单细胞测序分析喉癌及其微环境代谢相关靶基因

目的 利用单细胞测序技术寻找喉癌细胞糖酵解和谷氨酰胺代谢相关中小分子靶向药物可能的靶基因。 方法 利用R语言对既往单细胞测序的结果重分析,对细胞进行TSNE分类,对代谢相关基因在喉癌各细胞亚群中的表达进行分析。 结果 喉癌细胞糖酵解过程中可能成为小分子代谢药物作用靶点的基因包括:葡萄糖转运蛋白、己糖激酶、丙酮酸激酶;谷氨酰胺分解代谢中可能成为药物作用的靶基因包括:谷氨酰胺转运蛋白、谷氨酰胺酶、谷氨酸脱氢酶1、苹果酸脱氢酶、乳酸脱氢酶、异柠檬酸脱氢酶2。 结论 喉癌细胞中存在与糖酵解和谷氨酰胺代谢相关的基因靶点,可以作为药物研发的方向。     

Phase 1 Trial of MLN0128 (Sapanisertib) and CB-839 HCl (Telaglenastat) in Patients With Advanced NSCLC (NCI 10327): Rationale and Study Design

IntroductionThere are currently no approved targeted therapies for lung squamous-cell carcinoma (LSCC) and KRAS-mutant lung adenocarcinoma (LUAD). About 30% of LSCC and 25% of KRAS-mutant LUAD exhibit hyperactive NRF2 pathway activation through mutations in NFE2L2 (the gene encoding NRF2) or its negative regulator, KEAP1. Preclinical data demonstrate that these tumors are uniquely sensitive to dual inhibition of glycolysis and glutaminolysis via mammalian target of rapamycin (mTOR) and glutaminase inhibitors. This phase 1 study was designed to assess safety and preliminary activity of the mTOR inhibitor MLN0128 (sapanisertib) in combination with the glutaminase inhibitor CB-839 HCl.MethodsPhase 1 dose finding will use the queue-based variation of the 3 + 3 dose escalation scheme with the primary endpoint of identifying the recommended expansion dose. To confirm the acceptable tolerability of the recommended expansion dose, patients will subsequently enroll onto 1 of 4 expansion cohorts (n = 14 per cohort): (1) LSCC harboring NFE2L2 or (2) KEAP1 mutations, or (3) LUAD harboring KRAS/(KEAP1 or NFE2L2) coalterations, or (4) LSCC wild type for NFE2L2 and KEAP1. The primary endpoint of the dose expansion is to determine the preliminary efficacy of MLN0128/CB-839 combination therapy.ConclusionThis phase 1 study will determine the recommended expansion dose and preliminary efficacy of MLN0128 and CB-839 in advanced non–small-cell lung cancer with a focus on subsets of LSCC and KRAS-mutant LUAD harboring NFE2L2 or KEAP1 mutations.     

Targeting glutamine utilization to block metabolic adaptation of tumor cells under the stress of carboxyamidotriazole-induced nutrients unavailability

Tumor cells have unique metabolic programming that is biologically distinct from that of corresponding normal cells. Resetting tumor metabolic programming is a promising strategy to ameliorate drug resistance and improve the tumor microenvironment. Here, we show that carboxyamidotriazole (CAI), an anticancer drug, can function as a metabolic modulator that decreases glucose and lipid metabolism and increases the dependency of colon cancer cells on glutamine metabolism. CAI suppressed glucose and lipid metabolism utilization, causing inhibition of mitochondrial respiratory chain complex I, thus producing reactive oxygen species (ROS). In parallel, activation of the aryl hydrocarbon receptor (AhR) increased glutamine uptake via the transporter SLC1A5, which could activate the ROS-scavenging enzyme glutathione peroxidase. As a result, combined use of inhibitors of GLS/GDH1, CAI could effectively restrict colorectal cancer (CRC) energy metabolism. These data illuminate a new antitumor mechanism of CAI, suggesting a new strategy for CRC metabolic reprogramming treatment.     

