IGF-1 ameliorates streptozotocin-induced pancreatic ß cell dysfunction and apoptosis via activating IRS1/PI3K/Akt/FOXO1 pathway.

BACKGROUND AND OBJECTIVE: Type 2 diabetes mellitus (T2DM) is an endocrine disorder with pancreatic ß cell dysfunction and/or reduced insulin sensitivity. IGF-1 is critically involved in pancreatic ß cell growth, differentiation, and insulin secretion. Insulin-mediated IRS1/PI3K/Akt/FOXO1 signaling has been proved to be closely associated with pancreatic ß cell function, hepatic glucose metabolism, and the development of T2DM. This present work was designed to demonstrate the protective role of IGF-1 against pancreatic ß cell dysfunction and to probe into the underlying mechanisms. METHODS: Herein, cell viability, cell apoptosis, insulin secretion, oxidative stress, and glycolysis in STZ-treated INS-1 cells were measured, so as to determine the biological function of IGF-1 against pancreatic ß cell dysfunction in T2DM. Additionally, whether IGF-1 could activate IRS1/PI3K/Akt/FOXO1 signaling pathway to manipulate the progression of T2DM was also investigated. RESULTS: It was discovered that IGF-1 treatment enhanced the viability and suppressed the apoptosis of STZ-treated INS-1 cells. Besides, IGF-1 treatment augmented insulin secretion of INS-1 cells in response to STZ. Moreover, IGF-1 exerted protective role against oxidative damage and displayed inhibitory effect on glycolysis in STZ-treated INS-1 cells. Mechanistically, IGF-1 treatment markedly boosted the activation of IRS1/PI3K/Akt/FOXO1 pathway. Furthermore, treatment with AG1024 (an inhibitor of IGF-1R) partially abolished the actions of IGF-1 on cell viability, cell apoptosis, insulin secretion, oxidative stress, and glycolysis in STZ-treated INS-1 cells. CONCLUSION: To conclude, IGF-1 could improve the viability and inhibit the apoptosis of STZ-treated pancreatic ß cells, induce insulin secretion, alleviate oxidative damage, as well as arrest glycolysis by activating IRS1/PI3K/Akt/FOXO1 pathway.

PPARα agonist fenofibrate relieves acquired resistance to gefitinib in non-small cell lung cancer by promoting apoptosis via PPARα/AMPK/AKT/FoxO1 pathway.

Recent studies show that intracellular accumulation of cholesterol leads to acquired resistance to gefitinib in non-small cell lung cancer (NSCLC) cells. In this study we investigated how to regulate the cholesterol levels in gefitinib-resistant NSCLC cells. We showed that intracellular cholesterol levels in gefitinib-resistant cell lines (PC-9/GR, H1975, H1650, and A549) were significantly higher than that in gefitinib-sensitive cell line (PC-9). Treatment with gefitinib (5 µM) significantly increased intracellular cholesterol levels in PC-9/GR, H1975, and H1650 cells. Gefitinib treatment downregulated the expression of PPARα, LXRα, and ABCA1, leading to dysregulation of cholesterol efflux pathway. We found that a lipid-lowering drug fenofibrate (20, 40 µM) dose-dependently increased the expression of PPARα, LXRα, and ABCA1, decreased the intracellular cholesterol levels, and enhanced the antiproliferative effects of gefitinib in PC-9/GR, H1975, and H1650 cells. We revealed that fenofibrate increased the gefitinib-induced apoptosis via regulating the key proteins involved in the intrinsic apoptosis pathway. In PC-9/GR, H1975 and H1650 cells, fenofibrate dose-dependently increased the expression of AMPK, FoxO1, and decreased the expression of AKT, which were remarkably weakened by knockdown of PPARα. In PC-9/GR cell xenograft mice, combined administration of gefitinib (25 mg · kg-1 · d-1) and fenofibrate (100 mg · kg-1 · d-1) caused remarkable inhibition on tumor growth as compared to treatment with either drug alone. All the results suggest that fenofibrate relieves acquired resistance to gefitinib in NSCLC by promoting apoptosis via regulating PPARα/AMPK/AKT/FoxO1 pathway. We propose that combination of gefitinib and fenofibrate is a potential strategy for overcoming the gefitinib resistance in NSCLC.

SPTLC1 inhibits cell growth via modulating Akt/FOXO1 pathway in renal cell carcinoma cells.

