Valproate and Retinoic Acid in Combination With Decitabine in Elderly Nonfit Patients With Acute Myeloid Leukemia: Results of a Multicenter, Randomized, 2 × 2, Phase II Trial.

PURPOSE: DNA-hypomethylating agents are studied in combination with other epigenetic drugs, such as histone deacetylase inhibitors or differentiation inducers (eg, retinoids), in myeloid neoplasias. A randomized, phase II trial with a 2 × 2 factorial design was conducted to investigate the effects of the histone deacetylase inhibitor valproate and all-trans retinoic acid (ATRA) in treatment-naive elderly patients with acute myeloid leukemia (AML). PATIENTS AND METHODS: Two hundred patients (median age, 76 years; range, 61-92 years) ineligible for induction chemotherapy received decitabine (20 mg/m2 intravenously, days 1 to 5) alone (n = 47) or in combination with valproate (n = 57), ATRA (n = 46), or valproate + ATRA (n = 50). The primary endpoint was objective response, defined as complete and partial remission, tested at a one-sided significance level of α = .10. Key secondary endpoints were overall survival, event-free survival, and progression-free survival and safety. RESULTS: The addition of ATRA resulted in a higher remission rate (21.9% with ATRA v 13.5% without ATRA; odds ratio, 1.80; 95% CI, 0.86 to 3.79; one-sided P = .06). For valproate, no effect was observed (17.8% with valproate v 17.2% without valproate; odds ratio, 1.06; 95% CI, 0.51 to 2.21; one-sided P = .44). Median overall survival was 8.2 months with ATRA v 5.1 months without ATRA (hazard ratio, 0.65; 95% CI, 0.48 to 0.89; two-sided P = .006). Improved survival was observed across risk groups, including patients with adverse cytogenetics, and was associated with longer response duration. With valproate, no survival difference was observed. Toxicities were predominantly hematologic, without relevant differences between the 4 arms. CONCLUSION: The addition of ATRA to decitabine resulted in a higher remission rate and a clinically meaningful survival extension in these patients with difficult-to-treat disease, without added toxicity.

A modular transcriptome map of mature B cell lymphomas.

BACKGROUND: Germinal center-derived B cell lymphomas are tumors of the lymphoid tissues representing one of the most heterogeneous malignancies. Here we characterize the variety of transcriptomic phenotypes of this disease based on 873 biopsy specimens collected in the German Cancer Aid MMML (Molecular Mechanisms in Malignant Lymphoma) consortium. They include diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), Burkitt's lymphoma, mixed FL/DLBCL lymphomas, primary mediastinal large B cell lymphoma, multiple myeloma, IRF4-rearranged large cell lymphoma, MYC-negative Burkitt-like lymphoma with chr. 11q aberration and mantle cell lymphoma. METHODS: We apply self-organizing map (SOM) machine learning to microarray-derived expression data to generate a holistic view on the transcriptome landscape of lymphomas, to describe the multidimensional nature of gene regulation and to pursue a modular view on co-expression. Expression data were complemented by pathological, genetic and clinical characteristics. RESULTS: We present a transcriptome map of B cell lymphomas that allows visual comparison between the SOM portraits of different lymphoma strata and individual cases. It decomposes into one dozen modules of co-expressed genes related to different functional categories, to genetic defects and to the pathogenesis of lymphomas. On a molecular level, this disease rather forms a continuum of expression states than clearly separated phenotypes. We introduced the concept of combinatorial pattern types (PATs) that stratifies the lymphomas into nine PAT groups and, on a coarser level, into five prominent cancer hallmark types with proliferation, inflammation and stroma signatures. Inflammation signatures in combination with healthy B cell and tonsil characteristics associate with better overall survival rates, while proliferation in combination with inflammation and plasma cell characteristics worsens it. A phenotypic similarity tree is presented that reveals possible progression paths along the transcriptional dimensions. Our analysis provided a novel look on the transition range between FL and DLBCL, on DLBCL with poor prognosis showing expression patterns resembling that of Burkitt's lymphoma and particularly on 'double-hit' MYC and BCL2 transformed lymphomas. CONCLUSIONS: The transcriptome map provides a tool that aggregates, refines and visualizes the data collected in the MMML study and interprets them in the light of previous knowledge to provide orientation and support in current and future studies on lymphomas and on other cancer entities.

