Genomic alterations in blastic natural killer/extranodal natural killer-like T cell lymphoma with cutaneous involvement

Cytogenetics of Blastic Plasmacytoid Dendritic Cell Neoplasm: Chromosomal Rearrangements and DNA Copy-Number Alterations

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a skin-tropic hematopoietic malignancy. Approximately 60% of cases with analyzable karyotyping results show complex karyotypes. Losses are more frequently found than copy-number gains. Recurrently deleted regions include tumor suppressor genes. No specific chromosomal abnormalities have been demonstrated in BPDCN, but genomic rearrangements involving the MYB family genes and MYC were identified. One-third of cases of BPDCN harbor the 8q24 rearrangement, most frequently with 6p21 harboring RUNX2, which is associated with immunoblastoid cytomorphology and MYC expression. MYB rearrangement is detected in 20% of patients with BPDCN. We review copy-number alterations and chromosomal rearrangements.

Pak2 regulates myeloid-derived suppressor cell development in mice

Myeloid-derived suppressor cells (MDSCs) are CD11b⁺Gr1⁺ cells that induce T-cell hyporesponsiveness, thus impairing antitumor immunity. We have previously reported that disruption of Pak2, a member of the p21-activated kinases (Paks), in hematopoietic stem/progenitor cells (HSPCs) induces myeloid lineage skewing and expansion of CD11b^highGr1^high cells in mice. In this study, we confirmed that Pak2-KO CD11b^highGr1^high cells suppressed T-cell proliferation, consistent with an MDSC phenotype. Loss of Pak2 function in HSPCs led to (1) increased hematopoietic progenitor cell sensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling, (2) increased MDSC proliferation, (3) decreased MDSC sensitivity to both intrinsic and Fas-Fas ligand-mediated apoptosis, and (4) promotion of MDSCs by Pak2-deficient CD4⁺ T cells that produced more interferon γ, tumor necrosis factor α, and GM-CSF. Pak2 disruption activated STAT5 while downregulating the expression of IRF8, a well-described myeloid transcription factor. Together, our data reveal a previously unrecognized role of Pak2 in regulating MDSC development via both cell-intrinsic and extrinsic mechanisms. Our findings have potential translational implications, as the efficacy of targeting Paks in cancer therapeutics may be undermined by tumor escape from immune control and/or acceleration of tumorigenesis through MDSC expansion.

Expression patterns of the activator protein-1 (AP-1) family members in lymphoid neoplasms

The activator protein-1 (AP-1) is a dimeric transcription factor composed of proteins belonging to the Jun (c-Jun, JunB and JunD), Fos (c-Fos, FosB, Fra1 and Fra2) and activating transcription factor protein families. AP-1 is involved in various cellular events including differentiation, proliferation, survival and apoptosis. Deregulated expression of AP-1 transcription factors is implicated in the pathogenesis of various lymphomas such as classical Hodgkin lymphomas, anaplastic large cell lymphomas, diffuse large B cell lymphomas and adult T cell leukemia/lymphoma. The main purpose of this review is the analysis of the expression patterns of AP-1 transcription factors in order to gain insight into the histophysiology of lymphoid tissues and the pathology of lymphoid malignancies.

Pak2 regulates hematopoietic progenitor cell proliferation, survival, and differentiation

