Design and synthesis of Atglistatin derivatives as adipose triglyceride lipase inhibitors

Synthesis of Hydantoin Androgen Receptor Antagonists and Study on Their Antagonistic Activity

Hydroxymethylthiohydantoin, hydroxymethylthiohydantoin, and hydantoin, containing a pyridine group, were synthesized to study their androgen receptor antagonistic activities. Among them, compounds 6a/6c/7g/19a/19b exhibited excellent androgen receptor antagonistic activity, which was consistent with or even superior to enzalutamide. In addition, compounds 19a and 19b exhibited better antiproliferative activity than enzalutamide in prostate cancer cells. The results show that compound 19a has great potential as a new AR antagonist.

Piceatannol, a Dietary Polyphenol, Alleviates Adipose Tissue Loss in Pre-Clinical Model of Cancer-Associated Cachexia via Lipolysis Inhibition

Cancer-associated cachexia (CAC) is the nutrition-independent loss of lean muscle and adipose tissues, and results in reduced chemotherapy effectiveness and increased mortality. Preventing adipose loss is considered a key target in the early stages of cachexia. Lipolysis is considered the central driver of adipose loss in CAC. We recently found that piceatannol, but not its analogue resveratrol, exhibits an inhibitory effect on lipolysis. The objective of this study was to investigate the role of piceatannol in cancer-associated lipolysis and cachexia-induced weight loss. Cancer cell-induced lipolysis in adipocytes was stimulated using cancer-conditioned media (CCM) or co-culture with human pancreatic cancer cells and the cachexia-associated cytokines TNF-α and interleukin-6 in 3T3-L1 adipocytes. C26 colon carcinoma-bearing mice were modeled using CAC in vivo. Piceatannol reduced cancer-associated lipolysis by at least 50% in both CCM and cytokine-induced lipolysis in vitro. Further gene and protein analysis confirmed that piceatannol modulated the stability of lipolytic proteins. Moreover, piceatannol protected tumor-bearing mice against weight-loss in early stages of CAC largely through preserving adipose tissue, with no effect on survival. This study demonstrates the use of a dietary compound to preserve adipose in models of early stage CAC and provides groundwork for further investigation of piceatannol or piceatannol-rich foods as alternative medicine in the preservation of body fat mass and future CAC therapy.

Metabolic Remodeling Induced by Adipocytes: A New Achilles' Heel in Invasive Breast Cancer?

Metabolic reprogramming represents an important hallmark of cancer cells. Besides de novo fatty acid synthesis, it is now clear that cancer cells can acquire Fatty Acids (FA) from tumor-surrounding adipocytes to increase their invasive capacities. Indeed, adipocytes release FA in response to tumor secreted factors that are transferred to tumor cells to be either stored as triglycerides and other complex lipids or oxidized in mitochondria. Like all cells, FA can be released over time from triglyceride stores through lipolysis and then oxidized in mitochondria in cancer cells. This metabolic interaction results in specific metabolic remodeling in cancer cells, and underpins adipocyte stimulated tumor progression. Lipolysis and fatty acid oxidation therefore represent novel targets of interest in the treatment of cancer. In this review, we summarize the recent advances in our understanding of the metabolic reprogramming induced by adipocytes, with a focus on breast cancer. Then, we recapitulate recent reports studying the effect of lipolysis and fatty acid oxidation inhibitors on tumor cells and discuss the interest to target these metabolic pathways as new therapeutic approaches for cancer.

Structure-activity relationship studies for the development of inhibitors of murine adipose triglyceride lipase (ATGL)

High serum fatty acid (FA) levels are causally linked to the development of insulin resistance, which eventually progresses to type 2 diabetes and non-alcoholic fatty liver disease (NAFLD) generalized in the term metabolic syndrome. Adipose triglyceride lipase (ATGL) is the initial enzyme in the hydrolysis of intracellular triacylglycerol (TG) stores, liberating fatty acids that are released from adipocytes into the circulation. Hence, ATGL-specific inhibitors have the potential to lower circulating FA concentrations, and counteract the development of insulin resistance and NAFLD. In this article, we report about structure-activity relationship (SAR) studies of small molecule inhibitors of murine ATGL which led to the development of Atglistatin. Atglistatin is a specific inhibitor of murine ATGL, which has proven useful for the validation of ATGL as a potential drug target.

