymphoid tissues were retrieved from the archives. Immunohistochemistry technique was used for the detection of protein expression. Presence of EBV infection was detected by EBV early RNA in situ hybridization. p16(INK4A) gene deletion status was assessed by fluorescence in situ hybridization technique. Expression of P16(INK4A) was observed in 49.2% of the cases, whereas positive retinoblastoma protein and p53 expressions in the H/RS cells were detected in 89.1% and 81.5% of the cases, respectively. Epstein-Barr virus positivity was detected in 53.0% of the cases. Proliferation marker, Ki-67 expression, was observed in 86.7% of the cases. There was no significant correlation between the expression of the various tumor suppressor proteins and Ki-67. Retinoblastoma protein and p53 were also not associated with the presence of EBV. An inverse relationship was observed between the expression of P16(INK4A) and the presence of EBV. There were no significant homozygous or hemizygous deletions of the p16(INK4A) gene. However, an aberrant copy number of chromosome 9 with the loss of one or more p16(INK4A) loci was detected in all cases assessable by fluorescence in situ hybridization. Loss of function of one or more tumor suppressor proteins may be involved in defective cell regulation of H/RS cells. Epstein-Barr virus may have a role in inhibiting P16(INK4A) expression, thus resulting in a perturbed p16(INK4A)-Rb cell cycle checkpoint.

Molecular, cytogenetic, and immunophenotypic characterization of follicular lymphoma grade 3B; a separate entity or part of the spectrum of diffuse large B-cell lymphoma or follicular lymphoma?

We studied a histological homogeneous group of 29 cases with the diagnosis of follicular lymphoma (FL) grade 3B (FL3Bs). In a previous study, we subdivided this group in 3 subgroups based on (1) aberrations of the 3q27 region, (2) lack of 3q27 and t(14;18), and (3) the presence of a t(14;18). In this study, we further characterized the FL3B lymphomas that are currently part of the spectrum of FL in the WHO classification, taking into account other cytogenetical aberrations, immunohistochemistry for P53, bcl2, bcl6, and CD10, rearrangement of the proto-oncogene myc, and mutation of the tumor suppressor gene TP53. With respect to P53, bcl2, bcl6 expression, myc rearrangement, and TP53 mutation, FL3B represents a homogeneous group. CD10 expression and gain of chromosome 7, considered to be typical FL markers, were more common in the FL3B t(14;18)-positive subgroup. The lack of CD10 expression and gain of chromosome 7 in most cases in the other 2 subgroups suggest that those cases have a closer relation to diffuse large B-cell lymphomas.

BCL6 alternative breakpoint region break and homozygous deletion of 17q24 in the nodular lymphocyte predominance type of Hodgkin's lymphoma-derived cell line DEV.

DEV is the only cell line derived from nodular lymphocyte predominance type of Hodgkin's lymphoma (NLPHL); however, a comprehensive report about the genetic and immunophenotypic profile of this unique cell line is lacking. We analyzed DEV with respect to immunophenotype and genetic aberrations. The immunostaining revealed positivity for CD45, CD20, CD22, CD79a, IgA2, CD80, CD86, CD74, and BCL6. Cytogenetically, DEV has complex chromosome 3 translocations involving chromosomes 7, 14, and 22. A detailed analysis of the 3q27 breakpoint of the der(3)t(3;14)(p14;q32)t(3;22)(q27;q11.2) revealed a break in the BCL6 alternative breakpoint region. Using array comparative genomic hybridization, a 3-megabase homozygous deletion at 17q24.1-24.2 was identified. Fluorescence in situ hybridization indicated the presence of 2 chromosome 17 homologues, each of which carried a small interstitial deletion. Eight microsatellite markers flanking the homozygously deleted region all showed a homozygous pattern suggesting loss of one of the parental alleles. D17S1809 and D17S1816 could not be amplified using DEV DNA, in keeping with a location within the homozygously deleted segment. In conclusion, DEV has an immunophenotype that is consistent with the neoplastic cells of NLPHL cases, the lymphocytic and histiocytic cells. We demonstrated involvement of the BCL6 gene based on the presence of a breakpoint in the alternative breakpoint region and nuclear staining for BCL6 protein and identified a homozygously deleted region at 17q24.