Fatty acid synthase (FASN), the sole cytosolic mammalian enzyme for de novo lipid synthesis, is crucial for cancer cell survival and associates with poor prognosis. FASN overexpression has been found to cause resistance to genotoxic insults. Here we tested the hypothesis that FASN regulates DNA repair to facilitate survival against genotoxic insults and found that FASN suppresses NF-κB but increases specificity protein 1 (SP1) expression. NF-κB and SP1 bind to a composite element in the poly(ADP-ribose) polymerase 1 (PARP-1) promoter in a mutually exclusive manner and regulate PARP-1 expression. Up-regulation of PARP-1 by FASN in turn increases Ku protein recruitment and DNA repair. Furthermore, lipid deprivation suppresses SP1 expression, which is able to be rescued by palmitate supplementation. However, lipid deprivation or palmitate supplementation has no effect on NF-κB expression. Thus, FASN may regulate NF-κB and SP1 expression using different mechanisms. Altogether, we conclude that FASN regulates cellular response against genotoxic insults by up-regulating PARP-1 and DNA repair via NF-κB and SP1.

IUPUI / Fatty acid synthase (FASN) over-expression has been associated with poor prognosis and recurrence in cancer patients. In addition, it has also been found that overexpression of FASN causes resistance to DNA-damaging treatments by up-regulating the non-homologous end joining (NHEJ) repair of DNA double-strand break. Proton pump inhibitors (PPIs), were originally designed to decrease gastric acid production by binding irreversibly with gastric hydrogen potassium ATPase. PPIs have recently been reported to reduce drug resistance in cancer cells when used in combination with other chemotherapeutics, although the mechanism of resistance reduction is uncertain. In our lab, previous investigation showed that PPIs decreased FASN thioesterase (TE) domain activity and cancer cell proliferation in a dose-dependent manner. In this study, I tested the hypothesis that PPIs sensitize breast cancer cells to doxorubicin and ionizing radiation (IR) treatments by inhibiting FASN. When administered to breast cancer cells as single-agent, lansoprazole exhibited the highest potency in inhibiting both FASN activity and breast cancer cell proliferation, among four PPIs tested. In addition, treatment of breast cancer cells with lansoprazole decreased the mRNA and protein levels of poly (ADP-ribose) polymerase-1 (PARP-1) and NHEJ activity, accompanied by elevated γ-H2AX expression. Following a 3-day treatment with lansoprazole, a dose-dependent disruption in cell cycle disruption and increased apoptosis were also detected. Combination of lansoprazole with either doxorubicin or IR caused profoundly higher levels of DNA damage accumulation than doxorubicin or IR treatment alone, suggesting synergistic effects. Taken together, our observations suggest that PPIs synergistically suppress breast cancer cells in combination with DNA damaging treatments by inhibiting FASN. These findings may provide a potential route to overcome resistance to DNA-damaging chemo/radiation treatments in refractory breast cancers.

Euglena gracilis is a very ancient eukaryote whose chloroplast acquisition and evolution has been independent of higher plants. The organism is unique in possessing two de novo fatty acid synthases, a true multienzyme complex of great size in the cytosol and a plastid-localized type II fatty acid synthase composed of discrete enzymes and acyl carrier protein (ACP). The enzymology of the early steps of fatty acid biosynthesis differed in the Euglena type II fatty acid synthase compared to those of Escherichia coli and plants. The enzymes of Euglena participating in both priming and elongation reactions to form a new carbon-carbon bond were acetyl-CoA-ACP transacylase, malonyl-CoA-ACP transacylase, and β-ketoacyl-ACP synthase I. The effects of inhibitors on the three different enzymes were noted. All carbon-carbon bond formation was inhibited by cerulenin. Although neither fatty acid biosynthesis nor any of the isolated enzymes were sensitive to diisopropylphosphofluoridate, the three Euglena enzymes studied were sensitive to different sulfhydryl-alkylating agents. Acetyl-ACP supported fatty acid biosynthesis as effectively as did comparable amounts of ACPSH and acetyl-CoA. There was no evidence for a β-ketoacyl-ACP synthase III for priming such as has been reported in type II fatty acid synthase of higher plants and bacteria. The roles of the acetyl-CoA-ACP transacylase and β-ketoacyl-ACP synthase I appear to be unique in the type II fatty acid synthase of Euglena. Acetyl-CoA-ACP transacylase, malonyl-CoA-ACP transacylase, and β-ketoacyl-ACP synthase I were separated from one another and shown to have different molecular weights.

