Expression of CYP4A1 in U251 Human Glioma Cell Induces Hyperproliferative Phenotype in Vitro and Rapidly Growing Tumors in Vivo

Guo, Austin M.; Sheng, Ju; Scicli, G; Arbab, Ali S.; Lehman, Norman L.; Edwards, Paul; Falck, John R.; Roman, Richard J.; Scicli, A. G.

doi:10.1124/jpet.108.140889

Cited by 42 publications

(47 citation statements)

References 32 publications

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“…EC proliferation was mediated by VEGF, which increases after the stimulation of ECs with 20-HETE (8, 23). 20-HETE not only induces increases in ECs but also in other cells (24). In the present study, we showed in ECs maintained under normal oxygen conditions that 20-HETE causes the upregulation of HIF-1␣.…”

Section: Discussionsupporting

confidence: 64%

20-HETE can act as a nonhypoxic regulator of HIF-1α in human microvascular endothelial cells

Guo

Scicli

Sheng

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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20-HETE increases the expression of VEGF in human dermal microvascular endothelial cells (ECs). Since VEGF is regulated by hypoxia inducible factor (HIF)-1, we studied whether 20-HETE also upregulates HIF-1α using the stable 20-HETE analog 20-hydroxyeicosa-5( Z),14( Z)dienoic acid (WIT003; 1–10 μM) and found that it induced a marked increase in HIF-1α protein levels. The increases in VEGF after the addition of WIT003 preceded the changes in HIF-1α, and the increases in HIF-1α were prevented by a VEGF neutralizing antibody. This suggests that 20-HETE first causes increases in VEGF, which then, in turn, cause the upregulation of HIF-1α. Stimulation with exogenously added VEGF also led to an upregulation of HIF-1α. Incubation with the MEK1/ERK1/2 inhibitor U-0126 (10 μM) completely abolished the increases in VEGF and thus HIF-1α, suggesting the involvement of ERK1/2 activation. The addition of WIT003 resulted in a rapid and sustained increase in superoxide formation. When WIT003 was added in the presence of the nitric oxide (NO) synthase (NOS) inhibitor N-nitro-l-arginine, no changes in superoxide, VEGF, or HIF-1α were observed. This suggests that NOS is responsible for the early changes in superoxide induced by WIT003. Furthermore, WIT003 induced the expression of the NADPH oxidase subunit p47 phox in ECs before the increases in HIF-1α. Incubation with polyethylene glycol-superoxide dismutase (400 U/ml), apocynin (100 μM), diphenylene iodonium (10 μM), or p47 phox downregulation with small interfering (si)RNA all inhibited the increases in HIF-1α expression. This indicates that the early changes in superoxide lead to VEGF increases and thereby NADPH oxidase-dependent superoxide production, which is required for HIF-1α upregulation. We also found that the higher HIF-1α expression induced by WIT003 was accompanied by higher expression of erythropoietin receptor and angiopoietin-2 proteins. These increases were caused by HIF-1α because their levels were markedly decreased by siRNA downregulation of HIF-1α. 20-HETE may be a novel nonhypoxic regulator of HIF-1α and HIF-1α-regulated genes in ECs.

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Section: Discussionsupporting

confidence: 64%

20-HETE can act as a nonhypoxic regulator of HIF-1α in human microvascular endothelial cells

Guo

Scicli

Sheng

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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“…In 2008, U251 glioblastoma cells were genetically altered (transfected with rat CYP4A1 cDNA) to increase the formation of 20-HETE (156). This stimulated tumor cell proliferation in culture.…”

