Hypoxia inducible factor pathways as targets for functional foods

Altered Adipokine Expression in Tumor Microenvironment Promotes Development of Triple Negative Breast Cancer

Obesity is a remarkably important factor for breast carcinogenesis and aggressiveness. The implication of increased BMI in triple negative breast cancer (TNBC) development is also well established. A malignancy-promoting role of the adipose tissue has been supposed, where the adipocytes that constitute the majority of stromal cells release pro-inflammatory cytokines and growth factors. Alterations in adipokines and their receptors play significant roles in breast cancer initiation, progression, metastasis, and drug response. Classic adipokines, such as leptin, adiponectin, and resistin, have been extensively studied in breast cancer and connected with breast cancer risk and progression. Notably, new molecules are constantly being discovered and the list is continuously growing. Additionally, substantial progress has been made concerning their differential expression in association with clinical and pathological parameters of tumors and the prognostic and predictive value of their dysregulation in breast cancer carcinogenesis. However, evidence regarding the mechanisms by which adipose tissue is involved in the development of TNBC is lacking. In the present article we comment on current data on the suggested involvement of these mediators in breast cancer development and progression, with particular emphasis on TNBC, to draw attention to the design of novel targeted therapies and biomarkers.

HIF-1α in Osteoarthritis: From Pathogenesis to Therapeutic Implications

Osteoarthritis is a common age-related joint degenerative disease. Pain, swelling, brief morning stiffness, and functional limitations are its main characteristics. There are still no well-established strategies to cure osteoarthritis. Therefore, better clarification of mechanisms associated with the onset and progression of osteoarthritis is critical to provide a theoretical basis for the establishment of novel preventive and therapeutic strategies. Chondrocytes exist in a hypoxic environment, and HIF-1α plays a vital role in regulating hypoxic response. HIF-1α responds to cellular oxygenation decreases in tissue regulating survival and growth arrest of chondrocytes. The activation of HIF-1α could regulate autophagy and apoptosis of chondrocytes, decrease inflammatory cytokine synthesis, and regulate the chondrocyte extracellular matrix environment. Moreover, it could maintain the chondrogenic phenotype that regulates glycolysis and the mitochondrial function of osteoarthritis, resulting in a denser collagen matrix that delays cartilage degradation. Thus, HIF-1α is likely to be a crucial therapeutic target for osteoarthritis via regulating chondrocyte inflammation and metabolism. In this review, we summarize the mechanism of hypoxia in the pathogenic mechanisms of osteoarthritis, and focus on a series of therapeutic treatments targeting HIF-1α for osteoarthritis. Further clarification of the regulatory mechanisms of HIF-1α in osteoarthritis may provide more useful clues to developing novel osteoarthritis treatment strategies.

Kaempferol increases intracellular ATP content in C2C12 myotubes under hypoxic conditions by suppressing the HIF-1α stabilization and/or by enhancing the mitochondrial complex IV activity

Kaempferol (KMP) has numerous important biological functions, and we recently showed that it remarkably increased intracellular adenosine triphosphate (ATP) content in C₂C₁₂ myotubes under hypoxic conditions. Since intracellular ATP is generated by aerobic energy metabolism or anaerobic glycolysis, hypoxia inducible factor-1α (HIF-1α) has been shown to be associated with metabolic remodeling and causes metabolic shift from aerobic energy metabolism to anaerobic glycolysis in response to hypoxic conditions. Here, we investigate the effects of KMP under hypoxic conditions on the stabilization of HIF-1α in C₂C₁₂ myotubes and its underlying molecular mechanisms. Constitutive HIF-1α protein expression was observed in C₂C₁₂ myotubes, and its expression under hypoxic conditions was remarkably suppressed by KMP by reducing its stability; thus, resulting in an increase in ATP content. Furthermore, KMP strikingly increased the ubiquitination of HIF-1α and promoted its degradation via the ubiquitin proteasome system. Inhibition of HIF-1α by KMP resulted in the abrogation of the expression of glycolytic enzymes such as lactate dehydrogenase A and pyruvate dehydrogenase kinase isozyme 1. In addition, the metabolome profiling showed that KMP promoted oxidative energy production, while the mitochondrial complex activity assay indicated that KMP increased the activity of mitochondrial complex IV. Finally, we showed that KMP inhibited HIF-1α expression and increased intracellular ATP content in the soleus muscle of rats. Taken together, these results suggest that KMP increases intracellular ATP content under hypoxic conditions by suppressing the HIF-1α stabilization and/or by enhancing the mitochondrial complex IV activity in muscle.