Resistance to BRAF inhibitors induces glutamine dependency in melanoma cells

BRAF inhibitors can extend progression‐free and overall survival in melanoma patients whose tumors harbor mutations in BRAF. However, the majority of patients eventually develop resistance to these drugs. Here we show that BRAF mutant melanoma cells that have developed acquired resistance to BRAF inhibitors display increased oxidative metabolism and increased dependency on mitochondria for survival. Intriguingly, the increased oxidative metabolism is associated with a switch from glucose to glutamine metabolism and an increased dependence on glutamine over glucose for proliferation. We show that the resistant cells are more sensitive to mitochondrial poisons and to inhibitors of glutaminolysis, suggesting that targeting specific metabolic pathways may offer exciting therapeutic opportunities to treat resistant tumors, or to delay emergence of resistance in the first‐line setting.     

Glutamate and asparagine cataplerosis underlie glutamine addiction in melanoma

Glutamine dependence is a prominent feature of cancer metabolism, and here we show that melanoma cells, irrespective of their oncogenic background, depend on glutamine for growth. A quantitative audit of how carbon from glutamine is used showed that TCA-cycle-derived glutamate is, in most melanoma cells, the major glutamine-derived cataplerotic output and product of glutaminolysis. In the absence of glutamine, TCA cycle metabolites were liable to depletion through aminotransferase-mediated α-ketoglutarate-to-glutamate conversion and glutamate secretion. Aspartate was an essential cataplerotic output, as melanoma cells demonstrated a limited capacity to salvage external aspartate. Also, the absence of asparagine increased the glutamine requirement, pointing to vulnerability in the aspartate-asparagine biosynthetic pathway within melanoma metabolism. In contrast to melanoma cells, melanocytes could grow in the absence of glutamine. Melanocytes use more glutamine for protein synthesis rather than secreting it as glutamate and are less prone to loss of glutamate and TCA cycle metabolites when starved of glutamine.     

肿瘤是一种代谢性疾病

肿瘤的生物学本质是什么？是遗传性疾病还是代谢性疾病？这个问题是决定肿瘤治疗方向的重大问题,对这 个问题的认识历史上有过反复。研究发现人类有1,000 种肿瘤相关基因,其中癌基因大约250 种,抑癌基因约700 种, 其中绝大多数在细胞代谢中发挥关键作用,主要涉及 5 条代谢途径：①有氧糖酵解（aerobic glycolysis）、②谷氨酰胺分 解（glutaminolysis）、③一碳代谢（one-carbon metabolism）、④磷酸戊糖通路（pentosephosphate pathway）及⑤脂肪 酸从头合成（de novo synthesize fatty acids）。代谢物组学（metabolomics）及肿瘤代谢产物（oncometabolites）研究发现, 上述 5 条代谢通路使肿瘤细胞由单纯的产生 ATP 转变为产生大量氨基酸、核苷酸、脂肪酸以及细胞快速生长与增殖需要 的其他中间产物,这些代谢产物反过来服务于上述代谢通路,从而促进肿瘤生长、抑制肿瘤凋亡。因此,本文认为肿瘤 是一种代谢性疾病,我们应该据此调整肿瘤的治疗策略与方向,肿瘤营养与代谢调节治疗应该也必将成为肿瘤治疗的主 战场。鉴于肿瘤细胞的高度代谢适应性,遭遇任何应激伤害时会自动切换或启用其他通路,所以肿瘤代谢调节治疗应该 联合阻断或调控多个代谢途径。     

Inhibition of glutamine transporter ASCT2 mitigates bleomycin-induced pulmonary fibrosis in mice

