Matrix-mediated regulation of type 1 collagen synthesis and degradation in cultured fibroblasts

Includes abstract.Includes bibliographical references (leaves 122-157).Stromal cells and the extracellular matrix (ECM) components provide the microenvironment that is pivotal for cell growth, motility, attachment and differentiation. Fibroblasts are some of the cells responsible for the synthesis of most of the extracellular matrix proteins. Type I collagen is the most abundant extracellular matrix protein in the human body and is found in tissues requiring high tensile strength. In this study we investigated the effect of a pre-formed fibroblast-derived extracellular matrix on the expression of type I collagen and associated matrix metalloproteinases in fibroblasts

Wharton’s jelly-derived mesenchymal stromal cells and fibroblast-derived extracellular matrix synergistically activate apoptosis in a p21-dependent mechanism in WHCO1 and MDA MB 231 cancer cells in vitro

The tumour microenvironment plays a crucial role in tumour progression and comprises tumour stroma which is made up of different cell types and the extracellular matrix (ECM).Mesenchymal stromal cells (MSCs) are part of the tumour stroma and may have conflicting effects on tumour growth. In this study we investigated the effect of Wharton’s Jelly-derived MSCs (WJ-MSCs) and a fibroblast-derived ECM (fd-ECM) on esophageal (WHCO1) and breast (MDAMB 231) cancer cells in vitro. BothWJ-MSCs and the fd-ECM, alone or in combination, downregulate PCNA, cyclin D1, Bcl-2, Bcl-xL, and MMPs and upregulate p53 and p21. p21 induction resulted in G2 phase cell cycle arrest and induced apoptosis in vitro. Our data suggest that p21 induction is via p53- dependent and p53-independent mechanisms inWHCO1 andMDA MB 231 cells, respectively. Vascular endothelial growth factor, Akt, and Nodal pathways were downregulated in cancer cells cocultured with WJ-MSCs. We also demonstrate that WJ-MSCs effects on cancer cells appear to be short-lived whilst the fd-ECM effect is long-lived. This study shows the influence of tumour microenvironment on cancer cell behaviour and provides alternative therapeutic targets for potential regulation of tumour cells.The International Centre for Genetic Engineering and Biotechnology (ICGEB), the South African Medical Research Council, the National Research Foundation (NRF) of South Africa, theUniversity of Pretoria, and the University of Cape Town. Karlien Kallmeyer and Michael S. Pepper’s work was funded by the South African Medical Research Council (University Flagship award and Extramural Stem Cell Unit).http://www.hindawi.com/journals/sci/am2016Immunolog

The garlic compound ajoene covalently binds vimentin, disrupts the vimentin network and exerts anti-metastatic activity in cancer cells

Background Garlic has been used for centuries for its flavour and health promoting properties that include protection against cancer. The vinyl disulfide-sulfoxide ajoene is one of the phytochemicals found in crushed cloves, hypothesised to act by S-thiolating reactive cysteines in target proteins. Methods Using our fluorescently labelled ajoene analogue called dansyl-ajoene, ajoene’s protein targets in MDA-MB-231 breast cancer cells were tagged and separated by 2D electrophoresis. A predominant band was identified by MALDI-TOF MS/MS to be vimentin. Target validation experiments were performed using pure recombinant vimentin protein. Computational modelling of vimentin bound to ajoene was performed using Schrödinger and pKa calculations by Epik software. Cytotoxicity of ajoene in MDA-MB-231 and HeLa cells was measured by the MTT assay. The vimentin filament network was visualised in ajoene-treated and non-treated cells by immunofluorescence and vimentin protein expression was determined by immunoblot. The invasion and migration activity was measured by wound healing and transwell assays using wildtype cells and cells in which the vimentin protein had been transiently knocked down by siRNA or overexpressed. Results The dominant protein tagged by dansyl-ajoene was identified to be the 57 kDa protein vimentin. The vimentin target was validated to reveal that ajoene and dansyl-ajoene covalently bind to recombinant vimentin via a disulfide linkage at Cys-328. Computational modelling showed Cys-328 to be exposed at the termini of the vimentin tetramer. Treatment of MDA-MB-231 or HeLa cells with a non-cytotoxic concentration of ajoene caused the vimentin filament network to condense; and to increase vimentin protein expression. Ajoene inhibited the invasion and migration of both cancer cell lines which was found to be dependent on the presence of vimentin. Vimentin overexpression caused cells to become more migratory, an effect that was completely rescued by ajoene. Conclusions The garlic-derived phytochemical ajoene targets and covalently modifies vimentin in cancer cells by S-thiolating Cys-328. This interaction results in the disruption of the vimentin filament network and contributes to the anti-metastatic activity of ajoene in cancer cells

