bims-meluca Biomed News
on Metabolism of non-small cell lung carcinoma
Issue of 2019‒11‒10
nine papers selected by
Cristina Muñoz Pinedo
L’Institut d’Investigació Biomèdica de Bellvitge

  1. Cell Death Differ. 2019 Nov 04.
    Jing YY, Cai FF, Zhang L, Han J, Yang L, Tang F, Li YB, Chang JF, Sun F, Yang XM, Sun FL, Chen S.
      Cancer cells reprogram their energy metabolic system from the mitochondrial oxidative phosphorylation (OXPHOS) pathway to a glucose-dependent aerobic glycolysis pathway. This metabolic reprogramming phenomenon is known as the Warburg effect, a significant hallmark of cancer. However, the detailed mechanisms underlying this event or triggering this reprogramming remain largely unclear. Here, we found that histone H2B monoubiquitination (H2Bub1) negatively regulates the Warburg effect and tumorigenesis in human lung cancer cells (H1299 and A549 cell lines) likely through controlling the expression of multiple mitochondrial respiratory genes, which are essential for OXPHOS. Moreover, our work also suggested that pyruvate kinase M2 (PKM2), the rate-limiting enzyme of glycolysis, can directly interact with H2B in vivo and in vitro and negatively regulate the level of H2Bub1. The inhibition of cell proliferation and nude mice xenograft of human lung cancer cells induced by PKM2 knockdown can be partially rescued through lowering H2Bub1 levels, which indicates that the oncogenic function of PKM2 is achieved, at least partially, through the control of H2Bub1. Furthermore, PKM2 and H2Bub1 levels are negatively correlated in cancer specimens. Therefore, these findings not only provide a novel mechanism triggering the Warburg effect that is mediated through an epigenetic pathway (H2Bub1) but also reveal a novel metabolic regulator (PKM2) for the epigenetic mark H2Bub1. Thus, the PKM2-H2Bub1 axis may become a promising cancer therapeutic target.
  2. Sci Transl Med. 2019 Nov 06. pii: eaaw7852. [Epub ahead of print]11(517):
    Li L, Ng SR, Colón CI, Drapkin BJ, Hsu PP, Li Z, Nabel CS, Lewis CA, Romero R, Mercer KL, Bhutkar A, Phat S, Myers DT, Muzumdar MD, Westcott PMK, Beytagh MC, Farago AF, Vander Heiden MG, Dyson NJ, Jacks T.
      Small cell lung cancer (SCLC) is an aggressive lung cancer subtype with extremely poor prognosis. No targetable genetic driver events have been identified, and the treatment landscape for this disease has remained nearly unchanged for over 30 years. Here, we have taken a CRISPR-based screening approach to identify genetic vulnerabilities in SCLC that may serve as potential therapeutic targets. We used a single-guide RNA (sgRNA) library targeting ~5000 genes deemed to encode "druggable" proteins to perform loss-of-function genetic screens in a panel of cell lines derived from autochthonous genetically engineered mouse models (GEMMs) of SCLC, lung adenocarcinoma (LUAD), and pancreatic ductal adenocarcinoma (PDAC). Cross-cancer analyses allowed us to identify SCLC-selective vulnerabilities. In particular, we observed enhanced sensitivity of SCLC cells toward disruption of the pyrimidine biosynthesis pathway. Pharmacological inhibition of dihydroorotate dehydrogenase (DHODH), a key enzyme in this pathway, reduced the viability of SCLC cells in vitro and strongly suppressed SCLC tumor growth in human patient-derived xenograft (PDX) models and in an autochthonous mouse model. These results indicate that DHODH inhibition may be an approach to treat SCLC.
  3. Front Oncol. 2019 ;9 1053
    Romero-Garcia S, Prado-Garcia H, Valencia-Camargo AD, Alvarez-Pulido A.
