"MiR-7 controls cholesterol biosynthesis through posttranscriptional regulation of DHCR24 expression".

Dysregulation of cholesterol homeostasis is associated with several pathologies including cardiovascular diseases and neurological disorders such as Alzheimer's disease (AD). MicroRNAs (miRNAs) have emerged as key post-transcriptional regulators of cholesterol metabolism. We previously established the role of miR-7 in regulating insulin resistance and amyloidosis, which represents a common pathological feature between type 2 diabetes and AD. We show here an additional metabolic function of miR-7 in cholesterol biosynthesis. We found that miR-7 blocks the last steps of the cholesterol biosynthetic pathway in vitro by targeting relevant genes including DHCR24 and SC5D posttranscriptionally. Intracranial infusion of miR-7 on an adeno-associated viral vector reduced the expression of DHCR24 in the brain of wild-type mice, supporting in vivo miR-7 targeting. We also found that cholesterol regulates endogenous levels of miR-7 in vitro, correlating with transcriptional regulation through SREBP2 binding to its promoter region. In parallel to SREBP2 inhibition, the levels of miR-7 and hnRNPK (the host gene of miR-7) were concomitantly reduced in brain in a mouse model of Niemann Pick type C1 disease and in murine fatty liver, which are both characterized by intracellular cholesterol accumulation. Taken together, the results establish a novel regulatory feedback loop by which miR-7 modulates cholesterol homeostasis at the posttranscriptional level, an effect that could be exploited for therapeutic interventions against prevalent human diseases.

Role of miR-199a-5p in the post-transcriptional regulation of ABCA1 in response to hypoxia in peritoneal macrophages.

Hypoxia is a crucial factor contributing to maintenance of atherosclerotic lesions. The ability of ABCA1 to stimulate the efflux of cholesterol from cells in the periphery, particularly foam cells in atherosclerotic plaques, is an important anti-atherosclerotic mechanism. The posttranscriptional regulation by miRNAs represents a key regulatory mechanism of a number of signaling pathways involved in atherosclerosis. Previously, miR-199a-5p has been shown to be implicated in the endocytic and retrograde intracellular transport. Although the regulation of miR-199a-5p and ABCA1 by hypoxia has been already reported independently, the role of miR-199a-5p in macrophages and its possible role in atherogenic processes such us regulation of lipid homeostasis through ABCA1 has not been yet investigated. Here, we demonstrate that both ABCA1 and miR-199a-5p show an inverse regulation by hypoxia and Ac-LDL in primary macrophages. Moreover, we demonstrated that miR-199a-5p regulates ABCA1 mRNA and protein levels by directly binding to its 3'UTR. As a result, manipulation of cellular miR-199a-5p levels alters ABCA1 expression and cholesterol efflux in primary mouse macrophages. Taken together, these results indicate that the correlation between ABCA1-miR-199a-5p could be exploited to control macrophage cholesterol efflux during the onset of atherosclerosis, where cholesterol alterations and hypoxia play a pathogenic role.

New Insights on the Regulation of the Insulin-Degrading Enzyme: Role of microRNAs and RBPs.

The evident implication of the insulin-degrading enzyme (IDE) in Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM), among its capacity to degrade insulin and amyloid-ß peptide (Aß), suggests that IDE could be an essential link in the relation between hyperinsulinemia, insulin resistance and AD. However, little is known about the cellular and molecular regulation of IDE expression, and even less has been explored regarding the post-transcriptional regulation of IDE, although it represents a great molecular target of interest for therapeutic treatments. We recently described that miR-7, a novel candidate for linking AD and T2DM at the molecular level, regulates IDE and other key genes in both pathologies, including some key genes involved in the insulin signaling pathway. Here, we explored whether other miRNAs as well as other post-transcriptional regulators, such as RNA binding proteins (RBP), could potentially participate in the regulation of IDE expression in vitro. Our data showed that in addition to miR-7, miR-125, miR-490 and miR-199 regulate IDE expression at the post-transcriptional level. Moreover, we also found that IDE contains multiple potential binding sites for several RBPs, and a narrow-down prediction analysis led us to speculate on a novel regulation of IDE by RALY and HuD. Taken together, these results demonstrate the novel players controlling IDE expression that could represent potential therapeutical targets to treat several metabolic diseases with a high impact on human health, including AD and T2DM.

Posttranscriptional Regulation of Insulin Resistance: Implications for Metabolic Diseases.

