Human Cutaneous Melanoma Research Articles

The transmembrane protein LRIG1 triggers melanocytic tumor development following chemically induced skin carcinogenesis

The incidence of melanoma and nonmelanoma skin cancer has increased tremendously in recent years. Although novel treatment options have significantly improved patient outcomes, the prognosis for most patients with an advanced disease remains dismal. It is, thus, imperative to understand the molecular mechanisms involved in skin carcinogenesis in order to develop new targeted treatment strategies. Receptor tyrosine kinases (RTK) like the ERBB receptor family, including EGFR/ERBB1, ERBB2/NEU, ERBB3, and ERBB4, are important regulators of skin homeostasis and their dysregulation often results in cancer, which makes them attractive therapeutic targets. Members of the leucine‐rich repeats and immunoglobulin‐like domains protein family (LRIG1‐3) are ERBB regulators and thus potential therapeutic targets to manipulate ERBB receptors. Here, we analyzed the function of LRIG1 during chemically induced skin carcinogenesis in transgenic mice expressing LRIG1 in the skin under the control of the keratin 5 promoter (LRIG1‐TG mice). We observed a significant induction of melanocytic tumor formation in LRIG1‐TG mice and no difference in papilloma incidence between LRIG1‐TG and control mice. Our findings also revealed that LRIG1 affects ERBB signaling via decreased phosphorylation of EGFR and increased activation of the oncoprotein ERBB2 during skin carcinogenesis. The epidermal proliferation rate was significantly decreased during epidermal tumorigenesis under LRIG1 overexpression, and the apoptosis marker cleaved caspase 3 was significantly activated in the epidermis of transgenic LRIG1 mice. Additionally, we detected LRIG1 expression in human cutaneous squamous cell carcinoma and melanoma samples. Therefore, we depleted LRIG1 in human melanoma cells (A375) by CRISPR/Cas9 technology and found that this caused EGFR and ERBB3 downregulation in A375 LRIG1 knockout cells 6 h following stimulation with EGF. In conclusion, our study demonstrated that LRIG1‐TG mice develop melanocytic skin tumors during chemical skin carcinogenesis and a deletion of LRIG1 in human melanoma cells reduces EGFR and ERBB3 expression after EGF stimulation.

Interleukin-33 modulates immune responses in cutaneous melanoma in a context-specific way.

Controversial roles of interleukin-33 (IL-33) have been reported in melanoma from animal studies. We aimed to investigate the role of IL-33 in human cutaneous melanoma. RNA-seq data of 471 cases of cutaneous melanoma were retrieved from The Cancer Genome Atlas. The tumor microenvironment (TME) was deconstructed by the xCell algorithm using RNA-seq data. We evaluated the prognostic value of IL-33 and the relationship between IL-33 and immune components in TME. We also inferred the potential cellular sources of IL-33. All the analyses were conducted separately in three sub-cohorts, which are based on the biopsy sites of samples: primary melanoma; lymph node (LN) metastases; other metastases, including metastases to skin/soft tissue, or visceral sites. In the two metastasis sub-cohorts, IL-33 is associated with better prognosis and more active immune responses in the tumor. However, IL-33 is not a prognostic factor in the primary melanoma sub-cohort. Furthermore, we found that IL-33 is mainly derived from stromal cells in the metastasis sub-cohorts, and from epithelial cells/keratinocytes in the primary melanoma sub-cohort. These findings provide evidence for the context-specific anti-tumor effects of IL-33 in melanoma. And the distinct effects of IL-33 may be determined by the cellular sources of IL-33.

Cepharanthine as a Potential Novel Tumor-Regional Therapy in Treating Cutaneous Melanoma: Altering the Expression of Cathepsin B, Tumor Suppressor Genes and Autophagy-Related Proteins.

