scholarly journals Genomic and Expression Profiling of Hairy Cell Leukemia Revealed Multiple Mechanisms of NFkB Activation

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3526-3526 ◽  
Author(s):  
Stefan Nagel ◽  
Stefan Ehrentraut ◽  
Corinna Meyer ◽  
Maren Kaufmann ◽  
Hans G Drexler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
B Cell ◽  
Cell Lines ◽  
Expression Profiling ◽  
Braf V600e ◽  
Hairy Cell ◽  
Cell Leukemia ◽  
Braf Mutations ◽  
Nfkb Pathway

Abstract Hairy cell leukemia (HCL) is a rare chronic B-cell lymphoproliferative disorder where the malignant B-cells manifest a “hairy” appearance under the microscope. Recent studies have identified BRAF V600E mutations in most HCL patients, highlighting this abnormality as a molecular hallmark for this disease. However, mutated BRAF occurs widely – already described in several solid tumors, including melanoma, thyroid and colorectal carcinomas, indicating that BRAF V600E is not pathognomonic in HCL. Cell lines originating from HCL patients lack BRAF mutations but retain the typical piliferous morphology and the appropriate HCL immunophenotype (CD19, CD11c, CD103, CD25, CD123), thus constituting tools for identifying alternative mechanisms of leukemogenesis in this disease entity. Genomic aberrations in hematopoietic tumors recurrently target loci bearing genes involved in malignant transformation. These genes may include both candidate biomarkers and potential therapeutic targets. To identify such genes in HCL we here combined genomic profiling and gene expression quantification of a well characterized HCL cell line containing several chromosomal aberrations. The expression levels of genomically targeted genes were compared to HCL control cell lines, identifying 91 deregulated genes. Gene set enrichment analysis of which indicated apoptosis, cell cycle regulation and DNA damage response (DDR) as altered processes in HCL. Accordingly, REL (NFkB and apoptosis), CDK6 and BRAF (cell cycle), ATM and CUTL1 (DDR) comprised prominent target genes overexpressed in this cell line. The same genes were found to be conspicuously expressed in HCL patient samples in silico (Fernandez et al., 2010; Gene Expression Omnibus GSE16455), supporting their clinical significance. Treatments of HCL cell lines for particular siRNA-mediated gene knockdowns and with selective pharmacological inhibitors helped to reveal a regulatory network highlighting NFkB at a central position. Consistently, focused analysis of expression profiling data of several cell lines supported elevated NFkB-pathway activity in HCL and ABC-DLBCL when compared to GC-DLBCL. In conclusion, we identified deregulated genes and multiple mechanisms which contribute to aberrantly activated NFkB-pathway in HCL. Therefore, NFkB may represent a B-cell specific hallmark of HCL and a promising novel therapeutic target most notably in patients lacking BRAF mutations in this entity. Disclosures No relevant conflicts of interest to declare.

scholarly journals Gene Expression Profiling of Hairy Cell Leukemia Reveals a Phenotype Related to Memory B Cells with Altered Expression of Chemokine and Adhesion Receptors

2004 ◽  
Vol 199 (1) ◽  
pp. 59-68 ◽  
Author(s):  
Katia Basso ◽  
Arcangelo Liso ◽  
Enrico Tiacci ◽  
Roberta Benedetti ◽  
Alessandro Pulsoni ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
B Cell ◽  
Gene Expression Profiling ◽  
Hairy Cell Leukemia ◽  
Expression Profiling ◽  
Memory B Cells ◽  
Memory Cells ◽  
Hairy Cell ◽  
Cell Leukemia

Hairy cell leukemia (HCL) is a chronic B cell malignancy characterized by the diffuse infiltration of bone marrow and spleen by cells displaying a typical “hairy” morphology. However, the nature of the HCL phenotype and its relationship to normal B cells and to other lymphoma subtypes remains unclear. Using gene expression profiling, we show here that HCL displays a homogeneous pattern of gene expression, which is clearly distinct from that of other B cell non-Hodgkin lymphomas. Comparison with the gene expression profiles of purified normal B cell subpopulations, including germinal center (GC), pre-GC (naive), and post-GC (memory) B cells, shows that HCL cells are more related to memory cells, suggesting a derivation from this B cell population. Notably, when compared with memory cells, HCL cells displayed a remarkable conservation in proliferation, apoptosis, and DNA metabolism programs, whereas they appeared significantly altered in the expression of genes controlling cell adhesion and response to chemokines. Finally, these analyses have identified several genes that are specifically expressed in HCL and whose expression was confirmed at the protein level by immunocytochemical analysis of primary HCL cases. These results have biological implications relevant to the pathogenesis of this malignancy as well as clinical implications for its diagnosis and therapy.

