Inactivation of tumor suppressor genes p15(INK4b) and p16(INK4a) in primary cutaneous B cell lymphoma

Obesity and Risk for Lymphoma: Possible Role of Leptin

Obesity, which is considered a pandemic due to its high prevalence, is a risk factor for many types of cancers, including lymphoma, through a variety of mechanisms by promoting an inflammatory state. Specifically, over the last few decades, obesity has been suggested not only to increase the risk of lymphoma but also to be associated with poor clinical outcomes and worse responses to different treatments for those diseases. Within the extensive range of proinflammatory mediators that adipose tissue releases, leptin has been demonstrated to be a key adipokine due to its pleotropic effects in many physiological systems and diseases. In this sense, different studies have analyzed leptin levels and leptin/leptin receptor expressions as a probable bridge between obesity and lymphomas. Since both obesity and lymphomas are prevalent pathophysiological conditions worldwide and their incidences have increased over the last few years, here we review the possible role of leptin as a promising proinflammatory mediator promoting lymphomas.

CUTANEOUS B-CELL LYMPHOMAS: UPDATE ON DIAGNOSIS, RISK-STRATIFICATION, AND MANAGEMENT

PCBCLs are a group of Non-Hodgkin's B-cell lymphomas originating in and usually confined to the skin, representing approximately one fourth of primary cutaneous lymphomas (PCL). Their current classification system has been the result of the joint World Health Organization (WHO) - European Organization for Research and Treatment of Cancer (EORTC) consensus in 2018. To date, several types of PCBCLs have been described in the scientific literature, with different clinical presentation and prognosis. Primary cutaneous follicle-center lymphoma (PCFCL) and primary cutaneous marginal zone lymphoma (PCMZL) are the most common forms, with a typical indolent course. On the contrary, primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL, LT) is less common, yet more aggressive, with a reported 5-year overall survival of approximatively 50%. In this review, we outline the PCBCLs defining diagnostic criteria, report the features of the less common subtypes and summarize the noteworthy therapeutical options currently available in this field.

Diagnosis and Management of Cutaneous B-Cell Lymphomas

Primary cutaneous B-cell lymphomas are a group of diseases with indolent and aggressive behavior. The goal of the initial workup is to evaluate for systemic involvement, provide adequate staging, and guide therapy. Histopathological studies are a critical part of the workup for classification of these lymphomas because they are similar to their nodal counterparts. There are limited data for treatment guidelines, and thus, therapy differs among institutions. Overall, localized therapies are preferred for indolent types and chemotherapy or immunotherapy for the aggressive forms.

Primary cutaneous B-cell lymphoma: narrative review of the literature

Primary cutaneous B-cell lymphomas comprehend a group of lymphoproliferative disorders characterized by being monoclonal proliferations of B-cell primarily involving the skin. Despite being recognized as autonomous and distinct clinico-pathologic entities since the late 80s, their classification is still an ongoing matter of debate. At the moment, WHO classification recognizes three disorders: primary cutaneous marginal zone lymphoma, primary cutaneous follicle center lymphoma and primary cutaneous diffuse large b-cell lymphoma (leg type). Primary cutaneous diffuse large b-cell lymphoma (other) has been used to define rare cases which show histologically an infiltrate with diffuse pattern composed by large b-cell, but not fitting with criteria for follicle center lymphoma nor for primary cutaneous diffuse large b-cell lymphoma (leg type). Aim of this review was to briefly describe all recognized and provisional entities included in the primary cutaneous b-cell lymphomas and to discuss recent acquisitions that may influence their future classifications.

A Literature Revision in Primary Cutaneous B-cell Lymphoma

The term “Primary Cutaneous B-Cell Lymphoma” (PCBCL) comprehends a variety of lymphoproliferative disorders characterized by a clonal proliferation of B-cells primarily involving the skin. The absence of evident extra-cutaneous disease must be confirmed after six-month follow-up in order to exclude a nodal non-Hodgkin's lymphoma (NHL) with secondary cutaneous involvement, which may have a completely different clinical behavior and prognosis. In this article, we have summarized the clinico-pathological features of main types of PCBCL and we outline the guidelines for management based on a review of the available literature.

Primary cutaneous follicle center lymphoma associated with an extracutaneous dissemination: a cytogenetic finding of potential prognostic value

OBJECTIVES

Cytogenetic studies on cutaneous lymphomas are rare, and very little is known about their prognostic value. We present a rare case of primary cutaneous follicle center lymphoma (PCFCL) with a complex translocation presenting with cutaneous and extracutaneous dissemination in the lymph node.

METHODS

Morphologic, immunohistochemical, conventional cytogenetic, and fluorescence in situ hybridization (FISH) studies were performed on this patient.

RESULTS

A combination of cytogenetic and FISH analysis identified a complex novel four-way t(2;14;9;3) (p11.2;q32;p13;q27) translocation involving rearrangements of BCL6, immunoglobulin light and heavy chain genes, and an unknown gene on 9p.

CONCLUSIONS

Our report elaborates the morphologic and immunohistochemical features in combination with cytogenetic and molecular cytogenetic analysis of PCFCL, which provide additional insight into the clinical and biologic behavior of this lesion.

