Histologic and epidemiologic correlates of P-MAPK, Brn-2, pRb, p53, and p16 immunostaining in cutaneous melanomas

The contemporary management of cancers of the sinonasal tract in adults

Sinonasal malignancies make up <5% of all head and neck neoplasms, with an incidence of 0.5-1.0 per 100,000. The outcome of these rare malignancies has been poor, whereas significant progress has been made in the management of other cancers. The objective of the current review was to describe the incidence, causes, presentation, diagnosis, treatment, and recent developments of malignancies of the sinonasal tract. The diagnoses covered in this review included sinonasal undifferentiated carcinoma, sinonasal adenocarcinoma, sinonasal squamous cell carcinoma, and esthesioneuroblastoma, which are exclusive to the sinonasal tract. In addition, the authors covered malignances that are likely to be encountered in the sinonasal tract-primary mucosal melanoma, NUT (nuclear protein of the testis) carcinoma, and extranodal natural killer cell/T-cell lymphoma. For the purpose of keeping this review as concise and focused as possible, sarcomas and malignancies that can be classified as salivary gland neoplasms were excluded.

Immunohistochemical Expression of p16 in Melanocytic Lesions: An Updated Review and Meta-analysis

CONTEXT

- Making an accurate diagnosis for melanocytic lesions has always been challenging for pathologists, especially when dealing with difficult-to-diagnose cases. Misdiagnosis of melanoma and melanocytic lesions in general has tremendous medical-legal implications, often leading to unnecessary and excessive use of adjunctive tests. Although molecular testing is of much interest and there is great support for its development, currently, for most melanocytic lesions, immunohistochemical studies remain the most practical method for assistance in the routine diagnosis of melanocytic lesions for the average pathologist.

OBJECTIVES

- To review the practical use of p16 immunohistochemistry for evaluating melanocytic lesions, particularly for differentiating benign from malignant tumors, and to perform a meta-analysis of primary studies evaluating p16 immunohistochemistry in melanocytic lesions.

DATA SOURCES

- A PubMed database search for literature reporting melanocytic lesions and p16 immunohistochemistry was performed. Essential information from each study (number of samples, antibody used, collection dates, overall p16 immunohistochemistry results, and general method of interpretation) was tabulated and analyzed. Examples of representative cases showing p16 immunostaining pattern are also illustrated.

CONCLUSIONS

- Incorporation of p16 immunohistochemistry for the diagnosis of melanocytic lesions is of limited use, especially for the purpose of differentiating benign from malignant lesions. Evaluation of multiple studies reveals a wide range of results. However, there appears to be some value for the use of p16 in distinguishing nodal nevi from metastatic melanoma within nodes. The method of interpretation (nuclear versus cytoplasmic staining) also appears to give differing results, as studies considering only nuclear staining appeared to show more consistent results from study to study.

BRN2 suppresses apoptosis, reprograms DNA damage repair, and is associated with a high somatic mutation burden in melanoma

Herbert et al. show that BRN2 is associated with DNA damage response proteins and suppresses an apoptosis-associated gene expression program to protect against UVB-, chemotherapy-, and vemurafenib-induced apoptosis.

Whether cell types exposed to a high level of environmental insults possess cell type-specific prosurvival mechanisms or enhanced DNA damage repair capacity is not well understood. BRN2 is a tissue-restricted POU domain transcription factor implicated in neural development and several cancers. In melanoma, BRN2 plays a key role in promoting invasion and regulating proliferation. Here we found, surprisingly, that rather than interacting with transcription cofactors, BRN2 is instead associated with DNA damage response proteins and directly binds PARP1 and Ku70/Ku80. Rapid PARP1-dependent BRN2 association with sites of DNA damage facilitates recruitment of Ku80 and reprograms DNA damage repair by promoting Ku-dependent nonhomologous end-joining (NHEJ) at the expense of homologous recombination. BRN2 also suppresses an apoptosis-associated gene expression program to protect against UVB-, chemotherapy- and vemurafenib-induced apoptosis. Remarkably, BRN2 expression also correlates with a high single-nucleotide variation prevalence in human melanomas. By promoting error-prone DNA damage repair via NHEJ and suppressing apoptosis of damaged cells, our results suggest that BRN2 contributes to the generation of melanomas with a high mutation burden. Our findings highlight a novel role for a key transcription factor in reprogramming DNA damage repair and suggest that BRN2 may impact the response to DNA-damaging agents in BRN2-expressing cancers.

