Molecular pathways for cancer angioprevention

In vitro photochemoprotective potential of emulsion containing the ethyl acetate fraction from Eugenia neoverrucosa (Myrtaceae)

This work aimed to study the chemical composition and evaluate the in vitro photochemoprotective potential of an emulsion containing bioactive plant material obtained from Eugenia neoverrucosa Sobral leaves. The ethyl acetate fraction (EAF) was selected for its high content of total phenolics and high antioxidant capacity. Chemical analysis using 1D/2D nuclear magnetic resonance spectroscopy identified three ursane-type pentacyclic triterpenoids - corosolic acid (1), 3-O-α-L-arabinopyranosyl-pomolic acid (2), and pomolic acid (3) - and one phenolic acid, gallic acid (4). EAF showed no cytotoxicity and exhibited photochemoprotective and cytoprotective activities, reducing reactive oxygen species (ROS) generation and preserving catalase activity in UVB-irradiated L929 fibroblasts. Emulsions containing EAF, the synthetic UVB filter homosalate (HMS), and their combination were developed and evaluated. EAF emulsion enhanced antioxidant activity, while its combination with HMS improved UVB absorption and photoprotective efficacy. These findings highlight EAF's potential as a multifunctional ingredient for innovative photoprotective formulations to mitigate oxidative stress and promote skin health.

Antiangiogenic Potential of an Olive Oil Extract: Insights from a Proteomic Study

Extra virgin olive oil (EVOO), a staple of the Mediterranean diet, is rich in phenolic compounds recognized for their potent bioactive effects, including anticancer and anti-inflammatory properties. However, its effects on vascular health remain relatively unexplored. In this study, we examined the impact of a "picual" EVOO extract from Jaén, Spain, on endothelial cells. Proteomic analysis revealed the modulation of angiogenesis-related processes. In subsequent in vitro experiments, the EVOO extract inhibited endothelial cell migration, adhesion, invasion, ECM degradation, and tube formation while inducing apoptosis. These results provide robust evidence of the extract's antiangiogenic potential. Our findings highlight the potential of EVOO extracts in mitigating angiogenesis-related pathologies, such as cancer, macular degeneration, and diabetic retinopathy.

The Long Telling Story of "Endothelial Progenitor Cells": Where Are We at Now?

Endothelial progenitor cells (EPCs): The name embodies years of research and clinical expectations, but where are we now? Do these cells really represent the El Dorado of regenerative medicine? Here, past and recent literature about this eclectic, still unknown and therefore fascinating cell population will be discussed. This review will take the reader through a temporal journey that, from the first discovery, will pass through years of research devoted to attempts at their definition and understanding their biology in health and disease, ending with the most recent evidence about their pathobiological role in cardiovascular disease and their recent applications in regenerative medicine.

Sanguinarine Inhibition of TNF-α-Induced CCL2, IKBKE/NF-κB/ERK1/2 Signaling Pathway, and Cell Migration in Human Triple-Negative Breast Cancer Cells

Angiogenesis is a process that drives breast cancer (BC) progression and metastasis, which is linked to the altered inflammatory process, particularly in triple-negative breast cancer (TNBC). In targeting inflammatory angiogenesis, natural compounds are a promising option for managing BC. Thus, this study was designed to determine the natural alkaloid sanguinarine (SANG) potential for its antiangiogenic and antimetastatic properties in triple-negative breast cancer (TNBC) cells. The cytotoxic effect of SANG was examined in MDA-MB-231 and MDA-MB-468 cell models at a low molecular level. In this study, SANG remarkably inhibited the inflammatory mediator chemokine CCL2 in MDA-MB-231 and MDA-MB-468 cells. Furthermore, qRT-PCR confirmed with Western analysis studies showed that mRNA CCL2 repression was concurrent with reducing its main regulator IKBKE and NF-κB signaling pathway proteins in both TNBC cell lines. The total ERK1/2 protein was inhibited in the more responsive MDA-MB-231 cells. SANG exhibited a higher potential to inhibit cell migration in MDA-MB-231 cells compared to MDA-MB-468 cells. Data obtained in this study suggest a unique antiangiogenic and antimetastatic effect of SANG in the MDA-MB-231 cell model. These effects are related to the compound’s ability to inhibit the angiogenic CCL2 and impact the ERK1/2 pathway. Therefore, SANG use may be recommended as a component of the therapeutic strategy for TNBC.