Nous avons étudié l’expression et la régulation de la lipogenèse dans les aortes et CMLV et déterminé si elle est modifiée par l’insulino-résistance et le diabète. Les rats Zucker obèses (ZO), diabétiques et Psammomys obesus accumulent plus de lipides dans leurs aortes que leurs contrôles. Cependant l’expression des gènes de la lipogenèse et ceux impliqués dans la captation des acides gras, n’est pas augmentée. Un résultat similaire a été retrouvé dans des pièces d’endartériectomies chez l’homme. Le milieu adipogénique, le glucose ou l’insuline seule stimulent modérément la lipogenèse uniquement dans les CML de Zucker contrôles, aucun effet n’a été observé dans les CML de ZO. Nous avons montré que les effets du TO901317 sur la lipogenèse dans les CMLV sont dus uniquement à l’activation du récepteur nucléaire LXRα, PXR n’a aucun effet. En conclusion, la lipogenèse n’est pas augmentée dans la paroi artérielle durant l’insulino-résistance et le diabète. / We investigated the expression and regulation of lipogenesis in aortas and VSMC and determined if it is modified during metabolic abnormalities. Zucker obese (ZO), diabetic (ZDF) rats, and the high fat diet fed Psammomys obesus accumulated more triglycerides in their aortas than control rats. However the expression of lipogenic genes, or of genes involved in fatty acids uptake, was not increased. Lipogenesis was not increased in human carotid endarterectomy of diabetic compared to non-diabetic patients. The adipogenic medium (ADM), glucose or insulin stimulated moderately lipogenesis but only in VSMC from control rats. No effect was observed in VSMC from ZO. We showed that the lipogenic effects of TO901317observed in VSMC from Zucker control rats are due solely to the nuclear receptor LXRα, PXR agonist had no effect. Conclusion: Lipogenesis is not increased in arterial wall during insulin-resistance and diabetes.

<p>Apoptosis is a conserved mode of cell death executed by a group of proteases named caspases, which collectively ensure tissue homeostasis in multicellular organisms by triggering a program of cellular "suicide" in response to developmental cues or cellular damage. </p><p>Accumulating evidence suggests that cellular metabolism impinges directly upon the decision to initiate cell death. Several links between apoptosis and metabolism have been biochemically characterized. Using <italic>Xenopus</italic> oocyte extracts, our laboratory previously discovered that caspase-2 is suppressed by NADPH metabolism through an inhibitory phosphorylation at S164. However, the physiological relevance of these findings has not been investigated at the whole organism level. Studies presented in this dissertation utilize both Schneider's <italic>Drosophila</italic> S2 (S2) cells and transgenic animals to untangle the influence of metabolic status on fly apoptosis.</p><p>We first demonstrate a novel link between <italic>Drosophila</italic> apoptosis and metabolism by showing that cellular NADPH levels modulate the fly initiator caspase Dronc through its phosphorylation at S130. Biochemically and genetically blocking NADPH production removed this inhibitory phosphorylation, resulting in the activation of Dronc and the subsequent apoptotic cascade in cultured S2 cells and specific neuronal cells in transgenic animals. Similarly, non-phosphorylatable Dronc was found to be more potent than wild-type in triggering neuronal apoptosis. Moreover, upregulation of NADPH prevented Dronc-mediated apoptosis upon abrogation of <italic>Drosophila</italic> Inhibitor of Apoptosis (IAP) protein 1 (DIAP1) by double-stranded RNA (dsRNA) or cycloheximide (CHX) treatment, revealing a novel mechanism of DIAP1-independent apoptotic regulation in <italic>Drosophila</italic>. Mechanistically, the CaMKII-mediated phosphorylation of Dronc hindered its activation, but not its catalytic activity. As NADPH levels have been implicated in the regulation of oocyte death, we demonstrate here that a conserved regulatory circuit also coordinates somatic apoptosis and NADPH levels in <italic>Drosophila</italic>.