Living in aerobic conditions carries a risk of oxidative stress, in connection with free radical deleterious action on tissues and cells. Free radical mechanisms have been implicated in the pathogenesis of many diseases, as well as in host defense against various invading microorganisms. A substantial body of evidence has been reported on free radical involvement in inflammation, ischaemia/reperfusion injury, atherosclerosis and many other pathologies. The aim of this paper is to review selected literature and opinions concerning free radical-induced damage to tissues and to present xenobiotic contribution to oxidative stress.
A new diterpene glucoside (1), named sylviside, was isolated from the aerial parts of Gnaphalium sylvaticum. Its structure was elucidated as 2β,15α,20α-trihydroxy-19,20-dicarboxy-ent-kaur-16-ene 2β-O-(2'-angelate)-β-d-glucopyranoside, on the basis of spectroscopic analysis (1H NMR, 13C NMR, HMQC, HMBC, NOESY), and was confirmed by X-ray crystallographic analysis. Sylviside (1) displayed weak cytotoxicity against HeLa WT (human epitheloid cervical carcinoma) cells and was also evaluated for its effects on reversing multidrug resistance in HeLa cells overexpressing MDR1.
Phytosterols have been proposed to act as potent anticancer agents. However the mechanism of their action has not been elucidated yet. Thus, the aim of our study was to determine whether plant sterols and their thermal processing products (in physiological concentration range) could influence the viability of cancer cells and thus could be considered as positive diet complements. Additionally we decided to study potential specificity of those natural compounds against cells showing high multidrug resistance. In this study we show that the cytotoxic effect of β-sitosterol was observed in both, estrogen-dependent and estrogen-independent cells. It was also shown that the β-sitosterol was significantly more cytotoxic in cells with basal ABCB1 expression (MCF7) than in multidrug resistant NCI/ADR-RES. Surprisingly, 5a,6aepoxysitosterol did not decrease the viability of any investigated cells but on the contrary, it provoked their increased proliferation. It was shown that oxyphytosterols blocked the cell cycle of MCF7 cells in G0/G1 phase while did not affect NCI/ADR-RES cell cycle in physiological concentration range. We also show that PgP activity (responsible for Multidrug Resistance phenomena) is inhibited by β-sitosterol. Thus, the phytosterols are supposed to act at various mechanisms but, what is most interesting, can target cells showing high multidrug resistance potential. Keywords: ABCB1, beta-sitosterol, cancer, PgP, phytosterols, Multidrug Resistant Cancer Cells, anticancer agents, multidrug resistance, sitosterol, ABCB1 expression, oxyphytosterols, PgP activity, P-glycoprotein, ATP-binding cas-sette, estrogen, cardiovascular disease, sphingomyelin cy-cle, caspases, signal-transduction pathways, apoptosis, Liver cells, oxyphytosterols mixture, POLARIS Q mass spectrometer, Cell Culture, Cytotoxicity Assay, RPMI1640, DMEM medium, IC50 values, Propidium Iodide Staining, RNAse, flow cytometry, breast cancer cells, Verapamil, UV light microscopy, Student's t-test, MCF7 cells, MTT test, Colchicine, propidium iodide analysis, camptothecin, real-time PCR analysis, Rhodamine123, Caco-2, HepG2, MCF7, superoxide dismutase, glutathione peroxidase, mitochondrial enzymes activity, human stomach cancer cells
T helper 17 (Th17) cells have crucial functions in mucosal immunity and the pathogenesis of several chronic inflammatory diseases. The lineage-specific transcription factor, RORγt, encoded by the RORC gene modulates Th17 polarization and function, as well as thymocyte development. Here we define several regulatory elements at the human RORC locus in thymocytes and peripheral CD4+ T lymphocytes, with CRISPR/Cas9-guided deletion of these genomic segments supporting their role in RORγt expression. Mechanistically, T cell receptor stimulation induces cyclosporine A-sensitive histone modifications and P300/CBP acetylase recruitment at these elements in activated CD4+ T cells. Meanwhile, NFAT proteins bind to these regulatory elements and activate RORγt transcription in cooperation with NF-kB. Our data thus demonstrate that NFAT specifically regulate RORγt expression by binding to the RORC locus and promoting its permissive conformation.
Cyclic pyrazoles exhibit cytotoxicity to human cancer cells through apoptosis induction. We investigated the proapoptotic activities of two novel synthetic pyrazoles: 5-(p-toluenesulfonyl)pyrazolo[4,3-f]quinoline (tospyrquin) and 5-chloro-3-(p-toluenesulfonyl)indazole (tosind) in HT29 colon cancer cells which are characterised by point mutation (G/A in codon 273) in the p53 gene, which causes the lack of functionality of the p53 protein. Cell viability was evaluated in the MTT assay, cell morphology was assessed by DAPI staining, flow cytometry was used to study the cell cycle, Western blot techniques were applied for measurements of the Bax, Bcl-2, caspase-8, caspase-9 and PARP-1 proteins and DNA damage was evaluated in the Comet assay. Tospyrquin or tosind in a concentration range of 2.5 μM-15 μM caused an approximately 20% diminishment in cell growth, but in higher concentrations (25-100 μM) the observed effect depended on the pyrazole structure and time of treatment. In cell cycle analysis, tosind caused 23.7% of apoptotic death and tospyrquin - 14.9%. These data were supported by an increased level of the pro-apoptotic protein Bax, a decreased level of the anti-apoptotic Bcl-2 and enhanced caspase-8, caspase-9, PARP-1 cleavage. DNA damage was dose-dependent for both tested compounds. The results suggest that the pro-apoptotic activity of tospyrquin and tosind is probably regulated by the extrinsic and the intrinsic pathways.
