EXTH-27. MOLECULAR CHARACTERIZATION AND PRECLINICAL DEVELOPMENT OF NOVEL SMALL MOLECULE INHIBITOR SPECIFIC FOR WILD-TYPE IDH1 FOR FERROPTOSIS INDUCTION IN GLIOBLASTOMA

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi169-vi169
Author(s):  
Kevin Murnan ◽  
Serena Tommasini-Ghelfi ◽  
Lisa Hurley ◽  
Corey Dussold ◽  
Daniel Wahl ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Cell Death ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Unsaturated Fatty Acids ◽  
De Novo ◽  
De Novo Lipogenesis ◽  
Therapeutic Modality ◽  
Wild Type ◽  
Genetic Ablation

Abstract Increased de novo synthesis, mobilization and uptake of fatty acids are required to provide sufficient lipids for membrane biogenesis in support of rapid tumor cell division and growth. In addition to their structural roles as components of the plasma membrane, fatty acid-derived lipids regulate ferroptotic cell death, a type of programmed cell death, when oxidized by iron-dependent lipoxygenase enzymes. De novo lipogenesis and the defense against oxidative lipid damage require large amounts of cytosolic NADPH. Our group has recently found that HGG up-regulate wild-type Isocitrate dehydrogenase 1 (referred to hereafter as ‘wt-IDH1high HGG’) to generate large quantities of cytosolic NADPH. RNAi-mediated knockdown of wt-IDH1, alone and in combination with radiation therapy (RT), slows the growth of patient-derived HGG xenografts, while overexpression of wt-IDH1 promotes intracranial HGG growth. Isotope tracer and liquid chromatography-based lipidomic studies indicated that wt-IDH1 supports the de novo biosynthesis of mono-unsaturated fatty acids (MUFAs) and promotes the incorporation of monounsaturated phospholipids into the plasma membrane, while displacing polyunsaturated fatty acid (PUFA) phospholipids. In addition, enhanced NADPH production in wt-IDH1high HGG increases glutathione (GSH) level, reduces reactive oxygen species (ROS), activates the phospholipid peroxidase glutathione peroxidase 4 (GPX4)-driven lipid repair pathway, and dampens the accumulation of PUFA-containing lipid peroxides, known executioners of ferroptosis. To pharmacologically target wt-IDH1,we have used and characterized wt-IDH1i-13, a first-in-class competitive α,β-unsaturated enone (AbbVie). wt-IDH1i-13 potently inhibits wt-IDH1 enzymatic activity, by covalently binding to the NADP+ binding pocket. Our data indicate that wt-IDH1i-13 promotes ferroptosis, which can be rescued by pre-treatment of cells with the peroxyl scavenger and ferroptosis inhibitor ferrostatin. wt-IDH1i-13 is brain-penetrant, and similar to genetic ablation, reduces progression and extends the survival of wt-IDH1high HGG bearing mice, alone and in combination with RT. These studies credential to wt-IDH1i-13 as a novel therapeutic modality for the treatment of wt-IDH1 gliomas.

Regulation Of The Fatty Acid Composition Of Platelet Phospholipids

1981 ◽  
Author(s):  
M L McKean ◽  
J B Smith ◽  
M J Silver
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Unsaturated Fatty Acids ◽  
De Novo ◽  
Membrane Phospholipids ◽  
De Novo Biosynthesis ◽  
Coa Transferase

The fatty acid composition of cell membrane phospholipids does not remain constant after de novo biosynthesis, but undergoes continual remodelling. One of the major routes for remodelling probably includes the deacylation-reacylation steps of the Lands Pathway. This has been shown to be important for the incorporation of long chain, polyunsaturated fatty acids into phospholipids by liver and brain. An understanding of the mechanisms involved in these processes in platelets is especially important in light of the large stores of arachidonic acid (AA) in platelet phospholipids and the role of AA in hemostasis and thrombosis. Previous results from this laboratory have shown that the turnover of radioactive AA, 8,11,14-eicosatrienoic and 5,8,11,14,17-eicosapentaenoic acids in the phospholipids of resting platelets is more rapid than the turnover of radioactive C16 and C18 saturated and unsaturated fatty acids. However, little is known about how fatty acids, especially AA and its homologues, are incorporated into platelet phospholipids during de novo biosynthesis or how they are exchanged during remodelling.At least three enzymes are involved in the deacylation- reacylation of phospholipids: phospholipase A2; acyl CoA synthetase; and acyl CoA transferase. We have studied acyl CoA transferase and have found considerable activity in human platelet membranes. Experiments are in progress to determine the substrate specificity and other properties of this enzyme.

