Diagnostic value of microtubule-associated protein-2 in Merkel cell carcinoma

Expression of the microtubule-associated protein 2 (MAP2) as a potential independent prognostic marker in prostate cancer

PURPOSE

Investigation of Microtubuli-associated Protein 2 (MAP2) expression and its clinical relevance in prostate cancer.

MATERIAL AND METHODS

MAP2 expression was immunohistochemically analysed on radical prostatectomy specimens using whole block sections (n = 107) and tissue microarrays (TMA; n = 310). The staining intensity was evaluated for carcinoma, benign tissue and prostatic intraepithelial neoplasia. Expression data were correlated with clinicopathological parameters and biochemical recurrence-free survival. Additionally, MAP2 protein expression was quantitatively analysed in the serum of histologically confirmed prostate carcinoma patients and the control group using a commercial enzyme-linked immunosorbent assay.

RESULTS

MAP2 staining was significantly stronger in neoplastic tissue than in non-neoplastic prostatic glands, both in whole block sections (p < 0.01) and in TMA sections (p < 0.05). TMA data revealed significantly stronger MAP2 staining in high-grade tumors. Survival analysis showed a significant correlation between strong MAP2 staining in carcinoma and shortened biochemical recurrence-free survival after prostatectomy (p < 0.001). Multivariate Cox regression analysis confirmed MAP2 as an independent predictor for an unfavourable course. Mean MAP2 serum levels for non-PCA vs. PCA patients differed significantly (non-PCA = 164.7 pg/ml vs. PCA = 242.5 pg/ml, p < 0.001).

CONCLUSION

The present data support MAP2 as a novel biomarker in PCA specimens. MAP2 is correlated with tumor grade and MAP2 high-expressing PCA is associated with an increased risk of biochemical recurrence after radical prostatectomy. Future studies are necessary to evaluate MAP2 as a valuable immunohistochemical biomarker in preoperative PCA diagnostic procedures, in particular with regard to treatment modalities.

Characterizing DNA methylation signatures and their potential functional roles in Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a rare but aggressive skin cancer with limited treatment possibilities. Merkel cell tumors display with neuroendocrine features and Merkel cell polyomavirus (MCPyV) infection in the majority (80%) of patients. Although loss of histone H3 lysine 27 trimethylation (H3K27me3) has been shown during MCC tumorigenesis, epigenetic dysregulation has largely been overlooked.

METHODS

We conducted global DNA methylation profiling of clinically annotated MCC primary tumors, metastatic skin tumors, metastatic lymph node tumors, paired normal tissues, and two human MCC cell lines using the Illumina Infinium EPIC DNA methylation BeadArray platform.

RESULTS

Significant differential DNA methylation patterns across the genome are revealed between the four tissue types, as well as based on MCPyV status. Furthermore, 964 genes directly regulated by promoter or gene body DNA methylation were identified with high enrichment in neuro-related pathways. Finally, our findings suggest that loss of H3K27me3 occupancy in MCC is attributed to KDM6B and EZHIP overexpression as a consequence of promoter DNA hypomethylation.

CONCLUSIONS

We have demonstrated specific DNA methylation patterns for primary MCC tumors, metastatic MCCs, and adjacent-normal tissues. We have also identified DNA methylation markers that not only show potential diagnostic or prognostic utility in MCC management, but also correlate with MCC tumorigenesis, MCPyV expression, neuroendocrine features, and H3K27me3 status. The identification of DNA methylation alterations in MCC supports the need for further studies to understand the clinical implications of epigenetic dysregulation and potential therapeutic targets in MCC.

Intrinsic and Extrinsic Factors Affecting Microtubule Dynamics in Normal and Cancer Cells

Microtubules (MTs), highly dynamic structures composed of α- and β-tubulin heterodimers, are involved in cell movement and intracellular traffic and are essential for cell division. Within the cell, MTs are not uniform as they can be composed of different tubulin isotypes that are post-translationally modified and interact with different microtubule-associated proteins (MAPs). These diverse intrinsic factors influence the dynamics of MTs. Extrinsic factors such as microtubule-targeting agents (MTAs) can also affect MT dynamics. MTAs can be divided into two main categories: microtubule-stabilizing agents (MSAs) and microtubule-destabilizing agents (MDAs). Thus, the MT skeleton is an important target for anticancer therapy. This review discusses factors that determine the microtubule dynamics in normal and cancer cells and describes microtubule–MTA interactions, highlighting the importance of tubulin isoform diversity and post-translational modifications in MTA responses and the consequences of such a phenomenon, including drug resistance development.

