Chromosomal abnormalities in relation to clinical disease in patients with cutaneous T-cell lymphoma: a 5-year follow-up study

Understanding Cell Lines, Patient-Derived Xenograft and Genetically Engineered Mouse Models Used to Study Cutaneous T-Cell Lymphoma

Cutaneous T cell lymphoma (CTCL) is a spectrum of lymphoproliferative disorders caused by the infiltration of malignant T cells into the skin. The most common variants of CTCL include mycosis fungoides (MF), Sézary syndrome (SS) and CD30⁺ Lymphoproliferative disorders (CD30⁺ LPDs). CD30⁺ LPDs include primary cutaneous anaplastic large cell lymphoma (pcALCL), lymphomatoid papulosis (LyP) and borderline CD30⁺ LPD. The frequency of MF, SS and CD30⁺ LPDs is ~40–50%, <5% and ~10–25%, respectively. Despite recent advances, CTCL remains challenging to diagnose. The mechanism of CTCL carcinogenesis still remains to be fully elucidated. Hence, experiments in patient-derived cell lines and xenografts/genetically engineered mouse models (GEMMs) are critical to advance our understanding of disease pathogenesis. To enable this, understanding the intricacies and limitations of each individual model system is highly important. Presently, 11 immortalized patient-derived cell lines and different xenograft/GEMMs are being used to study the pathogenesis of CTCL and evaluate the therapeutic efficacy of various treatment modalities prior to clinical trials. Gene expression studies, and the karyotyping analyses of cell lines demonstrated that the molecular profile of SeAx, Sez4, SZ4, H9 and Hut78 is consistent with SS origin; MyLa and HH resemble the molecular profile of advanced MF, while Mac2A and PB2B represent CD30⁺ LPDs. Molecular analysis of the other two frequently used Human T-Cell Lymphotropic Virus-1 (HTLV-1)⁺ cell lines, MJ and Hut102, were found to have characteristics of Adult T-cell Leukemia/Lymphoma (ATLL). Studies in mouse models demonstrated that xenograft tumors could be grown using MyLa, HH, H9, Hut78, PB2B and SZ4 cells in NSG (NOD Scid gamma mouse) mice, while several additional experimental GEMMs were established to study the pathogenesis, effect of drugs and inflammatory cytokines in CTCL. The current review summarizes cell lines and xenograft/GEMMs used to study and understand the etiology and heterogeneity of CTCL.

From Benign Inflammatory Dermatosis to Cutaneous Lymphoma. DNA Copy Number Imbalances in Mycosis Fungoides versus Large Plaque Parapsoriasis

Background and Objectives: Mycosis fungoides (MF) and large plaque parapsoriasis (LPP) evolution provide intriguing data and are the cause of numerous debates. The diagnosis of MF and LPP is associated with confusion and imprecise definition. Copy number alterations (CNAs) may play an essential role in the genesis of cancer out of genes expression dysregulation. Objectives: Due to the heterogeneity of MF and LPP and the scarcity of the cases, there are an exceedingly small number of studies that have identified molecular changes in these pathologies. We aim to identify and compare DNA copy number alterations and gene expression changes between MF and LPP to highlight the similarities and the differences between these pathologies. Materials and Methods: The patients were prospectively selected from University Clinic of Dermatology and Venereology Timișoara, Romania. From fresh frozen skin biopsies, we extracted DNA using single nucleotide polymorphism (SNP) data. The use of SNP array for copy number profiling is a promising approach for genome-wide analysis. Results: After reviewing each group, we observed that the histograms generated for chromosome 1–22 were remarkably similar and had a lot of CNAs in common, but also significant differences were seen. Conclusions: This study took a step forward in finding out the differences and similarities between MF and LPP, for a more specific and implicitly correct approach of the case. The similarity between these two pathologies in terms of CNAs is striking, emphasizing once again the difficulty of approaching and differentiating them.

