Metformin enhances LDL-cholesterol uptake by suppressing the expression of the pro-protein convertase subtilisin/kexin type 9 (PCSK9) in liver cells.

PURPOSE: Metformin (MF) intake associates with reduced levels of circulating low-density lipoprotein-cholesterol (LDL-C). This has been attributed to the activation of AMPK, which differentially regulates the expression of multiple genes involved in cholesterol synthesis and trafficking. However, the exact mechanism underlying the LDL-C lowering effect of MF remains ambiguous. METHODS: MF-treated Hep-G2 and HuH7 cells were evaluated for cell viability and the expression status of key lipid metabolism-related genes along with LDL-C uptake efficiency. RESULTS: MF treatment resulted in decreased expression and secretion of PCSK9, increased expression of LDLR and enhanced LDL-C uptake in hepatocytes. It also resulted in increased expression of activated AMPK (p-AMPK) and decreased expression of SREBP2 and HNF-1α proteins. Transcriptomic analysis of MF-treated Hep-G2 cells confirmed these findings and showed that other key lipid metabolism-related genes including those that encode apolipoproteins (APOB, APOC2, APOC3 and APOE), MTTP and LIPC are downregulated. Lastly, MF treatment associated with reduced HMG-CoA reductase expression and activity. CONCLUSIONS: These findings suggest that MF treatment reduces circulating LDL-C levels by suppressing PCSK9 expression and enhancing LDLR expression; hence the potential therapeutic utility of MF in hypercholesterolemia.

Co-targeting BET bromodomain BRD4 and RAC1 suppresses growth, stemness and tumorigenesis by disrupting the c-MYC-G9a-FTH1axis and downregulating HDAC1 in molecular subtypes of breast cancer.

BET bromodomain BRD4 and RAC1 oncogenes are considered important therapeutic targets for cancer and play key roles in tumorigenesis, survival and metastasis. However, combined inhibition of BRD4-RAC1 signaling pathways in different molecular subtypes of breast cancer including luminal-A, HER-2 positive and triple-negative breast (TNBC) largely remains unknown. Here, we demonstrated a new co-targeting strategy by combined inhibition of BRD4-RAC1 oncogenic signaling in different molecular subtypes of breast cancer in a context-dependent manner. We show that combined treatment of JQ1 (inhibitor of BRD4) and NSC23766 (inhibitor of RAC1) suppresses cell growth, clonogenic potential, cell migration and mammary stem cells expansion and induces autophagy and cellular senescence in molecular subtypes of breast cancer cells. Mechanistically, JQ1/NSC23766 combined treatment disrupts MYC/G9a axis and subsequently enhances FTH1 to exert antitumor effects. Furthermore, combined treatment targets HDAC1/Ac-H3K9 axis, thus suggesting a role of this combination in histone modification and chromatin modeling. C-MYC depletion and co-treatment with vitamin-C sensitizes different molecular subtypes of breast cancer cells to JQ1/NSC23766 combination and further reduces cell growth, cell migration and mammosphere formation. Importantly, co-targeting RAC1-BRD4 suppresses breast tumor growth in vivo using xenograft mouse model. Clinically, RAC1 and BRD4 expression positively correlates in breast cancer patient's samples and show high expression patterns across different molecular subtypes of breast cancer. Both RAC1 and BRD4 proteins predict poor survival in breast cancer patients. Taken together, our results suggest that combined inhibition of BRD4-RAC1 pathways represents a novel and potential therapeutic approach in different molecular subtypes of breast cancer and highlights the importance of co-targeting RAC1-BRD4 signaling in breast tumorigenesis via disruption of C-MYC/G9a/FTH1 axis and down regulation of HDAC1.

Copine 3 "CPNE3" is a novel regulator for insulin secretion and glucose uptake in pancreatic ß-cells.

Copine 3 (CPNE3) is a calcium-dependent phospholipid-binding protein that has been found to play an essential role in cancer progression and stages. However, its role in pancreatic ß-cell function has not been investigated. Therefore, we performed a serial of bioinformatics and functional experiments to explore the potential role of Cpne3 on insulin secretion and ß-cell function in human islets and INS-1 (832/13) cells. RNA sequencing and microarray data revealed that CPNE3 is highly expressed in human islets compared to other CPNE genes. In addition, expression of CPNE3 was inversely correlated with HbA1c and reduced in human islets from hyperglycemic donors. Silencing of Cpne3 in INS-1 cells impaired glucose-stimulated insulin secretion (GSIS), insulin content and glucose uptake efficiency without affecting cell viability or inducing apoptosis. Moreover, mRNA and protein expression of the key regulators in glucose sensing and insulin secretion (Insulin, GLUT2, NeuroD1, and INSR) were downregulated in Cpne3-silenced cells. Taken together, data from the present study provides a new understanding of the role of CPNE3 in maintaining normal ß-cell function, which might contribute to developing a novel target for future management of type 2 diabetes therapy.