The incidence of primary cutaneous melanoma continues to increase annually and is one of the most aggressive malignancies in humans and need to develop more novel non-surgical therapies. Autophagy and cathepsin B targeted therapy was reported to improve melanoma treatment. Cepharanthine (CEP), a natural alkaloid extracted from the genus Cephalophyllum has been reported to have the function of inhibiting cancers. We found that CEP inhibited human primary cutaneous melanoma cells viability and proliferation in 24 h in vitro, and topical application or intra-tumoral injection of CEP decreased the growth of cutaneous melanoma in mice within 4 weeks. CEP preparations below 50% concentration did not induce skin irritation and allergy reaction on human skin in vivo. Primary cutaneous melanoma cells incubated with CEP, the expression of cathepsin B was decreased and the LC3-I and LC3-II expression changed in a dose-dependent manner, while p53, p21Cip1p, and p16Inka gene expression was up-regulated. We demonstrated the effects of CEP as a novel tumor-regional therapy for cutaneous melanoma and provided a preliminary research basis for future clinical treatment researches and the exploration of integrated treatments with systemic therapy, radiotherapy, and surgery for human primary cutaneous melanoma.

In Cellulo Evaluation of the Therapeutic Potential of NHC Platinum Compounds in Metastatic Cutaneous Melanoma.

We describe here the evaluation of the cytotoxic efficacy of two platinum (II) complexes bearing an N-heterocyclic carbene (NHC) ligand, a pyridine ligand and bromide or iodide ligands on a panel of human metastatic cutaneous melanoma cell lines representing different genetic subsets including BRAF-inhibitor-resistant cell lines, namely A375, SK-MEL-28, MeWo, HMCB, A375-R, SK-MEL-5-R and 501MEL-R. Cisplatin and dacarbazine were also studied for comparison purposes. Remarkably, the iodine-labelled Pt-NHC complex strongly inhibited proliferation of all tested melanoma cells after 1-h exposure, likely due to its rapid uptake by melanoma cells. The mechanism of this inhibitory activity involves the formation of DNA double-strand breaks and apoptosis. Considering the intrinsic chemoresistance of metastatic melanoma cells of current systemic treatments, these findings are promising and could give research opportunities in the future to improve the prognosis of patients suffering from unresectable metastatic melanoma that are not eligible or that do not respond to the most effective drugs available to date, namely BRAF inhibitors and the anti-PD-1 monoclonal antibody (mAb).

Pathogenic germline variants are associated with poor survival in stage III/IV melanoma patients

Patients with late stage resected cutaneous melanoma have poor overall survival (OS) and experience irreversible adverse events from systemic therapy. There is a clinical need to identify biomarkers to predict outcome. Performing germline/tumour whole-exome sequencing of 44 stage III/IV melanoma patients we identified pathogenic germline mutations in CDKN2A, CDK4, ATM, POLH, MRE11A, RECQL4 and XPC, affecting 7/44 patients. These mutations were associated with poor OS (p = 0.0082). We confirmed our findings in The Cancer Genome Atlas (TCGA) human skin cutaneous melanoma cohort where we identified pathogenic variants in 40/455 patients (p = 0.0203). Combining these cohorts (n = 499) further strengthened these findings showing germline carriers had worse OS (p = 0.0009). Additionally, we determined whether tumour mutation burden (TMB) or BRAF status were prognostic markers of survival. Low TMB rate (< 20 Mut/Mb; p = 0.0034) and BRAF p.V600 mutation (p = 0.0355) were associated with worse progression-free survival. Combining these biomarkers indicated that V600 mutant patients had significantly lower TMB (p = 0.0155). This was confirmed in the TCGA (n = 443, p = 0.0007). Integrative analysis showed germline mutation status conferred the highest risk (HR 5.2, 95% CI 1.72–15.7). Stage IV (HR 2.5, 0.74–8.6) and low TMB (HR 2.3, 0.57–9.4) were similar, whereas BRAF V600 status was the weakest prognostic biomarker (HR 1.5, 95% CI 0.44–5.2).

Abstract 3696: Determination of the expression patterns and functional implications of microRNAs in ulcerated cutaneous melanoma

