Development of novel therapeutic strategies that target HIF-1

Transcriptional regulation and post-translational modifications in the glycolytic pathway for targeted cancer therapy

Cancer cells largely rely on aerobic glycolysis or the Warburg effect to generate essential biomolecules and energy for their rapid growth. The key modulators in glycolysis including glucose transporters and enzymes, e.g. hexokinase 2, enolase 1, pyruvate kinase M2, lactate dehydrogenase A, play indispensable roles in glucose uptake, glucose consumption, ATP generation, lactate production, etc. Transcriptional regulation and post-translational modifications (PTMs) of these critical modulators are important for signal transduction and metabolic reprogramming in the glycolytic pathway, which can provide energy advantages to cancer cell growth. In this review we recapitulate the recent advances in research on glycolytic modulators of cancer cells and analyze the strategies targeting these vital modulators including small-molecule inhibitors and microRNAs (miRNAs) for targeted cancer therapy. We focus on the regulation of the glycolytic pathway at the transcription level (e.g., hypoxia-inducible factor 1, c-MYC, p53, sine oculis homeobox homolog 1, N6-methyladenosine modification) and PTMs (including phosphorylation, methylation, acetylation, ubiquitination, etc.) of the key regulators in these processes. This review will provide a comprehensive understanding of the regulation of the key modulators in the glycolytic pathway and might shed light on the targeted cancer therapy at different molecular levels.

Anti-oxidant potential of plants and probiotic spp. in alleviating oxidative stress induced by H2O2

Cells produce reactive oxygen species (ROS) as a metabolic by-product. ROS molecules trigger oxidative stress as a feedback response that significantly initiates biological processes such as autophagy, apoptosis, and necrosis. Furthermore, extensive research has revealed that hydrogen peroxide (H2O2) is an important ROS entity and plays a crucial role in several physiological processes, including cell differentiation, cell signalling, and apoptosis. However, excessive production of H2O2 has been shown to disrupt biomolecules and cell organelles, leading to an inflammatory response and contributing to the development of health complications such as collagen deposition, aging, liver fibrosis, sepsis, ulcerative colitis, etc. Extracts of different plant species, phytochemicals, and Lactobacillus sp (probiotic) have been reported for their anti-oxidant potential. In this view, the researchers have gained significant interest in exploring the potential plants spp., their phytochemicals, and the potential of Lactobacillus sp. strains that exhibit anti-oxidant properties and health benefits. Thus, the current review focuses on comprehending the information related to the formation of H2O2, the factors influencing it, and their pathophysiology imposed on human health. Moreover, this review also discussed the anti-oxidant potential and role of different extract of plants, Lactobacillus sp. and their fermented products in curbing H2O2‑induced oxidative stress in both in-vitro and in-vivo models via boosting the anti-oxidative activity, inhibiting of important enzyme release and downregulation of cytochrome c, cleaved caspases-3, - 8, and - 9 expression. In particular, this knowledge will assist R&D sections in biopharmaceutical and food industries in developing herbal medicine and probiotics-based or derived food products that can effectively alleviate oxidative stress issues induced by H2O2 generation.

The Role of Imaging Biomarkers to Guide Pharmacological Interventions Targeting Tumor Hypoxia

Hypoxia is a common feature of solid tumors that contributes to angiogenesis, invasiveness, metastasis, altered metabolism and genomic instability. As hypoxia is a major actor in tumor progression and resistance to radiotherapy, chemotherapy and immunotherapy, multiple approaches have emerged to target tumor hypoxia. It includes among others pharmacological interventions designed to alleviate tumor hypoxia at the time of radiation therapy, prodrugs that are selectively activated in hypoxic cells or inhibitors of molecular targets involved in hypoxic cell survival (i.e., hypoxia inducible factors HIFs, PI3K/AKT/mTOR pathway, unfolded protein response). While numerous strategies were successful in pre-clinical models, their translation in the clinical practice has been disappointing so far. This therapeutic failure often results from the absence of appropriate stratification of patients that could benefit from targeted interventions. Companion diagnostics may help at different levels of the research and development, and in matching a patient to a specific intervention targeting hypoxia. In this review, we discuss the relative merits of the existing hypoxia biomarkers, their current status and the challenges for their future validation as companion diagnostics adapted to the nature of the intervention.

Enantiomeric Isopulegol as the Chiral Pool in the Total Synthesis of Bioactive Agents

Isopulegol, a pool of abundant chiral terpene, has long served as the starting material for the total synthesis of isopulegol-based drugs. As an inexpensive and versatile starting material, this compound continues to serve modern synthetic chemistry. This review highlights the total syntheses of terpenoids in the period from 1980 to 2020 in which with isopulegol applied as a building block.

Hypoxia-inducible factor (HIF) inhibitors: a patent survey (2016-2020)

Introduction: Hypoxia-inducible factor (HIF) is a master regulator of oxygen homeostasis. The increased expression of genes targeted by HIF is associated with many human diseases, including ischemic cardiovascular disease, stroke, chronic lung disease, and cancer.Areas covered: This patent survey summarizes the information about patented HIF inhibitors over the last 5 years.Expert opinion: HIF inhibitors have shown promise for the treatment of hypoxic pulmonary hypertension, a circadian rhythm disorder, calcific aortic valve disease, cerebrovascular accident, and heterotopic ossification. In addition, HIF-2α inhibitors can be used for the treatment or prevention of iron overload disorders, Crohn's disease, ulcerative colitis, and thyroid eye disease, or to improve muscle generation and repair. PT2385 completed phase I clinical trials for the treatment of clear cell renal cell carcinoma. It exerted a higher synergistic inhibitory effect on tumor growth in combination with anti-PD-1 antibody, in comparison with each treatment alone, indicating that effective immunotherapy for solid tumors counteracts of the immunosuppression induced by hypoxia. Therefore, considering the effects of hypoxia on cancer cells, stromal cells, and effector immune cells, it is important to develop inhibitors of molecular pathways activated by hypoxia for successful treatments.

Novel evidence for oncogenic piRNA-823 as a promising prognostic biomarker and a potential therapeutic target in colorectal cancer

piRNA‐823 as a member of the piRNA family is reported to promote tumour cell proliferation in multiple myeloma and hepatocellular cancer. However, few studies on the function of piRNA‐823 in colorectal cancer (CRC). Our present study data showed that piRNA‐823 plays an oncogene role in CRC cells. Inhibition of piRNA‐823 can significantly inhibit the proliferation, invasion and apoptosis resistance of CRC cells. Mechanism studies have shown that piRNA‐823 inhibits the ubiquitination of hypoxia‐inducible factor‐1 alpha (HIF‐1α) by up‐regulating the expression of Glucose‐6‐phosphate dehydrogenase (G6PD) and ultimately up‐regulates the glucose consumption of carcinoma cells and inhibits the content of intracellular reactive oxygen species (ROS). Therefore, we speculate piRNA‐823 promotes the proliferation, invasion and apoptosis resistance of CRC cells by regulating G6PD/HIF‐1α pathway. In this study, we set up the cancer‐promoting function recovery experiment of piRNA‐823 by silencing G6PD gene to confirm the dominance of the above‐mentioned pathways. Using clinical samples, we found that overexpression of piRNA‐823 correlated with poor overall survival and predicted a poor response to adjuvant chemotherapy of patients with CRC. In a word, our research has further enriched the theory of piRNA‐823 promoting the progression of CRC, and laid a solid foundation for the development of piRNA‐823‐based gene therapy for CRC and its use as a promising prognostic biomarker in CRC patients.