Radiotherapy of primary cutaneous follicle center lymphoma: case report and review of literature

Primary cutaneous follicle center lymphoma is an indolent primary cutaneous B-cell lymphoma originating from the follicle center cells, composed of a combination of centrocytes (small and large cleaved cells) and centroblasts (large noncleaved cells) with a follicular, follicular/diffuse, or diffuse growth pattern. Lesions are mostly located on the head, neck and trunk. A case is presented of a 56-year-old male patient with primary cutaneous follicle center lymphoma, with lesions involving the skin of the back, shoulders, presternal area and right forearm. As the patient presented a disseminated cutaneous form of the disease that involved several anatomical regions, complete work-up was followed by superficial fractionated radiotherapy of eight fields in VI expositions, with total irradiation dose of 1400 cGy upon the following fields: right and left pectoral region, left and right shoulders, right suprascapular region, and proximal third of the right forearm. Total irradiation dose applied upon each field for the lesions located on the left and right side of the back was 1500 cGy. This therapy resulted in significant reduction of visible tumor. The patient was regularly followed up on outpatient basis for 12 months of radiotherapy, being free from local recurrence and systemic spread of the disease.

Simultaneous aberrations of single CDKN2A network components and a high Rb phosphorylation status can differentiate subgroups of primary cutaneous B-cell lymphomas

The cyclin-dependent kinase inhibitor 2A (CDKN2A) gene on chromosome 9p21 encodes p16 (INK4A), the inhibitor of the CDK4/retinoblastoma (Rb) cell proliferation pathway, as well as p14 (ARF), which controls p53-dependent pathways. Inactivation of p16 has previously been associated with the prognostically unfavourable primary cutaneous diffuse large B-cell lymphoma, leg type (PCLBCL, LT). In this work, we analysed 22 tumors [nine primary cutaneous follicle centre lymphomas (PCFCL), seven primary cutaneous marginal zone lymphomas (PCMZL) and six PCLBCL, LT] not only for alterations of the p16 gene but also for p14, p53 and Rb by fluorescence in situ hybridization (FISH) and immunohistochemistry. In most PCLBCL, LT (4/6) alterations of CDKN2A (two biallelic deletions, one monoallelic deletion and one trisomy 9) and in addition the highest frequency of deletions of p53 (3/6) and Rb (3/6) were detected. p16 was not expressed but very high levels of phosphorylated Rb, indicating a functional effect of genomic CDKN2A alterations on the protein level in PCLBCL, LT. Regarding the p14/p53 axis, PCLBCL, LT showed a variable expression. Neither PCFCL nor PCMZL showed alterations of CDKN2A and also deletions of p53 or Rb were extremely rare in these subtypes. Exclusively in PCMZL, p53 protein was consistently lacking. In conclusion, only PCLBCL, LT is characterized by a high frequency of aberrations of the CDKN2A network components in both important tumor suppressor pathways regulated by the CDKN2A gene. Moreover, PCLBCL, LT appears to be distinguishable from PCMZL not only by its level of p53 expression but also by its stage of Rb phosphorylation. The latter may also apply to a subgroup of PCFCL.

Prognostic significance of p14ARF, p15INK4b, and p16INK4a inactivation in malignant peripheral nerve sheath tumors

PURPOSE

p14(ARF), p15(INK4b), and p16(INK4a) are tumor suppressor genes that are located closely at 9p21 and are often coinactivated by genetic or epigenetic alterations. Malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma with poor prognosis. However, the prognostic implications of inactivation of p14(ARF), p15(INK4b), and p16(INK4a) in MPNSTs have not been adequately investigated. Here we carried out a genetic, epigenetic, and expression analysis of p14(ARF), p15(INK4b), and p16(INK4a), and clarified the prognostic significance of their inactivation in MPNSTs.

EXPERIMENTAL DESIGN

p14(ARF), p15(INK4b), and p16(INK4a) protein expressions were assessed by immunohistochemistry in 129 formalin-fixed samples of MPNST including 85 primary tumors. Thirty-nine samples, for which frozen material was available, were also investigated by Western blotting and quantitative reverse transcription PCR (RT-PCR) to detect p14(ARF), p15(INK4b), and p16(INK4a) protein and mRNA expression, and by multiplex real-time PCR, PCR single strand conformation polymorphism and methylation-specific PCR to detect p14(ARF), p15(INK4b), and p16(INK4a) gene alterations.

RESULTS

Immunohistochemically decreased expressions of p14(ARF), p15(INK4b), and p16(INK4a) were observed in 48%, 54%, and 49% of primary MPNSTs, respectively, and were significantly correlated with their concordant mRNA levels. As for gene alterations, homozygous deletion of CDKN2A was detected in one third of the cases. Inactivation of p14(ARF) and p16(INK4a) was associated with poor prognosis by both univariate and multivariate analyses. Furthermore, cases with inactivation of all p14(ARF), p15(INK4b), and p16(INK4a) genes showed the worst prognosis in a combined prognostic assessment.

CONCLUSION

A comprehensive analysis of p14(ARF), p15(INK4b), and p16(INK4a) inactivation status provides useful prognostic information in MPNSTs.

Polymerase chain reaction-based clonality analysis of cutaneous B-cell lymphoproliferative processes

INTRODUCTION

The differential diagnosis of B-cell lymphoproliferative processes remains a challenge for pathologists, dermatologists and oncologists, despite advances in histology, immunohistochemistry and molecular biology.