DNA copy number imbalances in primary cutaneous lymphomas

BACKGROUND

Cutaneous lymphomas (CL) represent a clinically defined group of extranodal non-Hodgkin lymphomas harbouring heterogeneous and incompletely delineated molecular aberrations. Over the past decades, molecular studies have identified several chromosomal aberrations, but the interpretation of individual genomic studies can be challenging.

OBJECTIVE

With a comprehensive meta-analysis, we aim to delineate genomic alterations for different types of CL and propose a more accurate classification in line with their various pathogenicity.

METHODS

We searched PubMed and ISI Web of Knowledge for publications from 1996 to 2016 reporting the investigation of CL for genome-wide copy number alterations, by means of comparative genomic hybridization techniques and whole-genome sequencing and whole-exome sequencing. We then extracted and remapped the available copy number variation (CNV) data from these publications with the same pipeline and performed clustering and visualisation to aggregate samples of similar CNV profiles.

RESULTS

For 449 samples from 22 publications, CNV data were accessible for sample based meta-analysis. Our findings illustrate structural and numerical chromosomal imbalance patterns. Most frequent CNAs were linked to oncogenes or tumour suppressor genes with important roles in the course of the disease.

CONCLUSION

Summary profiles for genomic imbalances, generated from case-specific data, identified complex genomic imbalances, which could discriminate between different subtypes of CL and promise a more accurate classification. The collected data presented in this study are publicly available through the 'Progenetix' online repository.

Oncogenomic analysis identifies novel biomarkers for tumor stage mycosis fungoides

Patients with mycosis fungoides (MF) developing tumors or extracutaneous lesions usually have a poor prognosis with no cure has so far been available. To identify potential novel biomarkers for MF at the tumor stage, a genomic mapping of 41 cutaneous lymphoma biopsies was used to explore for significant genes.The gene expression profiling datasets of MF were obtained from Gene Expression Omnibus database (GEO). Gene modules were simulated using Weighted Gene Co-expression Network Analysis (WGCNA) and the top soft-connected genes (hub genes) were filtrated with a threshold (0.5). Subsequently, module eigengenes were calculated and significant biological pathways were enriched based on the KEGG database.Four genetic modules were simulated with 3263 genes collected from the whole genomic profile based on cutoff values. Significant diseases genetic terminologies associated with tumor stage MF were found in black module. Subsequently, 13 hub genes including CFLAR, GCNT2, IFNG, IL17A, IL22, MIP, PLCG1, PTH, PTPN6, REG1A, SNAP25, SUPT7L, and TP63 were shown to be related to cutaneous T-cell lymphoma (CTCL) and adult T-cell lymphoma/leukemia (ATLL).In summary, in addition to the reported genes (IL17F, PLCG1, IFNG, and PTH) in CTCL/ATLL, the other high instable genes may serve as novel biomarkers for the regulation of the biological processes and molecular mechanisms of CTLT (MF/SS).

Analysis of CTCL cell lines reveals important differences between mycosis fungoides/Sézary syndrome vs. HTLV-1+ leukemic cell lines

HTLV-1 is estimated to affect ~20 million people worldwide and in ~5% of carriers it produces Adult T-Cell Leukemia/Lymphoma (ATLL), which can often masquerade and present with classic erythematous pruritic patches and plaques that are typically seen in Mycosis Fungoides (MF) and Sézary Syndrome (SS), the most recognized variants of Cutaneous T-Cell Lymphomas (CTCL). For many years the role of HTLV-1 in the pathogenesis of MF/SS has been hotly debated. In this study we analyzed CTCL vs. HTLV-1⁺ leukemic cells. We performed G-banding/spectral karyotyping, extensive gene expression analysis, TP53 sequencing in the 11 patient-derived HTLV-1⁺ (MJ and Hut102) vs. HTLV-1^- (Myla, Mac2a, PB2B, HH, H9, Hut78, SZ4, Sez4 and SeAx) CTCL cell lines. We further tested drug sensitivities to commonly used CTCL therapies and studied the ability of these cells to produce subcutaneous xenograft tumors in NOD.Cg-Prkdc^scid Il2rg^tm1Wjl/SzJ mice. Our work demonstrates that unlike classic advanced MF/SS cells that acquire many ongoing balanced and unbalanced chromosomal translocations, HTLV-1⁺ CTCL leukemia cells are diploid and exhibit only a minimal number of non-specific chromosomal alterations. Our results indicate that HTLV-1 virus is likely not involved in the pathogenesis of classic MF/SS since it drives a very different pathway of lymphomagenesis based on our findings in these cells. This study also provides for the first time a comprehensive characterization of the CTCL cells with respect to gene expression profiling, TP53 mutation status, ability to produce tumors in mice and response to commonly used therapies.

