Sodium butyrate induced keratinocyte apoptosis

NRAS mutant E132K identified in young-onset sporadic colorectal cancer and the canonical mutants G12D and Q61K affect distinct oncogenic phenotypes

Recent data show a global increase in colorectal cancer (CRC) cases among younger demographics, which portends poorer prognosis. The cause of rising incidence is uncertain, and its mutational landscape remains largely unexplored, including those in genes of the epidermal growth factor receptor pathway. Among these are NRAS mutants where there is paucity of functional studies compared to KRAS. Here, the novel NRAS mutant E132K, identified in three tumor samples from Filipino young-onset, sporadic colorectal cancer patients, was investigated for its effects on different cancer hallmarks, alongside the NRAS canonical mutants G12D and Q61K which are yet poorly characterized in the context of CRC. The novel NRAS mutant E132K and the canonical G12D and Q61K mutants show resistance to apoptosis, cytoskeletal reorganization, and loss of adhesion. In contrast to activating KRAS mutations, including the analogous KRAS G12D and Q61K mutations, all three NRAS mutants have no apparent effect on cell proliferation and motility. The results highlight the need to characterize isoform- and mutation-specific oncogenic phenotypes which can have repercussions in disease management and choice of therapeutic intervention. Further analyses of young-onset versus late-onset CRC datasets are necessary to qualify NRAS E132K as a biomarker for the young-onset subtype.

Functional Role of Probiotics and Prebiotics on Skin Health and Disease

Scientific and commercial interest of probiotics, prebiotics and their effect on human health and disease has increased in the last decade. The aim of this review article is to evaluate the role of pro- and prebiotics on the normal function of healthy skin as well as their role in the prevention and therapy of skin disease. Lactobacilli and Bifidobacterium are the most commonly used probiotics and thought to mediate skin inflammation, treat atopic dermatitis (AD) and prevent allergic contact dermatitis (ACD). Probiotics are shown to decolonise skin pathogens (e.g., P. aeruginosa, S. aureus, A. Vulgaris, etc.) while kefir is also shown to support the immunity of the skin and treat skin pathogens through the production of antimicrobial substances and prebiotics. Finally, prebiotics (e.g., Fructo-oligosaccharides, galacto-oligosaccharides and konjac glucomannan hydrolysates) can contribute to the treatment of diseases including ACD, acne and photo aging primarily by enhancing the growth of probiotics.

The skin microbiome and immune system: Potential target for chemoprevention?

There has been increasing interest in understanding the role of the human microbiome in skin diseases. Microbiome studies are being utilized in skin cancer research in numerous ways. Commensal bacteria are being studied as a potential tool to judge the biggest environmental risk of skin cancer, ultraviolet (UV) radiation. Owing to the recognized link of skin microbes in the process of inflammation, there have been theories linking commensal bacteria to skin cancer. Viral metagenomics has also provided insight into virus linked forms of skin cancers. Speculations can be drawn for skin microbiome that in a manner similar to gut microbiome, they can be involved in chemoprevention of skin cancer. Nonetheless, there are definitely huge gaps in our knowledge of the relationship of microbiome and skin cancers, especially in relation to chemoprevention. The utilization of microbiome in skin cancer research seems to be a promising field and may help yield novel skin cancer prevention and treatment options. This review focuses on recent utilization of the microbiome in skin cancer research, and it explores the potential of utilizing the microbiome in prevention, earlier diagnosis, and treatment of skin cancers.

Combined treatment with sodium butyrate and PD153035 enhances keratinocyte differentiation

Epidermal growth factor (EGF) receptor (EGFR) signalling is a critical determinant of keratinocyte proliferation and differentiation in both normal and diseased skin. Here we explore the effects of combined treatment with the differentiation-promoting agent sodium butyrate (SB) and the EGFR inhibitor (EGFRI) PD153035 on terminal differentiation of normal human epidermal keratinocytes (NHEKs). Cells treated with SB showed increased expression of the levels of mRNA and protein of the differentiation markers filaggrin and transglutaminase 1. Cotreatment with EGF significantly blunted these effects of SB. Combined treatment with SB and PD153035 alleviated these inhibitory actions of EGF, resulting in improved effects of decreased cell growth and increased terminal differentiation, relative to the individual treatments. These results indicate that the combined use of a differentiation-promoting agent and an EGFR inhibitor may offer an additional approach to the management of hyperproliferative skin diseases.

Antigen-specific CD8 T cells can eliminate antigen-bearing keratinocytes with clonogenic potential via an IFN-gamma-dependent mechanism

The immune system surveys the skin for keratinocytes (KCs) infected by viruses or with acquired genetic damage. The mechanism by which T cells mediate KC elimination is however undefined. In this study we show that antigen-specific CD8 T cells can eliminate antigen-bearing KCs in vivo and inhibit their clonogenic potential in vitro, independently of the effector molecules perforin and Fas-ligand (Fas-L). In contrast, IFN-gamma receptor expression on KCs and T cells producing IFN-gamma are each necessary and sufficient for in vitro inhibition of KC clonogenic potential. Thus, antigen-specific cytotoxic T lymphocytes (CTLs) may mediate destruction of epithelium expressing non-self antigen by eliminating KCs with potential for self-renewal through an IFN-gamma-dependent mechanism.

