MMP2 expression is a prognostic marker for primary melanoma patients

Functional relevance of MMP2 promoter variants in gallbladder cancer: A case-control study in an Eastern Indian Population

Gallbladder cancer (GBC) is a prevalent and deadly form of bile duct cancer, associated with poor prognosis. This study aimed to investigate the genetic factors contributing to the high incidence of GBC in certain geographical regions, particularly in the Northern and Eastern parts of India. The present case-control study focused on MMP2, a gene involved in tumor progression and metastasis, as a potential candidate in GBC pathogenesis. We scanned MMP2 promoter for twelve SNPs using Sanger's sequencing and carried out a case-control study in 300 cases and 300 control samples. We found five rare variants (rs1961998763, rs1961996235, rs1391392808, rs1488656253, and rs17859816) and one nonpolymorphic SNP (rs17859817). Our results revealed a significant association between GBC and MMP2 promoter SNPs, rs243865 (Allelic-Padjusted = 0.0353) and g.55477735G > A (Allelic-Padjusted = 9.22E-05). Moreover, the haplotype "C-C-A-C-C" exhibited a significant association with GBC (P = 4.23E-05). Genotype-phenotype correlation for variant rs243865, in the GBC patient tissue samples, established that 'T' risk allele carriers had higher expression levels of MMP2. Additionally, luciferase reporter assay in HEK293T cells revealed the probable regulatory role of rs243865 variant allele 'T' in MMP2 expression. Our study uncovers the association of MMP2 promoter SNPs with GBC and their role in regulating its expression.

Generation of 3D melanoma models using an assembloid-based approach

While 3D tumor models have greatly evolved over the past years, there is still a strong requirement for more biosimilar models which are capable of recapitulating cellular crosstalk within the tumor microenvironment while equally displaying representative levels of tumor aggressiveness and invasion. Herein, we disclose an assembloid melanoma model based on the fusion of individual stromal multicellular spheroids (MCSs). In contrast to more traditional tumor models, we show that it is possible to develop self-organizing, heterotypic melanoma models where tumor cells present stem-cell like features like up-regulated pluripotency master regulators SOX2, POU5F1 and NANOG. Additionally, these assembloids display high levels of invasiveness while embedded in 3D matrices as evidenced by stromal cell promotion of melanoma cell invasion via metalloproteinase production. Furthermore, sensitivity to anticancer drug doxorubicin was demonstrated for the melanoma assembloid model. These findings suggest that melanoma assembloids may play a significant role in the field of 3D cancer models as they more closely mimic the tumor microenvironment when compared to more traditional MCSs, opening the doors to a better understanding of the role of tumor microenvironment in supporting tumor progression. STATEMENT OF SIGNIFICANCE: The development of complex 3D tumor models that better recapitulate the tumor microenvironment is crucial for both an improved comprehension of intercellular crosstalk and for more efficient drug screening. We have herein developed a self-organizing heterotypic assembloid-based melanoma model capable of closely mimicking the tumor microenvironment. Key features recapitulated were the preservation of cancer cell stemness, sensitivity to anti-cancer agents and tumor cell invasion promoted by stromal cells. The approach of pre-establishing distinct stromal domains for subsequent combination into more complex tumor constructs provides a route for developing superior tumor models with a higher degree of similarity to native cancer tissues.

Exogenous recombinant N-acetylgalactosamine-4-sulfatase (Arylsulfatase B; ARSB) inhibits progression of B16F10 cutaneous melanomas and modulates cell signaling

In the syngeneic, subcutaneous B16F10 mouse model of malignant melanoma, treatment with exogenous ARSB markedly reduced tumor size and extended survival. In vivo experiments showed that local treatment with exogenous N-acetylgalactosamine-4-sulfatase (Arylsulfatase B; ARSB) led to reduced tumor growth over time (p < 0.0001) and improved the probability of survival up to 21 days (p = 0.0391). Tumor tissue from the treated mice had lower chondroitin 4-sulfate (C4S) content and lower sulfotransferase activity. The free galectin-3 declined, and the SHP2 activity increased, due to altered binding with chondroitin 4-sulfate. These changes induced effects on transcription, which were mediated by Sp1, phospho-ERK1/2, and phospho-p38 MAPK. Reduced mRNA expression of chondroitin sulfate proteoglycan 4 (CSPG4), carbohydrate sulfotransferase 15 (N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase), and matrix metalloproteinases 2 and 9 resulted. Experiments in the human melanoma cell line A375 demonstrated similar responses to exogenous ARSB as in the tumors, and inverse effects followed ARSB siRNA. ARSB, which removes the 4-sulfate group at the non-reducing end of C4S, acts as a tumor suppressor, and treatment with exogenous ARSB impacts on vital cell signaling and reduces the expression of critical genes associated with melanoma progression.

Downregulated BIRC5 inhibits proliferation and metastasis of melanoma through the β-catenin/HIF-1α/VEGF/MMPs pathway

PURPOSE

Melanoma is a malignant skin tumor caused by melanocytes and associated with high mortality rates. This study aims to investigate the specific mechanism of ZWZ-3 in melanoma proliferation and metastasis.

METHODS

RNA sequencing was performed to identify the effect of ZWZ-3 on gene expression. siRNA was used to inhibit BIRC5 gene expression in the B16F10 cell line. A zebrafish tumor model was used to assess the therapeutic effect of ZWZ-3 in vivo. Mechanistic insights into the inhibition of tumor metastasis by ZWZ-3 were obtained through analysis of tumor tissue sections in mice.

RESULTS

Our findings demonstrated that ZWZ-3 suppressed melanoma cell proliferation and migration. We performed RNA sequencing in melanoma cells after the treatment with ZWZ-3 and found that Birc5, which is closely associated with tumor metastasis, was significantly down-regulated. Bioinformatics analysis and the immuno-histochemical results of tissue chips for melanoma further confirmed the high expression of BIRC5 in melanoma and its effect on disease progression. Moreover, Birc5 knock-down significantly inhibited melanoma cell proliferation and metastasis, which was correlated with the β-catenin/HIF-1α/VEGF/MMPs pathway. Additionally, ZWZ-3 significantly inhibited tumor growth in the zebrafish tumor model without any evident side effects. Histological and immuno-histochemical analyses revealed that ZWZ-3 inhibited tumor cell metastasis by down-regulating HIF-1α, VEGF, and MMP9.

CONCLUSION

Our findings revealed that ZWZ-3 could downregulate BIRC5 and inhibit melanoma proliferation and metastasis through the β-catenin/HIF-1α/VEGF/MMPs pathway. Therefore, BIRC5 represents a promising therapeutic target for the treatment of melanoma.

Knockdown of FGFR3 inhibits the proliferation, migration and invasion of intrahepatic cholangiocarcinoma

The FGF/FGFR signaling axis deregulation of the fibroblast growth factor receptor (FGFR) family is closely related to tumorigenesis, tumor progression and drug resistance to anticancer therapy. And fibroblast growth factor receptor 3 (FGFR3) is one member of this family. In this study, we aimed to investigate the effect of siRNA-induced knockdown of FGFR3 on the biological behaviors of intrahepatic cholangiocarcinoma (ICC). The expression levels of FGFR3 were determined in three intrahepatic cholangiocarcinoma cell lines RBE, HUCCT1 and HCCC9810 cell lines by Western blot. FGFR3 expression in RBE cell line was knocked down by siRNA. Our study found that knockdown of FGFR3 inhibited the migration, invasion and proliferation of ICC cells using Wound healing assay, Transwell migration and invasion assays and Cell proliferation assay. And significantly down-regulated the protein expression levels of MMP2, cyclinD1, and NCadherin, but had no significant effect on MMP9, cyclinD3, vimentin, E-cadherin protein. In addition, we found that ERK/c-Myc presumably is its signaling pathway by bioinformatics analysis and Western blot verification. To sum up, knockdown of FGFR3 inhibited the migration, invasion and proliferation of ICC cells. It demonstrated that FGFR3 probably becomes a therapeutic target for ICC and increases the proportion of potentially curable intrahepatic cholangiocarcinoma patients treated with FGFR inhibitors.

MMP2 is a immunotherapy related biomarker and correlated with cancer-associated fibroblasts infiltrate in melanoma

BACKGROUND

Mounting evidence supports that matrix metalloproteinase (MMPs) are highly associated with tumor progression and that targeting MMPs may overcome the barrier of immune suppression. Among these, whether MMP2 functions as an immunosuppressive role in melanoma, remains unclear.

METHODS

The Cancer Genome Atlas (TCGA) and Gene Expression Profiling Interactive Analysis 2 (GEPIA2) databases were used to assess the prognosis of MMP2 in melanoma, after which Tumor immune estimation resource (TIMER) was used to explore the relationship between MMP2 expression and cancer associated fibroblasts (CAFs) infiltration. Finally, we evaluated the efficacy of MMP2 inhibitor on CAFs infiltration and immunotherapy using a mouse melanoma model.