p21-Activated kinase 2 (Pak2), a serine/threonine kinase, has been previously shown to be essential for hematopoietic stem cell (HSC) engraftment. However, Pak2 modulation of long-term hematopoiesis and lineage commitment remain unreported. Using a conditional Pak2 knockout mouse model, we found that disruption of Pak2 in HSCs induced profound leukopenia and a mild macrocytic anemia. Although loss of Pak2 in HSCs leads to less efficient short- and long-term competitive hematopoiesis than wild-type cells, it does not affect HSC self-renewal per se. Pak2 disruption decreased the survival and proliferation of multicytokine stimulated immature progenitors. Loss of Pak2 skewed lineage differentiation toward granulocytopoiesis and monocytopoiesis in mice as evidenced by (a) a three- to sixfold increase in the percentage of peripheral blood granulocytes and a significant increase in the percentage of granulocyte-monocyte progenitors in mice transplanted with Pak2-disrupted bone marrow (BM); (b)Pak2-disrupted BM and c-kit(+) cells yielded higher numbers of more mature subsets of granulocyte-monocyte colonies and polymorphonuclear neutrophils, respectively, when cultured in the presence of granulocyte-macrophage colony-stimulating factor. Pak2 disruption resulted, respectively, in decreased and increased gene expression of transcription factors JunB and c-Myc, which may suggest underlying mechanisms by which Pak2 regulates granulocyte-monocyte lineage commitment. Furthermore, Pak2 disruption led to (a) higher percentage of CD4(+) CD8(+) double positive T cells and lower percentages of CD4(+) CD8(-) or CD4(-) CD8(+) single positive T cells in thymus and (b) decreased numbers of mature B cells and increased numbers of Pre-Pro B cells in BM, suggesting defects in lymphopoiesis.

PAK1 is a therapeutic target in acute myeloid leukemia and myelodysplastic syndrome

Poor clinical outcome of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) has been attributed to failure of current chemotherapeutic regimens to target leukemic stem cells. We recently identified p21-activated kinase (PAK1) as a downstream effector molecule of H2.0-like homeobox (HLX), a gene functionally relevant for AML pathogenesis. In this study, we find that inhibition of PAK1 activity by small molecule inhibitors or by RNA interference leads to profound leukemia inhibitory effects both in vitro and in vivo. Inhibition of PAK1 induces differentiation and apoptosis of AML cells through downregulation of the MYC oncogene and a core network of MYC target genes. Importantly, we find that inhibition of PAK1 inhibits primary human leukemic cells including immature leukemic stem cell-enriched populations. Moreover, we find that PAK1 upregulation occurs during disease progression and is relevant for patient survival in MDS. Our studies highlight PAK1 as a novel target in AML and MDS and support the use of PAK1 inhibitors as a therapeutic strategy in these diseases.

PAK signaling in cancer

Transformation of a normal cell to a cancer cell is caused by mutations in genes that regulate proliferation, apoptosis, and invasion. Small GTPases such as Ras, Rho, Rac and Cdc42 orchestrate many of the signals that are required for malignant transformation. The p21-activated kinases (PAKs) are effectors of Rac and Cdc42. PAKs are a family of serine/threonine protein kinases comprised of six isoforms (PAK1–6), and they play important roles in cytoskeletal dynamics, cell survival and proliferation. They act as key signal transducers in several cancer signaling pathways, including Ras, Raf, NFκB, Akt, Bad and p53. Although PAKs are not mutated in cancers, they are overexpressed, hyperactivated or amplified in several human tumors and their role in cell transformation make them attractive therapeutic targets. This review discusses the evidence that PAK is important for cell transformation and some key signaling pathways it regulates. This review primarily discusses Group I PAKs (PAK1, PAK2 and PAK3) as Group II PAKs (PAK4, PAK5 and PAK6) are discussed elsewhere in this issue (by Minden).