Ferritin heavy chain (FTH1) exerts significant antigrowth effects in breast cancer cells by inhibiting the expression of c-MYC.

Overexpression of ferritin heavy chain (FTH1) often associates with good prognosis in breast cancer (BCa), particularly in the triple-negative subtype (triple-negative breast cancer). However, the mechanism by which FTH1 exerts its possible tumor suppressor effects in BCa is not known. Here, we examined the bearing of FTH1 silencing or overexpression on several aspects of BCa cell growth in vitro. FTH1 silencing promoted cell growth and mammosphere formation, increased c-MYC expression, and reduced cell sensitivity to chemotherapy. In contrast, FTH1 overexpression inhibited cell growth, decreased c-MYC expression, and sensitized cancer cells to chemotherapy; silencing of c-MYC recapitulated the effects of FTH1 overexpression. These findings show for the first time that FTH1 suppresses tumor growth by inhibiting the expression of key oncogenes, such as c-MYC.

Vitamin A levels are decreased but not influenced by glucose- or lipid-lowering medications in subjects with type 2 diabetes.

BACKGROUND AND AIM: Type 2 diabetes (T2D) is a complex polygenic disease with unclear mechanisms. Clinical studies on the association of vitamin A with T2D in humans are still controversial. Herein, we aimed to investigate the plasma levels of vitamin A, predictor factors, and its correlations with clinical phenotypes in Emirati population. The effect of glucose-and lipid-lowering medications on vitamin A levels was also studied. METHODS: A cross-sectional cohort comprised 158 T2D-subjects and 90 healthy controls were recruited from the United Arab Emirates National Diabetes Study (UAEDIAB). All anthropometric, clinical, and biomedical measurements were collected. Plasma levels of vitamin A were determined using ELISA assay. RESULTS: Levels of vitamin A were significantly lower in T2D-subjects compared to healthy control (p < 0.01). Vitamin A levels were unaffected by gender base and inversely correlated with age, fasting blood glucose (FBG), glycated hemoglobin (HbA1c), waist circumference, triglycerides, and body mass index (BMI). Regression analysis revealed that HbA1c and age are predictors for vitamin A. Intake of glucose- or lipid-lowering medications showed no effect on vitamin A levels. CONCLUSION: HbA1c and age are predictors for low levels of vitamin A among Emirati-T2D subjects. No influence of glucose and lipid-lowering medications on the plasma levels of vitamin A.

Combined intake of glucose-and lipid-lowering medications further elevates plasma levels of PCSK9 in type 2 diabetes patients.

BACKGROUND AND AIM: This study examined the status of plasma levels of protein convertase subtilisin/kexin 9 (PCSK9) in association with glucose-and lipid-lowering medications in subjects with type 2 diabetes (T2D). METHODS: This study comprised 177 diabetics and 115 non-diabetic subjects recruited from the United Arab Emirates National Diabetes Study (UAEDIAB). Clinical and biomedical data were collected by standard techniques. Plasma levels of PCSK9 were determined using ELISA. RESULTS: PCSK9 levels were higher in diabetics than non-diabetics (P < 0.001). Diabetics with disease duration >5 years, HbA1c > 7.0%, or male subjects, had significantly higher levels of PCSK9 than their counterparts (P < 0.05). Regression analysis revealed that HbA1c and age are predictors for PCSK9 in T2D subjects. Diabetic subjects with abnormal lipids profile on lipid-lowering medications had a higher level of PCSK9 compared to those with normal lipids profile (85.6 ± 40.5 vs. 63.7 ± 39.5 ng/ml, respectively; P < 0.01). Diabetics on combined intake of insulin and oral glucose-lowering drugs had higher levels of PCSK9 than those not taking any (86.1 ± 41.6 vs 69.7 ± 36.1 ng/ml, respectively; P < 0.05). The highest levels of PCSK9 however, were in diabetics on combined lipid- and glucose-lowering therapy when compared to those, not on any (96.2 ± 34.0 vs 66.0 ± 35.1 ng/ml, respectively; P < 0.01). CONCLUSIONS: Age and HbA1c are the most predictors for the elevated levels of PCSK9 in Emirati T2D subjects. Combined therapy of glucose-and lipid-lowering medications further elevates plasma levels of PCSK9 in diabetic subjects.

Estrogen signaling differentially alters iron metabolism in monocytes in an Interleukin 6-dependent manner.

