A spoonful of sugar makes the melanoma go: the role of heparan sulfate proteoglycans in melanoma metastasis

Efficient drug delivery by novel cell-penetrating peptide derived from Midkine, with two heparin binding sites braced by a length-specific helix

Cell-penetrating peptides (CPPs) have been regarded as potential drug carriers for cancer therapy. However, most well-studied CPPs fail to deliver exogenous drugs efficiently and selectively. In this study, a tumour-targeted CPP with high efficiency derived from heparin-binding domain (HBD) of Midkine (named HMD) was discovered. HMD exhibited higher delivery efficiency than classic CPPs (TAT and R9) and manifested selectivity in tumour cells. Normally, the positive charge is the key factor for the transmembrane activity of CPPs such as TAT and R9. Here, the length of α-helix inside CPP was found also important for in the recognition of heparan sulphate proteoglycans (HSPGs). Subsequently, the introduction of HMD enhanced the inhibitory effect of Momordica antiviral protein of 30 kDa (MAP30) on tumour cells, resulting in a 6.07-fold and 5.42-fold increase in HeLa cells and MGC80-3 cells respectively without enhanced cytotoxicity in normal cells. These results show that HMD possesses high efficiency and good tumour specificity and can be utilised as a promising agent for the tumour-targeted delivery of drug. This study is also a supplement to the existing theories about the biological activities of the α-helix in CPPs.

Identification of differentially expressed methylated genes in melanoma versus nevi using bioinformatics methods

Background

Melanoma is a highly invasive malignant skin tumor. While melanoma may share some similarities with that of melanocytic nevi, there also exist a number of distinct differences between these conditions. An analysis of these differences may provide a means to more effectively evaluate the etiology and pathogenesis of melanoma. In particular, differences in aberrant methylation expression may prove to represent a critical distinction.

Methods

Data from gene expression datasets (GSE3189 and GSE46517) and gene methylation datasets (GSE86355 and GSE120878) were downloaded from the GEO database. GEO2R was used to obtain differentially expressed genes (DEGs) and differentially methylation genes (DMGs). Function and pathway enrichment of selected genes were performed using the DAVID database. A protein-protein interaction (PPI) network was constructed by STRING while its visualization was achieved with use of cytoscape. Primary melanoma samples from TCGA were used to identify significant survival genes.

Results

There was a total of 199 genes in the hypermethylation-low expression group, while 136 genes in the hypomethylation-high expression group were identified. The former were enriched in the biological processes of transcription regulation, RNA metabolism and regulation of cell proliferation. The later were highly involved in cell cycle regulation. 13 genes were screened out after survival analysis and included: ISG20, DTL, TRPV2, PLOD3, KIF3C, DLGAP4, PI4K2A, WIPI1, SHANK2, SLC16A10, GSTA4O, LFML2A and TMEM47.

Conclusion

These findings reveal some of the methylated differentially expressed genes and pathways that exist between melonoma and melanocytic nevi. Moreover, we have identified some critical genes that may help to improve the diagnosis and treatment of melanoma.

Antitumor activity of sulforaphane in mice model of skin cancer via blocking sulfatase-2

Although there are many treatment options for skin cancer, the chemotherapeutic agents for skin cancer are linked with many adverse effects as well as the development of multidrug resistance. Sulforaphane is an isothiocyanate, which is found in cruciferous vegetables. Consumption of sulforaphane-rich diet has been linked to inhibition of UV-exposed skin carcinogenesis. Therefore, the goal of this study was to determine the ability of sulforaphane to reduce skin cancer in mice through inhibition of sulfatase-2 enzyme. Epicutaneous application of 7,12-dimethylbenz (a) anthracene was performed on the shaved dorsal skin of mice followed by croton oil. Sulforaphane (9 μmol/mouse/day) was administered to mice orally. Skin was removed from the dorsal area for assessment of sulfatase-2, glypican-3, heparan sulphate proteoglycans (HSPGs), nuclear factor (NF)κB, nuclear factor E2-related factor 2 (Nrf2), tumor necrosis factor (TNF)-α, IL-1β and caspase-3. In addition, skin sections were stained with haematoxylin/eosin, Mallory and cytokeratin immunostaining. We found that, sulforaphane blocked sulfatase-2 activity, leading to significant elevation in HSPGs as well as significant reduction in glypican-3. In addition, sulforaphane significantly activated Nrf2 and reduced both the gene and protein expression of NFκB, TNF-α, IL-1β and caspase-3. In parallel, stained sections obtained from skin cancer mice treated with sulforaphane showed significant reduction in hyperkeratosis, acanthosis and epithelial dysplasia. The collective results indicate that sulforaphane suppresses skin cancer via blocking sulfatase-2 with subsequent elevation in HSPGs and reduction in glypican-3. Moreover, sulforaphane attenuated skin cancer-induced activation of inflammatory and apoptotic pathways.