Serine palmitoyltransferase long chain-1 (SPTLC1), which is the rate-limiting enzyme for sphingolipid biosynthesis, has been indicated to be essential for carcinoma cell survival and proliferation in recent, but its role in the regulation of renal cell carcinoma (RCC) remains unknown. In the present study, we found that SPTLC1 expression was significantly decreased in RCC tissues compared to non-tumor tissues, and low SPTLC1 expression was associated with poor overall survival of RCC patients. In addition, our results revealed that forced expression of SPTLC1 could significantly inhibit cell growth in vitro and in vivo via, at least in part, modulating Akt/FOXO1 signaling pathway, thus representing a novel role of SPTLC1 in the regulation of tumor growth in RCC for the first time.

Diosmin Promotes Myogenesis via Activating the Akt/FOXO1 Pathway to Facilitate the Proliferation of C2C12 Myoblasts.

Our previous study with artificial intelligence (AI)-assisted screening found that diosmin, a natural flavonoid extracted from citrus, may affect myoblast proliferation and differentiation. At present, few studies have been conducted regarding the biological function of diosmin in muscle cells. Here, using molecular biological techniques, we found that diosmin elevated the proliferation ability of C2C12 myoblasts via activating the Akt/FOXO1 pathway to promote FOXO1 nuclear export, thus repressing p27 protein expression, increasing CDK2, CDK4, and cyclin D1 and cyclin E1 protein expression and accelerating cell cycle transformation, which contributed to myogenesis. Moreover, diosmin suppressed differentiation of C2C12 myoblasts by delaying the terminal exit of the cell cycle in early differentiated myoblasts and inhibiting autophagic flux in mature myotubes. Furthermore, diosmin promoted myogenesis by activating the Akt/FOXO1 pathway to facilitate myoblast proliferation, which had a positive biological effect on the repair of muscle injury. This study revealed the effect and mechanism of diosmin on skeletal muscle cells and simultaneously provided a new candidate drug for the treatment of myopathy.

Knockdown of PROM2 Enhances Paclitaxel Sensitivity in Endometrial Cancer Cells by Regulating the AKT/FOXO1 Pathway.

BACKGROUND: Endometrial cancer is a very common and highly lethal reproductive malignant tumour in women. Paclitaxel (PTX) is a usual drug utilized in chemotherapy for endometrial cancer. It has been uncovered that PROM2 participates in the progression of various cancers through playing a promoter. However, the regulatory function of PROM2 in PTX treatment for endometrial cancer remains unclear. METHODS: The cell viability (IC50) was examined through CCK8 assay. The mRNA and protein expressions of genes were measured through RT-qPCR and western blot. The proliferation was evaluated through colony formation and EdU assays. The cell apoptosis was assessed through flow cytometry. RESULTS: In this work, through bioinformatic analysis on online websites, it is found that the up-regulated expression of PROM2 existed in endometrial cancer. In addition, the survival probability of UCEC patients with high PROM2 expression was worse. This study adopted PTX treatment for obtaining the PTX-resistant cells (HEC-1A/PTX and KLE/PTX). Furthermore, suppression of PROM2 enhanced PTX sensitivity through decreasing IC50 and proliferation in endometrial cancer. Additionally, knockdown of PROM2 facilitated cell apoptosis in HEC-1A/PTX and KLE/PTX cells. Next, we found that silencing of PROM2 retards the AKT/FOXO1 pathway. At last, rescue assays reversed the strengthened PTX sensitivity mediated by PROM2 inhibition after SC79 treatment (AKT activator). CONCLUSION: Knockdown of PROM2 enhanced PTX sensitivity in endometrial cancer through modulating the AKT/FOXO1 pathway. This study hinted that PROM2 may be a useful therapeutic target for PTX treatment in endometrial cancer.

miR-150 regulates endothelial progenitor cell differentiation via Akt and promotes thrombus resolution.

BACKGROUND: Deep venous thrombosis (DVT) constitutes a major global disease burden. Endothelial progenitor cells (EPCs) have been described in association with recanalization of venous thrombus. Furthermore, emerging evidence suggests microRNAs are involved in this progression. The goal of this study was to investigate the influence of miR-150 on the behavior of EPCs and its potential contribution in venous thrombosis resolution. METHODS: We isolated and cultured EPCs from healthy adults. Next, early EPCs or endothelial colony-forming cells (ECFCs or late EPCs) were transfected with miR-150 agomir and antagomir. Gene expression profiles, proliferation, cytokine secretion, and angiogenic capacity of early EPCs and ECFCs were examined. The effects of miR-150 on c-Myb expression and Akt/FOXO1 signaling were also evaluated. Furthermore, a rat model of venous thrombosis was constructed to determine the in vivo function of EPCs. RESULTS: Our results showed that miR-150 overexpression in early EPCs significantly promoted differentiation to ECFCs and contributed to proliferation and tube formation. However, suppression of miR-150 in late EPCs inhibited proliferation and tube formation. Moreover, we identified that this progression is regulated by inhibition of c-Myb and activation of the Akt/FOXO1 pathway. Our findings also showed that miR-150 led to the enhanced resolution ability of EPCs in a rat venous thrombosis model. CONCLUSIONS: In this study, we present a novel mechanism of miRNA-mediated regulation of EPCs and Akt activation in thrombus resolution.