The ability of monocytes to release or sequester iron affects their role in cancer and inflammation. Previous work has shown that while IL-6 upregulates hepcidin synthesis and enhances iron sequestration, E2 reduces hepcidin synthesis and increases iron release. Given that E2 upregulates IL-6 production in monocytes, it is likely that the exact effect of E2 on iron metabolism in monocytes is shaped by its effect on IL-6 expression. To address this issue, the expression of key iron regulatory proteins was assessed in E2-treated U937, HuT-78, THP-1 and Hep-G2 cells. Iron status was also evaluated in U937 cells treated with the ERα agonist PPT, the ER antagonist ICI-182780, dexamethasone + E2, IL-6 + E2 and in IL-6-silenced U937 cells. E2 treatment reduced hepcidin synthesis in HuT-78, THP-1 and Hep-G2 cells but increased hepcidin synthesis and reduced FPN expression in U937 cells. E2-treated U937 cells also showed reduced HIF-1α and FTH expression and increased TFR1 expression, which associated with increased labile iron content as compared with similarly treated Hep-G2 cells. While treatment of U937 cells with interleukin 6 (IL-6) resulted in increased expression of hepcidin, dexamethasone treatment resulted in reduced hepcidin synthesis relative to E2- or dexamethasone + E2-treated cells; IL-6 silencing also resulted in reduced hepcidin synthesis in U937 cells. Lastly, while iron depletion resulted in increased cell death in U937 cells, E2 treatment resulted in enhanced cell survival and reduced apoptosis. These findings suggest that E2 differentially alters iron metabolism in monocytes in an IL-6 dependent manner.

Waist circumference is a major determinant of oxidative stress in subjects with and without metabolic syndrome.

AIM: Oxidative stress (OS) plays a major role in pathogenic mechanisms associated with metabolic syndrome (Mets) yet the main component of Mets contributing most to OS is not well elucidated. Hence, the aim of this study was to investigate the oxidative-antioxidative status in Mets subjects and to determine the main predicting component of OS. METHODS: Anthropometric measures, fasting blood glucose, lipid profile, antioxidant enzymes [catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx)], reduced glutathione (GSH), malondialdehyde (MDA) and protein carbonyl were assessed in 172 adult UAE residents. International Diabetes Federation criteria were used for Mets diagnosis. Mets Scores (0-5) were calculated and assigned per subject based on number of components. RESULTS: Of all participants, 22.1% had Mets and 49.4% had large waist circumference (WC). Significant lower levels of catalase, SOD, GPx and GSH, and higher levels of MDA and protein carbonyl were observed in subjects with Mets. In addition, catalase, SOD, GPx, and GSH correlated negatively, while MDA and protein carbonyl correlated positively with almost all Mets components. Similar trend of correlations was noticed with Mets Scores. When adjusted for age and gender, linear regression analysis revealed that subjects with large WC demonstrated significantly lower levels of antioxidative enzymes and GSH, and higher levels of MDA and protein carbonyl. Consequently, WC emerged as the best predictor of OS. CONCLUSIONS: The degree of OS is dependent on the Mets Scores, and WC contributes independently to increased OS among adults in UAE.

Relationship of salivary adipocytokines, diet quality, physical activity, and nutrition status in adult Emirati females in United Arab Emirates.

AIMS: The United Arab Emirates (UAE) ranks as the fifth most obese country with increasing cardio-metabolic risks. In this paper, relationships of salivary adipocytokines (markers of cardio-metabolic syndrome), diet quality and physical activity in 90 normal-weight, overweight and obese (30 subjects in each group) Emirati adult females were investigated. METHODS: A cross-sectional research design was adopted. Anthropometric measurements, diet quality and physical activity questionnaires were administered. Overnight fasting saliva was collected to determine levels of adiponectin, interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-α). RESULTS: Salivary adiponectin was significantly lower, while TNF-α was higher in obese than normal-weight subjects. IL-10 displayed a lower trend in obese subjects. Though diet quality and physical activity did not exhibit significant differences among the three groups, better diet quality and higher physical activity level were reported among normal-weight subjects. Salivary TNF-α correlated positively with body mass index (BMI) (r = 0.37; p < 0.001) and waist circumference (r = 0.31; p < 0.001), while adiponectin correlated negatively with BMI (r = -0.28; p < 0.05). IL-10 showed negative trend in correlation with obesity measures. Correlations were not observed between diet quality and physical activity with salivary adipocytokines. Interestingly, a significant negative correlation emerged between diet quality and neck circumference (r = -0.24; p < 0.05). CONCLUSION: Our findings demonstrate that salivary adipocytokines correlate with obesity measures and can serve as convenient adjunct method in predicting cardio-metabolic risks in the population.