RESULTS

In general, the expression of MMP2, MMP13, MMP16, MMP17 and MMP25 were significantly associated with skin cutaneous melanoma (SKCM) patients prognosis, among which MMP2 low expression benefited patients the most. Especially, the overall survival (OS) of BRAF mutation patients with high MMP2 expression was significantly lower than the MMP2 low expression group, but there was no significant difference in BRAF wild-type patients. KEGG and GO enrichment analysis indicated that MMP2 related genes were mostly associated with extracellular structure organization, collagen-containing extracellular matrix and extracellular matrix structural constituent. Furthermore, in almost all cancers, MMP2 expression was positively correlated with CAFs infiltration. MMP2 inhibitor works synergistically with PD-1 antibody and induces tumor regression in a mouse melanoma model, which is dependent on decreased CAFs infiltration.

CONCLUSIONS

This suggests that MMP2 plays a vital role in the regulation of CAFs infiltration, potentially participating in immunotherapy response, and thus representing a valuable target of immunotherapy in melanoma.

Bioinformatics evaluation of anticancer properties of GP63 protein-derived peptides on MMP2 protein of melanoma cancer

Background

GP63, also known as Leishmanolysin, is a multifunctional virulence factor abundant on the surface of Leishmania spp. small peptides with anticancer capabilities that are selective and toxic to cancer cells are known as anticancer peptides. We aimed to demonstrate the activity of GP63 and its anticancer properties on melanoma using a range of in silico tools and screening methods to identify predicted and designed anticancer peptides.

Methods

Various in silico modeling methodologies are used to establish the three-dimensional (3D) structure of GP63. Refinement and re-evaluation of the modeled structures and the built models' quality evaluated using the different docking used to find the interacting amino acids between MMP2 and GP63 and its anticancer peptides. AntiCP2.0 is used for screening anticancer peptides. 2D interaction plots of protein-ligand complexes evaluated by Protein-Ligand Interaction Profiler server. It is for the first time that used anticancer peptides of GP63 and the predicted and designed peptides.

Results

We used 3 peptides of GP63 based on the AntiCP 2.0 server with scores of 0.63, 0.53, and 0.49, and common peptides of GP63/MMP2 (continues peptide: mean the completely selected peptide after docking with non-anticancer effect, predicted with 0.58 score and designed peptides with 0.47 and 0.45 scores by AntiCP 2.0 server).

Conclusions

The antileishmanial and anticancer peptide research topics exemplify the multidisciplinary nature of peptide research. The advancement of therapeutics targeting cancer and/or Leishmania requires an interconnected research strategy shown in this work.

Circ_0084043-miR-134-5p axis regulates PCDH9 to suppress melanoma

The low survival rates, poor responses, and drug resistance of patients with melanoma make it urgent to find new therapeutic targets. This study investigated whether the circ_0084043-miR-134-5p axis regulates the antitumor effect of protocadherin 9 (PCDH9) in melanoma. Ectopic expression or knock down (KD) of PCDH9 with a lentivirus vector, we explored its effects on the proliferation, invasion, and apoptosis of melanoma and verified its regulatory effect on ras-related C3 botulinum toxin substrate 1 (RAC1), proline-rich tyrosine kinase 2 (Pyk2), Cyclin D1, matrix metalloproteinase 2 (MMP2), and MMP9. We further observed the effect of KD circ_0084043 on the malignant behavior of melanoma and studied whether circ_0084043 sponged miR-134-5p and regulated PCDH9. We found that circ_0084043 was overexpressed in melanoma and associated with the malignant phenotype. PCDH9 was poorly expressed in human melanoma tissues, and overexpression of PCDH9 inhibited melanoma progression. Quantitative real-time PCR and Western blotting results showed that overexpression of PCDH9 could downregulate RAC1, MMP2, and MMP9 and upregulate Pyk2 and Cyclin D1. Circ_0084043 KD inhibited invasion and promoted apoptosis in melanoma cells. Circ_0084043 could sponge miR-134-5p and thus indirectly regulate PCDH9. Furthermore, we discovered that inhibiting circ_0084043 had an anti–PD-Ll effect. In vivo, PCDH9 overexpression inhibited melanoma tumor growth, but PCDH9 KD promoted it. In conclusion, PCDH9, which is regulated by the circ 0084043-miR-134-5p axis, can suppress malignant biological behavior in melanoma and influence the expression levels of Pyk2, RAC1, Cyclin D1, MMP2, and MMP9.

Melanoma Mediated Disruption of Brain Endothelial Barrier Integrity Is Not Prevented by the Inhibition of Matrix Metalloproteinases and Proteases

We have previously shown that human melanoma cells rapidly decrease human brain endothelial barrier strength. Our findings showed a fast mechanism of melanoma mediated barrier disruption, which was localised to the paracellular junctions of the brain endothelial cells. Melanoma cells are known to release molecules which cleave the surrounding matrix and allow traversal within and out of their metastatic niche. Enzymatic families, such as matrix metalloproteinases (MMPs) and proteases are heavily implicated in this process and their complex nature in vivo makes them an intriguing family to assess in melanoma metastasis. Herein, we assessed the expression of MMPs and other proteases in melanoma conditioned media. Our results showed evidence of a high expression of MMP-2, but not MMP-1, -3 or -9. Other proteases including Cathepsins D and B were also detected. Recombinant MMP-2 was added to the apical face of brain endothelial cells (hCMVECs), to measure the change in barrier integrity using biosensor technology. Surprisingly, this showed no decrease in barrier strength. The addition of potent MMP inhibitors (batimastat, marimastat, ONO4817) and other protease inhibitors (such as aprotinin, Pefabloc SC and bestatin) to the brain endothelial cells, in the presence of various melanoma lines, showed no reduction in the melanoma mediated barrier disruption. The inhibitors batimastat, Pefabloc SC, antipain and bestatin alone decreased the barrier strength. These results suggest that although some MMPs and proteases are released by melanoma cells, there is no direct evidence that they are substantially involved in the initial melanoma-mediated disruption of the brain endothelium.

The Role of Extracellular Matrix Remodeling in Skin Tumor Progression and Therapeutic Resistance

The extracellular matrix remodeling in the skin results from a delicate balance of synthesis and degradation of matrix components, ensuring tissue homeostasis. These processes are altered during tumor invasion and growth, generating a microenvironment that supports growth, invasion, and metastasis. Apart from the cellular component, the tumor microenvironment is rich in extracellular matrix components and bound factors that provide structure and signals to the tumor and stromal cells. The continuous remodeling in the tissue compartment sustains the developing tumor during the various phases providing matrices and proteolytic enzymes. These are produced by cancer cells and stromal fibroblasts. In addition to fostering tumor growth, the expression of specific extracellular matrix proteins and proteinases supports tumor invasion after the initial therapeutic response. Lately, the expression and structural modification of matrices were also associated with therapeutic resistance. This review will focus on the significant alterations in the extracellular matrix components and the function of metalloproteinases that influence skin cancer progression and support the acquisition of therapeutic resistance.

Deciphering the Underlying Mechanisms of Formula Le-Cao-Shi Against Liver Injuries by Integrating Network Pharmacology, Metabonomics, and Experimental Validation

Le-Cao-Shi (LCS) has long been used as a folk traditional Chinese medicine formula against liver injuries, whereas its pharmacological mechanisms remain elusive. Our study aims to investigate the underlying mechanism of LCS in treating liver injuries via integrated network pharmacology, metabonomics, and experimental validation. By network pharmacology, 57 compounds were screened as candidate compounds based on ADME parameters from the LCS compound bank (213 compounds collected from the literature of three single herbs). According to online compound–target databases, the aforementioned candidate compounds were predicted to target 87 potential targets related to liver injuries. More than 15 pathways connected with these potential targets were considered vital pathways in collectively modulating liver injuries, which were found to be relevant to cancer, xenobiotic metabolism by cytochrome P450 enzymes, bile secretion, inflammation, and antioxidation. Metabonomics analysis by using the supernatant of the rat liver homogenate with UPLC-Q-TOF/MS demonstrated that 18 potential biomarkers could be regulated by LCS, which was closely related to linoleic acid metabolism, glutathione metabolism, cysteine and methionine metabolism, and glycerophospholipid metabolism pathways. Linoleic acid metabolism and glutathione metabolism pathways were two key common pathways in both network pharmacology and metabonomics analysis. In ELISA experiments with the CCl₄-induced rat liver injury model, LCS was found to significantly reduce the levels of inflammatory parameters, decrease liver malondialdehyde (MDA) levels, and enhance the activities of hepatic antioxidant enzymes, which validated that LCS could inhibit liver injuries through anti-inflammatory property and by suppressing lipid peroxidation and improving the antioxidant defense system. Our work could provide new insights into the underlying pharmacological mechanisms of LCS against liver injuries, which is beneficial for its further investigation and modernization.