scholarly journals Constant Activation of the RAF-MEK-ERK Pathway As a Diagnostic and Therapeutic Target in Hairy Cell Leukemia.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2657-2657
Author(s):  
Enrico Tiacci ◽  
Gianluca Schiavoni ◽  
Maria Paola Martelli ◽  
Emanuela Boveri ◽  
Roberta Pacini ◽  
...  
Keyword(s):  
B Cell ◽  
Therapeutic Target ◽  
Hairy Cell Leukemia ◽  
Braf V600e Mutation ◽  
Braf V600e ◽  
Erk Pathway ◽  
Clinical Use ◽  
Hairy Cell ◽  
Cell Leukemia ◽  
Braf Mutations

Abstract Abstract 2657 The BRAF-V600E mutation defines genetically hairy cell leukemia (HCL) among B-cell leukemias and lymhphomas. In solid tumors, BRAF-V600E is known to aberrantly activate the oncogenic MEK-ERK pathway, and targeted BRAF and/or MEK inhibitors have shown remarkable efficacy in clinical trials of melanoma patients. However, the MEK-ERK pathway status in HCL has not been thoroughly investigated so far. Therefore, as a read-out of MEK-ERK pathway activation, we assessed phospho-ERK expression in 37 HCL patients using immunohistochemistry on routine biopsies and/or Western blotting on purified leukemic cells. Beside confirming the constant presence of BRAF-V600E in all patients, we documented ubiquitous phospho-ERK expression in HCL. Conversely, all 44 HCL-like cases in parallel studied (40 splenic marginal zone lymphoma, 2 HCL-variant and 2 splenic lymphoma/leukemia unclassifiable) were devoid of BRAF-V600E and none expressed phospho-ERK. Lack of phospho-ERK expression was also documented in two exceptionally rare cases of non-HCL CD5-negative B-cell lymphoproliferative disorders not otherwise specifiable that were previously described to harbour the BRAF-V600E mutation on allele-specific PCR (Arcaini et al, Blood 2012;119:188–191), pointing to the presence of this mutation in only a small part of the leukemic clone in these cases. Our findings support the use of phospho-ERK immunohistochemistry in the differential diagnosis between HCL and HCL-like neoplasms and establish the MEK-ERK pathway as a rational therapeutic target in HCL. Disclosures: Tiacci: Not applicable: Dr. Tiacci filed a patent for the clinical use of BRAF mutations as biomarkers of HCL. Other. Inghirami:OncoEthix SA: Research Funding. Falini:Not applicable: Dr. Falini filed a patent for the clinical use of BRAF mutations as biomarkers of HCL. Other.

scholarly journals BRAF mutation in hairy cell leukemia

2014 ◽  
Author(s):  
Ahmad Ahmadzadeh ◽  
Saeid Shahrabi ◽  
Kaveh Jaseb ◽  
Fatemeh Norozi ◽  
Mohammad Shahjahani ◽  
...  
Keyword(s):  
B Cell ◽  
Hairy Cell Leukemia ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Braf V600e ◽  
Common Mutation ◽  
Hairy Cell ◽  
Cell Leukemia ◽  
Mitogen Activated Protein ◽  
Almost All

BRAF is a serine/threonine kinase with a regulatory role in the mitogen-activated protein kinase (MAPK) signaling pathway. A mutation in the RAF gene, especially in BRAF protein, leads to an increased stimulation of this cascade, causing uncontrolled cell division and development of malignancy. Several mutations have been observed in the gene coding for this protein in a variety of human malignancies, including hairy cell leukemia (HCL). BRAF V600E is the most common mutation reported in exon15 of BRAF, which is observed in almost all cases of classic HCL, but it is negative in other B-cell malignancies, including the HCL variant. Therefore it can be used as a marker to differentiate between these B-cell disorders. We also discuss the interaction between miRNAs and signaling pathways, including MAPK, in HCL. When this mutation is present, the use of BRAF protein inhibitors may represent an effective treatment. In this review we have evaluated the role of the mutation of the BRAF gene in the pathogenesis and progression of HCL.

scholarly journals Microarray gene expression profiling in colorectal (HCT116) and hepatocellular (HepG2) carcinoma cell lines treated withMelicope ptelefolialeaf extract reveals transcriptome profiles exhibiting anticancer activity