OBJECTIVE

Evaluate aid and limitations of clonality analysis in the diagnosis of primary cutaneous B-cell lymphomas and B-cell pseudolymphomas.

METHODS

This study included 29 cases of B-cell lymphoproliferative processes classified as primary cutaneous B-cell lymphomas (13), B-cell pseudolymphomas (6) and inconclusive cases (10) using histology and immunohistochemistry. The clonality analysis was performed by polymerase chain reaction analysis of immunoglobulin light chain and heavy chain rearrangements.

RESULTS

DNA quality was shown to be generally poor; eight samples were inadequate for polymerase chain reaction analysis. The results showed monoclonality in eight of the primary cutaneous B-cell lymphomas and polyclonality in four of the B-cell pseudolymphomas. In addition, monoclonality was shown in two of the inconclusive cases by histology and immunohistochemistry, demonstrating the utility of polymerase chain reaction as an ancillary diagnostic tool for primary cutaneous B-cell lymphomas.

DISCUSSION

The low quality DNA extracted from these cases demanded the use of an IgH protocol that yielded small fragments and IgK. Both methods used together improved detection.

CONCLUSION

Use of the two protocols, immunoglobulin heavy chain FR3-trad and immunoglobulin light chain-Kappa Biomed protocols for clonality analysis improved diagnostic accuracy.

Aberrant DNA methylation in skin diseases

Epigenetic mechanisms are involved in regulating cell growth and differentiation without inducing changes in the gene sequence. The main epigenetic mechanisms include DNA methylation, histone modification, and microRNA. Recent studies indicate that aberrant DNA methylation is a common feature of many human disorders, including cancer, autoimmune diseases, heart diseases, skin diseases, and others. Skin diseases comprise various diseases that have a complex etiology and pathogenesis, including genetics and acquired factors such as environment and diet. These acquired factors often have pathogenic effects through modification of DNA and histones, of which DNA methylation is the most common mechanism. Aberrant DNA methylation has been demonstrated in skin diseases, including skin tumors and autoimmune-related skin disorders. Herein, we review the role of DNA methylation in the pathogenesis of skin diseases.

Epigenetics and dermatological disease

Epigenetics is the study of differences in phenotype, in the absence of variation in the genetic code. Epigenetics is relevant in the pathogenesis of many skin diseases. In the case of the common skin cancers, aberrant methylation of tumor suppressor gene promoters is associated with their transcriptional inactivation. Environmental carcinogens such as ultraviolet radiation and arsenic may act through epigenetic mechanisms. Hypomethylation is associated with activation of systemic autoimmune diseases, such as systemic lupus erythematosus, subacute cutaneous lupus erythematosus and scleroderma. This may be through a mechanism of immunological cross-reactivity with hypomethylated DNA from pathogenic bacteria. Epigenetic factors may also be relevant in the pathogenesis of psoriasis and other inflammatory skin diseases, as well as in the pathogenesis of the disorders of genomic imprinting with cutaneous features.

Mycosis fungoides and Sézary syndrome

Mycosis fungoides and Sézary syndrome are the most common of the cutaneous T-cell lymphomas, which are a heterogeneous group of neoplasms that affect the skin as a primary site. Although the aetiologies of mycosis fungoides and Sézary syndrome are unknown, important insights have been gained in the immunological and genetic perturbations that are associated with these diseases. Unlike some B-cell lymphomas, cutaneous T-cell lymphomas as a group are rarely if ever curable and hence need chronic-disease management. New approaches to treatments are being investigated and include biological and cytotoxic drugs, phototherapy, and monoclonal antibodies that are directed towards novel molecular targets. New molecular technologies such as complementary-DNA microarray have the potential to increase the accuracy of diagnosis and provide important prognostic information. Treatments can be combined to greatly improve clinical outcome without substantially increasing toxic effects in advanced disease that is otherwise difficult to treat. Although present treatment strategies are generally not curative, there is hope that experimental treatments, particularly immunotherapy, might eventually reverse or suppress the abnormalities of mycosis fungoides and Sézary syndrome to the point at which they become non-life-threatening, chronic diseases.

Interrelationships among chromosome aneuploidy, promoter hypermethylation, and protein expression of the CDKN2A gene in individuals from northern Brazil with gastric adenocarcinoma

Numerical alterations of chromosome 9, the status of promoter methylation and protein expression of the CDKN2A gene (aliases include p16 and p16(INK4a)), the possible association with gain of chromosome X, and the interrelation of these findings with clinic and pathological characteristics were investigated in gastric adenocarcinomas. Fluorescence in situ hybridization analysis with centromeric DNA probes, immunohistochemical staining, and methylation-specific polymerase chain reaction assays were performed in 15 gastric adenocarcinomas samples from individuals from northern Brazil. Aneuploidies of chromosomes X and 9 were found in all samples, both intestinal and diffuse type. Monosomy of chromosome 9 and gain of a copy of chromosome X (in both sexes) were observed in 100% of cases. Hypermethylation frequency and protein expression of CDKN2A were also found in all cases analyzed. No association of genetic and epigenetic alterations with histological type, tumor aggressiveness, and invasion was found (P > 0.05), which may be attributable to small sample size. There was a high level of association between absence of p16 protein expression levels, CDKN2A gene promote hypermethylation, and chromosome 9 aneuploidy (100% of cases). Thus, in the present samples, the apparent mechanisms behind p16 silencing include loss of chromosome 9 and promoter region hypermethylation.