Synthesis and biological evaluation of novel 5,6,7-trimethoxy flavonoid salicylate derivatives as potential anti-tumor agents

5,6,7-Trimethoxy flavonoid salicylate derivatives were designed by the joining of three important pharmacophores (TMP, flavonoid, and SA) according to the combination principle. A series of novel trimethoxy flavonoid salicylate derivatives were synthesized and their in vitro anti-tumor activities were evaluated. Among these derivatives, compound 7f exhibited excellent antiproliferative activity against HGC-27 cells and MGC-803 cells with IC₅₀ values of 10.26 ± 6.94 μM and 17.17 ± 3.03 μM, respectively. Subsequently, the effects on cell colony formation (clonogenic survival assay), cell migration (wound healing assay), cell cycle distribution (PI staining assay), cell apoptosis (Hoechst 33258 staining assay and annexin V-FITC/PI dual staining assay), lactate level (lactate measurement), microtubules disarrangement (immunofluorescence staining analysis) and docking posture (molecular docking simulation) were determined. Further western blot analysis confirmed that compound 7f could effectively down-regulate the expression of glycolysis-related proteins HIF-1α, PFKM and PKM2 and tumor angiogenesis-related proteins VEGF. Overall, these studies suggested that compound 7f, as the representative compound of those, might be a promising candidate for the treatment of gastric cancer and deserved the further studies.

Baseline [(18)F]FMISO μPET as a Predictive Biomarker for Response to HIF-1α Inhibition Combined with 5-FU Chemotherapy in a Human Colorectal Cancer Xenograft Model

PURPOSE

The purpose of this study was to characterize imaging biomarkers for the potential benefit of hypoxia-inducible factor-1 (HIF-1)α inhibition (by PX-12) during 5-fluorouracil (5-FU) chemotherapy in the treatment of colorectal cancer (CRC).

PROCEDURES

Therapy response to 5-FU ± PX-12 was assessed with baseline [(18)F]fluoromisonidazole ([(18)F]FMISO) and longitudinal 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) positron emission computed tomography (μPET/CT) in CRC xenograft model (n = 36) during breathing of a hypoxic (10 % O2) or normoxic (21 % O2) atmosphere. Ex vivo, immunohistochemistry was performed.

RESULTS

Baseline [(18)F]FMISO uptake and relative tumor volume (RTV) 2 days after 5-FU or 5-FU + PX-12 administration correlated significantly (p ≤ 0.01). Under hypoxic breathing conditions, [(18)F]FDG uptake (-53.1 ± 8.4 %) and Ki67 expression (-16 %) decreased and RTV stagnated in the 5-FU + PX-12 treatment group, but not in 5-FU alone-treated tumors. Under normoxic breathing, [(18)F]FDG uptake (-23.5 ± 15.2 % and -72.8 ± 7.1 %) and Ki67 expression (-5 % and -19 %) decreased and RTV stagnated in both the 5-FU and the combination treatment group, respectively.

CONCLUSION

Baseline [(18)F]FMISO μPET may predict the beneficial effect of HIF-1α inhibition during 5-FU chemotherapy in CRC.

Expression of hypoxia inducible factor 1 alpha and its clinical significance in esophageal carcinoma: A meta-analysis

Many studies have analyzed the relationship between hypoxia inducible factor 1 alpha expression and its relation to differentiation, lymph node metastasis, and other clinicopathological variables of esophageal carcinoma, but the results are still inconsistent. This meta-analysis was carried out to explore hypoxia inducible factor 1 alpha in esophageal carcinoma and its correlation with clinicopathological features and prognosis, in order to provide comprehensive reference for clinic. A total of 18 studies including 1566 patients with esophageal squamous cell carcinoma were enrolled. The results showed that compared with para-carcinoma tissue, the expression of hypoxia inducible factor 1 alpha was significantly enhanced (odds ratio = 0.122, 95% confidence interval = 0.074-0.201, p = 0.000); hypoxia inducible factor 1 alpha was associated with differentiation (odds ratio = 1.458, 95% confidence interval = 1.108-1.920, p = 0.007), T classification (odds ratio = 0.457, 95% confidence interval = 0.265-0.786, p = 0.005), lymph node metastasis (odds ratio = 0.337, 95% confidence interval = 0.185-0.614, p = 0.000), and pathological tumor-node-metastasis stage (odds ratio = 0.362, 95% confidence interval = 0.177-0.740, p = 0.005), whereas there was no relation to histological grade, lymphatic vessel invasion, blood vessel invasion, 3- to 5-year overall survival and disease-free survival. Patients with hypoxia inducible factor 1 alpha overexpression had poor differentiation, increased depth of tumor invasion, more lymph node metastasis, and late pathological tumor-node-metastasis stage. Hypoxia inducible factor 1 alpha could be an indicator for differentiation, T classification, lymph node metastasis, and pathological tumor-node-metastasis stage, and it is worth further study.

Knockdown of Hypoxia-Inducible Factor 1α Improved the Efficacy of Low-Dose Metronomic Chemotherapy of Paclitaxel in Human Colon Cancer Xenografts

Low-dose metronomic chemotherapy represents a new strategy for solid tumor treatments with a strong antiangiogenic activity and few side effects. However, low-dose metronomic therapy alone is not always as effective as traditional chemotherapy on eradication of tumor. On the contrary, low-dose metronomic in some cases could stimulate tumor growth due to hypoxia of tumor cells induced during therapy. Our study aimed to investigate whether knockdown of hypoxia-inducible factor-1α expression in tumor cell could facilitate low-dose metronomic therapy with paclitaxel for human colon cancer. Human colon cancer cell line (HT-29) stably transfected with specific short hairpin RNAs silencing hypoxia-inducible factor-1α exhibited marked attenuation of hypoxia-induced expression of the target genes such as vascular endothelial growth factor, glucose transporter 1, and P-glycoprotein. Compared with HT-29-c xenograft tumor model established by subcutaneous injection of HT-29 cells stably transfected with scrambled control short hairpin RNA, HT-29-ih xenograft tumor model showed more significant and long-lasting antitumor responses of empirical metronomic paclitaxel regimens, accompanied by drastic angiogenesis decrease and neglectable toxicity. All these data indicated that the combination of paclitaxel low-dose metronomic therapy with hypoxia-inducible factor-1α knockdown might provide a potent battle against colon cancer.