Antiaging Mechanism of Natural Compounds: Effects on Autophagy and Oxidative Stress

Aging is a natural biological process that manifests as the progressive loss of function in cells, tissues, and organs. Because mechanisms that are meant to promote cellular longevity tend to decrease in effectiveness with age, it is no surprise that aging presents as a major risk factor for many diseases such as cardiovascular disease, neurodegenerative disorders, cancer, and diabetes. Oxidative stress, an imbalance between the intracellular antioxidant and overproduction of reactive oxygen species, is known to promote the aging process. Autophagy, a major pathway for protein turnover, is considered as one of the hallmarks of aging. Given the progressive physiologic degeneration and increased risk for disease that accompanies aging, many studies have attempted to discover new compounds that may aid in the reversal of the aging process. Here, we summarize the antiaging mechanism of natural or naturally derived synthetic compounds involving oxidative stress and autophagy. These compounds include: 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) derivatives (synthetic triterpenoids derived from naturally occurring oleanolic acid), caffeic acid phenethyl ester (CAPE, the active ingredient in honey bee propolis), xanthohumol (a prenylated flavonoid identified in the hops plant), guggulsterone (a plant steroid found in the resin of the guggul plant), resveratrol (a natural phenol abundantly found in grape), and sulforaphane (a sulfur-containing compound found in cruciferous vegetables).

A Polyphenol-Rich Extract of Olive Mill Wastewater Enhances Cancer Chemotherapy Effects, While Mitigating Cardiac Toxicity

Cardiovascular toxicity remains one of the most adverse side effects in cancer patients receiving chemotherapy. Extra-virgin olive oil (EVOO) is rich in cancer preventive polyphenols endowed with anti-inflammatory, anti-oxidant activities which could exert protective effects on heart cells. One very interesting derivative of EVOO preparation is represented by purified extracts from olive mill waste waters (OMWW) rich in polyphenols. Here, we have investigated the anti-cancer activity of a OMWW preparation, named A009, when combined with chemotherapeutics, as well as its potential cardioprotective activities. Mice bearing prostate cancer (PCa) xenografts were treated with cisplatin, alone or in combination with A009. In an in vivo model, we found synergisms of A009 and cisplatin in reduction of prostate cancer tumor weight. Hearts of mice were analyzed, and the mitochondria were studied by transmission electron microscopy. The hearts of mice co-treated with A009 extracts along with cisplatin had reduced mitochondria damage compared to the those treated with chemotherapy alone, indicating a cardioprotective role. To confirm the in vivo results, tumor cell lines and rat cardiomyocytes were treated with cisplatin in vitro, with and without A009. Another frequently used chemotherapeutic agent 5-fluorouracil (5-FU), was also tested in this assay, observing a similar effect. In vitro, the combination of A009 with cisplatin or 5-FU was effective in decreasing prostate and colon cancer cell growth, while it did not further reduce growth of rat cardiomyocytes also treated with cisplatin or 5-FU. A009 cardioprotective effects towards side effects caused by 5-FU chemotherapy were further investigated, using cardiomyocytes freshly isolated from mice pups. A009 mitigated toxicity of 5-FU on primary cultures of mouse cardiomyocytes. Our study demonstrates that the polyphenol rich purified A009 extracts enhance the effect of chemotherapy in vitro and in vivo, but mitigates chemotherpy adverse effects on heart and on isolated cardiomyocytes. Olive mill waste water extracts could therefore represent a potential candidate for cardiovascular prevention in patients undergoing cancer chemotherapy.

