E- to N-cadherin switch in melanoma is associated with decreased expression of phosphatase and tensin homolog and cancer progression

Differentiation States of Phenotypic Transition of Melanoma Cells Are Revealed by 3D Cell Cultures

Melanoma is characterized by high metastatic potential favored by the epithelial-to-mesenchymal transition (EMT), leading melanoma cells to exhibit a spectrum of typical EMT markers. This study aimed to analyze the expression of EMT markers in A375 and BLM melanoma cell lines cultured in 2D monolayers and 3D spheroids using morphological and molecular methods. The expression of EMT markers was strongly affected by 3D arrangement and revealed a hybrid phenotype for the two cell lines. Indeed, although E-cadherin was almost undetectable in both A375 and BLM cells, cortical actin was detected in A375 2D monolayers and 3D spheroids and was strongly expressed in BLM 3D spheroids. The mesenchymal marker N-cadherin was significantly up-regulated in A375 3D spheroids while undetectable in BLM cells, but vimentin was similarly expressed in both cell lines at the gene and protein levels. This pattern suggests that A375 cells exhibit a more undifferentiated/mesenchymal phenotype, while BLM cells have more melanocytic/differentiated characteristics. Accordingly, the Zeb1 and 2, Slug, Snail and Twist gene expression analyses showed that they were differentially expressed in 2D monolayers compared to 3D spheroids, supporting this view. Furthermore, A375 cells are characterized by a greater invasive potential, strongly influenced by 3D arrangement, compared to the BLM cell line, as evaluated by SDS-zymography and TIMPs gene expression analysis. Finally, TGF-β1, a master controller of EMT, and lysyl oxidase (LOX), involved in melanoma progression, were strongly up-regulated by 3D arrangement in the metastatic BLM cells alone, likely playing a role in the metastatic phases of melanoma progression. Overall, these findings suggest that A375 and BLM cells possess a hybrid/intermediate phenotype in relation to the expression of EMT markers. The former is characterized by a more mesenchymal/undifferentiated phenotype, while the latter shows a more melanocytic/differentiated phenotype. Our results contribute to the characterization of the role of EMT in melanoma cells and confirm that a 3D cell culture model could provide deeper insight into our understanding of the biology of melanoma.

A mechanism of melanogenesis mediated by E-cadherin downregulation and its involvement in solar lentigines

OBJECTIVE

Intensive studies have revealed that pleiotropic melanocytic factors are associated with age-spot formation. Dysfunctional keratinocyte differentiation is thought to be an upstream cause of age-spot formation. Although it has been shown that keratinocyte differentiation is mediated by the cell-cell contact factor E-cadherin, its involvement in age-spot formation remains unknown. Thus, to determine the origin of age-spots and an integrated solution for the same, we focused on E-cadherin expression in the present study.

METHODS

First, we assessed the solar lentigines in cutaneous and cultured cells by means of immunofluorescence staining. Following that, keratinocytes treated with siRNAs against E-cadherin were co-cultured with melanocytes, and the secreted factors were identified by means of proteomic analysis of the culture supernatants. We also performed quantitative PCR to assess melanogenesis activity and screen ingredients. For behavioural analysis of melanocytes, we performed time-lapse imaging using confocal laser scanning microscopy.

RESULTS

E-cadherin expression was downregulated in the epidermis of the solar lentigines, suggesting its involvement in age-spot formation. E-cadherin knocked down keratinocytes not only promoted the secretion of melanocytic/inflammatory factors but also increased melanogenesis by upregulating the expression of melanogenesis factors. Furthermore, live-imaging showed that the downregulation of E-cadherin inhibited melanocyte dynamics and accelerated melanin uptake. Finally, we identified Rosa multiflora fruit extract as a solution that can upregulate E-cadherin expression in keratinocytes.

CONCLUSION

Our findings showed that E-cadherin downregulation triggers various downstream melanocytic processes, such as the secretion of melanocytic factors and melanogenesis. Additionally, we showed that the Rosa multiflora fruit extract upregulated E-cadherin expression in keratinocytes.

Retinoblastoma-Binding Protein 5 Regulates H3K4 Methylation Modification to Inhibit the Proliferation of Melanoma Cells by Inactivating the Wnt/β-Catenin and Epithelial-Mesenchymal Transition Pathways

Histone 3 lysine 4 methylation (H3K4me), especially histone 3 lysine 4 trimethylation (H3K4me3), is one of the most extensively studied patterns of histone modification and plays crucial roles in many biological processes. However, as a part of H3K4 methyltransferase that participates in H3K4 methylation and transcriptional regulation, retinoblastoma-binding protein 5 (RBBP5) has not been well studied in melanoma. The present study sought to explore RBBP5-mediated H3K4 histone modification and the potential mechanisms in melanoma. RBBP5 expression in melanoma and nevi specimens was detected by immunohistochemistry. Western blotting was performed for three pairs of melanoma cancer tissues and nevi tissues. In vitro and in vivo assays were used to investigate the function of RBBP5. The molecular mechanism was determined using RT-qPCR, western blotting, ChIP assays, and Co-IP assays. Our study showed that RBBP5 was significantly downregulated in melanoma tissue and cells compared with nevi tissues and normal epithelia cells (P < 0.05). Reducing RBBP5 in human melanoma cells leads to H3K4me3 downregulation and promotes cell proliferation, migration, and invasion. On the one hand, we verified that WSB2 was an upstream gene of RBBP5-mediated H3K4 modification, which could directly bind to RBBP5 and negatively regulate its expression. On the other hand, we also confirmed that p16 (a cancer suppressor gene) was a downstream target of H3K4me3, the promoter of which can directly bind to H3K4me3. Mechanistically, our data revealed that RBBP5 inactivated the Wnt/β-catenin and epithelial-mesenchymal transition (EMT) pathways (P < 0.05), leading to melanoma suppression. Histone methylation is rising as an important factor affecting tumorigenicity and tumor progression. Our findings verified the significance of RBBP5-mediated H3K4 modification in melanoma and the potential regulatory mechanisms of melanoma proliferation and growth, suggesting that RBBP5 is a potential therapeutic target for the treatment of melanoma.

Comprehensive analysis of prognostic significance of cadherin (CDH) gene family in breast cancer

Breast cancer is one of the leading deaths in all kinds of malignancies; therefore, it is important for early detection. At the primary tumor site, tumor cells could take on mesenchymal properties, termed the epithelial-to-mesenchymal transition (EMT). This process is partly regulated by members of the cadherin (CDH) family of genes, and it is an essential step in the formation of metastases. There has been a lot of study of the roles of some of the CDH family genes in cancer; however, a holistic approach examining the roles of distinct CDH family genes in the development of breast cancer remains largely unexplored. In the present study, we used a bioinformatics approach to examine expression profiles of CDH family genes using the Oncomine, Gene Expression Profiling Interactive Analysis 2 (GEPIA2), cBioPortal, MetaCore, and Tumor IMmune Estimation Resource (TIMER) platforms. We revealed that CDH1/2/4/11/12/13 messenger (m)RNA levels are overexpressed in breast cancer cells compared to normal cells and were correlated with poor prognoses in breast cancer patients’ distant metastasis-free survival. An enrichment analysis showed that high expressions of CDH1/2/4/11/12/13 were significantly correlated with cell adhesion, the extracellular matrix remodeling process, the EMT, WNT/beta-catenin, and interleukin-mediated immune responses. Collectively, CDH1/2/4/11/12/13 are thought to be potential biomarkers for breast cancer progression and metastasis.