</p><p>Given the regulatory role of NADPH in the activation of Dronc in <italic>Drosophila</italic> and caspase-2 in vertebrates, we then attempted to further elucidate the underlying signaling pathways. By tracking the catabolic fate of NADPH, we revealed that fatty acid synthase (FASN) activity was required for the metabolic suppression of Dronc, as both the chemical inhibitor orlistat and FASN dsRNA abrogated NADPH-mediated protection against CHX-induced apoptosis in S2 cells. Interestingly, it has been previously demonstrated that blocking FASN induces cell death in numerous cancers, including ovarian cancer; however, the mechanism is still obscure. As our results predict that suppression of FASN activity may prevent the inhibitory phosphorylation of Dronc and caspase 2 (at S130 and S164 respectively), we examined the contribution of caspase-2 to cell death induced by orlistat using ovarian cancer cells. Indeed, caspase-2 S164 was dephosphorylated upon orlistat treatment, initiating the cleavage and activation of caspase-2 and its downstream target, Bid. Knockdown of caspase-2 significantly alleviated orlistat-induced cell death, further illustrating its involvement.</p><p>Lastly, we developed an assay based on bimolecular fluorescence complementation (BiFC) to monitor the oligomerization of Dronc in S2 cells, a crucial step in its activation. The sensitivity of this assay has been validated with several apoptotic stimuli. A future whole-genome screen employing this assay is planned to provide new insights into this complex apoptotic regulatory network by unbiasedly identifying novel apoptotic regulators.</p> / Dissertation

Global studies show the effect of polymorphism of selected genes on dairy production and fatty acid spectrum. The aim of the diploma thesis was genotyping of candidate FASN locus with a focus on milk yield and fatty acid spectrum depending on genotype. The thesis describes the characteristics of cow's milk, milk fat and fatty acids in milk fat. Furthermore, the thesis deals with the genome of cattle and the potential influence of polymorphism of candidate genes affecting fatty acids of milk fat. Genotypes for FASN were determined by the PCR-RFLP method, the milk yield of selected dairy cattle was statistically evaluated according to the milk production indices for 1st lactation in individual breeds, and the determination of fatty acids was performed by spectrophotometry followed by statistical evaluation. The resulting genotypes in selected breeds were only two, the GG genotype with a higher relative frequency than the genotype AG. There is no statistically significant difference between FASN genotypes depending on the milk yield and the fatty acids spectrum.

Conjugated linoleic acids (CLA) have been shown to have remarkable yet inconsistent metabolic effects in mice, rats, hamsters, chickens, cattle, and humans. In particular, effects on lipogenesis vary with tissue, physiological state and specie. In this study we tested the hypothesis that CLA would differentially affect ducks of the same genetic background but of differing age. Growing (7 wk) and maintenance (11 wk) Moulard ducks were grouped by age and fed a standard diet supplemented with either 5% soybean oil (control) or 5% CLA isomer mixture. Animals were harvested after 3 weeks or 6 weeks for assessment of body composition including adipose, liver, viscera, and empty carcass weight. Serum nonesterified fatty acid (NEFA) and glucose concentrations were evaluated, and gene targets were cloned from the duck to use in quantifying mRNA abundance for genes involved in lipogenesis (fatty acid synthase, FAS; acetyl-CoA carboxylase, ACC) and lipid oxidation (carnitine palmitoyl transferase-1, CPT-1) in liver tissue from maintenance animals. After 3 weeks, the growing CLA group exhibited a 24% decrease in dissectible adipose tissue (P < 0.05) while maintenance animals showed no significant diet effect. After 6 weeks, the growing CLA group exhibited a 20% increase in liver mass compared to the control (P < 0.05), but no diet effect on adipose tissue. Maintenance animals receiving dietary CLA had a 42% decrease in adipose tissue mass after 6 weeks, increased serum NEFA, ACC and CPT-1 mRNA after 3 and 6 weeks (P < 0.05), and increased FAS mRNA after 3 weeks of treatment (P < 0.05). These data indicate that CLA have potent effects on lipid metabolism in ducks, but that these effects differ dependent on physiological age.