A recurrent 11q aberration pattern characterizes a subset of MYC-negative high-grade B-cell lymphomas resembling Burkitt lymphoma.

The genetic hallmark of Burkitt lymphoma (BL) is the t(8;14)(q24;q32) and its variants leading to activation of the MYC oncogene. It is a matter of debate whether true BL without MYC translocation exists. Here, we identified 59 lymphomas concordantly called BL by 2 gene expression classifiers among 753 B-cell lymphomas. Only 2 (3%) of these 59 molecular BL lacked a MYC translocation, which both shared a peculiar pattern of chromosome 11q aberration characterized by interstitial gains including 11q23.2-q23.3 and telomeric losses of 11q24.1-qter. We extended our analysis to 17 MYC-negative high-grade B-cell lymphomas with a similar 11q aberration and showed this aberration to be recurrently associated with morphologic and clinical features of BL. The minimal region of gain was defined by high-level amplifications in 11q23.3 and associated with overexpression of genes including PAFAH1B2 on a transcriptional and protein level. The recurrent region of loss contained a focal homozygous deletion in 11q24.2-q24.3 including the ETS1 gene, which was shown to be mutated in 4 of 16 investigated cases. These findings indicate the existence of a molecularly distinct subset of B-cell lymphomas reminiscent of BL, which is characterized by deregulation of genes in 11q.

Biological characterization of adult MYC-translocation-positive mature B-cell lymphomas other than molecular Burkitt lymphoma.

Chromosomal translocations affecting the MYC oncogene are the biological hallmark of Burkitt lymphomas but also occur in a subset of other mature B-cell lymphomas. If accompanied by a chromosomal break targeting the BCL2 and/or BCL6 oncogene these MYC translocation-positive (MYC(+)) lymphomas are called double-hit lymphomas, otherwise the term single-hit lymphomas is applied. In order to characterize the biological features of these MYC(+) lymphomas other than Burkitt lymphoma we explored, after exclusion of molecular Burkitt lymphoma as defined by gene expression profiling, the molecular, pathological and clinical aspects of 80 MYC-translocation-positive lymphomas (31 single-hit, 46 double-hit and 3 MYC(+)-lymphomas with unknown BCL6 status). Comparison of single-hit and double-hit lymphomas revealed no difference in MYC partner (IG/non-IG), genomic complexity, MYC expression or gene expression profile. Double-hit lymphomas more frequently showed a germinal center B-cell-like gene expression profile and had higher IGH and MYC mutation frequencies. Gene expression profiling revealed 130 differentially expressed genes between BCL6(+)/MYC(+) and BCL2(+)/MYC(+) double-hit lymphomas. BCL2(+)/MYC(+) double-hit lymphomas more frequently showed a germinal center B-like gene expression profile. Analysis of all lymphomas according to MYC partner (IG/non-IG) revealed no substantial differences. In this series of lymphomas, in which immunochemotherapy was administered in only a minority of cases, single-hit and double-hit lymphomas had a similar poor outcome in contrast to the outcome of molecular Burkitt lymphoma and lymphomas without the MYC break. Our data suggest that, after excluding molecular Burkitt lymphoma and pediatric cases, MYC(+) lymphomas are biologically quite homogeneous with single-hit and double-hit lymphomas as well as IG-MYC and non-IG-MYC(+) lymphomas sharing various molecular characteristics.

High resolution copy number analysis of IRF4 translocation-positive diffuse large B-cell and follicular lymphomas.