p21-Activated protein kinases and their emerging roles in glucose homeostasis

p21-Activated protein kinases (PAKs) are centrally involved in a plethora of cellular processes and functions. Their function as effectors of small GTPases Rac1 and Cdc42 has been extensively studied during the past two decades, particularly in the realms of cell proliferation, apoptosis, and hence tumorigenesis, as well as cytoskeletal remodeling and related cellular events in health and disease. In recent years, a large number of studies have shed light onto the fundamental role of group I PAKs, most notably PAK1, in metabolic homeostasis. In skeletal muscle, PAK1 was shown to mediate the function of insulin on stimulating GLUT4 translocation and glucose uptake, while in pancreatic β-cells, PAK1 participates in insulin granule localization and vesicle release. Furthermore, we demonstrated that PAK1 mediates the cross talk between insulin and Wnt/β-catenin signaling pathways and hence regulates gut proglucagon gene expression and the production of the incretin hormone glucagon-like peptide-1 (GLP-1). The utilization of chemical inhibitors of PAK and the characterization of Pak1(-/-) mice enabled us to gain mechanistic insights as well as to assess the overall contribution of PAKs in metabolic homeostasis. This review summarizes our current understanding of PAKs, with an emphasis on the emerging roles of PAK1 in glucose homeostasis.

Downregulation of miR-15a due to LMP1 promotes cell proliferation and predicts poor prognosis in nasal NK/T-cell lymphoma

Nasal NK/T-cell lymphoma (NNKTL) is an Epstein-Barr virus (EBV)-associated malignancy and has distinct clinical and histological features. However, its genetic features are hitherto unclear. MicroRNAs (miRNAs) play a crucial role in the pathogenesis of several malignancies via regulating gene expression. In this study, we investigated whether the specific microRNAs were related to the tumor behaviors in NNKTL. MiRNA array and Quantitative RT-PCR analyses revealed that miR-15a was expressed at a much lower level in NNKTL cells (SNK-1, SNK-6, and SNT-8) than in normal peripheral NK cells and EBV-negative NK cell line KHYG-1. Quantitative PCR and western blot analyses showed that the expression of MYB and cyclin D1, which are validated targets of miR-15a, was higher in NNKTL cells. Transfection of NNKTL cells (SNK-6 and SNT-8) with a miR-15a precursor decreased MYB and cyclin D1 levels, thereby blocking G1/S transition and cell proliferation. Knockdown of EBV-encoded latent membrane protein 1 (LMP1) significantly increased miR-15a expression in SNK-6 cells. In NNKTL tissues, we found that reduced miR-15a expression, which correlated with MYB and cyclin D1 expression, was associated with poor prognosis of NNKTL patients. These data suggest that downregulation of miR-15a, possibly due to LMP1, implicates in the pathogenesis of NNKTL by inducing cell proliferation via MYB and cyclin D1. Thus, miR-15a could be a potential target for antitumor therapy and a prognostic predictor for NNKTL.

The c-Rel Transcription Factor in Development and Disease

c-Rel is a member of the nuclear factor κB (NF-κB) transcription factor family. Unlike other NF-κB proteins that are expressed in a variety of cell types, high levels of c-Rel expression are found primarily in B and T cells, with many c-Rel target genes involved in lymphoid cell growth and survival. In addition to c-Rel playing a major role in mammalian B and T cell function, the human c-rel gene (REL) is a susceptibility locus for certain autoimmune diseases such as arthritis, psoriasis, and celiac disease. The REL locus is also frequently altered (amplified, mutated, rearranged), and expression of REL is increased in a variety of B and T cell malignancies and, to a lesser extent, in other cancer types. Thus, agents that modulate REL activity may have therapeutic benefits for certain human cancers and chronic inflammatory diseases.

PAK1 as a therapeutic target

IMPORTANCE OF THE FIELD

P21-activated kinases (PAKs) are involved in multiple signal transduction pathways in mammalian cells. PAKs, and PAK1 in particular, play a role in such disorders as cancer, mental retardation and allergy. Cell motility, survival and proliferation, the organization and function of cytoskeleton and extracellular matrix, transcription and translation are among the processes affected by PAK1.

AREAS COVERED IN THIS REVIEW

We discuss the mechanisms that control PAK1 activity, its involvement in physiological and pathophysiological processes, the benefits and the drawbacks of the current tools to regulate PAK1 activity, the evidence that suggests PAK1 as a therapeutic target and the likely directions of future research.

WHAT THE READER WILL GAIN

The reader will gain a better knowledge and understanding of the areas described above.