Ulcerated Cutaneous Melanoma: A Review of the Clinical, Histologic, and Molecular Features Associated with a Clinically Aggressive Histologic Phenotype

The presence of ulceration in melanoma is associated with poor clinical outcomes and is the third most powerful predictor of survival in the AJCC Melanoma Staging System after tumor thickness and mitotic activity. The aggressive biological behavior associated with ulceration has been hypothesized to be the result of an intrinsic biological attribute that favors dissemination and presents locally with the loss of epidermal integrity. Among the features of ulcerated melanoma, many show promise as potential prognostic tools, markers of differential immunogenicity and indicators of oncogenic drivers of invasion and metastasis. The incidence of ulcerated melanoma is greater in males, increases with age and with systemic inflammatory risk factors (diabetes, smoking, low vitamin D, elevated body mass index). Patients with ulcerated primary tumors seem to exclusively benefit from adjuvant interferon (IFN) therapy, which is likely the consequence of an altered tumor microenvironment. When ulceration is present, there is a higher density of macrophages and dendritic cells and enhanced expression of pro-inflammatory cytokines, such as IL-6. There is also an increased expression of proteins involved in tumor antigen presentation in ulcerated melanomas. Histologically, vascular density, vasculogenic mimicry and angiotropism are all significantly correlated with ulceration in melanoma. The presence of ulceration is associated with reduced protein expression of E-cadherin and PTEN and elevated levels of N-cadherin and the matrix metalloproteinases. Differential microRNA expression also holds promise as a potential prognostic biomarker of malignancy and disease spread within the setting of ulceration. However, the molecular and cellular differences associated with the ulcerated state are complex and further study will aid in determining how these differences can be harnessed to improve care for patients with melanoma.

Therapeutic Potential of Nitric Oxide‒Releasing Selective Estrogen Receptor Modulators in Malignant Melanoma

Malignant melanoma has a steadily increasing incidence, but treatment options are still limited, and the prognosis for patients, especially for men, is poor. To investigate whether targeting estrogen receptor (ER) signaling is a valid therapeutic approach, we retrospectively analyzed ER gene expression profiles in 448 patients with melanoma. High ERα gene (ESR1) expression was associated with improved overall survival (hazard ratio = 0.881; 95% confidence interval = 0.793-0.979; P = 0.018) and increased with tumor stage, whereas ERβ gene (ESR2) expression did not change with tumor progression. This seemingly protective function of ERα led us to speculate that specific targeting of ERβ has a therapeutic benefit in malignant melanoma. An ERβ-selective ER modulator with nitric oxide‒releasing moiety (nitric oxide‒releasing selective ER modulator 4d [NO-SERM 4d]) significantly reduced the prometastatic behavior of two melanoma cell lines (A2058 and MEL-JUSO). Epithelial‒mesenchymal transition in melanoma is consistent with a switch from E- to N-cadherin expression, mediating the invasive phenotype. NO-SERM 4d reduced N-cadherin expression and impaired spheroid formation in A2058 cells. In addition, the growth of A2058 spheroids was significantly reduced, confirming the antitumorigenic potential of NO-SERM 4d. Targeting ERβ signaling combined with targeted nitric oxide release represents a promising therapeutic approach in malignant melanoma that has the potential to prevent metastatic spread and reduce tumor growth.

Epithelial to mesenchymal transition during mammalian neural crest cell delamination

Epithelial to mesenchymal transition (EMT) is a well-defined cellular process that was discovered in chicken embryos and described as "epithelial to mesenchymal transformation" [1]. During EMT, epithelial cells lose their epithelial features and acquire mesenchymal character with migratory potential. EMT has subsequently been shown to be essential for both developmental and pathological processes including embryo morphogenesis, wound healing, tissue fibrosis and cancer [2]. During the past 5 years, interest and study of EMT especially in cancer biology have increased exponentially due to the implied role of EMT in multiple aspects of malignancy such as cell invasion, survival, stemness, metastasis, therapeutic resistance and tumor heterogeneity [3]. Since the process of EMT in embryogenesis and cancer progression shares similar phenotypic changes, core transcription factors and molecular mechanisms, it has been proposed that the initiation and development of carcinoma could be attributed to abnormal activation of EMT factors usually required for normal embryo development. Therefore, developmental EMT mechanisms, whose timing, location, and tissue origin are strictly regulated, could prove useful for uncovering new insights into the phenotypic changes and corresponding gene regulatory control of EMT under pathological conditions. In this review, we initially provide an overview of the phenotypic and molecular mechanisms involved in EMT and discuss the newly emerging concept of epithelial to mesenchymal plasticity (EMP). Then we focus on our current knowledge of a classic developmental EMT event, neural crest cell (NCC) delamination, highlighting key differences in our understanding of NCC EMT between mammalian and non-mammalian species. Lastly, we highlight available tools and future directions to advance our understanding of mammalian NCC EMT.

Signal pathways of melanoma and targeted therapy

Melanoma is the most lethal skin cancer that originates from the malignant transformation of melanocytes. Although melanoma has long been regarded as a cancerous malignancy with few therapeutic options, increased biological understanding and unprecedented innovations in therapies targeting mutated driver genes and immune checkpoints have substantially improved the prognosis of patients. However, the low response rate and inevitable occurrence of resistance to currently available targeted therapies have posed the obstacle in the path of melanoma management to obtain further amelioration. Therefore, it is necessary to understand the mechanisms underlying melanoma pathogenesis more comprehensively, which might lead to more substantial progress in therapeutic approaches and expand clinical options for melanoma therapy. In this review, we firstly make a brief introduction to melanoma epidemiology, clinical subtypes, risk factors, and current therapies. Then, the signal pathways orchestrating melanoma pathogenesis, including genetic mutations, key transcriptional regulators, epigenetic dysregulations, metabolic reprogramming, crucial metastasis-related signals, tumor-promoting inflammatory pathways, and pro-angiogenic factors, have been systemically reviewed and discussed. Subsequently, we outline current progresses in therapies targeting mutated driver genes and immune checkpoints, as well as the mechanisms underlying the treatment resistance. Finally, the prospects and challenges in the development of melanoma therapy, especially immunotherapy and related ongoing clinical trials, are summarized and discussed.

Increased expression of secreted protein acidic and rich in cysteine and tissue inhibitor of metalloproteinase-3 in epidermotropic melanoma metastasis

Primary cutaneous melanoma generally arises in the epidermis, followed by invasion into the dermis. Although infrequent, invasive melanoma cells can, alternatively, migrate to the intraepidermal area and form epidermotropic melanoma metastasis (EMM). In this study, we focused on this unique manner of metastasis. To identify the key molecules which affect EMM, gene expression in EMM was compared with that in common skin metastasis (CSM). Polymerase chain reaction (PCR) analysis was performed for genes affecting the extracellular matrix, cellular adhesion, and tumor metastasis on three EMM and three CSM samples as an initial screening. For molecules showing altered expression in the EMM, expression levels were further verified using real-time quantitative PCR (qPCR) and immunohistochemistry. Five molecules showed an expression difference in the initial screening. Among these, secreted protein acidic and rich in cysteine (SPARC) was preferentially expressed in EMM (p = 0.01) by real-time qPCR. Another candidate molecule, tissue inhibitor of metalloproteinase-3 (TIMP3), was not statistically significant (p = 0.07), but showed the tendency of higher expression. These results correlated negatively to expression of N-cadherin and β-catenin. The upregulation of SPARC and TIMP3 may disrupt the continuity of the canonical Wnt pathway. This pathway regulates adhesion activity of melanoma cells to localize within the dermis, which consequently promotes EMM. Our study highlights the potential role of SPARC and TIMP3 as key molecules in EMM, and analysis of EMM may contribute for understanding melanoma invasion between the epidermis and the dermis.