Biosensors for Caspase-3: From chemical methodologies to biomedical applications

Caspase-3 plays irreplaceable roles in apoptosis and related diseases. An imbalance in the measured levels of Caspase-3 is implicated in irreversible apoptosis. Therefore, the detection of Caspase-3 is of great significance for apoptosis imaging and the evaluation effect of early tumor treatment and other diseases. Herein, advances in the recent innovations of Caspase-3 response fluorescence biosensors, including molecular probes and nanoprobes, are systematically summarized in sections corresponding. The performances of various luminescence probes in Caspase-3 detection are discussed intensively in the design strategy of chemical structure, response mechanism and biological application. Finally, the current challenges and prospects of the design of new Caspase-3 responsive fluorescence probes for apoptosis imaging, or similar molecular event are proposed.

C-phycocyanin decreases proliferation and migration of melanoma cells: In silico and in vitro evidences

The incidence and number of deaths caused by melanoma have been increasing in recent years, and the pigment C-phycocyanin (C-PC) appears as a possible alternative to treat this disease. So, the objective of this study was to combine in silico and in vitro analysis to understand the main anti-melanoma pathways exerted by C-PC. We evaluated the ability of C-PC to bind to the main cellular targets related in the progression of melanoma through molecular docking, and the reflection of this bind in the biological effects in the B16F10 cell line through in vitro analysis. Our results showed that C-PC was able to bind BRAF and MEK, which are related to the signal transduction pathway for proliferation and survival. There was also an interaction between C-PC and cyclin-dependent kinase 4 and 6. In vitro analysis demonstrated that C-PC decreased B16F10 cell proliferation, as observed by cell viability and mitotic index assays. C-PC also interacted with matrix metalloproteinase 2 and 9 and N-cadherin, which may have caused the decrease in cell migration observed in vitro. Besides that, C-PC interacts with VEGF, a factor responsible for regulating the proliferation and cellular invasion pathways. Finally, C-PC did not alter the cell viability of the non-tumoral melanocytes. Therefore, C-PC is a strong anti-tumor candidate for the treatment of melanoma, since it acts in different cellular pathways of melanoma, without causing damage to non-tumoral cells.

Mapping of MeLiM melanoma combining ICP-MS and MALDI-MSI methods

Here we developed a powerful tool for comprehensive data collection and mapping of molecular and elemental signatures in the Melanoma-bearing Libechov Minipig (MeLiM) model. The combination of different mass spectrometric methods allowed for detail investigation of specific melanoma markers and elements and their spatial distribution in tissue sections. MALDI-MSI combined with HPLC-MS/MS analyses resulted in identification of seven specific proteins, S100A12, CD163, MMP-2, galectin-1, tenascin, resistin and PCNA that were presented in the melanoma signatures. Furthermore, the ICP-MS method allowed for spatial detection of zinc, calcium, copper, and iron elements linked with the allocation of the specific binding proteins.

Role of Biomarkers in the Integrated Management of Melanoma

Melanoma, which is an aggressive skin cancer, is currently the fifth and seventh most common cancer in men and women, respectively. The American Cancer Society reported that approximately 106,110 new cases of melanoma were diagnosed in the United States in 2021, with 7,180 people dying from the disease. This information could facilitate the early detection of possible metastatic lesions and the development of novel therapeutic techniques for melanoma. Additionally, early detection of malignant melanoma remains an objective of melanoma research. Recently, melanoma treatment has substantially improved, given the availability of targeted treatments and immunotherapy. These developments have highlighted the significance of identifying biomarkers for prognosis and predicting therapy response. Biomarkers included tissue protein expression, circulating DNA detection, and genetic alterations in cancer cells. Improved diagnostic and prognostic biomarkers are becoming increasingly relevant in melanoma treatment, with the development of newer and more targeted treatments. Here, the author discusses the aspects of biomarkers in the real-time management of patients with melanoma.

Autophagy inhibition mediated by MCOLN1/TRPML1 suppresses cancer metastasis via regulating a ROS-driven TP53/p53 pathway

Compelling evidence has demonstrated that macroautophagy/autophagy plays an important role in regulating multiple steps of metastatic cascades; however, the precise role of autophagy in metastasis remains unclear. This study demonstrates that autophagy inhibition induced by MCOLN1/TRPML1 suppresses cancer metastasis by evoking the ROS-mediated TP53/p53 pathway. First, we found that MCOLN1-mediated autophagy inhibition not only profoundly inhibits both migration and invasion in malignant melanoma and glioma cell lines in vitro, but also suppresses melanoma metastasis in vivo. Second, our study reveals that autophagy inhibition induced by MCOLN1 leads to damaged mitochondria accumulation followed by large quantities of ROS release. Third, we demonstrate that the elevated ROS resulting from autophagy inhibition subsequently triggers TP53 activity, which in turn modulates expression of its downstream targets which are involved in a broad spectrum of the metastatic cascade to suppress metastasis including MMP members and TWIST. In summary, our findings have established a mechanism by which autophagy inhibition suppresses metastasis via the ROS-TP53 signaling pathway. More importantly, our study demonstrates that autophagy inhibition through stimulation of MCOLN1 could evidently be one of the therapeutic potentials for combating cancer metastasis.Abbreviations: 3-MA: 3-methyladenine; AA: amino acid; ATG5: autophagy related 5; ATG12: autophagy related 12; Baf-A1: bafilomycin A₁; CCCP: carbonyl cyanide m-chlorophenylhydrazone; CQ: chloroquine; DMEM: Dulbecco's Modified Eagle Medium; EMT: epithelial-mesenchymal transition; FBS: fetal bovine serum; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; HEK: human embryonic kidney; LAMP1: lysosomal associated membrane protein 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MCOLN1/TRPML1: mucolipin TRP cation channel 1; MMP: matrix metallopeptidase; NC: negative control; NRK: normal rat kidney; PBS: phosphate-buffered saline; shRNA: short hairpin RNA; siRNA: short interfering RNA; SQSTM1/p62: sequestosome 1; ULK1: unc-51 like autophagy activating kinase 1.

Dihydrocapsaicin Inhibits Cell Proliferation and Metastasis in Melanoma via Down-regulating β-Catenin Pathway

Dihydrocapsaicin (DHC) is one of the main components of capsaicinoids in Capsicum. It has been reported that DHC exerts anti-cancer effects on diverse malignant tumors, such as colorectal cancer, breast cancer, and glioma. However, studies focused on the effect of DHC upon melanoma have rarely been done. In the present study, melanoma A375 and MV3 cell lines were treated with DHC and the cell proliferation, migration, and invasion were significantly suppressed. Furthermore, DHC effectively inhibited xenograft tumor growth and pulmonary metastasis of melanoma cells in NOD/SCID mice model. It was identified that β-catenin, which plays significant roles in cell proliferation and epithelial-mesenchymal transition, was down-regulated after DHC treatment. In addition, cyclin D1, c-Myc, MMP2, and MMP7, which are critical in diverse cellular process regulation as downstream proteins of β-catenin, were all decreased. Mechanistically, DHC accelerates ubiquitination of β-catenin and up-regulates the beta-transducin repeat containing E3 ubiquitin protein ligase (BTRC) in melanoma cells. The DHC induced suppression of cell proliferation, migration, and invasion were partly rescued by exogenous β-catenin overexpression, both in vitro and in vivo. Taken together, DHC may serve as a candidate natural compound for human melanoma treatment through β-catenin pathway.

A Framework of Major Tumor-Promoting Signal Transduction Pathways Implicated in Melanoma-Fibroblast Dialogue

Simple Summary

Melanoma cells reside in a complex stromal microenvironment, which is a critical component of disease onset and progression. Mesenchymal or fibroblastic cell type are the most abundant cellular element of tumor stroma. Factors secreted by melanoma cells can activate non-malignant associated fibroblasts to become melanoma associate fibroblasts (MAFs). MAFs promote tumorigenic features by remodeling the extracellular matrix, supporting tumor cells proliferation, neo-angiogenesis and drug resistance. Additionally, environmental factors may contribute to the acquisition of pro-tumorigenic phenotype of fibroblasts. Overall, in melanoma, perturbed tissue homeostasis contributes to modulation of major oncogenic intracellular signaling pathways not only in tumor cells but also in neighboring cells. Thus, targeted molecular therapies need to be considered from the reciprocal point of view of melanoma and stromal cells.