TAKE HOME MESSAGE

PAK1 is a promising therapeutic target in cancer and allergen-induced disorders. Its suitability as a target in vascular, neurological and infectious diseases remains ambiguous. Further advancement of this field requires progress on such issues as the development of specific and clinically acceptable inhibitors, the choice between targeting one or multiple PAK isoforms, elucidation of the individual roles of PAK1 targets and the mechanisms that may circumvent inhibition of PAK1.

Effects of the NUP98-DDX10 oncogene on primary human CD34+ cells: role of a conserved helicase motif

NUP98 gene rearrangements occur in acute myeloid leukemia and result in the expression of fusion proteins. One of the most frequent is NUP98-DDX10 that fuses a portion of NUP98 to a portion of DDX10, a putative DEAD-box RNA helicase. Here we show that NUP98-DDX10 dramatically increases proliferation and self-renewal of primary human CD34+ cells, and disrupts their erythroid and myeloid differentiation. It localizes to their nuclei and extensively deregulates gene expression. Comparison to another leukemogenic NUP98 fusion, NUP98-HOXA9, reveals a number of genes deregulated by both oncoproteins, including HOX genes, COX-2, MYCN, ANGPT1, REN, HEY1, SOX4, and others. These genes may account for the similar leukemogenic properties of NUP98 fusion oncogenes. The YIHRAGRTAR sequence in the DDX10 portion of NUP98-DDX10 represents a major motif shared by DEAD-box RNA helicases that is required for ATP binding, RNA-binding, and helicase functions. Mutating this motif diminished the in vitro transforming ability of NUP98-DDX10, indicating that it plays a role in leukemogenesis. These data demonstrate for the first time the in vitro transforming ability of NUP98-DDX10 and show that it is partially dependent on one of the consensus helicase motifs of DDX10. They also point to common pathways that may underlie leukemogenesis by different NUP98 fusions.

Alterations of the cell-cycle inhibitors p27(KIP1) and p16(INK4a) are frequent in blastic plasmacytoid dendritic cell neoplasms

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, clinically aggressive malignancy with a median survival of 12-14 months. To identify pathogenetic relevant genomic aberrations and molecular targets for therapy, we analyzed skin biopsy samples obtained from 14 patients using high-resolution array-based comparative genomic hybridization and immunostaining. Losses of chromosomes 9, 12, 13, and 15 were detected most frequently. Loss of the CDKN1B locus was the most common finding and was detected in 64% of tumors. In all but one case, the dose-dependent haploinsufficient cell-cycle inhibitor p27(KIP1), encoded by CDKN1B, was weakly expressed in the nuclei of tumor cells. Losses of the CDKN2A-ARF-CDKN2B locus occurred in 50% of patients, and in one case a distinct biallelic loss was identified. The cell-cycle inhibitor p16(INK4a), which is encoded by CDKN2A, was not expressed in tumor cells, suggesting a complete loss of function. Loss of chromosome 13, including the RB1 gene, was observed in 43% of tumors. These results imply that alterations of the cell-cycle checkpoint controlling proteins p27(KIP1), p16(INK4a), and RB1 may exert a profound effect in malignant transformation in BPDCN. The elucidation of the affected pathways may guide the development of new treatments specifically designed for this aggressive disease entity.

Pak protein kinases and their role in cancer

Some of the characteristics of cancer cells are high rates of cell proliferation, cell survival, and the ability to invade surrounding tissue. The cytoskeleton has an essential role in these processes. Dynamic changes in the cytoskeleton are necessary for cell motility and cancer cells are dependent on motility for invasion and metastasis. The signaling pathways behind the reshaping and migrating properties of the cytoskeleton in cancer cells involve a group of Ras-related small GTPases and their effectors, including the p21-activated kinases (Paks). Paks are a family of serine/threonine protein kinases comprised of six isoforms (Pak 1-6), all of which are direct targets of the small GTPases Rac and Cdc42. Besides their role in cytoskeletal dynamics, Paks have recently been shown to regulate various other cellular activities, including cell survival, mitosis, and transcription. Paks are overexpressed and/or hyperactivated in several human tumors and their role in cell transformation makes them attractive therapeutic targets. Pak-targeted therapeutics may efficiently inhibit certain types of tumors and efforts to identify selective Pak-inhibitors are underway.