Inhibition of neovascularisation in human endothelial cells using anti NRP-1 nanobody fused to truncated form of diphtheria toxin as a novel immunotoxin

Neuropilin-1 (NRP-1) regulates a range of physiological and pathological processes, including angiogenesis. Targeting of NRP1 is considered a significant approach in cancer therapy. In the present study, a novel antiNRP1 immunotoxin (αNRP1 IT) was developed by genetic fusion of a single domain (VHH) anti-NRP-1 antibody fragment to a truncated diphtheria toxin. The αNRP1 IT was expressed into bacterial cells as an inclusion body (IB). Expression of αNRP1 IT was confirmed by SDS-PAGE and western blotting. Recombinant αNRP1 IT was purified using nickel affinity chromatography. Toxicity and antiangiogenesis effect of αNRP1 IT was investigated both in vitro and in vivo. Results showed that αNRP1 IT significantly reduced the viability of human umbilical vein endothelial cell line (HUVEC) (p < .05). The αNRP1 IT significantly inhibited tube formation of HUVEC cells (p < .001). Furthermore, αNRP1 IT inhibited angiogenesis in Chick Chorioallantoic Membrane (CAM) Assay. These data suggest the potential of αNRP1 IT as a novel therapeutic in targeted cancer therapy.

Squalene deters drivers of RCC disease progression beyond VHL status

Identifying drug candidates to target cellular events/signaling that evades von Hippel-Lindau tumor suppressor (VHL) gene interaction is critical for the cure of renal cell carcinoma (RCC). Recently, we characterized a triterpene-squalene derived from marine brown alga. Herein, we investigated the potential of squalene in targeting HIF-signaling and other drivers of RCC progression. Squalene inhibited cell proliferation, induced cell dealth and reverted the cells' metastatic state (migration, clonal expansion) independent of their VHL status. Near-identical inhibition of HIF-1α and HIF-2α and the regulation of downstream targets in VHL wild type and mutant cell lines demonstrated squalene efficacy beyond VHL-HIF interaction. In a rat model of chemically induced RCC, squalene displayed chemopreventive capabilities by substantial reversal of lipid peroxidation, mitochondrial redox regulation, maintaining ∆ψ_m, inflammation [Akt, nuclear factor κB (NF-κB)], angiogenesis (VEGFα), metastasis [matrix metalloproteinase 2 (MMP-2)], and survival (Bax/Bcl2, cytochrome-c, Casp3). Squalene restored glutathione, glutathione reductase, glutathione-s-transferase, catalase, and superoxide dismutase and stabilized alkaline phosphatase, alkaline transaminase, and aspartate transaminase. The correlation of thiobarbituric acid reactive substance with VEGF/NF-κB and negative association of GSH with Casp3 show that squalene employs reduction in ROS regulation. Cytokinesis-block micronuclei (CBMN) assay in VHL^wt/mut cells revealed both direct and bystander effects of squalene with increased micronucleus (MN) frequency. Clastogenicity analysis of rat bone marrow cells demonstrated an anti-clastogenic effect of squalene, with increased polychromatic erythrocytes (PCEs), decreased MNPCE,s and MN normochromatic erythrocytes. Squalene could effectively target HIF signaling that orchestrate RCC evolution. The efficacy of squalene is similar in VHL^wt and VHL^mut RCC cells, and hence, squalene could serve as a promising drug candidate for an RCC cure beyond VHL status and VHL-HIF interaction dependency. Summary: Squalene derived from marine brown algae displays strong anti-cancer (RCC) activity, functionally targeting HIF-signaling pathway, and affects various cellular process. The significance of squalene effect for RCC is highlighted by its efficiency beyond VHL status, designating itself a promising drug candidate. Graphical abstract.