scholarly journals Sterol regulatory element binding protein and dietary lipid regulation of fatty acid synthesis in the mammary epithelium

2010 ◽  
Vol 299 (6) ◽  
pp. E918-E927 ◽  
Author(s):  
Michael C. Rudolph ◽  
Jenifer Monks ◽  
Valerie Burns ◽  
Meridee Phistry ◽  
Russell Marians ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
De Novo ◽  
Regulatory Element ◽  
Acid Synthesis ◽  
De Novo Lipogenesis ◽  
Mrna Levels ◽  
Sterol Regulatory Element

The lactating mammary gland synthesizes large amounts of triglyceride from fatty acids derived from the blood and from de novo lipogenesis. The latter is significantly increased at parturition and decreased when additional dietary fatty acids become available. To begin to understand the molecular regulation of de novo lipogenesis, we tested the hypothesis that the transcription factor sterol regulatory element binding factor (SREBF)-1c is a primary regulator of this system. Expression of Srebf1c mRNA and six of its known target genes increased ≥2.5-fold at parturition. However, Srebf1c-null mice showed only minor deficiencies in lipid synthesis during lactation, possibly due to compensation by Srebf1a expression. To abrogate the function of both isoforms of Srebf1, we bred mice to obtain a mammary epithelial cell-specific deletion of SREBF cleavage-activating protein (SCAP), the SREBF escort protein. These dams showed a significant lactation deficiency, and expression of mRNA for fatty acid synthase ( Fasn), insulin-induced gene 1 ( Insig1), mitochondrial citrate transporter ( Slc25a1), and stearoyl-CoA desaturase 2 ( Scd2) was reduced threefold or more; however, the mRNA levels of acetyl-CoA carboxylase-1α ( Acaca) and ATP citrate lyase ( Acly) were unchanged. Furthermore, a 46% fat diet significantly decreased de novo fatty acid synthesis and reduced the protein levels of ACACA, ACLY, and FASN significantly, with no change in their mRNA levels. These data lead us to conclude that two modes of regulation exist to control fatty acid synthesis in the mammary gland of the lactating mouse: the well-known SREBF1 system and a novel mechanism that acts at the posttranscriptional level in the presence of SCAP deletion and high-fat feeding to alter enzyme protein.

scholarly journals Enterococcus faecalisEncodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Lei Zhu ◽  
Qi Zou ◽  
Xinyun Cao ◽  
John E. Cronan
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Type Strain ◽  
Wild Type Strain ◽  
De Novo ◽  
Acid Synthesis ◽  
Wild Type ◽  
Content Type

ABSTRACTAcyl carrier proteins (ACPs) play essential roles in the synthesis of fatty acids and transfer of long fatty acyl chains into complex lipids. TheEnterococcus faecalisgenome contains two annotatedacpgenes, calledacpAandacpB. AcpA is encoded within the fatty acid synthesis (fab) operon and appears essential. In contrast, AcpB is an atypical ACP, having only 30% residue identity with AcpA, and is not essential. Deletion ofacpBhas no effect onE. faecalisgrowth orde novofatty acid synthesis in media lacking fatty acids. However, unlike the wild-type strain, where growth with oleic acid resulted in almost complete blockage ofde novofatty acid synthesis, theΔacpBstrain largely continuedde novofatty acid synthesis under these conditions. Blockage in the wild-type strain is due to repression offaboperon transcription, leading to levels of fatty acid synthetic proteins (including AcpA) that are insufficient to supportde novosynthesis. Transcription of thefaboperon is regulated by FabT, a repressor protein that binds DNA only when it is bound to an acyl-ACP ligand. Since AcpA is encoded in thefaboperon, its synthesis is blocked when the operon is repressed andacpAthus cannot provide a stable supply of ACP for synthesis of the acyl-ACP ligand required for DNA binding by FabT. In contrast to AcpA,acpBtranscription is unaffected by growth with exogenous fatty acids and thus provides a stable supply of ACP for conversion to the acyl-ACP ligand required for repression by FabT. Indeed,ΔacpBandΔfabTstrains have essentially the samede novofatty acid synthesis phenotype in oleic acid-grown cultures, which argues that neither strain can form the FabT-acyl-ACP repression complex. Finally, acylated derivatives of both AcpB and AcpA were substrates for theE. faecalisenoyl-ACP reductases and forE. faecalisPlsX (acyl-ACP; phosphate acyltransferase).IMPORTANCEAcpB homologs are encoded by many, but not all, lactic acid bacteria (Lactobacillales), including many members of the human microbiome. The mechanisms regulating fatty acid synthesis by exogenous fatty acids play a key role in resistance of these bacteria to those antimicrobials targeted at fatty acid synthesis enzymes. Defective regulation can increase resistance to such inhibitors and also reduce pathogenesis.