In-depth characterization has introduced new molecular subtypes of gastric cancer (GC). To identify these, new approaches and techniques are required. Liquid biopsies are trendsetting and provide an easy and feasible method to identify and to monitor GC patients. In a prospective cohort of 87 GC patients, extracellular vesicles (EVs) were isolated from 250 µL of plasma. The total RNA was isolated with TRIZOL. The total RNA amount and the relative mRNA levels of CD44, PTEN, and FASN were measured by qRT-PCR. The isolation of EVs and their contained mRNA was possible in all 87 samples investigated. The relative mRNA levels of PTEN were higher in patients already treated by chemotherapy than in chemo-naïve patients. In patients who had undergone neoadjuvant chemotherapy followed by gastrectomy, a decrease in the total RNA amount was observed after neoadjuvant chemotherapy and gastrectomy, while FASN and CD44 mRNA levels decreased only after gastrectomy. The amount of RNA and the relative mRNA levels of FASN and CD44 in EVs were affected more significantly by chemotherapy and gastrectomy than by chemotherapy alone. Therefore, they are a potential biomarker for monitoring treatment response. Future analyses are needed to identify GC-specific key RNAs in EVs, which could be used for the diagnosis of gastric cancer patients in order to determine their molecular subtype and to accompany the therapeutic response.

A variety of soybean oils (SOs) were developed with improved functional properties. Some of the modified SOs contain altered fatty acid (FA) composition by selective breeding methods. Currently, low α- linolenic acid soybean oil (LLSO) and low α- linolenic acid and mid oleic acid soybean oil (LLMOSO) are available FA modified SOs in the market. The consumption of FA modified SOs has been increased because the United States Food and Drug Administration required listing trans fat content in food products sold in U.S. as an effort to reduce possible health risks caused by trans fat beginning 2006. However, the effects of these FA modified SOs on human chronic diseases including breast cancer (BC) have not been studied. BC has become the most frequently diagnosed cancer and is the second leading cause of cancer death among American women. The type of dietary fat, FA composition, and n-6/n-3 ratio are known to influence BC development. Therefore, it is possible that the changed FA composition and n-6/n-3 ratio in the FA modified SOs may affect BC progression, and its critical health concern needs to be investigated. Increased human epithelial growth factor receptor 2 (Her-2/neu) and fatty acid synthase (FAS) are associated with BC progression. In fact, FAS activity and expression are affected by dietary FA composition and FA metabolism. Hypothesis of this research is that LLSO and LLMOSO may affect Her-2/neu and FAS expressing human BC (SK-Br3) cell growth in vitro and in vivo. To test our hypothesis, we investigated the potential adverse or beneficial effects of LLSO and LLMOSO in comparison with conventional SO and lard on human BC cells and then examined the possible mechanisms of action by evaluating the expression level of genes markers involved in growth factor mediated signal transduction pathway, specifically Her-2/neu PI 3-kinase (phophoinositide 3- kinase)-FAS signal transduction pathway. In vitro study demonstrated that all the tested oils at 0-2 μl/ml level have cytotoxic effects. LLMOSO had less cytotoxic effects on the growth of SK-Br3 cells compared to SO. However, there was no difference in SK-Br3 cell growth between LLSO and SO. The apoptotic protein markers (mutant p53 and caspase-3) analysis revealed that the cell growth inhibition by oil treatments was cytotoxic by triggering apoptosis. Western blot analysis demonstrated that LLSO- and LLMOSO- induced changes on cell growth involve Her-2/neu and FAS signaling transduction pathway and sterol regulatory element binding protein-1 (SREBP-1), mitogen activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI 3-kinase) are possible down-stream effectors of Her-2/neu signaling pathway. We also evaluated the dietary effects of LLSO (20% fat of total calorie), SO (20%), and lard (20%) on the growth of SK-Br3 tumors implanted in athymic mice. Changes in tumor surface area, body weight, and food intake were monitored during the 6 months feeding study. After termination, tumor net weight, Her-2/neu and FAS mRNA expression in tumors, FAS protein expression in liver, lipid composition in diets, abdominal fat, and serum, as well as plasma total cholesterol and triglyceride levels were analyzed. In vivo study showed that there were no statistical differences in tumor size and tumor net weight among SO, LLSO, and lard