[Cross-talk between insulin signaling and cell proliferation pathways]

Plasma Metabolome Profiling by High-Performance Chemical Isotope-Labelling LC-MS after Acute and Medium-Term Intervention with Golden Berry Fruit (Physalis peruviana L.), Confirming Its Impact on Insulin-Associated Signaling Pathways

Purpose: Golden berry (Physalis peruviana L.) is an exotic fruit exported from Colombia to different countries around the world. A review of the literature tends to demonstrate a hypoglycaemic effect with an improvement in insulin sensitivity after oral ingestion of fruit extracts in animal models. However, little is known about their potential effects in humans, and very little is known about the mechanisms involved. This study aimed at identifying discriminant metabolites after acute and chronic intake of golden berry. Method: An untargeted metabolomics strategy using high-performance chemical isotope-labelling LC-MS was applied. The blood samples of eighteen healthy adults were analysed at baseline, at 6 h after the intake of 250 g of golden berry (acute intervention), and after 19 days of daily consumption of 150 g (medium-term intervention). Results: Forty-nine and 36 discriminant metabolites were identified with high confidence, respectively, after the acute and medium-term interventions. Taking into account up- and downregulated metabolites, three biological networks mainly involving insulin, epidermal growth factor receptor (EGFR), and the phosphatidylinositol 3-kinase pathway (PI3K/Akt/mTOR) were identified. Conclusions: The biological intracellular networks identified are highly interconnected with the insulin signalling pathway, showing that berry intake may be associated with insulin signalling, which could reduce some risk factors related to metabolic syndrome. Primary registry of WHO.

Rethinking the Relationship between Insulin and Cancer

In addition to being a major metabolic hormone, insulin is also a growth factor with a mitogenic effect on all cells, more marked in malignant cells that often overexpress the insulin receptor. In patients with metabolic diseases characterized by hyperinsulinemia (obesity, type 2 diabetes, and metabolic syndrome), the incidence of several types of cancer is increased, as is cancer-related mortality. Because of the worldwide growing prevalence of metabolic diseases and the diffuse use of insulin and its analogs for treating diabetes, the relationship between insulin and cancer has become a clinically relevant issue. Clinical studies have not clarified the degree to which hyperinsulinemia can influence cancer occurrence and prognosis. To better understand this issue, an improved scientific approach is required, with more careful consideration of the mechanisms related to hyperinsulinemia and carcinogenesis.

Uterine responses to early pre-attachment embryos in the domestic dog and comparisons with other domestic animal species

In the dog, there is no luteolysis in the absence of pregnancy. Thus, this species lacks any anti-luteolytic endocrine signal as found in other species that modulate uterine function during the critical period of pregnancy establishment. Nevertheless, in the dog an embryo-maternal communication must occur in order to prevent rejection of embryos. Based on this hypothesis, we performed microarray analysis of canine uterine samples collected during pre-attachment phase (days 10-12) and in corresponding non-pregnant controls, in order to elucidate the embryo attachment signal. An additional goal was to identify differences in uterine responses to pre-attachment embryos between dogs and other mammalian species exhibiting different reproductive patterns with regard to luteolysis, implantation, and preparation for placentation. Therefore, the canine microarray data were compared with gene sets from pigs, cattle, horses, and humans. We found 412 genes differentially regulated between the two experimental groups. The functional terms most strongly enriched in response to pre-attachment embryos related to extracellular matrix function and remodeling, and to immune and inflammatory responses. Several candidate genes were validated by semi-quantitative PCR. When compared with other species, best matches were found with human and equine counterparts. Especially for the pig, the majority of overlapping genes showed opposite expression patterns. Interestingly, 1926 genes did not pair with any of the other gene sets. Using a microarray approach, we report the uterine changes in the dog driven by the presence of embryos and compare these results with datasets from other mammalian species, finding common-, contrary-, and exclusively canine-regulated genes.

