Post-transcriptional regulation of vascular endothelial growth factor: Implications for tumor angiogenesis

Molecular effects of genistein, as a potential anticancer agent, on CXCR-4 and VEGF pathway in acute lymphoblastic leukemia

BACKGROUND

Vascular endothelial growth factor (VEGF) is one of the angiogenic mediators that can be secreted by leukemic cells and plays an important role in tumor invasion and metastasis. Another important agent contributing to the relapse of ALL is C-X-C chemokine receptor type-4 (CXCR-4), expression of this receptor in cancer cells has been related to metastasis. It has been identified that genistein-a soy-derived isoflavonoid-has anti-angiogenesis functions. We aimed to show the effects of this compound on VEGF and CXCR-4 in Acute lymphoblastic leukemia (ALL) cell models.

METHODS AND RESULTS

The cytotoxicity of Genistein was measured using the MTS colorimetric assay. After being treated with Genistein, the expression of VEGF in mRNA and protein levels was measured in MOLT-4 and Jurkat cells. We also used flow cytometry assay to determine the expression of CXCR-4 in cell surfaces. We found that Genistein decreased cell viability in two cell models while was more effective on MOLT-4 cells. After Genistein-treatment, surface expression levels of CXCR-4 were decreased, while VEGF secretion and mRNA expression levels were increased in MOLT-4 and Jurkat cells.

CONCLUSIONS

The results suggest that Genistein may not be a reliable choice for the treatment of ALL; however, this different identified pattern can be useful for the recognition of VEGF and CXCR-4 modulators and thus for planning new treatments for leukemia and other VEGF related disorders.

Neuroprotective effects of SOX5 against ischemic stroke by regulating VEGF/PI3K/AKT pathway

Ischemic stroke is a common clinical cardiovascular disease and often accompanied by central nervous system injury. It often causes paralysis or loss of motor function after central nervous system injury and significantly reduces the patient's quality of life. At present, there is no effective treatment strategy for nerve damage caused by ischemic stroke. Therefore, it is urgently need to explore effective treatment targets. The protein expression of SOX5, VEGF and apoptosis related proteins were measured by western blot. The mRNA expression of SOX5 and VEGF were detected by RT-qPCR. The concentration of S100B and GFAP which are related to nerve damage were detected using ELISA assay. The transcriptional regulation of SOX5 on VEGF was detected using ChIP-PCR and dual luciferase reporter gene assays. The cell apoptosis was measured by TUNEL assay and cell viability was detected by CCK-8 assay. In our study, we found that the expression of SOX5 was significantly reduced when LPS induced apoptosis in PC-12 cells. Overexpression of SOX5 repaired LPS-induced apoptosis. SOX5 promotes VEGF expression as a transcription factor to activate the PI3K/AKT pathway. VEGF also repairs nerve injury and brain tissue injury caused by ischemic stroke. In conclusion, SOX5 transcription regulates the expression of VEGF to activate the PI3K/AKT pathway, which repaired nerve damage caused by ischemic stroke. Therefore, SOX5 could be a new targetto regulate VEGF which can repair nerve injury induced by ischemic stroke.

Reduced FOXM1 Expression Limits Trophoblast Migration and Angiogenesis and Is Associated With Preeclampsia

Trophoblast cells are often compared to highly invasive carcinoma cells due to their capacity to proliferate in hypoxic conditions and to exhibit analogous vascular, proliferative, migratory, and invasive capacities. Thus, genes that are important for tumorigenesis, such as forkhead box M1 ( FOXM1) may also be involved in processes of trophoblast invasion. Indeed, we found Foxm1 protein and messenger RNA (mRNA) levels decreased as gestational age increased in rat's placentae. Accordingly, when mimicking early placental events in vitro, protein and mRNA expression of FOXM1 increased from 21% to 8% O₂, reaching its highest expression at 3% oxygen tension, which reflects early implantation environment, and dropping to very low levels at 1% O₂. Remarkably, FOXM1 silencing in JEG-3 cells was able to significantly decrease migration by 27.9%, in comparison with those cells transfected with control siRNA. Moreover, angiogenesis was compromised when conditioned media (CM) from FOXM1-siRNA -JEG-3 (3% O₂) was added to human umbilical vein endothelial cells (HUVEC) cells; however, when CM of JEG-3 cells overexpressing FOXM1 at 1% O₂ was added, the ability of HUVEC to form tubule networks was restored. Additionally, quantitative real-time polymerase chain reaction (PCR) assays of FOXM1 knockdown and overexpression experiments in JEG-3 cells revealed that the depletion of FOXM1 at 3% O₂ and overexpression of FOXM1 at 1% O₂ led to downregulation and upregulation of vascular endothelial growth factor transcriptional (VEGF) levels, respectively. Conversely, we also observed deregulation of FOXM1 in placentae derived from pregnancies complicated by preeclampsia (PE). Therefore, we demonstrate that FOXM1 may be a new regulatory protein of early placentation processes and that under chronic hypoxic conditions (1% O₂) and in patients with severe PE, its levels decrease.

Immunological hallmarks of cis-DDP-resistant Lewis lung carcinoma cells

PURPOSE

Tumor cell resistance to platinum-based chemotherapeutic agents is one of the major hurdles to successful cancer treatment with these drugs, and is associated with alterations in tumor cell immune evasion and immunomodulatory properties. Immunocyte targeting is considered as a relevant approach to fight drug-resistant cancer. In this study, immunological hallmarks of cis-DDP-resistant Lewis lung carcinoma cells (LLC/R9) were investigated.

METHODS

Immunological features of LLC/R9 cells cultured in vitro in normoxic and hypoxic conditions as well as of those that were grown in vivo were examined. The expression of immunologically relevant genes was evaluated by RT-PCR. Tumor cell susceptibility to the macrophage contact tumoricidal activity and NK-mediated cytolysis was investigated in MTT test. TNF-α-mediated tumor cell apoptosis as well as macrophage phagocytosis, oxidative metabolism, and CD206 expression after the treatment with conditioned media from normoxic and hypoxic tumor cells were studied by flow cytometry. Flow cytometry was also used to characterize dendritic cell maturity.