Hypoxia-Inducible Factor-1: A Critical Player in the Survival Strategy of Stressed Cells

HIF-1 activation has been well known as an adaptive strategy to hypoxia. Recently it became clear that hypoxia was often accompanied by insufficient supply of glucose or amino acids as a common result of poor circulation that frequently occurs in solid tumors and ischemic lesions, creating a mixed nutrient insufficiency. In response to nutrient insufficiency, stressed cells elicit survival strategies including activation of AMPK and HIF-1 to cope with the stress. Particularly, in solid tumors, HIF-1 promotes cell survival and migration, stimulates angiogenesis, and induces resistance to radiation and chemotherapy. Interestingly, radiation and some chemotherapeutics are reported to trigger the activation of AMPK. Here we discuss the recent advances that may potentially link the stress responsive mechanisms including AMPK activation, ATF4 activation and the enhancement of Hsp70/Hsp90 function to HIF-1 activation. Potential implication and application of the stress-facilitated HIF-1 activation in solid tumors and ischemic disorders will be discussed. A better understanding of HIF-1 activation in cells exposed to stresses is expected to facilitate the design of therapeutic approaches that specifically modulate cell survival strategy.

Phospholipase D1 protein coordinates dynamic assembly of HIF-1α-PHD-VHL to regulate HIF-1α stability

Hypoxia-inducible factor-1α (HIF-1α) is a master transcriptional regulator of cellular response to hypoxia. In normoxia, HIF-1α is degraded through the prolyl hydroxylase (PHD) and von Hippel-Lindau (VHL) ubiquitination pathway. However, it is unknown whether PHD and VHL exert their enzymatic activities on HIF-1α separately or as a multiprotein complex. Here, we show that phospholipase D1 (PLD1) protein itself acts as a molecular platform, interacting directly with HIF-1α, PHD, and VHL, thereby dynamically assembling a multiprotein complex that mediates efficient degradation of HIF-1α in an O₂-dependent manner. PLD1 depletion prevents degradation of HIF-1α; however, overall, PLD1 activity is predominantly involved in the upregulation of HIF-1α through increased translation, despite negative regulation of HIF-1α stability by PLD1 protein itself, suggesting dual roles of PLD1 in the regulation of HIF-1α. Disruption of the interactions of PLD1 with the proteins might be involved in hypoxic stabilization of HIF-1α. Interestingly, the pleckstrin homology domain interacting with these proteins promoted degradation of HIF-1α independent of oxygen concentration and suppressed tumor progression. These observations define a novel function of PLD1 as a previously unrecognized HIF-1α regulator.

Regulation of lung development and regeneration by the vascular system

Blood vessels have been described a long time ago as passive circuits providing sufficient blood supply to ensure proper distribution of oxygen and nutrition. Blood vessels are mainly formed during embryonic development and in the early postnatal period. In the adult, blood vessels are quiescent, but can be activated and subsequently induced under pathophysiological conditions, such as ischemia and tumor growth. Surprisingly, recent data have suggested an active function for blood vessels, named angiocrine signaling, releasing trophogens which regulate organ development and organ regeneration including in the pancreas, lung, tumor cells, liver and bone. Lung development is driven by hypoxia as well as an intense endothelial-epithelial interaction, and important mechanisms contributing to these processes have recently been identified. This review aims to summarize recent developments and concepts about embryonic pulmonary vascular development and lung regeneration. We discuss hypoxia-inducible factor HIF-2α and vascular endothelial growth factor VEGF as important mediators in lung development and focus on endothelial-epithelial interactions and angiocrine signaling mechanisms.

Activation of HIF-1α and LL-37 by commensal bacteria inhibits Candida albicans colonization

Candida albicans colonization is required for invasive disease^1-3. Unlike humans, adult mice with mature intact gut microbiota are resistant to C. albicans gastrointestinal (GI) colonization^2,4. But the factors that promote C. albicans colonization resistance are unknown. Here we demonstrate that commensal anaerobic bacteria – specifically Clostridial Firmicutes (Clusters IV and XIVa) and Bacteroidetes – are critical for maintaining C. albicans colonization resistance in mice. Using Bacteroides thetaiotamicron as a model organism, we find that HIF-1α, a transcription factor important for activating innate immune effectors, and the antimicrobial peptide LL37-CRAMP are key determinants of C. albicans colonization resistance. While antibiotic treatment enables C. albicans colonization, pharmacologic activation of colonic Hif1a induces CRAMP expression and results in a significant reduction of C. albicans GI colonization and a 50% decrease in mortality from invasive disease. In the setting of antibiotics, Hif1a and Cramp are required for B. thetaiotamicron-induced protection against CA colonization of the gut. Thus, C. albicans GI colonization modulation by activation of gut mucosal immune effectors may represent a novel therapeutic approach for preventing invasive fungal disease in humans.

Distribution of Hypoxia-Inducible Factor-1α and Glucose Transporter-1 in Human Tongue Cancers

PURPOSE

Oral squamous cell carcinomas have the potential for rapid and unlimited growth. Therefore, hypoxic tissue areas are common in these malignant tumors and contribute to cancer progression, therapy resistance, and poor outcomes. The aim of the present study was to analyze the gene product distribution of hypoxia-inducible factor-1α (HIF-1α) and glucose transporter-1 (GLUT-1) in cases of tongue squamous cell carcinoma (TSCC) and to identify a preliminary correlation between these proteins and clinical staging and Brynes's histologic grading system (HGS).

MATERIALS AND METHODS

The sample included 57 cases of TSCC. Histologic sections of 3 μm were submitted to the immunoperoxidase method and semiquantitative analysis. The association between HIF-1α and GLUT-1 expression in TSCC and the clinical stage and the HGS of Bryne (1998) was evaluated using the χ(2) test, with the significance level set at 0.05 (α = 0.05).

RESULTS

HIF-1α was mainly expressed in the nucleus/cytoplasm of neoplastic cells, most specimens exhibited diffuse staining in neoplastic cells (84.2%), and focal staining was only observed in perinecrotic areas (15.8%). GLUT-1 was expressed in the cytoplasm and membrane of malignant cells, and diffuse staining was observed in all cases. The intensity of HIF-1α expression correlated significantly with clinical stage (P = .011) and HGS (P = .002). A significant association was observed between the distribution of HIF-1α expression and metastasis (P = .040). Immunoexpression of GLUT-1 correlated significantly with clinical stage (P = .002) and HGS (P = .000). GLUT-1 expression in the peripheral island was predominant in most low-grade tumors (78.6%); in the high-grade cases, the expression prevailed in the location center/periphery (55.8%). Comparison of the location of the tumor island in the different histologic grades showed a statistically significant difference (P = .025).

