Stem cell properties in cell cultures from different stage of melanoma progression

The Interplay between Tumour Microenvironment Components in Malignant Melanoma

Malignant melanoma has shown an increasing incidence during the last two decades, exhibiting a large spectrum of locations and clinicopathological characteristics. Although current histopathological, biochemical, immunohistochemical, and molecular methods provide a deep insight into its biological behaviour and outcome, melanoma is still an unpredictable disease, with poor outcome. This review of the literature is aimed at updating the knowledge regarding melanoma’s clinicopathological and molecular hallmarks, including its heterogeneity and plasticity, involving cancer stem cells population. A special focus is given on the interplay between different cellular components and their secretion products in melanoma, considering its contribution to tumour progression, invasion, metastasis, recurrences, and resistance to classical therapy. Furthermore, the influences of the specific tumour microenvironment or “inflammasome”, its association with adipose tissue products, including the release of “extracellular vesicles”, and distinct microbiota are currently studied, considering their influences on diagnosis and prognosis. An insight into melanoma’s particular features may reveal new molecular pathways which may be exploited in order to develop innovative therapeutic approaches or tailored therapy.

Neuroendocrine Factors in Melanoma Pathogenesis

Simple Summary

Melanoma is a very aggressive and fatal malignant tumor. While curable if diagnosed in its early stages, advanced melanoma, despite the complex therapeutic approaches, is associated with one of the highest mortality rates. Hence, more and more studies have focused on mechanisms that may contribute to melanoma development and progression. Various studies suggest a role played by neuroendocrine factors which can act directly on tumor cells, modulating their proliferation and metastasis capability, or indirectly through immune or inflammatory processes that impact disease progression. However, there are still multiple areas to explore and numerous unknown features to uncover. A detailed exploration of the mechanisms by which neuroendocrine factors can influence the clinical course of the disease could open up new areas of biomedical research and may lead to the development of new therapeutic approaches in melanoma.

Abstract

Melanoma is one of the most aggressive skin cancers with a sharp rise in incidence in the last decades, especially in young people. Recognized as a significant public health issue, melanoma is studied with increasing interest as new discoveries in molecular signaling and receptor modulation unlock innovative treatment options. Stress exposure is recognized as an important component in the immune-inflammatory interplay that can alter the progression of melanoma by regulating the release of neuroendocrine factors. Various neurotransmitters, such as catecholamines, glutamate, serotonin, or cannabinoids have also been assessed in experimental studies for their involvement in the biology of melanoma. Alpha-MSH and other neurohormones, as well as neuropeptides including substance P, CGRP, enkephalin, beta-endorphin, and even cellular and molecular agents (mast cells and nitric oxide, respectively), have all been implicated as potential factors in the development, growth, invasion, and dissemination of melanoma in a variety of in vitro and in vivo studies. In this review, we provide an overview of current evidence regarding the intricate effects of neuroendocrine factors in melanoma, including data reported in recent clinical trials, exploring the mechanisms involved, signaling pathways, and the recorded range of effects.

Zeaxanthin-Rich Extract from Superfood Lycium barbarum Selectively Modulates the Cellular Adhesion and MAPK Signaling in Melanoma versus Normal Skin Cells In Vitro

The concern for implementing bioactive nutraceuticals in antioxidant-related therapies is of great importance for skin homeostasis in benign or malignant diseases. In order to elucidate some novel insights of Lycium barbarum (Goji berry) activity on skin cells, the present study focused on its active compound zeaxanthin. By targeting the stemness markers CD44 and CD105, with deep implications in skin oxidative stress mechanisms, we revealed, for the first time, selectivity in zeaxanthin activity. When applied in vitro on BJ human fibroblast cell line versus the A375 malignant melanoma cells, despite the moderate cytotoxicity, the zeaxanthin-rich extracts 1 and 2 were able to downregulate significantly the CD44 and CD105 membrane expression and extracellular secretion in A375, and to upregulate them in BJ cells. At mechanistic level, the present study is the first to demonstrate that the zeaxanthin-rich Goji extracts are able to influence selectively the mitogen-activated protein kinases (MAPK): ERK, JNK and p38 in normal BJ versus tumor-derived A375 skin cells. These results point out towards the applications of zeaxanthin from L. barbarum as a cytoprotective agent in normal skin and raises questions about its use as an antitumor prodrug alone or in combination with standard therapy.

Characteristics of Mel Ibr Melanoma Line Subclone after Treatment with Chicken Embryo Extract

We continue analysis of the phenotype of human melanoma cell Mel Ibr subclone obtained previously by treatment of the parental cell line by chicken embryo extract. The present study is focused on detection of markers of epithelial-mesenchymal transition that determine enhanced metastatic and invasive potential of malignant tumors of various locations. Analysis of the expression of E-cadherin and vimentin genes in the subclone and parental cells detected activation of epithelial-mesenchymal transition in the subclone. Immunological markers CD90, CD271, and CD95 were present in the parental population, but were not detected on the subclone cells. In contrast to the parental line, cells of the analyzed subclone retain viability in serum-free medium and formed vessel-like structures characteristic of vasculogenic mimicry.