p16(CDKN2) gene polymorphism: association with histologic subtypes of epithelial ovarian cancer in China

p16 is an important tumor suppressor gene, which is inactivated in many kinds of tumors. The common variants of p16 may be associated with the risk of certain tumors development. We analyzed the frequency of two adjacent polymorphisms in p16 exon 3 (540C-->G and 580C-->T) and their haplotype in blood samples from epithelial ovarian cancer (EOC) patients and healthy controls using polymerase chain reaction-restriction fragment length polymorphism. The results showed that the genotype frequency of p16 580C-->T polymorphism was significantly different among histologic subtypes of EOC (P= 0.02). T allele carriers significantly reduced the risk of serous EOC; the adjusted odds ratio was 0.40 (95% CI = 0.19-0.84). There are neither association between p16 540C-->G polymorphism and EOC development, progression, nor association between the haplotypes of two single nucleotide polymorphisms and the tumor development. Our results suggested that the p16 580C-->T polymorphism might affect the individual susceptibility to specific subtypes of EOC. Different types of ovarian cancer might adopt distinct carcinogenetic pathways. However, this result may be further validated in a larger sample of patients.

Loss of p16 in recurrent malignant mixed müllerian tumors of the uterus

Uterine malignant mixed müllerian tumors (MMMTs) are rare and highly aggressive malignancies with poor clinical prognoses. We examined for differences in the oncoprotein profiles of primary versus recurrent MMMTs. Five cases of recurrent uterine MMMT were examined by paraffin immunohistochemistry for the expression of p53, p16, P-cadherin, and Cerb-B2. P16, p53, and P-cadherin were each expressed in 100%, 80%, and 60% of the primary cases, respectively. Three cases expressed all three oncoproteins. All five cases were negative for Cerb-B2. No difference in antigen expression was seen in the epithelial versus sarcomatous components. Primary and recurrent tumors were concordant for p53, P-cadherin, and Cerb-B2. However, three cases of recurrent tumors were negative for p16 expression. P53, p16, and P-cadherin are common tumor suppressor genes expressed in uterine MMMT. Interestingly, p16 protein expression was lost in some cases of MMMTs when they recurred. This suggests that the oncoprotein and possibly genetic profile of p16 changes over time. We did not observe any difference in antigen expression between areas of epithelial or sarcomatous differentiation, which would support a single pluripotential malignant clone in the histogenesis of these tumors.

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.

Update on extranodal lymphomas. Conclusions of the Workshop held by the EAHP and the SH in Thessaloniki, Greece

Classification and proper treatment of extranodal lymphoma is hindered by the diversity of lymphoma types and the relative rarity of many of these tumour types. In order to review controversial issues in extranodal lymphoma diagnosis, a joint Workshop of the European Haematopathology Association (EAHP) and the Society for Hematopathology (SH) was held, where 99 selected cases were reviewed and discussed. This Workshop summary is focused on the most controversial aspect of cutaneous B-cell lymphoma, other extranodal B-cell lymphomas, plasmablastic lymphoma and anaplastic large-cell lymphoma in extranodal sites, and makes practical recommendations about diagnosis and therapeutic approaches.

The new World Health Organization-European Organization for Research and Treatment of Cancer classification for cutaneous lymphomas: a practical marriage of two giants

Following consensus meetings of the two parent organizations, a new World Health Organization-European Organization for Research and Treatment of Cancer (WHO-EORTC) classification for primary cutaneous lymphomas has recently been published. This important development will now end the ongoing debate as to which of these was the preferred classification. The new classification will facilitate more uniformity in diagnosis, management and treatment of cutaneous lymphomas. In particular, it provides a useful distinction between indolent and more aggressive types of primary cutaneous lymphoma and provides practical advice on preferred management and treatment regimens. This will thereby prevent patients receiving high-grade treatment for low-grade biological disease. This review focuses on those diseases which have found new consensus agreement compared with the original WHO and EORTC classifications. In cutaneous T-cell lymphomas, these include folliculotropic mycosis fungoides, defining features of Sézary syndrome, primary cutaneous CD30+ lymphoproliferative disorders (primary cutaneous anaplastic large cell lymphoma, lymphomatoid papulosis and borderline lesions) and subcutaneous panniculitis-like T-cell lymphoma. Primary cutaneous CD4+ small/medium-sized pleomorphic T-cell lymphoma, primary cutaneous aggressive epidermotropic CD8+ T-cell lymphoma and cutaneous gamma/delta T-cell lymphoma are allocated provisional entry status and thereby afford better definitions for some cases of currently unspecified primary cutaneous peripheral T-cell lymphoma. In cutaneous B-cell lymphomas, diseases which have found new consensus agreement include primary cutaneous marginal zone B-cell lymphoma, primary cutaneous follicular centre lymphoma, primary cutaneous diffuse large B-cell lymphoma, leg type and primary cutaneous diffuse large B-cell lymphoma, other. CD4+/CD56+ haematodermic neoplasm (early plasmacytoid dendritic cell leukaemia/lymphoma) now appears as a precursor haematological neoplasm and replaces the previous terminology of blastic NK-cell lymphoma. Other haematopoietic and lymphoid tumours involving the skin, as part of systemic disease, will appear in the forthcoming WHO publication Tumours of the Skin. The new classification raises interesting new problems and questions about primary cutaneous lymphoma and some of these are discussed in this article. It is, however, a splendid signpost indicating the direction in which research in cutaneous lymphoma needs to go. In the interim, we have an international consensus classification which is clinically meaningful.