      Lactic acidosis, glucose deprivation and hypoxia are conditions frequently found in solid tumors because, among other reasons, tumors switch to Warburg effect and secrete high levels of lactate, which decreases the pH (<6. 9) in the microenvironment. We hypothesized that lung cancer cells consume lactate and induce mitochondrial biogenesis to support survival and proliferation in lactic acidosis with glucose deprivation even under hypoxia. We examined lung adenocarcinoma cell lines (A-427 and A-549), a breast cancer cell line (MCF-7) and non-transformed fibroblasts (MRC-5). Cells were cultured using RPMI-1640 medium with 28 mM lactate varying pH (6.2 or 7.2) under normoxia (atmospheric O2) or hypoxia (2% O2). Cellular growth was followed during 96 h, as well as lactate, glutamine and glutamate levels, which were measured using a biochemical analyzer. The expression levels of monocarboxylate transporters (MCT1 and MCT4) were evaluated by flow cytometry. To evaluate mitochondrial biogenesis, mitochondrial mass was analyzed by flow cytometry and epifluorescence microscopy. Also, mitochondrial DNA (mtDNA) was measured by qPCR. Transcript levels of Nuclear Respiratory Factors (NRF-1 and NRF-2) and Transcription Factor A Mitochondrial (TFAM) were determined using RT-qPCR. The specific growth rate of A-549 and A-427 cells increased in lactic acidosis compared with neutral lactosis, either under normoxia or hypoxia, a phenomenon that was not observed in MRC-5 fibroblasts. Under hypoxia, A-427 and MCF-7 cells did not survive in neutral lactosis but survived in lactic acidosis. Under lactic acidosis, A-427 and MCF-7 cells increased MCT1 levels, reduced MCT4 levels and consumed higher lactate amounts, while A-549 cells consumed glutamine and decreased MCT1 and MCT4 levels with respect to neutral lactosis condition. Lactic acidosis, either under normoxia or hypoxia, increased mitochondrial mass and mtDNA levels compared with neutral lactosis in all tumor cells but not in fibroblasts. A-549 and MCF-7 cells increased levels of NRF-1, NRF-2, and TFAM with respect to MRC-5 cells, whereas A-427 cells upregulated these transcripts under lactic acidosis compared with neutral lactosis. Thus, lung adenocarcinoma cells induce mitochondrial biogenesis to support survival and proliferation in lactic acidosis with glucose deprivation.
    Keywords:  glucose deprivation; glutamine; mitochondrial DNA (mtDNA); mitochondrial mass; monocarboxylate transporter (MCT); nuclear respiratory factor (NRF); tumor growth rate
  4. Mol Cells. 2019 Nov 07.
    Park C, Lee Y, Je S, Chang S, Kim N, Jeong E, Yoon S.
      Oncogenic gain-of-function mutations are clinical biomarkers for most targeted therapies, as well as represent direct targets for drug treatment. Although loss-of-function mutations involving the tumor suppressor gene, STK11 (LKB1) are important in lung cancer progression, STK11 is not the direct target for anticancer agents. We attempted to identify cancer transcriptome signatures associated with STK11 loss-offunction mutations. Several new sensitive and specific gene expression markers (ENO3, TTC39C, LGALS3, and MAML2) were identified using two orthogonal measures, i.e., fold change and odds ratio analyses of transcriptome data from cell lines and tissue samples. Among the markers identified, the ENO3 gene over-expression was found to be the direct consequence of STK11 loss-of-function. Furthermore, the knockdown of ENO3 expression exhibited selective anticancer effect in STK11 mutant cells compared with STK11 wild type (or recovered) cells. These findings suggest that ENO3 -based targeted therapy might be promising for patients with lung cancer harboring STK11 mutations.
    Keywords:  Enolase 3; STK11 loss-offunction mutation; lung adenocarcinoma
  5. Sci Rep. 2019 Nov 07. 9(1): 16212
    Vanhove K, Thomeer M, Derveaux E, Shkedy Z, Owokotomo OE, Adriaensens P, Mesotten L.