CONCLUSION

The expression of HIF and GLUT proteins within TSCC appears to be associated with disease stage, grade, and the presence of metastases. Additional studies are needed to evaluate the diagnostic and prognostic uses of these proteins in the treatment of TSCC.

IGF1 regulates PKM2 function through Akt phosphorylation

Pyruvate kinase M2 (PKM2) acts at the crossroad of growth and metabolism pathways in cells. PKM2 regulation by growth factors can redirect glycolytic intermediates into key biosynthetic pathway. Here we show that IGF1 can regulate glycolysis rate, stimulate PKM2 Ser/Thr phosphorylation and decrease cellular pyruvate kinase activity. Upon IGF1 treatment we found an increase of the dimeric form of PKM2 and the enrichment of PKM2 in the nucleus. This effect was associated to a reduction of pyruvate kinase enzymatic activity and was reversed using metformin, which decreases Akt phosphorylation. IGF1 induced an increased nuclear localization of PKM2 and STAT3, which correlated with an increased HIF1α, HK2, and GLUT1 expression and glucose entrapment. Metformin inhibited HK2, GLUT1, HIF-1α expression and glucose consumption. These findings suggest a role of IGFIR/Akt axis in regulating glycolysis by Ser/Thr PKM2 phosphorylation in cancer cells.

Regenerative therapy and tissue engineering for the treatment of end-stage cardiac failure: new developments and challenges

Regeneration of myocardium through regenerative therapy and tissue engineering is appearing as a prospective treatment modality for patients with end-stage heart failure. Focusing on this area, this review highlights the new developments and challenges in the regeneration of myocardial tissue. The role of various cell sources, calcium ion and cytokine on the functional performance of regenerative therapy is discussed. The evolution of tissue engineering and the role of tissue matrix/scaffold, cell adhesion and vascularisation on tissue engineering of cardiac tissue implant are also discussed.

Inhibition of hypoxia-inducible factors limits tumor progression in a mouse model of colorectal cancer

Hypoxia-inducible factors (HIFs) accumulate in both neoplastic and inflammatory cells within the tumor microenvironment and impact the progression of a variety of diseases, including colorectal cancer. Pharmacological HIF inhibition represents a novel therapeutic strategy for cancer treatment. We show here that acriflavine (ACF), a naturally occurring compound known to repress HIF transcriptional activity, halts the progression of an autochthonous model of established colitis-associated colon cancer (CAC) in immunocompetent mice. ACF treatment resulted in decreased tumor number, size and advancement (based on histopathological scoring) of CAC. Moreover, ACF treatment corresponded with decreased macrophage infiltration and vascularity in colorectal tumors. Importantly, ACF treatment inhibited the hypoxic induction of M-CSFR, as well as the expression of the angiogenic factor (vascular endothelial growth factor), a canonical HIF target, with little to no impact on the Nuclear factor-kappa B pathway in bone marrow-derived macrophages. These effects probably explain the observed in vivo phenotypes. Finally, an allograft tumor model further confirmed that ACF treatment inhibits tumor growth through HIF-dependent mechanisms. These results suggest pharmacological HIF inhibition in multiple cell types, including epithelial and innate immune cells, significantly limits tumor growth and progression.

Directed hydrogenation of acyclic homoallylic alcohols: enantioselective syntheses of (+)- and (-)-laurenditerpenol

Laurenditerpenol is the first marine natural product shown to inhibit hypoxia-inducible factor 1 (HIF-1) activation. Preclinical studies support that the inhibition of HIF-1 is one of the molecular targets for antitumor drug discovery. The synthetically challenging molecular architecture of laurenditerpenol, its absolute stereostructure, and the biological activity of several diastereoisomers were accomplished by our group in 2007 by diastereoselective synthesis. Herein, we report enantioselective syntheses of both enantiomers of laurenditerpenol involving sequential Michael addition and remote homoallylic hydroxyl group-directed asymmetric hydrogenation at ambient temperature and pressure as key reaction steps. The current approach is elegant and overall more efficient than the ones previously reported in the literature.

Study of the etiopathogenesis and differential diagnosis of oral vascular lesions by immunoexpression of GLUT-1 and HIF-1α

BACKGROUND

To investigate whether the immunohistochemical expression of GLUT-1 and HIF-1α is related to the diagnosis and pathogenesis of oral vascular lesions.

STUDY METHODS

Thirty cases each of pyogenic granuloma (PG) and hemangioma were studied. Antibodies against GLUT-1 and HIF-1α were detected by immunoperoxidase staining in 3-μm histological sections, and the results were analyzed qualitatively and quantitatively, respectively. Positive and negative cells were counted, and the mean number of positive cells was calculated for each case.

RESULTS

The initial diagnosis of hemangioma was maintained in only 7 (23%) of the 30 cases studied, which were positive for GLUT-1. The remaining 23 cases were reclassified as vascular malformation (VM) (n = 13) and PG (n = 10) due to the absence of staining. The endothelium of blood vessels was negative for GLUT-1 in all cases initially diagnosed as PG (n = 30). The percentage of HIF-1α-positive cells was higher in cases of PG, followed by hemangiomas and VMs (P = 0.005).

CONCLUSIONS

Histological features are not sufficient to establish the correct diagnosis of oral hemangiomas, and an accurate anamnesis is essential in these cases. In addition, these findings demonstrate that vascular lesions express mediators of angiogenesis, HIF-1α, and suggest that his process may play a role in the pathogenesis of vascular.

Licochalcone E present in licorice suppresses lung metastasis in the 4T1 mammary orthotopic cancer model

We investigated whether licochalcone E (LicE), a phenolic constituent of licorice, inhibits mammary tumor growth and metastasis using animal and cell culture models. 4T1 mammary carcinoma cells were injected into the mammary fat pads of syngeneic BALB/c mice. Starting 7 days after the injection, the mice received LicE (7 or 14 mg/kg body weight/day) via oral gavage for 25 days. LicE suppressed solid tumor growth and lung metastasis, but did not exhibit kidney or liver toxicity. In tumor tissues, LicE treatment induced a reduction in the expression of Ki67, cyclins, and cyclin-dependent kinases and stimulated apoptosis with increased expression of Bax and cleaved caspase-3 but decreased expression of Bcl-2. In addition, LicE decreased expression of CD31, vascular endothelial growth factor (VEGF)-A and C, VEGF-receptor 2, lymphatic vessel endothelial receptor-1, CD45, cyclooxygenase-2, inducible nitric oxide synthase, and hypoxia inducible factor-1α in tumor tissues. In lung tissues, LicE reduced the levels of proinflammatory cytokines and angiogenesis/metastasis-related proteins. In mammary cancer cell cultures, LicE (5-20 μmol/L) dose dependently inhibited cell migration and invasion. LicE inhibited secretion of matrix metalloproteinase-9, urokinase-type plasminogen activator and VEGF-A, and stimulated secretion of tissue inhibitor of metalloproteinase-2 in MDA-MB-231 cells. In addition, LicE inhibited tube formation of vascular endothelial cells. We show that LicE administration suppressed tumor growth and lung metastasis in the mouse model in conjunction with LicE inhibition of cell migration, invasion, and tube formation in vitro. Reduced tumor growth and metastasis in LicE-treated mice may be, at least in part, attributed to reduced inflammation and tumor angiogenesis.

