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Background c-Src is a driver oncogene well-known for tumorigenic signaling, but little for metabolic function. Previous reports about c-Src regulation of glucose metabolism prompted us to investigate its function in other nutrient modulation, particularly in lipid metabolism. Methods Oil-red O staining, cell growth assay, and tumor volume measurement were performed to determine lipid amount and growth inhibitory effect of treatments in lung cancer cells and xenograft model. Gene expression was evaluated by immunoblotting and relative RT-PCR. Transcriptional activity of peroxisome proliferator-activated receptor gamma (PPARγ) was assessed by luciferase assay. Reactive oxygen species (ROS) was measured using ROS sensing dye. Oxygen consumption rate was evaluated by Seahorse XF Mito Stress Test. Clinical relevance of candidate proteins was examined using patient samples and public database analysis. Findings Inhibition of Src induced lipolysis and increased intracellular ROS. Src inhibition derepressed PPARγ transcriptional activity leading to induced expression of lipolytic gene fatty acid binding protein (FABP) 4 which accompanies reduced lipid droplets and decreased tumor growth. The reverse correlation of Src and FABP4 was confirmed in pair-matched lung cancer patient samples, and further analysis using public datasets revealed upregulation of lipolytic genes is associated with better prognosis of cancer patients. Interpretation This study provides an insight of how oncogenic factor Src concurrently regulates both cellular signaling pathways and metabolic plasticity to drive cancer progression. Fund National Research Foundation of Korea and Korea Health Industry Development Institute.

Glioblastomas (GBMs) are characterized by four subtypes, proneural (PN), neural, classical, and mesenchymal (MES) GBMs, and they all have distinct activated signaling pathways. Among the subtypes, PN and MES GBMs show mutually exclusive genetic signatures, and the MES phenotype is, in general, believed to be associated with more aggressive features of GBM: tumor recurrence and drug resistance. Therefore, targeting MES GBMs would improve the overall prognosis of patients with fatal tumors. In this study, we propose peroxisome proliferator-activated receptor gamma (PPARγ) as a potential diagnostic and prognostic biomarker as well as therapeutic target for MES GBM; we used multiple approaches to assess PPARγ, including biostatistics analysis and assessment of preclinical studies. First, we found that PPARγ was exclusively expressed in MES glioblastoma stem cells (GSCs), and ligand activation of endogenous PPARγ suppressed cell growth and stemness in MES GSCs. Further in vivo studies involving orthotopic and heterotopic xenograft mouse models confirmed the therapeutic efficacy of targeting PPARγ; compared to control mice, those that received ligand treatment exhibited longer survival as well as decreased tumor burden. Mechanistically, PPARγ activation suppressed proneural–mesenchymal transition (PMT) by inhibiting the STAT3 signaling pathway. Biostatistical analysis using The Cancer Genomics Atlas (TCGA, n = 206) and REMBRANDT (n = 329) revealed that PPARγ upregulation is linked to poor overall survival and disease-free survival of GBM patients. Analysis was performed on prospective (n = 2) and retrospective (n = 6) GBM patient tissues, and we finally confirmed that PPARγ expression was distinctly upregulated in MES GBM. Collectively, this study provides insight into PPARγ as a potential therapeutic target for patients with MES GBM., Brain cancer: Nuclear receptor offers diagnostic and therapeutic target A protein that helps relay signals within tumor cells provides a promising diagnostic biomarker and therapeutic target for the most deadly form of glioblastoma, a brain cancer. A research team in South Korea led by Myung-Jin Park from the Korea Institute of Radiological and Medical Sciences in Seoul and Yangsik Jeong from Yonsei University in Wonju showed that the gene encoding a nuclear receptor protein called PPARγ is exclusively expressed in glioblastoma stem cells taken from patients with the aggressive “mesenchymal” subtype of the disease, but not in stem cells from other glioblastomas with more favorable outcomes. In cell cultures and mouse models, the researchers found that elevated levels of the nuclear receptor promote cancer growth, but activation of PPARγ, either with drugs or by genetic means, has an opposite effect and suppresses tumor proliferation.