Abstract Introduction: Ulcerated primary cutaneous melanomas have a poor prognosis and the underlying biology driving this aggressive behavior is largely unexplored. The presence of tumor ulceration at the time of diagnosis of cutaneous melanoma is among the top prognostic indicators for clinical outcome, associated with reduced disease free and overall survival. Thus, ulceration is employed as a clinical and histopathologic criterion for classification of melanomas into a higher tumor stage. microRNAs are small, non-coding RNAs that frequently exhibit dysregulated expression in cancer and can impact tumor biologic behavior via mediation of oncogene or tumor suppressor gene expression. While patterns of microRNA expression in melanoma have been identified that demonstrate their utility as predictive biomarkers of disease progression and metastasis, the microRNA expression profile of cutaneous melanomas with evidence of ulceration has not yet been assessed. Methods: We determined the microRNA expression profile in RNA isolated from formalin-fixed, paraffin-embedded samples of human ulcerated cutaneous melanoma relative non-ulcerated tumors (n=7 each) using the NanoString human miRNA assay platform. The impact of hsa-miR-1469, a novel microRNA demonstrating downregulated expression in ulcerated melanomas in this study, was examined using in vitro functional assays via transfection of melanoma cell lines A375, CHL-1, and MEL39 with a miR-1469 mimic construct. Results: The resultant microRNA expression data demonstrated at least 2-fold change in expression of 9 microRNAs between ulcerated and non-ulcerated melanoma tumors (p &amp;lt;0.01). Among the top differentially expressed miRs were hsa-miR-4286, hsa-miR-4488, and hsa-miR-1469, each with greater than 3.9-fold decreases in expression in the setting of ulceration relative to non-ulcerated tumors (p &amp;lt;0.0029). Restoration of miR-1469 expression resulted in significant reduction in the migration of melanoma tumor cells relative to untransfected and miR-scramble transfected controls in the CHL-1 model (0.41-fold decrease, p = 0.046 and 0.36-fold decrease, p = 0.013, respectively), with similar patterns observed in A375 and MEL39 cell lines. Transfection with a miR-1469 mimic also increased apoptosis in response to fludarabine (2.32-fold increase, p=0.044). Conclusions: The microRNA expression profile generated from this study highlights a subset of microRNAs that may impact disease progression in patients with ulcerated tumors via mediation of tumor cell functions, and provides further molecular characterization of a poorly understood clinical and histopathologic phenotype. Additional studies examining the expression and function of these microRNAs are necessary to determine their utility as predictive biomarkers and role in tumor progression in the setting of ulcerated cutaneous melanoma. Citation Format: Mallory J. DiVincenzo, Casey Ren, Lorena Suarez-Kelly, Maribelle Moufawad, Zoe Barricklow, Paolo Fadda, Lianbo Yu, John H. Howard, Alejandro A. Gru, William E. Carson. Determination of the expression patterns and functional implications of microRNAs in ulcerated cutaneous melanoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3696.

The RAC1 Target NCKAP1 Plays a Crucial Role in the Progression of Braf;Pten-Driven Melanoma in Mice

BRAFV600E is the most common driver mutation in human cutaneous melanoma and is frequently accompanied by loss of the tumor-suppressing phosphatase PTEN. Recent evidence suggests a co-operative role for RAC1 activity in BRAFV600E-driven melanoma progression and drug resistance. However, the underlying molecular mechanisms and the role of RAC1 downstream targets are not well-explored. In this study, we examine the role of the NCKAP1 subunit of the pentameric cytoskeletal SCAR/WAVE complex, a major downstream target of RAC1, in a mouse model of melanoma driven by BRAFV600E;PTEN loss. The SCAR/WAVE complex is the major driver of lamellipodia formation and cell migration downstream of RAC1 and depends on NCKAP1 for its integrity. Targeted deletion of Nckap1 in the melanocyte lineage delayed tumor onset and progression of a mutant Braf;Pten loss‒driven melanoma mouse model. Nckap1-depleted tumors displayed fibrotic stroma withincreased collagen deposition concomitant with enhanced immune infiltration. Nckap1 loss slowed proliferation and tumor growth, highlighting a role in cell-cycle progression. Altogether, we propose that NCKAP1-orchestrated actin polymerization is essential for tumor progression and maintenance of tumor tissue integrity in a mutant Braf/Pten loss‒driven mouse model for melanoma.

