Classification of CEA-related positivity in primary and metastatic malignant melanoma

Aberrant Expression of Immunohistochemical Markers in Malignant Melanoma: A Review

Immunohistochemical stains are increasingly used to aid in the diagnosis of malignant melanoma, especially when the differentiation of the tumor is unclear based on examination with hematoxylin and eosin. However, aberrant expression of non-melanocytic markers has been reported in melanomas, which can sometimes be further complicated by the loss of conventional melanocytic markers. This review aims to summarize available data regarding unusual staining patterns in primary and metastatic malignant melanoma. It also raises awareness of the potential pitfalls and highlights the importance of appropriate use and interpretation of broad immunohistochemical markers in the context of clinical and histopathologic findings to facilitate the diagnosis of atypical cases of malignant melanoma.

Activation of the tumor suppressive Hippo pathway by triptonide as a new strategy to potently inhibit aggressive melanoma cell metastasis

Metastatic melanoma has a very high mortality rate despite the availability of chemotherapy, radiotherapy, and immunotherapy; therefore, more effective therapeutics are needed. The Hippo pathway plays an inhibitory role in melanoma progression, but the tumor suppressors Salvador homolog-1 (SAV1) and large tumor suppressor 1 (LATS1) in this pathway are down-regulated in melanoma. As a result, the downstream oncogenic Yes-associated protein (YAP) is active, resulting in uncontrolled melanoma growth and metastasis. Therapeutics for remedying SAV1 and LATS1 deficiency in melanoma have not yet been reported in the literature. Here, we show that the small molecule triptonide (MW 358 Da) robustly suppressed melanoma cell tumorigenicity, migration, and invasion. Furthermore, triptonide markedly reduced tumor growth and melanoma lung metastasis in tumor-bearing mice with low toxicity. Molecular mechanistic studies revealed that triptonide promoted SAV1 and LATS1 expression, strongly activated the tumor-suppressive Hippo pathway, degraded oncogenic YAP via the lysosomal pathway, and reduced levels of tumorigenic microphthalmia-associated transcription factor (MITF) in melanoma cells. Triptonide also strongly inhibited activation of AKT, a SAV1-binding signaling protein. Collectively, our results conceptually demonstrate that induction of SAV1 and LATS1 expression and activation of the tumor-suppressive Hippo pathway by triptonide potently inhibits aggressive melanoma cell growth and metastasis. These findings suggest a new strategy for developing therapeutics to treat metastatic melanoma and highlight a novel drug candidate against aggressive melanoma.

Cytokines: The Good, the Bad, and the Deadly

Over the past 30 years, the world of pharmaceutical toxicology has seen an explosion in the area of cytokines. An overview of the many aspects of cytokine safety evaluation currently in progress and evolving strategies for evaluating these important entities was presented at this symposium. Cytokines play a broad role to help the immune system respond to diseases, and drugs which modulate their effect have led to some amazing therapies. Cytokines may be "good" when stimulating the immune system to fight a foreign pathogen or attack tumors. Other "good" cytokine effects include reduction of an immune response, for example interferon β reduction of neuron inflammation in patients with multiple sclerosis. They may be "bad" when their expression causes inflammatory diseases, such as the role of tumor necrosis factor α in rheumatoid arthritis or asthma and Crohn's disease. Therapeutic modulation of cytokine expression can help the "good" cytokines to generate or quench the immune system and block the "bad" cytokines to prevent damaging inflammatory events. However, care must be exercised, as some antibody therapeutics can cause "ugly" cytokine release which can be deadly. Well-designed toxicology studies should incorporate careful assessment of cytokine modulation that will allow effective therapies to treat unmet needs. This symposium discussed lessons learned in cytokine toxicology using case studies and suggested future directions.

Bispecific antibodies for cancer therapy: the light at the end of the tunnel?