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5203 ◽  
Author(s):  
Mohammad Faujul Kabir ◽  
Johari Mohd Ali ◽  
Onn Haji Hashim
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Dna Replication ◽  
Cell Lines ◽  
Microarray Data ◽  
Expression Profiling ◽  
Cell Cycle Progression ◽  
Anticancer Activities ◽  
Microarray Gene Expression ◽  
Cycle Progression

BackgroundWe have previously reported anticancer activities ofMelicope ptelefolia(MP) leaf extracts on four different cancer cell lines. However, the underlying mechanisms of actions have yet to be deciphered. In the present study, the anticancer activity of MP hexane extract (MP-HX) on colorectal (HCT116) and hepatocellular carcinoma (HepG2) cell lines was characterized through microarray gene expression profiling.MethodsHCT116 and HepG2 cells were treated with MP-HX for 24 hr. Total RNA was extracted from the cells and used for transcriptome profiling using Applied Biosystem GeneChip™ Human Gene 2.0 ST Array. Gene expression data was analysed using an Applied Biosystems Expression Console and Transcriptome Analysis Console software. Pathway enrichment analyses was performed using Ingenuity Pathway Analysis (IPA) software. The microarray data was validated by profiling the expression of 17 genes through quantitative reverse transcription PCR (RT-qPCR).ResultsMP-HX induced differential expression of 1,290 and 1,325 genes in HCT116 and HepG2 cells, respectively (microarray data fold change, MA_FC ≥ ±2.0). The direction of gene expression change for the 17 genes assayed through RT-qPCR agree with the microarray data. In both cell lines, MP-HX modulated the expression of many genes in directions that support antiproliferative activity. IPA software analyses revealed MP-HX modulated canonical pathways, networks and biological processes that are associated with cell cycle, DNA replication, cellular growth and cell proliferation. In both cell lines, upregulation of genes which promote apoptosis, cell cycle arrest and growth inhibition were observed, while genes that are typically overexpressed in diverse human cancers or those that promoted cell cycle progression, DNA replication and cellular proliferation were downregulated. Some of the genes upregulated by MP-HX include pro-apoptotic genes (DDIT3, BBC3, JUN), cell cycle arresting (CDKN1A, CDKN2B), growth arrest/repair (TP53, GADD45A) and metastasis suppression (NDRG1). MP-HX downregulated the expression of genes that could promote anti-apoptotic effect, cell cycle progression, tumor development and progression, which include BIRC5, CCNA2, CCNB1, CCNB2, CCNE2, CDK1/2/6, GINS2, HELLS, MCM2/10 PLK1, RRM2 and SKP2. It is interesting to note that all six top-ranked genes proposed to be cancer-associated (PLK1, MCM2, MCM3, MCM7, MCM10 and SKP2) were downregulated by MP-HX in both cell lines.DiscussionThe present study showed that the anticancer activities of MP-HX are exerted through its actions on genes regulating apoptosis, cell proliferation, DNA replication and cell cycle progression. These findings further project the potential use of MP as a nutraceutical agent for cancer therapeutics.

scholarly journals Genomics of Hairy Cell Leukemia

2017 ◽  
Vol 35 (9) ◽  
pp. 1002-1010 ◽  
Author(s):  
Enrico Tiacci ◽  
Valentina Pettirossi ◽  
Gianluca Schiavoni ◽  
Brunangelo Falini
Keyword(s):  
B Cell ◽  
Hairy Cell Leukemia ◽  
Ex Vivo ◽  
Braf Inhibitor ◽  
Braf V600e ◽  
Leukemic Cells ◽  
Splenic Marginal Zone Lymphoma ◽  
Hairy Cell ◽  
Cell Leukemia ◽  
Purine Analogs