Natural killer cell lymphoma/leukemia with homozygous loss ofp27/kip1

We describe a case of natural killer (NK) cell lymphoma/leukemia with only an interstitial deletion in the short arm of chromosome 12 as the primary event. Fluorescence in situ hybridization revealed that the ETV6 locus (12p13) and subtelomeric sequences are not deleted in the process. The p27/kip1 locus (12p12-13), a candidate tumor suppressor gene, was deleted on the abnormal chromosome. Sequence analysis detected an adenine nucleotide deletion in the third codon of exon 1 leading to frameshift and premature termination at codon 41 of the retained copy of p27/kip1. To the best of our knowledge, this is the first report in literature on a NK cell lymphoma/leukemia with complete loss of p27/kip1.

Abnormal AP-1 protein expression in primary cutaneous B-cell lymphomas

BACKGROUND

Primary cutaneous B-cell lymphoma (PCBCL) consists mainly of primary cutaneous marginal zone B-cell lymphoma (PCMZL), primary cutaneous follicle centre lymphoma (PCFCL) and primary cutaneous large B-cell lymphoma, leg type (PCLBCL-LT). The activator protein 1 (AP-1) transcription factor includes JUN, FOS and other family members.

OBJECTIVES

To assess the expression pattern of AP-1 transcription factors in PCBCL.

METHODS

We analysed paraffin tissue sections from nine cases of PCMZL, seven PCFCL, six PCLBCL-LT and two unspecified PCBCL cases by using immunohistochemistry with antibodies against c-JUN, JUNB, JUND, c-FOS, RAF1, alphaPAK, CD30 and CCND1.

RESULTS

A positive staining for JUND (++) was observed in six cases of PCFCL (86%), five PCLBCL-LT (83%) and five PCMZL (56%). Positive CCND1 protein expression was present in four cases of PCLBCL-LT (67%), four PCFCL (57%) and four PCMZL (44%), and the two unspecified PCBCL cases. Expression of alphaPAK protein was seen in three cases of PCLBCL-LT (50%), two PCMZL (22%) and one PCFCL. However, c-JUN, c-FOS and RAF1 protein were rarely expressed in the PCBCL cases analysed; JUNB and CD30 protein expression was absent in these cases.

CONCLUSIONS

These findings suggest that the presence of abnormal AP-1 protein expression is associated with upregulation of JUND, CCND1 and alphaPAK and downregulation of JUNB in PCBCL.

Mutations in the NF-kappaB signaling pathway: implications for human disease

The nuclear factor-kappa B (NF-kappaB) signaling pathway is a multi-component pathway that regulates the expression of hundreds of genes that are involved in diverse and key cellular and organismal processes, including cell proliferation, cell survival, the cellular stress response, innate immunity and inflammation. Not surprisingly, mis-regulation of the NF-kappaB pathway, either by mutation or epigenetic mechanisms, is involved in many human and animal diseases, especially ones associated with chronic inflammation, immunodeficiency or cancer. This review describes human diseases in which mutations in the components of the core NF-kappaB signaling pathway have been implicated and discusses the molecular mechanisms by which these alterations in NF-kappaB signaling are likely to contribute to the disease pathology. These mutations can be germline or somatic and include gene amplification (e.g., REL), point mutations and deletions (REL, NFKB2, IKBA, CYLD, NEMO) and chromosomal translocations (BCL-3). In addition, human genetic diseases are briefly described wherein mutations affect protein modifiers or transducers of NF-kappaB signaling or disrupt NF-kappaB-binding sites in promoters/enhancers.