RESULTS

When growing in vitro, LLC/R9 were characterized by slightly increased immunosuppressive cytokine gene expression. Transition to in vivo growth was associated with the enhancement of transcription of these genes in tumor cells. LLC/R9 cells had lowered sensitivity to contact-dependent macrophage-mediated cytotoxicity and to the TNFα-mediated apoptosis in vitro. Conditioned media from hypoxic LLC/R9 cells stimulated reactive oxygen species generation and CD206 expression in non-sensitized macrophages. Acquisition of drug resistance by LLC/R9 cells was associated with their increased sensitivity to NK-cell-mediated cytolysis. Meanwhile, the treatment of LLCR/9-bearing animals with generated ex vivo and loaded with LLC/R9 cell-lysate dendritic cells (DCs) resulted in profoundly enhanced tumor metastasizing.

CONCLUSION

Decreased sensitivity to macrophage cytolysis, polarizing effect on DCs maturation along with increased susceptibility to NK-cell cytotoxic action promote extensive local growth of chemoresistant LLC/R9 tumors in vivo, but hamper their metastasizing.

Andes Hantavirus-Infection of a 3D Human Lung Tissue Model Reveals a Late Peak in Progeny Virus Production Followed by Increased Levels of Proinflammatory Cytokines and VEGF-A

Andes virus (ANDV) causes hantavirus pulmonary syndrome (HPS), a severe acute disease with a 40% case fatality rate. Humans are infected via inhalation, and the lungs are severely affected during HPS, but little is known regarding the effects of ANDV-infection of the lung. Using a 3-dimensional air-exposed organotypic human lung tissue model, we analyzed progeny virus production and cytokine-responses after ANDV-infection. After a 7–10 day period of low progeny virus production, a sudden peak in progeny virus levels was observed during approximately one week. This peak in ANDV-production coincided in time with activation of innate immune responses, as shown by induction of type I and III interferons and ISG56. After the peak in ANDV production a low, but stable, level of ANDV progeny was observed until 39 days after infection. Compared to uninfected models, ANDV caused long-term elevated levels of eotaxin-1, IL-6, IL-8, IP-10, and VEGF-A that peaked 20–25 days after infection, i.e., after the observed peak in progeny virus production. Notably, eotaxin-1 was only detected in supernatants from infected models. In conclusion, these findings suggest that ANDV replication in lung tissue elicits a late proinflammatory immune response with possible long-term effects on the local lung cytokine milieu. The change from an innate to a proinflammatory response might be important for the transition from initial asymptomatic infection to severe clinical disease, HPS.

Phase 1 Study of Safety, Tolerability, and Pharmacokinetics of PTC299, an Inhibitor of Stress-Regulated Protein Translation

PTC299 is a novel small molecule that specifically blocks the production of protein from selected mRNAs that under certain conditions use noncanonical ribosomal translational pathways. Hypoxia, oncogenic transformation, and viral infections limit normal translation and turn on these noncanonical translation pathways that are sensitive to PTC299. Vascular endothelial cell growth factor (VEGF) is an example of a transcript that is posttranscriptionally regulated. Single doses of PTC299 (0.03 to 3 mg/kg) were administered orally to healthy volunteers in a phase 1 single ascending‐dose study. In a subsequent multiple ascending‐dose study in healthy volunteers, multiple‐dose regimens (0.3 to 1.2 mg/kg twice a day or 1.6 mg/kg 3 times a day for 7 days) were evaluated. PTC299 was well tolerated in these studies. As expected in healthy volunteers, mean plasma VEGF levels did not change. Increases in C_max and AUC of PTC299 were dose‐proportional. The target trough plasma concentration associated with preclinical efficacy was achieved within 7 days at doses of 0.6 mg/kg twice daily and above. These data demonstrate that PTC299 is orally bioavailable and well tolerated and support clinical evaluation of PTC299 in cancer, certain viral infections, or other diseases in which deregulation of translational control is a causal factor.

Measurements of CD34+/CD45-dim Stem Cells Predict Healing of Diabetic Neuropathic Wounds

Management of neuropathic foot ulcers in patients with diabetes (DFUs) has changed little over the past decade, and there is currently no objective method to gauge probability of successful healing. We hypothesized that studies of stem/progenitor cells (SPCs) in the early weeks of standard wound management could predict who will heal within 16 weeks. Blood and debrided wound margins were collected for 8 weeks from 100 patients undergoing weekly evaluations and treatment. SPC number and intracellular content of hypoxia-inducible factors (HIFs) were evaluated by flow cytometry and immunohistochemistry. More SPCs entered the bloodstream in the first 2 weeks of care in patients who healed (n = 37) than in those who did not (n = 63). Logistic regression demonstrated that the number of blood-borne SPCs and the cellular content of HIFs at study entry and the first-week follow-up visit predicted healing. Strong correlations were found among week-to-week assessments of blood-borne SPC HIF factors. We conclude that assays of SPCs during the first weeks of care in patients with DFUs can provide insight into how well wounds will respond and may aid with decisions on the use of adjunctive measures.

The translation initiation factor eIF3i up-regulates vascular endothelial growth factor A, accelerates cell proliferation, and promotes angiogenesis in embryonic development and tumorigenesis

Vascular endothelial growth factor A (VEGFA) is a critical proangiogenic factor that is activated by hypoxia at both the transcriptional and post-transcriptional levels. In hypoxia conditions, stabilized hypoxia-inducible factor 1α (HIF1A) is the key regulator for transcriptional activation of VEGFA. However, the post-transcriptional control of VEGFA expression remains poorly understood. Here, we report that the eukaryotic translation initiation factor 3i (eIF3i) is required for VEGFA protein expression in both normal embryonic and tumorigenic angiogenesis. eIF3i is dynamically expressed in the early stages of zebrafish embryogenesis and in human hepatocellular carcinoma tissues. eIF3i homozygous mutant zebrafish embryos show severe angiogenesis defects and human hepatocellular cancer cells with depletion of eIF3i to induce less angiogenesis in tumor models. Under hypoxia, the HIF1A protein can interact with its binding sequence in the eIF3i promoter and activate eIF3i transcription. The expression of VEGFA, which should rise in hypoxia, is significantly inhibited by eIF3i siRNA treatment. Moreover, eIF3i knockdown did not cause a general translation repression but specifically reduced the translation efficiency of the VEGFA mRNAs. Taken together, our results suggest that eIF3i is induced by HIF1A under hypoxia and controls normal and tumorigenic angiogenesis through regulating VEGFA protein translation.