Hairy cell leukemia (HCL) is a chronic mature B-cell neoplasm with unique clinicopathologic features and an initial exquisite sensitivity to chemotherapy with purine analogs; however, the disease relapses, often repeatedly. The enigmatic pathogenesis of HCL was recently clarified by the discovery of its underlying genetic cause, the BRAF-V600E kinase-activating mutation, which is somatically and clonally present in almost all patients through the entire disease spectrum and clinical course. By aberrantly activating the RAF-MEK-ERK signaling pathway, BRAF-V600E shapes key biologic features of HCL, including its specific expression signature, hairy morphology, and antiapoptotic behavior. Accompanying mutations of the KLF2 transcription factor or the CDKN1B/p27 cell cycle inhibitor are recurrent in 16% of patients with HCL and likely cooperate with BRAF-V600E in HCL pathogenesis. Conversely, BRAF-V600E is absent in other B-cell neoplasms, including mimickers of HCL that require different treatments (eg, HCL-variant and splenic marginal zone lymphoma). Thus, testing for BRAF-V600E allows for a genetics-based differential diagnosis between HCL and HCL-like tumors, even noninvasively in routine blood samples. BRAF-V600E also represents a new therapeutic target. Patients’ leukemic cells exposed ex vivo to BRAF inhibitors are spoiled of their HCL identity and then undergo apoptosis. In clinical trials of patients with HCL who have experienced multiple relapses after purine analogs or who are refractory to purine analogs, a short course of the oral BRAF inhibitor vemurafenib produced an almost 100% response rate, including complete remission rates of 35% to 42%, without myelotoxicity. To further improve on these results, it will be important to clarify the mechanisms of incomplete leukemic cell eradication by vemurafenib and to explore chemotherapy-free combinations of a BRAF inhibitor with other targeted agents (eg, a MEK inhibitor and/or an anti-CD20 monoclonal antibody).

scholarly journals Both variant and IGHV4-34–expressing hairy cell leukemia lack the BRAF V600E mutation

Blood ◽  
2012 ◽  
Vol 119 (14) ◽  
pp. 3330-3332 ◽  
Author(s):  
Liqiang Xi ◽  
Evgeny Arons ◽  
Winnifred Navarro ◽  
Katherine R. Calvo ◽  
Maryalice Stetler-Stevenson ◽  
...  
Keyword(s):  
B Cell ◽  
Hairy Cell Leukemia ◽  
Poor Prognosis ◽  
Braf V600e Mutation ◽  
Braf V600e ◽  
Hairy Cell ◽  
Cell Leukemia ◽  
Wild Type ◽  
Ighv Gene ◽  
Gene Usage

Abstract Recently, the BRAF V600E mutation was reported in all cases of hairy cell leukemia (HCL) but not in other peripheral B-cell neoplasms. We wished to confirm these results and assess BRAF status in well-characterized cases of HCL associated with poor prognosis, including the immunophenotypically defined HCL variant (HCLv) and HCL expressing the IGHV4-34 immunoglobulin rearrangement. Fifty-three classic HCL (HCLc) and 16 HCLv cases were analyzed for BRAF, including 5 HCLc and 8 HCLv expressing IGHV4-34. BRAF was mutated in 42 (79%) HCLc, but wild-type in 11 (21%) HCLc and 16 (100%) HCLv. All 13 IGHV4-34+ HCLs were wild-type. IGHV gene usage in the 11 HCLc BRAF wild-type cases included 5 IGHV4-34, 5 other, and 1 unknown. Our results suggest that HCLv and IGHV4-34+ HCLs have a different pathogenesis than HCLc and that a significant minority of other HCLc are also wild-type for BRAF V600.

Comprehensive Analysis of Homeobox Gene Expression in Hodgkin Lymphoma Cell Lines Reveals Similarities to Prostate Carcinoma.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 966-966
Author(s):  
Stefan Nagel ◽  
Christof Burek ◽  
Hilmar Quentmeier ◽  
Corinna Meyer ◽  
Andreas Rosenwald ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
B Cell ◽  
Hodgkin Lymphoma ◽  
Cell Lines ◽  
Prostate Carcinoma ◽  
Homeobox Genes ◽  
Homeobox Gene ◽  
Cell Cycle Regulators ◽  
Rt Pcr