WHO/EORTC classification of cutaneous lymphomas 2005: histological and molecular aspects

The new WHO/EORTC classification for cutaneous lymphomas comprises mature T-cell and natural killer (NK)-cell neoplasms, mature B-cell neoplasms, and immature hematopoietic malignancies. It reflects the unique features of lymphoproliferative diseases of the skin, and at the same time it is as compatible as possible with the concepts underlying the WHO classification for nodal lymphomas and the EORTC classification of cutaneous lymphomas. This article reviews the histological, phenotypical, and molecular genetic features of the various nosological entities included in this new classification. These findings always have to be interpreted in the context of the clinical features and biologic behavior.

AIM

To review the histological, phenotypical and molecular genetic features of the various nosological entities of the new WHO/EORTC classification for cutaneous lymphomas.

METHODS

Extensive review of the literature cited in Medline and own data of the authors.

RESULTS

The WHO/EORTC classification of cutaneous lymphomas comprises mature T-cell and NK-cell neoplasms, mature B-cell neoplasms and immature hematopoietic malignancies. It reflects the unique features of primary cutaneous lymphoproliferative diseases.

CONCLUSION

This classification is as much as possible compatible with the concept of the WHO classification for nodal lymphomas and the EORTC classification of cutaneous lymphomas. The histological, phenotypical and molecular genetic features always have to be interpreted in the context of the clinical features and biologic behavior.

Array-based comparative genomic hybridization analysis reveals recurrent chromosomal alterations and prognostic parameters in primary cutaneous large B-cell lymphoma

PURPOSE

To evaluate the clinical relevance of genomic aberrations in primary cutaneous large B-cell lymphoma (PCLBCL).

PATIENTS AND METHODS

Skin biopsy samples of 31 patients with a PCLBCL classified as either primary cutaneous follicle center lymphoma (PCFCL; n = 19) or PCLBCL, leg type (n = 12), according to the WHO-European Organisation for Research and Treatment of Cancer (EORTC) classification, were investigated using array-based comparative genomic hybridization, fluorescence in situ hybridization (FISH), and examination of promoter hypermethylation.

RESULTS

The most recurrent alterations in PCFCL were high-level DNA amplifications at 2p16.1 (63%) and deletion of chromosome 14q32.33 (68%). FISH analysis confirmed c-REL amplification in patients with gains at 2p16.1. In PCLBCL, leg type, most prominent aberrations were a high-level DNA amplification of 18q21.31-q21.33 (67%), including the BCL-2 and MALT1 genes as confirmed by FISH, and deletions of a small region within 9p21.3 containing the CDKN2A, CDKN2B, and NSG-x genes. Homozygous deletion of 9p21.3 was detected in five of 12 patients with PCLBCL, leg type, but in zero of 19 patients with PCFCL. Complete methylation of the promoter region of the CDKN2A gene was demonstrated in one PCLBCL, leg type, patient with hemizygous deletion, in one patient without deletion, but in zero of 19 patients with PCFCL. Seven of seven PCLBCL, leg type, patients with deletion of 9p21.3 and/or complete methylation of CDKN2A died as a result of their lymphoma.

CONCLUSION

Our results demonstrate prominent differences in chromosomal alterations between PCFCL and PCLBCL, leg type, that support their classification as separate entities within the WHO-EORTC scheme. Inactivation of CDKN2A by either deletion or methylation of its promoter could be an important prognostic parameter for the group of PCLBCL, leg type.

Aberrant DNA Methylation in Cutaneous Malignancies

In recent years it has become evident that in addition to genetic mutations also epigenetic alterations are causally related to the development and progression of cancer. The epigenetic mechanism most relevant in the pathogenesis of cancer appears to be aberrant methylation of tumor-suppressor gene promoters associated with transcriptional downregulation. Malignancies arising in the skin are the most prevalent in humans. The most common are basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (SCC), melanoma, and cutaneous lymphoma. The visibility and accessibility of cutaneous tumors facilitate the scientific study of sequential epigenetic alterations occurring during tumorigenesis and might make treatment of malignant skin lesions using locally applied demethylating agents possible. In this review, we summarize the current knowledge concerning alterations of DNA methylation in BCC, SCC, melanoma, and cutaneous lymphoma. Furthermore, the potential "epigenotoxic" effects of ultraviolet radiation, an environmental carcinogen implicated in the tumorigenesis of most cutaneous malignancies, will be discussed. From the limited number of investigations of promoter hypermethylation in cutaneous malignancies, it is already clear that a great number of potential tumor-suppressor genes are epigenetically silenced in skin cancer, including components of signaling pathways critical in the pathogenesis of these malignancies.

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.