T-lymphocyte-induced, Fas-mediated apoptosis is associated with early keratinocyte differentiation

The development of eczematous lesions is thought to be due in part to a breakdown in skin barrier function as a result of T lymphocytes (T cells) invading the skin causing epidermal keratinocyte apoptosis. In this study, we investigated the interaction of T cells and keratinocytes on apoptosis and terminal differentiation using an in vitro co-culture system. Experiments were performed using the HaCaT keratinocyte cell line or normal human epidermal keratinocytes. Activated human peripheral blood-derived T cells were found to induce Fas-dependent keratinocyte apoptosis by up to sixfold. Increased Fas was associated with increased IFN-gamma. The T-cell apoptotic signal was found to target preferentially keratinocytes in the very early stages of terminal differentiation, such as those with low levels of alpha 6-integrin expression, and result in subsequent increased caspase 3 activity. This observation was accompanied by a marked increase in keratinocyte ICAM-1 expression and its ligand LFA-1 on T cells. Our data suggest that T cells may initiate the onset of keratinocyte terminal differentiation making them more susceptible to Fas-dependent cell death signals delivered by the T cells.

Sodium butyrate induces apoptosis and regulates caspase-3 in colorectal cancer cells COLO205

AIM: To observe the regulatory effects of sodium butyrate on caspase-3 in COLO205 colorectal cancer cells, and to investigate the mechanisms of apoptosis in COLO205 induced by sodium butyrate.

METHODS: 1, 2, 4 mmol/L sodium butyrate were co-cultured with COLO205 cells for 48 h, respectively; the viability of COLO205 was detected using MTT method; the expression of caspase-3, using immunohistochemical method; the rate of apoptosis in COLO205, using flow cytometry.

RESULTS: Compared with negative control group, the viability of COLO205 (0.47 ± 0.09, 0.40 ± 0.03, 0.37 ± 0.02 vs 0.55 ± 0.09, P < 0.05 or 0.01) was lower obviously; sodium butyrate promoted the masculine expression of caspase-3 (31.9 ± 1.15, 40.6 ± 1.04, 51.7 ± 1.17 vs 29.4 ± 1.02, P < 0.05 or 0.01), and elevated the rate of apoptosis (8.27%±0.42%, 15.1% ± 0.72%, 21.6% ± 0.95% vs 7.0% ± 0.33%, P < 0.05 or 0.01) in COLO205.

CONCLUSION: Sodium butyrate induces the apoptosis of COLO205 through enhancing the expression of caspase-3 gene.

Bisindolylmaleimide IX facilitates extrinsic and initiates intrinsic apoptosis in TNF-alpha-resistant human colon adenocarcinoma COLO 205 cells

Human COLO 205 colon adenocarcinoma cells are immune to extrinsic apoptosis induced by immunomodulatory cytokines. Among the antiapoptotic mechanisms responsible for the immune escape, the overexpression of the cFLIP protein seems to be critical. cFLIP appears to inhibit the TNF-alpha-induced death receptor signal. The application of the metabolic inhibitor bisindolylmaleimide IX (Bis-IX), known as a potent PKC repressor, sensitized COLO 205 cells to TNF-alpha-mediated apoptosis. The Western-blot analysis revealed that the susceptibility of human COLO 205 cells to apoptogenic stimuli resulted from time-dependent reduction in cFLIP(L) and TRADD protein levels. At the same time, the level of FADD protein was up-regulated. Additionally, the combined TNF-alpha and Bis-IX treatment caused cleavages of Bid and procaspase-9, as well as cytochrome c release. Thus, the evidence of this study indicates that Bis-IX facilitates the death receptor signal mediated by TNF-R1. Moreover, Bis-IX alone initiated intrinsic apoptosis, which could be abolished by Bcl-2 delivery. It heralds the involvement of mitochondria in caspase-8-independent intrinsic apoptosis. In turn, the treatment with bisindolylmaleimide III (Bis-III) did not assist TNF-alpha-dependent apoptosis.

Marker profiling of normal keratinocytes identifies the stroma from squamous cell carcinoma of the oral cavity as a modulatory microenvironment in co-culture

PURPOSE

The microenvironment established by stromal cells may or may not influence phenotypic aspects of epithelial cells and may be relevant for tumor and stem cell biology. We address this issue for keratinocytes using tumor-derived stromal cells in a co-culture system.

MATERIALS AND METHODS

We isolated stromal cells from human squamous cell carcinoma tissue and studied their effect on phenotypic characteristics of normal human interfollicular keratinocytes in vitro.

RESULTS

Stromal fibroblasts significantly influence immuno- and lectin cytochemical properties of co-cultured normal keratinocytes. Expression of keratins 8 and 19, the nucleolar protein nucleostemin, parameters related to adhesion/growth-regulatory galectins and the epithelial-mesenchymal transition were altered. This biological activity of tumor-derived stromal cells, which did not require cell contact, appeared to be stable, because it was maintained during passaging of keratinocytes in the absence of cancer cells.

CONCLUSIONS

Tumor-derived stromal fibroblasts acquire distinct properties to shape a microenvironment conducive to altering the phenotypic characteristics of normal epithelial cells in vitro.