Abstract Homeobox genes code for transcription factors with essential regulatory impact on cellular processes during embryogenesis and in the adult. Increasingly, members of the circa 200 gene strong family are emerging as major oncogenic players, prompting our investigation into possible homeobox gene dysregulation in Hodgkin lymphoma (HL) in which no recurrent oncogene involvement has been known. Accordingly, we screened 6 well characterized HL cell lines (HDLM-2, KM-H2, L-1236, L-428, L-540, SUP-HD1) and 3 non-Hodgkin lymphoma (NHL) cell lines (RC-K8, RI-1, SC-1) for homeobox gene expression using Affymetrix U133-2.0 whole-genome oligonucleotide microarrays. Of 15 candidate genes thus shown to reveal HL-specific expression patterns, 5 homeobox genes were shortlisted as potentially key dysregulatory targets in HL after additional RT-PCR expression analysis relative to controls. While 3/5 homeobox genes were upregulated in HL (HOXB9, HOXC8, HLXB9), 2/5 were downregulated (BOB1, PAX5). Furthermore, cloning and sequencing RT-PCR products obtained with degenerate primers recognizing conserved homeobox motifs confirmed the predominant expression of HOXB9 in HL cells. However, fluorescence in situ hybridization (FISH) analysis of the HOXB locus (at 17q21) revealed no cytogenetic aberrations, indicating that its activation is conducted non-chromosomally in HL cells. Surprisingly, known target genes of HOXB9 and HOXC8 remained unperturbed, implying novel downstream effector pathways in HL cells. Antisense oligos directed against HOXB9 and forced expression experiments using cloned full length HOXB9 cDNA indicated its involvement in both proliferation and apoptosis. Cell cycle regulators BTG1, BTG2 and GEMININ have been described to interact with HOXB9 and may represent potential targets deserving investigation. We recently showed that HLXB9 promotes IL6 expression in HL cells in response to a constitutively active PI3K signalling pathway therein (Nagel et al., Leukemia19, 841–6, 2005). Our most recent data indicate that HLXB9 is also expressed in various NHL cell lines including anaplastic, diffuse and mediastinal large cell as well as follicular B-cell lymphomas while expression is notably absent from Burkitt, mantle cell and natural killer T-cell lymphomas reflecting their pathologic classification. Intriguingly, our data highlight unexpected similarities between HL and prostate cancer cells which together uniquely overexpress HOXB9, HOXC8 and HLXB9 (or its close homolog GBX2). Additional genes expressed in prostate carcinoma (HOXB13, PRAC1, PRAC2) were detected in two HL cell lines (KM-H2 and L-428) suggesting further parallels may be revealed. Detection of downregulated B-cell differentiation factors BOB1 and PAX5 in our panel of HL cell lines validated this approach. Both factors were previously implicated in oncogenesis of HL lacking IGH rearrangements and other key B-cell characteristics. In summary, we identified a unique homeobox gene expression pattern involving HOXB9, HOXB13, HOXC8 and HLXB9 in HL cell lines resembling that of prostate carcinoma cells. Overexpressed HOXB9 contributes to proliferation and protects against apoptosis in HL cells potentially via interacting with cell cycle regulators BTG1/2 and/or GEMININ.

Gene Expression Profiling Reveals a Crucial Role for C/EBPbeta in Proliferation Pathways of ALK+ ALCL Cell Lines

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2818-2818
Author(s):  
Irina Bonzheim ◽  
Martin Irmler ◽  
Natasa Anastasov ◽  
Margit Klier ◽  
Johannes Beckers ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Statistical Analysis ◽  
Gene Expression Profiling ◽  
Cell Lines ◽  
Expression Profiling ◽  
Leucine Zipper ◽  
Cellular Proliferation ◽  
Kinase Activity ◽  
Large Cell

Abstract Introduction: ALK+ anaplastic large cell lymphomas (ALCL) overexpress C/EBPβ, as a consequence of NPM-ALK kinase activity. C/EBPβ is a leucine zipper transcription factor, which plays a major role in cellular differentiation, inflammation, proliferation and metabolism control. To determine the role of C/EBPβ in ALK+ ALCL transformation, and to identify its downstream targets, a highly specific C/EBPβ-shRNA was used to knockdown C/EBPβ. The consequences of C/EBPβ gene-silencing were analyzed by gene expression profiling. Materials and Methods: Four ALK+ ALCL cell lines, SUDHL-1, Kijk, Karpas 299 and SUP-M2 were transfected with lentivirus containing the C/EBPβ shRNA or the vector without shRNA in triplicates. Western Blot analysis and qRT-PCR were performed to quantify the knockdown effect. At day three after infection, RNA was extracted and used for Gene Chip expression analysis (Affymetrix). Using Anova software for statistical analysis, we identified genes, which were regulated in all four cell lines. The effect of C/EBPβ knockdown on proliferation, cell cycle, and viability was analyzed by MTT assay and FACS analysis. Results: In all four ALK+ ALCL, efficient C/EBPβ knockdown resulted in profound growth retardation (up to 84%) compared to control cells after 6 days of infection, and a clear shift from the S phase to the G1 phase in the cell cycle was observed. To identify genes regulated by C/EBPβ in all four cell lines, we performed statistical analysis applying a false discovery rate of 20%, and accepted only genes with a >1,1 and <0,9 fold ratio. We identfied 435 genes regulated after C/EBPβ knockdown (117 upregulated, 318 downregulated). Classification of the differentially expressed genes into biological categories revealed overrepresentation of genes involved in the regulation of kinase activity, cell cycle and proliferation, lymphocyte differentiation, and metabolic processes. In particular, kinases involved in the regulation of JNK activity, which have been shown previously to be involved in proliferation of ALCL, were highly affected by C/EBPβ knockdown. Genomatix Bibliosphere Pathway Analysis revealed C/EBPβ to be connected to pathways involving cell cycle (RUNX3, CCNG1, CDKN2A), apoptosis (FAS, PTPRC, BCL2A1, BIRC3) and MAPK cascades (TRIB1 and several MAP3Ks). Several of the genes identified contain known C/EBPβ binding sites. Conclusions: C/EBPβ silencing induces growth arrest in ALK+ALCL, which correlates with differential expression of genes involved in cell cycle, apoptosis and differentiation. This study reveals C/EBPβ as a master transcription regulator of NPM-ALK induced cellular proliferation, and therefore, an ideal candidate for targeted therapeutic intervention.

