Selective Cytotoxicity of the NAMPT Inhibitor FK866 Toward Gastric Cancer Cells With Markers of the Epithelial-Mesenchymal Transition, Due to Loss of NAPRT.

BACKGROUND & AIMS: Markers of the epithelial-to-mesenchymal transition (EMT) in gastric tumor tissues are associated with poor patient outcomes. We performed a screen to identify pharmacologic compounds that kill gastric cancer cells with EMT-associated gene expression patterns and investigate their mechanisms. METHODS: We identified 29 gastric cancer cell lines with a gene expression signature previously associated with an EMT subtype, based on data from RNA sequence analyses, and confirmed the mesenchymal phenotypes of 7 lines (Hs746T, SNU1750, MKN1, SK4, SNU484, SNU668, and YCC11), based on invasive activity and protein markers. We screened 1,345 compounds for their ability to kill cells with the EMT signature compared with cell lines without this pattern. We tested the effects of identified compounds in BALB/c nude mice bearing GA077 tumors; mice were given intraperitoneal injections of the compound or vehicle (control) twice daily for 24 days and tumor growth was monitored. Proteins associated with the toxicity of the compounds were overexpressed in MKN1 and SNU484 cells or knocked down in MKN45 and SNU719 using small interfering RNAs. We performed immunohistochemical analyses of 942 gastric cancer tissues and investigated associations between EMT markers and protein expression patterns. RESULTS: The nicotinamide phosphoribosyltransferase inhibitor FK866 killed 6 of 7 gastric cancer cell lines with EMT-associated gene expression signatures but not gastric cancer cells without this signature. The 6 EMT-subtype gastric cell lines expressed significantly low levels of nicotinic acid phosphoribosyltransferase (NAPRT), which makes the cells hypersensitive to nicotinamide phosphoribosyltransferase inhibition. Gastric cell lines that expressed higher levels of NAPRT, regardless of EMT markers, were sensitized to FK866 after knockdown of NAPRT, whereas overexpression of NAPRT in deficient EMT cell lines protected them from FK866-mediated toxicity. Administration of FK866 to nude mice with tumors grown from GA077 cells (human gastric cancer tumors of the EMT subtype) led to tumor regression in 2 weeks; FK866 did not affect tumors grown from MKN45 cells without the EMT expression signature. Loss of NAPRT might promote the EMT, because it stabilizes ß-catenin. We correlated the EMT gene expression signature with lower levels of NAPRT in 942 gastric tumors from patients; we also found lower levels of NAPRT mRNA in colorectal, pancreatic, and lung adenocarcinoma tissues with the EMT gene expression signature. CONCLUSIONS: FK866 selectively kills gastric cancer cells with an EMT gene expression signature by inhibiting nicotinamide phosphoribosyltransferase in cells with NAPRT deficiency. Loss of NAPRT expression, frequently through promoter hypermethylation, is observed in many gastric tumors of the EMT subtype. FK866 might be used to treat patients with tumors of this subtype.

Transcriptional profiling upon T cell stimulation reveals down-regulation of inflammatory pathways in T and B cells in SLE versus Sjögren's syndrome.

Systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS) share clinical as well as pathogenic similarities. Although previous studies suggest various abnormalities in different immune cell compartments, dedicated cell-type specific transcriptomic signatures are often masked by patient heterogeneity. Here, we performed transcriptional profiling of isolated CD4, CD8, CD16 and CD19 lymphocytes from pSS and SLE patients upon T cell stimulation, in addition to a steady-state condition directly after blood drawing, in total comprising 581 sequencing samples. T cell stimulation, which induced a pronounced inflammatory response in all four cell types, gave rise to substantial re-modulation of lymphocyte subsets in the two autoimmune diseases compared to healthy controls, far exceeding the transcriptomic differences detected at steady-state. In particular, we detected cell-type and disease-specific down-regulation of a range of pro-inflammatory cytokine and chemokine pathways. Such differences between SLE and pSS patients are instrumental for selective immune targeting by future therapies.

Selective cytotoxicity of a novel mitochondrial complex I inhibitor, YK-135, against EMT-subtype gastric cancer cell lines due to impaired glycolytic capacity.