Abstract

The development of a modified stromal microenvironment in response to neoplastic onset is a common feature of many tumors including cutaneous melanoma. At all stages, melanoma cells are embedded in a complex tissue composed by extracellular matrix components and several different cell populations. Thus, melanomagenesis is not only driven by malignant melanocytes, but also by the altered communication between melanocytes and non-malignant cell populations, including fibroblasts, endothelial and immune cells. In particular, cancer-associated fibroblasts (CAFs), also referred as melanoma-associated fibroblasts (MAFs) in the case of melanoma, are the most abundant stromal cells and play a significant contextual role in melanoma initiation, progression and metastasis. As a result of dynamic intercellular molecular dialogue between tumor and the stroma, non-neoplastic cells gain specific phenotypes and functions that are pro-tumorigenic. Targeting MAFs is thus considered a promising avenue to improve melanoma therapy. Growing evidence demonstrates that aberrant regulation of oncogenic signaling is not restricted to transformed cells but also occurs in MAFs. However, in some cases, signaling pathways present opposite regulation in melanoma and surrounding area, suggesting that therapeutic strategies need to carefully consider the tumor–stroma equilibrium. In this novel review, we analyze four major signaling pathways implicated in melanomagenesis, TGF-β, MAPK, Wnt/β-catenin and Hyppo signaling, from the complementary point of view of tumor cells and the microenvironment.

A self-designed CpG ODN enhanced the anti-melanoma effect of pimozide

Melanomas represent the deadliest form of skin cancers. Due to the intricacy of tumorigenesis, it is emergent to find effective therapies for melanomas. Researches have proved that pimozide inhibits the growth of melanoma, but the limited curing effect needs to be further improved. Nowadays, tumor immunotherapy has been widely recognized as the sole therapy that can eradicate cancers. Cytosine-phosphate-guanine oligodeoxynucleotide (CpG ODN), TLR9 receptor agonist, can significantly enhance anti-tumor immune responses. This study explored the therapeutic effect of pimozide combined with CpG ODN on melanoma-bearing mice. The results showed that pimozide combined with CpG ODN effectively inhibited the growth of melanoma and prolonged the survival of melanoma-bearing mice, inhibited the expression of MMP2 and p-Stat5, increased the infiltration of CD4⁺ and CD8⁺ T cells in tumor, raised the ratios of CD4⁺, CD8⁺ T cells and NK cells. These all indicated that the combination treatment improved the anti-tumor effect of pimozide on mice. The anti-tumor mechanism might be attributed to cell apoptosis induction, invasion inhibition, and immune regulation. A more effective combination treatment concerning with pimozide is being under investigation.

Cell cycle regulatory markers in melanoma: New strategies in diagnosis and treatment

Background: Melanoma has been known as an aggressive type of skin cancer in recent years. Reports have distributed the spread rate of melanoma among white skin populations. Also, many studies have mentioned several causes of melanoma. Ultraviolet radiation was represented to be the most important reason for occurrence of melanoma. However, recent studies have found that a combination of factors, such as environmental and genetic factors, can contribute to occurrence of various cancers, specifically melanoma.

Methods: Different studies have been conducted on the efficacy of genetic disorders in melanoma. These surveys marked the key role of specific biomarkers in molecular and cellular processes, and investigations have found the expression of several genes in these processes. In addition, aberrant expression of these genes due to mutation and methylation can affect the whole process.

Results: The expression process of these genes is regulated by microRNAs. These new biomolecules have been considered as negative regulators because of managing molecular and cellular processes. MicroRNAs are small conserved regulators attached to their targets leading to rearrangement of gene expression. Adherence of these noncoding RNAs can cause mRNA degradation or inhibit its translation.

Conclusion: Recently, the application of specific genes in melanoma has been studied. In this review, the way melanoma is regulated because of these biomarkers and their demand through cell cycle in diagnosis, prognosis, and therapeutic periods was considered. Keywords: Melanoma, Biomarkers, Cell cycle, Biomolecules

Rsf‑1 regulates malignant melanoma cell viability and chemoresistance via NF‑κB/Bcl‑2 signaling

Remodeling and spacing factor 1 (Rsf-1) has been reported as overexpressed in numerous cancers; however, its expression, biological functions and mechanisms in malignant melanoma remain unknown. In the present study, the expression of Rsf-1 was investigated in 50 cases of malignant melanoma samples using immunohistochemistry. The results revealed that Rsf-1 expression was elevated in 38% of specimens. MTT, colony formation, Transwell and flow cytometry assays were performed to investigate the functions of Rsf-1. Knockdown of Rsf-1 in the MV3 and A375 melanoma cell lines decreased the viability, invasion and cell cycle transition of cells. Conversely, overexpression of Rsf-1 in M14 cells with low endogenous Rsf-1 expression induced opposing effects. Further analysis revealed that Rsf-1 knockdown decreased matrix metalloproteinase-2, cyclin E and phosphorylated-IκB expression. Additionally, Rsf-1 depletion reduced cisplatin resistance and significantly increased the cisplatin-associated apoptotic rate, whereas Rsf-1 overexpression exhibited opposing effects. Rsf-1 also maintained the mitochondrial membrane potential following cisplatin treatment. Analysis of apoptosis-associated proteins revealed that Rsf-1 positively regulated B-cell lymphoma 2 (Bcl-2), cellular inhibitor of apoptosis 1 (cIAP1) and cIAP2, and downregulated Bcl-2-associated X protein expression. Nuclear factor κ-light-chain-enhancer of activated B-cells (NF-κB) inhibition reversed the effects of Rsf-1 on Bcl-2. In conclusion, Rsf-1 was overexpressed in malignant melanoma and may contribute to the malignant behaviors of melanoma cells, possibly via the regulation of NF-κB signaling. Therefore, Rsf-1 may be a potential therapeutic target in the treatment of malignant melanoma.

UVA, metabolism and melanoma: UVA makes melanoma hungry for metastasis

Ultraviolet (UV) radiation has a plethora of effects on human tissues. In the UV spectrum, wavelengths above 320 nm fall into the UVA range, and for these, it has been shown that they induce reactive oxygen species (ROS), DNA mutations and are capable to induce melanoma in mice. In addition to this, it was recently shown that UVA irradiation and UVA-induced ROS also increase glucose metabolism of melanoma cells. UVA irradiation causes a persistent increase in glucose consumption, accompanied by increased glycolysis, increased lactic acid production and activation of the pentose phosphate pathway. Furthermore, it was shown that the enhanced secretion of lactic acid is important for invasion of melanoma in vitro. The current knowledge of this link between UVA, metabolism and melanoma, possible mechanisms of UVA-induced glucose metabolism and their starting points are discussed in this review with focus on ROS- and UVA-induced cellular stress signalling, DNA damage signalling and DNA repair systems. When looking at the benefits of UVA-induced glucose metabolism, it becomes apparent that there are more advantages of these metabolic changes than one would expect. Besides the role of lactic acid as initiator of protease expression and invasion, its role for immune escape of melanoma cells and the pentose phosphate pathway-derived nicotinamide adenine dinucleotide phosphate (NADPH) as part of a ROS detoxification strategy are discussed.

Decline in arylsulfatase B leads to increased invasiveness of melanoma cells

Arylsulfatase B (ARSB; N-acetylgalactosamine 4-sulfatase) is reduced in several malignancies, but levels in melanoma have not been investigated previously. Experiments were performed in melanoma cell lines to determine ARSB activity and impact on melanoma invasiveness. ARSB activity was reduced ~50% in melanoma cells compared to normal melanocytes. Silencing ARSB significantly increased the mRNA expression of chondroitin sulfate proteoglycan(CSPG)4 and pro-matrix metalloproteinase(MMP)-2, known mediators of melanoma progression. Also, invasiveness and MMP activity increased when ARSB was reduced, and recombinant ARSB inhibited invasiveness and MMP activity. Since the only known function of ARSB is to remove 4-sulfate groups from the N-acetylgalactosamine 4-sulfate residue at the non-reducing end of chondroitin 4-sulfate (C4S) or dermatan sulfate, experiments were performed to determine the transcriptional mechanisms by which expression of CSPG4 and MMP2 increased. Promoter activation of CSPG4 was mediated by reduced binding of galectin-3 to C4S when ARSB activity declined. In contrast, increased pro-MMP2 expression was mediated by increased binding of the non-receptor tyrosine phosphatase SHP2 to C4S. Increased phospho-ERK1,2 resulted from SHP2 inhibition. Combined effects of increased C4S, CSPG4, and MMP2 increased the invasiveness of the melanoma cells, and therapy with recombinant ARSB may inhibit melanoma progression.

Inhibition of p38 and ERK1/2 pathways by Sparstolonin B suppresses inflammation-induced melanoma metastasis

BACKGROUND

Cancer related inflammation plays a fatal role in the metastatic process, which can foster tumor growth, angiogenesis and dissemination. Sparstolonin B (SsnB), derived from Chinese medicine of the tubers of Scirpus yagara, is a TLR2 and TLR4 antagonists. It has exhibited multiple activities of anti-inflammatory, anti-cancer, anti-obesity and anti-hepatitis. However, whether SsnB is involved in the regulation of inflammation-induced tumor metastasis is not well elucidated.