Translocations affecting chromosome subband 6p25.3 containing the IRF4 gene have been recently described as characteristic alterations in a molecularly distinct subset of germinal center B-cell-derived lymphomas. Secondary changes have yet only been described in few of these lymphomas. Here, we performed array-comparative genomic hybridization and molecular inversion probe microarray analyses on DNA from 12 formalin-fixed paraffin-embedded and two fresh-frozen IRF4 translocation-positive lymphomas, which together with the previously published data on nine cases allowed the extension of copy number analyses to a total of 23 of these lymphomas. All except one case carried chromosomal imbalances, most frequently gains in Xq28, 11q22.3-qter, and 7q32.1-qter and losses in 6q13-16.1, 15q14-22.31, and 17p. No recurrent copy-neutral losses of heterozygosity were observed. TP53 point mutations were detected in three of six cases with loss of 17p. Overall this study unravels a recurrent pattern of secondary genetic alterations in IRF4 translocation-positive lymphomas.

Recurrent deletions of the TNFSF7 and TNFSF9 genes in 19p13.3 in diffuse large B-cell and Burkitt lymphomas.

A single nucleotide polymorphism-chip analysis of 98 cases of aggressive B-cell lymphomas revealed a recurrent deletion at 19p13 in nine of the cases. Six further cases with deletions encompassing this region were found in array-comparative genomic hybridization data of 295 aggressive B-cell lymphomas from a previous study. Three cases even showed a homozygous deletion, suggesting a tumor suppressor gene in the deleted region. Two genes encoding members of the tumor necrosis factor superfamily (TNFSF) were located in the minimally deleted region, that is, TNFSF7 and TNFSF9. As no mutations were found within the coding exons of the remaining alleles in the lymphomas with heterozygous deletions, we speculate that the deletions may mostly function through a haploinsufficiency mechanism. The cases with deletions encompassed both diffuse large B-cell lymphomas and Burkitt lymphomas, and a deletion was also found in a Hodgkin lymphoma cell line. Thus, TNFSF7 and TNFSF9 deletions are recurrent genetic lesions in multiple types of human lymphomas.

Identification of genomic alterations associated with metastasis and cancer specific survival in clear cell renal cell carcinoma.

PURPOSE: We identified regions of DNA copy number changes that are significantly associated with metastasis and clinical outcome in patients with clear cell renal cell carcinoma. MATERIALS AND METHODS: We analyzed 53 primary clear cell renal cell carcinomas, including 31 metastasized and 22 nonmetastasized tumors, by array comparative genomic hybridization with a median resolution of 1 to 1.5 Mbp. To validate copy number aberrations with potential prognostic value we performed fluorescence in situ hybridization analysis using commercially available fluorescent probes. RESULTS: We identified 5 recurrent chromosomal aberrations that were significantly associated with metastasis, including gains of 1q21.3, 12q13.12, 12q13.3q14.1 and 20q11.21q13.2, and loss of 9p21.3p24.1. The most prominent of them with the highest OR for metastatic risk were loss of 9p21.3p24.1, and gains of 1q21.3 and 20q11.21q13.32. Eight alterations involving chromosomes 7, 9, 12, 16 and 20 significantly correlated with shortened cancer specific survival. The lowest p values on Kaplan-Meier analysis showed losses of 9p21.3p24.1 and 9q32q33.1, and gains of 7q36.3 and 20q11.21q13.32. Fluorescence in situ hybridization done in the same cohort for the 4 select regions 1q21.3, 7q36.3, 9p21.3p24.1 and 20q11.21q13.32 clearly confirmed the results of array comparative genomic hybridization. CONCLUSIONS: Data suggest that specific chromosomal alterations in clear cell renal cell carcinoma can be used to predict metastasis and cancer specific survival in patients with clear cell renal cell carcinoma. It seems possible to design a combined fluorescence in situ hybridization assay based on these genetic targets for outcome prediction, which can be used for routine diagnostics.

Translocations activating IRF4 identify a subtype of germinal center-derived B-cell lymphoma affecting predominantly children and young adults.