Aetiology and Pathogenesis of Cutaneous Melanoma: Current Concepts and Advances

Melanoma develops from malignant transformations of the pigment-producing melanocytes. If located in the basal layer of the skin epidermis, melanoma is referred to as cutaneous, which is more frequent. However, as melanocytes are be found in the eyes, ears, gastrointestinal tract, genitalia, urinary system, and meninges, cases of mucosal melanoma or other types (e.g., ocular) may occur. The incidence and morbidity of cutaneous melanoma (cM) are constantly increasing worldwide. Australia and New Zealand are world leaders in this regard with a morbidity rate of 54/100,000 and a mortality rate of 5.6/100,000 for 2015. The aim of this review is to consolidate and present the data related to the aetiology and pathogenesis of cutaneous melanoma, thus rendering them easier to understand. In this article we will discuss these problems and the possible impacts on treatment for this disease.

Decoding Melanoma Development and Progression: Identification of Therapeutic Vulnerabilities

Melanoma, a cancer of the skin, arises from transformed melanocytes. Melanoma has the highest mutational burden of any cancer partially attributed to UV induced DNA damage. Localized melanoma is “curable” by surgical resection and is followed by radiation therapy to eliminate any remaining cancer cells. Targeted therapies against components of the MAPK signaling cascade and immunotherapies which block immune checkpoints have shown remarkable clinical responses, however with the onset of resistance in most patients, and, disease relapse, these patients eventually become refractory to treatments. Although great advances have been made in our understanding of the metastatic process in cancers including melanoma, therapy failure suggests that much remains to be learned and understood about the multi-step process of tumor metastasis. In this review we provide an overview of melanocytic transformation into malignant melanoma and key molecular events that occur during this evolution. A better understanding of the complex processes entailing cancer cell dissemination will improve the mechanistic driven design of therapies that target specific steps involved in cancer metastasis to improve clinical response rates and overall survival in all cancer patients.

Cell Adhesion Molecules in Plasticity and Metastasis

Prior to metastasis, modern therapeutics and surgical intervention can provide a favorable long-term survival for patients diagnosed with many types of cancers. However, prognosis is poor for patients with metastasized disease. Melanoma is the deadliest form of skin cancer, yet in situ and localized, thin melanomas can be biopsied with little to no postsurgical follow-up. However, patients with metastatic melanoma require significant clinical involvement and have a 5-year survival of only 34% to 52%, largely dependent on the site of colonization. Melanoma metastasis is a multi-step process requiring dynamic changes in cell surface proteins regulating adhesiveness to the extracellular matrix (ECM), stroma, and other cancer cells in varied tumor microenvironments. Here we will highlight recent literature to underscore how cell adhesion molecules (CAM) contribute to melanoma disease progression and metastasis.

E-Cadherin Expression in Canine Melanocytic Tumors: Histological, Immunohistochemical, and Survival Analysis

E-cadherin, a glycoprotein involved in cell-cell adhesion, has a pivotal role in epithelial-mesenchymal transition, a process through which neoplastic epithelial cells develop an invasive phenotype. In human cutaneous melanomas, decreased E-cadherin expression is associated with shorter survival and increased Breslow thickness, whereas in the dog its role is poorly understood. Tumor thickness and modified Clark level were recently proposed as useful features to assess canine melanocytic tumors, but no studies investigated their association with E-cadherin expression. We performed immunohistochemistry on 77 formalin-fixed, paraffin-embedded primary canine melanocytic tumors. A 3-tier and a 2-tier classification system for assessing E-cadherin expression were tested, with the latter being more informative for the assessment of canine melanocytic tumors. E-cadherin expression was lower in cutaneous melanomas than melanocytomas, as well as in amelanotic tumors compared to pigmented tumors. In amelanotic melanomas, absent E-cadherin expression was associated with an unfavorable outcome, suggesting a potential use of this marker in defining the prognosis of amelanotic melanomas. E-cadherin expression was lower in tumors with greater tumor thickness and modified Clark level ≥IV, suggesting its possible utility in identifying the most invasive tumors. The expression of E-cadherin in oral melanomas was heterogeneous, but was associated with pigmentation and clinical outcome; thus, E-cadherin evaluation could be advantageous to detect the most aggressive neoplasms. However, cutaneous melanomas without E-cadherin expression frequently had a favorable clinical outcome. Hence, its importance as prognostic factor should be carefully considered depending on the tumor origin.

An Algorithmic Immunohistochemical Approach to Define Tumor Type and Assign Site of Origin

Immunohistochemistry represents an indispensable complement to an epidemiology and morphology-driven approach to tumor diagnosis and site of origin assignment. This review reflects the state of my current practice, based on 15-years' experience in Pathology and a deep-dive into the literature, always striving to be better equipped to answer the age old questions, "What is it, and where is it from?" The tables and figures in this manuscript are the ones I "pull up on the computer" when I am teaching at the microscope and turn to myself when I am (frequently) stuck. This field is so exciting because I firmly believe that, through the application of next-generation immunohistochemistry, we can provide better answers than ever before. Specific topics covered in this review include (1) broad tumor classification and associated screening markers; (2) the role of cancer epidemiology in determining pretest probability; (3) broad-spectrum epithelial markers; (4) noncanonical expression of broad tumor class screening markers; (5) a morphologic pattern-based approach to poorly to undifferentiated malignant neoplasms; (6) a morphologic and immunohistochemical approach to define 4 main carcinoma types; (7) CK7/CK20 coordinate expression; (8) added value of semiquantitative immunohistochemical stain assessment; algorithmic immunohistochemical approaches to (9) "garden variety" adenocarcinomas presenting in the liver, (10) large polygonal cell adenocarcinomas, (11) the distinction of primary surface ovarian epithelial tumors with mucinous features from metastasis, (12) tumors presenting at alternative anatomic sites, (13) squamous cell carcinoma versus urothelial carcinoma, and neuroendocrine neoplasms, including (14) the distinction of pheochromocytoma/paraganglioma from well-differentiated neuroendocrine tumor, site of origin assignment in (15) well-differentiated neuroendocrine tumor and (16) poorly differentiated neuroendocrine carcinoma, and (17) the distinction of well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma; it concludes with (18) a discussion of diagnostic considerations in the broad-spectrum keratin/CD45/S-100-"triple-negative" neoplasm.

Precise Immunodetection of PTEN Protein in Human Neoplasia

PTEN is a major tumor-suppressor protein whose expression and biological activity are frequently diminished in sporadic or inherited cancers. PTEN gene deletion or loss-of-function mutations favor tumor cell growth and are commonly found in clinical practice. In addition, diminished PTEN protein expression is also frequently observed in tumor samples from cancer patients in the absence of PTEN gene alterations. This makes PTEN protein levels a potential biomarker parameter in clinical oncology, which can guide therapeutic decisions. The specific detection of PTEN protein can be achieved by using highly defined anti-PTEN monoclonal antibodies (mAbs), characterized with precision in terms of sensitivity for the detection technique, specificity for PTEN binding, and constraints of epitope recognition. This is especially relevant taking into consideration that PTEN is highly targeted by mutations and posttranslational modifications, and different PTEN protein isoforms exist. The precise characterization of anti-PTEN mAb reactivity is an important step in the validation of these reagents as diagnostic and prognostic tools in clinical oncology, including their routine use in analytical immunohistochemistry (IHC). Here, we review the current status on the use of well-defined anti-PTEN mAbs for PTEN immunodetection in the clinical context and discuss their potential usefulness and limitations for a more precise cancer diagnosis and patient benefit.