TruSeq-Based Gene Expression Analysis of Formalin-Fixed Paraffin-Embedded (FFPE) Cutaneous T-Cell Lymphoma Samples: Subgroup Analysis Results and Elucidation of Biases from FFPE Sample Processing on the TruSeq Platform

Cutaneous T-cell lymphomas (CTCLs) are a heterogeneous group of malignancies with courses ranging from indolent to potentially lethal. We recently studied in a 157 patient cohort gene expression profiles generated by the TruSeq targeted RNA gene expression sequencing. We observed that the sequencing library quality and depth from formalin-fixed paraffin-embedded (FFPE) skin samples were significantly lower when biopsies were obtained prior to 2009. We also observed that the fresh CTCL samples clustered together, even though they included stage I–IV disease. In this study, we compared TruSeq gene expression patterns in older (≤2008) vs. more recent (≥2009) FFPE samples to determine whether these clustering analyses and earlier described differentially expressed gene findings are robust when analyzed based on the year of biopsy. We also explored biases found in FFPE samples when subjected to the TruSeq analysis of gene expression. Our results showed that ≤2008 and ≥2009 samples clustered equally well to the full data set and, importantly, both analyses produced nearly identical trends and findings. Specifically, both analyses enriched nearly identical DEGs when comparing benign vs. (1) stage I–IV and (2) stage IV (alone) CTCL samples. Results obtained using either ≤2008 or ≥2009 samples were strongly correlated. Furthermore, by using subgroup analyses, we were able to identify additional novel differentially expressed genes (DEGs), which did not reach statistical significance in the prior full data set analysis. Those included CTCL-upregulated BCL11A, SELL, IRF1, SMAD1, CASP1, BIRC5, and MAX and CTCL-downregulated MDM4, SERPINB3, and THBS4 genes. With respect to sample biases, no matter if we performed subgroup analyses or full data set analysis, fresh samples tightly clustered together. While principal component analysis revealed that fresh samples were spatially closer together, indicating some preprocessing batch effect, they remained in the proximity to other normal/benign and FFPE CTCL samples and were not clustering as outliers by themselves. Notably, this did not affect the determination of DEGs when analyzing ≥2009 samples (fresh and FFPE biopsies) vs. ≥2009 FFPE samples alone.

Mycosis fungoides and Sézary syndrome

The development of array comparative genomic hybridization (aCGH) techniques has allowed to characterize more precisely several human neoplasms with the aim of providing prognostic markers and targets for directed therapeutic intervention. Recently, several studies applying aCGH technique have been reported in which an exhaustive genetic characterization of mycosis fungoides (MF) and Sézary syndrome (SS) has been performed. Regarding MF, a genomic profile characterized by the gains of 7q, 17q, and 8q and losses in 9p, 13q, 17p, and 10q has been described. In SS, the most common abnormalities are gains in 8q and 17q and losses at 17p and 10q. One of the main contributions of the aCGH studies in MF and SS has been the description of genetic markers associated with a poor prognosis. In MF, three specific chromosomal regions, 9p21.3 (CDKN2A, CDKN2B, and MTAP), 8q24.21 (MYC), and 10q26qter (MGMT and EBF3) have been defined as prognostic markers exhibiting a significant correlation with overall survival (P = 0.042, P = 0.017, and P = 0.022, respectively). Moreover, two MF genomic subgroups have been described, distinguishing a stable group (0-5 DNA aberrations) and an unstable group (>5 DNA aberrations), showing that the genomic unstable group had a shorter overall survival (P = 0.05).