      Several studies have demonstrated that the metabolite composition of plasma may indicate the presence of lung cancer. The metabolism of cancer is characterized by an enhanced glucose uptake and glycolysis which is exploited by 18F-FDG positron emission tomography (PET) in the work-up and management of cancer. This study aims to explore relationships between 1H-NMR spectroscopy derived plasma metabolite concentrations and the uptake of labeled glucose (18F-FDG) in lung cancer tissue. PET parameters of interest are standard maximal uptake values (SUVmax), total body metabolic active tumor volumes (MATVWTB) and total body total lesion glycolysis (TLGWTB) values. Patients with high values of these parameters have higher plasma concentrations of N-acetylated glycoproteins which suggest an upregulation of the hexosamines biosynthesis. High MATVWTB and TLGWTB values are associated with higher concentrations of glucose, glycerol, N-acetylated glycoproteins, threonine, aspartate and valine and lower levels of sphingomyelins and phosphatidylcholines appearing at the surface of lipoproteins. These higher concentrations of glucose and non-carbohydrate glucose precursors such as amino acids and glycerol suggests involvement of the gluconeogenesis pathway. The lower plasma concentration of those phospholipids points to a higher need for membrane synthesis. Our results indicate that the metabolic reprogramming in cancer is more complex than the initially described Warburg effect.
  6. Lipids Health Dis. 2019 Nov 04. 18(1): 190
    Wang S, Hu X, Pan Y.
      BACKGROUND: Lipoprotein concentrations have been associated with the major risk of bleeding events. However, whether plasma levels of LDL-C are associated with the risk of biopsy-related endobronchial hemorrhage remain elusive. Therefore, the present study was initiated to investigate the explicit association of low-density lipoprotein cholesterol (LDL-C) with endobronchial biopsy (EBB)-induced refractory hemorrhage in patients with lung cancer.METHODS: This retrospective study included a total of 659 consecutive patients with lung cancer who had undergone EBB at a tertiary hospital between January 2014 and April 2018. Using multiple regression analysis, the association between LDL-C and the risk of EBB-induced refractory hemorrhage was assessed after adjusting for potential confounding factors.
    RESULTS: A significant proportion (13.8%, 91/659) of the patients experienced refractory hemorrhage following EBB. In multivariate regression analysis, higher plasma LDL-C concentrations were associated with increased risk of EBB-induced refractory hemorrhage in patients with lung cancer after adjusting for potential confounders (P < 0.05). Using the lowest quartile of plasma LDL-C as the reference group, the odds ratio (95% confidence interval) of Q2, Q3, and Q4 were 2.32 (1.07, 5.03), 2.37 (0.94, 5.95), and 3.65 (1.16, 11.51), respectively (P for trend < 0.05). Moreover, this association was noticeably more pronounced in male patients with lung cancer in the subgroup analysis (P < 0.05).
    CONCLUSIONS: Plasma LDL-C was positively correlated with the increased risk of EBB-induced refractory hemorrhage in patients with lung cancer; predominantly, the associated risk was more pronounced in male patients with lung cancer.
    Keywords:  Biopsy; Bronchoscopy; Hemorrhage; Low-density lipoprotein cholesterol; Lung cancer
  7. Respir Investig. 2019 Nov 05. pii: S2212-5345(19)30122-4. [Epub ahead of print]
    Mizumura K, Maruoka S, Shimizu T, Gon Y.
      Nuclear factor erythroid 2-related factor (Nrf)2 is a transcription factor that integrates cellular stress signals by directing various transcriptional programs. As an evolutionarily conserved intracellular defense mechanism, Nrf2 and its endogenous inhibitor Kelch-like ECH-associated protein (Keap)1 inhibit oxidative stress in the lung, which is the internal organ that is continuously exposed to the environment. Oxidative stress is implicated in the pathogenesis of various lung diseases including asthma, acute lung injury, chronic obstructive pulmonary disease (COPD), and interstitial lung disease (ILD). Thus, Nrf2 is considered as a potential therapeutic target in lung diseases owing to its antioxidant effect. Nrf2 also plays a complex role in lung cancer, acting as a tumor suppressor and promoter; recent studies have revealed the tumor-promoting effects of Nrf2 in tumors that have undergone malignant transformation. Lung cancer-associated mutations in Keap1 disrupt Keap1-Nrf2 complex formation, resulting in the ubiquitination and degradation of Keap1, and the constitutive activation of Nrf2. In lung cancer cells, persistently high nuclear Nrf2 levels induce the expression of genes that contribute to metabolic reprogramming, and stimulate cell proliferation. In this review, we outlined the major functions of Nrf2, and discussed its importance in pulmonary diseases such as asthma, acute respiratory distress syndrome, and lung cancer. Elucidating the mechanisms through which Nrf2 modulates the initiation and progression of pulmonary diseases can lead to the development of therapeutics specifically targeting this pathway.