PURPOSE

The aim of this study was to investigate the effectiveness of SsnB as a treatment of inflammation-induced tumor metastasis and identify the underlying mechanisms of its anti-tumor metastatic activity.

METHOD

The anti-tumor metastatic activity in vitro was estimated by MTT, wound-healing assay, matrigel invasion analysis and extracellular matrix adhesion assay. Mice lung metastasis and hepatic metastasis experiments were performed to assess the activities in vivo. Lungs or livers were weighed and the number of metastatic nodules was determined after mice were sacrificed. The levels of pro-inflammatory cytokines in the serum, lungs and livers were detected by using enzyme-linked immunosorbent assay (ELISA). Micro-metastasis nodules in lungs or livers were analyzed by histological examination. Immunohistochemistry and western blot analysis were conducted to determine protein expression.

RESULT

Herein, SsnB dose-dependently inhibited cell migration and invasion in mouse melanoma B16 cells with or without stimulation of lipopolysaccharide (LPS), Pam3csk4 or molecules from damaged tumor cells (DTC-Ms). The expression of matrix metalloproteinases (MMP)-2 was also significantly abated by SsnB in LPS-modulated B16 cells. And SsnB reduced LPS-activated B16 cells adhesion to extracellular matrix components collagen I and fibronectin in a dose-dependent manner. In vivo, SsnB obviously attenuated LPS-activated pulmonary metastasis in mice by reduction the number of metastatic nodules on the lung surfaces, lung weight and levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in serums and lungs. Moreover, in experimental hepatic metastasis model mice, SsnB remarkably repressed LPS-stimulated the number of metastatic nodules along with liver weight; and SsnB significantly suppressed LPS-activated increase levels of TNF-α and IL-6 in livers. Immunohistochemistry analysis indicated that SsnB inhibited the expression of TLR4 in livers. Furthermore, SsnB remarkably blocked p38 and ERK1/2 signaling pathway in LPS-induced B16 cells. P38 and ERK1/2 signaling silencing, using BIRB0796 (small molecular inhibitor of p38 MAPK) and PD184352 (inhibitor of MEK1/2 kinases that activate ERK1/2), significantly abated LPS-induced migration and invasion of B16 cells.

CONCLUSION

The present study reports a novel use of SsnB in mitigating TLRs ligands-induced melanoma metastasis by inhibition of p38 and ERK1/2 pathway.

Uncovering the anticancer mechanism of Compound Kushen Injection against HCC by integrating quantitative analysis, network analysis and experimental validation

Compound Kushen Injection (CKI) is a Traditional Chinese Medicine (TCM) preparation that has been clinically used in China to treat various types of solid tumours. Although several studies have revealed that CKI can inhibit the proliferation of hepatocellular carcinoma (HCC) cell lines, the active compounds, potential targets and pathways involved in these effects have not been systematically investigated. Here, we proposed a novel idea of “main active compound-based network pharmacology” to explore the anti-cancer mechanism of CKI. Our results showed that CKI significantly suppressed the proliferation and migration of SMMC-7721 cells. Four main active compounds of CKI (matrine, oxymatrine, sophoridine and N-methylcytisine) were confirmed by the integration of ultra-performance liquid chromatography/mass spectrometry (UPLC-MS) with cell proliferation assays. The potential targets and pathways involved in the anti-HCC effects of CKI were predicted by a network pharmacology approach, and some of the crucial proteins and pathways were further validated by western blotting and metabolomics approaches. Our results indicated that CKI exerted anti-HCC effects via the key targets MMP2, MYC, CASP3, and REG1A and the key pathways of glycometabolism and amino acid metabolism. These results provide insights into the mechanism of CKI by combining quantitative analysis of components, network pharmacology and experimental validation.

Neutralization of matrix metalloproteinase-9 potentially enhances oncolytic efficacy of tanapox virus for melanoma therapy

Matrix metalloproteinases (MMPs), which are involved in degradation of extracellular matrix, are critical regulators in tumor progression, metastasis and angiogenesis. Although induction of MMPs is frequently observed during the viral infection, the effect of MMPs on viral replication varies between viruses. MMP-9, for instance, is upregulated and promotes the replication of some viruses, such as herpes simplex virus, but inhibits the replication of others. Here, we report that infection with tanapox virus (TPV) promotes the expression of MMP-9 in the melanoma cells. In addition, we show that MMP-9 exerts an anti-viral effect on TPV replication and plays a protective role in TPV-infected melanoma cells in vitro. Moreover, the neutralization of MMP-9 in melanoma cells remarkably enhances the TPV infection and leads to a significant reduction in cell survival. In summary, this study contributes to understanding of the role played by MMP-9 in TPV infectivity and provides more insights for using TPV as cancer virotherapy in future studies. Since TPV has shown substantial oncolytic efficacy in promoting melanoma tumor regression in animal models, identifying mechanisms that suppress MMP-9 expression upon TPV infection can potentially improve its use as a melanoma virotherapy.

Melanoma long non-coding RNA signature predicts prognostic survival and directs clinical risk-specific treatments

BACKGROUND

Various studies have demonstrated that the Breslow thickness, tumor ulceration and mitotic index could serve as prognostic markers in patients with cutaneous melanoma. Recently, however, as these clinicopathological biomarkers lack efficient interpretation of endogenous mechanism of melanoma, the emphasis on the prognosis of melanoma has transformed to molecular tumor markers.

OBJECTIVE

This study was designed to identify survival-related long non-coding RNAs (lncRNAs), and based on the different expressions of these lncRNAs, clinical risk-specific diagnosis and adjuvant therapy could be employed on melanoma patients, especially patients in the early course of disease or patients with a Breslow thickness no more than 2mm.

METHODS

The clinical information and corresponding RNA expression data were obtained from The Cancer Genome Atlas dataset and Gene Expression Omnibus dataset (GSE65904). All samples were categorized into one training dataset and two validation datasets. Cox proportional hazard regression analysis was then used to identify survival-related lncRNAs and risk assessment signature was constructed in training dataset. Kaplan-Meier method was used to estimate the utility of this signature in predicting the duration of survival of patients both in the training dataset and two validation datasets. Meanwhile receiver operating characteristic analyses were used to evaluate the predictive effectiveness of this signature in two validation datasets.

RESULTS

It was found that the signature was effective while used for risk stratification, and Kaplan-Meier analyses indicated that the duration of survival of patients in high-risk groups were significantly shorter than that of low-risk groups. Moreover, areas under the receiver operating characteristic curve were 0.711 (95% confidence interval: 0.618-0.804) and 0.698 (95% confidence interval: 0.614-0.782) when this signature was used to predict the patients' duration of survival in two validation datasets respectively, indicating the superior specificity and sensitivity of this signature.

CONCLUSION

We identified a four-lncRNA prognostic signature with the ability of risk stratification for melanoma patients. Risk score acquired from this signature, combining with differential diagnosis and differential adjuvant therapy, could potentially improve the prognosis quality of life for patients, especially patients in the early course of disease or patients with a Breslow thickness no more than 2mm.

S100A4 Elevation Empowers Expression of Metastasis Effector Molecules in Human Breast Cancer

Many human glandular cancers metastasize along nerve tracts, but the mechanisms involved are generally poorly understood. The calcium-binding protein S100A4 is expressed at elevated levels in human cancers, where it has been linked to increased invasion and metastasis. Here we report genetic studies in a Drosophila model to define S100A4 effector functions that mediate metastatic dissemination of mutant Ras-induced tumors in the developing nervous system. In flies overexpressing mutant RasVal12 and S100A4, there was a significant increase in activation of the stress kinase JNK and production of the matrix metalloproteinase MMP1. Genetic or chemical blockades of JNK and MMP1 suppressed metastatic dissemination associated with S100A4 elevation, defining required signaling pathway(s) for S100A4 in this setting. In clinical specimens of human breast cancer, elevated levels of the mammalian paralogs MMP2, MMP9, and MMP13 are associated with a 4- to 9-fold relative decrease in patient survival. In individual tumors, levels of MMP2 and MMP13 correlated more closely with levels of S100A4, whereas MMP9 levels correlated more closely with the S100 family member S100P. Overall, our results suggest the existence of evolutionarily conserved pathways used by S100A4 to promote metastatic dissemination, with potential prognostic and therapeutic implications for metastasis by cancers that preferentially exploit nerve tract migration routes. Cancer Res; 77(3); 780-9. ©2016 AACR.

Protein kinase C inhibitor Gö6976 but not Gö6983 induces the reversion of E- to N-cadherin switch and metastatic phenotype in melanoma: identification of the role of protein kinase D1

Background

Melanoma is a highly metastatic type of cancer that is resistant to all standard anticancer therapies and thus has a poor prognosis. Therefore, metastatic melanoma represents a significant clinical problem and requires novel and effective targeted therapies. The protein kinase C (PKC) family comprises multiple isoforms of serine/threonine kinases that possess distinct roles in cancer development and progression. In this study, we determined whether inhibition of PKC could revert a major process required for melanoma progression and metastasis; i.e. the E- to N-cadherin switch.