Arginase II expressed in cancer-associated fibroblasts indicates tissue hypoxia and predicts poor outcome in patients with pancreatic cancer

An adequate level of arginine in the tissue microenvironment is essential for T cell activity and survival. Arginine levels are regulated by the arginine-catabolizing enzyme, arginase (ARG). It has been reported that arginase II (ARG2), one of two ARGs, is aberrantly expressed in prostate cancer cells, which convert arginine into ornithine, resulting in a lack of arginine that weakens tumor-infiltrating lymphocytes and renders them dysfunctional. However, immune suppression mediated by ARG2-expressing cancer cells in lung cancer has not been observed. Here we studied the expression of ARG2 in pancreatic ductal carcinoma (PDC) tissue clinicopathologically by examining over 200 cases of PDC. In contrast to prostate cancer, ARG2 expression was rarely demonstrated in PDC cells by immunohistochemistry, and instead ARG2 was characteristically expressed in α-smooth muscle actin-positive cancer-associated fibroblasts (CAFs), especially those located within and around necrotic areas in PDC. The presence of ARG2-expressing CAFs was closely correlated with shorter overall survival (OS; P  = 0.003) and disease-free survival (DFS; P  = 0.0006). Multivariate Cox regression analysis showed that the presence of ARG2-expressing CAFs in PDC tissue was an independent predictor of poorer OS (hazard ratio [HR]  = 1.582, P  = 0.007) and DFS (HR  = 1.715, P  = 0.001) in PDC patients. In addition to the characteristic distribution of ARG2-expressing CAFs, such CAFs co-expressed carbonic anhydrase IX, SLC2A1, or HIF-1α, markers of hypoxia, in PDC tissue. Furthermore, in vitro experiments revealed that cultured fibroblasts extracted from PDC tissue expressed the ARG2 transcript after exposure to hypoxia, which had arginase activity. These results indicate that cancer cell-mediated immune suppression through ARG2 expression is not a general event and that the presence of ARG2-expressing CAFs is an indicator of poor prognosis, as well as hypoxia, in PDC tissue.

Breast cancer chemoprevention: old and new approaches

In 1976, Sporn has defined chemoprevention as “the use of pharmacologic or natural agents that inhibit the development of invasive breast cancer either by blocking the DNA damage that initiates carcinogenesis, or by arresting or reversing the progression of premalignant cells in which such damage has already occurred.” Although the precise mechanism or mechanisms that promote a breast cancer are not completely established, the success of several recent clinical trials in preventive settings in selected high-risk populations suggests that chemoprevention is a rational and an appealing strategy. Breast cancer chemoprevention has focused heavily on endocrine intervention using selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs). Achieving much success in this particular setting and new approaches as low-dose administration are actually under investigations in several topics. Unfortunately, these drugs are active in prevention of endocrine responsive lesions only and have no effect in reducing the risk of estrogen-negative breast cancer. Thus, recently new pathways, biomarkers, and agents likely are to be effective in this subgroup of cancers and were put under investigation. Moreover, the identification of new potential molecular targets and the development of agents aimed at these targets within cancer have already had a significant impact on advanced cancer therapy and provide a wealth of opportunities for chemoprevention. This paper will highlight current clinical research in both ER-positive and ER-negative breast cancer chemoprevention, explaining the biologic effect of the various agents on carcinogenesis and precancerous lesions, and finally presenting an excursus on the state-of-the-art about new molecular targets under investigations in breast cancer settings.

Maslinic acid inhibits the metastatic capacity of DU145 human prostate cancer cells: possible mediation via hypoxia-inducible factor-1α signalling

Maslinic acid is found in various natural sources, most notably in pomace olive oil, and exerts pro-apoptotic activities in various cancer cells in vitro. In the present study, DU145 human prostate cancer cells were cultured with 0-25 μm-maslinic acid to examine the effects of maslinic acid on the metastatic capacity of prostate cancer cells. Maslinic acid significantly (P <0.05) inhibited the basal and epidermal growth factor (EGF)-induced migration (27-64 %), invasion (23-60 %) and adhesion (8-40 %) of DU145 cells. Maslinic acid significantly (P <0·05) down-regulated both basal and EGF-stimulated secretion of matrix metalloproteinase (MMP)-9 (25-67 %), MMP-2 (50-86 %), urokinase-type plasminogen activator (uPA, about 100 %), vascular endothelial growth factor (VEGF, 98-100 %) and tissue inhibitors of metalloproteinases (TIMP)-1, as well as expression of uPA receptor (uPAR), intercellular adhesion molecules (22-33 %), vascular cell adhesion molecules (23-46 %) and E-cadherin, whereas it increased TIMP-2 secretion. Maslinic acid dramatically reduced the levels of hypoxia-inducible factor-1α (HIF-1α) protein and mRNA; the reduction was accompanied by reduced stability, nuclear levels and transcriptional activity of HIF-1α. The levels of phospho-Akt and phospho-extracellular signal-related kinase (ERK) were reduced in cells treated with maslinic acid, and the phosphoinositide 3-kinase inhibitor LY294002 and the mitogen-activated protein kinase kinase inhibitor PD98059 reduced HIF-1α levels and VEGF secretion. The results show that maslinic acid markedly inhibited the migration, invasion and adhesion of DU145 prostate cancer cells. Suppressing HIF-1α activation by inhibiting Akt and ERK activation may be part of the mechanism by which maslinic acid inhibited uPAR, E-cadherin, VEGF and MMP expression in DU145 cells.

Short-term anti-vascular endothelial growth factor treatment elicits vasculogenic mimicry formation of tumors to accelerate metastasis

Background

Antiangiogenic therapy is one of the most significant advances in anticancer treatment. The benefits of antiangiogenic therapies of late-stage cancers have been investigated but are still too limited.

Methods

We used an ovarian cancer model to test the effect of short-term bevacizumab treatment on metastasis as measured by bioluminescence. Western blotting and CD34-PAS dual staining were performed to assess hypoxia-inducible transcription factor-1α (HIF-1α) expression and vasculogenic mimicry(VM) formation. Cell viability was examined by a CCK8 assay.

Results

Bevacizumab demonstrated antitumor effects in models of ovarian cancer, but also accelerated metastasis together, with marked hypoxia and VM formation in mice receiving short-term therapy. Bevacizumab treatment did not affect SKOV3 cell viability and the amount of VM in three-dimensional culture.