The prognosis of germinal center-derived B-cell (GCB) lymphomas, including follicular lymphoma and diffuse large-B-cell lymphoma (DLBCL), strongly depends on age. Children have a more favorable outcome than adults. It is not known whether this is because of differences in host characteristics, treatment protocols, or tumor biology, including the presence of chromosomal alterations. By screening for novel IGH translocation partners in pediatric and adult lymphomas, we identified chromosomal translocations juxtaposing the IRF4 oncogene next to one of the immunoglobulin (IG) loci as a novel recurrent aberration in mature B-cell lymphoma. FISH revealed 20 of 427 lymphomas to carry an IG/IRF4-fusion. Those were predominantly GCB-type DLBCL or follicular lymphoma grade 3, shared strong expression of IRF4/MUM1 and BCL6, and lacked PRDM1/BLIMP1 expression and t(14;18)/BCL2 breaks. BCL6 aberrations were common. The gene expression profile of IG/IRF4-positive lymphomas differed from other subtypes of DLBCL. A classifier for IG/IRF4 positivity containing 27 genes allowed accurate prediction. IG/IRF4 positivity was associated with young age and a favorable outcome. Our results suggest IRF4 translocations to be primary alterations in a molecularly defined subset of GCB-derived lymphomas. The probability for this subtype of lymphoma significantly decreases with age, suggesting that diversity in tumor biology might contribute to the age-dependent differences in prognosis of lymphoma.

Detection of genomic aberrations in molecularly defined Burkitt's lymphoma by array-based, high resolution, single nucleotide polymorphism analysis.

BACKGROUND: Knowledge about the genetic lesions that occur in Burkitt's lymphoma, besides the pathognomonic IG-MYC translocations, is limited. DESIGN AND METHODS: Thirty-nine molecularly-defined Burkitt's lymphomas were analyzed with high-resolution single-nucleotide polymorphism chips for genomic imbalances and uniparental disomy. Imbalances were correlated to expression profiles and selected micro-RNA analysis. Translocations affecting the MYC locus were studied by fluorescence in situ hybridization. RESULTS: We detected 528 copy number changes, defining 29 recurrently imbalanced regions. Five hundred and eighteen regions of uniparental disomy were found, but these were rarely recurrent. Combined imbalance mapping and expression profiling revealed a strong correlation between copy number and expression. Several recurrent imbalances affected the MYC pathway: the micro-RNA-supercluster 17-92 was frequently gained and the transcription factor E2F2 was recurrently deleted. Molecular Burkitt's lymphoma lacking MYC translocations showed MYC gains. Amplifications of the polymerase iota gene were associated with increased frequency of positions scored as aberrant. CONCLUSIONS: The present findings suggest that uniparental disomies do not play a major role in the pathogenesis of Burkitt's lymphoma, whereas some genes may contribute to the development of this lymphoma through gene dosage effects. Amplifications of the polymerase iota gene may be functionally linked with increased genomic alterations in Burkitt's lymphoma. The pattern and rarity of chromosomal changes detectable, even at the high resolution employed here, together with aberrations of genes regulating MYC activity, support the hypothesis that deregulation of the MYC pathway is the major force driving the pathogenesis of Burkitt's lymphoma, but show that this deregulation is more complex than previously known.

Microarray-based genomic profiling reveals novel genomic aberrations in follicular lymphoma which associate with patient survival and gene expression status.

Follicular lymphoma (FL) is characterized by a large number of chromosomal aberrations. However, their exact genomic extension and involved target genes remain to be determined. For this purpose, we used array-based intermediate-high resolution genomic profiling in combination with Affymetrix gene expression analysis. Tumor specimens from 128 FL patients were analyzed for the presence of genomic aberrations and the results were correlated to clinical data sets and mRNA expression levels. In 114 (89%) of the 128 analyzed cases, a total of 688 genomic aberrations (384 gains/amplifications and 304 losses) were detected. Frequent genomic aberrations were: -1p36 (18%), +2p15 (24%), -3q (14%), -6q (25%), +7p (19%), +7q (23%), +8q (14%), -9p (16%), -11q (15%), +12q (20%), -13q (11%), -17p (16%), +18p (18%), and +18q (28%). Critical segments of these imbalances were delineated to genomic fragments with a minimum size down to 0.2 Mb. By comparison of these with mRNA gene expression data, putative candidate genes were identified. Moreover, we found that deletions affecting the tumor suppressor gene CDKN2A/B on 9p21 were detected in nontransformed FL grade I-II. For this aberration as well as for -6q25 and -6q26, an association with inferior survival was observed.