Apigenin Induces Autophagy and Cell Death by Targeting EZH2 under Hypoxia Conditions in Gastric Cancer Cells

Hypoxia is a major obstacle to gastric cancer (GC) therapy and leads to chemoresistance as GC cells are frequently exposed to the hypoxia environment. Apigenin, a flavonoid found in traditional medicine, fruits, and vegetables and an HDAC inhibitor, is a powerful anti-cancer agent against various cancer cell lines. However, detailed mechanisms involved in the treatment of GC using APG are not fully understood. In this study, we investigated the biological activity of and molecular mechanisms involved in APG-mediated treatment of GC under hypoxia. APG promoted autophagic cell death by increasing ATG5, LC3-II, and phosphorylation of AMPK and ULK1 and down-regulating p-mTOR and p62 in GC. Furthermore, our results show that APG induces autophagic cell death via the activation of the PERK signaling, indicating an endoplasmic reticulum (ER) stress response. The inhibition of ER stress suppressed APG-induced autophagy and conferred prolonged cell survival, indicating autophagic cell death. We further show that APG induces ER stress- and autophagy-related cell death through the inhibition of HIF-1α and Ezh2 under normoxia and hypoxia. Taken together, our findings indicate that APG activates autophagic cell death by inhibiting HIF-1α and Ezh2 under hypoxia conditions in GC cells.

Micronutrient Food Supplements in Patients with Gastro-Intestinal and Hepatic Cancers

Colorectal carcinogenesis is the second most common cause of mortality across all types of malignancies, followed by hepatic and stomach cancers. Chemotherapy and radiotherapy are key approaches to treating cancer patients, but these carry major concerns, such as a high risk of side effects, poor accessibility, and the non-selective nature of chemotherapeutics. A number of natural products have been identified as countering various forms of cancer with fewer side effects. The potential impact of vitamins and minerals on long-term health, cognition, healthy development, bone formation, and aging has been supported by experimental and epidemiological studies. Successful treatment may thus be highly influenced by the nutritional status of patients. An insufficient diet could lead to detrimental effects on immune status and tolerance to treatment, affecting the ability of chemotherapy to destroy cancerous cells. In recent decades, most cancer patients have been taking vitamins and minerals to improve standard therapy and/or to decrease the undesirable side effects of the treatment together with the underlying disease. On the other hand, taking dietary supplements during cancer therapy may affect the effectiveness of chemotherapy. Thus, micronutrients in complementary oncology must be selected appropriately and should be taken at the right time. Here, the potential impact of micronutrients on gastro-intestinal and hepatic cancers is explored and their molecular targets are laid down.

Functional foods from the tropics to relieve chronic normobaric hypoxia

Functional foods with antioxidant and anti-inflammatory properties are regarded as a complementary therapy to improve chronic diseases such as obesity and inflammatory bowel disease (IBD). Obesity is a chronic low-grade inflammatory state leading to organ damage with increased risk of common diseases including cardiovascular and metabolic disease, non-alcoholic fatty liver disease, osteoarthritis and some cancers. IBD is a chronic intestinal inflammation categorised as Crohn's disease and ulcerative colitis depending on the location of inflammation. These inflammatory states are characterised by normobaric hypoxia in adipose and intestinal tissues, respectively. Tropical foods especially from Australia and South America are discussed in this review to show their potential in attenuation of these chronic diseases. The phytochemicals from these foods have antioxidant and anti-inflammatory activities to reduce chronic normobaric hypoxia in the tissues. These health benefits of the tropical foods are relevant not only for health economy but also in providing a global solution by improving the sustainability of their cultivation and assisting the local economies.

