using-alizarin-red-staining-to-detect-chemically-induced-bone-loss

Using Alizarin Red Staining to Detect Chemically Induced Bone Loss in Zebrafish Larvae

Chemically induced bone loss due to lead (Pb) exposure could trigger an array of adverse impacts on both human and animal skeletal systems. However, the ...

medical college of soochow university

The therapeutic use of silk-derived materials such as fibroin in biomedicine is well-established in Southeast Asian countries. Studies indicated that silk fibroin (SF) peptide enhances insulin sensitivity and glucose metabolism phenomena associated with type 2 diabetes mellitus (T2DM) suggesting this peptide may be beneficial to treat this disease. However, the mechanisms underlying protective effect of SF in insulin-mediated hepatic metabolic dysfunction remains unclear. The aim of this study was to investigate the influence of SF on insulin resistant HepG2 cells which were used a model of T2DM. Treatment of cells with 30 mmol/L of glucose and 10 mol/L insulin for 48 h significantly reduced glucose consumptions and intracellular glycogen levels but increased triglyceride (TG) levels. SF or metformin alone elevated glucose consumptions and glycogen accumulation accompanied by lower TG content. Greater effects in these metabolic parameters were found when SF and metformin were combined. Treatment of insulin resistant cells with SF or metformin alone decreased levels of reactive oxygen species (ROS), malondialdehyde (MDA), tumor necrosis factor (TNF-α) and interleukin-6 (IL-6); whereas antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) activity, as well as total antioxidant capacity (T-AOC) ability increased. The combination of SF and metformin produced greater changes in these parameters compared to metformin alone. Data indicated that the protective effect of SF or metformin in insulin resistant HepG2 cells involves inhibition of oxidant processes and that the combination of agents may prove more effective therapeutically.

The protective effect of silk fibroin on high glucose induced insulin resistance in HepG2 cells.

NF-E2-related factor 2 (Nrf2) plays an important role in tumour proliferation and chemoresistance. Nrf2 expression levels may be associated with prognosis of lung cancer, but previous results have been inconsistent. Pooled hazard ratios (HRs) and odds ratios were calculated to assess the prognostic value of the Nrf2 expression in this meta-analysis. Nine studies with 940 patients were included. A high Nrf2 expression level was significantly related to decreased overall survival (OS) (HR = 1.948, 95% CI = 1.564-2.427), lower response rate (HR = 2.675, 95% CI = 1.553-4.610), and poor progression-free survival (HR = 3.078, 95% CI = 1.791-5.293). Subgroup analysis demonstrated that high-Nrf2-expression was significantly correlated with worse OS of patients possessing epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) or undergoing chemotherapeutic treatments (HR = 2.500, 95% CI = 1.556-4.018). Conversely, this high expression was not significantly related to the OS of patients with surgical resection (HR = 1.750, 95% CI = 0.995-3.080, and =.052). High Nrf2 expression was significantly correlated with worse OS of patients in advanced stage (HR = 2.500, 95% CI = 1.556-4.018), compared with early cancer stage (HR = 1.609, 95% CI = 0.675-3.835, and =.283). This meta-analysis suggests that high Nrf2 expression may be a predictive factor of poor outcomes in lung cancer. Therefore, Nrf2 likely plays an important role in prognostic evaluation and may be a therapeutic target for EGFR-TKIs therapy and chemotherapy.

High NF-E2-related factor 2 expression predicts poor prognosis in patients with lung cancer: a meta-analysis of cohort studies.

Long-term exposure to sodium arsenite was found to induce malignant transformation in human bronchial epithelial (HBE) cell line as evidenced by elevated ROS levels. Although chronic sodium arsenite-induced HBE cell line transformation was associated with elevated ROS generation, it was of interest to determine whether acute sodium arsenite exposure also initiated pulmonary damage. Thus, the aim of this study was to investigate oxidative-stress-related pulmonary damage using a human bronchial epithelial (HBE) cell line. Incubation of ρ-HBE (in the presence of mitochondrial DNA) cells with various concentrations of sodium arsenite, significantly increased ROS and MDA levels accompanied by decreased SOD activity in a concentration-dependent manner. In contrast, treatment of ρHBE (without mitochondrial DNA) cells various concentrations of sodium arsenite a reduction in ROS and MDA levels were noted. However, the SOD activity remained decreased in ρHBE cells. This was accompanied by a significant rise in HO-1 protein expressions levels in both cell types with greater changes ρHBE cells at the lower sodium arsenite concentrations. Data indicate that acute sodium arsenite exposure exerted a greater effect ρHBE cells suggesting that absence of mitochondrial DNA appears to enhance sensitivity to the oxidant actions of inorganic As.