groups. No differences in FAS mRNA and protein expression levels between the LLSO and SO groups were observed. Tumors from the lard group expressed higher Her-2/neu and FAS mRNA than those from the LLSO and SO group. The lipid analysis demonstrated that LLSO was not significantly distinct from SO in trans fat concentration after metabolism. Serum cholesterol and triglyceride levels were unchanged in LLSO fed compared to SO fed mice. In summary, LLSO which contained modification in αLA concentration showed similar effects on SK-Br3 as SO in both in vitro and in vivo. However, LLMOSO which contained more drastic modifications on FA composition exhibited less cytotoxicity compared to SO in vitro. / Master of Science

The disease malaria afflicts more than a billion people and kills almost one to three million of them every year. Of the four species of Plasmodium affecting man viz., P. falciparum, P. vivax, P. ovale and P. malariae, Plasmodium falciparum is the deadliest as it causes cerebral malaria. The situation has become worse with the continuous emergence of drug resistance in the parasite. Therefore, improving existing drugs and deciphering new pathways for drug development are the need of the hour. The discovery of the type II fatty acid biosynthesis pathway in Plasmodium falciparum (Surolia and Surolia, 2001) has opened up new avenues for the development of new antimalarials as this pathway is entirely different from the human host in which type I pathway exists. Although many biochemical pathways such as the purine, pyrimidine and carbohydrate metabolic pathways, and the phospholipid, folate and heme biosynthetic pathways operate in the malaria parasite and are being investigated for their amenability as antimalarial therapeutic targets, no antimalarial of commercial use based on the direct use of these biochemical pathways as targets has emerged so far. This is due to the fact that the structure and function of the targets of these drugs overlaps with that of the human host. A description of such pathways forms the Chapter 1 of the thesis. This is followed by a description of the discovery and the importance of fatty acid biosynthesis pathway and the available literature on the various enzymes that are targets of potential antimalarials. Three isoforms are known for condensing enzymes - FabH which functions in initiation, and FabB and FabF which function in elongation. These isoforms differ in their biochemical properties and have unique roles to play in deciding the membrane composition of any organism. This aspect is also discussed in this chapter. Cloning and expression of -ketoacyl-ACP synthase, FabB/F from Plasmodium falciparum is described in Chapter 2. PfFabB/F is coded by the nuclear genome and is targeted to the apicoplast. The gene is coded by the locus MAL6P1.165 and the putative amino acid sequence of the protein exists in PlasmoDB. All apicoplast targeted proteins have a characteristic bipartite leader sequence consisting of a signal and a transit peptide sequence (Waller et al., 1998). Since the mature protein start site was not known and none of the software packages could predict the site, I aligned the PfFabB/F sequence with the sequences of other -ketoacyl-ACP synthases. On the basis of similarity with E. coli synthases and the mature protein start site of plant synthases, I cloned the first construct of PfFabB/F. The sequence was amplified by PCR and ligated in pET as well as pGEX vector. Expression in various hosts under different temperature and induction conditions could not solubilize the protein in significant quantities and most of the protein was found in inclusion bodies. Next I expressed the sequence with five more amino acids towards the N-terminal and expressed it as an N- terminal NusA fusion. The protein was purified by single step Ni-NTA affinity chromatography. Along with the full length protein (108 kDa), a truncated version of the protein was also obtained. The identity of the protein was confirmed by western blotting using anti-His antibody and anti-FabB/F antibody. In Chapter 3, the substrate specificity of PfFabB/F has been elucidated. PfFabB/F condenses malonyl-ACP with a range of acyl-ACPs. In vivo, acyl carrier protein (ACP) shuttles the acyl substrates between various enzymes of the fatty acid biosynthesis pathway. Enzymes of the pathway other than synthases can accept substrate analogs like acyl-CoA and acyl-NAC’s also in vitro. Acyl-ACPs are not very stable species and thus are not commercially available. Therefore, they have to be synthesized. Since malonyl-ACP could not be synthesized by chemical means, enzymatic synthesis of acyl-ACPs was done. Acyl-ACP synthetase (Aas) or holo-ACP synthase (ACPS) can be used for