Chemical Cryptology of Cancer’s Histone Code

Somatic mutations in non-Hodgkin's lymphoma frequently activate EZH2, a protein methyltransferase responsible for H3K27 trimethylation. In this issue of Chemistry and Biology, Bradley and coworkers describe a new set of EZH2 inhibitors amenable to probing the targetable role of H3K27 trimethylation in lymphoma

Impairment of angiogenesis by fatty acid synthase inhibition Involves mTOR malonylation

The role of fatty acid synthesis in endothelial cells (ECs) remains incompletely characterized. We report that fatty acid synthase knockdown (FASNKD) in ECs impedes vessel sprouting by reducing proliferation. Endothelial loss of FASN impaired angiogenesis in vivo, while FASN blockade reduced pathological ocular neovascularization, at >10-fold lower doses than used for anti-cancer treatment. Impaired angiogenesis was not due to energy stress, redox imbalance, or palmitate depletion. Rather, FASNKD elevated malonyl-CoA levels, causing malonylation (a post-translational modification) of mTOR at lysine 1218 (K1218). mTOR K-1218 malonylation impaired mTOR complex 1 (mTORC1) kinase activity, thereby reducing phosphorylation of downstream targets (p70S6K/4EBP1). Silencing acetyl-CoA carboxylase 1 (an enzyme producing malonyl-CoA) normalized malonyl-CoA levels and reactivated mTOR in FASNKD ECs. Mutagenesis unveiled the importance of mTOR K1218 malonylation for angiogenesis. This study unveils a novel role of FASN in metabolite signaling that contributes to explaining the anti-angiogenic effect of FASN blockade

Modular Synthesis of Cell-Permeating 2‑Ketoglutarate Esters

Cell-permeating esters of 2-ketoglutarate (2-KG) have been synthesized through a convergent sequence from two modules in two and three steps, respectively. This route provides access to a full series of mono- and disubstituted 2-KG esters, enabling us to define the effect of regioisomeric masking on metabolite release and antihypoxic activity in cell-based assays. In addition to providing insight into the biological activity of cell permeable 2-KG esters, the straightforward and modular nature of this synthetic route may prove useful for the development of next-generation 2-KG analogues for diagnostic and therapeutic applications

A chemically stable fluorescent marker of the ureter.

Surgical methods guided by exogenous fluorescent markers have the potential to define tissue types in real time. Small molecule dyes with efficient and selective renal clearance could enable visualization of the ureter during surgical procedures involving the abdomen and pelvis. These studies report the design and synthesis of a water soluble, net neutral C4\u27-O-alkyl heptamethine cyanine, Ureter-Label (UL)-766, with excellent properties for ureter visualization. This compound is accessed through a concise synthetic sequence involving an N- to O-transposition reaction that provides other inaccessible C4\u27-O-alkyl heptamethine cyanines. Unlike molecules containing a C4\u27-O-aryl substituent, which have also been used for ureter visualization, UL-766 is not reactive towards glutathione and the cellular proteome. In addition, rat models of abdominal surgery reveal that UL-766 undergoes efficient and nearly exclusive renal clearance in vivo. In total, this molecule represents a promising candidate for visualizing the ureter during a variety of surgical interventions

Global Profiling of Acetyltransferase Feedback Regulation

Lysine acetyltransferases (KATs) are key mediators of cell signaling. Methods capable of providing new insights into their regulation thus constitute an important goal. Here we report an optimized platform for profiling KAT–ligand interactions in complex proteomes using inhibitor-functionalized capture resins. This approach greatly expands the scope of KATs, KAT complexes, and CoA-dependent enzymes accessible to chemoproteomic methods. This enhanced profiling platform is then applied in the most comprehensive analysis to date of KAT inhibition by the feedback metabolite CoA. Our studies reveal that members of the KAT superfamily possess a spectrum of sensitivity to CoA and highlight NAT10 as a novel KAT that may be susceptible to metabolic feedback inhibition. This platform provides a powerful tool to define the potency and selectivity of reversible stimuli, such as small molecules and metabolites, that regulate KAT-dependent signaling

Co-opting a Bioorthogonal Reaction for Oncometabolite Detection

Dysregulated metabolism is a hallmark of many diseases, including cancer. Methods to fluorescently detect metabolites have the potential to enable new approaches to cancer detection and imaging. However, fluorescent sensing methods for naturally occurring cellular metabolites are relatively unexplored. Here we report the development of a chemical approach to detect the oncometabolite fumarate. Our strategy exploits a known bioorthogonal reaction, the 1,3-dipolar cycloaddition of nitrileimines and electron-poor olefins, to detect fumarate via fluorescent pyrazoline cycloadduct formation. We demonstrate hydrazonyl chlorides serve as readily accessible nitrileimine precursors, whose reactivity and spectral properties can be tuned to enable detection of fumarate and other dipolarophile metabolites. Finally, we show this reaction can be used to detect enzyme activity changes caused by mutations in fumarate hydratase, which underlie the familial cancer predisposition syndrome hereditary leiomyomatosis and renal cell cancer. Our studies define a novel intersection of bioorthogonal chemistry and metabolite reactivity that may be harnessed to enable biological profiling, imaging, and diagnostic applications

Impairment of Angiogenesis by Fatty Acid Synthase Inhibition Involves mTOR Malonylation

The role of fatty acid synthesis in endothelial cells (ECs) remains incompletely characterized. We report that fatty acid synthase knockdown (FASNKD) in ECs impedes vessel sprouting by reducing proliferation. Endothelial loss of FASN impaired angiogenesis in vivo, while FASN blockade reduced pathological ocular neovascularization, at >10-fold lower doses than used for anti-cancer treatment. Impaired angiogenesis was not due to energy stress, redox imbalance, or palmitate depletion. Rather, FASNKD elevated malonyl-CoA levels, causing malonylation (a post-translational modification) of mTOR at lysine 1218 (K1218). mTOR K-1218 malonylation impaired mTOR complex 1 (mTORC1) kinase activity, thereby reducing phosphorylation of downstream targets (p70S6K/4EBP1). Silencing acetyl-CoA carboxylase 1 (an enzyme producing malonyl-CoA) normalized malonyl-CoA levels and reactivated mTOR in FASNKD ECs. Mutagenesis unveiled the importance of mTOR K1218 malonylation for angiogenesis. This study unveils a novel role of FASN in metabolite signaling that contributes to explaining the anti-angiogenic effect of FASN blockade.status: publishe