New insights into the biology and origin of mature aggressive B-cell lymphomas by combined epigenomic, genomic, and transcriptional profiling.

Lymphomas are assumed to originate at different stages of lymphocyte development through chromosomal aberrations. Thus, different lymphomas resemble lymphocytes at distinct differentiation stages and show characteristic morphologic, genetic, and transcriptional features. Here, we have performed a microarray-based DNA methylation profiling of 83 mature aggressive B-cell non-Hodgkin lymphomas (maB-NHLs) characterized for their morphologic, genetic, and transcriptional features, including molecular Burkitt lymphomas and diffuse large B-cell lymphomas. Hierarchic clustering indicated that methylation patterns in maB-NHLs were not strictly associated with morphologic, genetic, or transcriptional features. By supervised analyses, we identified 56 genes de novo methylated in all lymphoma subtypes studied and 22 methylated in a lymphoma subtype-specific manner. Remarkably, the group of genes de novo methylated in all lymphoma subtypes was significantly enriched for polycomb targets in embryonic stem cells. De novo methylated genes in all maB-NHLs studied were expressed at low levels in lymphomas and normal hematopoietic tissues but not in nonhematopoietic tissues. These findings, especially the enrichment for polycomb targets in stem cells, indicate that maB-NHLs with different morphologic, genetic, and transcriptional background share a similar stem cell-like epigenetic pattern. This suggests that maB-NHLs originate from cells with stem cell features or that stemness was acquired during lymphomagenesis by epigenetic remodeling.

Molecular profiling of pediatric mature B-cell lymphoma treated in population-based prospective clinical trials.

The spectrum of entities, the therapeutic strategy, and the outcome of mature aggressive B-cell non-Hodgkin lymphomas (maB-NHLs) differs between children and adolescents on the one hand and adult patients on the other. Whereas adult maB-NHLs have been studied in detail, data on molecular profiling of pediatric maB-NHLs are hitherto lacking. We analyzed 65 cases of maB-NHL from patients up to 18 years of age by gene expression profiling, matrix comparative genomic hybridization (CGH), fluorescent in situ hybridization (FISH), and immunohistochemistry. The majority of the analyzed pediatric patients were treated within prospective trials (n = 49). We compared this group to a series of 182 previously published cases of adult maB-NHL. Gene expression profiling reclassified 31% of morphologically defined diffuse large B-cell lymphomas as molecular Burkitt lymphoma (mBL). The subgroups obtained by molecular reclassification did not show any difference in outcome in children treated with the NHL-Berlin-Frankfurt-Muenster (BFM) protocols. No differences were detectable between pediatric and adult mBL with regard to gene expression or chromosomal imbalances. This is the first report on molecular profiling of pediatric B-NHL showing mBL to be much more prominent in children than suggested by morphologic assessment. Based on molecular profiling mBL is a molecularly homogeneous disease across children and adults.

Gain of chromosome region 18q21 including the MALT1 gene is associated with the activated B-cell-like gene expression subtype and increased BCL2 gene dosage and protein expression in diffuse large B-cell lymphoma.