Effects of pregnancy and ovarian steroids on fatty acid synthesis and uptake in Syrian hamsters

1991 ◽  
Vol 260 (1) ◽  
pp. R153-R158 ◽  
Author(s):  
A. J. Bhatia ◽  
G. N. Wade
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
White Adipose Tissue ◽  
Fatty Acid Synthesis ◽  
De Novo ◽  
Acid Synthesis ◽  
De Novo Lipogenesis ◽  
Ovarian Steroids ◽  
Syrian Hamsters

The effects of pregnancy and ovarian steroids on the in vivo distribution of newly synthesized fatty acids (incorporation of tritium from 3H2O into fatty acid) in Syrian hamsters (Mesocricetus auratus) were examined. During late, but not early, gestation hamsters had reduced levels of newly synthesized fatty acids in heart, liver, uterus, and white adipose tissues (parametrial and inguinal fat pads). Treatment of ovariectomized hamsters with estradiol + progesterone significantly decreased fatty acid synthesis-uptake in heart, liver, and inguinal white adipose tissue. Treatment with either estradiol or progesterone alone was without significant effect in any tissue. Pretreatment of hamsters with Triton WR-1339 (tyloxapol), an inhibitor of lipoprotein lipase activity and tissue triglyceride uptake, abolished the effects of estradiol + progesterone in white adipose tissue and heart but not in liver. Thus hamsters lose body fat during pregnancy in part because of decreased de novo lipogenesis. The effect of pregnancy on lipogenesis is mimicked by treatment with estradiol + progesterone but not by either hormone alone. Furthermore, it appears that the liver is the principal site of estradiol + progesterone action on lipogenesis in Syrian hamsters.

Abstract 12: Prospective Associations of Fatty Acids in the De Novo Lipogenesis Pathway and Stearoyl CoA-desaturase-1 Activity with Risk of Type 2 Diabetes: the Cardiovascular Health Study

Circulation ◽  
2014 ◽  
Vol 129 (suppl_1) ◽  
Author(s):  
Wenjie Ma ◽  
Jason H Wu ◽  
Qianyi Wang ◽  
Rozenn N Lemaitre ◽  
Kenneth J Mukamal ◽  
...  
Keyword(s):  
Risk Factors ◽  
Fatty Acids ◽  
Fatty Acid ◽  
De Novo ◽  
De Novo Lipogenesis ◽  
Metabolic Risk ◽  
Secondary Analyses ◽  
Stearoyl Coa Desaturase ◽  
Fatty Acid Biomarkers