Molecular diagnostic strategies: a role in the practice of dermatology

Molecular diagnostic strategies are gaining wider acceptance and use in dermatology and dermatopathology as more practitioners in this field develop an understanding of the principles and applications of genomic technologies. Molecular testing is facilitating more accurate diagnosis, staging, and prognostication, in addition to guiding the selection of appropriate treatment, monitoring of therapy, and identification of novel therapeutic targets, for a wide variety of skin diseases.

Genetic alterations in Sezary syndrome

Sezary syndrome (SS) is a rare form of cutaneous T-cell lymphoma characterized by erythroderma and the presence of Sezary cells in the skin, lymph nodes, and peripheral blood. Over the past few decades, cytogenetic and molecular cytogenetic findings have revealed many genetic alterations in patients with SS. The most frequent genetic lesions include monosomy 10, losses of 10q and 17p, gains of 8q24 and 17q, and diverse structural alterations involving these regions. Expression patterns in regions of genomic imbalance show that a large number of genes in SS are deregulated, and this might have a causative role in oncogenesis. Overall, chromosomal instability is characteristic of this lymphoma and related to a poor prognosis, but no specific abnormalities that may be directly involved in development of the disease have yet been found.

Array-based comparative genomic hybridization in early-stage mycosis fungoides: recurrent deletion of tumor suppressor genes BCL7A, SMAC/DIABLO, and RHOF

The etiology of mycosis fungoides (MF), the most frequent form of cutaneous T cell lymphoma (CTCL), is poorly understood. No specific genetic aberration has been detected, especially in early-stage disease, possibly due to the clinical and histological heterogeneity of patient series and to the different sources of malignant cells (skin, blood, or lymph node) included in most studies. Frozen skin biopsies from 16 patients with early-stage MF were studied using array-based comparative genomic hybridization. A DNA pool from healthy donors was used as the reference. Results demonstrated recurrent loss of 19, 7p22.1-p22.3, 7q11.1-q11.23, 9q34.12, 12q24.31, and 16q22.3-q23.1, and gain of 8q22.3-q23.1 and 21q22.12. The 12q24.31 region was recurrently deleted in 7/16 patients. Real-time PCR investigation for deletion of genes BCL7A, SMAC/DIABLO, and RHOF-three tumor suppressor genes with a putative role in hematological malignancies-demonstrated that they were deleted in 9, 10, and 13 cases, respectively. The identified genomic alterations and individual genes could yield important insights into the early steps of MF pathogenesis.

Cytogenetic and molecular analysis of MLL rearrangements in acute lymphoblastic leukaemia survivors

The successful treatment of paediatric malignancies by multimodal therapy has improved outcomes for children with cancer, especially those with acute lymphoblastic leukaemia (ALL). Second malignant neoplasms, however, represent a serious complication after treatment. Depending on dosage, 2-12% of patients treated with topoisomerase II inhibitors and/or alkylating agents develop treatment-related acute myeloid leukaemia characterized by translocations at 11q23. Our goal was to study MLL rearrangements in peripheral lymphocytes using cytogenetic and molecular methods in order to evaluate the late effects of cancer therapy in patients previously treated for childhood ALL. Chromosomal rearrangements at 11q23 were analysed in cytogenetic preparations from 49 long-term ALL survivors and 49 control individuals. Patients were subdivided depending on the inclusion or omission of topoisomerase II inhibitors (VP-16 and/or VM-26) in their treatment protocol. The statistical analysis showed significant (P = 0.007) differences between the frequency of translocations observed for the groups of patients and controls. These differences were also significant (P = 0.006) when the groups of patients (independent of the inclusion of topoisomerase II inhibitors) and controls were compared (P = 0.006). The frequencies of extra signals, however, did not differ between groups of patients and controls. Several MLL translocations were detected and identified by inverse polymerase chain reaction, followed by cloning and sequencing. Thirty-five patients (81%) presented putative translocations; among those, 91% corresponded with t(4;11) (q21;q23), while the other 9% corresponded with t(11;X), t(8;11)(q23;q23) and t(11;16). Our results indicate an increase in MLL aberrations in childhood ALL survivors years after completion of therapy. The higher frequency in this cohort might be associated with therapy using anti-tumoural drugs, independent of the inclusion of topoisomerase II inhibitors. Even though the biological significance of these rearrangements needs further investigation, they demonstrate a degree of genome instability, indicating the relevance of cytogenetic and molecular studies during the follow-up of patients in complete clinical remission.