The metabolic function of peroxisome proliferator-activated receptor gamma (PPARγ) in lung cancer remains unclear.To determine the relationship of PPARγ on ALDH1A3-induced lipid peroxidation to inhibit lung cancer cell growth.In silico analysis using microarray dataset was performed to screen the positive correlation between PPARγ and all ALDH isoforms. NUBIscan software and ChIP assay were used to identify the binding sites (BSs) of PPARγ on ALDH1A3 promoter. The expression of ALDH1A3 under thiazolidinedione (TZD) treatment was evaluated by QPCR and Western Blot in HBEC and H1993 cell lines. Upon treatment of TZD, colony formation assay was used to check cell growth inhibition and 4-hydroxy-2-nonenal (4HNE) production as lipid peroxidation marker was determined by Western Blot in PPARγ positive cell H1993 and PPARγ negative cell H1299.Compared to other ALDH isoforms, ALDH1A3 showed the highest positive correlation to PPARγ expression. ALDH1A3 upregulated PPARγ expression while PPARγ activation suppressed ALDH1A3. Among 2 potential screened PPARγ response elements, BS 1 and 2 in the promoter of ALDH1A3 gene, PPARγ bound directly to BS2. Ligand activation of PPARγ suppressed mRNA and protein expression of ALDH1A3. Growth inhibition was observed in H1993 (PPARγ positive cell) treated with PPARγ activator and ALDH inhibitor compared to H1299 (PPARγ negative cell). PPARγ activation increased 4HNE which is known to be suppressed by ALDH1A3.ALDH1A3 suppression could be one of PPARγ tumor suppressive function. This study provides a better understanding of the role of PPARγ in lung cancer.

Background/aim Cancer cells are distinct in terms of glutamine dependence. Here we investigated the different susceptibility of glutamine-independent and glutamine-dependent non-small cell lung cancer (NSCLC) to treatment with tumor necrosis factor receptor-associated protein 1 (TRAP1) inhibitor gamitrinib-triphenylphosphonium (G-TPP). Materials and methods Cell viability and proliferation under glutamine deprivation and G-TPP treatment were determined by the MTT and colony-formation assays. Protein and mRNA expression were determined by western blot and quantitative polymerase chain reaction. Colorimetric-based assay was performed to check for glutamine synthetase (GS) activity. Results NSCLC cells showed diverse adaptation under glutamine-depleted condition and were categorized into glutamine-independent and glutamine-dependent cells. Treatment with G-TPP particularly increased GS activity and induced cell death due to energy shortage indicated by phosphorylated AMP-activated protein kinase (AMPK) in glutamine-dependent cells. Conclusion This finding provides better understanding of TRAP1-mediated glutamine metabolism through GS activity, and evidence that TRAP1 could be a promising therapeutic target for glutamine-addicted cancer.

// Ai N.H. Phan 1, 2 , Vu T.A. Vo 1, 2 , Tuyen N.M. Hua 1, 2 , Min-Kyu Kim 1, 2 , Se-Young Jo 3 , Jong-Whan Choi 1 , Hyun-Won Kim 1 , Jaekyoung Son 3 , Young-Ah Suh 3 and Yangsik Jeong 1, 2 1 Department of Biochemistry, Wonju College of Medicine, Yonsei University, Wonju, Gangwon-do, Republic of Korea 2 Department of Global Medical Science, Institute of Lifestyle Medicine, Wonju College of Medicine, Yonsei University, Wonju, Gangwon-do, Republic of Korea 3 Asan Institute for Life Sciences, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Songpa-gu, Republic of Korea Correspondence to: Yangsik Jeong, email: yjeong@yonsei.ac.kr Keywords: PPARγ, sumoylation, lipid metabolism, lung cancer Received: April 18, 2017 Accepted: June 19, 2017 Published: July 31, 2017 ABSTRACT Metabolic reprogramming as a crucial emerging hallmark of cancer is critical for tumor cells to maintain cellular bioenergetics, biosynthesis and reduction/oxidation (REDOX) balance. Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear hormone receptor regulating transcription of diverse gene sets involved in inflammation, metabolism, and suppressing tumor growth. Thiazolidinediones (TZDs), as selective PPARγ ligands, are insulin-sensitizing drugs widely prescribed for type 2 diabetic patients in the clinic. Here, we report that sumoylation of PPARγ couples lipid metabolism to tumor suppressive function of the receptor in lung cancer. We found that ligand activation of PPARγ dramatically induced de novo lipid synthesis as well as fatty acid beta (β)-oxidation in lung cancer both in vitro and in vivo . More importantly, it turns out that PPARγ regulation of lipid metabolism was dependent on sumoylation of PPARγ. Further biochemical analysis revealed that PPARγ-mediated lipid synthesis depletes nicotinamide adenine dinucleotide phosphate (NADPH), consequently resulting in increased mitochondrial reactive oxygen species (ROS) level that subsequently disrupted REDOX balance in lung cancer. Therefore, liganded PPARγ sumoylation is not only critical for cellular lipid metabolism but also induces oxidative stress that contributes to tumor suppressive function of PPARγ. This study provides an important insight of future translational and clinical research into targeting PPARγ regulation of lipid metabolism in lung cancer patients accompanying type 2 diabetes.