Background: Experimental evidence suggests de novo lipogenesis (DNL) affects insulin homeostasis via synthesis of saturated (SFA) and monounsaturated fatty acids (MUFA), and also through altered activity of the key regulatory enzyme, Stearoyl-CoA desaturase-1 (SCD-1). Only limited studies have utilized biomarkers of SFA, MUFA and estimated SCD-1 activity to assess their prospective association with risk of type 2 diabetes (T2D). Objective: To investigate the association of 3 major circulating SFA (palmitic acid,16:0, stearic acid,18:0) and MUFA (oleic acid,18:1n-9) in the DNL pathway with metabolic risk factors and incident T2D in a community based cohort of US adults (aged≥65y). In secondary analyses, we assessed relations of other fatty acid biomarkers in the DNL pathway (14:0, 16:1n-7, 16:1n-9, 18:1n-7, and SCD-1 activity estimated by 16:1n-7/16:0 and 18:1n-9/18:0), as well as dietary intake of individual SFA and MUFA with incident T2D. Methods: Among 3060 participants free of T2D and with plasma phospholipid fatty acid measures in 1992 (study baseline), incident T2D cases were identified by medication use assessed annually and repeated blood glucose measures. Usual dietary habits were assessed by repeated FFQs. Associations of fatty acids with metabolic risk factors and incident diabetes were evaluated by multivariate linear regression and Cox proportional models, respectively. Results: During 30,763 person-years of follow-up, 353 incident cases were identified. Higher circulating 16:0 and 18:0 were associated with adverse metabolic profiles including greater BMI, inflammation biomarkers and HOMA-IR (P-trend<0.01 for each), whereas higher 18:1n-9 showed generally beneficial associations (P-trend<0.001 for each). After adjustment for demographic and lifestyle factors, a higher risk of T2D was seen for 16:0 (quintile 5 vs. 1 HR 2.39, 95% CI 1.65-3.46, P-trend<0.001) and 18:0 (HR 1.48, 95% CI 1.04-2.11, P-trend=0.009), but not for 18:1n-9 (HR 0.87, 95% CI 0.59-1.27, P-trend=0.77). In secondary analyses, 16:1n-7 (HR 1.50, 95% CI 1.03-2.20, P-trend=0.03) was positively associated while 18:1n-7 (HR 0.50, 95% CI 0.35-0.72, P-trend<0.001) was inversely associated with risk of T2D. Other fatty acid biomarkers, estimated SCD-1 activity and dietary intake of individual fatty acids, as isocaloric replacement for carbohydrate, were not significantly associated with incident T2D. Conclusion: Circulating levels of 16:0, 18:0 and 16:1n-7 were associated with an increased risk of incident T2D in older adults, whereas 18:1n-7 was associated with lower risk. These results highlight the need for further investigation of biological mechanisms that link specific fatty acids in the DNL pathway to pathogenesis of T2D.

Synthesis of Unsaturated Fatty Acids in Chick Embryo Liver

1971 ◽  
Vol 49 (5) ◽  
pp. 563-567 ◽  
Author(s):  
W. E. Donaldson ◽  
Nancy S. Mueller
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Unsaturated Fatty Acids ◽  
De Novo ◽  
Saturated Fatty Acids ◽  
Acid Synthesis ◽  
Chick Embryos ◽  
Embryo Liver ◽  
Liver Homogenates ◽  
Cyclopropene Fatty Acids

Oxidation, synthesis, and desaturation of fatty acids were assessed in chick embryos and embryonic liver. No differences in the oxidation of palmitate-1-14C and oleate-1-14C by intact embryos and embryo-liver homogenates were found. De novo fatty acid synthesis and microsomal elongation of fatty acids were detected in embryo-liver homogenates, but the activities were low as compared with chick liver. The specific activities of the mitochondrial system of fatty acid elongation were similar in embryo and chick liver. Stimulation of the desaturation of stearic acid was achieved by the substitution of glucose for fatty acids in the culture medium and abolished by the addition of cyclopropene fatty acids to the medium. The hypothesis is advanced that in chick embryos, the rate of desaturation of fatty acids synthesized de novo is less than that of postembryonic liver, and that as a consequence, the liver of embryos cannot maintain the proportion of unsaturated to saturated fatty acids found in yolk.

scholarly journals Pivotal Role of Fatty Acid Synthase in c-MYC Driven Hepatocarcinogenesis

2020 ◽  
Vol 21 (22) ◽  
pp. 8467
Author(s):  
Jiaoyuan Jia ◽  
Li Che ◽  
Antonio Cigliano ◽  
Xue Wang ◽  
Graziella Peitta ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthase ◽  
De Novo ◽  
Liver Tumors ◽  
Cellular Growth ◽  
De Novo Lipogenesis ◽  
Liver Malignancy ◽  
Genetic Ablation