Distinct types of primary cutaneous large B-cell lymphoma identified by gene expression profiling

In the European Organization for Research and Treatment of Cancer (EORTC) classification 2 types of primary cutaneous large B-cell lymphoma (PCLBCL) are distinguished: primary cutaneous follicle center cell lymphomas (PCFCCL) and PCLBCL of the leg (PCLBCL-leg). Distinction between both groups is considered important because of differences in prognosis (5-year survival > 95% and 52%, respectively) and the first choice of treatment (radiotherapy or systemic chemotherapy, respectively), but is not generally accepted. To establish a molecular basis for this subdivision in the EORTC classification, we investigated the gene expression profiles of 21 PCLBCLs by oligonucleotide microarray analysis. Hierarchical clustering based on a B-cell signature (7450 genes) classified PCLBCL into 2 distinct subgroups consisting of, respectively, 8 PCFCCLs and 13 PCLBCLsleg. PCLBCLs-leg showed increased expression of genes associated with cell proliferation; the proto-oncogenes Pim-1, Pim-2, and c-Myc; and the transcription factors Mum1/IRF4 and Oct-2. In the group of PCFCCL high expression of SPINK2 was observed. Further analysis suggested that PCFCCLs and PCLBCLs-leg have expression profiles similar to that of germinal center B-cell-like and activated B-cell-like diffuse large B-cell lymphoma, respectively. The results of this study suggest that different pathogenetic mechanisms are involved in the development of PCFCCLs and PCLBCLs-leg and provide molecular support for the subdivision used in the EORTC classification.

Epigenetic Inactivation of Tumor Suppressor Genes in Hematologic Malignancies

A number of genetic alterations are involved in the development of hematologic malignancies. These alterations include the activation of oncogenes by chromosomal translocation or gene amplification and the inactivation of tumor suppressor genes by gene deletion or mutations. Recently, epigenetic change has been proven to be another important means of inactivating tumor suppressor genes in tumor cells, and hypermethylation of promoter DNA is one of the most important mechanisms. In hematologic malignancies, many kinds of tumor suppressor genes and candidate suppressor genes are epigenetically inactivated. Inactivation of tumor suppressor genes usually occurs in a disease-specific manner and plays important roles in the development and progression of the disease. Some of these alterations have clinical effects on treatment results or the prognoses of the patients.

Promoter hypermethylation and protein expression of the p16 gene: analysis of 43 cases of B-cell primary gastric lymphomas from China

The p16 (CDKN2a/INK4a) gene is an important tumor-suppressor gene, involved in the p16/cyclin-dependent kinase/retinoblastoma gene pathway of cell cycle control. The p16 protein is considered to be a negative regulator of the pathway. Promoter hypermethylation resulting in inactivation of the p16 gene has been found in various hematopoietic malignancies, including non-Hodgkin's lymphoma, and may play a role in transformation/clinical aggressiveness of those tumors. However, the p16 protein expression in primary gastric lymphoma has not been studied. In this study, we characterize protein expression and promoter hypermethylation of the p16 gene in B-cell primary gastric lymphomas from China. In all, 43 cases of B-cell primary gastric lymphoma were investigated. They consisted of 24 (56%) cases of diffuse large-cell lymphoma, 12 (28%) cases of extranodal marginal zone lymphoma, six (14%) cases of extranodal marginal zone lymphoma with large-cell transformation and one (2%) case of follicular lymphoma. Loss of p16 protein expression was found in 34 (79%) out of 43 cases, while the remaining nine (21%) cases showed positivities for the p16 protein. All 43 cases were further characterized by methylation-specific polymerase chain reaction (PCR) to analyze p16 promoter hypermethylation status. In total, 11 (26%) of 43 cases were positive for p16 promoter hypermethylation. Among those, 10 (30%) out of the 33 cases negative for the p16 immunostaining showed promoter hypermethylation, whereas only one (10%) out of the 10 cases that were positive for the p16 immunostaining displayed promoter hypermethylation. Of the 43 cases, 30 had limited pathologic data at the time of resection. Primary gastric lymphoma involved extragastric sites (lymph node or liver) in 17 (57%) of 30 cases, while the remaining 13 (43%) cases were only limited to the stomach. Loss of p16 protein expression was found in 14 (82%) of 17 cases with extragastric involvement and in 11 (85%) of 13 cases without such involvement. In conclusion, loss of p16 protein expression is frequent in those B-cell primary gastric lymphomas and approximately one-third of such loss correlated with promoter hypermethylation. Despite limited pathologic data, loss of p16 protein expression appears not to be correlated with extragastric involvements.

Inhibitors of DNA methylation in the treatment of hematological malignancies and MDS

DNA methylation abnormalities have recently emerged as one of the most frequent molecular changes in hematopoietic neoplasms. Since methylation and transcriptional status are inversely correlated, the hypermethylation of genes involved in cell-cycle control and apoptosis could have a pathogenetic role in the development of cancer. In particular, high-risk myelodysplastic syndromes (MDS) and secondary leukemias show a high prevalence of tumor suppressor gene hypermethylation. The progression of chronic myeloproliferative diseases and of myelodysplastic syndromes, as well as that of lymphoproliferative diseases, is associated with an increased methylation rate, pointing to a role for hypermethylation of critical promoter regions in the transformation to more aggressive phenotypes. In the same line, a significantly worse prognosis has been shown for patients with hypermethylation of several genes compared to that of patients with unmethylated genes. For these reasons, the use of irreversible DNA methyltransferase inhibitors, such as 5-azacytidine and Decitabine, appears to be a promising option for the treatment of MDS and acute myeloid leukemia. In clinical trials, Azacytidine results in a significantly higher response rate, improved quality of life, reduced risk of leukemic transformation, and improved survival compared to supportive care. Similarly, Decitabine showed favorable results, promising response rates, a good nonhematologic toxicity profile, and a trend for better survival compared to intensive chemotherapy, particularly in older patients. The synergistic effect of histone deacetylase inhibitors, including phenylbutyrate (PB), in reactivating silenced genes encouraged clinical studies on the combination of PB and demethylating agents in hematological diseases, characterized by p15 silencing. The sequential administration of a "first generation" demethylating agent and HDAC inhibitors gave preliminary evidence of a reduced methylation of target genes, as also described with Decitabine. Clinical trials are still ongoing, and preliminary data indicate for the first time that the natural history of MDS may be changed by a non-intensive treatment, characterized by an outstanding toxicity profile.