Guizhi Fuling pills inhibit the proliferation, migration and invasion of human cutaneous malignant melanoma cells by regulating the molecular axis of LncRNA TPT1-AS1 / miR-671-5p

The current research was aimed to explore the effects of Guizhi Fuling Pills on the proliferation, migration and invasion of human cutaneous malignant melanoma cells and its regulation on the molecular axis of LncRNA TPT1-AS1 / miR-671-5p. Human cutaneous malignant melanoma cells A375 were cultured in vitro and randomly divided into Con group, Guizhi Fuling pills-L group, Guizhi Fuling pills-M group, Guizhi Fuling pills-H group, Guizhi Fuling pills-H + pcDNA group, Guizhi Poria pills-H + pcDNA-TPT1-AS1 group. MTT was used to detect cell proliferation. The Transwell cell test was used to detect cell migration and invasion. qRT-PCR was used to detect the expression of TPT1-AS1 and miR-671-5p. The dual-luciferase report experiment verified the targeting relationship of TPT1-AS1, miR-671-5p. Western blot was used to detect the expression of Ki-67, PCNA, MMP-2 and MMP-9. Compared with Con group, Guizhi Fuling Pills could inhibit cell proliferation, migration and invasion (p&lt;0.05), and also inhibit the expression of Ki-67, PCNA, MMP-2, MMP-9, TPT1-AS1 (p&lt;0.05), promote the expression of miR-671-5p (p&lt;0.05)., and the differences between the indexes of Guizhi Fuling Pill-L group, Guizhi Fuling Pill-M group and Guizhi Fuling Pill-H group were statistically significant (p&lt;0.05). The dual-luciferase report experiment confirmed that TPT1-AS1 could target and bind to miR-671-5p and could regulate the expression and activity of miR-671-5p. Overexpression of TPT1-AS1 could reduce the inhibitory effect of Guizhi Fuling Pills on proliferation, migration and invasion of A375 cells. Guizhi Fuling Pill may reduce the proliferation, migration and invasion of human cutaneous malignant melanoma cells by down-regulating the expression of TPT1-AS1 and up-regulating the expression of miR-671-5p.

Aggressiveness Potential of Spontaneous Canine Mucosal Melanoma Can Dictate Distinct Cancer Stem Cell Compartment Behaviors in Regard to Their Initial Size and Expansion Abilities.

Mucosal melanoma represents one of the most highly metastatic and aggressive subtypes of melanoma. The biology of mucosal melanoma is poorly documented, and the lack of experimental models makes it difficult to design and test new therapies. Dogs are frequently affected by melanomas of the oral cavity, making spontaneous canine melanoma a potentially predictable model for their human counterpart. We recently established and characterized two new canine mucosal melanoma cell lines named OCR_OCMM1 and OCR_OCMM2. Here, we identified quiescent cancer stem cell (CSC) subpopulations in both canine cell lines that displayed similarities to human quiescent CSCs: canine melanoma CSCs had the ability to self-renew, produced nonstem cell (SC) progeny, and formed melanospheres that recapitulated the phenotypic profile of the parental tumor. These CSCs also formed melanoma in immunodeficient mice, and the inhibition of PI3K/AKT signaling expanded the CSC pool. A subset of non-CSCs transitioned to become CSCs. OCR_OCMM1 and OCR_OCMM2 displayed different CSC compartment behaviors in regard to their initial size and expansion abilities. Collectively, this study showed that the OCR_OCMM1 and OCR_OCMM2 canine melanoma cell lines are powerful cellular tools to study melanoma SCs, not only for mucosal but also for the more common human cutaneous melanoma.

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.

693 p38 signaling regulates human cutaneous metastatic melanoma (MM) invasion and MM-dependent disruption of keratinocyte differentiation

Advancing our understanding of MM invasion mechanisms is vital for developing new mechanism-based therapies and improving MM outcomes. Here we describe an optimized organotypic human skin equivalent co-culture system of primary epidermal keratinocytes, MM cells, and stromal fibroblasts recently developed in our laboratory in order to reliably model early invasive behavior of MM as well as melanoma-keratinocyte crosstalk in the tissue microenvironment that more accurately reflects human disease pathology. p38 kinases p38α/δ are the predominant p38 isoforms in keratinocytes, while p38α/β are the most abundant p38s in MM cells. However, the roles of p38 kinases in regulation of human cutaneous MM invasion or in control of melanoma-keratinocyte communication remain to be elucidated. Our data showed that in human skin equivalents harboring human A375 MM cells, pharmacologic inhibition of p38α/β isoforms with specific inhibitor SB203580 led to increased invasion of A375 cells into the dermis, as manifest by significantly increased size of the dermal nests of A375 cells relative to size of those in control vehicle-treated cultures. The hyper-invasive MM phenotype observed in skin equivalents treated with SB203580 was reversed by treatment with potent pan-p38 inhibitor Compound 62 back to the levels displayed by the control cultures. These data suggest that p38α/β function to restrict MM invasion, and support a role for keratinocyte p38δ in promoting MM invasion in this model system. Furthermore, reflecting effect of melanoma on keratinocyte differentiation as observed in human disease, skin equivalents harboring A375 MM cells displayed a marked disruption of keratinocyte differentiation program as evidenced by reduced cornification, absence of granular layer, and severely diminished expression of differentiation markers. Pan-p38 inhibition partially restored keratinocyte differentiation, supporting a role for p38 signaling in MM-dependent loss of the latter in this system.