Downregulation of Hypoxia-Inducible Factor-1α by RNA Interference Alleviates the Development of Collagen-Induced Arthritis in Rats

Rheumatoid arthritis (RA) is the most common type of autoimmune arthritis. Hypoxia-inducible factor-1α (HIF-1α) as a transcription factor in response to hypoxia suggests that it could be a potential therapeutic target for the treatment of RA. In this study, we assessed whether the HIF pathway blockade attenuates the manifestations of RA in the collagen-induced arthritis (CIA) rat model. We constructed a short hairpin RNA (shRNA) lentiviral expression vector targeting HIF-1α (pLVX-shRNA-HIF-1α) and to achieve HIF-1α RNA interference. Quantitative RT-PCR, immunofluorescence staining, and western blot were used to detect the expressions of HIF-1α, vascular endothelial growth factor (VEGF), phsopho (p)-p65, and p-IКBɑ mRNA and protein, respectively. Micro-computed tomography was used to investigate joint morphology at different time points after CIA induction. Moreover, enzyme-linked immunosorbent assay (ELISA) was used to monitor the expression of inflammatory cytokines. In vitro analyses revealed that pLVX-shRNA-HIF-1α effectively inhibited the expression of HIF-1α and VEGF and led to the activation of p-65 and p-IКBɑ, as well as decreased proinflammatory cytokine expression in cell culture. Inhibition of HIF-1α in rats decreased signs of a systemic inflammatory condition, together with decreased pathological changes of RA. Moreover, downregulation of HIF-1α expression markedly reduced the synovitis and angiogenesis. In conclusion, we have shown that pharmacological inhibition of HIF-1 may improve the clinical manifestations of RA.

Rational Design of Nanoparticles to Overcome Poor Tumor Penetration and Hypoxia-Induced Chemotherapy Resistance: Combination of Optimizing Size and Self-Inducing High Level of Reactive Oxygen Species

One tough question induced by the hypoxia in cancer tissue is resistance to anticancer drugs basing on the reactive oxygen species (ROS) mechanism. Furthermore, the hypoxic regions locate in the center of tumor where tumor cells are easily residual and survival due to the poor drug-delivery efficiency even with nanocarriers. In this paper, these problems were well addressed through the rational combination of the enhanced penetration, self-inducing high level of intracellular ROS, and synchronously pH-sensitive drug release, realized by a simple structural and accessible copolymer, poly(poly(ethylene glycol) methyl ether methacrylate-co-(2-methylpropenoic acid-glycerol-cinnamaldehyde)) (PgEMC). For one thing, PgEMC could self-assemble into stable nanoparticles with PEG shell and optimizing diameters of 60 nm to simultaneously facilitate long blood circulation and deep tumor penetration. Second, cinnamylaldehyde moieties could detach from PgEMC NPs in intracellular acidic environment and trigger high level of ROS to allay the doxorubicin (DOX) resistance induced by hypoxia in solid malignancies. Furthermore, the DOX payload in PgEMC NPs could be synchronously released with the intracellular disassembly of PgEMC NPs due to the detaching of cinnamylaldehyde moieties. In 4T1 cells treated with PgEMC/DOX NPs, remarkable elevation of ROS level and enhanced DOX sensitivity in hypoxia environment were observed in in vitro studies. The results of tumor spheroid penetration indicated that 60 nm sized DOX-loaded PgEMC NPs (PgEMC₆₀/DOX) could distribute into deep site of tumor at a high intensity. In vivo studies using a 4T1 breast tumor model, PgEMC₆₀/DOX NPs, showed significant inhibition over 95.4% of the tumor growth. These results reveal that integrating optimizing size, self-inducing ROS, and pH-sensitive drug release into one small-sized nanoparticle can efficiently overcome the poor tumor penetration and hypoxia-induced chemotherapy resistance.