    Keywords:  Keap1; Nrf2; Oxidative stress; Respiratory diseases
  8. Ann Transl Med. 2019 Sep;7(18): 442
    Cheng X, Qiu J, Wang S, Yang Y, Guo M, Wang D, Luo Q, Xu L.
      Background: Hypoxia is crucial in the initiation and progression of tumor metastasis. Circular RNAs (CircRNAs) comprise a novel group of non-coding, RNase R resistant and regulatory RNAs which are generated by 'back-splicing' processes. However, the characterization and function of circRNAs in hypoxic cancer cells remain unknown.Methods: High throughput RNA-seq assay was performed in lung adenocarcinoma cells (A549) under either normoxic or hypoxic conditions. Bioinformatic analysis of differentially expressed circRNAs was conducted and their target genes were predicted and partially confirmed.
    Results: Hypoxia increased the expression of hypoxia-inducible factor 1 alpha (HIF-1α) and its downstream genes in A549 cells and enhanced cell migration ability. Comprehensive analysis of global circRNAs expression profiles of A549 identified a total of 558 circRNAs candidates, among which 65 circRNAs were differentially expressed (35 upregulated and 30 downregulated) in hypoxic cancer cells. The difference in their circRNA expressions were compared by computational analysis and circRNA-miRNA networks were constructed. We further characterized one circRNA (hsa_circ_0008193) derived from the FAM120A gene and renamed it as circFAM120A. The expression of circFAM120A, as validated by reverse transcription polymerase chain reaction, was significantly downregulated in both hypoxic A549 and lung cancer tissue from patients with lymph node metastasis. Gene ontology (GO) enrichment analysis and KEGG pathway analysis revealed that circFAM120A may participate in lung cancer development.
    Conclusions: CircRNAs profiles were altered in lung adenocarcinoma under hypoxia and circFAM120A may have the potential to be a new biomarker of lung adenocarcinoma hypoxia.
    Keywords:  Lung cancer; circular RNA; hypoxia; tumor metastasis
  9. Biochem Biophys Res Commun. 2019 Oct 30. pii: S0006-291X(19)32053-4. [Epub ahead of print]
    Chao Y, Shang J, Ji W.
      Obstructive sleep apnea (OSA) is closely associated with cancer progression and cancer-related mortality. N6-methyladenosine (m6A) is involved in the process of intermittent hypoxia (IH) promoting tumor progression. However, it is unclear how m6A regulates the development of lung adenocarcinoma under IH. In this study, we found that ALKBH5 was elevated in lung adenocarcinoma cells and subcutaneous tumors in mice under IH, which was associated with decreased m6A levels in these cells and tissues. Next, we knocked out ALKBH5 in a human lung adenocarcinoma cell line under IH, and we found that the proliferation and invasion of these cells were significantly inhibited. Mechanistic analysis showed that under IH, knockout of ALKBH5 in lung adenocarcinoma cells upregulated the level of m6A in Forkhead box M1 (FOXM1) mRNA and decreased the translation efficiency of FOXM1 mRNA, resulting in downregulation of the FOXM1 protein. The FOXM1 protein is elevated in lung adenocarcinoma cells and subcutaneous tumor tissues of mice under IH. By knocking out FOXM1 in lung adenocarcinoma cells under IH, proliferation and invasion of these cells were inhibited, and overexpression of FOXM1 partially restored the inhibition of growth and invasion of lung adenocarcinoma cells due to ALKBH5 knockout. Collectively, our findings demonstrate that the m6A demethylase ALKBH5 affects the proliferation and invasion of lung adenocarcinoma cells under IH by downregulating m6A modification on FOXM1 mRNA and by promoting FOXM1 expression.
    Keywords:  ALKBH5; FOXM1; Intermittent hypoxia; Lung cancer; Oncogene; m(6)A