Desmoplastic melanoma: a challenge for the oncologist

Aim: To evaluate clinical, pathologic and genetic features of desmoplastic melanoma (DM). Materials & methods: Analysis of all DM records from 1991 to 2015. Results: The most common location of DMs was the head and neck (69%); median age and follow-up were 60.5 and 7.3 years, respectively. A familial predisposition for DMs and others malignancies was analyzed. Thin Breslow thickness (<4.5 mm) was associated with an intraepidermal component or a previous lentigo maligna, whereas high Breslow thickness (>4.5 mm) was observed in ‘pure’ DM. Conclusion: DM could progress from an early phase, characterized by an intraepidermal component, to late phase, characterized by a dermal nodule. This hypothesis correlates with melanoma genetic and NF1 mutation, which could be an early event in the progression of DM.

Prognostic significance of nestin in primary malignant melanoma of the oral cavity

Several studies have examined the correlation between nestin expression and the degree of tumor invasion in cutaneous melanoma. However, no information has been reported on nestin in primary mucosal melanoma of the head and neck. The present study examined the expression and prognostic significance of nestin in patients with primary mucosal melanoma of the oral cavity. Nestin expression was examined immunohistochemically in 39 patients (six oral melanoma in-situ cases and 33 invasive oral melanoma cases) and analyzed for association with disease progression. Age, sex, anatomic site, stage, level of invasion, regional lymph node metastasis, surgical margin involvement, and treatment modality were also analyzed. In the 33 invasive melanoma cases, invasion depth correlated significantly with prognosis in univariate and multivariate analyses. High-intensity nestin staining was observed in 14 of the 33 cases and a high proportion of nestin-positive cells was observed in 16 cases. In stage III oral melanoma cases, nestin expression was not significantly associated with disease progression. However, in stage IV cases, both the intensity and the proportion of nestin expression were significantly associated with disease progression (P=0.022 and 0.005, respectively). In all 33 invasive cases, multivariate analyses showed that both the intensity and the proportion of nestin were significantly associated with a poor prognosis (P=0.014 and 0.009; hazard ratio, 3.59 and 4.05; 95% confidence interval, 1.29-9.98 and 1.42-11.56, respectively). In conclusion, nestin can be a valuable prognostic indicator in the advanced-stage (stage IV) cases of oral mucosal melanoma.

Evaluation of the expressions pattern of miR-10b, 21, 200c, 373 and 520c to find the correlation between epithelial-to-mesenchymal transition and melanoma stem cell potential in isolated cancer stem cells

Small non-coding RNAs named microRNAs (miRNAs) modulate some functions and signaling pathways in skin epithelial cells and melanocytes. They also function as oncogenes or tumor suppressors in malignancies and tumor metastasis. We investigated the expression patterns of miRNAs, including miR-10b, 21, 200c, 373 and 520c, which regulate epithelial-to-mesenchymal transition (EMT) and metastasis in isolated cancer stem cells (CSCs) and non- CSCs. Six melanoma cell lines were tested for the expressions of stem cell markers. Melanoma stem cells were enriched via fluorescence-activated cell sorting (FACS) using the CD133 cell surface marker or spheroid culture. They were then characterized based on colony and sphere formation, and the expressions of stemness and EMT regulator genes and their invasion potential were assessed using real-time qRT-PCR and invasion assay. Our results indicate that cells enriched via sphere formation expressed all the stemness-related genes and had an enhanced number of colonies, spheres and invaded cells compared to cells enriched using the CD133 cell surface marker. Moreover, miRNAs controlling metastasis increased in the melanospheres. This may be related to the involvement of CSCs in the metastatic process. However, this must be further confirmed through the application of knockdown experiments. The results show that sphere formation is a useful method for enriching melanoma stem cells. Melanospheres were found to upregulate miR-10b, 21, 200c, 373 and 520c, so we suggest that they may control both metastasis and stemness potential.

The role of stress and beta-adrenergic system in melanoma: current knowledge and possible therapeutic options

PURPOSE

The aim of the present review was to discuss recent findings on the role of beta-adrenergic system in melanoma, in order to provide information on the biological responses elicited by its activation and its potential application for melanoma treatment.

METHODS

A literature search was performed, and evidences regarding the involvement of stress and beta-adrenergic system in cancer and melanoma were found and discussed.

RESULTS

Our search pointed out that beta-adrenergic system is a key regulator of important biological processes involved in the onset and progression of some solid tumors. In the last decade, functional beta-adrenoceptors have been also identified on melanoma cells, as well as on their microenvironment cells. Similarly to other common cancers too, the activation of such adrenoceptors by catecholamines, usually released under stress conditions, has been found to trigger pro-tumorigenic pathways contributing to cell proliferation and motility, immune system regulation, apoptosis, epithelial-mesenchymal transition, invasion and neoangiogenesis.

CONCLUSIONS

The biological evidences we found clarify and sustain the clinical evidences reporting the involvement of chronic stress in melanoma onset and progression. In such scenario, it is conceivable that a therapeutic approach targeting beta-adrenergic system could constitute a novel and promising strategy for melanoma treatment.