BACKGROUND: The aim of this study was to determine the impact of a gain of the MALT1 gene on gene expression and clinical parameters in diffuse large B-cell lymphoma. DESIGN AND METHODS: We analyzed 116 cases of diffuse large B-cell lymphoma by fluorescence in situ hybridization, array-based comparative genomic hybridization, and transcriptional profiling. RESULTS: A gain of 18q21 including MALT1 was detected in 44 cases (38%) and was accompanied by a gain of BCL2 in 43 cases. All cases with a 18q21/MALT1 gain showed BCL2 protein whereas 79% in the group without a 18q21/MALT1 gain did so (p<0.001). Cases with 18q21/MALT1 gain more frequently showed an activated B-cell-like (ABC) gene expression signature (65%) than a germinal center B-cell-like (GCB) one (23%) (p<0.001). Ninety-eight genes including MALT1, BCL2, and some selected nuclear factor-kappaB target genes were differentially expressed between the two genetic groups of diffuse large B-cell lymphoma. By global testing of each chromosome, we identified 33 genes, all located on chromosome 18q, which were differentially expressed between the two genetic groups independently of the ABC/GCB status. In multivariate analysis, the 18q21/MALT1 status represented an independent negative prognostic factor for overall survival (p=0.03). CONCLUSIONS: In diffuse large B-cell lymphoma, gain of 18q21 including MALT1 is significantly associated with differential expression of genes located on 18q, the ABC gene expression subtype, increased BCL2 gene and protein expression and might indicate an unfavorable prognosis.

Matrix-comparative genomic hybridization from multicenter formalin-fixed paraffin-embedded colorectal cancer tissue blocks.

BACKGROUND: The identification of genomic signatures of colorectal cancer for risk stratification requires the study of large series of cancer patients with an extensive clinical follow-up. Multicentric clinical studies represent an ideal source of well documented archived material for this type of analyses. METHODS: To verify if this material is technically suitable to perform matrix-CGH, we performed a pilot study using macrodissected 29 formalin-fixed, paraffin-embedded tissue samples collected within the framework of the EORTC-GI/PETACC-2 trial for colorectal cancer. The scientific aim was to identify prognostic genomic signatures differentiating locally restricted (UICC stages II-III) from systemically advanced (UICC stage IV) colorectal tumours. RESULTS: The majority of archived tissue samples collected in the different centers was suitable to perform matrix-CGH. 5/7 advanced tumours displayed 13q-gain and 18q-loss. In locally restricted tumours, only 6/12 tumours showed a gain on 13q and 7/12 tumours showed a loss on 18q. Interphase-FISH and high-resolution array-mapping of the gain on 13q confirmed the validity of the array-data and narrowed the chromosomal interval containing potential oncogenes. CONCLUSION: Archival, paraffin-embedded tissue samples collected in multicentric clinical trials are suitable for matrix-CGH analyses and allow the identification of prognostic signatures and aberrations harbouring potential new oncogenes.

Recurrent FGFR1 amplification and high FGFR1 protein expression in oral squamous cell carcinoma (OSCC).

Chromosomal aberrations are known to have an impact on the initiation and progression of oral squamous cell carcinoma (OSCC), but individual genes involved in OSCC pathogenesis are poorly described. To elucidate the molecular events underlying oral carcinogenesis, a set of primary OSCC were screened for distinct genetic imbalances by means of array-based comparative genomic hybridisation. For this, a DNA array was used containing 812 genomic targets including oncogenes, tumour-suppressor genes and chromosomal regions frequently altered in human neoplasms. The most frequent aberrations were amplification of MYC, EGFR, CCND1 and PIK3CA, whereas deletions affected TRAILR1 and ATM. Furthermore, a distinct high-level amplification of the fibroblast growth factor receptor 1 (FGFR1) locus was detected in two cases. Detailed FISH analysis on OSCC tissue microarray sections revealed amplification prevalence for FGFR1 of 17.4% (16/92). Furthermore, FGFR1 protein analysis by immunohistochemistry on a TMA containing 178 OSCC found a high FGFR1 expression in tumours of early t-stadium and UICC stage (T1/2 vs. T3/4: p=0.002; SI-II vs. S III-IV: p=0.048). Our results indicate that an increase in FGFR1 expression contributes to oral carcinogenesis at an early stage of development.