The expression of terminal deoxynucleotidyl transferase and paired box gene 5 in Merkel cell carcinomas and its relation to the presence of Merkel cell polyomavirus DNA

BACKGROUND

Merkel cell carcinoma (MCC) tumor samples frequently express B-lymphoid lineage markers. However, the reasons for expression of specific B-lymphoid lineage markers are still unclear. We studied the expression of TdT and PAX5 (two B-cell lymphoid lineage markers) in a large pool of MCC tissue microarray samples.

METHODS

Immunoexpression and staining intensities of TdT and Pax-5 were statistically correlated with patient, tumor, Merkel cell polyomavirus (MCV), and disease-specific parameters.

RESULTS

In a cohort of 117 MCC patients and their corresponding tumor samples, TdT was expressed in 37 (31.6%) samples and PAX5 in 26 (22.2%). Simultaneous immunostaining for TdT and PAX5 was observed in 13 (11.1%) samples. A statistically significant relationship was observed between MCV virus copy number and positive TdT expression (P = 0.0056). Similarly, a significant relationship was also observed between positive TdT and tumor MCV virus positivity (P = 0.000495).

CONCLUSION

We observed frequent TdT and PAX5 immunoexpression in MCC tumor samples. However, simultaneous immunoexpression of these markers was scarce. TdT expression was statistically significantly associated with MCV positivity. The absence of a statistically significant association between tumor parameters and disease progression markers undermines the systemic use of these markers in clinical practice.

Regulation of paclitaxel activity by microtubule-associated proteins in cancer chemotherapy

Microtubules, highly dynamic components of the cytoskeleton, participate in diverse cellular activities such as mitosis, cell migration, and intracellular trafficking. Dysregulation of microtubule dynamics contributes to the development of serious diseases, including cancer. The dynamic properties and functions of microtubule network are regulated by microtubule-associated proteins. Paclitaxel, an anti-microtubule agent of the taxane family, has shown a success in clinical treatment of many cancer patients. However, the variable response activity of patients and acquired resistance to paclitaxel limit the clinical use of the drug. Accumulating studies show that microtubule-associated proteins can regulate paclitaxel sensitivity in a wide range of cancer types. In this review, we will describe the roles of various microtubule-associated proteins in the regulation of paclitaxel in cancers. Particularly, we will focus on the modulation of centrosomal proteins in paclitaxel resistance. Improved understandings of how these proteins act might predict treatment responses and provide insights into more rational chemotherapeutic regimens in clinical practice.

Utility of CD99 Paranuclear Expression in the Differential Diagnosis of Merkel Cell Carcinoma

Background. Recent reviews have referred to the paranuclear dot-like staining pattern of CD99 in several neoplasms, including solid pseudopapillary tumors in the pancreas, colonic adenocarcinomas, and colonic adenomas as well as in Merkel cell carcinoma (MCC). The aim of this work was to explore the utility of CD99 paranuclear staining in the differential diagnosis of MCC. Material and Methods. We explore paranuclear dot-like CD99 expression in several small, round blue cell neoplasms, including neuroendocrine neoplasms, Ewing sarcomas/primitive neuroectodermal tumors (EWS/PNET), melanomas, small cell lung carcinomas (SCC), lymphoblastic lymphoma/leukemia, and rhabdomyosarcomas, in comparison with 33 cases of MCC, to determine the specificity of the paranuclear dot-like CD99 expression in MCC. Results. Twenty MCC (60%) demonstrated focal expression of CD99 and of those, 14 (42.4%) showed the characteristic paranuclear dot-like expression. CD99 was also paranuclear positive in 4 of 11 (36%) SCC, in 3 of 7 (43%) EWS/PNET, in 1 of 6 (16%) lymphoblastic lymphoma/leukemia cases, in 3 of 3 (100%) rhabdomyosarcomas and all melanomas were negative for the CD99 reaction. Conclusion. CD99 paranuclear dot-like expression was not exclusive of the MCC compared with several neoplasms included in its differential diagnosis. This expression is not a great diagnostic aid.