Long term treatment with quercetin in contrast to the sulfate and glucuronide conjugates affects HIF1α stability and Nrf2 signaling in endothelial cells and leads to changes in glucose metabolism

Endothelial functionality profoundly contributes to cardiovascular health. The effects of flavonoids shown to improve endothelial performance include regulating blood pressure by modulating endothelial nitric oxide synthase and NADPH oxidases, but their impact on glucose uptake and metabolism has not been explored. We treated human umbilical vein endothelial cells (HUVEC) with the flavonoid quercetin and its circulating metabolites acutely and chronically, then assessed glucose uptake, glucose metabolism, gene transcription and protein expression. Acute treatment had no effect on glucose uptake, ruling out any direct interaction with sugar transporters. Long term treatment with quercetin, but not quercetin 3-O-glucuronide or 3'-O-sulfate, significantly increased glucose uptake. Heme oxygenase-1 (HO-1) was induced by quercetin but not its conjugates, but was not implicated in the glucose uptake stimulation since hemin, a classical inducer of HO-1, did not affect glucose metabolism. Quercetin increased stability of the transcription factor hypoxia induced factor 1α (HIF1α), a powerful stimulant of glucose metabolism, which was also paralleled by treatment with a prolyl-4-hydroxylase inhibitor dimethyloxalylglycine (DMOG). 6-Phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), which regulates the rate of glycolysis, was upregulated by both quercetin and DMOG. Pyruvate dehydrogenase kinase (PDK) isoforms regulate pyruvate dehydrogenase; PDK2 and PDK4 were down-regulated by both effectors, but only DMOG also upregulated PDK1 and PDK3. Quercetin, but not DMOG, increased glucose-6-phosphate dehydrogenase. Chronic quercetin treatment also stimulated glucose transport across the HUVEC monolyer in a 3D culture model. Gene expression of several flavonoid transporters was repressed by quercetin, but this was either abolished (Organic anion transporter polypeptide 4C1) or reversed (Multidrug resistance gene 1) by both conjugates. We conclude that quercetin and its circulating metabolites differentially modulate glucose uptake/metabolism in endothelial cells, through effects on HIF1α and transcriptional regulation of energy metabolism.

Anticancer potential of dietary vitamin D and ascorbic acid: A review

Cancers have been the leading cause of death worldwide and poor diet and physical inactivity are major risk factors in cancer-related deaths. Micronutrients such as vitamins and minerals appear to have preventive properties against cancer. One important mechanism by which dietary changes can exert preventive effects on cancer is via the modulation of micronutrient concentrations in target tissues. Many of these micronutrients are available in the form of dietary supplements, and the intake of these supplements is prevalent in various parts of the world. However, in most cases, it is not known which micronutrient (or combination of micronutrients) is best when it comes to lowering the risk of cancer. The present review illustrates the effect of vitamin D and ascorbic acid intake on preventing cancer.

Triple-negative breast cancer and its association with obesity

Triple-negative breast cancer (TNBC) is a subtype of breast cancer that lacks expression of the estrogen and progesterone receptor and does not overexpress human epidermal growth factor 2 receptor protein. TNBC is associated with special characteristics, including aggressiveness, poor prognosis and poor response to treatment, and has been attracting increasing attention worldwide. Obesity is a well-documented factor exerting a significant effect on the development of breast cancer, including TNBC. The purpose of the present review was to focus on the association between obesity and TNBC and provide a summary of novel research findings. The aim was to highlight the association between TNBC and obesity and provide an overview of novel outlooks on clinical issues, biological rationale, novel targeted therapies and prognosis, in order to draw attention to the significance of weight management, primary prevention, early diagnosis and treatment of this intractable disease.