Intestinal epithelial HuR modulates distinct pathways of proliferation and apoptosis and attenuates small intestinal and colonic tumor development

HuR is a ubiquitous nucleocytoplasmic RNA-binding protein that exerts pleiotropic effects on cell growth and tumorigenesis. In this study, we explored the impact of conditional, tissue-specific genetic deletion of HuR on intestinal growth and tumorigenesis in mice. Mice lacking intestinal expression of HuR (Hur (IKO) mice) displayed reduced levels of cell proliferation in the small intestine and increased sensitivity to doxorubicin-induced acute intestinal injury, as evidenced by decreased villus height and a compensatory shift in proliferating cells. In the context of Apc(min/+) mice, a transgenic model of intestinal tumorigenesis, intestinal deletion of the HuR gene caused a three-fold decrease in tumor burden characterized by reduced proliferation, increased apoptosis, and decreased expression of transcripts encoding antiapoptotic HuR target RNAs. Similarly, Hur(IKO) mice subjected to an inflammatory colon carcinogenesis protocol [azoxymethane and dextran sodium sulfate (AOM-DSS) administration] exhibited a two-fold decrease in tumor burden. Hur(IKO) mice showed no change in ileal Asbt expression, fecal bile acid excretion, or enterohepatic pool size that might explain the phenotype. Moreover, none of the HuR targets identified in Apc(min/+)Hur(IKO) were altered in AOM-DSS-treated Hur(IKO) mice, the latter of which exhibited increased apoptosis of colonic epithelial cells, where elevation of a unique set of HuR-targeted proapoptotic factors was documented. Taken together, our results promote the concept of epithelial HuR as a contextual modifier of proapoptotic gene expression in intestinal cancers, acting independently of bile acid metabolism to promote cancer. In the small intestine, epithelial HuR promotes expression of prosurvival transcripts that support Wnt-dependent tumorigenesis, whereas in the large intestine epithelial HuR indirectly downregulates certain proapoptotic RNAs to attenuate colitis-associated cancer. Cancer Res; 74(18); 5322-35. ©2014 AACR.

Multiple functions of the RNA-binding protein HuR in cancer progression, treatment responses and prognosis

The human embryonic lethal abnormal vision-like protein, HuR, is a member of the Hu family of RNA-binding proteins. Over the past decade, this ubiquitously expressed protein has been extensively investigated in cancer research because it is involved in the regulation of mRNA stability and translation in many cell types. HuR activity and function is associated with its subcellular distribution, transcriptional regulation, translational and post-translational modifications. HuR regulation of target mRNAs is based on the interaction between the three specific domains of HuR protein and one or several U- or AU-rich elements (AREs) in the untranslated region of target mRNAs. A number of cancer-related transcripts containing AREs, including mRNAs for proto-oncogenes, cytokines, growth factors, and invasion factors, have been characterized as HuR targets. It has been proposed that HuR has a central tumorigenic activity by enabling multiple cancer phenotypes. In this review, we comprehensively survey the existing evidence with regard to the diverse functions of HuR in caner development and progression. The current data also suggest that HuR might be a novel and promising therapeutic target and a marker for treatment response and prognostic evaluation.

The role of angiogenic and wound-healing factors after spinal cord injury in mammals

Patients with spinal cord injury (SCI) are permanently paralysed and anaesthetic below the lesion. This morbidity is attributed to the deposition of a dense scar at the injury site, the cellular components of which secrete axon growth inhibitory ligands that prevent severed axons reconnecting with denervated targets. Another complication of SCI is wound cavitation where a fluid filled cyst forms in the peri-lesion neuropil, enlarging over the first few months after injury and causes secondary axonal damage. Wound healing after SCI is accompanied by angiogenesis, which is regulated by angiogenic proteins, produced in response to oxygen deprivation. Necrosis in and about the SCI lesion sites may be suppressed by promoting angiogenesis and the resulting neuropil protection will enhance recovery after SCI. This review addresses the use of angiogenic/wound-healing related proteins including vascular endothelial growth factor, fibroblast growth factor, angiopoietin-1, angiopoietin-2 and transforming growth factor-β to moderate necrosis and axon sparing after SCI, providing a conducive environment for growth essential to functional recovery.

Branched-chain amino acid deficiency stabilizes insulin-induced vascular endothelial growth factor mRNA in hepatocellular carcinoma cells

Abnormal sugar metabolism is closely related to chronic liver diseases, including hepatocellular carcinoma (HCC). We previously reported that fasting hyperinsulinemia is a poor prognostic factor for HCC patients. A recent large-scale study has shown that long-term administration of branched chain amino acids (BCAA) reduces the risk of HCC development in obese cirrhotic patients who have been diagnosed with diabetes mellitus, although the mechanism by which it does so is unclear. In this study, we analyzed the expression of vascular endothelial growth factor (VEGF) in HepG2 cells under high-insulin culture conditions, and examined the effect of BCAA on VEGF expression. VEGF secretion was significantly increased by 200 nM of insulin under BCAA deficient conditions, but it was repressed by the addition of BCAA. BCAA activated the mTOR pathway and increase HIF-1α expression under high-insulin culture conditions, however quantitative PCR analysis showed that insulin-induced expression of VEGF mRNAs (VEGF121 and VEGF165) decreased 2 h after the addition of BCAA. The half-lives of both VEGF121 and 165 mRNAs were shortened in the presence of BCAA compared to the absence of BCAA. Therefore it is thought that BCAA regulate VEGF expression mainly at the post-transcriptional level. We also examined which of the Valine, Leucine, and Isoleucine components of BCAA were essential for VEGF mRNA degradation. All three BCAA components were required for acceleration of insulin-induced VEGF mRNA degradation. These results suggest that administration of BCAA may downregulate VEGF expression in patients who have hyperinsulinemia and are in the process of developing HCC.

Endocrine disruptors and human corpus luteum: in vitro effects of phenols on luteal cells function

Endocrine disruptors are well known to impair fertility. The aim of the present study was to investigate the effects of bisphenol A (BPA) and nonylphenol (p-NP) on human luteal function in vitro. In particular, in luteal cells isolated from 21 human corpora lutea progesterone, prostaglandin (PG) F2α, PGE2 and vascular endothelial growth factor (VEGF) release, as well as VEGF expression were evaluated. BPA and p-NP negatively affected both luteal steroidogenesis and luteotrophic/ luteolytic factors balance, without influencing VEGF mRNA expression. Actually, BPA and p-NP impaired human luteal cells function in vitro, underlining the already suggested correlation between phenols and reproductive failure.