Primary cutaneous B-cell lymphomas: a practical approach

PCBCL are a heterogeneous group of B-cell lymphomas that originate in the skin, with the absence of extracutaneous disease at diagnosis. Overall, these cutaneous lymphomas have an excellent prognosis. Recurrences are common but dissemination is rare. The EORTC classification allows a more uniform diagnosis and treatment of patients with PCBCL. Careful clinical and pathologic correlation is critical in confirming a diagnosis of PCBCL, before deciding on therapy. Several therapeutic options that are aimed at cure, are available. In most instances, chemotherapy should not be the first line of treatment.

Primary cutaneous lymphomas: a review with current treatment options

Primary cutaneous T- and B-cell lymphomas are a heterogenous group of diseases with varied clinical presentations and prognosis. The use of new molecular, histological, and clinical criteria have enhanced the recognition of primary cutaneous T- and B-cell lymphomas. Compared to their nodal counterpart they have a different clinical behavior and therefore require a different treatment approach. Independent predictive factors identified clinically, histologically, and by immunopheno- and immunogenotyping are essential to assess the appropriate treatment for each subtype. The European Organization for Research and Treatment of Cancer (EORTC) Cutaneous Lymphoma Study Group provide a classification of cutaneous lymphomas taking into account of the histological and molecular features. Based on this classification we will provide a summary of the current medical literature in diagnosis, treatment, and prognosis for primary cutaneous lymphomas with emphasis on new treatment strategies.

Frequent copresence of methylated DNA and fragmented nucleosomal DNA in plasma of lymphoma patients

BACKGROUND

The circulating DNA in plasma/serum of cancer patients has been shown to reflect the characteristics of the tumor DNA including molecular changes, such as methylation, point mutations and microsatellite instability. Fragmented nucleosomal DNA in plasma resulting from apoptotic death of the tumor cells may also provide an indication for tumor DNA. In this study, we comparatively analysed plasma DNA methylation and presence of fragmented nucleosomal DNA in patients with lymphoproliferative diseases.

METHODS

Methylation in the first exon of the tumor supressor gene p16 was investigated by the methylation-sensitive restriction enzyme-related PCR. DNA fragmentation in plasma was analysed by gel electrophoresis.

RESULTS

p16 gene methylation was found to occur in 73% of patients but in none of the 20 healthy controls. Nucleosomal DNA fragmentation was detectable in 81% of patients. In 67% of patients, copresence of both parameters was observed. Presence of both parameters was associated with the stage of disease which was more pronounced for nucleosomal DNA fragmentation.

CONCLUSIONS

Our results suggest that presence of methylated and apoptotic DNA in plasma of patients with lymphoproliferative diseases is a frequent event and may be used as a marker for early diagnosis and during the follow-up of the disease.

Analysis of promoter hypermethylation of death-associated protein kinase and p16 tumor suppressor genes in actinic keratoses and squamous cell carcinomas of the skin

Death-associated protein kinase is a serine/threonine protein kinase implicated in promoting apoptosis and tumor suppression, whereas p16 is a tumor suppressor gene that inhibits cyclin-dependent kinase 4 and 6 activity and arrests the cell cycle in the G1 phase. Hypermethylation of death-associated protein kinase or p16 gene with resultant gene inactivation has been described in a wide variety of human cancers. Promoter methylation of the death-associated protein kinase and p16 gene has been found in about 55% and 30% cases of head and neck squamous cell carcinoma respectively but has not yet been analyzed in cutaneous premalignant and malignant lesions. A total of 33 cases were examined for evidence of death-associated protein kinase and p16 hypermethylation and these consist of 9 cases of spongiotic dermatitis as nonneoplastic skin control, 9 cases of actinic keratosis, 8 cases of squamous cell carcinoma in situ, and 7 cases of invasive squamous cell carcinoma. Death-associated protein kinase promoter methylation was detected in 1 case of squamous cell carcinoma in situ and 1 case of nonneoplastic skin control but none of the cases of invasive squamous cell carcinoma or actinic keratosis. P16 promoter methylation was detected in 1 case of invasive squamous cell carcinoma and 1 case of nonneoplastic skin control but none of the cases of squamous cell carcinoma in situ or actinic keratosis. Promoter hypermethylation of the death-associated protein kinase and p16 genes does not appear to play an important role in the development of cutaneous squamous cell carcinoma. The data thus suggest that the mechanisms of ultraviolet-induced cutaneous carcinomas differ from those involved in the development of head and neck squamous cell carcinoma, a malignant disease induced by tobacco and alcohol exposure.