With 23 approvals in the US and other countries and four approvals outside US, antibodies are now widely recognized as therapeutic molecules. The therapeutic and commercial successes met by rituximab, trastuzumab, cetuximab and other mAbs have inspired antibody engineers to improve the efficacy of these molecules. Consequently, a new wave of antibodies with engineered Fc leading to much higher effector functions such as antibody-dependent cell-mediated cytotoxicity or complement-dependent cytotoxicity is being evaluated in the clinic, and several approvals are expected soon. In addition, research on a different class of antibody therapeutics, bispecific antibodies, has recently led to outstanding clinical results, and the first approval of the bispecific antibody catumaxomab, a T cell retargeting agent that was approved in the European Union in April 2009. This review describes the most recent advances and clinical study results in the field of bispecific antibodies, a new class of molecules that might outshine conventional mAbs as cancer immunotherapeutics in a near future.

Protein expression of carcinoembryonic antigen cell adhesion molecules in benign and malignant melanocytic skin lesions

Dysregulation of cell adhesion molecules is associated with progression of malignant melanoma. Immunohistologic study of benign nevi (BN), dysplastic nevi (DN), and primary superficial spreading melanoma (SSM) was performed for carcinoembryonic antigen (CEA) and CEA cell adhesion molecule-1 (CEACAM1) using monoclonal antibodies. We investigated BN (n = 42), DN (n = 22), thin SSM (n = 21), and thick SSM (n = 21). CEA expression in melanomas and DN was significantly increased compared with BN. CEA expression in thick SSM was significantly higher than in DN. Compared with BN, expression of CEACAM1 in melanomas was significantly increased. CEACAM1 expression in thick SSM was significantly increased compared with DN and thin SSM. Our data support the findings of previous studies indicating that cell adhesion molecules of the CEA family may have a role in the development and progression of cutaneous melanoma and potentially serve as prognostic markers.

C-type lectins on dendritic cells: key modulators for the induction of immune responses

DCs (dendritic cells) are specialized in the recognition of pathogens and play a pivotal role in the control of immune responses. DCs are also important for homoeostatic control, recognizing self-antigens and tolerizing the tissue environment. The nature of the antigen recognized tilts the balance towards immunity or tolerance. CLRs (C-type lectin receptors) expressed by DC are involved in the recognition and capture of many glycosylated self-antigens and pathogens. It is now becoming clear that these CLRs may not only serve as antigen receptors allowing internalization and antigen presentation, but also function in the recognition of glycosylated self-antigens, and as adhesion and/or signalling molecules. The expression of C-type lectins is very sensitive to maturation stimuli, leading to down-regulation as DCs mature. CLRs such as DC-SIGN (DC-specific intracellular adhesion molecule-3 grabbing non-integrin) recognizes high-mannose-containing structures and Lewis antigens (Le(x), Le(y), Le(b) and Le(a)), whereas the CLR MGL (macrophage galactose/N-acetylgalactosamine-specific C-type lectin) recognizes GalNAc. Le(x), Le(y) and GalNAc glycan structures are often expressed on tumours. We have demonstrated that glycan modification of antigen can strongly enhance MHC class I responses and the induction of antigen-specific cytotoxic T-lymphocytes, indicating that glycosylated antigen targets C-type lectin to enhance antigen-specific T-cell responses. Moreover, these CLRs induce signalling processes in DCs and specific cytokine responses in combination with TLR (Toll-like receptor) triggering. This implies that specific C-type lectin-targeted antigens can regulate T-cell polarization. Understanding the diversity of C-type lectins being expressed on DCs as well as their carbohydrate-specific recognition profiles should promote understanding of pathogen recognition in many diseases, as well as the regulation of cellular interactions of DCs that are essential in the control of immunity.

Cytoplasmic beta-catenin is lacking in a subset of melanoma-associated naevi, but is detectable in naevus-associated melanomas: potential implications for melanoma tumorigenesis?

BACKGROUND

An excess of intracellular beta-catenin protein is triggered by various genetic alterations in melanoma cell lines, and has been suggested to play a role in melanoma tumorigenesis.

OBJECTIVES

To investigate the role played in vivo by beta-catenin in melanoma tumorigenesis, we compared the cytoplasmic detection of beta-catenin in benign melanocytic cells vs. malignant melanoma cells presumably generated from these benign melanocytic cells. For this purpose, melanocytic naevi occurring in association with melanoma, which were suggested to be melanoma precursors, were compared with their associated melanoma for beta-catenin cytoplasmic immunoreactivity.