Conclusion

These results suggest that antiangiogenic therapy may potentially influence the progression of metastatic disease, which has been linked to the hypoxic response and VM formation.

Comparative analysis of novel and conventional Hsp90 inhibitors on HIF activity and angiogenic potential in clear cell renal cell carcinoma: implications for clinical evaluation

BACKGROUND

Perturbing Hsp90 chaperone function targets hypoxia inducible factor (HIF) function in a von Hippel-Lindau (VHL) independent manner, and represents an approach to combat the contribution of HIF to cell renal carcinoma (CCRCC) progression. However, clinical trials with the prototypic Hsp90 inhibitor 17-AAG have been unsuccessful in halting the progression of advanced CCRCC.

METHODS

Here we evaluated a novel next generation small molecule Hsp90 inhibitor, EC154, against HIF isoforms and HIF-driven molecular and functional endpoints. The effects of EC154 were compared to those of the prototypic Hsp90 inhibitor 17-AAG and the histone deacetylase (HDAC) inhibitor LBH589.

RESULTS

The findings indicate that EC154 is a potent inhibitor of HIF, effective at doses 10-fold lower than 17-AAG. While EC154, 17-AAG and the histone deacetylase (HDAC) inhibitor LBH589 impaired HIF transcriptional activity, CCRCC cell motility, and angiogenesis; these effects did not correlate with their ability to diminish HIF protein expression. Further, our results illustrate the complexity of HIF targeting, in that although these agents suppressed HIF transcripts with differential dynamics, these effects were not predictive of drug efficacy in other relevant assays.

CONCLUSIONS

We provide evidence for EC154 targeting of HIF in CCRCC and for LBH589 acting as a suppressor of both HIF-1 and HIF-2 activity. We also demonstrate that 17-AAG and EC154, but not LBH589, can restore endothelial barrier function, highlighting a potentially new clinical application for Hsp90 inhibitors. Finally, given the discordance between HIF activity and protein expression, we conclude that HIF expression is not a reliable surrogate for HIF activity. Taken together, our findings emphasize the need to incorporate an integrated approach in evaluating Hsp90 inhibitors within the context of HIF suppression.

Hypoxia differentially affects IL-1β-stimulated MMP-1 and MMP-13 expression of fibroblast-like synoviocytes in an HIF-1α-dependent manner

OBJECTIVES

To further understand the expression regulation of MMP-1 and MMP-13 under physiological and pathological conditions, we investigated the combined effects of hypoxia and pro-inflammatory stimuli on the expression of MMP-1 and MMP-13 in rheumatoid synovial fibroblasts.

METHODS

Synovial fibroblasts were cultured under either hypoxic or normoxic conditions in the presence of IL-1β stimulation. The culture supernatant was analysed for secreted levels of VEGF, MMP-1 and MMP-13. Their gene expression was quantified with real-time and semi-quantitative PCR. Another group of cells was transfected with small-interfering RNA (siRNA) specific for hypoxia-inducible factor-1 α (HIF-1α). The protein levels of HIF-1α were detected by western blot analysis.

RESULTS

In response to 10 ng/ml of IL-1β under normoxia, the levels of MMP-1 and MMP-13 increased compared with the levels observed under hypoxia. IL-1β stimulation under hypoxia induced a 2-fold increase in the level of MMP-1 and a 2-fold decrease in the level of MMP-13 compared with cells cultured under normoxia. A similar pattern of differential expression for MMP-1 and MMP-13 was observed with 1 and 5 ng/ml IL-1β, but not at 0.1 ng/ml. The differential expression of MMPs under the combined effect of IL-1β and hypoxia was significantly attenuated by silencing HIF-1α with siRNA.

CONCLUSIONS

Hypoxia in arthritic joints may differentially affect the IL-1β-stimulated expression of MMP-1 and MMP-13 in rheumatoid synovial fibroblasts. This effect is dependent on HIF-1α expression. This hypoxia-mediated differential effect should be taken into consideration when testing the efficiency of therapies that target HIF-1α.

Hepcidin in human iron disorders: diagnostic implications

BACKGROUND

The peptide hormone hepcidin plays a central role in regulating dietary iron absorption and body iron distribution. Many human diseases are associated with alterations in hepcidin concentrations. The measurement of hepcidin in biological fluids is therefore a promising tool in the diagnosis and management of medical conditions in which iron metabolism is affected.

CONTENT

We describe hepcidin structure, kinetics, function, and regulation. We moreover explore the therapeutic potential for modulating hepcidin expression and the diagnostic potential for hepcidin measurements in clinical practice.

SUMMARY

Cell-culture, animal, and human studies have shown that hepcidin is predominantly synthesized by hepatocytes, where its expression is regulated by body iron status, erythropoietic activity, oxygen tension, and inflammatory cytokines. Hepcidin lowers serum iron concentrations by counteracting the function of ferroportin, a major cellular iron exporter present in the membrane of macrophages, hepatocytes, and the basolateral site of enterocytes. Hepcidin is detected in biologic fluids as a 25 amino acid isoform, hepcidin-25, and 2 smaller forms, i.e., hepcidin-22 and -20; however, only hepcidin-25 has been shown to participate in the regulation of iron metabolism. Reliable assays to measure hepcidin in blood and urine by use of immunochemical and mass spectrometry methods have been developed. Results of proof-of-principle studies have highlighted hepcidin as a promising diagnostic tool and therapeutic target for iron disorders. However, before hepcidin measurements can be used in routine clinical practice, efforts will be required to assess the relevance of hepcidin isoform measurements, to harmonize the different assays, to define clinical decision limits, and to increase assay availability for clinical laboratories.

A high-fat diet increases angiogenesis, solid tumor growth, and lung metastasis of CT26 colon cancer cells in obesity-resistant BALB/c mice

We evaluated whether high-fat diet (HFD), in the absence of increased calorie intake, increases colon cancer growth and metastasis. Four-week-old male BALB/c mice were fed on an HFD (60 kcal% fat) or control diet (10 kcal% fat) for 16 wk, after which CT26 colon cancer cells were subcutaneously injected into the right flank. Solid tumor growth and the number and volume of tumor nodules in the lung were increased markedly in the HFD group with only a slight increase in body weight (5.9%). HFD feeding increased tumor tissue levels of Ki67, cyclin A, cyclin D1, CDK2, Bcl-xL, and Bcl-2; reduced p53 levels and TUNEL-positive apoptotic cells; increased the levels of CD45, CD68, CD31, VEGF, P-VEGF receptor-2, iNOS, and COX-2 as well as hemoglobin content; and increased the levels of HIF-1α, P-STAT3-Y705, P-STAT3-S727, P-IκB-α, P-p65, p65, P-c-Jun, P-Akt, P-ERK1/2, P-p38, and P-SAPK/JNK. HFD feeding increased the serum levels of EGF, insulin, IGF-I, IFN-γ, leptin, RANTES, MCP-1, IL-1ra, and SDF-1α and media conditioned by epididymal fat tissue explants from HFD-fed mice caused an increase in microvessel outgrowth from the mouse aorta and tube formation of human umbilical vein endothelial cells. These results indicate that the chronic consumption of an HFD increases colon cancer cell proliferation, tumor angiogenesis, and lung metastasis in mice in the absence of discernible weight gain. HFD feeding increases the levels of growth factors which activate transcription factors, thereby inducing the expression of many genes involved in the stimulation of inflammation, angiogenesis, and cellular proliferation.