Mechanisms of JAK-STAT signaling pathway mediated by CXCL8 gene silencing on epithelial-mesenchymal transition of human cutaneous melanoma cells.

Effect of CXCL8 gene silencing-mediated JAK-STAT signaling pathway on epithelial-mesenchymal transition (EMT) of human cutaneous melanoma cells was explored. Eighty patients with cutaneous melanoma were enrolled in the study. Cells were transfected accordingly and divided into five groups: The blank group (human cutaneous melanoma cells), NC group (human cutaneous melanoma cells + blank vector plasmid transfection), CXCL8 siRNA group (human cutaneous melanoma cells + CXCL8 silent expression vector plasmid transfection), AG490 group (human cutaneous melanoma cells + JAK-STAT signal pathway inhibitor transfection), CXCL8 siRNA + AG490 group (human cutaneous melanoma cells + JAK-STAT signaling pathway inhibitor + CXCL8 silent expression vector plasmid transfection). The expression levels of CXCL8, JAK2, STAT3, epithelial cadherin (E-cadherin), neurotrophic cadherin (N-cadherin) and vimentin in tissues and cells were detected by RT-qPCR and western blot analysis. CCK-8 and flow cytometry were used to detect cell proliferation and apoptosis. Compared with adjacent normal tissues, the expression of E-cadherin in human cutaneous melanoma tissues was significantly decreased, whereas the expression of CXCL8, JAK2, STAT3, vimentin and N-cadherin was significantly increased (P<0.05). Compared with the blank group, CXCL8 siRNA group and CXCL8 siRNA + AG490 group had significantly lower expression of CXCL8 (P<0.05). Compared with the blank group, the expression levels of JAK2, STAT3, vimentin and N-cadherin in CXCL8 siRNA group, AG490 group and CXCL8 siRNA + AG490 group were decreased, the expression of E-cadherin was increased, the cell proliferation ability was decreased and apoptosis was increased (P<0.05). Compared with CXCL8 siRNA group, the expression of JAK2, STAT3, vimentin and N-cadherin in CXCL8 siRNA + AG490 group were significantly decreased, the expression of E-cadherin was significantly increased, cell proliferation ability was decreased and apoptosis was increased (P<0.05). In conclusion, CXCL8 gene expression silencing may inhibit EMT and cell proliferation while promoting cell apoptosis of human cutaneous melanoma cells by inhibiting the activation of JAK-STAT signaling pathway.

Vascular endothelial growth factor/semaphorin-3A ratio and SEMA3A expression in cutaneous malignant melanoma.

Breslow thickness and Clark level are still important factors for cutaneous melanoma, but do not provide a precise prognosis in all cases. It is necessary to find new factors capable of a more accurate prediction of the tumor course. Angiogenesis is essential for tumor development and progression and is regulated by vascular endothelial growth factor A (VEGF-A) and semaphorins (SEMA), in particular, SEMA3A inhibits angiogenesis by affecting VEGF signaling. However, the prognostic role of angiogenetic factors remains unclear. To date, no information is available on SEMA3A in human melanoma. Microvessel density, immunohistochemical and mRNA VEGF and SEMA3A expression level in 60 thin (Breslow thickness ≤ 1.0 mm), 60 intermediate (1.1-4.0 mm) and 50 thick (>4.0 mm) primary human cutaneous melanomas were investigated and related to clinical/pathological parameters and disease-specific survival. No positive association between Breslow thickness, Clark level, metastasis presence and survival was identified; Clark level was poorly related to survival. VEGF and microvessel density were significantly higher in intermediate and thick melanomas and related to Breslow thickness and Clark level but not to metastasis status and survival. On the contrary, SEMA3A was significantly reduced in intermediate and thick melanomas and associated to metastasis and poor survival. VEGF/SEMA3A ratio was higher in the worst prognosis, resulting the most closely related factor with metastasis and survival. SEMA3A expression and VEGF/SEMA3A ratio turned out to be valuable prognostic biomarkers in patients affected by cutaneous melanoma, in particular with Breslow thickness >1 mm. SEMA3A might serve as a candidate tumor suppressor in cutaneous melanoma therapy.

