Aberrant lipid metabolism is an established hallmark of cancer cells. In particular, ether lipid levels have been shown to be elevated in tumors, but their specific function in cancer remains elusive. We show here that the metabolic enzyme alkylglyceronephosphate synthase (AGPS), a critical step in the synthesis of ether lipids, is up-regulated across multiple types of aggressive human cancer cells and primary tumors. We demonstrate that ablation of AGPS in cancer cells results in reduced cell survival, cancer aggressiveness, and tumor growth through altering the balance of ether lipid, fatty acid, eicosanoid, and fatty acidderived glycerophospholipid metabolism, resulting in an overall reduction in the levels of several oncogenic signaling lipids. Taken together, our results reveal that AGPS, in addition to maintaining ether lipids, also controls cellular utilization of fatty acids, favoring the generation of signaling lipids necessary for promoting the aggressive features of cancer.cancer metabolism | metabolomics | lipid signaling lysophosphatidic acid | eicosanoids

Marijuana and aspirin have been used for millennia to treat a wide range of maladies including pain and inflammation. Both cannabinoids, like marijuana, that exert anti-inflammatory action through stimulating cannabinoid receptors, and cyclooxygenase (COX) inhibitors, like aspirin, that suppress pro-inflammatory eicosanoid production have shown benefitial outcomes in mouse models of neurodegenerative diseases and cancer. Both cannabinoids and COX inhibitors, however, have untoward effects that discourage their chronic usage, including cognitive deficits and gastrointestinal toxicity, respectively. Recent studies have uncovered that the serine hydrolase monoacylglycerol lipase (MAGL) links the endocannabinoid and eicosanoid systems together through hydrolysis of the endocannabinoid 2-arachidonoylglycerol (2-AG) to provide the major arachidonic acid (AA) precursor pools for pro-inflammatory eicosanoid synthesis in specific tissues. Studies in recent years have shown that MAGL inhibitors elicit anti-nociceptive, anxiolytic, and anti-emetic responses and attenuate precipitated withdrawal symptoms in addiction paradigms through enhancing endocannabinoid signaling. MAGL inhibitors have also been shown to exert anti-inflammatory action in the brain and protect against neurodegeneration through lowering eicosanoid production. In cancer, MAGL inhibitors have been shown to have anti-cancer properties not only through modulating the endocannabinoid—eicosanoid network, but also by controlling fatty acid release for the synthesis of protumorigenic signaling lipids. Thus, MAGL serves as a critical node in simultaneously coordinating multiple lipid signaling pathways in both physiological and disease contexts. This review will discuss the diverse (patho)physiological roles of MAGL and the therapeutic potential of MAGL inhibitors in treating a vast array of complex human diseases.

Inflammatory responses mediated by NOD2 rely on RIP2 kinase and ubiquitin ligase XIAP for the activation of nuclear factor κB (NF-κB), mitogen-activated protein kinases (MAPKs), and cytokine production. Herein, we demonstrate that selective XIAP antagonism blocks NOD2-mediated inflammatory signaling and cytokine production by interfering with XIAP-RIP2 binding, which removes XIAP from its ubiquitination substrate RIP2. We also establish that the kinase activity of RIP2 is dispensable for NOD2 signaling. Rather, the conformation of the RIP2 kinase domain functions to regulate binding to the XIAP-BIR2 domain. Effective RIP2 kinase inhibitors block NOD2 signaling by disrupting RIP2-XIAP interaction. Finally, we identify NOD2 signaling and XIAP-dependent ubiquitination sites on RIP2 and show that mutating these lysine residues adversely affects NOD2 pathway signaling. Overall, these results reveal a critical role for the XIAP-RIP2 interaction in NOD2 inflammatory signaling and provide a molecular basis for the design of innovative therapeutic strategies based on XIAP antagonists and RIP2 kinase inhibitors.

The ability to selectively degrade proteins with bifunctional small molecules has the potential to fundamentally alter therapy in a variety of diseases. However, the relatively large size of these chimeric molecules often results in challenging physico‐chemical properties (e. g., low aqueous solubility) and poor pharmacokinetics which may complicate their in vivo applications. We recently discovered an exquisitely potent chimeric BET degrader (GNE‐987) which exhibited picomolar cell potencies but also demonstrated low in vivo exposures. In an effort to improve the pharmacokinetic properties of this molecule, we discovered the first degrader‐antibody conjugate by attaching GNE‐987 to an anti‐CLL1 antibody via a novel linker. A single IV dose of the conjugate afforded sustained in vivo exposures that resulted in antigen‐specific tumor regressions. Enhancement of a chimeric protein degrader with poor in vivo properties through antibody conjugation thereby expands the utility of directed protein degradation as both a biological tool and a therapeutic possibility.