Six degrees of separation: the oxygen effect in the development of radiosensitizers

The popular theory six degrees of separation is used in this review as an analogy to relate all radiosensitization to oxygen. As the prime mover of all radiosensitizers, the pervasive influence of oxygen has consciously or unconsciously influenced the direction of research and development and provided the benchmark against which all other compounds and approaches are measured. It is the aim of this review to develop the six degrees of separation from oxygen analogy as a unifying framework for conceptually organizing the field and for giving context to its varied subspecializations and theories. Under such a framework, it would become possible for one area to consider questions and problems found in other areas of radiosensitization, using a common analogy, that would allow for further development and unification of this multifaceted discipline. In this review, approaches to the development of radiosensitizers and the current state of research in this field are discussed, including promising new agents in various stages of clinical development.

Histone deacetylase inhibitors: the epigenetic therapeutics that repress hypoxia-inducible factors

Histone deacetylase inhibitors (HDACIs) have been actively explored as a new generation of chemotherapeutics for cancers, generally known as epigenetic therapeutics. Recent findings indicate that several types of HDACIs repress angiogenesis, a process essential for tumor metabolism and progression. Accumulating evidence supports that this repression is mediated by disrupting the function of hypoxia-inducible factors (HIF-1, HIF-2, and collectively, HIF), which are the master regulators of angiogenesis and cellular adaptation to hypoxia. Since HIF also regulate glucose metabolism, cell survival, microenvironment remodeling, and other alterations commonly required for tumor progression, they are considered as novel targets for cancer chemotherapy. Though the precise biochemical mechanism underlying the HDACI-triggered repression of HIF function remains unclear, potential cellular factors that may link the inhibition of deacetylase activity to the repression of HIF function have been proposed. Here we review published data that inhibitors of type I/II HDACs repress HIF function by either reducing functional HIF-1α levels, or repressing HIF-α transactivation activity. In addition, underlying mechanisms and potential proteins involved in the repression will be discussed. A thorough understanding of HDACI-induced repression of HIF function may facilitate the development of future therapies to either repress or promote angiogenesis for cancer or chronic ischemic disorders, respectively.

Tumour necrosis is a postoperative prognostic marker for pancreatic cancer patients with a high interobserver reproducibility in histological evaluation

Background:

Tumour necrosis reflects the presence of hypoxia, which can be indicative of an aggressive tumour phenotype. The aim of this study was to investigate whether histological necrosis is a useful predictor of outcome in patients with pancreatic ductal carcinoma (PDC).

Methods:

We reviewed histopathological findings in 348 cases of PDC in comparison with clinicopathological information. We counted small necrotic foci (micronecrosis) as necrosis, in addition to massive necrosis that had been only defined as necrosis in previous studies. The reproducibility of identifying histological parameters was tested by asking five independent observers to blindly review 51 examples of PDC.

Results:

Both micronecrosis and massive necrosis corresponded to hypoxic foci expressing carbonic anhydrase IX detected by immunohistochemistry. Multivariate survival analysis showed that histological necrosis was an independent predictor of poor outcome in terms of both disease-free survival (DFS) and disease-specific survival (DSS) of PDC patients. In addition, metastatic status, and lymphatic, venous, and intrapancreatic neural invasion were independent prognostic factors for shorter DFS and metastatic status, margin status, lymphatic invasion, and intrapancreatic neural invasion were independent prognostic factors for DSS. The interobserver reproducibility of necrosis identification among the five independent observers was ‘almost perfect’ (κ-value of 0.87).

Conclusion:

Histological necrosis is a simple, accurate, and reproducible predictor of postoperative outcome in PDC patients.

Physiological and biochemical aspects of hydroxylations and demethylations catalyzed by human 2-oxoglutarate oxygenases

Pioneering work in the 1960s defined prolyl and lysyl hydroxylations as physiologically important oxygenase-catalyzed modifications in collagen biosynthesis; subsequent studies demonstrated that extracellular epidermal growth factor-like domains were hydroxylated at aspartyl and asparaginyl residues. More recent work on the hypoxia-sensing mechanism in animals has shown that prolyl and asparaginyl hydroxylation of the hypoxia-inducible transcription factor play central roles in sensing hypoxia, by regulating protein-protein interactions in an oxygen-dependent manner. The collective results imply that protein hydroxylation is more common than previously perceived. Most protein hydroxylases employ Fe(II) as a cofactor, and 2-oxoglutarate and oxygen as co-substrates. Related enzymes catalyze the demethylation of N(ɛ)-methyl lysine residues in histones and of N-methylated nucleic acids, as well as hydroxylation of 5-methyl cytosine in DNA and 5-methoxycarbonylmethyluridine at the wobble position of tRNA. The combination of new molecular biological and analytical techniques is likely to reveal further roles for oxygenase-mediated modifications to biomacromolecules.

Therapeutic manipulation of the HIF hydroxylases

The hypoxia-inducible factor (HIF) family of transcription factors is responsible for coordinating the cellular response to low oxygen levels in animals. By regulating the expression of a large array of target genes during hypoxia, these proteins also direct adaptive changes in the hematopoietic, cardiovascular, and respiratory systems. They also play roles in pathological processes, including tumorogenesis. In recent years, several oxygenases have been identified as key molecular oxygen sensors within the HIF system. The HIF hydroxylases regulate the stability and transcriptional activity of the HIF-alpha subunit by catalyzing hydroxylation of specific proline and asparaginyl residues, respectively. They require oxygen and 2-oxoglutarate (2OG) as co-substrates, and depend upon non-heme ferrous iron (Fe(II)) as a cofactor. This article summarizes current understanding of the biochemistry of the HIF hydroxylases, identifies targets for their pharmacological manipulation, and discusses their potential in the therapeutic manipulation of the HIF system.

The metal-responsive transcription factor-1 protein is elevated in human tumors

We previously identified metal-responsive transcription factor-1 (MTF-1) as a positive contributor to mouse fibrosarcoma growth through effects on cell survival, proliferation, tumor angiogenesis and extracellular matrix remodeling. In the present study, we investigated MTF-1 protein expression in human tissues by specific immunostaining of both normal and tumor tissue samples. Immunohistochemical (IHC) staining of a human tissue microarray (TMA), using a unique anti-human MTF-1 antibody, indicated constitutive MTF-1 expression in most normal tissues, with liver and testis displaying comparatively high levels of expression. Nevertheless, MTF-1 protein levels were found to be significantly elevated in diverse human tumor types, including breast, lung and cervical carcinomas. IHC analysis of a separate panel of full-size tissue sections of human breast cancers, including tumor and normal adjacent, surrounding tissue, confirmed and extended the results of the TMA analysis. Taken with our previous findings, this new study suggests a role for MTF-1 in human tumor development, growth or spread. Moreover, the study suggests that MTF-1 could be a novel therapeutic target that offers the opportunity to manipulate metal or redox homeostasis in tumor cells.