Role of mitochondrial DNA in oxidative damage induced by sodium arsenite in human bronchial epithelial cells.

As a confirmed human carcinogen, arsenic can cause skin cancer, lung cancer, etc. However, its carcinogenic mechanism is still unclear. In recent years, the oxidative stress hypothesis has become widely accepted. In mammals it has been found that arsenic can be converted to dimethylarsinous acid (DMA) and dimethylmonothioarsinic acid (DMMTA) through a series of methylation and redox reactions. DMA and DMMTA are highly toxic.

Possible differences in the mechanism of malignant transformation of HaCaT cells by arsenite and its dimethyl metabolites, particularly dimethylthioarsenics.

Autophagy dysfunction in arsenite toxicity plays critical roles in cancer development and progression. However, the precise mechanisms of arsenite-induced skin cancer by blocking autophagy remain uncertain. Herein, this study investigated molecular mechanisms of arsenite-induced autophagy dysfunction mediated by nuclear factor erythroid-2 related factor 2 (Nrf2) in human keratinocyte (HaCaT) cells. The effects of long-term arsenite exposure on Nrf2 activation and autophagy were established using a siRNA interference assay and western blots. A specific siRNA of Nrf2 was used to verify that autophagy induced by arsenite can be influenced by Nrf2. Specific inhibitors of PI3K (LY294002) and mTOR (Rapamycin) and siRNA of Nrf2 were employed to verify that upregulation of Nrf2 correlated with activating the PI3K/Akt pathway. Downstream mTOR and Bcl2 were upregulated by Nrf2 signaling, inhibiting autophagy initiation in arsenite-exposed HaCaT cells. In conclusion, our data suggest that long-term exposure to arsenite promotes Nrf2 upregulation via the PI3K/Akt pathway and, along with upregulation of downstream mTOR and Bcl2, contributes to autophagy dysfunction in transformed HaCaT cells. This work provides new insights into the mechanisms underlying arsenite-induced autophagy dysfunction in cancer promotion and malignancy progression.

Long-term arsenite exposure decreases autophagy by increased release of Nrf2 in transformed human keratinocytes.

Growth hormone (GH)/insulin-like growth factor (IGF) axis plays a critical role in fetal development. However, the effect of arsenite exposure on the GH/IGF axis and its toxic mechanism are still unclear. Zebrafish embryos were exposed to a range of NaAsO concentrations (0.0-10.0 mM) between 4 and 120 h post-fertilization (hpf). Development indexes of survival, malformation, hatching rate, heart rate, body length and locomotor behavior were measured. Hormone levels, GH/IGF axis-related genes, and nerve-related genes were also tested. The results showed that survival rate, hatching rate, heart rate, body length and locomotor behavior all decreased, while deformity increased. At 120 hpf, the survival rate of zebrafish in 1.5 mM NaAsO group was about 70%, the deformity rate exceeded 20%, and the body length shortened to 3.35 mm, the movement distance of zebrafish decreased approximately 63.6% under light condition and about 52.4% under dark condition. The level of GH increased and those of IGF did not change significantly, while the expression of GH/IGF axis related genes (ghra, ghrb, igf2r, igfbp3, igfbp2a, igfbp5b) and nerve related genes (dlx2, shha, ngn1, elavl3, gfap) decreased. In 1.5 mM NaAsO group, the decrease of igfbp3 and igfbp5b was almost obvious, about 78.2% and 72.2%. The expression of nerve genes in 1.5 mM NaAsO group all have declined by more than 50%. These findings suggested that arsenite exerted disruptive effects on the endocrine system by interfering with the GH/IGF axis, leading to zebrafish embryonic developmental toxicity.

Qianlei Yang

Department of Toxicology,
School of Public Health,
Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases,
Department of Toxicology, School of Public Health, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases

medical college of soochow university

Using Alizarin Red Staining to Detect Chemically Induced Bone Loss in Zebrafish Larvae