New Pathogenetic Insights Into Classical Hodgkin Lymphoma Revealed by Gene Expression Profiling of Microdissected Hodgkin/Reed-Sternberg Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 266-266 ◽  
Author(s):  
Enrico Tiacci ◽  
Verena Brune ◽  
Susan Eckerle ◽  
Wolfram Klapper ◽  
Ines Pfeil ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
B Cell ◽  
Gene Expression Profiling ◽  
Hodgkin Lymphoma ◽  
Cell Lines ◽  
Expression Profiling ◽  
Expression Profiles ◽  
B Cell Lymphoma ◽  
Cell Phenotype

Abstract Abstract 266 Background. Previous gene expression profiling studies on cHL have been performed on whole tissue sections (mainly reflecting the prominent reactive background in which the few HRS cells are embedded), or on cHL cell lines. However, cultured HRS cells do not likely reflect primary HRS cells in all aspects, being derived from end-stage patients and from sites (e.g. pleural effusions or bone marrow) which are not typically involved by cHL and where HRS cells lost their dependence on the inflammatory microenvironment of the lymph node. Methods. ∼1000–2000 neoplastic cells were laser-microdissected from hematoxylin/eosin-stained frozen sections of lymph nodes taken at disease onset from patients with cHL (n=16) or with various B-cell lymphomas (n=35), including primary mediastinal B-cell lymphoma (PMBL) and nodular lymphocyte-predominant Hodgkin lymphoma (nLPHL). After two rounds of in vitro linear amplification, mRNA was hybridized to Affymetrix HG-U133 Plus 2.0 chips. Expression profiles were likewise generated from sorted cHL cell lines and several normal mature B-cell populations. Results. Primary and cultured HRS cells, although sharing hallmark cHL signatures such as high NF-kB transcriptional activity and lost B-cell identity, showed considerable transcriptional divergence in chemokine/chemokine receptor activity, extracellular matrix remodeling and cell adhesion (all enriched in primary HRS cells), as well as in proliferation (enriched in cultured HRS cells). Unsupervised and supervised analyses indicated that microdissected HRS cells of cHL represent a transcriptionally unique lymphoma entity, overall closer to nLPHL than to PMBL but with differential behavior of the cHL histological subtypes, being HRS cells of the lymphocyte-rich and mixed-cellularity subtypes close to nLPHL cells while HRS cells of NS and LD exhibited greater similarity to PMBL cells. HRS cells downregulated a large number of genes involved in cell cycle checkpoints and in the maintenance of genomic integrity and chromosomal stability, while upregulating gene and gene signatures involved in various oncogenic signaling pathways and in cell phenotype reprogramming. Comparisons with normal B cells highlighted the lack of consistent transcriptional similarity of HRS cells to bulk germinal center (GC) B cells or plasma cells and, interestingly, a more pronounced resemblance to CD30+ GC B cells and CD30+ extrafollicular B cells, two previously uncharacterized subsets that are transcriptionally distinct from the other mature B-cell types. Conclusions. Gene expression profiling of primary HRS cells provided several new insights into the biology and pathogenesis of cHL, its relatedness to other lymphomas and normal B cells, and its enigmatic phenotype. Disclosures: No relevant conflicts of interest to declare.

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