DKK3 blocked translocation of β-catenin/EMT induced by hypoxia and improved gemcitabine therapeutic effect in pancreatic cancer Bxpc-3 cell

The Wnt/β-catenin signalling pathway is activated in pancreatic cancer initiation and progression. Dickkopf-related protein 3 (DKK3) is a member of the human Dickkopf family and an antagonist of Wnt ligand activity. However, the function of DKK3 in this pathway in pancreatic cancer is rarely known. We examined the expression of DKK3 in six human pancreatic cancer cell lines, 75 pancreatic cancer and 75 adjacent non-cancerous tissues. Dickkopf-related protein 3 was frequently silenced and methylation in pancreatic cancer cell lines (3/6). The expression of DKK3 was significantly lower in pancreatic cancer tissues than in adjacent normal pancreas tissues. Further, ectopic expression of DKK3 inhibits nuclear translocation of β-catenin induced by hypoxia in pancreatic cancer Bxpc-3 cell. The forced expression of DKK3 markedly suppressed migration and the stem cell-like phenotype of pancreatic cancer Bxpc-3 cell in hypoxic conditions through reversing epithelial-mesenchymal transition (EMT). The stable expression of DKK3 sensitizes pancreatic cancer Bxpc-3 cell to gemcitabine, delays tumour growth and augments gemcitabine therapeutic effect in pancreatic cancer xenotransplantation model. Thus, we conclude from our finding that DKK3 is a tumour suppressor and improved gemcitabine therapeutic effect through inducing apoptosis and regulating β-catenin/EMT signalling in pancreatic cancer Bxpc-3 cell.

The multifaceted role of CD146/MCAM in the promotion of melanoma progression

Human malignant melanoma is a common primary malignant cutaneous tumour derived from transformed epidermal melanocytes. Patients with melanoma have a high rate of mortality due to resistance to chemotherapeutic drugs, a major obstacle to a successful treatment. Several reports have suggested that CD146 plays an important role as a signalling molecule in human melanoma. This role includes CD146 as a participant in inflammation, differentiation, adhesion, tumourigenicity, metastasis, invasion and angiogenesis among other processes, which suggests that this molecule promotes the progression of human melanoma as a multifaceted regulator. In this article, we explore the effects and corresponding mechanisms with respect to the role of CD146/MUC18 in the promotion of human melanoma progression. Collectively, the studies indicated that targeting CD146, because it is a suitable marker of poor patient outcome, might be useful in the design of future strategies for the prevention and treatment of human melanoma.

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.

CD133⁺ melanoma subpopulation acquired resistance to caffeic acid phenethyl ester-induced apoptosis is attributed to the elevated expression of ABCB5: significance for melanoma treatment

According to the cancer stem-like cell (CSC) hypothesis, neoplastic clones are maintained by a small fraction of cells with stem cell properties. Also, melanoma resistance to chemo- and radiotherapy is thought to be attributed to melanoma stem-like cells (MSCs). Caffeic acid phenethyl ester (CAPE) is a bioactive molecule, whose antitumor activity is approved in different tumor types. CAPE induced both apoptosis and E2F1 expression in CD133(-), but not in CD133(+) melanoma subpopulations. The resistance of CD133(+) melanoma subpopulation is attributed to the enhanced drug efflux mediated by ATP-binding cassette sub-family B member 5 (ABCB5), since the knockdown of ABCB5 was found to sensitize CD133(+) cells to CAPE. CAPE-induced apoptosis is mediated by E2F1 as evidenced by the abrogation of apoptosis induced in response to the knockdown of E2F1. The functional analysis of E2F1 in CD133(+) melanoma subpopulation demonstrated the ability of E2F1 gene transfer to trigger apoptosis of CD133(+) cells and to enhance the activation of apoptosis signal-regulating kinase (ASK1), c-Jun N-terminal kinase and p38, and the DNA-binding activities of the transcription factors AP-1 and p53. Also, the induction of E2F1 expression was found to enhance the expression of the pro-apoptotic proteins Bax, Noxa and Puma, and to suppress the anti-apoptotic protein Mcl-1. Using specific pharmacological inhibitors we could demonstrate that E2F1 overcomes the chemo-resistance of MSCs/CD133(+) cells by a mechanism mediated by both mitochondrial dysregulation and ER-stress-dependent pathways. In conclusion, our data addresses the mechanisms of CAPE/E2F1-induced apoptosis of chemo-resistant CD133(+) melanoma subpopulation.

Should EMT of Cancer Cells Be Understood as Epithelial-Myeloid Transition?

Cancer cells express epithelial markers, and when progressing in malignancy they may express markers of the mesenchymal cell type. Therefore an epithelial-mesenchymal transition of the cancer cells is assumed. However the mesenchymal markers can equally well be interpreted as myeloid markers since they are common in both types of cell lineages. Moreover, cancer cells express multiple specific markers of the myeloid lineages thus giving rise to the hypothesis that the transition of cancer cells may be from epithelial to myeloid cells and not to mesenchymal cells. This interpretation would better explain why cancer cells, often already in their primary cancer site, frequently show properties common to those of macrophages, platelets and pre-/osteoclasts.