Intratumor and Intertumor Heterogeneity in Melanoma

Melanoma is a cancer that exhibits one of the most aggressive and heterogeneous features. The incidence rate escalates. A high number of clones harboring various mutations contribute to an exceptional level of intratumor heterogeneity of melanoma. It also refers to metastases which may originate from different subclones of primary lesion. Such component of the neoplasm biology is termed intertumor and intratumor heterogeneity. These levels of tumor heterogeneity hinder accurate diagnosis and effective treatment. The increasing number of research on the topic reflects the need for understanding limitation or failure of contemporary therapies. Majority of analyses concentrate on mutations in cancer-related genes. Novel high-throughput techniques reveal even higher degree of variations within a lesion. Consolidation of theories and researches indicates new routes for treatment options such as targets for immunotherapy. The demand for personalized approach in melanoma treatment requires extensive knowledge on intratumor and intertumor heterogeneity on the level of genome, transcriptome/proteome, and epigenome. Thus, achievements in exploration of melanoma variety are described in details. Particularly, the issue of tumor heterogeneity or homogeneity given BRAF mutations is discussed.

MAP Kinase Pathways: Molecular Roads to Primary Acral Lentiginous Melanoma

The etiology and pathogenesis of lentiginous acral melanomas are poorly understood. Recent studies have postulated that DNA repair mechanisms and cell growth pathways are involved in the development of melanoma, particularly changes in the MAPK pathways (RAS, BRAF, MEK 1/2, and ERK 1/2). The aim of this study is to assess the status of the MAP kinase pathways in the pathogenesis of acral melanomas. The authors examined the components of the RAS–RAF–MEK–ERK cascades by immunohistochemistry in a series of 16 primary acral melanomas by tissue microarray. The expression of MAP kinase cascade proteins changed in most cases. The authors observed that 57.14% of cases were BRAF positive and that 61.53%, 71.42%, and 71.42% of cases were positive for MEK2, ERK1, and ERK2, respectively; RAS was not expressed in 92.31%, and all cases were negative for MEK1. The absence of RAS and positivity for MEK2, ERK1, and ERK2 were most seen in invasive cases with high thickness. These aspects of the MAPK pathway require further examination in acral melanomas between different populations. Nevertheless, the results highlight significant alterations in the MAP kinase cascades that are related to histological indicators of prognosis in primary acral melanomas.

Immunohistochemical evaluation of p16 expression in cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions

BACKGROUND

Expression of p16 is frequently evaluated in melanocytic lesions. Expression of p16 in cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions has not been well characterized.

METHODS

We evaluated p16 expression in a cohort of histiocytic (reticulohistiocytoma, Langerhans cell histiocytosis, xanthogranuloma, Rosai Dorfman disease and xanthoma), fibrohistiocytic (dermatofibroma, epithelioid fibrous histiocytoma and dermatofibrosarcoma protuberans) and undifferentiated (atypical fibroxanthoma and pleomorphic undifferentiated sarcoma) lesions. A group of melanocytic lesions (Spitz nevus, ordinary nevus, spitzoid melanoma and non-spitzoid melanoma) were also evaluated as reference. Each case was scored by the proportion of p16-positive cells and by staining intensity.

RESULTS

Immunoreactivity for p16 was found in almost all histiocytic (28/30, 93%) and fibrohistiocytic (22/24, 92%) lesions. About half of the undifferentiated lesions also exhibited p16 staining (9/17, 53%). Most of the melanocytic cases examined in this study expressed p16. A wide range of staining intensity and proportion of p16-positive cells was observed in most groups.