enzymatic synthesis. Aas is specific only for longer chain substrates; therefore, I decided to use holo-ACP synthase, an enzyme responsible for converting apo-ACP to holo-ACP in the presence of CoA in vivo (Lambalot and Walsch, 1995). When acyl-CoAs are supplied in place of CoA, acyl-ACP is produced. Malonyl-ACP and acyl-ACPs (C4-C16:1) were thus synthesized using holo-ACP synthase from E. coli. The reaction went to almost 95% completion, indicating broad substrate specificity of this enzyme. Bacterial or plant acyl-ACPs of different chain lengths can be resolved by Conformation Sensitive PAGE (Heath and Rock, 1995, Post- Beittenmiller et al., 1991). However, Pfacyl-ACPs synthesized using ACPS did not show any significant shift on CS-PAGE. Therefore I resorted to MALDI-TOF (Matrix Assisted Laser Desorption and Ionization- Time Of Flight) for monitoring the PfFabB/F condensation reactions. PfFabB/F condensed C4-C12-ACPs with malonyl-ACP to their corresponding -ketoacyl-ACP products, with C6, C8 and C10-ACPs being most readily elongated. C14-ACP was very sluggishly elongated, and C16 and C16:1-ACPs were not elongated at all. The condensation reaction was also followed by autoradiography using14C labeled malonyl-ACP, exploiting the clear mobility shift between malonyl-ACP and the other acyl-ACPs. The inhibitory effect of cerulenin, a known inhibitor of condensing enzymes was also checked. PfFabB/F also exhibited malonyl decarboxylase activity resulting in the production of acetyl-ACP in the absence of any significant condensation activity. All the enzymes of fatty acid synthesis pathway required to complete a cycle were assembled together for the in vitro reconstitution of Plasmodium fatty acid synthesis cycle which is described in Chapter 4. Earlier studies of Surolia & Surolia have shown that C12 and C14 fatty acids are the major constituents of Plasmodium lipids. One of my objectives was to determine the maximum length of the acyl ACP product that is synthesized when all the functionally active enzymes of fatty acid synthesis are put together (Kapoor et. al, 2001, Sharma et al., 2003, Karmodiya and Surolia, 2006). Condensing enzymes have a deterministic role in the fatty acid composition as they catalyze the only irreversible step in fatty acid biosynthesis. By analyzing products of the elongation cycle by mass spectrometry it was apparent that C14-ACP is the longest species formed. As already mentioned, PfFabB/F readily elongates C12-ACP but C14-ACP is weakly elongated. Thus the end product of the Plasmodium FAB pathway is influenced by the substrate specificity of PfFabB/F. This confirms the role of PfFabB/F as a decisive enzyme in determining the length of fatty acids synthesized. The inhibition of the cycle by cerulenin and triclosan is also described in this chapter. Chapter 5 describes the ability of the PffabB/F gene to complement for the mutation of condensing enzymes in CY244 cells (fabBtsfabF-, Yasuno et al., 2004). CY244 cells were transformed with pBAD alone or PfFabB/F cloned in pBAD vector (pBADPffabB/F) and the growth was monitored at non-permissive temperature. The product of PfFabB/F could rescue the growth of mutant cells at high temperature but only in the presence of oleic acid. FabB and FabF are the isoforms of condensing enzymes involved in elongation of the fatty acid synthesis cycle but they have a unique role to play (Garwin et al., 1980). FabB is responsible for unsaturated fatty acid synthesis, and fabB-mutants require oleic acid supplementation for growth. FabF is utilized in temperature regulation of membrane fluidity and E. coli FabF elevates the level of C18:1 or cis-vaccenic acid at lower growth temperature but FabF-mutants have no growth phenotype (Ulrich et al., 1983). Rescue of CY244 cells in the presence of oleic acid supplementation indicated that the PffabB/F gene behaves like FabF and not FabB. Analysis of the fatty acid composition of membrane lipids of CY244 cells transformed with pBAD vector or pBADPffabB/F by GC-MS demonstrated no elevated levels of cis-vaccenic acid in transformed cells. This observation is in agreement with the in vitro determined substrate specificity data which shows that PfFabB/F does not elongate C16:1ACP. The thesis ends with a summary of the findings in Chapter 6 in the context of FabB and FabF enzymes known from other sources. 2, 4, 4’-Trichloro-2’hydroxydiphenylether, commonly known as triclosan, has been used as a topical antibacterial agent for decades. I determined its efficacy in treating acute systemic bacterial infection in mouse model. Triclosan, as compared to other well known antibiotics, could extend the survival time of mice by 48 hours. This work is described in Appendix I. (Sharma et al., 2003)