The synthesis and structural characterization of graft copolymers composed of γ-PGA backbone and oligoesters pendant chains

© 2017 The Authors. Published by American Chemical Society. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1021/jasms.8b05393The novel copolymers composed of poly-γ-glutamic acid (γ-PGA) and oligoesters have been developed. The structures of the obtained copolymers including variety of end groups were determined at the molecular level with the aid of electrospray ionization multistage mass spectrometry (ESI-MSn). The fragmentation experiment performed for the selected sodium adducts of the copolymers confirmed that the developed methods lead to the formation of graft copolymers composed of poly-γ-glutamic acid (γ-PGA) backbone and oligoesters pendant chains. Moreover, it was established that fragmentation of selected sodium adducts of graft copolymers proceeded via random breakage of amide bonds along the backbone and ester bonds of the oligoesters pendant chains. Considering potential applications of the synthesized copolymers in the area of biomaterials, the hydrolytic degradation under laboratory conditions and in vitro cytotoxicity tests were performed. The ESI-MSn technique applied in this study has been proven to be a useful tool in structural studies of novel graft copolymers as well as their degradation products.This work was supported by the Polish National Science Centre (Decision No DEC-2013/11/N/ST5/01364

The role of epigenetics in the pathogenesis of melanoma

Epigenetics represents the mechanisms that influence the regulation and modification of the expression of genetic material not related to the alterations in DNA sequences. These mechanisms include both DNA methylation and histone modifications. In the present article, we review current views on the role of aberrations of DNA hyper- and hypomethylation processes and the acetylation of histones, associated with genes that control the cell cycle, cell differentiation, DNA repair, apoptosis, cell signaling, angiogenesis, metabolism of xenobiotics and invasion, in the pathogenesis of melanoma. In addition, new strategies for treatment of melanoma associated with epigenetics are presented.Przez pojęcie epigenetyka należy rozumieć mechanizmy wpływające na regulację i modyfi kację ekspresji materiału genetycznego, jednocześnie niezmieniające sekwencji nukleotydów. Mechanizmy te obejmują zarówno metylację DNA, jak i modyfikacje histonów. W artykule dokonano przeglądu aktualnych poglądów dotyczących zaburzeń procesów hiperihipometylacji DNA oraz acetylacji histonów w patogenezie czerniaka, związanych z genami kontrolującymi cykl komórkowy, różnicowanie, naprawę DNA, apoptozę, sygnalizację komórkową, angiogenezę, metabolizm ksenobiotyków i powstawanie przerzutów. Ponadto przedstawiono nowe strategie leczenia czerniaka związane z epigenetyką

Evaluation of Melanogenesis in A-375 Cells in the Presence of DMSO and Analysis of Pyrolytic Profile of Isolated Melanin

The increase of a skin malignant melanoma (melanoma malignum) incidence in the world has been observed in recent years. The tumour, especially in advanced stadium with metastases, is highly resistant to conventional treatment. One of the strategies is to modulate melanogenesis using chemical compounds. In this study, the processes of differentiation and melanogenesis induced by dimethylsulfoxide (DMSO) in human melanoma cells (A-375) were investigated. Natural melanin isolated from A-375 melanoma cell line treated with 0.3% DMSO was analyzed by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) method. The products derived from pheomelanin have not been stated in the pyrolytic profile of analyzed melanin. Within all products derived from eumelanins, 1,2-benzenediol has been predominated. It has been shown that in the melanoma cells stimulated with 0.3% and 1% DMSO, the increase of transcriptional activity of the tyrosinase gene took place. It was accompanied by the rise of tyrosinase activity and an accumulation of melanin in the cells. The better knowledge about the structure of melanins can contribute to establish the uniform criteria of malignant melanoma morbidity risk

Effect of polymer degradation on prolonged release of paclitaxel from filomicelles of polylactide/poly(ethylene glycol) block copolymers

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Changes in the cellular behaviour of human colonic cell line Caco-2 in response to butyrate treatment.