Oncogenomic analysis of mycosis fungoides reveals major differences with Sezary syndrome

Mycosis fungoides (MF), the most common cutaneous T-cell lymphoma, is a malignancy of mature, skin-homing T cells. Sézary syndrome (Sz) is often considered to represent a leukemic phase of MF. In this study, the pattern of numerical chromosomal alterations in MF tumor samples was defined using array-based comparative genomic hybridization (CGH); simultaneously, gene expression was analyzed using microarrays. Highly recurrent chromosomal alterations in MF include gain of 7q36, 7q21-7q22 and loss of 5q13 and 9p21. The pattern characteristic of MF differs markedly from chromosomal alterations observed in Sz. Integration of data from array-based CGH and gene-expression analysis yielded several candidate genes with potential relevance in the pathogenesis of MF. We confirmed that the FASTK and SKAP1 genes, residing in loci with recurrent gain, demonstrated increased expression. The RB1 and DLEU1 tumor suppressor genes showed diminished expression associated with loss. In addition, it was found that the presence of chromosomal alterations on 9p21, 8q24, and 1q21-1q22 was associated with poor prognosis in patients with MF. This study provides novel insight into genetic alterations underlying MF. Furthermore, our analysis uncovered genomic differences between MF and Sz, which suggest that the molecular pathogenesis and therefore therapeutic requirements of these cutaneous T-cell lymphomas may be distinct.

Maintenance therapy in cutaneous T-cell lymphoma: Who, when, what?

The aim of current therapy for cutaneous T-cell lymphoma (CTCL) is to induce clinically meaningful remission, provide symptom relief, improve patient quality of life (QoL) and prolong disease-free and overall survival. A key research question is whether such remissions or minimal disease status can be maintained in the long term. There have been few formal studies of maintenance therapy in CTCL. Some skin-directed therapies such as total-skin electron-beam therapy and high-dose psoralen plus ultraviolet A may not be considered suitable, because of the risk of long-term cumulative toxicities. Other therapies such as nitrogen mustard, interferon (IFN)-alpha and bexarotene have demonstrated positive effects in prolonging remissions in small numbers of patients. Large longitudinal studies are required to investigate the efficacy of maintenance treatments in CTCL and their impact on patients' QoL and overall survival. Of the systemic therapies currently approved for the treatment of CTCL, bexarotene and IFN-alpha are obvious candidates for testing, because they can be self-administered by the patient and provide good long-term tolerability.

Absence of Microsatellite Instability and Lack of Evidence for Subclone Diversification in the Pathogenesis and Progression of Mycosis Fungoides

Mutator phenotypes with microsatellite instability (MSI) correlated with defects in the mismatch repair system are characteristic for a subset of solid neoplasms, but are rare in non-Hodgkin lymphomas. In mismatch repair-deficient mice, however, mutator-type non-Hodgkin lymphomas are the most frequent tumors. To determine the role of MSI in mycosis fungoides, we compared the states of the eight dinucleotide microsatellite loci DXS418, DXS453, DXS556, DXS1060, D1S201, D6S260, D9S162, and D10S215 in tumor cells of 12 well-characterized patients at early- and advanced-stage diseases to matched healthy tissue. We did not find any MSI, although all but one patient had progressed to advanced-stage disease within the timeframe of the study. Concordantly, the expression of mismatch repair genes was normal. These results suggest that progressive accumulation of mutations as detected by MS analysis does not play a major role in the pathogenesis or in the progression of mycosis fungoides.