FOXC2 expression and epithelial-mesenchymal phenotypes are associated with castration resistance, metastasis and survival in prostate cancer

Epithelial–mesenchymal transition (EMT) is important for tumour cell invasion and metastasis and is a feature of aggressive carcinomas. EMT is characterised by reduced E‐cadherin and increased N‐cadherin expression (EN‐switch), and increased expression of the EMT‐regulating transcription factor Forkhead box protein C2 (FOXC2) has been associated with progression and poor prognosis in various malignancies. FOXC2 was recently highlighted as a novel therapy target in prostate cancer, but survival data on FOXC2 are lacking. This study evaluates the expression of FOXC2, E‐cadherin and N‐cadherin in different prostatic tissues focusing on EMT, clinico‐pathological phenotype, recurrence and patient survival. Tissue microarray sections from 338 radical prostatectomies (1986–2007) with long and complete follow‐up, 33 castration resistant prostate cancers, 33 non‐skeletal metastases, 13 skeletal metastases and 41 prostatic hyperplasias were stained immunohistochemically for FOXC2, E‐cadherin and N‐cadherin. FOXC2 was strongly expressed in primary carcinomas, including castration resistant tumours and metastatic lesions as compared to benign prostatic hyperplasia. A hybrid epithelial–mesenchymal phenotype, with co‐expression of E‐cadherin and N‐cadherin, was found in the majority of skeletal metastases and in a substantial proportion of castration resistant tumours. In localised carcinomas, the EN‐switch was associated with adverse clinico‐pathological variables, such as extra‐prostatic extension, high pathological stage and lymph node infiltration. In univariate survival analyses of the clinically important, large subgroup of 199 patients with Gleason score 7, high FOXC2 expression and EN‐switching were significantly associated with shorter time to clinical recurrence, skeletal metastases and cancer specific death. In multivariate Cox' survival analysis, high FOXC2 and the EN‐switch, together with Gleason grade group (GG3 versus GG2), were independent predictors of time to these end‐points. High FOXC2 gene expression (mRNA) was also related to patient outcome, validating our immunohistochemical findings. FOXC2 and factors signifying EMT or its intermediate states may prove important as biomarkers for aggressive disease and are potential novel therapy targets in prostate cancer.

Invasiveness-triggered state transition in malignant melanoma cells

Cancer cells are considered to have high morphological heterogeneity in human melanoma tissue. Here, we report that epithelial cancer cells are dominant in different development stages of human melanoma tissues. The cellular and molecular mechanisms that maintain melanoma cells in the epithelial state are further investigated in the A2058 cell line. We find that micropore (8 µm) transwell invasion, but not superficial migration in the scratch assay, can induce remarkable morphological changes between epithelial and mesenchymal melanoma cells within 4 days. The morphological switch is associated with dynamic changes of epithelial-mesenchymal transition (EMT) hallmarks E-cadherin and vimentin. Further immunoflurencent staining and co-immunoprecipitation assay showed the uncoupling of the M3 muscarinic acetylcholine receptor (mAChR) and the p75 neurotrophin receptor (p75NTR) in epithelial melanoma cells. Specific knockdown of M3 mAChR by small interfering RNA (siRNA) significantly abrogates the transition of spindle-shaped mesenchymal cells to epithelial cells. Collectively, we report a cellular model of invasiveness-triggered state transition (ITST) in which melanoma cell invasion can induce morphological changes between epithelial and mesenchymal cells. ITST is one of the biological basis for maintaining metastatic melanoma cells in the epithelial state. Furthermore, M3 mAChR receptor-mediated ITST provides a novel therapeutic strategy to inhibit the development of malignant melanoma.

Morphological Plasticity of Human Melanoma Cells Is Determined by Nanoscopic Patterns of E- and N-Cadherin Interactions

Loss of E-cadherin and concomitant upregulation of N-cadherin is known as the cadherin switch, and has been implicated in melanoma progression. Mechanistically, homophilic ligation of N-cadherin-expressing melanoma cells with N-cadherin presented within the microenvironment is thought to facilitate invasion. However, the biophysical aspects governing molecular specificity and function of such interactions remain unclear. By using precisely defined nano-patterns of N- or E-cadherin (with densities tunable by more than one order of magnitude from 78 to 1,128 ligands/μm²), we analyzed adhesion and spreading of six different human melanoma cell lines with distinct constitutive cadherin expression patterns. Cadherin-mediated homophilic cell interactions (N/N and E/E) with cadherin-functionalized nano-matrices revealed an unexpected functional dichotomy inasmuch as melanoma cell adhesion was cadherin density-dependent, while spreading and lamellipodia formation were independent of cadherin density. Surprisingly, E-cadherin-expressing melanoma cells also interacted with N-cadherin-presenting nano-matrices, suggesting heterophilic (N/E) interactions. However, cellular spreading in these cases occurred only at high densities of N-cadherin (i.e., >285 ligands/μm²). Overall, our approach using nano-patterned biomimetic surfaces provides a platform to further refine the roles of cadherins in tumor cell behavior and it revealed an intriguing flexibility of mutually compensating N- and E-cadherin interactions relevant for melanoma progression.

N-cadherin in cancer metastasis, its emerging role in haematological malignancies and potential as a therapeutic target in cancer

In many types of solid tumours, the aberrant expression of the cell adhesion molecule N-cadherin is a hallmark of epithelial-to-mesenchymal transition, resulting in the acquisition of an aggressive tumour phenotype. This transition endows tumour cells with the capacity to escape from the confines of the primary tumour and metastasise to secondary sites. In this review, we will discuss how N-cadherin actively promotes the metastatic behaviour of tumour cells, including its involvement in critical signalling pathways which mediate these events. In addition, we will explore the emerging role of N-cadherin in haematological malignancies, including bone marrow homing and microenvironmental protection to anti-cancer agents. Finally, we will discuss the evidence that N-cadherin may be a viable therapeutic target to inhibit cancer metastasis and increase tumour cell sensitivity to existing anti-cancer therapies.

Telomerase reverse transcriptase promoter mutations and solar elastosis in cutaneous melanoma

The aims of this study were to assess the prognostic potential of solar elastosis grading and telomerase reverse transcriptase (TERT) promoter mutations (TERTp) in melanoma and to evaluate whether an association between solar elastosis and TERTp exists. Solar elastosis in the dermis was evaluated in hematoxylin and eosin-stained whole slides from 486 malignant melanomas. Pyrosequencing was used to detect TERTp in 189 samples. There was no association between solar elastosis and TERTp (P=0.3). Severe elastosis was associated with older age (P<0.0001), ulceration (P=0.03), and location in the head/neck region (P<0.0001). The absence of elastosis was associated with younger age (P<0.0001), benign nevus remnants (P=0.001), and a positive BRAF V600E expression (P<0.0001). Severe elastosis predicted a worse relapse-free survival (hazard ratio: 2.18; 95% confidence interval: 1.30-3.64; P=0.003). However, it was not independent of age. TERTp was not associated with any adverse prognostic or clinicopathological outcome, nor any mitogen-activated protein kinase-related protein expressions. However, at a cutoff corresponding to the sensitivity of Sanger sequencing, TERTp predicted melanoma-specific death independently of age, and was associated with Breslow thickness, ulceration, tumor stage at diagnosis, BRAF V600E oncoprotein, and absence of p16 expression. In conclusion, TERTp were not related to severe elastosis and may thus be triggered by both chronic and acute intermittent sun exposure, the latter not visible on ordinary hematoxylin and eosin-stained slides. Neither TERTp nor severe elastosis predicted an adverse outcome in melanoma. An absence of elastosis was seen in younger melanoma patients and may be used to select those melanomas originating in a nevus, which often harbors a BRAF mutation.