Epithelial-to-mesenchymal transition (EMT)-subtype gastric cancers have the worst prognosis due to their higher recurrence rate, higher probability of developing metastases and higher chemoresistance compared to those of other molecular subtypes. Pharmacologically actionable somatic mutations are rarely found in EMT-subtype gastric cancers, limiting the utility of targeted therapies. Here, we conducted a high-throughput chemical screen using 37 gastric cancer cell lines and 48,467 synthetic smallmolecule compounds. We identified YK-135, a small-molecule compound that showed higher cytotoxicity toward EMT-subtype gastric cancer cell lines than toward non-EMT-subtype gastric cancer cell lines. YK-135 exerts its cytotoxic effects by inhibiting mitochondrial complex I activity and inducing AMP-activated protein kinase (AMPK)-mediated apoptosis. We found that the lower glycolytic capacity of the EMT-subtype gastric cancer cells confers synthetic lethality to the inhibition of mitochondrial complex I, possibly by failing to maintain energy homeostasis. Other well-known mitochondrial complex I inhibitors (e.g., rotenone and phenformin) mimic the efficacy of YK-135, supporting our results. These findings highlight mitochondrial complex I inhibitors as promising therapeutic agents for EMT-subtype gastric cancers and YK-135 as a novel chemical scaffold for further drug development. [BMB Reports 2022; 55(12): 645-650].

WNK3 inhibition elicits antitumor immunity by suppressing PD-L1 expression on tumor cells and activating T-cell function.

Immune checkpoint therapies, such as programmed cell death ligand 1 (PD-L1) blockade, have shown remarkable clinical benefit in many cancers by restoring the function of exhausted T cells. Hence, the identification of novel PD-L1 regulators and the development of their inhibition strategies have significant therapeutic advantages. Here, we conducted pooled shRNA screening to identify regulators of membrane PD-L1 levels in lung cancer cells targeting druggable genes and cancer drivers. We identified WNK lysine deficient protein kinase 3 (WNK3) as a novel positive regulator of PD-L1 expression. The kinase-dead WNK3 mutant failed to elevate PD-L1 levels, indicating the involvement of its kinase domain in this function. WNK3 perturbation increased cancer cell death in cancer cell-immune cell coculture conditions and boosted the secretion of cytokines and cytolytic enzymes, promoting antitumor activities in CD4+ and CD8+ T cells. WNK463, a pan-WNK inhibitor, enhanced CD8+ T-cell-mediated antitumor activity and suppressed tumor growth as a monotherapy as well as in combination with a low-dose anti-PD-1 antibody in the MC38 syngeneic mouse model. Furthermore, we demonstrated that the c-JUN N-terminal kinase (JNK)/c-JUN pathway underlies WNK3-mediated transcriptional regulation of PD-L1. Our findings highlight that WNK3 inhibition might serve as a potential therapeutic strategy for cancer immunotherapy through its concurrent impact on cancer cells and immune cells.

Mutations and variants of ONECUT1 in diabetes.

Genes involved in distinct diabetes types suggest shared disease mechanisms. Here we show that One Cut Homeobox 1 (ONECUT1) mutations cause monogenic recessive syndromic diabetes in two unrelated patients, characterized by intrauterine growth retardation, pancreas hypoplasia and gallbladder agenesis/hypoplasia, and early-onset diabetes in heterozygous relatives. Heterozygous carriers of rare coding variants of ONECUT1 define a distinctive subgroup of diabetic patients with early-onset, nonautoimmune diabetes, who respond well to diabetes treatment. In addition, common regulatory ONECUT1 variants are associated with multifactorial type 2 diabetes. Directed differentiation of human pluripotent stem cells revealed that loss of ONECUT1 impairs pancreatic progenitor formation and a subsequent endocrine program. Loss of ONECUT1 altered transcription factor binding and enhancer activity and NKX2.2/NKX6.1 expression in pancreatic progenitor cells. Collectively, we demonstrate that ONECUT1 controls a transcriptional and epigenetic machinery regulating endocrine development, involved in a spectrum of diabetes, encompassing monogenic (recessive and dominant) as well as multifactorial inheritance. Our findings highlight the broad contribution of ONECUT1 in diabetes pathogenesis, marking an important step toward precision diabetes medicine.

A Genome-wide Functional Signature Ontology Map and Applications to Natural Product Mechanism of Action Discovery.

Gene expression signature-based inference of functional connectivity within and between genetic perturbations, chemical perturbations, and disease status can lead to the development of actionable hypotheses for gene function, chemical modes of action, and disease treatment strategies. Here, we report a FuSiOn-based genome-wide integration of hypomorphic cellular phenotypes that enables functional annotation of gene network topology, assignment of mechanistic hypotheses to genes of unknown function, and detection of cooperativity among cell regulatory systems. Dovetailing genetic perturbation data with chemical perturbation phenotypes allowed simultaneous generation of mechanism of action hypotheses for thousands of uncharacterized natural products fractions (NPFs). The predicted mechanism of actions span a broad spectrum of cellular mechanisms, many of which are not currently recognized as "druggable." To enable use of FuSiOn as a hypothesis generation resource, all associations and analyses are available within an open source web-based GUI (http://fusion.yuhs.ac).