Elevated SP-1 transcription factor expression and activity drives basal and hypoxia-induced vascular endothelial growth factor (VEGF) expression in non-small cell lung cancer

VEGF plays a central role in angiogenesis in cancer. Non-small cell lung cancer (NSCLC) tumors have increased microvascular density, localized hypoxia, and high VEGF expression levels; however, there is a lack of understanding of how oncogenic and tumor microenvironment changes such as hypoxia lead to greater VEGF expression in lung and other cancers. We show that NSCLC cells secreted higher levels of VEGF than normal airway epithelial cells. Actinomycin D inhibited all NSCLC VEGF secretion, and VEGF minimal promoter-luciferase reporter constructs were constitutively active until the last 85 base pairs before the transcription start site containing three SP-1 transcription factor-binding sites; mutation of these VEGF promoter SP-1-binding sites eliminated VEGF promoter activity. Furthermore, dominant negative SP-1, mithramycin A, and SP-1 shRNA decreased VEGF promoter activity, whereas overexpression of SP-1 increased VEGF promoter activity. Chromatin immunoprecipitation assays demonstrated SP-1, p300, and PCA/F histone acetyltransferase binding and histone H4 hyperacetylation at the VEGF promoter in NSCLC cells. Cultured NSCLC cells expressed higher levels of SP-1 protein than normal airway epithelial cells, and double-fluorescence immunohistochemistry showed a strong correlation between SP-1 and VEGF in human NSCLC tumors. In addition, hypoxia-driven VEGF expression in NSCLC cells was SP-1-dependent, with hypoxia increasing SP-1 activity and binding to the VEGF promoter. These studies are the first to demonstrate that overexpression of SP-1 plays a central role in hypoxia-induced VEGF secretion.

Intermedin is overexpressed in hepatocellular carcinoma and regulates cell proliferation and survival

Angiogenesis is one of the hallmarks of tumor growth and metastasis. Identification of tumor angiogenic factors has been a critical component in understanding cancer biology and treatment. Intermedin (IMD) has been reported to promote angiogenesis in a rat ischemic model and human umbilical vascular endothelial cells. Our study sought to determine the role of IMD in human hepatocellular carcinoma tumor progression. High IMD mRNA expression levels were observed in human hepatocellular carcinoma tumors, even in early stage disease, by real-time RT-PCR. Immunohistochemical analysis of hepatocellular carcinoma clinical samples demonstrated that the tumor regions were significantly more immunoreactive for IMD than adjacent benign liver. Inhibition of IMD expression using RNA interference reduced cell proliferation in SK-Hep-1 and SNU-398 cells. Blockage of IMD signaling using either an antagonist peptide or a neutralizing antibody inhibited growth in a dose-dependent manner with concomitant induction of apoptosis, causing cleavage of caspase-8 and downregulation of Gli1 and Bcl2. Conversely, addition of IMD active peptide increased the phosphorylation level of extracellular signal-regulated kinase. Thus, IMD might play an important role in cell proliferation and survival of hepatocellular carcinoma. Our data suggests that IMD is a potential biomarker and therapeutic target for hepatocellular carcinoma.

Abnormal histone methylation is responsible for increased vascular endothelial growth factor 165a secretion from airway smooth muscle cells in asthma

Vascular endothelial growth factor (VEGF), a key angiogenic molecule, is aberrantly expressed in several diseases including asthma where it contributes to bronchial vascular remodeling and chronic inflammation. Asthmatic human airway smooth muscle cells hypersecrete VEGF, but the mechanism is unclear. In this study, we defined the mechanism in human airway smooth muscle cells from nonasthmatic and asthmatic patients. We found that asthmatic cells lacked a repression complex at the VEGF promoter, which was present in nonasthmatic cells. Recruitment of G9A, trimethylation of histone H3 at lysine 9 (H3K9me3), and a resultant decrease in RNA polymerase II at the VEGF promoter was critical to repression of VEGF secretion in nonasthmatic cells. At the asthmatic promoter, H3K9me3 was absent because of failed recruitment of G9a; RNA polymerase II binding, in association with TATA-binding protein-associated factor 1, was increased; H3K4me3 was present; and Sp1 binding was exaggerated and sustained. In contrast, DNA methylation and histone acetylation were similar in asthmatic and nonasthmatic cells. This is the first study, to our knowledge, to show that airway cells in asthma have altered epigenetic regulation of remodeling gene(s). Histone methylation at genes such as VEGF may be an important new therapeutic target.

AUF1/hnRNP D represses expression of VEGF in macrophages

Vascular endothelial growth factor (VEGF) expression is regulated by sequence elements in the 3′ UTR of VEGF mRNA. AUF1/hnRNP D suppresses VEGF 3′ UTR–dependent expression. Peptides with arginine–glycine–glycine motifs derived from AUF1 also suppress VEGF expression.

Vascular endothelial growth factor (VEGF) is a regulator of vascularization in development and is a key growth factor in tissue repair. In disease, VEGF contributes to vascularization of solid tumors and arthritic joints. This study examines the role of the mRNA-binding protein AUF1/heterogeneous nuclear ribonucleoprotein D (AUF1) in VEGF gene expression. We show that overexpression of AUF1 in mouse macrophage-like RAW-264.7 cells suppresses endogenous VEGF protein levels. To study 3′ untranslated region (UTR)–mediated regulation, we introduced the 3′ UTR of VEGF mRNA into a luciferase reporter gene. Coexpression of AUF1 represses VEGF-3′ UTR reporter expression in RAW-264.7 cells and in mouse bone marrow–derived macrophages. The C-terminus of AUF1 contains arginine–glycine–glycine (RGG) repeat motifs that are dimethylated. Deletion of the RGG domain of AUF1 eliminated the repressive effects of AUF1. Surprisingly, expression of an AUF1-RGG peptide reduced endogenous VEGF protein levels and repressed VEGF-3′ UTR reporter activity in RAW-264.7 cells. These findings demonstrate that AUF1 regulates VEGF expression, and this study identifies an RGG peptide that suppresses VEGF gene expression.

Effects of down-regulation of microRNA-23a on TNF-α-induced endothelial cell apoptosis through caspase-dependent pathways

AIMS

Endothelial cell injury induced by inflammatory factors plays a critical role in the pathogenesis of numerous vascular diseases. MicroRNAs are well known to be implicated in cell proliferation and apoptosis in inflammatory responses; however, it remains to be determined whether microRNAs are associated with tumour necrosis factor (TNF)-α-mediated endothelial cell injury. The aim of the present study was to investigate the role of microRNAs in TNF-α-induced endothelial cell apoptosis.