METHODS

Fifty-seven consecutive cases of primary cutaneous melanoma were considered, and 15 of them were found to be associated with a melanocytic naevus portion. The naevus portion showed features of acquired melanocytic naevus (total 12 cases: five dysplastic, seven intradermal) or congenital growth pattern naevus (total three cases: one superficial, two deep). All specimens were immunohistochemically investigated for beta-catenin.

RESULTS

Virtually all primary cutaneous melanomas, including those associated with a naevus portion, showed cytoplasmic beta-catenin positivity. However, the intradermal naevus portion was consistently cytoplasmic beta-catenin negative, while both the dysplastic and the congenital naevus portions were cytoplasmic beta-catenin positive.

CONCLUSIONS

Beta-catenin excess may play a role in melanoma tumorigenesis, because beta-catenin cytoplasmic reactivity was found in primary cutaneous melanoma but not in its associated intradermal naevus precursor. As, however, beta-catenin cytoplasmic reactivity was detected not only in primary cutaneous melanoma but also in its associated dysplastic/congenital naevus precursors, beta-catenin stabilization alone is not sufficient to play a decisive role for melanoma onset.

A panel immunoblot using co-incubated monoclonal antibodies for identification of melanoma cells

Antigen expression in melanoma is heterogeneous. Immunophenotyping using a panel of monoclonal antibodies may facilitate immunotherapy. An immunoblot procedure was developed to detect antigens in melanoma cells. Numerous monoclonal antibodies were tested to determine if (1) antigens were detected after transfer to membranes, (2) single bands or discrete multiple bands were obtained, (3) co-incubation of multiple monoclonal antibodies had no interference, and (4) banding patterns were non-overlapping. Antigens were selected based upon their association with melanoma and the availability of respective monoclonal antibodies. Antigens were melanoma antigen recognized by T-cells (MART-1), tyrosinase, tyrosinase-related protein 1 (TRP-1), S100, vimentin, glycoprotein 130 (gp130), a carcinoembryonic antigen (CEA)-like marker, KBA-62 and NKI-C3. Actin positive controls could be assessed simultaneously. Test samples were separated by polyacrylamide gel electrophoresis in a 4-15% polyacrylamide gradient, transferred to polyvinylidine fluoride membrane, blotted using a Fast-Blot apparatus (Pierce), and developed using diaminobenzidine/metal. Melanoma cell lines were immunophenotyped using this panel immunoblot, and were compared to a standard control and to non-melanoma cells. Up to four antigens could be detected simultaneously in a single lane of the immunoblot, using a single test sample of greater than 100000 cells.

Morphological and immunophenotypic variations in malignant melanoma

A variety of cytomorphological features, architectural patterns and stromal changes may be observed in malignant melanomas. Hence, melanomas may mimic carcinomas, sarcomas, benign stromal tumours, lymphomas, plasmacytomas and germ cell tumours. Melanomas may be composed of large pleomorphic cells, small cells, spindle cells and may contain clear, signet-ring, pseudolipoblastic, rhabdoid, plasmacytoid or balloon cells. Various inclusions and phagocytosed material may be present in their cytoplasm. Nuclei may show bi- or multi-nucleation, lobation, inclusions, grooving and angulation. Architectural variations include fasciculation, whorling, nesting, trabeculation, pseudoglandular/pseudopapillary/pseudofollicular, pseudorosetting and angiocentric patterns. Myxoid or desmoplastic changes and very rarely pseudoangiosarcomatous change, granulomatous inflammation or osteoclastic giant cell response may be seen in the stroma. The stromal blood vessels may exhibit a haemangiopericytomatous pattern, proliferation of glomeruloid blood vessels and perivascular hyalinization. Occasionally, differentiation to nonmelanocytic structures (Schwannian, fibro-/myofibroblastic, osteocartilaginous, smooth muscle, rhabdomyoblastic, ganglionic and ganglioneuroblastic) may be observed. Typically melanomas are S100 protein, NKIC3, HMB-45, Melan-A and tyrosinase positive but some melanomas may exhibit an aberrant immunophenotype and may express cytokeratins, desmin, smooth muscle actin, KP1 (CD68), CEA, EMA and VS38. Very rarely, neurofilament protein and GFAP positivity may be seen.