Chlorogenic acid and coffee prevent hypoxia-induced retinal degeneration

This study explored whether chlorogenic acid (CGA) and coffee have protective effects against retinal degeneration. Under hypoxic conditions, the viability of transformed retinal ganglion (RGC-5) cells was significantly reduced by treatment with the nitric oxide (NO) donor S-nitroso-N-acetylpenicillamine (SNAP). However, pretreatment with CGA attenuated cell death in a concentration-dependent manner. In addition, CGA prevented the up-regulation of apoptotic proteins such as Bad and cleaved caspase-3. Similar beneficial effects of both CGA and coffee extracts were observed in mice that had undergone an optic nerve crush (ONC) procedure. CGA and coffee extract reduced cell death by preventing the down-regulation of Thy-1. Our in vitro and in vivo studies demonstrated that coffee and its major component, CGA, significantly reduce apoptosis of retinal cells induced by hypoxia and NO, and that coffee consumption may help in preventing retinal degeneration.

Molecular link between vitamin D and cancer prevention

The metabolite of vitamin D, 1α,25-dihydroxyvitamin D₃ (also known as calcitriol), is a biologically active molecule required to maintain the physiological functions of several target tissues in the human body from conception to adulthood. Its molecular mode of action ranges from immediate nongenomic responses to longer term mechanisms that exert persistent genomic effects. The genomic mechanisms of vitamin D action rely on cross talk between 1α,25-dihydroxyvitamin D₃ signaling pathways and that of other growth factors or hormones that collectively regulate cell proliferation, differentiation and cell survival. In vitro and in vivo studies demonstrate a role for vitamin D (calcitriol) in modulating cellular growth and development. Vitamin D (calcitriol) acts as an antiproliferative agent in many tissues and significantly slows malignant cellular growth. Moreover, epidemiological studies have suggested that ultraviolet-B exposure can help reduce cancer risk and prevalence, indicating a potential role for vitamin D as a feasible agent to prevent cancer incidence and recurrence. With the preventive potential of this biologically active agent, we suggest that countries where cancer is on the rise--yet where sunlight and, hence, vitamin D may be easily acquired--adopt awareness, education and implementation strategies to increase supplementation with vitamin D in all age groups as a preventive measure to reduce cancer risk and prevalence.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Flavonoids induce HIF-1alpha but impair its nuclear accumulation and activity

Hypoxia-inducible factor-1alpha (HIF-1alpha) is the regulatory subunit of the transcription factor HIF-1, which is highly involved in the pathology of diseases associated with tissue hypoxia. In this study we investigated the ability of plant flavonoids to induce HIF-1alpha and regulate HIF-1 transcriptional activity in HeLa cells. We demonstrate for the first time that the flavonoids baicalein, luteolin and fisetin, as well as the previously investigated quercetin, induce HIF-1alpha under normal oxygen pressure, whereas kaempferol, taxifolin, and rutin are inactive. We further reveal that the capability of flavonoids to bind efficiently intracellular iron and their lipophilicity are essential for HIF-1alpha induction. Despite the ability of flavonoids to stabilize HIF-1alpha, the transcriptional activity of HIF-1 induced by flavonoids was significantly lower than that observed with the iron chelator and known HIF-1 inducer, desferrioxamine (DFO). Furthermore, when cells in which HIF-1 had been induced by DFO were also treated with flavonoids, the transcriptional activity of HIF-1 was strongly impaired without simultaneous reduction in HIF-1alpha protein levels. Localization of HIF-1alpha by immuno- and direct fluorescence microscopy and in vitro phosphorylation assays suggest that flavonoids inhibit HIF-1 activity by impairing the MAPK-dependent phosphorylation of HIF-1alpha, thereby decreasing its nuclear accumulation.

Mechanism of leptin expression in breast cancer cells: role of hypoxia-inducible factor-1alpha