Revisions to the staging and classification of mycosis fungoides and Sezary syndrome: a proposal of the International Society for Cutaneous Lymphomas (ISCL) and the cutaneous lymphoma task force of the European Organization of Research and Treatment of Cancer (EORTC)

The ISCL/EORTC recommends revisions to the Mycosis Fungoides Cooperative Group classification and staging system for cutaneous T-cell lymphoma (CTCL). These revisions are made to incorporate advances related to tumor cell biology and diagnostic techniques as pertains to mycosis fungoides (MF) and Sézary syndrome (SS) since the 1979 publication of the original guidelines, to clarify certain variables that currently impede effective interinstitution and interinvestigator communication and/or the development of standardized clinical trials in MF and SS, and to provide a platform for tracking other variables of potential prognostic significance. Moreover, given the difference in prognosis and clinical characteristics of the non-MF/non-SS subtypes of cutaneous lymphoma, this revision pertains specifically to MF and SS. The evidence supporting the revisions is discussed as well as recommendations for evaluation and staging procedures based on these revisions.

Spectral karyotyping demonstrates genetically unstable skin-homing T lymphocytes in cutaneous T-cell lymphoma

We initially established cell lines from skin biopsies from four patients (MF8, MF18, MF19 and MF31) in early stages of cutaneous T-cell lymphoma (CTCL) in 1999. After 3 weeks of culture, skin-homing T lymphocytes were stimulated with phytohaemagglutinin. Metaphase spreads were analysed using spectral karyotyping (SKY), a molecular cytogenetic technique. MF18 and MF19 had predominantly normal karyotypes. MF8 had recurrent numerical aberrations resulting in two T lymphocyte clones: one with trisomy 21 (12/20 cells) and the other with monosomy chromosome 22 (3/20 cells). MF8 also exhibited a clonal deletion, del(5)(p15.1), as well as multiple non-clonal structural aberrations. MF31 had a clonal deletion, del(17)(p12) and other non-clonal deletions involving chromosomes 2, 5, 10, 11. MF18 had a single abnormal cell that contained two reciprocal translocations t(1;2)(q32;p21) and t(4;10)(p15.2;q24). In 2001, three of the original patients had new skin biopsies taken and cell lines were established. SKY analysis revealed the continued presence of a T-cell clone in MF8 with trisomy 21 (4/20 cells). Additionally, a new clone was seen with a del(18)(p11.2) (17/20 cells). MF31 had only one aberrant cell with a del(17)(p12). MF18 had a clonal deletion, [del(1)(p36.1) in 3/20 cells] and non-clonal aberrations involving chromosomes 3, 4, 5, 6, 12, 13, 17 and 18. Thus, three of four patients continued to show numerous numerical and structural aberrations, both clonal and non-clonal, with only MF8 having a recurring T lymphocyte clone (+21). Our findings demonstrate high genetic instability among skin-homing T lymphocytes even in early stages of CTCL. We did not see genetic instability or evidence of clones in cell lines from a patient with atopic dermatitis and one with psoriasis.

Common chromosomal abnormalities in mycosis fungoides transformation

To identify cytogenetic features of large cell transformation in mycosis fungoides (T-MF), we selected in 11 patients, 16 samples either from skin tumors (13), lymph node (1), or peripheral blood cells (2) collected at the time of the transformation. Comparative genomic hybridization (CGH), G-banding, fluorescence in situ hybridisation (FISH), multicolour FISH (mFISH), and DNA content analysis were used. Fifteen samples displayed unbalanced CGH profiles, with gains more frequently observed than losses. Recurrent chromosomal alterations were observed for chromosomes 1, 2, 7, 9, 17, and 19. The most common imbalances were gain of chromosome regions 1p36, 7, 9q34, 17q24-qter, 19, and loss of 2q36-qter, 9p21, and 17p. In six samples 1p36-pter gain was associated with 9q34-qter gain and whole chromosome 19 gain. In five of these samples whole or partial gain of chromosome 17 was also observed. No specific pattern was seen with regard to the expression of the CD30 antigen by tumor cells. Cytogenetics and/or DNA content analysis of skin tumor cells revealed an abnormal chromosome number in all tested cases (n = 7) with DNA ploidy ranging from hyperdiploid (2.78) to hypotetraploid (3.69) (mean 3.14+/-0.38). Thus, T-MF displayed frequent chromosomal imbalances associated with hypotetraploidy.