Lewis blood group and CEA related antigens; coexpressed cell-cell adhesion molecules with roles in the biological progression and dissemination of tumours

The Lewis blood group and carcinoembryonic antigen (CEA) related antigens have adhesive functions in human tissues, with roles in embryonic sorting and migration of cells (organogenesis), differentiation and protection of normal mucosal tissues, migration of neutrophils, bacterial binding, and tumour differentiation and dissemination. In the key areas of mucosal protection, neutrophil binding, and tumour metastasis, they are often coexpressed on the outer cell membrane, with Lewis blood group antigens forming the terminal carbohydrate chains on a CEA related glycoprotein backbone. The central role of these antigens in the mechanism of neutrophil binding to endothelium in inflammation highlights a fascinating paradigm for tumour cell dissemination and metastasis, and expression is linked to disease prognosis. This review outlines the structure, function, and comparative roles of these antigens in human tissues.

Alterations in cadherin and catenin expression during the biological progression of melanocytic tumours

AIMS

Compelling evidence from cell culture studies implicates cadherins in the neoplastic progression of melanocytic tumours but few reports describe the expression of cadherins and the related transmembrane proteins, catenins, in a full range of benign and malignant excised melanocytic tumours.

METHODS

Using immunohistochemistry and western blotting after tissue fractionation, the pattern of expression of cadherins/catenins was studied in a range of surgically excised melanocytic tumours, from dysplastic naevi to stage III cutaneous metastatic malignant melanoma.

RESULTS

Appropriate membranous expression of E-cadherins and P-cadherins is seen in dysplastic naevocytes with an epithelioid phenotype and is largely maintained with malignant transformation to radial growth phase melanoma and primary vertical growth phase malignant melanoma. Loss of membranous E-cadherin is seen in a small number of vertical growth phase melanomas only when metastasis has occurred. However, there is a concomitant dramatic loss of membranous P-cadherin expression in all melanomas at the same stage. A minority of metastatic melanomas show de novo membranous N-cadherin expression in comparison with dysplastic naevi and primary melanoma. Membranous expression of the desmosomal cadherin, desmoglein, was not seen in any tumour studied. Frequently, beta catenin is aberrantly produced in the cytoplasm of cells in dysplastic naevi and metastatic malignant melanoma, with an implied compromise to adhesive function. Furthermore, membranous gamma catenin expression was not seen in any of the 70 melanocytic tumours studied, implying obligatory transmembrane binding of cadherins to beta catenin for maintenance of adhesive function.

CONCLUSIONS

The most important alterations in membranous cadherin and catenin expression are seen late in the biological progression of melanocytic tumours at the stage of "in transit" or regional lymph node metastasis, with implications for tumour growth, invasion, and dissemination.

Neoplasms with sweat gland differentiation express various glycoproteins of the carcinoembryonic antigen (CEA) family

Carcinoembryonic antigen (CEA) is a well-established marker for sweat gland differentiation in adnexal neoplasms. In contrast to previous assumptions, CEA does not represent a single oncofetal antigen but comprises a family of homologous glycoproteins, i.e. the classical CEA-180, biliary glycoprotein (BGP), and non-specific crossreacting antigens (NCA). The aim of the study was to evaluate the distribution of the respective glycoproteins of the CEA family in sweat gland neoplasms, as compared to normal sweat glands. A panel of mono-specific antibodies was applied to a total of 83 samples of hyperplastic and cystic alterations of sweat glands, sweat gland neoplasms, and cutaneous metastases of different origin. Within a single group of neoplasms the immunohistochemical profile was rather consistent. Staining for both CEA-180 and NCA-90 indicated ductal differentiation of both eccrine and apocrine glands. Co-expression of CEA-180, NCA-90, and BGP was consistent with differentiation towards the secretory part of eccrine glands or the transitional portion of proximal ducts. Neoplasms with signs of apocrine secretion showed a preferential immunoreactivity for NCA-90 and BGP. In conclusion, a specification of the members of the CEA family may be of some value in the differential diagnosis of adnexal neoplasms, but not in the discrimination of sweat gland carcinoma from metastatic carcinoma.