Itraconazole treatment of primary malignant melanoma of the vagina evaluated using positron emission tomography and tissue cDNA microarray: a case report

BACKGROUND

Primary malignant melanoma of the vagina is extremely rare, with a poorer prognosis than cutaneous malignant melanoma. Previous studies have explored the repurposing of itraconazole, a common oral anti-fungal agent, for the treatment of various cancers. Here, we describe a patient with metastatic, unresectable vaginal malignant melanoma treated with 200 mg oral itraconazole twice a day in a clinical window-of-opportunity trial.

CASE PRESENTATION

A 64-year-old Japanese woman with vaginal and inguinal tumours was referred to our institution. On the basis of an initial diagnosis of vaginal cancer metastatic to the inguinal lymph nodes, we treated her with itraconazole in a clinical trial until the biopsy and imaging study results were obtained. During this period, biopsies were performed three times, and 18F-fluoro-deoxyglucose positron emission tomography (FDG/PET)-computed tomography (CT) was performed twice. Biopsy results confirmed the diagnosis of primary malignant melanoma of the vagina. Imaging studies revealed metastases to multiple sites, including the brain, for which she underwent gamma-knife radiosurgery. During the window period before nivolumab initiation, the patient received itraconazole for 30 days. Within a week of itraconazole initiation, pain in the inguinal nodes was ameliorated. PET-CT on days 6 and 30 showed a reduction in tumour size and FDG uptake, respectively. The biopsied specimens obtained on days 1, 13, and 30 were subjected to cDNA microarray analysis, which revealed a 100-fold downregulation in the transcription of four genes: STATH, EEF1A2, TTR, and CDH2. After 12 weeks of nivolumab administration, she developed progressive disease and grade 3 immune-related hepatitis. Discontinuation of nivolumab resulted in the occurrence of left pelvic and inguinal pain. Following re-challenge with itraconazole, the patient has not reported any pain for 4 months.

CONCLUSION

The findings of this case suggest that itraconazole is a potential effective treatment option for primary malignant melanoma of the vagina. Moreover, we identified potential itraconazole target genes, which could help elucidate the mechanism underlying this disease and potentially aid in the development of new therapeutic agents.

Cypripedin diminishes an epithelial-to-mesenchymal transition in non-small cell lung cancer cells through suppression of Akt/GSK-3β signalling

Lung cancer appears to have the highest rate of mortality among cancers due to its metastasis capability. To achieve metastasis, cancer cells acquire the ability to undergo a switch from epithelial to mesenchymal behaviour, termed the epithelial-to-mesenchymal transition (EMT), which is associated with poor clinical outcomes. Drug discovery attempts have been made to find potent compounds that will suppress EMT. Cypripedin, a phenanthrenequinone isolated from Thai orchid, Dendrobium densiflorum, exhibits diverse pharmacological activities. In this study, we found that cypripedin attenuated typical mesenchymal phenotypes, including migratory behaviour, of non-small cell lung cancer H460 cells, with a significant reduction of actin stress fibres and focal adhesion and with weakened anchorage-independent growth. Western blot analysis revealed that the negative activity of this compound on EMT was a result of the down-regulation of the EMT markers Slug, N-Cadherin and Vimentin, which was due to ATP-dependent tyrosine kinase (Akt) inactivation. As a consequence, the increase in the Slug degradation rate via a ubiquitin-proteasomal mechanism was encouraged. The observation in another lung cancer H23 cell line also supported this finding, indicating that cypripedin exhibits a promising pharmacological action on lung cancer metastasis that could provide scientific evidence for the further development of this compound.

Loss of E-cadherin as Part of a Migratory Phenotype in Melanoma Is Associated With Ulceration

It has been suggested that embryogenic properties of migratory cells are reactivated during wound healing and metastasis in adults. This might explain the association between wound-induced inflammation and poor survival in patients with ulcerated melanoma. Linking inflammation with a migratory phenotype, we characterize the infiltration of innate inflammatory cells, loss of cell-to-cell adhesion (E-cadherin), factors associated with extracellular matrix degradation [matrix metalloproteinase-9 (MMP-9), and neutrophil elastase (NE)], and spindle-shaped cell morphology, between ulcerated (n = 179) and nonulcerated (n = 206) melanoma. In addition, the presence of "extravascular migratory metastasis" (angiotropism) and tumor-vessel density were evaluated as important factors for tumor cell dispersal in ulcerated melanoma. We showed a correlation between expression of the granulocyte marker cd66b+ and the expression of NE and MMP-9, reflecting activated neutrophils. Ulcerated melanoma correlated with a low global E-cadherin score (P = 0.041) and weak-spot score (P = 0.0004). Thus, 28% of the nonulcerated, 42% of the minimally/moderately ulcerated melanoma, and 53% of the excessively ulcerated melanoma presented low scores as opposed to a high E-cadherin score. In addition, the presence of ulceration was correlated with angiotropism (P < 0.0001) and spindle-shaped morphology (P = 0.021). There were no differences in MMP-9 expression or intratumoral vessel density between the ulcerated and nonulcerated group. In conclusion, expression of migratory cell properties showed a highly heterogeneous pattern, which was associated with ulcerated areas and inflammatory cells, in general and with neutrophils in particular. We, therefore, suggest that wound-associated inflammation may be involved in the induction of migratory cell transition and tumor cell dispersal in ulcerated melanoma.

Neural crest and cancer: Divergent travelers on similar paths

Neural crest cells are multipotent progenitors that dynamically interpret diverse microenvironments to migrate significant distances as a loosely associated collective and contribute to many tissues in the developing vertebrate embryo. Uncovering details of neural crest migration has helped to inform a general understanding of collective cell migration, including that which occurs during cancer metastasis. Here, we discuss several commonalities and differences of neural crest and cancer cell migration and behavior. First, we focus on some of the molecular pathways required for the initial specification and potency of neural crest cells and the roles of many of these pathways in cancer progression. We also describe epithelial-to-mesenchymal transition, which plays a critical role in initiating both neural crest migration and cancer metastasis. Finally, we evaluate studies that demonstrate myriad forms of cell-cell and cell-environment communication during neural crest and cancer collective migration to highlight the remarkable similarities in their molecular and cell biological regulation.

Growth Hormone and the Epithelial-to-Mesenchymal Transition

CONTEXT

Previous studies have implicated growth hormone (GH) in the progression of several cancers, including breast, colorectal, and pancreatic. A mechanism by which GH may play this role in cancer is through the induction of the epithelial-to-mesenchymal transition (EMT). During the EMT process, epithelial cells lose their defining phenotypes, causing loss of cellular adhesion and increased cell migration. This review aims to carefully summarize the previous two decades of research that points to GH as an initiator of EMT, in both cancerous and noncancerous tissues.

EVIDENCE ACQUISITION

Sources were collected using PubMed and Google Scholar search engines by using specific GH- and/or EMT-related terms. Identified manuscripts were selected for further analysis based on presentation of GH-induced molecular markers of the EMT process in vivo or in vitro.

EVIDENCE SYNTHESIS

Cellular mechanisms involved in GH-induced EMT are the focus of this review, both in cancerous and noncancerous epithelial cells.

CONCLUSIONS

Our findings suggest that a myriad of molecular mechanisms are induced by GH that cause EMT and may point to potential therapeutic use of GH antagonists or any downregulator of GH action in EMT-related disease.

[Cadherin switching induced by P120-catenin can promote the migration and invasion of oral squamous cell cancer cells]

OBJECTIVE

The main goal is to investigate the role of P120-catenin (P120ctn) in cadherin switching, as well as migration and invasion, of oral squamous cell cancer (OSCC) cells.