MicroRNA-664 Targets Insulin Receptor Substrate 1 to Suppress Cell Proliferation and Invasion in Breast Cancer

A large number of microRNAs (miRNAs) have been previously demonstrated to be dysregulated in breast cancer (BC), and alterations in miRNA expression may affect the initiation and progression of BC. This study showed that miR-664 expression was obviously reduced in BC tissues and cell lines. Resumption of the expression of miR-664 attenuated the proliferation and invasion of BC cells. The molecular mechanisms underlying the inhibitory effects of BC cell proliferation and invasion by miR-664 were also studied. Insulin receptor substrate 1 (IRS1) was identified as a novel and direct target of miR-664. In addition, siRNA-mediated silencing of IRS1 expression mimicked the suppressive effects of miR-664 overexpression in BC cells. Rescue experiments demonstrated that recovered IRS1 expression partially antagonized the inhibition of proliferation and invasion of BC cells caused by miR-664 overexpression. Thus, miR-664 may serve as a tumor suppressor in BC by directly targeting IRS1. Moreover, miR-664 downregulation in BC may contribute to the occurrence and development of BC, suggesting that miR-664 may be a novel therapeutic target for patients with BC.

Downregulation of miR-139-5p contributes to the antiapoptotic effect of liraglutide on the diabetic rat pancreas and INS-1 cells by targeting IRS1

Liraglutide is administered as glucagon-like peptide-1 (GLP-1) receptor agonist for diabetic patients and can protect pancreatic β-cells by inhibiting their apoptosis. MicroRNA-139-5p (miRNA-139-5p) participates in the regulation of cancer cell apoptosis. However, it is not clear whether miR-139-5p contributes to the anti-apoptotic effect of liraglutide in β-cells. The objective of the present study was to investigate the role of miR-139-5p on apoptosis of pancreatic β-cells. MicroRNA levels in pancreatic tissue from diabetic rats and INS-1 cells treated with liraglutide were measured by real-time quantitative RT-PCR. The role of miR-139-5p on apoptosis was studied by transfecting INS-1 cells with miR-139-5p mimics. The mRNA and protein expression of the target gene, insulin receptor substrate-1 (IRS1), were measured by qRT-PCR and Western blot, respectively. Apoptosis in rat pancreatic tissue and INS-1 cells was detected by TUNEL and annexin V/propidium iodide costaining. Apoptosis of pancreatic tissue from diabetic rats and INS-1 cells was decreased by administration of liraglutide. The expression of miR-139-5p increased in the pancreas of diabetic rats and decreased with liraglutide treatment. Incubation with liraglutide (100 nM) for 48 h attenuated the expression of miR-139-5p and increased the mRNA and protein levels of IRS1. Direct regulatory effects of miR-139-5p on IRS1 were found by a dual-luciferase reporter assay. Transfection of INS-1 cells with miR-139-5p mimics led to decreases in the mRNA and protein expression of IRS1. In conclusion, our observations suggest that decreased miR-139-5p expression contributes to the anti-apoptotic effect of liraglutide on the diabetic rat pancreas and INS-1 cells by targeting IRS1.

Maternal vitamin D-restricted diet has consequences in the formation of pancreatic islet/insulin-signaling in the adult offspring of mice

The maternal deficiency of vitamin D can act on organogenesis in mice offspring, being a risk factor for chronic diseases in adulthood. This study investigates the effects of maternal deficiency of vitamin D on structural islet remodeling and insulin-signaling pathway in the offspring. We studied male C57Bl/6 offspring at 3-month old (n = 10/group) from mother fed one of the two diets: control diet (C) or vitamin D-restricted diet (VitD^-). After weaning, offspring only fed the control diet ad libitum. In the offspring, we studied insulin production, islet remodeling, and islet protein expression of the insulin-signaling pathway (Western blotting, isolated islet, n = 5/group). VitD^- offspring showed greater glycemia (P = 0.012), smaller beta-cell mass (P = 0.014), and hypoinsulinemia (P = 0.024) than C offspring. Comparing VitD^- offspring with C offspring, we observed lower protein levels in islet of insulin (P = 0.003), insulin receptor substrate-1 (P = 0.025), phosphatidylinositol-3-kinases (P = 0.045), 3-phosphoinositide-dependent protein kinase 1 (P = 0.017), protein kinase B (P = 0.028), with reduced expression of pancreas/duodenum homeobox-1 (PDX-1) (P = 0.016), glucose transporter-2 (P = 0.003), and glucokinase (P = 0.045). The maternal vitamin D-restricted diet modifies the development of the pancreas of the offspring, leading to islet remodeling and altered insulin-signaling pathway. The decrease of PDX-1 is probably significant to the changes in the beta-cell mass and insulin secretion in adulthood.