High cholesterol induces apoptosis and autophagy through the ROS-activated AKT/FOXO1 pathway in tendon-derived stem cells.

BACKGROUND: Hypercholesterolemia increases the risk of tendon pain and tendon rupture. Tendon-derived stem cells (TDSCs) play a vital role in the development of tendinopathy. Our previous research found that high cholesterol inhibits tendon-related gene expression in TDSCs. Whether high cholesterol has other biological effects on TDSCs remains unknown. METHODS: TDSCs isolated from female SD rats were exposed to 10 mg/dL cholesterol for 24 h. Then, cell apoptosis was assessed using flow cytometry and fluorescence microscope. RFP-GFP-LC3 adenovirus transfection was used for measuring autophagy. Signaling transduction was measured by immunofluorescence and immunoblotting. In addition, Achilles tendons from ApoE -/- mice fed with a high-fat diet were histologically assessed using HE staining and immunohistochemistry. RESULTS: In this work, we verified that 10 mg/dL cholesterol suppressed cell proliferation and migration and induced G0/G1 phase arrest. Additionally, cholesterol induced apoptosis and autophagy simultaneously in TDSCs. Apoptosis induction was related to increased expression of cleaved caspase-3 and BAX and decreased expression of Bcl-xL. The occurrence of autophagic flux and accumulation of LC3-II demonstrated the induction of autophagy by cholesterol. Compared with the effects of cholesterol treatment alone, the autophagy inhibitor 3-methyladenine (3-MA) enhanced apoptosis, while the apoptosis inhibitor Z-VAD-FMK diminished cholesterol-induced autophagy. Moreover, cholesterol triggered reactive oxygen species (ROS) generation and activated the AKT/FOXO1 pathway, while the ROS scavenger NAC blocked cholesterol-induced activation of the AKT/FOXO1 pathway. NAC and the FOXO1 inhibitor AS1842856 rescued the apoptosis and autophagy induced by cholesterol. Finally, high cholesterol elevated the expression of cleaved caspase-3, Bax, LC3-II, and FOXO1 in vivo. CONCLUSION: The present study indicated that high cholesterol induced apoptosis and autophagy through ROS-activated AKT/FOXO1 signaling in TDSCs, providing new insights into the mechanism of hypercholesterolemia-induced tendinopathy. High cholesterol induces apoptosis and autophagy through the ROS-activated AKT/FOXO1 pathway in tendon-derived stem cells.

Vitamin D Deficiency Induces Insulin Resistance and Re-Supplementation Attenuates Hepatic Glucose Output via the PI3K-AKT-FOXO1 Mediated Pathway.

BACKGROUND: Pandemic vitamin D deficiency is associated with insulin resistance and type 2 diabetes. Vitamin D supplementation has been reported to have improved glucose homeostasis. However, its mechanism to improve insulin sensitivity remains unclear. METHODS AND RESULTS: Male C57BL/6J mice are fed with/without vitamin D control (CD) or Western (WD) diets for 15 weeks. The vitamin-D-deficient lean (CDVDD) and obese (WDVDD) mice are further subdivided into two groups. One group is re-supplemented with vitamin D for 6 weeks and hepatic insulin signaling is examined. Both CD and WD mice with vitamin D deficiency developed insulin resistance. Vitamin D supplementation in CDVDD mice significantly improved insulin sensitivity, hepatic inflammation, and antioxidative capacity. The hepatic insulin signals like pAKT, pFOXO1, and pGSK3ß are increased and the downstream Pepck, G6pase, and Pgc1α are reduced. Furthermore, the lipogenic genes Srebp1c, Acc, and Fasn are decreased, indicating that hepatic lipid accumulation is inhibited. CONCLUSION: The results demonstrate that vitamin D deficiency induces insulin resistance. Its supplementation has significant beneficial effects on pathophysiological mechanisms in type 2 diabetes but only in lean and not in the obese phenotype. The increased subacute inflammation and insulin resistance in obesity cannot be significantly alleviated by vitamin D supplementation. This needs to be taken into consideration in the design of new clinical trials.

MiR-222 promotes drug-resistance of breast cancer cells to adriamycin via modulation of PTEN/Akt/FOXO1 pathway.