We reported previously that the obesity hormone leptin is overexpressed in breast cancer biopsies. Here, we investigated molecular mechanisms involved in this process, focusing on conditions that are associated with obesity, that is, hyperinsulinemia and induction of hypoxia. By using quantitative real-time PCR, immunofluorescent detection of proteins and enzyme-linked immunosorbent assays, we found that treatment of MCF-7 breast cancer cells with high doses of insulin or the hypoxia-mimetic agent CoCl2, or culturing the cells under hypoxic conditions significantly increased the expression of leptin mRNA and protein. Notably, the greatest leptin mRNA and protein expression were observed under combined hyperinsulinemia and hypoxia or hypoxia-mimetic treatments. Luciferase reporter assays suggested that increased leptin synthesis could be related to the activation of the leptin gene promoter. DNA affinity precipitation and chromatin immunoprecipitation experiments revealed that insulin, CoCl2 and/or hypoxia treatments augmented nuclear accumulation of hypoxia-inducible factor-1alpha (HIF-1alpha) and increased its interaction with several upstream leptin regulatory sequences, especially with the proximal promoter containing four hypoxia-response elements and three GC-rich regions. By using reverse chromatin precipitation, we determined that loading of HIF-1alpha on the proximal leptin promoter concurred with the recruitment of p300, the major HIF coactivator, suggesting that the HIF/p300 complex is involved in leptin transcription. The importance of HIF-1alpha in insulin- and CoCl2-activated leptin mRNA and protein expression was confirmed using RNA interference.

Overexpression of human papillomavirus type 16 oncoproteins enhances hypoxia-inducible factor 1 alpha protein accumulation and vascular endothelial growth factor expression in human cervical carcinoma cells

PURPOSE

Human papillomavirus (HPV)-16 oncoproteins, E6 and E7, are associated with enhanced tumor angiogenesis in human cervical cancers. The purpose of this study was (a) to investigate whether expression of HPV-16 E6 and E7 oncoproteins induces hypoxia-inducible factor 1 alpha (HIF-1 alpha) and vascular endothelial growth factor expression in cervical cancer cells; and (b) to assess the effect of resveratrol on 16 E6- and E7-induced HIF-1 alpha and VEGF gene expression.

EXPERIMENTAL DESIGN

Human cervical cancer cell lines C-33A and HeLa were transiently cotransfected with pSG5-HPV-16 E6 or 16 E7 constructs along with HIF-1 alpha small interfering RNA (siRNA) or nonspecific siRNA. The expression of HIF-1 alpha/VEGF was measured using real-time PCR, Western blot analysis, or ELISA. The in vitro angiogenic activity induced by 16 E6- and E7-transfected cells was examined. The effect of resveratrol on oncoprotein-induced HIF-1 alpha/VEGF expression and in vitro angiogenesis was investigated.

RESULTS

HPV-16 E6- and E7-transfected cervical cancer cells express increased HIF-1 alpha protein and VEGF expression. These stimulatory effects were abrogated by cotransfection with either HIF-1 alpha siRNA or treatment with resveratrol. Blocking extracellular signal-regulated kinase 1/2 (ERK 1/2) and phosphoinositide-3-kinase by PD98059 and LY294002, respectively, abolished 16 E6- and E7-induced HIF-1 alpha and VEGF expression. Functionally, we showed that HPV-16 E6- and E7-transfected cervical cancer cells stimulated in vitro capillary or tubule formation, and these angiogenic effects could be abolished either by cotransfection with HIF-1 alpha siRNA or by treatment with resveratrol.

CONCLUSION

HPV-16 oncoproteins contribute to enhanced angiogenesis in cervical cancer cells via HIF-1 alpha-dependent VEGF expression. Resveratrol suppresses 16 E6- and E7-induced HIF-1 alpha-mediated angiogenic activity and, thus, is a promising chemotherapeutic agent for human cervical cancer.

Antioxidant Enzymes during Hypoxia-Anoxia Signaling Events inCrocus sativusL. Corm

The activity of reactive oxygen species (ROS)-scavenging enzymes, catalase, superoxide dismutase (SOD), glutathione peroxidase, o-dianisidine and ascorbate peroxidases, was investigated in Crocus sativus L. corms cultivated in normoxic and hypoxic-anoxic conditions. The activity of the ROS-scavenging enzymes studied varied during cultivation. However, the pattern of ROS-scavenging enzymes production was different in corms cultivated in normoxic and hypoxic-anoxic conditions. In normoxic conditions, only the activities of peroxidases and SOD were stimulated. In dormant corms placed under hypoxia-anoxia, the activities of catalase, SOD, and glutathione peroxidase were stimulated, with the highest stimulation observed for catalase, followed by SOD, and then glutathione peroxidase. In corms that had been rooted for 3 days before being placed in hypoxia-anoxia, the activities of all ROS-scavenging enzymes studied were stimulated with the highest stimulation still observed for catalase, followed by the peroxidases, and finally SOD. Thus catalase was the prevailing enzyme produced under hypoxia-anoxia.