METHODS AND RESULTS

Microarrays were used to analyse the global expression of microRNAs in TNF-α-stimulated human primary endothelial cells. Expression profiles of the microRNAs were verified using qRT-PCR. After TNF-α treatment, 12 miRNAs were dramatically up-regulated and nine were down-regulated. LNA-anti-miR-23a and pre-miR-23a were found to modulate one of the markedly down-regulated miRNAs, miR-23a, which could in turn increase or attenuate TNF-α-induced endothelial cell apoptosis. Bioinformatics analysis suggested that caspase-7 and serine/threonine kinase 4 are potential targets of miR-23a. LNA-anti-miR-23a enhanced but pre-miR-23a inhibited the activation of caspase-7, serine/threonine kinase 4, and its related signalling caspase-3 after TNF-α treatment; however, neither pre-miR-23a nor LNA-anti-miR-23a had an effect on TNF-α-induced Bcl-2 activation.

CONCLUSION

Our results suggest that miR-23a may be involved in TNF-α-induced endothelial cell apoptosis through regulation of the caspase-7 and serine/threonine kinase 4-caspase-3 pathways.

Mechanisms Conferring Resistance to Pro-Apoptotic Cancer Gene Therapy

Recently, we have described a novel approach to the treatment of cancer that employs a series of vectors that encode surface expressed chimeric proteins in which the cytoplasmic death domain of Fas is fused in-frame to the extracellular domain of one of a number of cell surface receptors that recognize and bind various ligands that are differentially expressed within the tumor microenvironment. Although the majority of tumor cells transduced with such vectors are killed in the presence of the corresponding cognate ligand, a small percentage survive and in vivo may go on to repopulate a treated tumor. In order to understand the mechanisms employed by tumors to escape the cytotoxic effects of pro-apoptotic signals triggered via Fas, we isolated a large number of 293 tumor cell clones that survive following transfection with a plasmid vector encoding Flk-1/Fas, a chimeric receptor that induces tumor cell death in the presence of the pro-angiogenic cytokine VEGF. Characterization of Flk-1/Fas-positive clones revealed that while survival can most often be attributed simply to the down-regulation of VEGF ligand expression, in cells that express both receptor and ligand, other proteins involved in the regulation of apoptosis may be targeted. Specifically, a Flk-1/Fas-positive, VEGF-positive clone was identified in which expression of APAF-1 was almost completely abrogated.

Adenovirus-mediated transfer of tris-shRNAs induced apoptosis of nasopharyngeal carcinoma cell in vitro and in vivo

RNA interference (RNAi) is an evolutionary conserved mechanism for specific gene silencing. There are currently numerous cancer therapy clinical trials based on RNAi technology. Using an adenoviral system as a delivery mediator of RNAi, we investigated the therapeutic effects of targeting three genes simultaneously in vitro and in vivo. In this study, we constructed an recombinant adenoviral shRNA expression system as Adv-pEGFP-shVEGF-shTERT-shBcl-xl for multi-genes silencing. Our results showed that the adenoviral vector can achieve above 90% of transfection efficiency and induced obvious apoptosis in CNE-2 cell both in vitro and in vivo compared with targeting the TERT alone or controlled group.

Engineered conformation-dependent VEGF peptide mimics are effective in inhibiting VEGF signaling pathways

Angiogenesis, or formation of new blood vessels, is crucial to cancer tumor growth. Tumor growth, progression, and metastasis are critically influenced by the production of the pro-angiogenic vascular endothelial growth factor (VEGF). Promising anti-angiogenic drugs are currently available; however, their susceptibilities to drug resistance and long term toxicity are serious impediments to their use, thus requiring the development of new therapeutic approaches for safe and effective angiogenic inhibitors. In this work, peptides were designed to mimic the VEGF-binding site to its receptor VEGFR-2. The VEGF conformational peptide mimic, VEGF-P3(CYC), included two artificial cysteine residues, which upon cyclization constrained the peptide in a loop native-like conformation to better mimic the anti-parallel structure of VEGF. The engineered cyclic VEGF mimic peptide demonstrated the highest affinity to VEGFR-2 by surface plasmon resonance assay. The VEGF peptide mimics were evaluated as inhibitors in several in vitro assays in which VEGF-dependent signaling pathways were observed. All VEGF mimics inhibited VEGFR-2 phosphorylation with VEGF-P3(CYC) showing the highest inhibitory effects when compared with unstructured peptides. Additionally, we show in several angiogenic in vitro assays that all the VEGF mimics inhibited endothelial cell proliferation, migration, and network formation with the conformational VEGF-P3 (CYC) being the best. The VEGF-P3(CYC) also caused a significant delay in tumor development in a transgenic model of VEGF(+/-)Neu2-5(+/-). These results indicate that the structure-based design is important for the development of this peptidomimetic and for its anti-angiogenic effects.

Association between expression of embryonic lethal abnormal vision-like protein HuR and cyclooxygenase-2 in oral squamous cell carcinoma

BACKGROUND

Increased cytoplasmic HuR expression has been noted in several cancer types, where it may contribute to the increased cyclooxygenase-2 (COX-2) expression observed during tumorigenesis and metastasis.

METHODS

To assess the correlation between COX-2 and HuR in oral squamous cell carcinoma (OSCC), the expression patterns of HuR and COX-2 were assessed via immunohistochemistry analyses of 103 OSCC samples.

RESULTS

Cytoplasmic HuR expression was significantly associated with COX-2 expression (p < .025) and lymph node metastasis (p < .050) and distant metastasis (p < .025). In multivariate analysis, cytoplasmic HuR expression was identified as an independent prognostic parameter for reduced overall survival. The inhibition of HuR expression by siRNA or leptomycin B (LMB) caused a reduction in the inducibility of COX-2 in oral cancer cells.

CONCLUSION

Our results indicate that the cytoplasmic expression of HuR is associated with COX-2 expression in OSCCs and HuR can regulate COX-2 expression in oral cancer cell lines.

Post-transcriptional control during chronic inflammation and cancer: a focus on AU-rich elements

A considerable number of genes that code for AU-rich mRNAs including cytokines, growth factors, transcriptional factors, and certain receptors are involved in both chronic inflammation and cancer. Overexpression of these genes is affected by aberrations or by prolonged activation of several signaling pathways. AU-rich elements (ARE) are important cis-acting short sequences in the 3'UTR that mediate recognition of an array of RNA-binding proteins and affect mRNA stability and translation. This review addresses the cellular and molecular mechanisms that are common between inflammation and cancer and that also govern ARE-mediated post-transcriptional control. The first part examines the role of the ARE-genes in inflammation and cancer and sequence characteristics of AU-rich elements. The second part addresses the common signaling pathways in inflammation and cancer that regulate the ARE-mediated pathways and how their deregulations affect ARE-gene regulation and disease outcome.