METHODS

The plasmid pGFP-V-RS-P120ctn shRNA was used to transfect TSCCA cells and significantly reduce the expression of P120ctn in these cells. Real-time fluorescent quantitative polymerase chain reaction and Western blot were conducted to determine the mRNA and protein expression levels of P120ctn, E-cadherin (E-cad), and N-cadherin (N-cad). By contrast, the Transwell cell invasion and cell migration assay was used to determine the invasion and migration capacities before and after the transfection.

RESULTS

After the plasmid pGFP-V-RS-P120ctn shRNA was transfected into the TSCCA cells, we found that as the P120ctn expression significantly decreased, E-cad mRNA and protein expression decreased significantly. Moreover, N-cad mRNA and protein expression increased significantly (P<0.05). Lastly, the cell migration and invasion capacities were augmented significantly (P<0.05).

CONCLUSIONS

In OSCC cells, P120ctn may be involved in cadherin switching and promote metastasis and invasion.

Future of circulating tumor cells in the melanoma clinical and research laboratory settings

Circulating tumor cells (CTC) have become a field of interest for oncologists based on the premise that they constitute the underpinning for metastatic dissemination. The lethal nature of cancer is no longer attributed to solid tumor formation, but rather to the process of metastasis; shifting the focus of current studies towards the isolation and identification of metastatic progenitors, such as CTCs. CTCs originate from primary tumor masses that undergo morphologic and genetic alterations, which involve the release of mesenchymal-like cancer cells into the bloodstream, capable of invading nearby tissues for secondary tumor development. Cancerous cells contained in the primary tumor mass acquire the motile mesenchymal phenotype as a result of the Epithelial-to-Mesenchymal Transition, where substantial variations in protein expression and signaling pathways take place. CTCs that migrate from the primary tumor, intravasate into the systemic vasculature, are transported through the bloodstream, and invade tissues and organs suitable for secondary tumor development. While only a limited number of CTCs are viable in the bloodstream, their ability to elude the immune system, evade apoptosis and successfully metastasize at secondary tumor sites, makes CTCs promising candidates for unraveling the triggers that initiates the metastatic process. In this article, these subjects are explored in greater depth to elucidate the potential use of CTCs in the detection, disease staging and management of metastatic melanoma.

AHNAK is downregulated in melanoma, predicts poor outcome, and may be required for the expression of functional cadherin-1

The aim of this study was to further our understanding of the transformation process by identifying differentially expressed proteins in melanocytes compared with melanoma cell lines. Tandem mass spectrometry incorporating iTRAQ reagents was used as a screen to identify and comparatively quantify the expression of proteins in membrane-enriched samples isolated from primary human melanocytes or three melanoma cells lines. Real-time PCR was used to validate significant hits. Immunohistochemistry was used to validate the expression of proteins of interest in melanocytes in human skin and in melanoma-infiltrated lymph nodes. Publically available databases were examined to assess mRNA expression and correlation to patient outcome in a larger cohort of samples. Finally, preliminary functional studies were carried out using siRNAs to reduce the expression of a protein of interest in primary melanocytes and in a keratinocyte cell line. Two proteins, AHNAK and ANXA2, were significantly downregulated in the melanoma cell lines compared with melanocytes. Downregulation was confirmed in tumor cells in a subset of human melanoma-infiltrated human lymph nodes compared with melanocytes in human skin. Examination of Gene Expression Omnibus database data sets suggests that downregulation of AHNAK mRNA and mutation of the AHNAK gene are common in metastatic melanoma and correlates to a poor outcome. Knockdown of AHNAK in primary melanocytes and in a keratinocyte cell line led to a reduction in detectable cadherin-1. This is the first report that we are aware of which correlates a loss of AHNAK with melanoma and poor patient outcome. We hypothesize that AHNAK is required for the expression of functional cadherin-1.

The Danish Melanoma Database

AIM OF DATABASE

The aim of the database is to monitor and improve the treatment and survival of melanoma patients.

STUDY POPULATION

All Danish patients with cutaneous melanoma and in situ melanomas must be registered in the Danish Melanoma Database (DMD). In 2014, 2,525 patients with invasive melanoma and 780 with in situ tumors were registered. The coverage is currently 93% compared with the Danish Pathology Register.

MAIN VARIABLES

The main variables include demographic, clinical, and pathological characteristics, including Breslow's tumor thickness, ± ulceration, mitoses, and tumor-node-metastasis stage. Information about the date of diagnosis, treatment, type of surgery, including safety margins, results of lymphoscintigraphy in patients for whom this was indicated (tumors > T1a), results of sentinel node biopsy, pathological evaluation hereof, and follow-up information, including recurrence, nature, and treatment hereof is registered. In case of death, the cause and date are included. Currently, all data are entered manually; however, data catchment from the existing registries is planned to be included shortly.

DESCRIPTIVE DATA

The DMD is an old research database, but new as a clinical quality register. The coverage is high, and the performance in the five Danish regions is quite similar due to strong adherence to guidelines provided by the Danish Melanoma Group. The list of monitored indicators is constantly expanding, and annual quality reports are issued. Several important scientific studies are based on DMD data.

CONCLUSION

DMD holds unique detailed information about tumor characteristics, the surgical treatment, and follow-up of Danish melanoma patients. Registration and monitoring is currently expanding to encompass even more clinical parameters to benefit both patient treatment and research.

Prognostic significance of immunohistochemical epithelial–mesenchymal transition markers in skin melanoma patients

Aim: To investigate secreted protein acidic and rich in cystein (SPARC) and neural cadherin (NCAD), which are associated with epithelial–mesenchymal transition in primary skin melanoma and nodal metastases and their prognostic impact in melanoma patients. Methods: Expression of proteins was assessed by immunochemistry in archival paraffin samples from 103 primary melanoma tumors and 16 nodal metastases. Results: Increased expression of SPARC and NCAD in primary skin melanoma was associated with decreased overall survival, adverse clinicopathological features and particularly with microsatellitosis (SPARC) and ulceration (NCAD). In univariate Cox regression analysis, both biomarkers were significantly associated with the risk of death; the multivariate Cox regression analysis identified no significance. Conclusion: The most important result of our study was that we confirmed the strict correlation between SPARC and NCAD expression and clinicopathological parameters related with melanoma progression, which is a specific clinical equivalent of the molecular mechanisms of epithelial–mesenchymal transition process and confirms its key role in the disease outcome.

Histone deacetylase inhibitors induce invasion of human melanoma cells in vitro via differential regulation of N-cadherin expression and RhoA activity

Background

Histone deacetylase inhibitors (HDACi) exert multiple cytotoxic actions on cancer cells. Currently, different synthetic HDACi are in clinical use or clinical trials; nevertheless, since both pro-invasive and anti-invasive activities have been described, there is some controversy about the effect of HDACi on melanoma cells.

Methods

Matrigel and Collagen invasion assays were performed to evaluate the effect of several HDACi (Butyrate, Trichostatin A, Valproic acid and Vorinostat) on two human melanoma cell line invasion (A375 and HT-144). The expression of N- and E-Cadherin and the activity of the RhoA GTPase were analyzed to elucidate the mechanisms involved in the HDACi activity.

Results

HDACi showed a pro-invasive effect on melanoma cells in vitro. This effect was accompanied by an up-regulation of N-cadherin expression and an inhibition of RhoA activity. Moreover, the down-regulation of N-cadherin through blocking antibodies or siRNA abrogated the pro-invasive effect of the HDACi and, additionally, the inhibition of the Rho/ROCK pathway led to an increase of melanoma cell invasion similar to that observed with the HDACi treatments.