Metabolic reprogramming as a crucial emerging hallmark of cancer is critical for tumor cells to maintain cellular bioenergetics, biosynthesis and reduction/oxidation (REDOX) balance. Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear hormone receptor regulating transcription of diverse gene sets involved in inflammation, metabolism, and suppressing tumor growth. Thiazolidinediones (TZDs), as selective PPARγ ligands, are insulin-sensitizing drugs widely prescribed for type 2 diabetic patients in the clinic. Here, we report that sumoylation of PPARγ couples lipid metabolism to tumor suppressive function of the receptor in lung cancer. We found that ligand activation of PPARγ dramatically induced de novo lipid synthesis as well as fatty acid beta (β)-oxidation in lung cancer both in vitro and in vivo. More importantly, it turns out that PPARγ regulation of lipid metabolism was dependent on sumoylation of PPARγ. Further biochemical analysis revealed that PPARγ-mediated lipid synthesis depletes nicotinamide adenine dinucleotide phosphate (NADPH), consequently resulting in increased mitochondrial reactive oxygen species (ROS) level that subsequently disrupted REDOX balance in lung cancer. Therefore, liganded PPARγ sumoylation is not only critical for cellular lipid metabolism but also induces oxidative stress that contributes to tumor suppressive function of PPARγ. This study provides an important insight of future translational and clinical research into targeting PPARγ regulation of lipid metabolism in lung cancer patients accompanying type 2 diabetes.

Glutamine, a non-essential amino acid, is an important nutrient which is involved in many biochemical pathways such as energy production, macromolecular synthesis, and oxidative stress scavenging. Glutamine metabolism is dysregulated in many cancers which mostly display glutamine addiction for cell proliferation. Thus, glutamine metabolism has become a potential target for treating cancer. Here we report that glutamine-dependent cancer cells are more susceptible for inhibiting cell proliferation with inhibitor treatment of Tumor Necrosis Factor Receptor-Associated Protein 1 (TRAP1), a downstream factor of oncogenic c-Myc involved in glutamine metabolism. Using cell proliferation and cell viability assays, we examined growth inhibitory effects of TRAP1 inhibitor, gamitrinib-triphenylphosphonium (G-TPP), on two groups of cell lines, glutamine-deprivation sensitive versus resistant cell lines. Included are cell lines for each group: HCC827 acquired gefitinib resistance and A549 for the sensitive; HuH7 for the resistant group. Glutamine-deprivation sensitive cell lines showed significant growth inhibition with TRAP1 inhibitor treatment while the corresponding resistant group of cell lines showed no growth inhibitory effects in the same treatment condition. This suggests a potential mechanistic connection of TRAP1 to c-Myc regulation in glutamine metabolism. Taken together, this finding provides a better understanding of oncogene-driven glutamine metabolism as well as evidence that TRAP1 is a promising therapeutic target for glutamine addicted cancer cells. Citation Format: Vu T. Vo, Ai N. Phan, Tuyen N. Hua, Yangsik Jeong, Byoung Heon Kang, Hyun-Won Kim, Jong-Whan Choi. Tumor necrosis factor receptor-associated protein 1 (TRAP1) as a potential target for glutamine addicted cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5434. doi:10.1158/1538-7445.AM2017-5434