Human Plasmacytoid Dendritic Cells and Cutaneous Melanoma.

The prognosis of metastatic melanoma (MM) patients has remained poor for a long time. However, the recent introduction of effective target therapies (BRAF and MEK inhibitors for BRAFV600-mutated MM) and immunotherapies (anti-CTLA-4 and anti-PD-1) has significantly improved the survival of MM patients. Notably, all these responses are highly dependent on the fitness of the host immune system, including the innate compartment. Among immune cells involved in cancer immunity, properly activated plasmacytoid dendritic cells (pDCs) exert an important role, bridging the innate and adaptive immune responses and directly eliminating cancer cells. A distinctive feature of pDCs is the production of high amount of type I Interferon (I-IFN), through the Toll-like receptor (TLR) 7 and 9 signaling pathway activation. However, published data indicate that melanoma-associated escape mechanisms are in place to hijack pDC functions. We have recently reported that pDC recruitment is recurrent in the early phases of melanoma, but the entire pDC compartment collapses over melanoma progression. Here, we summarize recent advances on pDC biology and function within the context of melanoma immunity.

Tumor-Derived Lactic Acid Contributes to the Paucity of Intratumoral ILC2s

Group 2 innate lymphoid cells (ILC2s) are abundant in non-lymphoid tissues and increase following infectious and inflammatory insults. In solid tumors, however, ILC2s constitute a relatively small proportion of immune cells. Here, we show, using melanoma as a model, that while the IL-33/IL C2/eosinophil axis suppresses tumor growth, tumor-derived lactate attenuates the function and survival of ILC2s. Melanomas with reduced lactate production (LDHAlow) are growth delayed and typified by an increased number of ILC2s compared with control tumors. Upon IL-33 stimulation, ILC2s accompanied by eosinophils more effectively restrain the growth of LDHAlow tumors than control melanomas. Furthermore, database analysis reveals a negative correlation between the expression of LDHA and markers associated with ILC2s and the association of high expression of IL33 and an eosinophil marker SIGLEC8 with better overall survival in human cutaneous melanoma patients. This work demonstrates that the balance between the IL-33/ILC2/eosinophil axis and lactate production by tumor cells regulates melanoma growth.

Cancer stem cells, plasticity, and drug resistance.

Melanoma is a highly aggressive tumor and almost always fatal when metastatic. Herein, we discuss recent findings on the mechanisms of resistance of human cutaneous melanoma. To achieve a precision medicine approach, the heterogeneity and plasticity of tumor cells are two crucial aspects to be investigated in depth. In fact, to understand the mechanisms that cells use to acquire a resistant phenotype after chemotherapy or how resistant cells inside the tumor are selected, it is the most important issue for a successful therapy. Since new therapeutic strategies are trying to go in this direction, we discuss here the state of the art of the research and the clinical impact of these strategies. We also discuss and suggest future research directions to develop approaches able to define the best concentration and time of exposure of the drug or the cocktails of drugs for each specific patient based on his/her biological features.

GLT8D1 overexpression as a novel prognostic biomarker in human cutaneous melanoma