Merkel cell carcinoma. A review

BACKGROUND

Merkel cell carcinoma (MCC) is a rare potentially fatal skin tumour affecting older mainly white people and younger immunosuppressed individuals. While uncommon, the incidence is increasing relative to melanoma and with twice the lethality. The benign appearance of the tumour usually on exposed skin parts, contrasting with its extensive microscopic invasion, can delay timely diagnosis. Recurrent MCC is currently attributed to the recently discovered Merkel cell polyomavirus This brief review of MCC covers the history, epidemiology,etiology,clinical and histological features, treatment and prognosis.

METHODS

Literature search using PubMed and search words Merkel cell carcinoma (MCC), etiology, treatment for the years 1972 to 2010.

RESULTS AND CONCLUSION

Merkel cell carcinoma is a rare malignancy with uncertain prognosis. Due to the uncommon occurrence and dearth of randomized studies, there is no agreement on optimal treatment. The tumor has only recently been included in the international classification of tumors (NCCN). The treatment approaches found to be best are radical surgery of primary tumor, drainage of lymph node extension and possibly adjuvant loco-regional radiotherapy. The basis of successful treatment however, remains prevention regular dermatological examination in immunosuppressed patients and early initiation of combination therapy, based on radical surgery supplemented by radiotherapy and palliative chemotherapy in the last resort.

Increased expression of MAP2 inhibits melanoma cell proliferation, invasion and tumor growth in vitro and in vivo

Malignant melanoma (MM) is characterized by aggressive metastasis and high mortality rate. Microtubule-associated proteins 2 (MAP2) is expressed abundantly in majority of melanocytic nevi and primary melanomas, but absent in metastatic melanomas. To determine whether MAP2 correlates with tumor progression of MM, we investigated the effects of MAP2 inhibition on the biological behaviour of metastatic melanoma in vitro and in vivo. Our results demonstrated that adenovirus-mediated MAP2 induced apoptotic cell death and cell cycle arrest in metastatic human and mouse melanoma cell lines in vitro, and substantially inhibited the growth of melanomas in nude mice in vivo. In addition, intracellular expression of MAP2 was found to induce the morphologic alteration, suppress the migration and invasion and affect the assembly, stabilization and bundling of microtubules in melanoma cells. This is the first study that MAP2 expression significantly inhibits the growth of MM in vivo. Our results suggest that MAP2 may serve as a promising molecular target for therapy and chemoprevention of MM in humans.

Identification of markers of taxane sensitivity using proteomic and genomic analyses of breast tumors from patients receiving neoadjuvant paclitaxel and radiation

PURPOSE

To identify molecular markers of pathologic response to neoadjuvant paclitaxel/radiation treatment, protein and gene expression profiling were done on pretreatment biopsies.

EXPERIMENTAL DESIGN

Patients with high-risk, operable breast cancer were treated with three cycles of paclitaxel followed by concurrent paclitaxel/radiation. Tumor tissue from pretreatment biopsies was obtained from 19 of the 38 patients enrolled in the study. Protein and gene expression profiling were done on serial sections of the biopsies from patients that achieved a pathologic complete response (pCR) and compared to those with residual disease, non-pCR (NR).

RESULTS

Proteomic and validation immunohistochemical analyses revealed that alpha-defensins (DEFA) were overexpressed in tumors from patients with a pCR. Gene expression analysis revealed that MAP2, a microtubule-associated protein, had significantly higher levels of expression in patients achieving a pCR. Elevation of MAP2 in breast cancer cell lines led to increased paclitaxel sensitivity. Furthermore, expression of genes that are associated with the basal-like, triple-negative phenotype were enriched in tumors from patients with a pCR. Analysis of a larger panel of tumors from patients receiving presurgical taxane-based treatment showed that DEFA and MAP2 expression as well as histologic features of inflammation were all statistically associated with response to therapy at the time of surgery.