Disclosure of candidate genes in acute myeloid leukemia with complex karyotypes using microarray-based molecular characterization.

PURPOSE: To identify novel genomic regions of interest in acute myeloid leukemia (AML) with complex karyotypes, we applied comparative genomic hybridization to microarrays (array-CGH), allowing high-resolution genome-wide screening of genomic imbalances. PATIENTS AND METHODS: Sixty AML cases with complex karyotypes were analyzed using array-CGH; parallel analysis of gene expression was performed in a subset of cases. RESULTS: Genomic losses were found more frequently than gains. The most frequent losses affected 5q (77%), 17p (55%), and 7q (45%), and the most frequent genomic gains 11q (40%) and 8q (38%). Critical segments could be delineated to genomic fragments of only 0.8 to a few megabase-pairs of DNA. In lost/gained regions, gene expression profiling detected a gene dosage effect with significant lower/higher average gene expression levels across the genes located in the respective regions. Furthermore, high-level DNA amplifications were identified in several regions: 11q23.3-q24.1 (n = 7), 21q22 (n = 6), 11q23.3 (n = 5), 13q12 (n = 3), 8q24 (n = 3), 9p24 (n = 2), 12p13 (n = 2), and 20q11 (n = 2). Parallel analysis of gene expression in critical amplicons displayed overexpressed candidate genes (eg, C8FW and MYC in 8q24). CONCLUSION: In conclusion, a large spectrum of genomic imbalances, including novel recurring changes in AML with complex karyotypes, was identified using array-CGH. In addition, the combined analysis of array-CGH data with gene expression profiles allowed the detection of candidate genes involved in the pathogenesis of AML.

A biologic definition of Burkitt's lymphoma from transcriptional and genomic profiling.

BACKGROUND: The distinction between Burkitt's lymphoma and diffuse large-B-cell lymphoma is unclear. We used transcriptional and genomic profiling to define Burkitt's lymphoma more precisely and to distinguish subgroups in other types of mature aggressive B-cell lymphomas. METHODS: We performed gene-expression profiling using Affymetrix U133A GeneChips with RNA from 220 mature aggressive B-cell lymphomas, including a core group of 8 Burkitt's lymphomas that met all World Health Organization (WHO) criteria. A molecular signature for Burkitt's lymphoma was generated, and chromosomal abnormalities were detected with interphase fluorescence in situ hybridization and array-based comparative genomic hybridization. RESULTS: We used the molecular signature for Burkitt's lymphoma to identify 44 cases: 11 had the morphologic features of diffuse large-B-cell lymphomas, 4 were unclassifiable mature aggressive B-cell lymphomas, and 29 had a classic or atypical Burkitt's morphologic appearance. Also, five did not have a detectable IG-myc Burkitt's translocation, whereas the others contained an IG-myc fusion, mostly in simple karyotypes. Of the 176 lymphomas without the molecular signature for Burkitt's lymphoma, 155 were diffuse large-B-cell lymphomas. Of these 155 cases, 21 percent had a chromosomal breakpoint at the myc locus associated with complex chromosomal changes and an unfavorable clinical course. CONCLUSIONS: Our molecular definition of Burkitt's lymphoma clarifies and extends the spectrum of the WHO criteria for Burkitt's lymphoma. In mature aggressive B-cell lymphomas without a gene signature for Burkitt's lymphoma, chromosomal breakpoints at the myc locus were associated with an adverse clinical outcome.

Antagonizing inactivated tumor suppressor genes and activated oncogenes by a versatile transgenesis system: application in mantle cell lymphoma.