Gene-expression profiling and array-based CGH classify CD4+CD56+ hematodermic neoplasm and cutaneous myelomonocytic leukemia as distinct disease entities

CD4+CD56+ hematodermic neoplasm (CD4+CD56+HN) is an aggressive hematopoietic malignancy with distinct clinicopathologic and immunophenotypic features that commonly involve the skin, bone marrow, and blood. Differentiation from cutaneous myelomonocytic leukemia (c-AML) may be exceedingly difficult and requires extensive phenotyping. The molecular mechanisms involved in the development of CD4+CD56+HN are largely unresolved. Moreover, recurrent chromosomal alterations have not yet been precisely defined in CD4+CD56+HN and c-AML. In the present study an integrated genomic analysis using expression profiling and array-based comparative genomic hybridization (CGH) was performed on lesional skin biopsy samples of patients with CD4+CD56+HN and c-AML. Our results demonstrate that CD4+CD56+HN and c-AML show distinct gene-expression profiles and distinct patterns of chromosomal aberrations. CD4+CD56+HN is characterized by recurrent deletion of regions on chromosome 4 (4q34), chromosome 9 (9p13-p11 and 9q12-q34), and chromosome 13 (13q12-q31) that contain several tumor suppressor genes with diminished expression (Rb1, LATS2). Elevated expression of the oncogenes HES6, RUNX2, and FLT3 was found but was not associated with genomic amplification. We noted high expression of various plasmacytoid dendritic-cell (pDC)–related genes, pointing to the cell of origin of this malignancy.

Common and contrasting genomic profiles among the major human lung cancer subtypes

Lung cancer is the leading cause of cancer mortality worldwide. With the recent success of molecularly targeted therapies in this disease, a detailed knowledge of the spectrum of genetic lesions in lung cancer represents a critical step in the development of additional effective agents. An integrated high-resolution survey of regional amplifications and deletions and gene expression profiling of non-small-cell lung cancers (NSCLC) identified 93 focal high-confidence copy number alterations (CNAs), with 21 spanning less than 0.5 Mb with a median of five genes. Most CNAs were novel and included high-amplitude amplification and homozygous deletion events. Pathogenic relevance of these genomic alterations was further reinforced by their recurrence and overlap with focal alterations of other tumor types. Additionally, the comparison of the genomic profiles of the two major subtypes of NSCLC, adenocarcinoma (AC) and squamous cell carcinoma (SCC), showed an almost complete overlap with the exception of one amplified region on chromosome 3, specific for SCC. Among the few genes overexpressed within this amplicon was p63, a known regulator of squamous cell differentiation. These findings suggest that the AC and SCC subtypes may arise from a common cell of origin and they are driven to their distinct phenotypic end points by altered expression of a limited number of key genes such as p63.

Heterogeneous Abnormalities of CCND1 and RB1 in Primary Cutaneous T-Cell Lymphomas Suggesting Impaired Cell Cycle Control in Disease Pathogenesis

Upregulation of cyclin D1/B-cell leukemia/lymphoma 1 (CCND1/BCL1) is present in most mantle cell lymphomas with the t(11;14)(q13;q32) translocation. However, little is known about the abnormalities of CCND1 and its regulator RB1 in primary cutaneous T-cell lymphomas (CTCL). We analyzed CCND and RB status in CTCL using fluorescent in situ hybridization (FISH), immunohistochemistry (IHC), and Affymetrix expression microarray. FISH revealed loss of CCND1/BCL1 in five of nine Sézary syndrome (SS) cases but gain in two cases, and RB1 loss in four of seven SS cases. IHC showed absent CCND1/BCL1 expression in 18 of 30 SS, 10 of 23 mycosis fungoides (MF), and three of 10 primary cutaneous CD30+ anaplastic large-cell lymphoma (C-ALCL). Increased CCND1/BCL1 expression was seen in nine MF, seven C-ALCL, and six SS cases. Absent RB1 expression was detected in 8 of 12 MF and 7 of 9 SS cases, and raised RB1 expression in 7 of 8 C-ALCL. Affymetrix revealed increased gene expression of CCND2 in four of eight CTCL cases, CCND3 in three cases, and CDKN2C in two cases with a normal expression of CCND1 and RB1. These findings suggest heterogeneous abnormalities of CCND and RB in CTCL, in which dysregulated CCND and RB1 may lead to impaired cell cycle control.