Pathogenesis and therapy of cutaneous lymphomas--progress or impasse?

The cutaneous environment hosts a number of hematopoietic neoplasms that are dominated by primary cutaneous (PC) T-cell lymphomas. Recent progress in molecular biology and immunology has provided tools to investigate the pathogenesis and the biology of these neoplasms. This review highlights newest findings concerning the immune biology of CD4+ CD56+ hematodermic neoplasms, and PC T-cell and B-cell lymphomas, speculating how these can be translated into more sophisticated, biology-based treatment approaches in the near future.

New insights into the molecular biology and targeted therapy of cutaneous T-cell lymphomas

Cutaneous T-cell lymphoma is an extra-nodal non-Hodgkin lymphoma of mature T cells. These tumor cells home to and persist in the skin,producing a broad spectrum of clinical entities. Recent results of basic research on tumor biology and tumor immunology as well as molecular genetics of cutaneous T-cell lymphoma have fostered the development of new therapeutic approaches. Several clinical trials testing these targeted therapies have shown encouraging results. This article provides an overview of recent research developments and therapeutic strategies for cutaneous T-cell lymphoma.

Primary Cutaneous T-Cell Lymphomas Show a Deletion or Translocation AffectingNAV3, the HumanUNC-53Homologue

Multicolor fluorescent in situ hybridization (FISH) was used to identify acquired chromosomal aberrations in 12 patients with mycosis fungoides or Sézary syndrome, the most common forms of primary cutaneous T-cell lymphoma (CTCL). The most frequently affected chromosome was 12, which showed clonal deletions or translocations with a break point in 12q21 or 12q22 in five of seven consecutive Sézary syndrome patients and a clonal monosomy in the sixth patient. The break point of a balanced translocation t(12;18)(q21;q21.2), mapped in the minimal common region of two deletions, fine mapped to 12q2. By locus-specific FISH, the translocation disrupted one gene, NAV3 (POMFIL1), a human homologue of unc-53 in Caenorhabditis elegans. A missense mutation in the remaining NAV3 allele was found in one of six cases with a deletion or translocation. With locus-specific FISH, NAV3 deletions were found in the skin lesions of four of eight (50%) patients with early mycosis fungoides (stages IA-IIA) and in the skin or lymph node of 11 of 13 (85%) patients with advanced mycosis fungoides or Sézary syndrome. Preliminary functional studies with lentiviral small interfering RNA-based NAV3 silencing in Jurkat cells and in primary lymphocytes showed enhanced interleukin 2 expression (but not CD25 expression). Thus, NAV3 may contribute to the growth, differentiation, and apoptosis of CTCL cells as well as to the skewing from Th1-type to Th2-type phenotype during disease progression. NAV3, a novel putative haploinsufficient tumor suppressor gene, is disrupted in most cases of the commonest types of CTCL and may thus provide a new diagnostic tool.