CONCLUSION

We show the utility of molecular profiling of pretreatment biopsies to discover markers of response. Our results suggest the potential use of immune signaling molecules such as DEFA as well as MAP2, a microtubule-associated protein, as tumor markers that associate with response to neoadjuvant taxane-based therapy.

Differential expression of microtubule-associated protein 2 in melanocytic skin lesions

Neoplastic melanocytes may exhibit certain differentiation characteristics of other neural-crest derivatives. We aimed to study the expression of microtubule-associated protein 2 (MAP-2) in different types of melanocytic skin lesions. Paraffin-embedded sections of 42 benign nevi (BN), 22 dysplastic nevi (DN), 45 superficial spreading melanomas (SSMs), and 15 subcutaneous melanoma metastases were immunohistologically assessed using the monoclonal mouse MAP-2ab antibody (Zytomed, Berlin, Germany). The percentage MAP-2 expression of DN and SSMs was significantly increased compared with BN. Moreover, subcutaneous melanoma metastases showed significantly decreased MAP-2 expression compared with DN and SSMs. In SSMs, MAP-2 expression significantly correlated with the Breslow vertical tumor thickness, Clark level, and stage of disease. We observed that MAP-2 is differentially expressed during the development and progression of benign and malignant melanocytic skin lesions. In contrast with the findings of previous studies, our data indicate that MAP-2 is a moderately positive predictor of the progression of SSMs.

Comparison of CD23 staining patterns in Merkel cell carcinoma and non-cutaneous small cell carcinoma

BACKGROUND

During our daily practice, we observed that cluster designation 23 (CD23) (clone BU38) labels Merkel cells in normal skin. In this study, we examined the expression of CD23 in Merkel cell carcinoma (MCC) and assessed its usefulness in distinguishing MCC from non-cutaneous small cell carcinoma (SMCC).

METHODS

Immunohistochemical staining of CD23 was performed on a total of 33 MCCs, 22 SMCCs and 5 carcinoid tumors.

RESULTS

CD23 reactivity was present in 32 of 33 (97%) MCCs, 18 of 22 (82%) SMCCs and 5 of 5 (100%) carcinoid tumors. In MCC, 19 cases (59%) showed a predominance of perinuclear dot-like staining similar to cytokeratin 20, 3 (9%) showed mostly cytoplasmic staining and 10 (31%) displayed a combination of perinuclear dot-like and cytoplasmic staining. In contrast, all CD23-positive SMCCs and carcinoid tumors showed a diffuse cytoplasmic staining. There was a significant difference in the CD23 staining patterns between MCC and SMCC (p < 0.0001).

CONCLUSION

CD23 is expressed in the majority of MCC, SMCC and carcinoid tumor irrespective of clinical outcome. The distinct punctate CD23 staining for MCC may be helpful in differentiating it from SMCC. To our knowledge, this is the first study to show the expression of CD23 in neuroendocrine tumors.

Microtubule-associated proteins as targets in cancer chemotherapy

Natural and synthetic compounds that disrupt microtubule dynamics are among the most successful and widely used cancer chemotherapeutic agents. However, lack of reliable markers that predict sensitivity of cancers to these agents and development of resistance remain vexing issues. There is accumulating evidence that a family of cellular proteins that are associated with and alter the dynamics of microtubules can determine sensitivity of cancer cells to microtubule-targeting agents and play a role in tumor cell resistance to these agents. This growing family of microtubule-associated proteins (MAP) includes products of oncogenes, tumor suppressors, and apoptosis regulators, suggesting that alteration of microtubule dynamics may be one of the critical events in tumorigenesis and tumor progression. The objective of this review is to integrate the knowledge on these seemingly unrelated proteins that share a common function and examine their relevance to microtubule-targeting therapies and highlight MAPs-tubulin-drug interactions as a novel avenue for new drug discovery. Based on the available evidence, we propose that rational microtubule-targeting cancer therapeutic approaches should ideally include proteomic profiling of tumor MAPs before administration of microtubule-stabilizing/destabilizing agents preferentially in combination with agents that modulate the expression of relevant MAPs.