Methods

The cadherin switch was analyzed in different patient-derived primary tumors and their respective metastatic melanoma cells to determine the appropriate cellular model (aggressive E-cadherin-negative/N-cadherin-positive metastasis-derived melanoma cells). Next, PKC inhibition in two selected metastatic melanoma cell lines, was performed by using either pharmacological inhibitors (Gö6976 and Gö6983) or stable lentiviral shRNA transduction. The expression of E-cadherin and N-cadherin was determined by western blot. The consequences of cadherin switch reversion were analyzed: cell morphology, intercellular interactions, and β-catenin subcellular localization were analyzed by immunofluorescence labeling and confocal microscopy; cyclin D1 expression was analyzed by western blot; cell metastatic potential was determined by anchorage-independent growth assay using methylcellulose as semi-solid medium and cell migration potential by wound healing and transwell assays.

Results

Gö6976 but not Gö6983 reversed the E- to N-cadherin switch and as a consequence induced intercellular interactions, profound morphological changes from elongated mesenchymal-like to cuboidal epithelial-like shape, β-catenin translocation from the nucleus to the plasma membrane inhibiting its oncogenic function, and reverting the metastatic potential of the aggressive melanoma cells. Comparison of the target spectrum of these inhibitors indicated that these observations were not the consequence of the inhibition of conventional PKCs (cPKCs), but allowed the identification of a novel serine/threonine kinase, i.e. protein kinase Cμ, also known as protein kinase D1 (PKD1), whose specific inhibition allows the reversion of the metastatic phenotype in aggressive melanoma.

Conclusion

In conclusion, our study suggests, for the first time, that while cPKCs don’t embody a pertinent therapeutic target, inhibition of PKD1 represents a novel attractive approach for the treatment of metastatic melanoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-3007-5) contains supplementary material, which is available to authorized users.

(-)-Oleocanthal exerts anti-melanoma activities and inhibits STAT3 signaling pathway

Tumor angiogenesis, growth and metastasis are three closely related processes. We therefore explored the effects of (-)-oleocanthal (OC) on the three processes in melanoma and investigated underlying mechanisms. In vitro, OC suppressed proliferation, migration, invasion and induced apoptosis in melanoma cells. In addition, OC inhibited proliferation, migration, invasion and tube formation in human umbilical vascular endothelial cells. In vivo, it exhibited potent activity in suppressing tumor growth in a subcutaneous xenograft model. Furthermore, OC suppressed proliferation and angiogenesis as measured by immunohistochemical staining of Ki-67 and CD31. In addition, OC was found to inhibit metastasis of melanoma in a lung metastasis model. Mechanistically, OC significantly suppressed signal transducer and activator of transcription 3 (STAT3) phosphorylation, decreased STAT3 nuclear localization and inhibited STAT3 transcriptional activity. OC also downregulated STAT3 target genes, including Mcl-1, Bcl-xL, MMP-2, MMP-9, VEGF, which are involved in apoptosis, invasion and angiogenesis of melanoma. These results support further investigation of OC as a potential anti-melanoma drug.

Melanoma Brain Metastasis: Mechanisms, Models, and Medicine

The development of brain metastases in patients with advanced stage melanoma is common, but the molecular mechanisms responsible for their development are poorly understood. Melanoma brain metastases cause significant morbidity and mortality and confer a poor prognosis; traditional therapies including whole brain radiation, stereotactic radiotherapy, or chemotherapy yield only modest increases in overall survival (OS) for these patients. While recently approved therapies have significantly improved OS in melanoma patients, only a small number of studies have investigated their efficacy in patients with brain metastases. Preliminary data suggest that some responses have been observed in intracranial lesions, which has sparked new clinical trials designed to evaluate the efficacy in melanoma patients with brain metastases. Simultaneously, recent advances in our understanding of the mechanisms of melanoma cell dissemination to the brain have revealed novel and potentially therapeutic targets. In this review, we provide an overview of newly discovered mechanisms of melanoma spread to the brain, discuss preclinical models that are being used to further our understanding of this deadly disease and provide an update of the current clinical trials for melanoma patients with brain metastases.

UVA-Irradiation Induces Melanoma Invasion via the Enhanced Warburg Effect

Melanoma is a malignant tumor in which UVA (320-400 nm) radiation is considered to be an important risk factor. But the role of UVA in melanoma progression toward an invasive phenotype is still not adequately investigated. For most proliferating tumor cells the preference of aerobic glycolysis has been described as the Warburg effect. Here we investigate the effect of UVA irradiation on changes in the Warburg effect and tumor progression toward invasive potential. On UVA irradiation, melanoma cell lines from initial tumors show an induction of the Warburg effect with increased glucose consumption and lactate production, which is at least partially mediated by reactive oxygen species. Associated with UVA treatment and enhanced lactic acid production, tumor-relevant proteases and in situ invasion is upregulated. Simultaneously, UVA increases intracellular concentrations of progression marker transketolase and activated protein kinase Akt, both involved in metabolic changes that increase with proliferation. Using invasion assays we show that lactic acid, resulting from the UVA enhanced and partially reactive oxygen species-mediated Warburg effect, increases the invasive potential of all melanoma cell lines investigated. Therefore, we demonstrate in melanoma cells that production of lactic acid, induced by UVA irradiation, increases invasiveness of melanoma cells via expression of tumor-relevant proteases.

Prognostic significance of the expression of nuclear eukaryotic translation initiation factor 5A2 in human melanoma

Eukaryotic translation initiation factor 5A2 (EIF5A2) expression is upregulated in various cancers. The present authors previously demonstrated that cytoplasmic EIF5A2 expression increases with melanoma progression and inversely correlates with patient survival. Other studies have suggested that nuclear EIF5A2 may also play a role in oncogenesis. The present study used immunohistochemistry and tissue microarray with a large number of melanocytic lesions (n=459) and demonstrated that nuclear EIF5A2 expression was significantly upregulated between common acquired nevi, dysplastic nevi and primary melanomas, and between primary melanomas and metastatic melanomas. Nuclear EIF5A2 expression was inversely associated with overall and disease-specific 5-year survival rate for all (P<0.001) and primary (P=0.014 and P=0.015, respectively) melanoma patients. Nuclear EIF5A2 expression was directly associated with melanoma thickness (P=0.036) and American Joint Committee on Cancer staging (P<0.001), which suggests the possible role of nuclear EIF5A2 in melanoma cell invasion. Subsequently, the present study investigated the association between the expression of nuclear EIF5A2 and matrix metalloproteinase-2 (MMP-2), which is an important factor for promoting cancer cell invasion. Nuclear EIF5A2 and a strong MMP-2 expression were directly associated, and their concurrent expression was significantly associated with a poorer overall and disease-specific 5-year survival rate for all and primary melanoma patients. Nuclear and cytoplasmic EIF5A2 expression were also demonstrated to be significantly associated, and simultaneous expression of the two forms of EIF5A2 was significantly associated with poor overall and disease-specific 5-year survival rates for all and primary melanoma patients. Multivariate Cox regression analysis revealed that nuclear EIF5A2 expression alone and in combination with cytoplasmic EIF5A2 expression was an adverse independent prognostic factor for all and primary melanoma patients. In conclusion, the present study for the first time, to the best of our knowledge, demonstrated that nuclear EIF5A2 expression is an independent prognostic marker in melanoma, and revealed its role in melanoma progression and patient survival. Therefore, nuclear EIF5A2 may have the potential to serve as a therapeutic marker for melanoma.

High LIFr expression stimulates melanoma cell migration and is associated with unfavorable prognosis in melanoma

Increased or decreased expression of LIF receptor (LIFr) has been reported in several human cancers, including skin cancer, but its role in melanoma is unknown. In this study, we investigated the expression pattern of LIFr in melanoma and assessed its prognostic value. Using tissue microarrays consisting of 441 melanomas and 96 nevi, we found that no normal nevi showed high LIFr expression. LIFr staining was significantly increased in primary melanoma compared to dysplastic nevi (P = 0.0003) and further increased in metastatic melanoma (P = 0.0000). Kaplan–Meier survival curve and univariate Cox regression analyses showed that increased expression of LIFr was correlated with poorer 5-year patient survival (overall survival, P = 0.0000; disease-specific survival, P = 0.0000). Multivariate Cox regression analyses indicated that increased LIFr expression was an independent prognostic marker for primary melanoma (P = 0.036). LIFr knockdown inhibited melanoma cell migration in wound healing assays and reduced stress fiber formation. LIFr knockdown correlated with STAT3 suppression, but not YAP, suggesting that LIFr activation might stimulate melanoma cell migration through the STAT3 pathway. Our data indicate that strong LIFr expression identifies potentially highly malignant melanocytic lesions at an early stage and LIFr may be a potential target for the development of early intervention therapeutics.