Insulin resistance defines an impairment in the biologic response to insulin action in target tissues, primarily the liver, muscle, adipose tissue, and brain. Insulin resistance affects physiology in many ways, causing hyperglycemia, hypertension, dyslipidemia, visceral adiposity, hyperinsulinemia, elevated inflammatory markers, and endothelial dysfunction, and its persistence leads to the development metabolic disease, including diabetes, obesity, cardiovascular disease, or nonalcoholic fatty liver disease (NAFLD), as well as neurological disorders such as Alzheimer's disease. In addition to classical transcriptional factors, posttranscriptional control of gene expression exerted by microRNAs and RNA-binding proteins constitutes a new level of regulation with important implications in metabolic homeostasis. In this review, we describe miRNAs and RBPs that control key genes involved in the insulin signaling pathway and related regulatory networks, and their impact on human metabolic diseases at the molecular level, as well as their potential use for diagnosis and future therapeutics.

Crosstalk Between LXR and Caveolin-1 Signaling Supports Cholesterol Efflux and Anti-Inflammatory Pathways in Macrophages.

Macrophages are immune cells that play crucial roles in host defense against pathogens by triggering their exceptional phagocytic and inflammatory functions. Macrophages that reside in healthy tissues also accomplish important tasks to preserve organ homeostasis, including lipid uptake/efflux or apoptotic-cell clearance. Both homeostatic and inflammatory functions of macrophages require the precise stability of lipid-rich microdomains located at the cell membrane for the initiation of downstream signaling cascades. Caveolin-1 (Cav-1) is the main protein responsible for the biogenesis of caveolae and plays an important role in vascular inflammation and atherosclerosis. The Liver X receptors (LXRs) are key transcription factors for cholesterol efflux and inflammatory gene responses in macrophages. Although the role of Cav-1 in cellular cholesterol homeostasis and vascular inflammation has been reported, the connection between LXR transcriptional activity and Cav-1 expression and function in macrophages has not been investigated. Here, using gain and loss of function approaches, we demonstrate that LXR-dependent transcriptional pathways modulate Cav-1 expression and compartmentation within the membrane during macrophage activation. As a result, Cav-1 participates in LXR-dependent cholesterol efflux and the control of inflammatory responses. Together, our data show modulation of the LXR-Cav-1 axis could be exploited to control exacerbated inflammation and cholesterol overload in the macrophage during the pathogenesis of lipid and immune disorders, such as atherosclerosis.

Tumor-Stromal Interactions in a Co-Culture Model of Human Pancreatic Adenocarcinoma Cells and Fibroblasts and Their Connection with Tumor Spread.

One key feature of pancreatic ductal adenocarcinoma (PDAC) is a dense desmoplastic reaction that has been recognized as playing important roles in metastasis and therapeutic resistance. We aim to study tumor-stromal interactions in an in vitro coculture model between human PDAC cells (Capan-1 or PL-45) and fibroblasts (LC5). Confocal immunofluorescence, Enzyme-Linked Immunosorbent Assay (ELISA), and Western blotting were used to evaluate the expressions of activation markers; cytokines arrays were performed to identify secretome profiles associated with migratory and invasive properties of tumor cells; extracellular vesicle production was examined by ELISA and transmission electron microscopy. Coculture conditions increased FGF-7 secretion and α-SMA expression, characterized by fibroblast activation and decreased epithelial marker E-cadherin in tumor cells. Interestingly, tumor cells and fibroblasts migrate together, with tumor cells in forming a center surrounded by fibroblasts, maximizing the contact between cells. We show a different mechanism for tumor spread through a cooperative migration between tumor cells and activated fibroblasts. Furthermore, IL-6 levels change significantly in coculture conditions, and this could affect the invasive and migratory capacities of cells. Targeting the interaction between tumor cells and the tumor microenvironment might represent a novel therapeutic approach to advanced PDAC.

Blood Predictive Biomarkers for Patients With Non-small-cell Lung Cancer Associated With Clinical Response to Nivolumab.

BACKGROUND: Immunotherapy is a promising cancer treatment, but surrogate biomarkers of clinical efficacy have not been fully validated. The aim of this work was to evaluate several biomarkers as predictors of response to nivolumab monotherapy in patients with non-small-cell lung cancer. PATIENTS AND METHODS: Blood samples was collected at baseline, at 2 months after treatment start, and at disease progression. Lactate dehydrogenase level (LDH), neutrophils, and leukocyte values were obtained from medical record. Interleukin (IL)-8, IL-11, and kynurenine/tryptophan levels were determined by enzyme-linked immunosorbent assay. Total protein was extracted from circulating CD8+ T cells, and BCL-2 interacting mediator of cell death (BIM) protein expression tested by western blotting. RESULTS: Baseline LDH levels were significantly higher in non-responder patients than in those who responded (P = .045). The increase in indoleamine 2,3 dioxygenase activity was related to progression of disease, mainly in patients who did not respond to nivolumab treatment (P = .001). Increased levels of circulating IL-8 were observed in initially responding patients at time of progression, and it was related to lower overall survival (hazard ratio, 7.49; P = .025). A highest expression of BIM in circulating CD8+ T cells could be related to clinical benefit. The Student t test and Mann-Whitney U test were used to compare groups for continuous variables. Time to events was estimated using the Kaplan-Meier method, and compared by the log-rank test. CONCLUSIONS: Changes in plasma LDH and IL-8, indoleamine 2,3 dioxygenase activity, and BIM expression in CD8+ T cells could be used to monitor and predict clinical benefit from nivolumab treatment in these patients.

