Selenophosphate synthetase 1 deficiency exacerbates osteoarthritis by dysregulating redox homeostasis.

Aging and mechanical overload are prominent risk factors for osteoarthritis (OA), which lead to an imbalance in redox homeostasis. The resulting state of oxidative stress drives the pathological transition of chondrocytes during OA development. However, the specific molecular pathways involved in disrupting chondrocyte redox homeostasis remain unclear. Here, we show that selenophosphate synthetase 1 (SEPHS1) expression is downregulated in human and mouse OA cartilage. SEPHS1 downregulation impairs the cellular capacity to synthesize a class of selenoproteins with oxidoreductase functions in chondrocytes, thereby elevating the level of reactive oxygen species (ROS) and facilitating chondrocyte senescence. Cartilage-specific Sephs1 knockout in adult mice causes aging-associated OA, and augments post-traumatic OA, which is rescued by supplementation of N-acetylcysteine (NAC). Selenium-deficient feeding and Sephs1 knockout have synergistic effects in exacerbating OA pathogenesis in mice. Therefore, we propose that SEPHS1 is an essential regulator of selenium metabolism and redox homeostasis, and its dysregulation governs the progression of OA.

Influence of Irradiation on Capsules of Silicone Implants Covered with Acellular Dermal Matrix in Mice.

BACKGROUND: In advanced breast cancer, radiotherapy is recommended as adjuvant therapy following breast reconstructive surgery. This inevitably led to growing concerns over possible complications of radiotherapy on implants. In this experimental animal study, we investigated the utility of acellular dermal matrix (ADM) wraps around implants as preventive management for radiotherapy complications. METHODS: Black mice (C57NL6; n = 32) were assigned to groups that either received radiation or did not: groups A and B underwent surgery using implants without radiotherapy; while groups C and D underwent surgery using implants with radiotherapy for one and three months, respectively. The hemispheric silicone implants with an 0.8-cm-diameter were inserted on the left back of each mouse, and implants wrapped by ADM were inserted on the right back. The Clinic 23EX LINAC model was used for irradiation at 10 Gy. The samples were evaluated by gross assessment, histological analysis, immunohistochemical analysis, and the Western blotting test. RESULTS: The H&E staining analysis showed that membrane thickness is smallest in group A, followed by groups C, D, and B. In a Masson trichrome histological analysis, collagen fibers became less dense and more widespread over time in the groups that received an ADM. Immunohistochemistry findings were similarly constant. However, the expression of TGF-ß1 was increased in the irradiated groups, whereas it was decreased in the non-irradiated groups as observed over time. CONCLUSIONS: Radiotherapy was shown to increase risk factors for capsular contracture, including inflammatory response, pseudoepithelium, thinning of membrane, and TGF-ß1 expression over time; however, the accompanying framework using an ADM as a barrier between implant and tissue was shown to be effective in alleviating these risks. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The role of selenium metabolism and selenoproteins in cartilage homeostasis and arthropathies.

As an essential nutrient and trace element, selenium is required for living organisms and its beneficial roles in human health have been well recognized. The role of selenium is mainly played through selenoproteins synthesized by the selenium metabolic system. Selenoproteins have a wide range of cellular functions including regulation of selenium transport, thyroid hormones, immunity, and redox homeostasis. Selenium deficiency contributes to various diseases, such as cardiovascular disease, cancer, liver disease, and arthropathy-Kashin-Beck disease (KBD) and osteoarthritis (OA). A skeletal developmental disorder, KBD has been reported in low-selenium areas of China, North Korea, and the Siberian region of Russia, and can be alleviated by selenium supplementation. OA, the most common form of arthritis, is a degenerative disease caused by an imbalance in matrix metabolism and is characterized by cartilage destruction. Oxidative stress serves as a major cause of the initiation of OA pathogenesis. Selenium deficiency and dysregulation of selenoproteins are associated with impairments to redox homeostasis in cartilage. We review the recently explored roles of selenium metabolism and selenoproteins in cartilage with an emphasis on two arthropathies, KBD and OA. Moreover, we discuss the potential of therapeutic strategies targeting the biological functions of selenium and selenoproteins for OA treatment.

Effect of High-dose Vitamin C Combined With Anti-cancer Treatment on Breast Cancer Cells.

BACKGROUND/AIM: The anti-cancer effect of high doses of intravenous vitamin C (high-dose vitamin C) remains controversial despite growing evidence that high-dose vitamin C exerts anti-tumorigenic activity by increasing the amount of reactive oxygen species in cancer cells without meaningful toxicities. Therefore, this study attempted to demonstrate the in vitro anti-cancer activity of high-dose vitamin C in combination with conventional treatment in breast cancer. MATERIALS AND METHODS: The pro-apoptotic effects of high-dose vitamin C (1.25 to 20 mM) with or without anti-cancer agents (eribulin mesylate, tamoxifen, fulvestrant, or trastuzumab) were estimated using an MTT assay to measure the cell viability of a variety of breast cancer cell lines (MCF7, SK-BR3, and MDA-MB-231), as well as normal breast epithelial cells (MCF10A). RESULTS: High-dose vitamin C (≥10 mM) significantly decreased cell viability of all breast cancer cell lines, particularly of MCF-7 cells. The catalase activities of MCF7 and MDA-MD-231 cells were also lower than those of MCF10A cells. Moreover, cell viability of both MCF7 and MDA-MD-231 cells was decreased further when combining high-dose vitamin C and eribulin mesylate, and this was also true for MCF-7 cells when combining high-dose vitamin C with tamoxifen or fulvestrant and for SK-BR3 cells when combining high-dose vitamin C with trastuzumab in comparison with chemotherapy or endocrine therapy alone. CONCLUSION: Combining high-dose vitamin C with conventional anti-cancer drugs can have therapeutic advantages against breast cancer cells.