Genome-Wide Association Study and Functional Characterization Identifies Candidate Genes for Insulin-Stimulated Glucose Uptake

Distinct tissue-specific mechanisms mediate insulin action in fasting and postprandial states. Previous genetic studies have largely focused on insulin resistance in the fasting state, where hepatic insulin action dominates. Here we studied genetic variants influencing insulin levels measured 2 h after a glucose challenge in \u3e55,000 participants from three ancestry groups. We identified ten new loci (P \u3c 5 × 10-8) not previously associated with postchallenge insulin resistance, eight of which were shown to share their genetic architecture with type 2 diabetes in colocalization analyses. We investigated candidate genes at a subset of associated loci in cultured cells and identified nine candidate genes newly implicated in the expression or trafficking of GLUT4, the key glucose transporter in postprandial glucose uptake in muscle and fat. By focusing on postprandial insulin resistance, we highlighted the mechanisms of action at type 2 diabetes loci that are not adequately captured by studies of fasting glycemic traits

Patient reported outcomes for cisplatin and radiation followed by carboplatin/paclitaxel versus carboplatin/paclitaxel for locally advanced endometrial carcinoma: An NRG oncology study.

IntroductionChemotherapy plus radiation (Cis-RT + CP) did not demonstrate superiority in prolonging relapse-free survival compared to chemotherapy alone in patients with stage III or IVA endometrial carcinoma. The impact of treatment on quality of life (QOL), neurotoxicity (NTX) and psychometric properties of the gastrointestinal (GI) symptoms subscale during treatment and up to 1 year are described herein.MethodsQOL assessments were scheduled at baseline, 6 weeks (post completion of RT (Cis-RT + CP) or prior to cycle 3 (CP)), then 18 weeks (end of treatment) and 70 weeks (1 year after the end of treatment) after starting treatment. QOL instruments included the FACT-En TOI, FACT/GOG-neurotoxicity (Ntx) subscale (short), and the gastrointestinal (GI) symptoms subscale.ResultsAt the end of treatment, patients receiving Cis-RT + CP reported a statistically significant decreased QOL when compared to CP. The decline in QOL was reflected in physical well-being, functional well-being, and endometrial cancer specific concerns, but the minimally important differences (MID) were not considered clinically meaningful. Patients in both groups reported increased chemotherapy-induced Ntx symptoms with the CP group having worse scores and reaching peak symptoms at the time of chemotherapy completion. Patients on Cis-RT + CP reported statistically significantly worse GI symptoms after radiation therapy compared to patients on CP, this occurred across assessment intervals, though the MID was not meaningful. Psychometric evaluations indicated that the GI symptom scale is reliable, valid, and responsive to change.ConclusionsPROs indicate that the chemoradiotherapy group experienced worse HRQoL and GI toxicity compared to patients randomized to chemotherapy alone for locally advanced endometrial cancer though based on the MID, these were not clinically meaningful differences. The GI symptom subscale was a reliable and valid scale that has value for future trials.Trial registrationNCT00942357

Loci for insulin processing and secretion provide insight into type 2 diabetes risk

Abstract Insulin secretion is critical for glucose homeostasis, and increased levels of the precursor proinsulin relative to insulin indicate pancreatic islet beta-cell stress and insufficient insulin secretory capacity in the setting of insulin resistance. We conducted meta-analyses of genome-wide association results for fasting proinsulin from 16 European-ancestry studies in 45,861 individuals. We found 36 independent signals at 30 loci (p value <5×10⁻⁸), which validated 12 previously reported loci for proinsulin and ten additional loci previously identified for another glycemic trait. Half of the alleles associated with higher proinsulin showed higher rather than lower effects on glucose levels, corresponding to different mechanisms. Proinsulin loci included genes that affect prohormone convertases, beta-cell dysfunction, vesicle trafficking, beta-cell transcriptional regulation, and lysosomes/autophagy processes. We colocalized 11 proinsulin signals with islet expression quantitative trait locus (eQTL) data, suggesting candidate genes, including ARSG, WIPI1, SLC7A14, and SIX3. The NKX6‐3/ANK1 proinsulin signal colocalized with a T2D signal and an adipose ANK1 eQTL signal but not the islet NKX6‐3 eQTL. Signals were enriched for islet enhancers, and we showed a plausible islet regulatory mechanism for the lead signal in the MADD locus. These results show how detailed genetic studies of an intermediate phenotype can elucidate mechanisms that may predispose one to disease

Loci for insulin processing and secretion provide insight into type 2 diabetes risk

Insulin secretion is critical for glucose homeostasis, and increased levels of the precursor proinsulin relative to insulin indicate pancreatic islet beta-cell stress and insufficient insulin secretory capacity in the setting of insulin resistance. We conducted meta-analyses of genome-wide association results for fasting proinsulin from 16 European-ancestry studies in 45,861 individuals. We found 36 independent signals at 30 loci (p value < 5 × 10−8), which validated 12 previously reported loci for proinsulin and ten additional loci previously identified for another glycemic trait. Half of the alleles associated with higher proinsulin showed higher rather than lower effects on glucose levels, corresponding to different mechanisms. Proinsulin loci included genes that affect prohormone convertases, beta-cell dysfunction, vesicle trafficking, beta-cell transcriptional regulation, and lysosomes/autophagy processes. We colocalized 11 proinsulin signals with islet expression quantitative trait locus (eQTL) data, suggesting candidate genes, including ARSG, WIPI1, SLC7A14, and SIX3. The NKX6-3/ANK1 proinsulin signal colocalized with a T2D signal and an adipose ANK1 eQTL signal but not the islet NKX6-3 eQTL. Signals were enriched for islet enhancers, and we showed a plausible islet regulatory mechanism for the lead signal in the MADD locus. These results show how detailed genetic studies of an intermediate phenotype can elucidate mechanisms that may predispose one to disease