ZFP36L1 is regulated by growth factors and cytokines in keratinocytes and influences their VEGF production

Keratinocyte-derived growth factors and cytokines play an important role in epidermal homeostasis and particularly in cutaneous wound repair. Thus, we analyzed a potential role of the ZFP36/tristetraprolin family of zinc finger proteins, which are targets of these factors, but also regulate their production, in keratinocytes. We show that expression of ZFP36, ZFP36L1, and ZFP36L2 is induced by a broad variety of growth factors and cytokines, and by scratch wounding. Since ZFP36L1 is a modulator of vascular endothelium growth factor (VEGF) mRNA stability, we subsequently used siRNA technology to inhibit ZFP36L1 gene expression. Notably, this treatment resulted in prolonged maintenance of elevated VEGF levels in HaCaT keratinocytes upon epidermal growth factor stimulation of these cells. Taken together, our results suggest an important role of ZFP36L1 in wound healing.

Estrogens and androgens affect human luteal cell function

OBJECTIVE

To evaluate estrogens (Es)--E2, estrone (E1), and estriol--and androgens--T and androstendione (A)-effect on P, prostaglandin (PG) F2α, PGE2, and vascular endothelial growth factor (VEGF) release and on VEGF expression in human luteal cells. To elucidate whether androgens effects were direct or mediated by their conversion in Es, an aromatase inhibitor was used. Finally, the luteal effect of the non-aromatizable dihydrotestosterone was evaluated.

DESIGN

Prospective laboratory study.

SETTING

University hospital.

PATIENT(S)

Corpora lutea (CLs) were obtained from 36 normally menstruating patients in the midluteal phase of the menstrual cycle.

INTERVENTION(S)

The human luteal cells were isolated from CLs and primary cultures were established.

MAIN OUTCOME MEASURE(S)

P and PG release were assayed by enzyme immunoassay; VEGF secretion by ELISA; VEGF messenger RNA (mRNA) expression by real-time polymerase chain reaction (PCR).

RESULT(S)

P and PGF2α secretion were decreased by Es and androgens. The VEGF release was increased by Es and androgens, whereas VEGF mRNA expression was not. The aromatase inhibitor counteracted T and A luteal effects.

CONCLUSION(S)

Both Es and androgens could participate in the regulation of human luteal function. The effect of T and A seems to be mediated by their conversion to Es, whereas for dihydrotestosterone, both direct androgenic and indirect estrogenic luteal effects could coexist.

Understanding and Targeting the Eukaryotic Translation Initiation Factor eIF4E in Head and Neck Cancer

The eukaryotic translation initiation factor eIF4E is elevated in about 30% of human malignancies including HNSCC where its levels correlate with poor prognosis. Here, we discuss the biochemical and molecular underpinnings of the oncogenic potential of eIF4E. Studies in human leukemia specimens, and later in a mouse model of prostate cancer, strongly suggest that cells with elevated eIF4E develop an oncogene dependency to it, making them more sensitive to targeting eIF4E than normal cells. We describe several strategies that have been suggested for eIF4E targeting in the clinic: the use of a small molecule antagonist of eIF4E (ribavirin), siRNA or antisense oligonucleotide strategies, suicide gene therapy, and the use of a tissue-targeting 4EBP fusion peptide. The first clinical trial targeting eIF4E indicates that ribavirin effectively targets eIF4E in poor prognosis leukemia patients and more importantly leads to striking clinical responses including complete and partial remissions. Finally, we discuss the relevance of these findings to HNSCC.

Role and therapeutic potential of VEGF in the nervous system

The development of the nervous and vascular systems constitutes primary events in the evolution of the animal kingdom; the former provides electrical stimuli and coordination, while the latter supplies oxygen and nutrients. Both systems have more in common than originally anticipated. Perhaps the most striking observation is that angiogenic factors, when deregulated, contribute to various neurological disorders, such as neurodegeneration, and might be useful for the treatment of some of these pathologies. The prototypic example of this cross-talk between nerves and vessels is the vascular endothelial growth factor or VEGF. Although originally described as a key angiogenic factor, it is now well established that VEGF also plays a crucial role in the nervous system. We describe the molecular properties of VEGF and its receptors and review the current knowledge of its different functions and therapeutic potential in the nervous system during development, health, disease and in medicine.

MicroRNA-21 protects against the H(2)O(2)-induced injury on cardiac myocytes via its target gene PDCD4

Reactive oxygen species (ROS)-induced cardiac cell injury via expression changes of multiple genes plays a critical role in the pathogenesis of numerous heart diseases. MicroRNAs (miRNAs) comprise a novel class of endogenous, small, noncoding RNAs that negatively regulate about 30% of the genes in a cell via degradation or translational inhibition of their target mRNAs. Currently, the effects of ROS on miRNA expression and the roles of miRNAs in ROS-mediated injury on cardiac myocytes are uncertain. Using quantitative real-time RT-PCR (qRT-PCR), we demonstrated that microRNA-21 (miR-21) was upregulated in cardiac myocytes after treatment with hydrogen peroxide (H(2)O(2)). To determine the potential roles of miRNAs in H(2)O(2)-mediated gene regulation and cellular injury, miR-21 expression was downregulated by miR-21 inhibitor and upregulated by pre-miR-21. H(2)O(2)-induced cardiac cell death and apoptosis were increased by miR-21 inhibitor and was decreased by pre-miR-21. Programmed cell death 4 (PDCD4) that was regulated by miR-21 and was a direct target of miR-21 in cardiac myocytes. Pre-miR-21-mediated protective effect on cardiac myocyte injury was inhibited in H(2)O(2)-treated cardiac cells via adenovirus-mediated overexpression of PDCD4 without miR-21 binding site. Moreover, Activator protein 1 (AP-1) was a downstream signaling molecule of PDCD4 that was involved in miR-21-mediated effect on cardiac myocytes. The results suggest that miR-21 is sensitive to H(2)O(2) stimulation. miR-21 participates in H(2)O(2)-mediated gene regulation and functional modulation in cardiac myocytes. miR-21 might play an essential role in heart diseases related to ROS such as cardiac hypertrophy, heart failure, myocardial infarction, and myocardial ischemia/reperfusion injury.