Gut-derived adenocarcinoma Caco-2 cells were treated with sodium butyrate (NaB) at physiologically relevant concentrations. We characterized its effects on proliferation, differentiation, apoptosis, adhesion to the solid support and interleukin-8 secretion. Differentiation was determined by brush border alkaline phosphatase activity. Apoptosis was assessed by acridine orange and Hoechst stains. Differentiation and apoptosis were analyzed in both adherent and floating cell populations. The transformed Caco-2 cells did not retain their malignant phenotype in the presence of NaB. They appeared to undergo a change in the phenotype induced by NaB, as indicated by reduced proliferation, enhanced differentiation, stimulation of apoptosis leading to decreased viability of cells, and stimulation of interleukin-8 secretion. Considering all the above facts and data, we postulate that Caco-2 cells cultured in NaB supplemented medium could regain the phenotypic characteristics of the phenotype of the parent cell from which originated the Caco-2 line

Quantitative analysis of the level of p53 and p21WAF1 mRNA in human colon cancer HT-29 cells treated with inositol hexaphosphate

The aim of this study was to analyze the molecular mechanism of inositol hexaphosphate (InsP6) action through which it may inhibit proliferation of colon cancer cells and cell cycle progression. A kinetic study of p53 and p21WAF1 mRNA increase was performed on human colon cancer HT-29 cells after treatment with 1, 5 and 10 mM InsP6 for 6, 12, 24 and 48 h. Real-time-QPCR based on TaqMan methodology was applied to analyze quantitatively the transcript levels of these genes. The transcription of β-actin and GAPDH genes was assessed in parallel to select the control gene with least variability. The 2-ΔΔCt method was used to analyze the relative changes in gene transcription. InsP6 stimulated p53 and p21WAF1 expression at the mRNA level, with the highest increase in p21WAF1 mRNA occurring at 24 h, i.e., following the highest increase in p53 mRNA observed at 12 h. Based on these studies it may be concluded that the ability of InsP6 to arrest the cell cycle may be mediated by the transcriptional up-regulation of the p53-responsive p21WAF1 gene

The Influence of Chain Microstructure of Biodegradable Copolyesters Obtained with Low-Toxic Zirconium Initiator to In Vitro Biocompatibility

Because of the wide use of biodegradable materials in tissue engineering, it is necessary to obtain biocompatible polymers with different mechanical and physical properties as well as degradation ratio. Novel co- and terpolymers of various composition and chain microstructure have been developed and applied for cell culture. The aim of this study was to evaluate the adhesion and proliferation of human chondrocytes to four biodegradable copolymers: lactide-coglycolide, lactide-co-ε-caprolactone, lactide-co-trimethylene carbonate, glycolide-co-ε-caprolactone, and one terpolymer glycolide-colactide-co-ε-caprolactone synthesized with the use of zirconium acetylacetonate as a nontoxic initiator. Chain microstructure of the copolymers was analyzed by means of 1H and 13C NMR spectroscopy and surface properties by AFM technique. Cell adhesion and proliferation were determined by CyQUANT Cell Proliferation Assay Kit. After 4 h the chondrocyte adhesion on the surface of studied materials was comparable to standard TCPS. Cell proliferation occurred on all the substrates; however, among the studied polymers poly(L-lactide-coglycolide) 85 : 15 that characterized the most blocky structure best supported cell growth. Chondrocytes retained the cell membrane integrity evaluated by the LDH release assay. As can be summarized from the results of the study, all the studied polymers are well tolerated by the cells that make them appropriate for human chondrocytes growth

Bioactive (Co)oligoesters as Potential Delivery Systems of p-Anisic Acid for Cosmetic Purposes

This article reports the studies on bioactive (co)oligoesters towards their use as controlled delivery systems of p-anisic acid. The objects of the study were oligo[3-hydroxy-3-(4-methoxybenzoyloxymethyl)propionate], (p-AA-CH2-HP)n oligoester, and oligo[(3-hydroxy-3-(4-methoxybenzoyloxymethyl)propionate)-co-(3-hydroxybutyrate)] [(p-AA-CH2-HP)x-co-(HB)y (co)oligoesters containing p-anisic acid moiety (p-AA, as the bioactive end and side groups) connected to the polymer backbone through the susceptible to hydrolysis ester bonds. A thorough insight into the hydrolysis process of the bioactive (co)oligoesters studied has allowed us to determine the release profile of p-AA as well as to identify polymer carrier degradation products. The p-AA release profiles determined on the basis of high-performance liquid chromatography (HPLC) measurements showed that the release of the bioactive compound from the developed (co)oligoester systems was regular and no burst effect occurred. Biological studies demonstrated that studied (homo)- and (co)oligoesters were well tolerated by HaCaT cells because none of them showed notable cytotoxicity. They promoted keratinocyte growth at moderate concentrations. Bioactive (co)oligoesters containing p-anisic acid moiety had somewhat decreased cell proliferation at the highest concentration (100 µg/mL). The important practical inference of the current study is that the (co)oligoesters developed have a relatively large load of the biologically active substance (p-AA) per polymer macromolecule, which unlocks their potential application in the cosmetic industry