BACKGROUND AND PURPOSE: Acquisition of resistance to adriamycin (ADR) is one of the most important clinical obstacles in the treatment of breast cancer, but the molecular mechanisms underlying sensitivity to ADR remain elusive. In our previous study, through miRNA microarray and experiments, we have emphasized that miR-222 could promote the ADR-resistance in breast cancer cells. The aim of this study was to explore the possible mechanism by which miR-222 affects sensitivity to ADR. METHODS: Through pathway enrichment analyses for miR-222, we found that PTEN/Akt/FOXO1 signaling pathway may be of importance. RT-qPCR analyses and western blot assays confirmed the relationship between miR-222 expression and target genes. Immunofluorescence further visually displayed the location of FOXO1. When blocking PTEN/Akt/FOXO1 signaling pathway, we demonstrated the effects of miR-222-mediated ADR resistance by MTT and apoptosis assays. RESULTS: RT-qPCR and Western blot results showed that miR-222 expression was negatively correlated with FOXO1 expression. In addition, the subcellular translocation of FOXO1 due to the altered expression of miR-222 was observed from immunofluorescence. Moreover, upregulation of miR-222 expression in MCF-7/S cells is associated with decreased PTEN expression levels and increased phospho-Akt (p-Akt) expression. Conversely in MCF-7/ADR cells, inhibition of miR-222 resulted in increased PTEN expression and decreased p-Akt expression. For further validation, results of the present study also demonstrated that PTEN/Akt/FOXO1 signaling was responsible for the ADR-resistance of breast cancer cells since LY294002, an inhibitor of Akt signaling, partially increased the sensitivity of MCF-7/S cells to ADR. More importantly, we postulated that high expression of miR-222 is closely related to poor overall survival by TCGA database validation. CONCLUSIONS: Taken together, these data elucidated that miR-222 mediated ADR-resistance of breast cancer cells partly through regulation of PTEN/Akt/FOXO1 signaling pathway and inhibition of miR-222 may improve the prognosis of breast cancer patients.

Study on the mechanism of Poria cocos polysaccharides on the regulation of gluconeogenesis in liver of type 2 diabetic mellitus model rats / 中国药房

OBJECTIVE To investigate the effect and mechanism of Poria cocos polysaccharides on the regulation of blood glucose in type 2 diabetes mellitus （T2DM）model rats by phosphatidylinositol 3-kinase（PI3K）/protein kinase B （Akt）/forked box transcription factor O 1（FoxO1）pathway. METHODS SD rats were randomly divided into blank control group （no modeling ，no administration），model group （modeling，no administration ），metformin group （modeling，200 mg/kg）and P. cocos polysaccharide low-dose，medium-dose and high-dose groups （modeling，100，200，400 mg/kg），8 in each group. Except for blank control group ， other groups were given high fat diet combined with streptozotocin to construct the model of T 2DM rats. At the same time ， administration groups were given relevant dose of medicine intragastrically ，and blank control group and model group were given constant volume of water intragastrically ，once a day ，for consecutive 42 days. During the experiment ，general condition and bodyweight of rats were observed every day ；fasting blood glucose （FBG）of rats were collected ，and oral glucose tolerance test were conducted and area under curve （AUC）was calculated the day before last administration. After last medication ，the heart ，liver， kidney organ index were calculated ；the levels of HbA 1c，TC，TG，MDA，SOD，GSH-Px and hepatic glycogen content were detected. HE staining was used to observe the pathological changes of liver and pancreatic tissue ，and the pathological grade score was calculated. Western blot assay was used to detect the protein expressions of p-PI 3K，p-Akt，p-FoxO1， PEPCK and G 6Pase in liver tissues. RESULTS Compared with blank control group ，the rats of model group suffered cc1965@163.com from polydipsia ，polyphagia and polyuria ；the body weight ， the levels of SOD and GSH-Px ，the protein expressions of p-PI 3K，p-Akt and p-FoxO 1 were significantly decreased （P＜0.05）；liver and kidney organ index ，blood glucose level at 0，0.5 and 2 hours after intragastric administration of glucose solution ，AUC， FBG，HbA1c，serum levels of MDA ，TC，TG and hepatic glycogen content ，liver and pancreatic pathological grade score ，the protein expressions of PEPCK and G 6Pase were all increased significantly （P＜0.05）. Compared with model group ，the general condition of rats in P. cocos polysaccharide groups were all improved ，and all of above indicators had been reversed to varying degrees. CONCLUSIONS P. cocos polysaccharide can downregulate protein expressions of PEPCK and G 6Pase which are key enzymes of gluconeogenesis ，inhibit hepatic gluconeogenesis ，effectively decrease blood glucose levels and regulate glucolipid metabolism in T 2DM model rats by weakening oxidative stress and upregulating PI 3K/Akt/FoxO1 pathway.