The biological and medicinal impacts of proteolysis-targeting chimeras (PROTACs) and related chimeric molecules that effect intracellular degradation of target proteins via ubiquitin ligase-mediated ubiquitination continue to grow. However, these chimeric entities are relatively large compounds that often possess molecular characteristics, which may compromise oral bioavailability, solubility, and/or in vivo pharmacokinetic properties. We therefore explored the conjugation of such molecules to monoclonal antibodies using technologies originally developed for cytotoxic payloads so as to provide alternate delivery options for these novel agents. In this report, we describe the first phase of our systematic development of antibody–drug conjugates (ADCs) derived from bromodomain-containing protein 4 (BRD4)-targeting chimeric degrader entities. We demonstrate the antigen-dependent delivery of the degrader payloads to PC3-S1 prostate cancer cells along with related impacts on MYC transcription and intracellular BRD4 levels. These experiments culminate with the identification of one degrader conjugate, which exhibits antigen-dependent antiproliferation effects in LNCaP prostate cancer cells.

De novo lipogenesis is considered the primary source of fatty acids for lipid synthesis in cancer cells, even in the presence of exogenous fatty acids. Here, we have used an isotopic fatty acid labeling strategy coupled with metabolomic profiling platforms to comprehensively map palmitic acid incorporation into complex lipids in cancer cells. We show that cancer cells and tumors robustly incorporate and remodel exogenous palmitate into structural and oncogenic glycerophospholipids, sphingolipids, and ether lipids. We also find that fatty acid incorporation into oxidative pathways is reduced in aggressive human cancer cells, and instead shunted into pathways for generating structural and signaling lipids. Our results demonstrate that cancer cells do not solely rely on de novo lipogenesis, but also utilize exogenous fatty acids for generating lipids required for proliferation and protumorigenic lipid signaling.

Background & Aims The endocannabinoid and eicosanoid lipid signaling pathways have important roles in inflammatory syndromes. Monoacylglycerol lipase (MAGL) links these pathways, hydrolyzing the endocannabinoid 2-arachidonoylglycerol to generate the arachidonic acid precursor pool for prostaglandin production. We investigated whether blocking MAGL protects against inflammation and damage from hepatic ischemia/reperfusion (I/R) and other insults. Methods We analyzed the effects of hepatic I/R in mice given the selective MAGL inhibitor JZL184, in Mgll−/− mice, FAAH−/− mice, and in Cnr1−/− and Cnr2−/− mice, which have disruptions in the cannabinoid receptors 1 and 2 (CB1/2). Liver tissues were collected and analyzed, along with cultured hepatocytes and Kupffer cells. We measured endocannabinoids, eicosanoids, and markers of inflammation, oxidative stress, and cell death using molecular biology, biochemistry, and mass spectrometry analyses. Results Wild-type mice given JZL184 and Mgll−/− mice were protected from hepatic I/R injury by a mechanism that involved increased endocannabinoid signaling via CB2 and reduced production of eicosanoids in the liver. JZL184 suppressed the inflammation and oxidative stress that mediate hepatic I/R injury. Hepatocytes were the major source of hepatic MAGL activity and endocannabinoid and eicosanoid production. JZL184 also protected from induction of liver injury by D-(+)-galactosamine and lipopolysaccharides or CCl4. Conclusions MAGL promotes hepatic injury via endocannabinoid and eicosanoid signaling; blockade of this pathway protects mice from liver injury. MAGL inhibitors might be developed to treat for conditions that expose the liver to oxidative stress and inflammatory damage.

Heterobifunctional compounds that direct the ubiquitination of intracellular proteins in a targeted manner via coopted ubiquitin ligases have enormous potential to transform the field of medicinal chemistry. These chimeric molecules, often termed proteolysis-targeting chimeras (PROTACs) in the chemical literature, enable the controlled degradation of specific proteins via their direction to the cellular proteasome. In this report, we describe the second phase of our research focused on exploring antibody−drug conjugates (ADCs), which incorporate BRD4-targeting chimeric degrader entities. We employ a new BRD4-binding fragment in the construction of the chimeric ADC payloads that is significantly more potent than the corresponding entity utilized in our initial studies. The resulting BRD4-degrader antibody conjugates exhibit potent and antigen-dependent BRD4 degradation and antiproliferation activities in cell-based experiments. Multiple ADCs bearing chimeric BRD4-degrader payloads also exhibit strong, antigen-dependent antitumor efficacy in mouse xenograft assessments that employ several different tumor models.