Chemistry of xylopyranosides

Xylose is one of the few monosaccharidic building blocks that are used by mammalian cells. In comparison with other monosaccharides, xylose is rather unusual and, so far, only found in two different mammalian structures, i.e. in the Notch receptor and as the linker between protein and glycosaminoglycan (GAG) chains in proteoglycans. Interestingly, simple soluble xylopyranosides can not only initiate the biosynthesis of soluble GAG chains but also function as inhibitors of important enzymes in the biosynthesis of proteoglycans. Furthermore, xylose is a major constituent of hemicellulosic xylans and thus one of the most abundant carbohydrates on Earth. Altogether, this has spurred a strong interest in xylose chemistry. The scope of this review is to describe synthesis of xylopyranosyl donors, as well as protective group chemistry, modifications, and conformational analysis of xylose.

Proteoglycans in Normal and Healing Skin

Significance: Proteoglycans have a distinct spatial localization in normal skin and are essential for the correct structural development, organization, hydration, and functional properties of this tissue. The extracellular matrix (ECM) is no longer considered to be just an inert supportive material but is a source of directive, spatial and temporal, contextual information to the cells via components such as the proteoglycans. There is a pressing need to improve our understanding of how these important molecules functionally interact with other matrix structures, cells and cellular mediators in normal skin and during wound healing. Recent Advances: New antibodies to glycosaminoglycan side chain components of skin proteoglycans have facilitated the elucidation of detailed localization patterns within skin. Other studies have revealed important proliferative activities of proteinase-generated fragments of proteoglycans and other ECM components (matricryptins). Knockout mice have further established the functional importance of skin proteoglycans in the assembly and homeostasis of the normal skin ECM. Critical Issues: Our comprehension of the molecular and structural complexity of skin as a complex, dynamic, constantly renewing, layered connective tissue is incomplete. The impact of changes in proteoglycans on skin pathology and the wound healing process is recognized as an important area of pathobiology and is an area of intense investigation. Future Directions: Advanced technology is allowing the development of new artificial skins. Recent knowledge on skin proteoglycans can be used to incorporate these molecules into useful adjunct therapies for wound healing and for maintenance of optimal tissue homeostasis in aging skin.

Heparan sulfate proteoglycans and heparin regulate melanoma cell functions

BACKGROUND

The solid melanoma tumor consists of transformed melanoma cells, and the associated stromal cells including fibroblasts, endothelial cells, immune cells, as well as, soluble macro- and micro-molecules of the extracellular matrix (ECM) forming the complex network of the tumor microenvironment. Heparan sulfate proteoglycans (HSPGs) are an important component of the melanoma tumor ECM. Importantly, there appears to be both a quantitative and a qualitative shift in the content of HSPGs, in parallel to the nevi-radial growth phase-vertical growth phase melanoma progression. Moreover, these changes in HSPG expression are correlated to modulations of key melanoma cell functions.

SCOPE OF REVIEW

This review will critically discuss the roles of HSPGs/heparin in melanoma development and progression.

MAJOR CONCLUSIONS

We have correlated HSPGs' expression and distribution with melanoma cell signaling and functions as well as angiogenesis.

GENERAL SIGNIFICANCE

The current knowledge of HSPGs/heparin biology in melanoma provides a foundation we can utilize in the ongoing search for new approaches in designing anti-tumor therapy. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.