Involvement of MicroRNAs in hydrogen peroxide-mediated gene regulation and cellular injury response in vascular smooth muscle cells

MicroRNAs (miRNAs) comprise a novel class of endogenous, small, noncoding RNAs that negatively regulate approximately 30% of genes in a cell via degradation or translational inhibition of their target mRNAs. However, the effects of reactive oxygen species (ROS) on miRNA expression and the roles of miRNAs in ROS-mediated gene regulation and biological functions of vascular cells are unclear. Using microarray analysis, we demonstrated that miRNAs are aberrantly expressed in vascular smooth muscle cells (VSMCs) after treatment with hydrogen peroxide (H(2)O(2)). H(2)O(2)-mediated up-regulation of microRNA-21 (miR-21) was further confirmed by quantitative real-time PCR. To determine the potential roles of miRNAs in H(2)O(2)-mediated gene regulation and cellular effects, miR-21 expression was down-regulated by miR-21 inhibitor and up-regulated by pre-miR-21. H(2)O(2)-induced VSMC apoptosis and death were increased by miR-21 inhibitor and decreased by pre-miR-21. Programmed cell death 4(PDCD4) was a direct target of miR-21 that was involved in miR-21-mediated effects on VSMCs. Pre-miR-21-mediated protective effect on VSMC apoptosis and death was blocked via adenovirus-mediated overexpression of PDCD4 without the miR-21 binding site. Moreover, activator protein 1 was a downstream signaling molecule of PDCD4 in miR-21-modulated VSMCs. The results suggest that miRNAs in VSMCs are sensitive to H(2)O(2) stimulation. miRN-21 participates in H(2)O(2)-mediated gene regulation and cellular injury response through PDCD4 and the activator protein 1 pathway. miRNAs might play a role in vascular diseases related to ROS.

Tissue microarray analysis of 560 patients with colorectal adenocarcinoma: high expression of HuR predicts poor survival

The purpose of this study is to characterize the expression of HuR in colorectal carcinoma and determine its correlation with clinical outcome. Differential expression of HuR has been suggested to be of prognostic significance in carcinomas of the ovaries, stomach, and breast. HuR regulates the expression of a variety of proteins critical to carcinogenesis via the pathways of cell-cycle progress, invasion, and metastasis. Increasing evidence suggests that angiogenic pathways are involved. A tissue microarray consisting of tumors from 560 patients with colorectal adenocarcinoma was analyzed for HuR protein expression using a quantitative, automated immunofluorescent microscopy system (AQUA). Clinical data corresponding to each examined specimen collected through an institutional review board (IRB)-approved protocol were analyzed using chi-squared test, Cox regression, and Kaplan-Meier analysis. Median follow-up was 54 months. Along with tumor stage and overall tumor-node-metastasis (TNM) stage, HuR expression was found to be an independent predictor of survival. In patients in the highest quartile of total HuR expression, survival was 22.8 months less than those in the lower quartiles (40.6 versus 63.4 months, p = 0.04). Furthermore, HuR levels correlate positively with expression of vascular endothelial growth factor (VEGF) and CD31, a marker for vascular endothelium. We conclude that expression of high levels of HuR correlates with features of advanced disease and portends poorer survival in patients with colorectal adenocarcinoma. These results further suggest that HuR exerts its tumorigenic effects through VEGF-mediated angiogenesis and may be a novel therapeutic target in colorectal cancer.

Expression of vascular endothelial growth factor-A and mRNA stability factor HuR in human meningiomas

We studied the expression of vascular endothelial growth factor-A (VEGF-A) and mRNA stability factor HuR in 40 supratentorial meningiomas using RT-PCR, ELISA and immunohistochemistry, and analyzed their associations with the clinicopathological characteristics, including microvascular density (MVD), peritumoral brain edema (PTBE), histological subtypes and grades, and the performance of preoperative arterial embolization. Furthermore, we investigated the involvement of HuR in the upregulation of VEGF-A expression using primary meningioma cell cultures. The level of VEGF-A is elevated in meningiomas with PTBE and in higher grade meningiomas. Preoperative arterial embolization did not significantly increase the level of VEGF-A, but it did increase the expression of HuR in tumor tissues. HuR expression was correlated positively with VEGF-A expression in meningioma tissues. In in vitro experiments, hypoxia induced the upregulation of VEGF-A expression and the cytoplasmic translocation of HuR protein in meningioma cells, and inhibition of the cytoplasmic translocation of HuR reduced the upregulation of VEGF-A expression in meningioma cells. These findings suggest that the expression of VEGF-A relates to the development of PTBE with meningiomas and the histological grade, and that HuR is involved in the upregulation of VEGF-A expression in human meningiomas.

Novel regulation of vascular endothelial growth factor-A (VEGF-A) by transforming growth factor (beta)1: requirement for Smads, (beta)-CATENIN, AND GSK3(beta)

Vascular endothelial growth factor (VEGF) is a vital angiogenic effector, regulating key angiogenic processes. Vascular development relies on numerous signaling pathways, of which those induced by transforming growth factor-beta (TGFbeta) are critical. The Wnt/beta-catenin signaling pathway is emerging as necessary for vascular development. Although VEGF, TGFbeta, and Wnt signal transductions are well studied individually, it has not been demonstrated previously that all three can interact or be dependent on each other. We show that regulation of VEGF by TGFbeta(1), in human pulmonary artery smooth muscle cells (PASMCs), depends on a direct interaction between TGFbeta signaling proteins, Smads, and members of the Wnt/beta-catenin signaling family. VEGF promoter reporter constructs identified a region of the VEGF promoter containing two T cell factor (TCF)-binding sites as necessary for TGFbeta(1)-induced VEGF transcription. Mutation of TCF sites and expression of dominant negative TCF4 abolished TGFbeta(1)-induced VEGF promoter activity. Studies in Smad2 and Smad3 knock-out mouse embryonic fibroblasts demonstrated that one or both are required for VEGF regulation by TGFbeta(1), with transfection of dominant negative Smad2 or Smad3 into PASMCs confirming this. Chromatin immunoprecipitation assays showed in cell interactions of Smad2 and Smad3 with TCF4 and beta-catenin at the VEGF promoter, whereas co-immunoprecipitation showed a direct physical interaction between Smad2 and beta-catenin in the nucleus of PASMCs. Finally, we demonstrate that TGFbeta(1) regulates TCF by modifying beta-catenin phosphorylation via regulation of glycogen synthase kinase 3beta. These results provide new insight into the molecular regulation of VEGF by two interacting pathways necessary for vascular development, maintenance, and disease.