Aryl hydrocarbon nuclear translocator (hypoxia inducible factor 1beta) activity is required more during early than late tumor growth

c4 is a derivative of the mouse hepatoma cell line, Hepa-1, that harbors a mutation in the aryl hydrocarbon receptor nuclear translocator gene (Arnt, or hypoxia inducible factor 1beta [HIF-1beta]) leading to loss of activity. Clone 3 cells were generated by introducing a doxycycline-repressible Arnt expression vector into c4 cells. Clone 3 cells were injected subcutaneously into immunosuppressed mice, which were treated with doxycyline (a) throughout the growth of the subsequent tumor xenografts, or (b) from day 7 through to the end of the experiment (day 30), or not treated (c). Tumors in all groups grew exponentially between days 14 and 30, and at rates that were indistinguishable from each other. However, tumors in group a were smaller than those of the other two groups throughout the measurable growth period, while tumor volumes in groups b and c were not significantly different from each other. The degrees of vascularity and apoptosis did not correlate with the differences in degrees of growth between the different groups. Thus, Arnt is required during the early stages of growth of the tumors but less in later stages. Since Arnt does not detectably effect the growth kinetics of Hepa-1 cells either during hypoxia or normoxia, this requirement is unlikely to reflect a direct effect of Arnt on cell proliferation, and is therefore probably a consequence of altered interaction(s) between the tumor cells and the host. These studies suggest that Arnt (and HIF-1alpha/HIF-2alpha) inhibitors will be particularly effective against smaller tumors, including micrometastases.

Stimulation of endothelial progenitor cells: a new putative effect of several cardiovascular drugs

The role of vascular endothelium in cardiovascular disorders is well recognized. Mature endothelial cells contribute to the repair of endothelial injury, but they only have a limited capacity to do so. This has led to growing interest and further investigation into circulating endothelial progenitor cells (EPCs) and their role in vascular healing, repair, and postnatal neovascularization. The current perception of vascular health is that of a balance between ongoing injury and resultant vascular repair, mediated at least in part by circulating EPCs. Circulating EPCs play an important role in accelerating endothelialization at areas of vascular damage, and EPC enumeration is a viable strategy for assessing reparative capacity. Recent studies have shown that EPCs are affected both in number and function by several cardiovascular risk factors as well as various cardiovascular disease states, such as hypertension, hypercholesterolemia, and coronary artery disease. The present review summarizes the most relevant studies on the effects of cardiovascular drugs on vascular function and EPCs, focusing on their mechanisms of action.

Multiscale models of angiogenesis

Vascular disease, cancer, stroke, neurodegeneration, diabetes, inflammation, asthma, obesity, arthritis--the list of conditions that involve angiogenesis reads like main chapters in a book on pathology. Angiogenesis, the growth of capillaries from preexisting vessels, also occurs in normal physiology, in response to exercise or in the process of wound healing.Why and when is angiogenesis prevalent? What controls the process? How can we intelligently control it? These are the key questions driving researchers in fields as diverse as cell biology, oncology, cardiology, neurology, biomathematics, systems biology, and biomedical engineering. As bioengineers, we approach angiogenesis as a complex, interconnected system of events occurring in sequence and in parallel, on multiple levels, triggered by a main stimulus, e.g., hypoxia.

Clinical implications of hypoxia inducible factor in renal cell carcinoma

Management of renal cell carcinoma (RCC) has made considerable strides in the past decade, due in large part to identification of the von Hippel Lindau (VHL) tumor suppressor as a negative regulator of hypoxia inducible factor alpha (HIF-alpha) protein expression. Stabilization of HIF-alpha appears to be critical for renal tumorigenesis, and is observed even in VHL-independent RCC. Thus, an understanding of the pathways that regulate expression and activation of the different HIF-alpha isoforms is key to delineating the mechanism of renal transformation and for the development of novel therapeutics. A number of agents targeting HIF-alpha or its transcriptionally-regulated genes have shown promise in treatment of RCC. However, more effective treatment strategies are still needed. This report provides a directed review of recent discoveries defining the role of HIF in renal tumorigenesis and their relevance to the clinical advances in targeted therapy for advanced RCC.

Synthesis of Neolamellarin A, an Inhibitor of Hypoxia-Inducible Factor-1

Neolamellarin A, a metabolite isolated from the sponge Dendrilla nigra, was found to inhibit hypoxia-inducible factor-1 (HIF-1) activation by 26% at 10 μM concentration and inhibition of HIF-1 has become a major antitumor molecular target. Herein the first synthesis of neolamellarin A is described. The synthetic strategy features the condensation of vinylogous amide with aminomalonate to construct the 3,4-bis(4-methoxyphenyl)-1 H-pyrrole core and the subsequent acylation and deprotection rendered the target compound in 18% over all yield.

Marine Natural Products as Inhibitors of Hypoxic Signaling in Tumors

Marine natural products have become a major source of new chemical entities in the discovery of potential anticancer agents that potently suppress various antitumor molecular targets. As a consequence of insufficient vascularization, hypoxic regions form within rapidly growing solid tumor masses. Specific alterations of gene expression in these hypoxic tumor cells help facilitate the survival and metastatic spread of solid tumors. The transcriptional response to cellular hypoxia is primarily mediated by the transcription factor hypoxia-inducible factor-1 (HIF-1) that regulates the expression of more than 100 genes involved in cellular adaptation and survival under hypoxic stress. Clinical studies in cancer patients indicate that HIF-1 activation is directly correlated with advanced disease stages and treatment resistance. HIF-1 has emerged as an important tumor-selective molecular target for anticancer drug discovery. As a result, natural product-based inhibitors of HIF-1 activation have been identified from plants and microorganisms. Recently, structurally unique natural products from marine sponges, crinoids, and algae have been identified as HIF-1 activation inhibitors. The US National Cancer Institute's Open Repository of marine invertebrate and algae extracts has proven to be a valuable source of natural product HIF-1 inhibitors. Among the active compounds identified, certain marine natural products have also been shown to suppress the hypoxic induction of HIF-1 target genes such as vascular endothelial growth factor (VEGF). Some of these marine HIF-1 inhibitors act by interfering with the generation of mitochondrial signaling molecules in hypoxic cells. However, the precise mechanisms of action for many newly identified marine natural product HIF-1 inhibitors remain unresolved.