CONCLUSION

Expression of p16 is common, albeit variable in proportion and intensity, amongst a wide variety of cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions. Further studies are required to determine if p16 expression is useful in distinguishing benign from malignant neoplasms of these types.

Association Between NRAS and BRAF Mutational Status and Melanoma-Specific Survival Among Patients With Higher-Risk Primary Melanoma

IMPORTANCE

NRAS and BRAF mutations in melanoma inform current treatment paradigms, but their role in survival from primary melanoma has not been established. Identification of patients at high risk of melanoma-related death based on their primary melanoma characteristics before evidence of recurrence could inform recommendations for patient follow-up and eligibility for adjuvant trials.

OBJECTIVE

To determine tumor characteristics and survival from primary melanoma by somatic NRAS and BRAF status.

DESIGN, SETTING, AND PARTICIPANTS

A population-based study with a median follow-up of 7.6 years (through 2007), including 912 patients from the United States and Australia in the Genes, Environment, and Melanoma (GEM) Study, with first primary cutaneous melanoma diagnosed in the year 2000 and analyzed for NRAS and BRAF mutations.

MAIN OUTCOMES AND MEASURES

Tumor characteristics and melanoma-specific survival of primary melanoma by NRAS and BRAF mutational status.

RESULTS

The melanomas were 13% NRAS+, 30% BRAF+, and 57% with neither NRAS nor BRAF mutation (wildtype [WT]). In a multivariable model including clinicopathologic characteristics, relative to WT melanoma (with results reported as odds ratios [95% CIs]), NRAS+ melanoma was associated with presence of mitoses (1.8 [1.0-3.3]), lower tumor-infiltrating lymphocyte (TIL) grade (nonbrisk, 0.5 [0.3-0.8]; and brisk, 0.3 [0.5-0.7] [vs absent TILs]), and anatomic site other than scalp/neck (0.1 [0.01-0.6] for scalp/neck vs trunk/pelvis), and BRAF+ melanoma was associated with younger age (ages 50-69 years, 0.7 [0.5-1.0]; and ages >70 years, 0.5 [0.3-0.8] [vs <50 years]), superficial spreading subtype (nodular, 0.5 [0.2-1.0]; lentigo maligna, 0.4 [0.2-0.7]; and unclassified/other, 0.2 [0.1-0.5] [vs superficial spreading]), and presence of mitoses (1.7 [1.1-2.6]) (P < .05 for all). There was no significant difference in melanoma-specific survival (reported as hazard ratios [95% CIs]) for melanoma harboring mutations in NRAS (1.7 [0.8-3.4]) or BRAF (1.5 [0.8-2.9]) compared with WT melanoma, as adjusted for age, sex, site, American Joint Committee on Cancer (AJCC) tumor stage, TIL grade, and study center. However, melanoma-specific survival was significantly poorer for higher-risk (T2b or higher stage) tumors with NRAS (2.9 [1.1-7.7]) or BRAF (3.1 [1.2-8.5]) mutations (P = .04) but not for lower-risk (T2a or lower) tumors with NRAS (0.9 [0.3-3.0]) or BRAF (0.6 [0.2-1.7]) (P = .65), as adjusted for age, sex, site, AJCC tumor stage, TIL grade, and study center.

CONCLUSIONS AND RELEVANCE

Lower TIL grade for NRAS+ melanoma suggests it has a more immunosuppressed microenvironment, which may affect its response to immunotherapies. The approximate 3-fold increased risk of death for higher-risk tumors harboring NRAS or BRAF mutations after adjusting for other prognostic factors compared with WT melanomas indicates that the prognostic implication of these mutations deserves further investigation, particularly in higher–AJCC stage primary melanomas.