A human T-cell lymphotropic virus type 1 enhancer of Myc transforming potential stabilizes Myc-TIP60 transcriptional interactions

The human T-cell lymphotropic virus type 1 (HTLV-1) infects and transforms CD4+ lymphocytes and causes adult T-cell leukemia/lymphoma (ATLL), an aggressive lymphoproliferative disease that is often fatal. Here, we demonstrate that the HTLV-1 pX splice-variant p30II markedly enhances the transforming potential of Myc and transcriptionally activates the human cyclin D2 promoter, dependent upon its conserved Myc-responsive E-box enhancer elements, which are associated with increased S-phase entry and multinucleation. Enhancement of c-Myc transforming activity by HTLV-1 p30II is dependent upon the transcriptional coactivators, transforming transcriptional activator protein/p434 and TIP60, and it requires TIP60 histone acetyltransferase (HAT) activity and correlates with the stabilization of HTLV-1 p30II/Myc-TIP60 chromatin-remodeling complexes. The p30II oncoprotein colocalizes and coimmunoprecipitates with Myc-TIP60 complexes in cultured HTLV-1-infected ATLL patient lymphocytes. Amino acid residues 99 to 154 within HTLV-1 p30II interact with the TIP60 HAT, and p30II transcriptionally activates numerous cellular genes in a TIP60-dependent or TIP60-independent manner, as determined by microarray gene expression analyses. Importantly, these results suggest that p30II functions as a novel retroviral modulator of Myc-TIP60-transforming interactions that may contribute to adult T-cell leukemogenesis.

A Retrospective Study of the Probability of the Evolution of Parapsoriasis en Plaques into Mycosis Fungoides

Parapsoriasis en plaque has been suggested to be an early manifestation of mycosis fungoides (cutaneous T-cell lymphoma). We explored the disease course of patients with small plaque or large plaque parapsoriasis in a 26-year retrospective cohort analysis of 105 parapsoriasis patients, who were clinically and histopathologically followed up in Helsinki and Tampere University Hospitals. Eventual later cancers of these patients were verified from the Finnish Cancer Registry. In the small plaque parapsoriasis group, 7 patients (10%) and in the large plaque parapsoriasis group 12 patients (35%), developed histologically confirmed mycosis fungoides during a median of 10 and 6 years, respectively. No significant differences were found regarding the risk of developing mycosis fungoides or the tendency to remission in patients treated with or without phototherapy. Our results show that not only large plaque parapsoriasis, but also small plaque parapsoriasis, as currently defined in textbooks, can progress to mycosis fungoides. The benefits of phototherapy are equivocal in parapsoriasis treatment as far as progression to cancer is concerned.

The genetics of skin cancer

Recent advances in molecular genetics have led to a better understanding of the biological underpinnings of skin cancer formation. As with most cancers, the RB, p53, and RAS pathways appear to play prominent roles in the pathogenesis of several skin cancer types. Although various components of these pathways may be differentially altered in squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and cutaneous melanoma, the final biochemical expression of these defects may be the same. With the unraveling of these genetic mechanisms, a more targeted approach to diagnosis and treatment may be possible in the near future.

Cellular coincidence of clonal T cell receptor rearrangements and complex clonal chromosomal aberrations-a hallmark of malignancy in cutaneous T cell lymphoma

Detection of a clonal T cell receptor (TCR) gene rearrangement is used in the diagnosis of primary cutaneous T cell lymphomas (CTCL) whereas chromosomal aberrations serve as a diagnostic tool for leukaemias and nodal lymphomas. To what extent both approaches specify the same cell population remains unknown. We investigated the coincidence of TCR clonality with complex clonal chromosomal aberrations, indicating qualitative alteration of the affected cells, in 17 CTCL patients. Out of 41 skin, blood, and lymph node samples studied, 34 gave results in chromosome and TCR analyses. With 88%, most specimens revealed corresponding results by both techniques (27 of 34 clonal, three of 34 non-clonal). In two patients, analysis of micro-dissected cells demonstrated that neoplastic T cells bear both a dominant TCR rearrangement and a complex chromosomal aberration. The cutaneous clone was found in blood samples of 11 of 12 patients (including early stages), and investigation of follow-up skin and blood samples indicated persistence of the T cell clone in 11 of 14 cases. In conclusion, we show that dominant TCR clones and chromosomal clones converge in all stages of CTCL. These clones disseminate into blood and skin at early disease stages and persist despite therapy. The coexistence of a dominant TCR clone and a clonal chromosomal aberration can thus be used as a hallmark of malignancy.