Section: Cytochrome P450-derived Eicosanoids and Cancermentioning

confidence: 99%

Regulation of inflammation in cancer by eicosanoids

Greene

Huang

Serhan

et al. 2011

Prostaglandins & Other Lipid Mediators

270

232

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Inflammation in the tumour microenvironment is now recognized as one of the hallmarks of cancer. Endogenously produced lipid autacoids, locally acting small molecule lipid mediators, play a central role in inflammation and tissue homeostasis, and have recently been implicated in cancer. A well-studied group of autacoid mediators that are the products of arachidonic acid metabolism include: the prostaglandins, leukotrienes, lipoxins and cytochrome P450 (CYP) derived bioactive products. These lipid mediators are collectively referred to as eicosanoids and are generated by distinct enzymatic systems initiated by cyclooxygenase (COX 1 and 2), lipoxygenases (5-LOX, 12-LOX, 15-LOXa, 15-LOXb), and cytochrome P450s, respectively. These pathways are the target of approved drugs for the treatment of inflammation, pain, asthma, allergies, and cardiovascular disorders. Beyond their potent anti-inflammatory and anti-cancer effects, non-steroidal anti-inflammatory drugs (NSAIDs) and COX-2 specific inhibitors have been evaluated in both preclinical tumor models and clinical trials. Eicosanoid biosynthesis and actions can also be directly influenced by nutrients in the diet, as evidenced by the emerging role of omega-3 fatty acids in cancer prevention and treatment. Most research dedicated to using eicosanoids to inhibit tumor-associated inflammation has focused on the COX and LOX pathways. Novel experimental approaches that demonstrate the anti-tumor effects of inhibiting cancer-associated inflammation currently include: eicosanoid receptor antagonism, overexpression of eicosanoid metabolizing enzymes, and the use of endogenous anti-inflammatory lipid mediators. Here we review the actions of eicosanoids on inflammation in the context of tumorigenesis. Eicosanoids may represent a missing link between inflammation and cancer and thus could serve as therapeutic target(s) for inhibiting tumor growth.

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“…In some experiments VSMCs were treated with dinitrochlorobenzene (CDNB) (0.15μM). Concentrations of pharmacological inhibitors used have been shown to be effective and specific (27)(28)(29). …”

Section: Introductionmentioning

confidence: 99%

Endothelial Cells Negatively Modulate Reactive Oxygen Species Generation in Vascular Smooth Muscle Cells

Vokurková

et al. 2009

Hypertension

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Abstract-In intact vessels, endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) act as an integrated system, possibly through reactive oxygen species (ROS). Using a coculture system we tested whether ECs modulate VSMC redox status by regulating activity of NAD(P)H oxidase and antioxidants. VSMC production of O 2 •Ϫ , H 2 O 2 , and NO was assessed using fluoroprobes and amplex-red. NAD(P)H oxidase subunit expression and oxidase activity were determined by Western blotting and chemiluminescence, respectively. Expression of thioredoxin, SOD, growth signaling pathways (PCNA, p21cip1, CDK4, ERK1/2, p38MAPK) was evaluated by immunoblotting. Thioredoxin activity was assessed by the insulin disulfide reduction assay. In cocultured conditions, VSMC ROS production was reduced by Ϸ50% without changes in NAD(P)H oxidase expression/activity versus monoculture (PϽ0.05). This was associated with decreased cell growth (PϽ0.05). Expression of Cu/Zn SOD and thioredoxin was increased in coculture versus monoculture VSMCs (PϽ0.01). Pretreatment of ECs with L-NAME (NOS inhibitor), NS-398 (Cox2 inhibitor), and HET0016 (20-HETE inhibitor) did not influence VSMC ROS formation, whereas CDNB, thioredoxin reductase inhibitor, abolished ROS modulating effects of ECs. These findings indicate that in a coculture system recapitulating intact vessels, ECs negatively regulate ROS production in VSMCs through thioredoxin upregulation. Functionally this is associated with growth inhibition. The modulatory actions of ECs are independent of NOS/NO, Cox2, and HETE and do not involve NAD(P)H oxidase. Our data identify novel mechanisms whereby ECs protect against VSMC oxidative stress, a process that may be important in maintaining vascular integrity.

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Expression of CYP4A1 in U251 Human Glioma Cell Induces Hyperproliferative Phenotype in Vitro and Rapidly Growing Tumors in Vivo

Cited by 42 publications

References 32 publications

20-HETE can act as a nonhypoxic regulator of HIF-1α in human microvascular endothelial cells

20-HETE can act as a nonhypoxic regulator of HIF-1α in human microvascular endothelial cells

Regulation of inflammation in cancer by eicosanoids

Endothelial Cells Negatively Modulate Reactive Oxygen Species Generation in Vascular Smooth Muscle Cells

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