Vemurafenib resistance increases melanoma invasiveness and modulates the tumor microenvironment by MMP-2 upregulation

The BRAF(V600E) mutation confers constitutive kinase activity and accounts for >90% of BRAF mutations in melanoma. This genetic alteration is a current therapeutic target; however, the antitumorigenic effects of the BRAF(V600E) inhibitor vemurafenib are short-lived and the majority of patients present tumor relapse in a short period after treatment. Characterization of vemurafenib resistance has been essential to the efficacy of next generation therapeutic strategies. Herein, we found that acute BRAF inhibition induced a decrease in active MMP-2, MT1-MMP and MMP-9, but did not modulate the metalloproteinase inhibitors TIMP-2 or RECK in naïve melanoma cells. In vemurafenib-resistant melanoma cells, we observed a lower growth rate and an increase in EGFR phosphorylation followed by the recovery of active MMP-2 expression, a mediator of cancer metastasis. Furthermore, we found a different profile of MMP inhibitor expression, characterized by TIMP-2 downregulation and RECK upregulation. In a 3D spheroid model, the invasion index of vemurafenib-resistant melanoma cells was more evident than in its non-resistant counterpart. We confirmed this pattern in a matrigel invasion assay and demonstrated that use of a matrix metalloproteinase inhibitor reduced the invasion of vemurafenib resistant melanoma cells but not drug naïve cells. Moreover, we did not observe a delimited group of cells invading the dermis in vemurafenib-resistant melanoma cells present in a reconstructed skin model. The same MMP-2 and RECK upregulation profile was found in this 3D skin model containing vemurafenib-resistant melanoma cells. Acute vemurafenib treatment induces the disorganization of collagen fibers and consequently, extracellular matrix remodeling, with this pattern observed even after the acquisition of resistance. Altogether, our data suggest that resistance to vemurafenib induces significant changes in the tumor microenvironment mainly by MMP-2 upregulation, with a corresponding increase in cell invasiveness.

Role of Matrix Metalloproteinases in Photoaging and Photocarcinogenesis

Matrix metalloproteinases (MMPs) are zinc-containing endopeptidases with an extensive range of substrate specificities. Collectively, these enzymes are able to degrade various components of extracellular matrix (ECM) proteins. Based on their structure and substrate specificity, they can be categorized into five main subgroups, namely (1) collagenases (MMP-1, MMP-8 and MMP-13); (2) gelatinases (MMP-2 and MMP-9); (3) stromelysins (MMP-3, MMP-10 and MMP-11); (4) matrilysins (MMP-7 and MMP-26); and (5) membrane-type (MT) MMPs (MMP-14, MMP-15, and MMP-16). The alterations made to the ECM by MMPs might contribute in skin wrinkling, a characteristic of premature skin aging. In photocarcinogenesis, degradation of ECM is the initial step towards tumor cell invasion, to invade both the basement membrane and the surrounding stroma that mainly comprises fibrillar collagens. Additionally, MMPs are involved in angiogenesis, which promotes cancer cell growth and migration. In this review, we focus on the present knowledge about premature skin aging and skin cancers such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma, with our main focus on members of the MMP family and their functions.

Inhibition of the STAT3 signaling pathway contributes to apigenin-mediated anti-metastatic effect in melanoma

Signal transducer and activator of transcription 3 (STAT3) signaling is constantly activated in human melanoma, and promotes melanoma metastasis. The dietary flavonoid apigenin is a bioactive compound that possesses low toxicity and exerts anti-metastatic activity in melanoma. However, the anti-metastasis mechanism of apigenin has not been fully elucidated. In the present study, we showed that apigenin suppressed murine melanoma B16F10 cell lung metastasis in mice, and inhibited cell migration and invasion in human and murine melanoma cells. Further study indicated that apigenin effectively suppressed STAT3 phosphorylation, decreased STAT3 nuclear localization and inhibited STAT3 transcriptional activity. Apigenin also down-regulated STAT3 target genes MMP-2, MMP-9, VEGF and Twist1, which are involved in cell migration and invasion. More importantly, overexpression of STAT3 or Twist1 partially reversed apigenin-impaired cell migration and invasion. Our data not only reveal a novel anti-metastasis mechanism of apigenin but also support the notion that STAT3 is an attractive and promising target for melanoma treatment.

Lentiviral-mediated overexpression of long non-coding RNA GAS5 reduces invasion by mediating MMP2 expression and activity in human melanoma cells

The present study evaluated the effects of long non-coding RNA GAS5 on the migration and invasion of melanoma cells. Using the SK-Mel‑110 melanoma cell line, we stably expressed GAS5, visualized the distribution of GAS5 by RNA fluorescence in situ hybridization (FISH) and examined changes in cell migration and invasion with Transwell assays. In GAS5 overexpressed SK-Mel‑110 cells, migrated and invaded cells decreased by 65.3 and 55.6%, respectively. Moreover, the MMP2 protein level, and its activity was downregulated by 67.9 and 15.8%, respectively. Overexpressing lncRNA GAS5 inhibited the migration and invasion ability of melanoma SK-Mel‑110 cells, partially by decreasing the MMP2 expression and its activity. This study is the first to reveal a potential relationship between lncRNA GAS5 and the migration and invasion of melanoma.

Loss of tumor suppressors KAI1 and p27 identifies a unique subgroup of primary melanoma patients with poor prognosis

Primary melanoma, a highly aggressive malignancy, exhibits heterogeneity in biologic behaviors, clinical characteristics, metastasis potential and mortality. The present study sought to identify the molecular signatures that define a subgroup of primary melanomas with high risks of metastasis and mortality. First, we identified the markers that best differentiated metastatic melanomas from primary melanomas by examining the expression of seven previously reported biomarkers (BRAF, Dicer, Fbw7, KAI1, MMP2, p27 and Tip60) in a training cohort consisting of 145 primary melanomas and 105 metastatic melanomas. KAI1 and p27, both tumor suppressors, emerged as best candidates. Loss of both tumor suppressors occurred in the majority (74.29%) of metastatic melanomas. Further, a subset (metastatic like, or "ML", 33.10%) of primary melanomas also lost these two tumor suppressors. Kaplan-Meier analysis indicated that ML subgroup of primary melanoma patients had much worse 5 year survival compared with other primary melanoma patients (P = 0.002). The result was confirmed in an independent validation cohort with 92 primary melanomas (P = 0.030) and in the combined cohort with 237 melanoma patients (P = 3.00E-4). Additionally, compared to KAI1 and p27 as an individual prognostic marker, the combined signature is more closely associated with melanoma patient survival (P = 0.025, 0.264 and 0.009, respectively). In conclusion, loss of both KAI1 and p27 defines a subgroup of primary melanoma patients with poor prognosis. This molecular signature may help in metastatic melanoma diagnosis and may provide information useful in identifying high-risk primary melanoma patients for more intensive clinical surveillance in the future.

A Novel Fully Humanized 3D Skin Equivalent to Model Early Melanoma Invasion

Metastatic melanoma remains incurable, emphasizing the acute need for improved research models to investigate the underlying biologic mechanisms mediating tumor invasion and metastasis, and to develop more effective targeted therapies to improve clinical outcome. Available animal models of melanoma do not accurately reflect human disease and current in vitro human skin equivalent models incorporating melanoma cells are not fully representative of the human skin microenvironment. We have developed a robust and reproducible, fully humanized three-dimensional (3D) skin equivalent comprising a stratified, terminally differentiated epidermis and a dermal compartment consisting of fibroblast-generated extracellular matrix. Melanoma cells incorporated into the epidermis were able to invade through the basement membrane and into the dermis, mirroring early tumor invasion in vivo. Comparison of our novel 3D melanoma skin equivalent with melanoma in situ and metastatic melanoma indicates that this model accurately recreates features of disease pathology, making it a physiologically representative model of early radial and vertical growth-phase melanoma invasion.