Genetic losses in breast cancer: toward an integrated molecular cytogenetic map

Breast cancer is the most common malignant disease in Caucasian women, but is less frequent in Chinese women. The molecular basis for such ethnical difference in disease pathogenesis remains unknown. To address this issue, we performed allelotyping analysis of formalin-fixed, paraffin-embedded samples from 21 Chinese patients with breast cancer using 59 fluorescently tagged oligonucleotide primers amplifying microsatellite loci. Loss of heterozygosity (LOH) was found in all tumor samples. Frequent allelic losses were identified at markers D3S1578 (56%); D7S507 (55%); D1S2766 (50%); D17S789 and D17S946 (43% each); D19S814 (35%); D2S162, D13S158 and D13S296 (33% each); D1S551 and D1S2800 (29% each); D3S1597 and D6S260 (22% each); and D1S1588 (21%). To compare our data to previous reports, we determined the band-specific frequency of chromosomal imbalances in breast cancer karyotypes reported in the Mitelman database, and from the CGH results of cases accessible through the Progenetix website. Furthermore, published LOH analyses of breast cancer cases were compared to our own LOH results, demonstrating the most common chromosomal regions affected by allelic losses. The combined results provide a comprehensive view of genetic losses in breast cancers, indicating the comparability of these different techniques and suggesting the presence of a distinct subset of breast cancers with high-frequency LOH at chromosomes 1 and 2p in Chinese patients.

BCL2 and JUNB abnormalities in primary cutaneous lymphomas

BACKGROUND

BCL2 is upregulated in nodal and extranodal B-cell non-Hodgkin's lymphomas, with a consequent antiapoptotic effect. However, loss of BCL2 has also been noted in some malignancies, suggesting a different molecular pathogenesis.

OBJECTIVES

To investigate genomic and protein expression status of BCL2 and to compare the results with that of JUNB in primary cutaneous lymphomas (PCLs).

METHODS

We analysed gene copy number of BCL2 and JUNB in 88 DNA samples from 80 patients with PCL consisting of Sézary syndrome/mycosis fungoides (SS/MF), primary cutaneous B-cell lymphoma (PCBCL) and primary cutaneous CD30+ anaplastic large cell lymphoma (C-ALCL) by the use of real-time polymerase chain reaction (PCR) and immunohistochemistry (IHC). Real-time PCR and IHC findings were subsequently compared with the results of additional fluorescent in situ hybridization (FISH) analysis of 23 cases of SS and Affymetrix cDNA expression microarray study of two primary cutaneous T-cell lymphoma (CTCL) cell lines.

