Obesity Associated with Prediabetes Increases the Risk of Breast Cancer Development and Progression-A Study on an Obese Rat Model with Impaired Glucose Tolerance.

Patients with comorbidities of obesity and diabetes are recognized to be at high risk of breast cancer development and face worse breast cancer outcomes. Though several reports showed the reinforced link between obesity, diabetes, and prediabetes with breast cancer, the underlying molecular mechanisms are still unknown. The present study aimed to investigate the underlying molecular link between increased risks of breast cancer due to coincident diabetes or obesity using a spontaneous obese rat model with impaired glucose tolerance (WNIN/GR-Ob rat). A single dose of solubilized DMBA suspension (40 mg/kg body weight) was orally administered to the animals at the age of 60 days to induce breast tumors. The tumor incidence, latency period, tumor frequency, and tumor volume were measured. Histology, immunohistochemistry, and immunoblotting were performed to evaluate the tumor morphology and expression levels of signal molecules. The development of mammary tumors in GR-Ob rats was characterized by early onset and shorter latency periods compared to control lean rats. While 62% of obese rats developed breast tumors, tumor development in lean rats was only 21%. Overexpression of ER, PR, Ki67, and p53 markers was observed in tumor tissues of obese rats in comparison with lean rats. The levels of the hallmarks of cell proliferation and angiogenesis involved in IGF-1/PI3K/Akt/GSK3ß/ß-catenin signaling pathway molecules were upregulated in obese rat breast tumors compared to lean rats. Furthermore, obesity with prediabetes is associated with changes in IGF-1 signaling and acts on PI3K/Akt/GSK3ß/ß-catenin signaling, which results in rapid cell proliferation and development of breast tumors in obese rats than the lean rats. These results indicate that tumor onset and development were faster in spontaneous obese rat models with impaired glucose tolerance than in their lean counterparts.

Mustard gas exposure instigates retinal Müller cell gliosis.

Sulfur mustard (SM) is a chemical warfare agent (CWA) that causes severe eye pain, photophobia, excessive lacrimation, corneal and ocular surface defects, and blindness. However, SM's effects on retinal cells are relatively meager. This study investigated the role of SM toxicity on Müller glial cells responsible for cellular architecture, inner blood-retinal barrier maintenance, neurotransmitter recycling, neuronal survival, and retinal homeostasis. Müller glial cells (MIO-M1) were exposed to SM analog, nitrogen mustard (NM), at varying concentrations (50-500 µM) for 3 h, 24 h, and 72 h. Müller cell gliosis was evaluated using morphological, cellular, and biochemical methods. Real-time cellular integrity and morphological evaluation were performed using the xCELLigence real-time monitoring system. Cellular viability and toxicity were measured using TUNEL and PrestoBlue assays. Müller glia hyperactivity was calculated based on glial fibrillary acidic protein (GFAP) and vimentin immunostaining. Intracellular oxidative stress was measured using DCFDA and DHE cell-based assays. Inflammatory markers and antioxidant enzyme levels were determined by quantitative real-time PCR (qRT-PCR). AO/Br and DAPI staining further evaluated DNA damage, apoptosis, necrosis, and cell death. Inflammasome-associated Caspase-1, ASC, and NLRP3 were studied to identify mechanistic insights into NM toxicity in Müller glial cells. The cellular and morphological evaluation revealed the Müller glia hyperactivity after NM exposure in a dose- and time-dependent manner. NM exposure caused significant oxidative stress and enhanced cell death at 72 h. A significant increase in antioxidant indices was observed at the lower concentrations of NM. Mechanistically, we found that NM-treated MIO-M1 cells increased caspase-1 levels that activated NLRP3 inflammasome-induced production of IL-1ß and IL-18, and elevated Gasdermin D (GSDMD) expression, a crucial component actuating pyroptosis. In conclusion, NM-induced Müller cell gliosis via increased oxidative stress results in caspase-1-dependent activation of the NLRP3 inflammasome and cell death driven primarily by pyroptosis.

Dietary zinc deficiency disrupts skeletal muscle proteostasis and mitochondrial biology in rats.

OBJECTIVES: Zinc deficiency is related to reduced growth, mass, and work capacity of skeletal muscle. However, the underlying mechanisms in connection with skeletal muscle proteostasis and mitochondrial biology are not clear. The aim of this study was to investigate the consequences of dietary zinc deficiency on skeletal muscle proteostasis and mitochondrial biology in growing rats. METHODS: Three-wk-old male Wistar/Kyoto weanling rats were fed either a zinc-deficient diet (<1 mg/kg; ad libitum) or a control diet pair-fed with zinc-deficient group (47.5 mg/kg) for a 7-wk period. Skeletal (gastrocnemius) muscle myofiber cross-sectional area was measured on hematoxylin and eosin-stained sections. Real-time quantitative reverse transcription polymerase chain reaction and immunoblotting were performed to study the target gene and protein expression, respectively. The chymotrypsin-like proteasomal activity was analyzed by fluorescence method. RESULTS: Results showed a decreased mean muscle fiber cross-sectional area and increased apoptosis in the muscle of zinc-deficient rats. Activation of the ubiquitin-proteasome system as indicated by increased levels of the E1 enzyme, MuRF1 (muscle-specific E3 ligase; muscle atrophy marker) and proteasomal activity was observed in the zinc-deficient rats. Declined autophagy (Beclin1, ATG5, and LC3), and increased endoplasmic reticulum stress markers were observed. Zinc deficiency also affected mitochondrial biology including fission, fusion, transcription, and oxidative phosphorylation components. CONCLUSION: Zinc deficiency disturbed the skeletal muscle proteostasis, and mitochondrial biology, causing decreased cell size and increased cell death.