Aberrant glycosylation plays a major role in the progression of melanoma, but little is known about glycosyltransferases. Glycosyltransferase 8 domain containing 1 (GLT8D1) is located in the Golgi apparatus and is related to transferase activity in mammals. However, its role in cancer remains unclear. The aim of this study was to investigate the expression of GLT8D1 in human melanoma and explore the relationship between GLT8D1 expression and the clinicopathological characteristics of melanoma patients via GEO data analysis combined with clinical patient data. The analysis of 45 malignant melanoma samples and 18 benign nevus samples from the GEO database was performed. Moreover, 67 patients with cutaneous melanoma and 38 patients with mucosal melanoma as well as 40 benign nevus samples were collected for our study. Immunohistochemistry analyses were implemented to evaluate GLT8D1 expression at protein level. The GEO data analysis exhibited that the GLT8D1 mRNA expression was upregulated in the melanoma samples compared with the benign nevus samples. Likewise, GLT8D1 protein expression in the cutaneous melanoma and mucosal melanoma samples was significantly higher than that in the benign nevus tissue samples (P = 0.001 and 0.046, respectively). Furthermore, the GLT8D1 protein expression in cutaneous melanoma was higher than that in mucosal melanoma (P = 0.001). The high GLT8D1 protein expression was remarkably correlated with Clark level (P = 0.027), AJCC stage (P = 0.003), ulceration status (P = 0.041), Ki-67 expression (P = 0.030) and especially with histopathological type (P = 0.001). The results of the Kaplan-Meier survival and Cox regression analyses revealed that cutaneous melanoma patients with high GLT8D1 expression (P = 0.036), Clark level (P = 0.018) and advanced AJCC stage (P = 0.003) encountered poor overall survival. Overall survival (P = 0.040) and progression-free survival (P = 0.019) were worse for the patients with high GLT8D1 expression than for the patients with low expression. These data implied that GLT8D1 could be an independent prognostic factor for an unfavorable prognosis in cutaneous malignant melanoma patients and that GLT8D1 overexpression might serve as a novel prognostic biomarker.

E2F1/IGF-1R Loop Contributes to BRAF Inhibitor Resistance in Melanoma

E2F1/IGF-1R Loop Contributes to BRAF Inhibitor Resistance in Melanoma

RETRACTED ARTICLE: Overexpressed VEPH1 inhibits epithelial-mesenchymal transition, invasion, and migration of human cutaneous melanoma cells through inactivating the TGF-β signaling pathway

Statement of Retraction We, the Editors and Publisher of the journal Cell Cycle, have retracted the following article: Hao Feng, Xiao-Min Jia, Ni-Na Gao, Hua Tang, Wei Huang, and Ning Ning. Overexpressed VEPH1 inhibits epithelial-mesenchymal transition, invasion, and migration of human cutaneous melanoma cells through inactivating the TGF-β signaling pathway. Cell Cycle. 2019;18(21):2860-2875. doi: 10.1080/15384101.2019.1638191. Since publication, concerns have been raised about the integrity of the data in the article. When approached for an explanation, the authors have been unable to address all the concerns raised and have not been able to provide all their original data. As verifying the validity of published work is core to the integrity of the scholarly record, we are therefore retracting the article. The corresponding author listed in this publication has been informed. We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

Blockade of Lymphangiogenesis Shapes Tumor-Promoting Adipose Tissue Inflammation

Tumor-associated lymphangiogenesis correlates with lymph node metastasis and poor outcome in several human malignancies. In addition, the presence of functional lymphatic vessels regulates the formation of tumor inflammatory and immune microenvironments. Although lymphatic structures are often found deeply integrated into the fabric of adipose tissue, the impact of lymphangiogenesis on tumor-associated adipose tissue (AT) has not yet been investigated. Using K14-VEGFR3-Ig mice that constitutively express soluble vascular endothelial growth factor receptor (VEGFR) 3-Ig in the skin, scavenging VEGF-C and VEGF-D, the role of lymphangiogenesis in the generation of an inflammatory response within tumor-associated AT was studied. Macrophages expressing lymphatic vessel endothelial hyaluronan receptor-1 were found within peritumoral adipose tissue from melanoma-bearing K14-VEGFR3-Ig mice, which were further enriched with alternatively activated macrophages based on surface marker CD301/C-type lectin domain family 10 member A expression. The blockade of lymphangiogenesis also resulted in accumulation of the cytokine IL-6, which correlated with enhanced macrophage proliferation of the alternatively activated phenotype. Furthermore, melanomas co-implanted with freshly isolated adipose tissue macrophages grew more robustly than melanomas growing alone. In human cutaneous melanomas, adipocyte-selective FABP4 transcripts closely correlated with gene signatures of CLEC10A and were associated with poor overall survival. These data suggest that the blockade of pathways regulating lymphatic vessel formation shapes an inflammatory response within tumor-associated AT by facilitating accumulation of tumor-promoting alternatively activated macrophages.