Conclusion

These results suggest a role of N-cadherin and RhoA in HDACi induced invasion and call into question the suitability of some HDACi as antitumor agents for melanoma patients.

Dermal fibroblasts induce cell cycle arrest and block epithelial-mesenchymal transition to inhibit the early stage melanoma development

Stromal fibroblasts are an integral part of the tumor stroma and constantly interact with cancer cells to promote their initiation and progression. However, the role and function of dermal fibroblasts during the early stage of melanoma development remain poorly understood. We, therefore, designed a novel genetic approach to deactivate stromal fibroblasts at the onset of melanoma formation by targeted ablation of β-catenin. To our surprise, melanoma tumors formed from β-catenin-deficient group (B16F10 mixed with β-catenin-deficient fibroblasts) appeared earlier than tumors formed from control group (B16F10 mixed with normal dermal fibroblasts). At the end point when tumors were collected, mutant tumors were bigger and heavier than control tumors. Further analysis showed that there were fewer amounts of stromal fibroblasts and myofibroblasts inside mutant tumor stroma. Melanoma tumors from control group showed reduced proliferation, down-regulated expression of cyclin D1 and increased expression of cyclin-dependent kinase inhibitor p16, suggesting dermal fibroblasts blocked the onset of melanoma tumor formation by inducing a cell cycle arrest in B16F10 melanoma cells. Furthermore, we discovered that dermal fibroblasts prevented epithelial-mesenchymal transition in melanoma cells. Overall, our findings demonstrated that dermal fibroblasts crosstalk with melanoma cells to regulate in vivo tumor development via multiple mechanisms, and the outcomes of their reciprocal interactions depend on activation states of stromal fibroblasts and stages of melanoma development.

Expression of E-, P- and N-Cadherin and Its Clinical Significance in Cervical Squamous Cell Carcinoma and Precancerous Lesions

Aberrant expression of classical cadherins has been observed in tumor invasion and metastasis, but its involvement in cervical carcinogenesis and cancer progression is not clear. We investigated E-, P- and N-cadherin expression and its significance in cervical squamous cell carcinoma (SCC) and cervical intraepithelial neoplasia (CIN). This retrospective study enrolled 508 patients admitted to Women's Hospital, School of Medicine, Zhejiang University with cervical lesions between January 2006 and December 2010. Immunochemical staining was performed in 98 samples of normal cervical epithelium (NC), 283 of CIN, and 127 of early-stage SCC. The association of cadherin staining with clinical characteristics and survival of the patients was evaluated by univariate and multivariate analysis. We found gradients of decreasing E-cadherin expression and increasing P-cadherin expression from NC through CIN to SCC. Aberrant E-cadherin and P-cadherin expression were significantly associated with clinical parameters indicating poor prognosis and shorter patient survival. Interestingly, we found very low levels of positive N-cadherin expression in CIN and SCC tissues that were not related to CIN or cancer. Pearson chi-square tests showed that E-cadherin expression in SCC was inversely correlated with P-cadherin expression (E-P switch), and was not correlated with N-cadherin expression. More important, patients with tissues exhibiting an E-P switch in expression had highly aggressive phenotypes and poorer prognosis than those without E-P switch expression. Our findings suggest that E-cadherin and P-cadherin, but not N-cadherin staining, might be useful in diagnosing CIN and for predicting prognosis in patients with early-stage SCC.

Multiparameter analysis of naevi and primary melanomas identifies a subset of naevi with elevated markers of transformation

Here we have carried out a multiparameter analysis using a panel of 28 immunohistochemical markers to identify markers of transformation from benign and dysplastic naevus to primary melanoma in three separate cohorts totalling 279 lesions. We have identified a set of eight markers that distinguish naevi from melanoma. None of markers or parameters assessed differentiated benign from dysplastic naevi. Indeed, the naevi clustered tightly in terms of their immunostaining patterns whereas primary melanomas showed more diverse staining patterns. A small subset of histopathologically benign lesions had elevated levels of multiple markers associated with melanoma, suggesting that these represent naevi with an increased potential for transformation to melanoma.

DNA methylation-induced E-cadherin silencing is correlated with the clinicopathological features of melanoma

E-cadherin, a calcium-dependent cell-cell adhesion molecule, has an important role in epithelial cell function, maintenance of tissue architecture and cancer suppression. Loss of E-cadherin promotes tumor metastatic dissemination and predicts poor prognosis. The present study investigated the clinicopathological significance of E-cadherin expression in cutaneous, mucosal and uveal melanoma related to epigenetic mechanisms that may contribute to E-cadherin silencing. E-cadherin expression was reduced in 55/130 cutaneous (42.3%), 49/82 mucosal (59.7%) and 36/64 uveal (56.2%) melanoma samples as compared to normal skin controls and was inversely associated with promoter methylation. Of the 10 different CpG sites studied (nt 863, 865, 873, 879, 887, 892, 901, 918, 920 and 940), two sites (nt 892 and 940) were 90-100% methylated in all the melanoma specimens examined and the other ones were partially methylated (range, 53-86%). In contrast, the methylation rate of the E-cadherin gene was low in normal tissues (range, 5-24%). In all the three types of melanoma studied, a significant correlation was found between reduced levels of E-cadherin and reduced survival, high mitotic index and metastasis, accounting for the predilection of lymph nodal localization. In cutaneous and mucosal melanoma, low E-cadherin expression was positively correlated also with head/neck localization and ulceration. A high frequency of reduced E-cadherin levels occurred in choroid melanomas. In vitro experiments showed that E-cadherin transcription was restored following 5-aza-2'-deoxycytidine (5-aza-dC) treatment or DNMT1 silencing and was negatively correlated with the invasive potential of melanoma cells. The significant relationship between E-cadherin silencing and several poor prognostic factors indicates that this adhesion molecule may play an important role in melanomagenesis. Therefore, the inverse association of E-cadherin expression with promoter methylation raises the intriguing possibility that reactivation of E-cadherin expression through promoter demethylation may represent a potential therapeutic strategy for the treatment of melanoma.

BRAF and epithelial-mesenchymal transition in primary cutaneous melanoma: a role for Snail and E-cadherin?

In vitro studies in melanoma indicate that up-regulation of the transcriptional repressor Snail occurs with a concomitant decrease of its target E-cadherin, both hallmarks of epithelial-mesenchymal transition-an association not established in vivo. We sought to elucidate the relationship between BRAF, Snail, E-cadherin, and established histopathologic prognosticators in primary cutaneous melanoma. Archived annotated samples with a diagnosis of primary cutaneous melanoma were retrieved (n = 68 cases; 34 BRAF mutant and 34 BRAF wild type) and immunohistochemically stained for Snail and E-cadherin protein expression. A semiquantitative scoring system was used. Multivariate logistic analysis was used to control confounders of BRAF. Snail expression was significantly associated only with ulceration (42% versus 13%; P = .02). E-cadherin expression was present in 26% of BRAF mutant and 71% of BRAF wild-type cases (P = .0003). Loss of E-cadherin expression was associated with female sex (60% versus 34%; P = .05), BRAF mutation (74% versus 29%; P = .0003), thickness greater than or equal to 1 mm (68% versus 32%; P = .004), mitosis (63% versus 25%; P = .007), and ulceration (75% versus 44%; P = .05). BRAF mutation was associated with male sex (60% versus 30%; P = .02), Breslow thickness (P = .007), thickness greater than or equal to 1 mm (68% versus 29%; P = .002), and ulceration (75% versus 42%; P = .02). Snail expression did not correlate with loss of E-cadherin expression (47% versus 53%; P = .79). After controlling for potential confounding, BRAF mutation was associated with loss of E-cadherin (adjusted odds ratio, 8.332; 95% confidence interval, 2.257-30.757; P = .0015) and Breslow thickness greater than 1 mm (adjusted odds ratio, 7.360; 95% confidence interval, 1.534-35.318; P = .0126). Our findings, indicating that mutant BRAF represses E-cadherin expression, implicating a catalytic role for BRAF in epithelial-mesenchymal transition.