BackgroundIdiopathic pulmonary fibrosis (IPF) represents a fatal pulmonary disease. Its mechanisms remain unclear and effective therapies are urgently needed. Glutaminolysis is involved in IPF pathology, but little is known about the role of ASCT2 responsible for cellular uptake of glutamine in IPF. We investigated the role of ASCT2 and its therapeutic implication in IPF through knockdown of ASCT2 in mice.MethodsMouse IPF model was established through a single intratracheal administration of bleomycin, and lentivirus-coated ASCT2 siRNA was administrated into mice via caudal vein for knockdown of ASCT2. Mouse blood and lung tissues were collected for biochemical, histological, and molecular examinations.ResultsASCT2 siRNA significantly lowered ASCT2 expression in mouse lung tissues. Knockdown of ASCT2 reduced pulmonary levels of glutamic acid, α-ketoglutarate, glutathione and ATP, mitigated pulmonary histological injury, and reduced serum concentrations of pulmonary injury parameters including SP-A, SP-D, KL-6 and CCL18 in IPF mice. Moreover, serum levels of fibrotic parameters HA, LN, PC-III and IV-C were lowered by ASCT2 depletion. Collagen production and pulmonary hydroxyproline levels were also decreased by ASCT2 siRNA in IPF mice, which was concomitant with downregulation of α-smooth muscle actin, collagen type Iα1 and transforming growth factor-β receptor II. Furthermore, ASCT2 deficiency downregulated the mRNA and protein expression of inflammatory cytokines IL-1β and TNF-α as well as macrophage marker F4/80 in lung tissues of IPF mice.ConclusionsInhibition of ASCT2 effectively mitigated pulmonary injury, fibrosis and inflammation in mice with bleomycin-induced IPF. ASCT2 could be a novel therapeutic target for treatment of IPF.     

l-glutamine: a major substrate for tumor cells in vivo?

Summary From 65 human breast cancer xenografts investigated, a net glutamine uptake was found in 13 tumors (mean±SE: 15.7±4.5 nmol/g per min) whereas a net release (22.5±3.3 nmol/g per min) was observed in 40 tumors. In 12 tumors neither a significant net uptake nor a net release was obvious. There is experimental evidence that glutamine is taken up by cancer cells only at arterial concentrations>0.5 mM. Another parameter determining glutamine utilization by tumor cells may be the tissue oxygenation. In hypoxic or anoxic tumor areas, glutamine oxidation is unlikely since oxygen is required for the reoxidation of coenzymes which are reduced in the course of this metabolic pathway. The pronounced net release could be due to proteolysis within the tumors investigated. In ascitic fluid (DS-carcinosarcoma), glutamine accumulated during growth, implicating a reduction in the glutamine consumption rate, proposedly also due to a worsening of the oxygen supply to the suspended tumor cells. Thus, the generally held opinion that l-glutamine is a (if not the) major substrate for the energy metabolism of rapidly growing tumor cells should be reconsidered since evidence for this hypothesis has been derived mainly from in vitro system with abundant oxygen.     

Premature senescence of human endothelial cells induced by inhibition of glutaminase

Cellular senescence is now recognized as an important mechanism of tumor suppression, and the accumulation of senescent cells may contribute to the aging of various human tissues. Alterations of the cellular energy metabolism are considered key events in tumorigenesis and are also known to play an important role for aging processes in lower eukaryotic model systems. In this study, we addressed senescence-associated changes in the energy metabolism of human endothelial cells, using the HUVEC model of in vitro senescence. We observed a drastic reduction in cellular ATP levels in senescent endothelial cells. Although consumption of glucose and production of lactate significantly increased in senescent cells, no correlation was found between both metabolite conversion rates, neither in young endothelial cells nor in the senescent cells, which indicates that glycolysis is not the main energy source in HUVEC. On the other hand, glutamine consumption was increased in senescent HUVEC and inhibition of glutaminolysis by DON, a specific inhibitor of glutaminase, led to a significant reduction in the proliferative capacity of both early passage and late passage cells. Moreover, inhibition of glutaminase activity induced a senescent-like phenotype in young HUVEC within two passages. Together, the data indicate that glutaminolysis is an important energy source in endothelial cells and that alterations in this pathway play a role in endothelial cell senescence.