Regulation on Citrate Influx and Metabolism through Inhibiting SLC13A5 and ACLY: A Novel Mechanism Mediating the Therapeutic Effects of Curcumin on NAFLD.

Upregulated de novo lipogenesis (DNL) plays a pivotal role in the progress of the nonalcoholic fatty liver disease (NAFLD). Cytoplasmic citrate flux, mediated by plasma membrane citrate transporter (SLC13A5), mitochondrial citrate carrier (SLC25A1), and ATP-dependent citrate lyase (ACLY), determines the central carbon source for acetyl-CoA required in DNL. Curcumin, a widely accepted dietary polyphenol, can attenuate lipid accumulation in NAFLD. Here, we first investigated the lipid-lowering effect of curcumin against NAFLD in oleic and palmitic acid (OPA)-induced primary mouse hepatocytes and high-fat plus high-fructose diet (HFHFD)-induced mice. Curcumin profoundly attenuated OPA- or HFHFD-induced hyperlipidemia and aberrant hepatic lipid deposition via modulating the expression and function of SLC13A5 and ACLY. The possible mechanism of curcumin on the citrate pathway was investigated using HepG2 cells, HEK293T cells transfected with human SLC13A5, and recombinant human ACLY. In OPA-stimulated HepG2 cells, curcumin rectified the dysregulated expression of SLC13A5/ACLY possibly via the AMPK-mTOR signaling pathway. Besides, curcumin also functionally inhibited both citrate transport and metabolism mediated by SLC13A5 and ACLY, respectively. These findings confirm that curcumin improves the lipid accumulation in the liver by blocking citrate disposition and hence may be used to prevent NAFLD.

Racial disparities in survival outcomes among breast cancer patients by molecular subtypes.

PURPOSE: Differences in tumor biology, genomic architecture, and health care delivery patterns contribute to the breast cancer mortality gap between White and Black patients in the US. Although this gap has been well documented in previous literature, it remains uncertain how large the actual effect size of race is for different survival outcomes and the four breast cancer subtypes. METHODS: We established a breast cancer patient cohort at the University of Chicago Comprehensive Cancer Center. We chose five major survival outcomes to study: overall survival, recurrence-free survival, breast-cancer-specific survival, time-to-recurrence and post-recurrence survival. Cox proportional hazards models were used to estimate the hazard ratios between Black and White patients, adjusting for selected patient, tumor, and treatment characteristics, and also stratified by the four breast cancer subtypes. RESULTS: The study included 2795 stage I-III breast cancer patients (54% White and 38% Black). After adjusting for selected patient, tumor and treatment characteristics, Black patients still did worse than White patients in all five survival outcomes. The racial difference was highest within the HR-/HER2+ subgroup, in both overall survival (hazard ratio = 4.00, 95% CI 1.47-10.86) and recurrence-free survival (hazard ratio = 3.00, 95% CI 1.36-6.60), adjusting for age at diagnosis, cancer stage, and comorbidities. There was also a significant racial disparity within the HR+/HER2- group in both overall survival and recurrence-free survival. CONCLUSIONS: Our study confirmed that racial disparity existed between White and Black breast cancer patients in terms of both survival and recurrence, and found that this disparity was largest among HR-/HER2+ and HR+/HER2- patients.

Tanshinone IIA prevents LPS-induced inflammatory responses in mice via inactivation of succinate dehydrogenase in macrophages.

Metabolic reprogramming is associated with NLRP3 inflammasome activation in activated macrophages, contributing to inflammatory responses. Tanshinone IIA (Tan-IIA) is a major constituent from Salvia miltiorrhiza Bunge, which exhibits anti-inflammatory activity. In this study, we investigated the effects of Tan-IIA on inflammation in macrophages in focus on its regulation of metabolism and redox state. In lipopolysaccharides (LPS)-stimulated mouse bone marrow-derived macrophages (BMDMs), Tan-IIA (10 µM) significantly decreased succinate-boosted IL-1ß and IL-6 production, accompanied by upregulation of IL-1RA and IL-10 release via inhibiting succinate dehydrogenase (SDH). Tan-IIA concentration dependently inhibited SDH activity with an estimated IC50 of 4.47 µM in LPS-activated BMDMs. Tan-IIA decreased succinate accumulation, suppressed mitochondrial reactive oxygen species production, thus preventing hypoxia-inducible factor-1α (HIF-1α) induction. Consequently, Tan-IIA reduced glycolysis and protected the activity of Sirtuin2 (Sirt2), an NAD+-dependent protein deacetylase, by raising the ratio of NAD+/NADH in activated macrophages. The acetylation of α-tubulin was required for the assembly of NLRP3 inflammasome; Tan-IIA increased the binding of Sirt2 to α-tubulin, and thus reduced the acetylation of α-tubulin, thus impairing this process. Sirt2 knockdown or application of Sirt2 inhibitor AGK-2 (10 µM) neutralized the effects of Tan-IIA, suggesting that Tan-IIA inactivated NLRP3 inflammasome in a manner dependent on Sirt2 regulation. The anti-inflammatory effects of Tan-IIA were observed in mice subjected to LPS challenge: pre-administration of Tan-IIA (20 mg/kg, ip) significantly attenuated LPS-induced acute inflammatory responses, characterized by elevated IL-1ß but reduced IL-10 levels in serum. The peritoneal macrophages isolated from the mice displayed similar metabolic regulation. In conclusion, Tan-IIA reduces HIF-1α induction via SDH inactivation, and preserves Sirt2 activity via downregulation of glycolysis, contributing to suppression of NLRP3 inflammasome activation. This study provides a new insight into the anti-inflammatory action of Tan-IIA from the respect of metabolic and redox regulation.