Blood mRNA expression of REV3L and TYMS as potential predictive biomarkers from platinum-based chemotherapy plus pemetrexed in non-small cell lung cancer patients.

PURPOSE: Therapeutic options for cancer patients have increased in the last years, although drugs resistance problem remains unresolved. Genetic background in individual susceptibility to cancer treatment could influence the therapy responses. The aim of this study was to explore the feasibility of using blood 4 genes (AEG-1, BRCA-1, REV3L and TYMS) expression levels as a predictor of the efficacy of pemetrexed therapy in patients with advanced non-small cell lung cancer. METHODS: Sixteen patients from the Medical Oncology Department at "12 de Octubre" Hospital, were included in the study. Total mRNA was isolated from blood samples, and gene expression was analyzed by RT-qPCR. A panel of lung tumor cell lines were used in cell proliferation tests and siRNA-mediated silencing assays. RESULTS: Similarity between blood gene expression levels and protein expression in matched tumor tissue was observed in 54.54% (REV3L) and 81.81% (TYMS) of cases. Gene expression of REV3L and TYMS in blood correlated directly and inversely, respectively, with progression-free survival and overall survival in the patients from our cohort. In tumor cell lines, the knockdown of REV3L conferred resistance to pemetrexed treatment, and the TYMS silencing increased the pemetrexed sensitivity of tumor cells. CONCLUSIONS: The use of peripheral blood samples for expression quantification of interest genes is an affordable method with promising results in the evaluation of response to pemetrexed treatment. Therefore, expression levels of REV3L and TYMS genes might be used as predictive biomarkers in advanced NSCLC patients.

MicroRNA 7 Impairs Insulin Signaling and Regulates Aß Levels through Posttranscriptional Regulation of the Insulin Receptor Substrate 2, Insulin Receptor, Insulin-Degrading Enzyme, and Liver X Receptor Pathway.

Brain insulin resistance is a key pathological feature contributing to obesity, diabetes, and neurodegenerative disorders, including Alzheimer's disease (AD). Besides the classic transcriptional mechanism mediated by hormones, posttranscriptional regulation has recently been shown to regulate a number of signaling pathways that could lead to metabolic diseases. Here, we show that microRNA 7 (miR-7), an abundant microRNA in the brain, targets insulin receptor (INSR), insulin receptor substrate 2 (IRS-2), and insulin-degrading enzyme (IDE), key regulators of insulin homeostatic functions in the central nervous system (CNS) and the pathology of AD. In this study, we found that insulin and liver X receptor (LXR) activators promote the expression of the intronic miR-7-1 in vitro and in vivo, along with its host heterogeneous nuclear ribonucleoprotein K (HNRNPK) gene, encoding an RNA binding protein (RBP) that is involved in insulin action at the posttranscriptional level. Our data show that miR-7 expression is altered in the brains of diet-induced obese mice. Moreover, we found that the levels of miR-7 are also elevated in brains of AD patients; this inversely correlates with the expression of its target genes IRS-2 and IDE. Furthermore, overexpression of miR-7 increased the levels of extracellular Aß in neuronal cells and impaired the clearance of extracellular Aß by microglial cells. Taken together, these results represent a novel branch of insulin action through the HNRNPK-miR-7 axis and highlight the possible implication of these posttranscriptional regulators in a range of diseases underlying metabolic dysregulation in the brain, from diabetes to Alzheimer's disease.

Influence of mineral waters on in vitro proliferation, antioxidant response and cytokine production in a human lung fibroblasts cell line.

Spa mineral waters are used for the treatment of chronic diseases' symptoms. Anti-inflammatory, analgesic, anti-ageing and tissue repair effects have been attributed to them. This work seeks to improve knowledge about the effect of spa mineral waters on human cells. For this, human lung fibroblasts were treated with mineral waters from Ledesma, Paracuellos and Archena spas, three Spanish health resorts with different water chemical composition. A significant increase of cell proliferation together with an enhanced antioxidant capacity (reactive oxygen and nitrogen species, glutathione levels and superoxide dismutase activity) in mineral water-treated fibroblasts compared to control fibroblasts was observed. Moreover, cytokine profiling revealed an increase in the release of MIF, IL-6, CL-1, CCL-5 and ICAM-1, which are described as mediators in proliferation, wound healing and cell migration processes. In conclusion, our results could be in line with the effects attributed to spa mineral waters in wound healing strategies and oxidative damage protection.