The Role of Adipose Triglyceride Lipase and Cytosolic Lipolysis in Cardiac Function and Heart Failure

Heart failure is one of the leading causes of death worldwide. New therapeutic concepts are urgently required to lower the burden of heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF), the two major forms of heart failure. Lipolytic processes are induced during the development of heart failure and occur in adipose tissue and multiple organs, including the heart. Increasing evidence suggests that cellular lipolysis, in particular, adipose triglyceride lipase (ATGL) activity, has an important function in cardiac (patho)physiology. This review summarizes the crucial role of cellular lipolysis for normal cardiac function and for the development of HFrEF and HFpEF. We discuss the most relevant pre-clinical studies and elaborate on the cardiac consequences of non-myocardial and myocardial lipolysis modulation. Finally, we critically analyze the therapeutic importance of pharmacological ATGL inhibition as a potential treatment option for HFrEF and/or HFpEF in the future.

An ethanolic extract of Artemisia scoparia inhibits lipolysis in vivo and has antilipolytic effects on murine adipocytes in vitro

An ethanolic extract of Artemisia scoparia (SCO) has metabolically favorable effects on adipocyte development and function in vitro and in vivo. In diet-induced obese mice, SCO supplementation significantly reduced fasting glucose and insulin levels. Given the importance of adipocyte lipolysis in metabolic health, we hypothesized that SCO modulates lipolysis in vitro and in vivo. Free fatty acids and glycerol were measured in the sera of mice fed a high-fat diet with or without SCO supplementation. In cultured 3T3-L1 adipocytes, the effects of SCO on lipolysis were assessed by measuring glycerol and free fatty acid release. Microarray analysis, qPCR, and immunoblotting were used to assess gene expression and protein abundance. We found that SCO supplementation of a high-fat diet in mice substantially reduces circulating glycerol and free fatty acid levels, and we observed a cell-autonomous effect of SCO to significantly attenuate tumor necrosis factor-α (TNFα)-induced lipolysis in cultured adipocytes. Although several prolipolytic and antilipolytic genes were identified by microarray analysis of subcutaneous and visceral adipose tissue from SCO-fed mice, regulation of these genes did not consistently correlate with SCO's ability to reduce lipolytic metabolites in sera or cell culture media. However, in the presence of TNFα in cultured adipocytes, SCO induced antilipolytic changes in phosphorylation of hormone-sensitive lipase and perilipin. Together, these data suggest that the antilipolytic effects of SCO on adipose tissue play a role in the ability of this botanical extract to improve whole body metabolic parameters and support its use as a dietary supplement to promote metabolic resiliency.

Pharmacological intervention of liver triacylglycerol lipolysis: The good, the bad and the ugly

Excessive triacylglycerol (TG) accumulation is the distinctive feature of obesity. In the liver, sustained TG accretion leads to nonalcoholic fatty liver disease (NAFLD), eventually progressing to non-alcoholic steatohepatitis (NASH) and cirrhosis, which is associated with complications including hepatic failure, hepatocellular carcinoma and death. Pharmacological interventions are actively pursued to prevent lipid accumulation in hepatocytes and, therefore, to ameliorate the associated pathophysiological conditions. Here, we sought to provide an overview of the pharmacological approaches to up- or downregulate the expression and activities of the enzymes involved in hepatic TG hydrolysis. Fatty acids (FA) released by hydrolysis of hepatic TG can be used for β-oxidation, signaling, and for very low-density lipoprotein (VLDL)-TG synthesis. Originally, lipolysis was believed to be centered in the adipose and to be catalyzed by only two lipases, hormone-sensitive lipase (HSL) and monoacylglycerol lipase (MAGL). However, genetic ablation of HSL expression in mice failed to erase TG hydrolysis in adipocytes leading to the identification of a third lipase termed adipose triglyceride lipase (ATGL). Although these three enzymes are considered to be the main players governing lipolysis in the adipocyte, other lipolytic enzymes have been described to contribute to hepatic TG metabolism. These include adiponutrin/patatin-like phospholipase domain containing 3 (PNPLA3), some members of the carboxylesterase family (CES/Ces), arylacetamide deacetylase (AADAC), lysosomal acid lipase (LAL) and hepatic lipase (HL). This review highlights the consequences of pharmacological interventions of liver lipases that degrade TG in cytosolic lipid droplets, in the endoplasmic reticulum, in the late endosomes/lysosomes and along the secretory route.