Vascular endothelial growth factor in eye disease

Collectively, angiogenic ocular conditions represent the leading cause of irreversible vision loss in developed countries. In the US, for example, retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration are the principal causes of blindness in the infant, working age and elderly populations, respectively. Evidence suggests that vascular endothelial growth factor (VEGF), a 40kDa dimeric glycoprotein, promotes angiogenesis in each of these conditions, making it a highly significant therapeutic target. However, VEGF is pleiotropic, affecting a broad spectrum of endothelial, neuronal and glial behaviors, and confounding the validity of anti-VEGF strategies, particularly under chronic disease conditions. In fact, among other functions VEGF can influence cell proliferation, cell migration, proteolysis, cell survival and vessel permeability in a wide variety of biological contexts. This article will describe the roles played by VEGF in the pathogenesis of retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration. The potential disadvantages of inhibiting VEGF will be discussed, as will the rationales for targeting other VEGF-related modulators of angiogenesis.

Expression of vascular endothelial growth factor-A and mRNA stability factor HuR in human astrocytic tumors

High-grade astrocytic tumors, such as glioblastoma, possess rich vascular components, which are necessary for their growth. VEGF-A is considered to be the major mediator of angiogenesis in malignant neoplasms including high-grade astrocytic tumors. The upregulation of VEGF-A expression in tumor cells is induced by two mechanisms: the transcriptional activation and the post-transcriptional stabilization of VEGF-A mRNA. While the former mechanism mediated by hypoxia inducible factor-1 alpha (HIF-1alpha) has been revealed, the latter mediated by mRNA stability factor HuR remains unclear in astrocytic tumors. In the present study, we investigated the expression of VEGF-A and mRNA stability factor HuR in supratentorial astrocytic tumors of 27 adults using RT-PCR, ELISA, and immunohistochemistry. Furthermore, we studied the involvement of HuR in the upregulation of VEGF-A expression using malignant astrocytoma cell lines. In higher-grade astrocytic tumors, the level of VEGF-A and microvascular density were elevated, cytoplasmic expression of HuR, which potentially means the protection of VEGF-A mRNA from degradation by ribonucleases, appeared, and they were correlated positively. In in vitro experiments, the inhibition of the cytoplasmic translocation of HuR protein by leptomycin B (LMB) reduced the upregulation of VEGF-A expression in malignant astrocytic tumor cells under hypoxic conditions. These findings suggest that the expression of VEGF-A and cytoplasmic translocation of HuR relates to the histological grade, and that HuR is involved in the upregulation of VEGF-A expression, in human astrocytic tumors.

ATF4-dependent transcription is a key mechanism in VEGF up-regulation by oxidized phospholipids: critical role of oxidized sn-2 residues in activation of unfolded protein response

We have shown previously that oxidized phospholipids (OxPLs), known to accumulate in atherosclerotic vessels, stimulate angiogenesis via induction of autocrine mediators, such as vascular endothelial growth factor (VEGF). We now address the pathways mediating up-regulation of VEGF in human endothelial cells treated with OxPLs. Analysis of structure-function relationship using individual species of OxPLs demonstrated a close relation between induction of VEGF and activation of the unfolded protein response (UPR). Inducers of UPR up-regulated VEGF, whereas inhibition of UPR by chemical chaperones or knock-down of cochaperone HTJ-1 inhibited elevation of VEGF mRNA induced by OxPLs. OxPLs induced protein expression of activating transcription factor-4 (ATF4), an important effector of UPR. Expression levels of VEGF in OxPL-treated cells strongly correlated with induction of the ATF4 target genes ATF3 and TRB3. Knocking down ATF4 was paralleled by loss of VEGF induction by OxPLs. Chromatin immunoprecipitation demonstrated that OxPLs stimulated binding of ATF4 to a regulatory site in the VEGFA gene. Taken together, these data characterize UPR and more specifically its ATF4 branch as an important mechanism mediating up-regulation of VEGF by OxPLs, and allow hypothesizing that the UPR cascade might play a role in pathologic angiogenesis in atherosclerotic plaques.

Inhibitory effect of electrolyzed reduced water on tumor angiogenesis

Vascular endothelial growth factor (VEGF) is a key mediator of tumor angiogenesis. Tumor cells are exposed to higher oxidative stress compared to normal cells. Numerous reports have demonstrated that the intracellular redox (oxidation/reduction) state is closely associated with the pattern of VEGF expression. Electrolyzed reduced water (ERW) produced near the cathode during the electrolysis of water scavenged intracellular H(2)O(2) and decreased the release of H(2)O(2) from a human lung adenocarcinoma cell line, A549, and down-regulated both VEGF transcription and protein secretion in a time-dependent manner. To investigate the signal transduction pathway involved in regulating VEGF expression, mitogen-activated kinase (MAPK) specific inhibitors, SB203580 (p38 MAPK inhibitor), PD98059 (ERK1/2 inhibitor) and JNKi (c-Jun N-terminal protein kinase inhibitor) were applied. The results showed that only PD98059 blocks VEGF expression, suggesting an important role for ERK1/2 in regulating VEGF expression in A549 cells. As well, ERW inhibited the activation of extracellular signal-regulated kinase (ERK) in a time-dependent manner. Co-culture experiments to analyze in vitro tubule formation assay revealed that A549 cell-derived conditioned medium significantly stimulated the formation of vascular tubules in all analyzed parameters; tubule total area, tubule junction, number of tubules, and total tubule length. ERW counteracted the effect of A549 cell-conditioned medium and decreased total tube length (p<0.01). The present study demonstrated that ERW down-regulated VEGF gene transcription and protein secretion through inactivation of ERK.

Cancer cell: using inflammation to invade the host

Background

Inflammation is increasingly recognized as an important component of tumorigenesis, although the mechanisms involved are not fully characterized. The invasive capacity of cancers is reflected in the classic metastatic cascade: tumor (T), node (N) and metastasis (M). However, this staging system for cancer would also have a tumoral biological significance.

Presentation of the hypothesis

To integrate the mechanisms that control the inflammatory response in the actual staging system of cancer. It is considered that in both processes of inflammation and cancer, three successive phenotypes are presented that represent the expression of trophic functional systems of increasing metabolic complexity for using oxygen.

Testing the hypothesis

While a malignant tumor develops it express phenotypes that also share the inflammatory response such as: an ischemic phenotype (anoxic-hypoxic), a leukocytic phenotype with anaerobic glycolysis and migration, and an angiogenic phenotype with hyperactivity of glycolytic enzymes, tumor proliferation and metastasis, and cachexia of the host. The increasing metabolic complexity of the tumor cell to use oxygen allows for it to be released, migrate and proliferate, thus creating structures of growing complexity.

Implication of the hypothesis

One aim of cancer gene therapy could be the induction of oxidative phosphorylation, the last metabolic step required by inflammation in order to differentiate the tissue that it produces.