Merkel cell carcinoma

Background

Merkel cell carcinoma (MCC) is an unusual primary neuroendocrine carcinoma of the skin. MCC is a fatal disease, and patients have a poor chance of survival. Moreover, MCC lacks distinguishing clinical features, and thus by the time the diagnosis is made, the tumour usually have metastasized. MCC mainly affects sun-exposed areas of elderly persons. Half of the tumours are located in the head and neck region.

Methods

MCC was first described in 1972. Since then, most of the cases reported, have been in small series of patients. Most of the reports concern single cases or epidemiological studies. The present study reviews the world literature on MCC. The purpose of this article is to shed light on this unknown neuroendocrine carcinoma and provide the latest information on prognostic markers and treatment options.

Results

The epidemiological studies have revealed that large tumour size, male sex, truncal site, nodal/distant disease at presentation, and duration of disease before presentation, are poor prognostic factors. The recommended initial treatment is extensive local excision. Adjuvant radiation therapy has recently been shown to improve survival. Thus far, no chemotherapy protocol have achieved the same objective.

Conclusion

Although rare, the fatality of this malignancy makes is important to understand the etiology and pathophysiology. During the last few years, the research on MCC has produced prognostic markers, which can be translated into clinical patient care.

Microtubule-associated protein 2, a marker of neuronal differentiation, induces mitotic defects, inhibits growth of melanoma cells, and predicts metastatic potential of cutaneous melanoma

Dynamic instability of microtubules is critical for mitotic spindle assembly and disassembly during cell division, especially in rapidly dividing tumor cells. Microtubule-associated proteins (MAPs) are a family of proteins that influence this property. We showed previously that MAP2, a neuron-specific protein that stabilizes microtubules in the dendrites of postmitotic neurons, is induced in primary cutaneous melanoma but is absent in metastatic melanomas. We proposed that induction of a microtubule-stabilizing protein in primary melanoma could disrupt the dynamic instability of microtubules, inhibit cell division and prevent or delay tumor progression. Here we show, by Kaplan-Meier survival and multivariate Cox regression analysis, that patients diagnosed with MAP2+ primary melanomas have significantly better metastatic disease-free survival than those with MAP2- disease. Investigation of the mechanisms that underlie the effect of MAP2 on melanoma progression showed that MAP2 expression in metastatic melanoma cell lines leads to microtubule stabilization, cell cycle arrest in G2-M phase and growth inhibition. Disruption of microtubule dynamics by MAP2 resulted in multipolar mitotic spindles, defects in cytokinesis and accumulation of cells with large nuclei, similar to those seen in vivo in MAP2+ primary melanomas cells. These data suggest that ectopic activation of a neuronal differentiation gene in melanoma during early tumor progression inhibits cell division and correlates with inhibition or delay of metastasis.

MAP-2 expression in the human adenohypophysis and in pituitary adenomas. An immunohistochemical study

MAP-2, a well characterized member of the microtubule associated protein (MAP) family, binds to and stabilizes microtubules and is involved in cell proliferation as well as neuronal differentiation. The aim of the present work was to study MAP-2 expression in human adenohypophyses and pituitary adenomas. To our knowledge, data regarding MAP-2 expression in human pituitaries has not been reported to date. For immunohistochemistry, the streptavidin-biotin-peroxidase complex method was used. Nine non-tumorous adenohypophyses and 77 adenomas (GH-, PRL-, ACTH-, TSH-, FSH/LH- and/or alpha subunit- producing or immunonegative tumors) were investigated. The results show that MAP-2 is expressed in the cytoplasm of non-tumorous adenohypophysial cells as well as of various pituitary adenoma types. No significant correlation was found between MAP-2 expression and gender, patient age, mitotic activity, MIB-1 labelling indices, hormone immunoprofile, and endocrine status, ie. hormonal activity or lack thereof. Thus MAP-2 expression cannot be used to estimate cell proliferation rate, growth potential, endocrine activity or biologic behaviour of an adenoma. Immunopositivity appeared to be stronger in the cytoplasm of adenoma cells than in that of non-tumorous adenohypophysial cells, implying that the adenoma cells contain larger quantities of MAP-2. It can be concluded that the functional activity of MAP-2 is not associated with the manufacture of any specific adenohypophysial hormone(s) and is not limited to one specific cell type.