Addiction in the Light of African Values: Undermining Vitality and Community

In this article I address the question of what makes addiction morally problematic, and seek to answer it by drawing on values salient in the sub-Saharan African philosophical tradition. Specifically, I appeal to life-force and communal relationship, each of which African philosophers have at times advanced as a foundational value, and spell out how addiction, or at least salient instances of it, could be viewed as unethical for flouting them. I do not seek to defend either vitality or community as the best explanation of when and why addiction is immoral, instead arguing that each of these characteristically African values grounds an independent and plausible account of that. I conclude that both vitalism and communalism merit consideration as rivals to accounts that Western ethicists would typically make, according to which addiction is immoral insofar as it degrades rationality or autonomy, as per Kantianism, or causes pain or dissatisfaction, à la utilitarianism

Effect of selenium on cadmium-induced oxidative stress and esterase activity in rat organs

Metal toxicity is a threat mainly in the industrialised world where industry discharges many toxic metals into the environment. We investigated the effects of two metals - cadmium and selenium - on the cytosolic antioxidant enzymes and esterases in the liver, kidneys and testes of rats. Male Sprague-Dawley rats( N =28) were divided equally into four groups: control, cadmium, selenium and cadmium/selenium. Salts of the metals were administered intraperitoneally for 15 days. In the liver, cadmium treatment (1.67 mg/kg per day) resulted in a decrease in catalase activity and an increase superoxide dismutase (SOD) activity. Selenium treatment (0.23 mg/kg per day) resulted in increases in glutathione s-transferase, catalase and DT-diaphorase activities. Treatment with both cadmium and selenium resulted in an increase in glutathione peroxidase (GPx) activity. Esterase activities were significantly lower in the presence of cadmium. In the kidney, cadmium treatment caused a decrease in catalase, DT-diaphorase, and SOD activities and selenium supplementation reversed the cadmium-induced decrease in these enzyme activities. Selenium treatment increased catalase and SOD activities in the kidney. In the testis, cadmium treatment decreased GPx and SOD activities, but at the same time increased catalase and DT-diaphorase activities. Esterase activities increased in the presence of selenium in both the kidney and testis. These results suggest that selenium might be toxic to the liver while at the same time play a protective role against cadmium-induced oxidative stress and toxicity in the kidney and testis

Advances in Therapeutic Targeting of Cancer Stem Cells within the Tumor Microenvironment: An Updated Review

Despite great strides being achieved in improving cancer patients’ outcomes through better therapies and combinatorial treatment, several hurdles still remain due to therapy resistance, cancer recurrence and metastasis. Drug resistance culminating in relapse continues to be associated with fatal disease. The cancer stem cell theory posits that tumors are driven by specialized cancer cells called cancer stem cells (CSCs). CSCs are a subpopulation of cancer cells known to be resistant to therapy and cause metastasis. Whilst the debate on whether CSCs are the origins of the primary tumor rages on, CSCs have been further characterized in many cancers with data illustrating that CSCs display great abilities to self-renew, resist therapies due to enhanced epithelial to mesenchymal (EMT) properties, enhanced expression of ATP-binding cassette (ABC) membrane transporters, activation of several survival signaling pathways and increased immune evasion as well as DNA repair mechanisms. CSCs also display great heterogeneity with the consequential lack of specific CSC markers presenting a great challenge to their targeting. In this updated review we revisit CSCs within the tumor microenvironment (TME) and present novel treatment strategies targeting CSCs. These promising strategies include targeting CSCs-specific properties using small molecule inhibitors, immunotherapy, microRNA mediated inhibitors, epigenetic methods as well as targeting CSC niche-microenvironmental factors and differentiation. Lastly, we present recent clinical trials undertaken to try to turn the tide against cancer by targeting CSC-associated drug resistance and metastasis

Recent Trends in Decellularized Extracellular Matrix Bioinks for 3D Printing: An Updated Review

The promise of regenerative medicine and tissue engineering is founded on the ability to regenerate diseased or damaged tissues and organs into functional tissues and organs or the creation of new tissues and organs altogether. In theory, damaged and diseased tissues and organs can be regenerated or created using different configurations and combinations of extracellular matrix (ECM), cells, and inductive biomolecules. Regenerative medicine and tissue engineering can allow the improvement of patients’ quality of life through availing novel treatment options. The coupling of regenerative medicine and tissue engineering with 3D printing, big data, and computational algorithms is revolutionizing the treatment of patients in a huge way. 3D bioprinting allows the proper placement of cells and ECMs, allowing the recapitulation of native microenvironments of tissues and organs. 3D bioprinting utilizes different bioinks made up of different formulations of ECM/biomaterials, biomolecules, and even cells. The choice of the bioink used during 3D bioprinting is very important as properties such as printability, compatibility, and physical strength influence the final construct printed. The extracellular matrix (ECM) provides both physical and mechanical microenvironment needed by cells to survive and proliferate. Decellularized ECM bioink contains biochemical cues from the original native ECM and also the right proportions of ECM proteins. Different techniques and characterization methods are used to derive bioinks from several tissues and organs and to evaluate their quality. This review discusses the uses of decellularized ECM bioinks and argues that they represent the most biomimetic bioinks available. In addition, we briefly discuss some polymer-based bioinks utilized in 3D bioprinting