Update on primary head and neck mucosal melanoma

Primary mucosal melanomas (PMMs) of the head and neck are uncommon malignancies that arise mainly in the nasal cavity and paranasal sinuses, followed by the oral cavity. The mainstay of treatment is radical surgical resection followed by adjuvant radiotherapy in selected patients with high-risk features. Multimodality therapy has not been well studied and is not standardized. Adjuvant radiotherapy seems to improve locoregional control but does not improve overall survival (OS). Elective neck dissection is advocated in patients with oral PMM. Systemic therapy should be considered only for patients with metastatic or unresectable locoregional disease. Despite improvements in the field of surgery, radiotherapy, and systemic therapy, patients with PMM still face a very unfavorable prognosis (5-year disease-free survival [DFS] <20%) with high rates of locoregional recurrence and distant metastasis. The present review aims to summarize the current state of knowledge on the molecular biology, pathological diagnosis, and management of this disease.

[HPV (Human Papilloma Virus) implication in other cancers than gynaecological]

Worldwide, approximately 5 to 10% of the population is infected by a Human Papilloma Virus (HPV). Some of these viruses, with a high oncogenic risk (HPV HR), are responsible for about 5% of cancer. It is now accepted that almost all carcinomas of the cervix and the vulva are due to an HPV HR (HPV16 and 18) infection. However, these viruses are known to be involved in the carcinogenesis of many other cancers (head and neck [SCCHN], penis, anus). For head and neck cancer, HPV infection is considered as a good prognostic factor. The role of HPV HR in anal cancer is also extensively studied in high-risk patient's population. The role of HPV infection in the carcinogenesis of esophageal, bladder, lung, breast or skin cancers is still debated. Given the multiple possible locations of HPV HR infection, the question of optimizing the management of patients with a HPV+ cancer arises in the implementation of a comprehensive clinical and biological monitoring. It is the same in therapeutics with the existence of a preventive vaccination, for example.

p16 (INK4a) has clinicopathological and prognostic impact on oropharynx and larynx squamous cell carcinoma

CDKN2A encodes proteins such as p16 (INK4a), which negatively regulate the cell-cycle. Molecular genetic studies have revealed that deletions in CDKN2A occur frequently in cancer. Although p16 (INK4a) may be involved in tumor progression, the clinical impact and prognostic implications in head and neck squamous cell carcinoma (HNSCC) are controversial. The objective of this study was to evaluate the frequency of the immunohistochemical expression of p16 (INK4a) in 40 oropharynx and 35 larynx from HNSCC patients treated in a single institution and followed-up at least for 10 years in order to explore potential associations with clinicopathological outcomes and prognostic implications. Forty cases (53.3%) were positive for p16 (INK4a) and this expression was more intense in non-smoking patients (P = 0.050), whose tumors showed negative vascular embolization (P = 0.018), negative lymphatic permeation (P = 0.002), and clear surgical margins (P = 0.050). Importantly, on the basis of negative p16 (INK4a) expression, it was possible to predict a probability of lower survival (P = 0.055) as well as tumors presenting lymph node metastasis (P = 0.050) and capsular rupture (P = 0.0010). Furthermore, increased risk of recurrence was observed in tumors presenting capsular rupture (P = 0.0083). Taken together, the alteration in p16 (INK4a) appears to be a common event in patients with oropharynx and larynx squamous cell carcinoma and the negative expression of this protein correlated with poor prognosis.

Molecular dermatopathology in malignant melanoma

At present, immunohistochemistry is taken for granted in the establishment of malignant melanoma (MM) diagnosis. In recent years, molecular diagnosis in dermatopathology has benefited from a vast array of advances in the fields of genomics and proteomics. Sensitive techniques are available for detecting specific DNA and RNA sequences by molecular hybridization. This paper intends to update methods of molecular cytogenetics available as diagnostic adjuncts in the field of MM. Cytogenetics has highlighted the pathogenesis of atypical melanocytic neoplasms with emphasis on the activation of the mitogen-activated protein kinase (MAPK) signalling pathway during the initiation step of the neoplasms. 20 to 40% of MM families have mutations in the tumour suppressor gene p16 or CDKN2A. In addition, somatic mutations in p16, p53, BRAF, and cKIT are present in MM. Genome-wide scan analyses on MM indicate positive associations for genes involved in melanocytic naevi, but MM is likely caused by a variety of common low-penetrance genes. Molecular dermatopathology is expanding, and its use in the assessment of melanocytic neoplasms appears to be promising in the fields of research and diagnosis. Molecular dermatopathology will probably make its way to an increased number of diagnostic laboratories. The expected benefit should improve the patient management. This evolution points to a need for evolution in the training requirements and role of dermatopathologists.