Perspective of Targeting Cancer-Associated Fibroblasts in Melanoma

Melanoma is known as an exceptionally aggressive and treatment-resistant human cancer. Although a great deal of progress has been made in the past decade, including the development of immunotherapy using immune checkpoint inhibitors and targeted therapy using BRAF, MEK or KIT inhibitors, treatment for unresectable stage III, stage IV, and recurrent melanoma is still challenging with limited response rate, severe side effects and poor prognosis, highlighting an urgent need for discovering and designing more effective approaches to conquer melanoma. Melanoma is not only driven by malignant melanocytes, but also by the altered communication between neoplastic cells and non-malignant cell populations, including fibroblasts, endothelial and inflammatory cells, in the tumor stroma. Infiltrated and surrounding fibroblasts, also known as cancer-associated fibroblasts (CAFs), exhibit both phenotypical and physiological differences compared to normal dermal fibroblasts. They acquire properties of myofibroblasts, remodel the extracellular matrix (ECM) and architecture of the diseased tissue and secrete chemical factors, which all together promote the transformation process by encouraging tumor growth, angiogenesis, inflammation and metastasis and contribute to drug resistance. A number of in vitro and in vivo experiments have shown that stromal fibroblasts promote melanoma cell proliferation and they have been targeted to suppress tumor growth effectively. Evidently, a combination therapy co-targeting tumor cells and stromal fibroblasts may provide promising strategies to improve therapeutic outcomes and overcome treatment resistance. A significant benefit of targeting CAFs is that the approach aims to create a tumor-resistant environment that inhibits growth of melanomas carrying different genetic mutations. However, the origin of CAFs and precise mechanisms by which CAFs contribute to melanoma progression and drug resistance remain poorly understood. In this review, we discuss the origin, activation and heterogeneity of CAFs in the melanoma tumor microenvironment and examine the contributions of stromal fibroblasts at different stages of melanoma development. We also highlight the recent progression in dissecting and characterizing how local fibroblasts become reprogrammed and build a dynamic yet optimal microenvironment for tumors to develop and metastasize. In addition, we review key developments in ongoing preclinical studies and clinical applications targeting CAFs and tumor-stroma interactions for melanoma treatment.

Molecular pathology of cutaneous melanoma

Cutaneous melanoma is associated with strong prognostic phenotypic features, such as gender, Breslow's thickness and ulceration, although the biological significance of these variables is largely unknown. It is likely that these features are surrogates of important biological events rather than directly promoting cutaneous melanoma progression. In this article, we address the molecular mechanisms that drive these phenotypic changes. Furthermore, we present a comprehensive overview of recurrent genetic abnormalities, both germline and somatic, in relation to cutaneous melanoma subtypes, ultraviolet exposure and anatomical localization, as well as pre-existing and targeted therapy-induced mutations that may contribute to resistance. The increasing knowledge of critically important oncogenes and tumor-suppressor genes is promoting a transition in melanoma diagnosis, in which single-gene testing will be replaced by multiplex and multidimensional analyses that combine classical histopathological characteristics with the molecular profile for the prognostication and selection of melanoma therapy.

Circulating melanoma cells in the diagnosis and monitoring of melanoma: an appraisal of clinical potential

Circulating melanoma cells (CMCs) are thought to be the foundation for metastatic disease, which makes this cancer especially lethal. Cancer cells contained in the primary tumor undergo genotypic and phenotypic changes leading to an epithelial-to-mesenchymal transition, during which numerous changes occur in signaling pathways and proteins in the cells. CMCs are then shed off or migrate from the primary tumor and intravasate the vasculature system. A few CMCs are able to survive in the circulation through expression of a variety of genes and also by evading immune system recognition to establish metastases at distant sites after extravasating from the vessels. The presence of CMCs in the blood of a melanoma patient can be used for disease staging, predicting metastasis development, and evaluating the efficacy of therapeutic agents. Overall survival and disease-free duration can also be correlated with the presence of CMCs. Finally, analysis of CMCs for druggable therapeutic gene targets could lead to the development of personalized treatment regimens to prevent metastasis. Thus, the study of CMCs shows promise for the detection, staging, and monitoring of disease treatment, as well as for determination of prognosis and predicting overall disease-free survival. These are the areas reviewed in this article.

MiR-199a-5p loss up-regulated DDR1 aggravated colorectal cancer by activating epithelial-to-mesenchymal transition related signaling

BACKGROUND

Discoidin domain receptors1 (DDR1) is associated with tumor progression, and its dysregulated expression has been observed in many cancers.

AIM

We aim to explore molecular mechanism underlying the role of DDR1 in colorectal cancer development.

METHODS

Immunohistochemistry and Western blot were applied to examine the DDR1 expression. Real-time RT-PCR and Western blot were performed to determine the expression of miR-199a-5p and DDR1. Luciferase reporter assay was used to determine whether DDR1 was a target of miR-199a-5p. Effects of miR-199a-5p and DDR1 on colorectal cell proliferation, colony formation, cell cycle progression, invasion and migration were then investigated. Western blot was used to determine the relative signal pathways.

RESULTS

Increased DDR1 and decreased miR-199a-5p expression coexisted in CRC, knockdown of DDR1 or overexpression of miR-199a-5p both resulted in reduced colony formation, invasive and migratory capabilities of human CRC LOVE1 and LOVO cells. It was also found that overexpression of miR-199a-5p led to decreased DDR1, MMP2, N-cadherin and vimentin expression and increased E-cadherin expression in both CRC cell lines. However, down-regulation of miR-199a-5p resulted in the opposite effects. Dual luciferase reporter assay confirmed that miR-199a-5p could directly target DDR1 through binding to its 3'-UTR.

CONCLUSIONS

Our findings indicated that up-regulation of DDR1 induced by miR-199a-5p down-regulation may contribute to the development and progression of CRC, and this effect may be associated with increased invasiveness, at least in part, via activating the EMT-related signaling.

KIT is a frequent target for epigenetic silencing in cutaneous melanoma

The receptor tyrosine kinase KIT and its ligand, stem cell factor (SCF), are essential for the proliferation and survival of normal melanocytes. In melanomas arising on mucosal, acral, and chronically sun-damaged skin, activating KIT mutations have been identified as oncogenic drivers and potent therapeutic targets. Through an initial whole-genome screen for aberrant promoter methylation in melanoma, we identified the KIT promoter as a target for hypermethylation in 43/110 melanoma cell lines, and in 3/12 primary and 11/29 metastatic cutaneous melanomas. Methylation density at the KIT promoter correlated inversely with promoter activity in vitro and in vivo, and the expression of KIT was restored after treatment with the demethylating agent 5-aza-2'-deoxycytidine. Hypermethylation of KIT showed no direct or inverse correlations with well-documented melanoma drivers. Growth of melanoma cells in the presence of SCF led to reduced KIT expression and increased methylation density at the KIT promoter, suggesting that SCF may exert a selection pressure for the loss of KIT. The frequent loss of KIT in cutaneous melanoma by promoter hypermethylation suggests that distinct KIT signaling pathways have opposing roles in the pathogenesis of melanoma subtypes.