Mutational analysis of CDKN2A genes in patients with squamous cell carcinoma of the skin

BACKGROUND

Nonmelanoma skin cancers [squamous cell carcinomas (SCC) and basal cell carcinomas (BCC)] are the most common neoplasias of the Caucasian population.

OBJECTIVES

The purpose of our study was to determine the involvement of CDKN2A genes in the development of sporadic nonmelanoma skin cancer in Greek patients.

PATIENTS AND METHODS

Allelic imbalance analysis was performed in 22 SCC and five Bowen's disease specimens. Mutational analysis was performed on exons 1alpha, 1beta and 2 of the CDKN2A locus in 22 SCC, five Bowen's disease and 39 BCC specimens. Exon 1alpha was additionally screened in 28 BCC specimens to complete the mutational analysis of a previous study.

RESULTS

Overall, 52% (14 of 27) of the SCC and Bowen's disease specimens exhibited loss of heterozygosity (LOH) in at least one microsatellite marker, whereas, only two of 27 (7%) exhibited microsatellite instability. LOH in 9p appears to be equally involved in both BCC and SCC tumours. Exons 1alpha, 1beta and 2 of the CDKN2A locus were screened for mutations. A Val28Gly substitution in exon 1alpha and a CCC-->TTT (Ala57Val and Arg58Ter) substitution in exon 2, resulting in a change in the amino acid sequence, are reported for the first time in two SCCs, the latter being indicative of a combination of an ultraviolet (UV) radiation-induced mutation and a point mutation. A previously described polymorphism of CDKN2A, the gene for p16INK4a, Ala148Thr, was also detected in an allelic frequency of 3.72%. No mutation was found in any of the five Bowen's disease specimens, or in exon 1beta of CDKN2A, also the gene for p14ARF.

CONCLUSIONS

Mutations and the high incidence of 9p LOH detected in our SCC samples imply that inactivation of CDKN2A genes, via allelic loss and/or mutation (probably UV-induced) may play a significant role in nonmelanoma skin cancer development, particularly in the more aggressive SCC type.

Amplification and overexpression of JUNB is associated with primary cutaneous T-cell lymphomas

Primary cutaneous lymphomas (PCLs) represent a heterogeneous group of extranodal T- and B-cell malignancies. The underlying molecular pathogenesis of this malignancy remains unclear. This study aimed to characterize oncogene abnormalities in PCLs. Using genomic microarray, we detected oncogene copy number gains of RAF1 (3p25), CTSB (8p22), PAK1 (11q13), and JUNB (19p13) in 5 of 7 cases of mycosis fungoides (MF)/Sezary syndrome (SS) (71%), gains of FGFR1 (8p11), PTPN (20q13), and BCR (22q11) in 4 cases (57%), and gains of MYCL1 (1p34), PIK3CA (3q26), HRAS (11p15), MYBL2 (20q13), and ZNF217 (20q13) in 3 cases (43%). Amplification of JUNB was studied in 104 DNA samples from 78 PCL cases using real-time polymerase chain reaction. Twenty-four percent of cases, including 7 of 10 cases of primary cutaneous CD30(+) anaplastic large-cell lymphoma (C-ALCL), 4 of 14 MF, 4 of 22 SS, and 2 of 23 primary cutaneous B-cell lymphoma (PCBCL) showed amplification of JUNB, and high-level amplification of this oncogene was present in 3 C-ALCL and 2 MF cases. JUNB protein expression was analyzed in tissue sections from 69 PCL cases, and 44% of cases, consisting of 21 of 23 SS, 6 of 8 C-ALCL, 5 of 10 MF, and 9 of 21 PCBCL, demonstrated nuclear expression of JUNB by tumor cells. Overexpression of JUNB also was detected in 5 C-ALCL and 2 SS cases. These results have revealed, for the first time, amplification and expression patterns of JUNB in PCL, suggesting that JUNB may be critical in the pathogenesis of primary cutaneous T-cell lymphomas.

Effects of p16 gene on biological behavious in hepatocellular carcimoma cells

AIM: To investigate the effects of p16 gene on biological behavious in hepatocellular carcinoma cells.

METHODS: HCC cell lines SNU-449 and HepG2.2.15 were infected respectively by a replication defective, recombinant retrovirus capable of producing a high level of p16 protein expression (pCLXSN-p16). G418 resistant stable p16 protein expression cell lines were selected. And the biological behaviours of the p16 gene transfected HCC cells were observed.

RESULTS: Initial in vitro experiments in HCC cell line SNU-449 with loss of p16 protein expression demonstrated the pCLXSN-p16 treatment significantly inhibited cell growth. But there was no treatment effect when the pCLXSN-p16 was used in another HCC cell line HepG2.2.15 which has positive p16 protein expression. Subsequent study in a nude mouse model demonstrated that the p16 gene transfected SNU-449 had a lower succeeding rate in the first time establishment of tumors and grew more slowly in the nude mice when compared with non-transfected SNU-449. Moreover, the nude mice inoculated with transfected SNU-449 had a longer surviving time than those inoculated with non-transfected SNU-449.

CONCLUSION: Our results show that the p16INK4a gene transfer can inhibit the proliferation and reduce the invasion ability of hepatocellular carcinoma.