Inverse expression states of the BRN2 and MITF transcription factors in melanoma spheres and tumour xenografts regulate the NOTCH pathway

The use of adherent monolayer cultures have produced many insights into melanoma cell growth and differentiation, but often novel therapeutics demonstrated to act on these cells are not active in vivo. It is imperative that new methods of growing melanoma cells that reflect growth in vivo are investigated. To this end, a range of human melanoma cell lines passaged as adherent cultures or induced to form melanoma spheres (melanospheres) in stem cell media have been studied to compare cellular characteristics and protein expression. Melanoma spheres and tumours grown from cell lines as mouse xenografts had increased heterogeneity when compared with adherent cells and 3D-spheroids in agar (aggregates). Furthermore, cells within the melanoma spheres and mouse xenografts each displayed a high level of reciprocal BRN2 or MITF expression, which matched more closely the pattern seen in human melanoma tumours in situ, rather than the propensity for co-expression of these important melanocytic transcription factors seen in adherent cells and 3D-spheroids. Notably, when the levels of the BRN2 and MITF proteins were each independently repressed using siRNA treatment of adherent melanoma cells, members of the NOTCH pathway responded by decreasing or increasing expression, respectively. This links BRN2 as an activator, and conversely, MITF as a repressor of the NOTCH pathway in melanoma cells. Loss of the BRN2-MITF axis in antisense-ablated cell lines decreased the melanoma sphere-forming capability, cell adhesion during 3D-spheroid formation and invasion through a collagen matrix. Combined, this evidence suggests that the melanoma sphere-culture system induces subpopulations of cells that may more accurately portray the in vivo disease, than the growth as adherent melanoma cells.

Expression of HERV-K correlates with status of MEK-ERK and p16INK4A-CDK4 pathways in melanoma cells

The dysregulated ERK and RB pathways often coexist in melanoma cells. The K-type human endogenous retrovirus (HERV-K) is implicated in melanomagenesis. Some of the phenotypes that are modified by HERV-K (e.g., changes in cell shape, melanin production, and anchorage-dependent growth) overlap with those that are regulated by ERK and RB pathways. As ERK signaling can regulate retroviruses, we hypothesized that HERV-K expression is controlled by ERK-RB pathways. We found that the levels of HERV-K GAG and EVE correlated with the activation of ERK and loss of p16INK4A and that inhibition of MEK or CDK4, especially in combination, reduced HERV-K EVE in melanoma cells.

The association between MC1R genotype and BRAF mutation status in cutaneous melanoma: findings from an Australian population

There is increasing epidemiological and molecular evidence that cutaneous melanomas arise through multiple causal pathways. The purpose of this study was to explore the relationship between germline and somatic mutations in a population-based series of melanoma patients to reshape and refine the divergent pathway model for melanoma. Melanomas collected from 123 Australian patients were analyzed for melanocortin-1 receptor (MC1R) variants and mutations in the BRAF and NRAS genes. Detailed phenotypic and sun exposure data were systematically collected from all patients. We found that BRAF-mutant melanomas were significantly more likely from younger patients and those with high nevus counts, and were more likely in melanomas with adjacent neval remnants. Conversely, BRAF-mutant melanomas were significantly less likely in people with high levels of lifetime sun exposure. We observed no association between germline MC1R status and somatic BRAF mutations in melanomas from this population. BRAF-mutant melanomas have different origins from other cutaneous melanomas. These data support the divergent pathways hypothesis for melanoma, which may require a reappraisal of targeted cancer prevention activities.