Hepatocellular carcinoma (HCC) is a deadly form of liver malignancy with limited treatment options. Amplification and/or overexpression of c-MYC is one of the most frequent genetic events in human HCC. The mammalian target of Rapamycin Complex 1 (mTORC1) is a major functional axis regulating various aspects of cellular growth and metabolism. Recently, we demonstrated that mTORC1 is necessary for c-Myc driven hepatocarcinogenesis as well as for HCC cell growth in vitro. Among the pivotal downstream effectors of mTORC1, upregulation of Fatty Acid Synthase (FASN) and its mediated de novo lipogenesis is a hallmark of human HCC. Here, we investigated the importance of FASN on c-Myc-dependent hepatocarcinogenesis using in vitro and in vivo approaches. In mouse and human HCC cells, we found that FASN suppression by either gene silencing or soluble inhibitors more effectively suppressed proliferation and induced apoptosis in the presence of high c-MYC expression. In c-Myc/Myeloid cell leukemia 1 (MCL1) mouse liver tumor lesions, FASN expression was markedly upregulated. Most importantly, genetic ablation of Fasn profoundly delayed (without abolishing) c-Myc/MCL1 induced HCC formation. Liver tumors developing in c-Myc/MCL1 mice depleted of Fasn showed a reduction in proliferation and an increase in apoptosis when compared with corresponding lesions from c-Myc/MCL1 mice with an intact Fasn gene. In human HCC samples, a significant correlation between the levels of c-MYC transcriptional activity and the expression of FASN mRNA was detected. Altogether, our study indicates that FASN is an important effector downstream of mTORC1 in c-MYC induced HCC. Targeting FASN may be helpful for the treatment of human HCC, at least in the tumor subset displaying c-MYC amplification or activation.

scholarly journals HepatocyteGHR/STAT5b Signaling Protects Against Liver Injury in NAFLD/NASH Mice Models Independent of Steatosis

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A48-A49
Author(s):  
Mercedes del Río-Moreno ◽  
Mari C Vazquez-Borrego ◽  
Mariyah Mahmood ◽  
Andre Sarmento-Cabral ◽  
Grace Guzman ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Liver Injury ◽  
De Novo ◽  
Corn Oil ◽  
Direct Action ◽  
Liver Weight ◽  
De Novo Lipogenesis ◽  
Wild Type ◽  
Alcoholic Fatty Liver ◽  
Liver Health

Abstract Non-alcoholic fatty liver disease (NAFLD) represents a spectrum of pathologies ranging from simple steatosis to non-alcoholic steatohepatitis (NASH) that can lead to cirrhosis and hepatocellular carcinoma. Clinical and mouse studies indicate GH-signaling is reduced in NAFLD. We reported that chow-fed mice, with adult-onset, hepatocyte-specific GH receptor knockdown (aHepGHRkd) develop steatosis, and with age, a mild NASH-like phenotype. In the present study, we sought to determine if aHepGHRkd accelerates the development of steatosis and fibrosis in the context of diets shown in wild-type male mice, after 6 months of feeding, to produce mild NASH (60% fat [lard] + sucrose in the drinking water [HFS] or a severe NASH-like phenotype (40% fat, with partially hydrogenated corn-oil; 2% cholesterol; 20% fructose [HFCF]). Since aHepGHRkd is associated with a reduction in active STAT5b, aHepGHRkd mice were treated with either a hepatocyte-specific adenoviral-associated vector that expresses constitutively active STAT5b (AAV-TBGp-STAT5bCA = STAT5bCA) or a AAV-Null vector. After only 3 months of feeding either the HFS or HFCF diet, aHepGHRkd, but not GHR-intact controls, mice exhibited clear fibrosis, associated with higher levels of plasma alanine aminotransferase (ALT). STAT5bCA treatment of aHepGHRkd mice reduced fibrosis, as well as plasma ALT. Of note, hepatic TG content did not differ between the treatment groups, within diet. Preliminary studies used GC-MS to reveal aHepGHRkd, in the context of HFS diet, increased hepatic fatty acid ratios indicative of enhanced de novo lipogenesis, while STAT5bCA reversed this effect. These results suggest GHR/STAT5b may protect against liver injury not by controlling absolute fat accumulation, but by modifying the fatty acid composition of hepatic lipids. Finally, in order to determine if STAT5bCA could also reverse established diet-induced NASH, wild-type mice were fed the HFCF diet for 6 months and then treated with AAV-STAT5bCA or AAV-Null vectors, and followed for an additional 3 months. Preliminary findings show STAT5bCA modestly reduced liver weight with no changes in TG content. However, STAT5bCA prevented the rise in plasma ALT observed in Null-treated controls. Of note, some mice developed hepatic tumors, where the number and size of visible tumors was reduced by STAT5bCA. Importantly, in all models examined thus far, changes in the liver phenotype could not be clearly attributed to changes in systemic metabolism, supporting a direct action of GHR/STAT5b signaling on liver health. Taken together, these results suggest that enhancing hepatocyte STAT5b activity could prevent/treat diet-induced NASH. How STAT5b mediates these effects, and if there are other players involved, remains to be elucidated.