A broad range of malignant diseases, such as mantle cell lymphoma (MCL), is associated with complex genomic alterations, demanding multimodal functional testing of candidate genes. To assess such candidate disease genes, we have developed a bidirectional targeted transgenesis tool, which allows well-controlled modulation of individual gene activities within a cellular MCL system. The engineered versatile transgenesis system permits functional analysis of virtually any candidate gene: for tumor suppressor genes by complementation via integration of respective genomic DNA or for oncogenes by inactivation via integrated shRNA coding plasmids. Complementation by genomic DNA ensures wild-type (WT) regulated gene expression, whereas genomic integration of shRNA coding inserts by an advanced RNAi-strategy mediates specific knock-down of gene expression. Site-specific genomic integration of an unmodified BAC, which contains the CDKN2A/B genes absent in the MCL model system, restored CDKN2A/B expression resulting in the inhibition of cell proliferation. CCND1, strongly overexpressed in the model system, was down-regulated via shRNA expression, again inhibiting proliferation. Notably, the presented site-specific shRNA-strategy circumvents interference by IFN-response induced when using other RNAi gene knock-down methods. In conclusion, we here demonstrate that adequate restoration of a range of different gene activities yields in a desired antiproliferative effect in MCL-derived cells. By antagonizing inactivated tumor suppressor genes or activated oncogenes, the presented approach can be readily used for the functional analysis of a broad range of disease-related genetic defects.

Molecular classification of human gliomas using matrix-based comparative genomic hybridization.

Gliomas are the most frequent primary brain tumors and comprise a group of morphologically, biologically and clinically heterogeneous neoplasms. The different glioma types are associated with distinct genetic aberrations, which may provide useful information for tumor classification as well as prediction of prognosis and response to therapy. To facilitate the molecular classification of gliomas, we established a genomic microarray that consists of bacterial artificial chromosome (BAC) and P1-derived artificial chromosome (PAC) clones representing tumor suppressor genes, proto-oncogenes and chromosomal regions frequently gained or lost in gliomas. In addition, reference clones distributed evenly throughout the genome in approximately 15 Mbp intervals were spotted on the microarray. These customized microarrays were used for matrix-based comparative genomic hybridization (matrix CGH) analysis of 70 gliomas. Matrix CGH findings were validated by molecular genetic analyses of candidate genes, loss of heterozygosity studies and chromosomal CGH. Our results indicate that matrix CGH allows for the sensitive and specific detection of gene amplifications as well as low-level copy number gains and losses in clinical glioma samples. Furthermore, molecular classification based on matrix CGH data closely paralleled histological classification and was able to distinguish with few exceptions between diffuse astrocytomas and oligodendrogliomas, anaplastic astrocytomas and anaplastic oligodendrogliomas, anaplastic oligodendrogliomas and glioblastomas, as well as primary and secondary glioblastomas. Thus, matrix CGH is a powerful technique that allows for an automated genomic profiling of gliomas and represents a promising new tool for their molecular classification.

Candidate genes in breast cancer revealed by microarray-based comparative genomic hybridization of archived tissue.

Genomic imbalances in 31 formalin-fixed and paraffin-embedded primary tumors of advanced breast cancer were analyzed by microarray-based comparative genomic hybridization (matrix-CGH). A DNA chip was designed comprising 422 mapped genomic sequences including 47 proto-oncogenes, 15 tumor suppressor genes, as well as frequently imbalanced chromosomal regions. Analysis of the data was challenging due to the impaired quality of DNA prepared from paraffin-embedded samples. Nevertheless, using a method for the statistical evaluation of the balanced state for each individual experiment, we were able to reveal imbalances with high significance, which were in good concordance with previous data collected by chromosomal CGH from the same patients. Owing to the improved resolution of matrix-CGH, genomic imbalances could be narrowed down to the level of individual bacterial artificial chromosome and P1-derived artificial chromosome clones. On average 37 gains and 13 losses per tumor cell genome were scored. Gains in more than 30% of the cases were found on 1p, 1q, 6p, 7p, 8q, 9q, 11q, 12q, 17p, 17q, 20q, and 22q, and losses on 6q, 9p, 11q, and 17p. Of the 51 chromosomal regions found amplified by matrix-CGH, only 12 had been identified by chromosomal CGH. Within these 51 amplicons, genome database information defined 112 candidate genes, 44 of which were validated by either PCR amplification of sequence tag sites or DNA sequence analysis.