Increased expression of neuropilin 1 in melanoma progression and its prognostic significance in patients with melanoma

Neuropilin 1 (NRP1), a receptor of vascular endothelial growth factor (VEGF), promotes angiogenesis, tumor growth, tumor invasion and metastasis. However, the function of NRP1 in melanoma progression, as well as the effect of NRP1 expression on the prognosis of patients with melanoma remains unknown. In the present study, NRP1 expression was examined in 460 cases of melanocytic lesions (28 common nevi, 51 dysplastic nevi, 250 primary melanoma and 131 metastatic melanoma) at different stages, using a tissue microarray. The correlation of NRP1 expression with melanoma progression, and its prognostic value in patients with melanoma was examined. In addition, the correlation between matrix metalloproteinase 2 (MMP2) and NRP1 expression in patients with melanoma was analyzed. The results demonstrated that NRP1 expression was significantly increased in primary (56%) and metastatic melanoma (62%), compared with common nevi (11%) and dysplastic nevi (24%). Notably, increased NRP1 expression was correlated with a poorer overall, and disease-specific, 10-year survival (P=0.03 and P=0.002, respectively). Multivariate Cox regression analyses indicated that NRP1 is an independent prognostic marker for melanoma. Furthermore, a significant positive correlation between NRP1 and MMP2 expression in melanoma biopsies was observed, and their concomitant expression was closely correlated with melanoma patient survival, further supporting the hypothesis that the expression of NRP1 is associated with melanoma invasion and metastasis. In conclusion, increased NRP1 expression is associated with disease progression and reduced survival in patients with melanoma, and is a promising prognostic molecular marker for this disease.

Multifunctional bioscaffolds for 3D culture of melanoma cells reveal increased MMP activity and migration with BRAF kinase inhibition

Matrix metalloproteinases (MMPs) are important for many different types of cancer-related processes, including metastasis. Understanding the functional impact of changes in MMP activity during cancer treatment is an important facet not typically evaluated as part of preclinical research. With MMP activity being a critical component of the metastatic cascade, we designed a 3D hydrogel system to probe whether pharmacological inhibition affected human melanoma cell proteolytic activity; metastatic melanoma is a highly aggressive and drug-resistant form of skin cancer. The relationship between MMP activity and drug treatment is unknown, and therefore we used an in situ fluorogenic MMP sensor peptide to determine how drug treatment affects melanoma cell MMP activity in three dimensions. We encapsulated melanoma cells from varying stages of progression within PEG-based hydrogels to examine the relationship between drug treatment and MMP activity. From these results, a metastatic melanoma cell line (A375) and two inhibitors that inhibit RAF (PLX4032 and sorafenib) were studied further to determine whether changes in MMP activity led to a functional change in cell behavior. A375 cells exhibited increased MMP activity despite an overall decrease in metabolic activity with PLX4032 treatment. The changes in proteolytic activity correlated with increased cell elongation and increased single-cell migration. In contrast, sorafenib did not alter MMP activity or cell motility, showing that the changes induced by PLX4032 were not a universal response to small-molecule inhibition. Therefore, we argue the importance of studying MMP activity with drug treatment and its possible implications for unwanted side effects.

Stage-specific prognostic biomarkers in melanoma

The melanoma staging system proposed by the American Joint Committee on Cancer (AJCC) (which classifies melanoma patients into four clinical stages) is currently the most widely used tool for melanoma prognostication, and clinical management decision making by clinicians. However, multiple studies have shown that melanomas within specific AJCC Stages can exhibit varying progression and clinical outcomes. Thus, additional information, such as that provided by biomarkers is needed to assist in identifying the patients at risk of disease progression. Having previously found six independent prognostic biomarkers in melanoma, including BRAF, MMP2, p27, Dicer, Fbw7 and Tip60, our group has gone on to investigate if these markers are useful in risk stratification of melanoma patients in individual AJCC stages. First, we performed Kaplan-Meier survival and Cox proportional multivariate analyses comparing prognostication power of these markers in 254 melanoma patients for whom the expression levels were known, identifying the best performing markers as candidates for stage-specific melanoma markers. We then verified the results by incorporating an additional independent cohort (87 patients) and in a combined cohort (341 patients). Our data indicate that BRAF and MMP2 are optimal prognostic biomarkers for AJCC Stages I and II, respectively (P = 0.010, 0.000, Log-rank test); whereas p27 emerged as a good marker for AJCC Stages III/IV (0.018, 0.046, respectively, log-rank test). Thus, our study has identified stage-specific biomarkers in melanoma, a finding which may assist clinicians in designing improved personalized therapeutic modalities.

Fad104, a positive regulator of adipocyte differentiation, suppresses invasion and metastasis of melanoma cells by inhibition of STAT3 activity

Metastasis is the main cause of death in patients with cancer, and understanding the mechanisms of metastatic processes is essential for the development of cancer therapy. Although the role of several cell adhesion, migration or proliferation molecules in metastasis is established, a novel target for cancer therapy remains to be discovered. Previously, we reported that fad104 (factor for adipocyte differentiation 104), a regulatory factor of adipogenesis, regulates cell adhesion and migration. In this report, we clarify the role of fad104 in the invasion and metastasis of cancer cells. The expression level of fad104 in highly metastatic melanoma A375SM cells was lower than that in poorly metastatic melanoma A375C6 cells. Reduction of fad104 expression enhanced the migration and invasion of melanoma cells, while over-expression of FAD104 inhibited migration and invasion. In addition, melanoma cells stably expressing FAD104 showed a reduction in formation of lung colonization compared with control cells. FAD104 interacted with STAT3 and down-regulated the phosphorylation level of STAT3 in melanoma cells. These findings together demonstrate that fad104 suppressed the invasion and metastasis of melanoma cells by inhibiting activation of the STAT3 signaling pathway. These findings will aid a comprehensive description of the mechanism that controls the invasion and metastasis of cancer cells.

Evaluating biomarkers in melanoma

The incidence of cutaneous melanoma has more than doubled over the last decades making it one of the fastest rising cancers worldwide. Improved awareness and early detection of malignant moles now permit earlier diagnosis aiming to decrease the likelihood of recurrence. However, it is difficult to identify those patients initially diagnosed with localized melanoma who subsequently develop metastatic disease. For this group, prognosis remains poor and clinical outcomes are variable and challenging to predict. Considerable efforts have focused on the search for novel prognostic tools, with numerous markers evaluated in the circulation and in tumor lesions. The most reliable predictors of patient outcome are the clinical and histological features of the primary tumor such as Breslow thickness, ulceration status, and mitotic rate. Elevated serum levels of the enzyme lactate dehydrogenase, likely to indicate active metastatic disease, are also routinely used to monitor patients. The emergence of novel immune and checkpoint antibody treatments for melanoma and increasing appreciation of key roles of the immune system in promoting or halting cancer progression have focused attention to immunological biomarkers. Validation of the most promising of these may have clinical applications in assisting prognosis, assessing endpoints in therapy, and monitoring responses during treatment.

eIF4E is an adverse prognostic marker of melanoma patient survival by increasing melanoma cell invasion

Human cutaneous melanoma is a devastating skin cancer because of its invasive nature and high metastatic potential. We used tissue microarray to study the role of human eukaryotic translation initiation factor 4E (eIF4E) in melanoma progression in 448 melanocytic lesions and found that high eIF4E expression was significantly increased in primary melanomas compared with dysplastic nevi (P<0.001), and further increased in metastatic melanomas (P<0.001). High eIF4E expression was associated with melanoma thickness (P=0.046), and poor overall and disease-specific 5-year survival of all, and primary melanoma patients, especially those with tumors ≥1 mm thick. Multivariate Cox regression analysis revealed that eIF4E is an independent prognostic marker. eIF4E knockdown (KD) in melanoma cells resulted in a significant increase in apoptosis (sub-G1 populations) and decrease in cell proliferation, and also resulted in downregulation of mesenchymal markers and upregulation of E-cadherin. In addition, eIF4E KD led to a decrease in melanoma cell invasion, matrix metalloproteinase-2 expression and activity, c-myc and BCL2 expression, and an increase in cleaved PARP and cleaved caspase-3 expression and chemosensitivity. Taken together, our data suggest that the eIF4E may promote melanoma cell invasion and metastasis, and may also serve as a promising prognostic marker and a potential therapeutic target for melanoma.

A study of ad-proline peptidomimetic inhibitor of melanoma and endothelial cell invasion through activity towards MMP-2 and MMP-9

Ad-proline peptidomimetic targeting MMP-2 and MMP-9 was identified from a pool of compounds following enzyme inhibition kinetics and Matrigel sponge assays, showing the capacity of blocking capillary network formationin vivo.

Metalloproteinases in melanoma

Tumour cell adhesion, motility, proteolytic activities and cell receptors have important roles in cancer invasion. These processes are involved from early development of melanoma within the epidermis, to tumour cell invasion of the underlying tissue until intravasation of lymphatic or blood vessels, and thereafter, dissemination into distant organs occur. The activity of several proteolytic enzymes was shown to be pivotal in promoting melanoma cell invasion. These enzymes not only remodel the extracellular matrix, but also release active factors and shed cell surface receptors thereby mediating melanoma cross-communication with their microenvironment. This leads to the generation of a favourable environment for melanoma growth. Several proteases are involved in melanoma invasion and include serine, cysteine proteases, matrix metalloproteases (MMPs) and the disintegrin and metalloproteases (ADAMs). This study summarises the current knowledge on the role of metalloproteinases, MMPs and ADAMs, in melanoma.