Angiogenesis: from plants to blood vessels

Angiogenesis is a major pathological component of diseases such as cancer and coronary heart disease. Although major advances have been made and encouraging clinical results obtained, safer and more effective approaches are required. The identification of new drugs from plants has a long and successful history, and certain proangiogenic and antiangiogenic plant components have been used in traditional Chinese medicine (TCM) for thousands of years. Similar to Western combination therapy, TCM uses mixtures of plant extracts, termed fufang, to maximize efficacy and minimize adverse effects or toxicity. More evidence-based research and chemical optimization of these compounds could further enhance the effectiveness of these plant-based medicines in angiotherapy.

Increased expression of leptin and the leptin receptor as a marker of breast cancer progression: possible role of obesity-related stimuli

PURPOSE

Recent in vitro studies suggested that the autocrine leptin loop might contribute to breast cancer development by enhancing cell growth and survival. To evaluate whether the leptin system could become a target in breast cancer therapy, we examined the expression of leptin and its receptor (ObR) in primary and metastatic breast cancer and noncancer mammary epithelium. We also studied whether the expression of leptin/ObR in breast cancer can be induced by obesity-related stimuli, such as elevated levels of insulin, insulin-like growth factor-I (IGF-I), estradiol, or hypoxic conditions.

EXPERIMENTAL DESIGN

The expression of leptin and ObR was examined by immunohistochemistry in 148 primary breast cancers and 66 breast cancer metastases as well as in 90 benign mammary lesions. The effects of insulin, IGF-I, estradiol, and hypoxia on leptin and ObR mRNA expression were assessed by reverse transcription-PCR in MCF-7 and MDA-MB-231 breast cancer cell lines.

RESULTS

Leptin and ObR were significantly overexpressed in primary and metastatic breast cancer relative to noncancer tissues. In primary tumors, leptin positively correlated with ObR, and both biomarkers were most abundant in G3 tumors. The expression of leptin mRNA was enhanced by insulin and hypoxia in MCF-7 and MDA-MB-231 cells, whereas IGF-I and estradiol stimulated leptin mRNA only in MCF-7 cells. ObR mRNA was induced by insulin, IGF-I, and estradiol in MCF-7 cells and by insulin and hypoxia in MDA-MB-231 cells.

CONCLUSIONS

Leptin and ObR are overexpressed in breast cancer, possibly due to hypoxia and/or overexposure of cells to insulin, IGF-I, and/or estradiol.

Supercritical CO2 extraction and purification of compounds with antioxidant activity

Supercritical fluid extraction (SCFE), based on the utilization of a fluid under supercritical conditions, is a technology suitable for extraction and purification of a variety of compounds, particularly those that have low volatility and/or are susceptible to thermal degradation. The interest in SCFE is promoted by legal limitations of conventional solvents for food and pharmaceutical uses. The physicochemical properties of supercritical CO2 (higher diffusivity, lower viscosity, and lower surface tension than conventional solvents) facilitate mass transfer and allow an environmentally friendly operation. This article presents a comprehensive compilation of data on the supercritical CO2 extraction of antioxidant compounds from vegetal materials, with particular attention to those of a phenolic nature. Aspects concerning the supercritical operation for extraction and fractionation of antioxidants compounds are considered, including equilibrium solubility of pure compounds and effects of the operational conditions on the antioxidant activity of isolated fractions. The data are compared to those reported for synthetic antioxidants and natural extracts obtained by conventional solvent extraction from vegetal matrices.