High Throughput Study for Molecular Mechanism of Metformin Pre-Diabetic Protection via Microarray Approach.

BACKGROUND: Metformin is a biguanide that exhibits antidiabetic, anticarcinogenic, and anti-inflammatory properties. Despite well-known pancreatic protective effects, metformin's influence on pancreatic islet ß-cell is yet considerably unknown. Protecting the functional insulin-producing ß-cells in the pancreas is a key therapeutic challenge in patients with type 1 (T1DM) or type 2 diabetes mellitus (T2DM). OBJECTIVE: The current study aimed to analyze the protective effects of metformin on streptozocin- induced diabetic rats in T1DM in hepatic tissues. METHODS: In the present study, male Wistar rats (n=24) were randomly assigned into 2 groups (n=12 for each control and test), and metformin (100 mg/kg/day) was given for 7 weeks. Afterward, diabetes was induced by streptozocin (STZ) at a single dose of 150 mg/kg. Blood glucose was examined daily before and after STZ induction. The animals were euthanized by cervical dislocation 5 days after streptozocin injection, after which liver and pancreas were harvested from each rat. RESULTS: The biochemical analyses revealed that metformin resulted in significantly reduced plasma glucose levels and higher pancreatic insulin levels in the test group. Using a restrictive cut-off of at least 2-FC and an adjusted p-value (q-value) of ≤0.05, a sum of 747 genes for the metformin group were shown to be differentially regulated compared to controls (320 Down and 427 Up), by which they were obtained from the liver. Furthermore, the evidence is attained that metformin may hinder the loss of critical ß-cells by reducing inflammatory and apoptosis signaling, promoting fatty acid ß-oxidation, and inducing metabolism. CONCLUSION: Collectively, this study has demonstrated a decrease in blood glucose levels and a rise in insulin-levels and thus consequent prophylactic effects in metformin-given STZ-induced diabetic rats.

The effect of cycling hypoxia on MCF-7 cancer stem cells and the impact of their microenvironment on angiogenesis using human umbilical vein endothelial cells (HUVECs) as a model.

BACKGROUND: Breast cancer is the most common type of cancer among females. Hypoxia mediates cancer hallmarks and results from reduced oxygen level due to irregularities in tumor vascularization or when the tumor size prevents oxygen diffusion and triggers angiogenesis to compensate for low oxygen. Cancer stem cells (CSCs) are a rare subpopulation, able to self-renew and to give rise to tumor-initiating cells. It is proposed that CSCs' secretions help to recruit endothelial cells via angiogenic factors to establish tumor vascularization. In the tumor microenvironment, the effect of hypoxia on CSCs and the impact of their secretions on triggering angiogenesis and tumor vascularization remain questionable. In this study, three-dimensional (3D) CSCs derived from MCF-7 were directly exposed to repetitive long-term cycles of hypoxia to assess its effect on CSCs and then to evaluate the role of the hypoxic CSCs' (CSCsHYP) secretions in angiogenesis using (HUVECs) as a model for tumor neovascularization response. METHODS: CSCs derived from MCF-7 cell-line were expanded under repetitive, strictly optimized, long-term/continuous and intermittent hypoxic shots for almost four months to assess hypoxic effect on CSCs, sorted based on CD44+/CD24- biomarkers. Hypoxic phenotype of CSCsHYP was evaluated by assessing the acquired chemoresistance using MTT assay and elevated stemness properties were assessed by flow cytometry. To evaluate the effect of the secretions from CSCsHYP on angiogenesis, HUVECs were exposed to CSCsHYP conditioned-medium (CdM)-in which CSCs had been previously grown-to mimic the tumor microenvironment and to assess the effect of the secretions from CSCsHYP on the HUVECs' capability of tube formation, migration and wound healing. Additionally, co-culture of CSCsHYP with HUVECs was performed. RESULTS: CSCsHYP acquired higher chemoresistance, increased stemness properties and obtained greater propagation, migration, and wound healing capacities, when compared to CSCs in normoxic condition (CSCsNOR). HUVECs' tube formation and migration abilities were mediated by hypoxic (CSCs) conditioned media (CdM). DISCUSSION: This study demonstrates that chemoresistant and migrational properties of CSCs are enhanced under hypoxia to a certain extent. The microenvironment of CSCsHYP contributes to tumor angiogenesis and migration. Hypoxia is a key player in tumor angiogenesis mediated by CSCs.