Characterization of polyphenols in leaves of four desiccation tolerant plant families

Includes bibliographical references.Polyphenols in plants are known to act as antioxidants, antimicrobials, antifungal, photoreceptors, visual attractors and as light screens. In this study polyphenols in angiosperms found in southern Africa and called resurrection (desiccation tolerant) plants were studied. These plants are Myrothamnus flabellifolius, Xerophyta viscosa, Xerophyta humilis, Xerophyta schlecterii, Xerophyta villosa. Craterostigma wilmsii, Craterostigma plantagineum, Craterostigma pumilum and Eragrostis nindensis. These plants are able to tolerate water stress without undergoing permanent damage. During drying these plants are subjected to different stresses and one such stress is oxidative stress. It has been suggested that polyphenols function as stress protectants in plant cells by scavenging reactive oxygen species (ROS) produced during a period of oxidative stress. In this study the total phenolic content and the related antioxidant capacity of the plants leaf extracts were analysed

Effect of selenium on cadmium-induced oxidative stress and esterase activity in rat organs

Metal toxicity is a threat mainly in the industrialised world where industry discharges many toxic metals into the environment. We investigated the effects of two metals – cadmium and selenium – on the cytosolic antioxidant enzymes and esterases in the liver, kidneys and testes of rats. Male Sprague-Dawley rats (n=28) were divided equally into four groups: control, cadmium, selenium and cadmium/selenium. Salts of the metals were administered intraperitoneally for 15 days. In the liver, cadmium treatment (1.67 mg/kg per day) resulted in a decrease in catalase activity and an increase superoxide dismutase (SOD) activity. Selenium treatment (0.23 mg/kg per day) resulted in increases in glutathione s-transferase, catalase and DT-diaphorase activities. Treatment with both cadmium and selenium resulted in an increase in glutathione peroxidase (GPx) activity. Esterase activities were significantly lower in the presence of cadmium. In the kidney, cadmium treatment caused a decrease in catalase, DT-diaphorase, and SOD activities and selenium supplementation reversed the cadmium-induced decrease in these enzyme activities. Selenium treatment increased catalase and SOD activities in the kidney. In the testis, cadmium treatment decreased GPx and SOD activities, but at the same time increased catalase and DT-diaphorase activities. Esterase activities increased in the presence of selenium in both the kidney and testis. These results suggest that selenium might be toxic to the liver while at the same time play a protective role against cadmium-induced oxidative stress and toxicity in the kidney and testis

The Tumor Microenvironment in Tumorigenesis and Therapy Resistance Revisited

Tumorigenesis is a complex and dynamic process involving cell-cell and cell-extracellular matrix (ECM) interactions that allow tumor cell growth, drug resistance and metastasis. This review provides an updated summary of the role played by the tumor microenvironment (TME) components and hypoxia in tumorigenesis, and highlight various ways through which tumor cells reprogram normal cells into phenotypes that are pro-tumorigenic, including cancer associated- fibroblasts, -macrophages and -endothelial cells. Tumor cells secrete numerous factors leading to the transformation of a previously anti-tumorigenic environment into a pro-tumorigenic environment. Once formed, solid tumors continue to interact with various stromal cells, including local and infiltrating fibroblasts, macrophages, mesenchymal stem cells, endothelial cells, pericytes, and secreted factors and the ECM within the tumor microenvironment (TME). The TME is key to tumorigenesis, drug response and treatment outcome. Importantly, stromal cells and secreted factors can initially be anti-tumorigenic, but over time promote tumorigenesis and induce therapy resistance. To counter hypoxia, increased angiogenesis leads to the formation of new vascular networks in order to actively promote and sustain tumor growth via the supply of oxygen and nutrients, whilst removing metabolic waste. Angiogenic vascular network formation aid in tumor cell metastatic dissemination. Successful tumor treatment and novel drug development require the identification and therapeutic targeting of pro-tumorigenic components of the TME including cancer-associated- fibroblasts (CAFs) and -macrophages (CAMs), hypoxia, blocking ECM-receptor interactions, in addition to the targeting of tumor cells. The reprogramming of stromal cells and the immune response to be anti-tumorigenic is key to therapeutic success. Lastly, this review highlights potential TME- and hypoxia-centered therapies under investigation