Chloroacetamides Affect the Plasma Membrane

2002 ◽  
Vol 57 (9-10) ◽  
pp. 843-852 ◽  
Author(s):  
Bernd Matthes ◽  
Peter Böger
Keyword(s):  
Fatty Acids ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
De Novo ◽  
Fatty Acid Content ◽  
Direct Consequence ◽  
Two Phase ◽  
Phase Partitioning ◽  
Microsomal Membranes ◽  
And Function

In the present study membrane fatty acids were analyzed to find a link between the biosynthesis inhibition of very-long-chain fatty acids and the phytotoxic effects of herbicidal chloroacetamides. Accordingly,we have isolated membranes of cucumber seedlings (Cucumis sativus) by two-phase partitioning and analyzed their fatty acid content. Saturated VLCFAs ranging from C20 to C26 were found in high amounts (22%) in the plasma membrane fraction. Nonmodified VLCFAs were predominantly present in phospholipids, while saturated 2-hydroxylated VLCFAs were identified in cerebrosides. Treatment of intact seedlings with chloroacetamides markedly reduced the VLCFA content in the plasma membrane. This result could be specified by fatty-acid labeling using [14C]malonate as a substrate for fatty acid elongation. De novo incorporation of VLCFAs into the plasma membrane and into microsomal membranes, respectively, was severely impaired by chloroacetamides with I50 values between 10 to 100 nm. These results confirm the previous finding that chloroacetamides inhibit VLCFA biosynthesis localized in the microsomes (Böger et al., Pest Manage. Sci. 56, 497D508, 2000). The direct consequence of this inhibition is a strong decrease of VLCFAs required as constituents of the plasma membrane and the substitution by shorter acyl chains. Apparently, physical properties and function of the plasma membrane are affected eventually leading to death of the plant.

scholarly journals Combination of Mitochondrial and Plasma Membrane Citrate Transporter Inhibitors Inhibits De Novo Lipogenesis Pathway and Triggers Apoptosis in Hepatocellular Carcinoma Cells

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Wan-angkan Poolsri ◽  
Phornpun Phokrai ◽  
Somrudee Suwankulanan ◽  
Narinthorn Phakdeeto ◽  
Pattamaphorn Phunsomboon ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Cancer Therapy ◽  
Cell Apoptosis ◽  
Hepg2 Cells ◽  
Cytotoxic Effect ◽  
De Novo ◽  
De Novo Lipogenesis ◽  
Citrate Transporter

Increased expression levels of both mitochondrial citrate transporter (CTP) and plasma membrane citrate transporter (PMCT) proteins have been found in various cancers. The transported citrates by these two transporter proteins provide acetyl-CoA precursors for the de novo lipogenesis (DNL) pathway to support a high rate of cancer cell viability and development. Inhibition of the DNL pathway promotes cancer cell apoptosis without apparent cytotoxic to normal cells, leading to the representation of selective and powerful targets for cancer therapy. The present study demonstrates that treatments with CTP inhibitor (CTPi), PMCT inhibitor (PMCTi), and the combination of CTPi and PMCTi resulted in decreased cell viability in two hepatocellular carcinoma cell lines (HepG2 and HuH-7). Treatment with citrate transporter inhibitors caused a greater cytotoxic effect in HepG2 cells than in HuH-7 cells. A lower concentration of combined CTPi and PMCTi promotes cytotoxic effect compared with either of a single compound. An increased cell apoptosis and an induced cell cycle arrest in both cell lines were reported after administration of the combined inhibitors. A combination treatment exhibits an enhanced apoptosis through decreased intracellular citrate levels, which consequently cause inhibition of fatty acid production in HepG2 cells. Apoptosis induction through the mitochondrial-dependent pathway was found as a consequence of suppressed carnitine palmitoyl transferase-1 (CPT-1) activity and enhanced ROS generation by combined CTPi and PMCTi treatment. We showed that accumulation of malonyl-CoA did not correlate with decreasing CPT-1 activity. The present study showed that elevated ROS levels served as an inhibition on Bcl-2 activity that is at least in part responsible for apoptosis. Moreover, inhibition of the citrate transporter is selectively cytotoxic to HepG2 cells but not in primary human hepatocytes, supporting citrate-mediating fatty acid synthesis as a promising cancer therapy.

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