RESULTS

Real-time PCR analysis showed loss of BCL2 gene copy number in 22 of 80 PCL cases (28%), including 17 of 42 SS/MF, three of 13 C-ALCL and two of 33 PCBCL samples, and gain of BCL2 in four PCBCL samples. Gain of JUNB was identified in 18 of 71 PCL cases (25%), including nine of 35 SS/MF, seven of 13 C-ALCL and two of 31 PCBCL samples. IHC analysis revealed absent nuclear expression of BCL2 protein in 47 of 73 PCL cases, comprising 28 of 36 SS/MF, eight of eight C-ALCL and 11 of 29 PCBCL cases. In contrast, BCL2 protein expression was detected in 26 of 73 PCL cases, consisting of 18 of 29 PCBCL and eight of 36 SS/MF cases. JUNB protein expression was present in tumour cells from 30 of 33 of SS/MF and eight of eight C-ALCL, and was absent in tumour cells from 18 of 27 PCBCL cases. A comparison between BCL2 and JUNB revealed loss of BCL2 and gain of JUNB in five of 35 SS/MF samples, and expression of JUNB protein and absent BCL2 expression in 25 SS/MF and eight of eight C-ALCL cases. In contrast, expression of BCL2 and absent JUNB expression were detected in 67% of PCBCL cases. Additional FISH analysis revealed deletion of BCL2 in 19 of 23 SS cases (83%), including eight cases with BCL2 loss shown by real-time PCR. Furthermore, Affymetrix expression microarray demonstrated decreased expression of proapoptotic and antiapoptotic genes involved in BCL2 signalling pathways such as BOK, BIM, HRK, RASA1 and STAT2 in two CTCL cell lines with BCL2 loss and absent BCL2 expression. Increased expression of JUNB was also identified in the MF cell line.

CONCLUSIONS

These findings provide a comprehensive assessment of BCL2 and JUNB status in PCL, and suggest that there is a selection pressure in a subset of CTCL cases for tumour cells showing BCL2 loss and upregulation of JUNB primarily through chromosomal deletion and amplification, respectively.

The role of molecular studies in lymphoma diagnosis: a review

Lymphoma classification is based on a multiparametric approach to diagnosis, in which clinical features, morphology, immunophenotype, karyotype and molecular characteristics are important to varying degrees. While in most cases, a diagnosis can be confidently established on the basis of morphology and immunophenotype alone, a small proportion of diagnostically difficult cases will rely on molecular studies to enable a definitive diagnosis. This review discusses the various molecular techniques available including Southern blotting (SB), polymerase chain reaction (PCR), fluorescence in situ hybridisation (FISH)--including multicolour-FISH/spectral karyotyping and comparative genomic hybridisation--and also gene expression profiling using cDNA microarray technology. Emphasis is given to the analysis of antigen receptor gene rearrangements and chromosomal translocations as they relate to lymphoma diagnosis and also in the setting of minimal residual disease (MRD) detection and monitoring. Laboratories performing these tests need to have expertise in these areas of testing, and there is a need for greater standardisation of molecular tests. It is important to know the sensitivity and specificity of each test as well as its limitations and the pitfalls in the interpretation of results. Above all, results of molecular testing should never be considered in isolation, and must always be interpreted in the context of clinical and other laboratory data.

Primary Peripheral T-Cell Lymphoma of the Face Other Than Mycosis Fungoides

OBJECTIVE

To describe the radiologic findings of primary peripheral T-cell lymphoma (PTCL) of the face other than mycosis fungoides.

METHODS

Computed tomography (CT) and magnetic resonance imaging (MRI) findings of 5 consecutive patients with pathologically proven primary facial PTCL other than mycosis fungoides were retrospectively evaluated. Patients with PTCL involving the sinonasal cavity or lymph nodes were excluded.

RESULTS

Diagnoses of patients included in this study consisted of natural killer/T-cell lymphoma (n = 2), subcutaneous panniculitis-like T-cell lymphoma (n = 1), anaplastic large cell lymphoma (n = 1), and PTCL not otherwise specified (n = 1). Infiltration or swelling of the superficial space of the face was noted on both CT and MRI, mimicking inflammation or infection. Also seen were well-enhancing small nodular (n = 2) or infiltrative mass-like lesions (n = 2) within the areas of infiltration, which showed intermediate signal intensity on T2-weighted images. One patient demonstrated infiltration and swelling alone.

CONCLUSIONS

Primary facial PTCL is a rarely encountered tumor and demonstrates infiltration or swelling mimicking inflammation or infection. Nodular or infiltrative mass-like lesions may be helpful for its diagnosis.