Fisetin inhibits vascular endothelial growth factor-induced angiogenesis in retinoblastoma cells

Fisetin is a small phytochemical molecule with antitumor activity. Angiogenesis is a basic process that occurs during tumor growth and metastasis. The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway is a key regulator of angiogenesis. The aim of the present study was to evaluate whether fisetin affects angiogenesis through the VEGFR pathway. In the present study, Y79 cells were treated with 100 ng/ml VEGF in the presence of fisetin at concentrations of 0, 25, 50 and 100 µM. A Cell Counting Kit-8 assay was used to detect proliferation and the Transwell and Matrigel assays were used to assess cell migration and invasion, respectively. Reverse transcription-quantitative polymerase chain reaction analysis was applied to measure the expression level of VEGFR mRNA and western blot analysis was used to measure the protein expression of VEGFR. An immunofluorescence assay was used to detect the expression of VEGFR. Angiogenesis in vitro was assessed by a tube formation assay. The results demonstrated that fisetin significantly inhibited the proliferation of Y79 cells in a time- and dose-dependent manner. Fisetin also inhibited the migration and invasion of Y79 cells in a dose-dependent manner. Furthermore, fisetin inhibited the expression of VEGFR in Y79 cells in a dose-dependent manner and tumor angiogenesis in vitro. Thus, fisetin was found to inhibit angiogenesis via inhibition of the VEGF/VEGFR signaling pathway, and could be used as a candidate drug to inhibit angiogenesis in retinoblastoma.

Ardisia crispa root hexane fraction suppressed angiogenesis in human umbilical vein endothelial cells (HUVECs) and in vivo zebrafish embryo model

Ardisia crispa Thunb. A. DC. (Primulaceae) has been used extensively as folk-lore medicine in South East Asia including China and Japan to treat various inflammatory related diseases. Ardisia crispa root hexane fraction (ACRH) has been thoroughly studied by our group and it has been shown to exhibit anti-inflammatory, anti-hyperalgesic, anti-arthritic, anti-ulcer, chemoprevention and suppression against inflammation-induced angiogenesis in various animal model. Nevertheless, its effect against human endothelial cells in vitro has not been reported yet. Hence, the aim of the study is to investigate the potential antiangiogenic property of ACRH in human umbilical vein endothelial cells (HUVECs) and zebrafish embryo model. ACRH was separated from the crude ethanolic extract of the plant's root in prior to experimental studies. MTT assay revealed that ACRH exerted a concentration-dependent antiproliferative effect on HUVEC with the IC₅₀ of 2.49 ± 0.04 μg/mL. At higher concentration (10 μg/mL), apoptosis was induced without affecting the cell cycle distribution. Angiogenic properties including migration, invasion and differentiation of HUVECs, evaluated via wound healing, trans-well invasion and tube formation assay respectively, were significantly suppressed by ACRH in a concentration-dependent manner. Noteworthily, significant antiangiogenic effects were observed even at the lowest concentration used (0.1 μg/mL). Expression of proMMP-2, vascular endothelial growth factor (VEGF)-C, VEGF-D, Angiopoietin-2, fibroblast growth factor (FGF)-1, FGF-2, Follistatin, and hepatocyte growth factor (HGF) were significantly reduced in various degrees by ACRH. The ISV formation in zebrafish embryo was significantly suppressed by ACRH at the concentration of 5 μg/mL. These findings revealed the potential of ACRH as antiangiogenic agent by suppressing multiple proangiogenic proteins. Thus, it can be further verified via the transcription of these proteins from their respective DNA, in elucidating their exact pathways.

A critical review on anti-angiogenic property of phytochemicals

Angiogenesis, a process involved in neovascularization, has been found to be associated with several metabolic diseases like cancer, retinopathy etc. Thus, currently, the focus on anti-angiogenic therapy for treatment and prevention of diseases has gained significant attention. Currently available Food and Drug Administration (FDA) approved drugs are targeting either vascular endothelial growth factor or it's receptor, but in the long term, these approaches were shown to cause several side effects and the chances of developing resistance to these drugs is also high. Therefore, identification of safe and cost-effective anti-angiogenic molecules is highly imperative. Over the past decades, dietary based natural compounds have been studied for their anti-angiogenic potential which provided avenues in improving the angiogenesis based therapy. In this review, major emphasis is given to the molecular mechanism behind anti-angiogenic effect of natural compounds from dietary sources.

Synthesis and antiangiogenic activity study of new hop chalcone Xanthohumol analogues

Angiogenesis induction is a hallmark of cancer. Antiangiogenic properties of Xanthohumol (XN), a naturally occurring prenylated chalcone from hops, have been widely reported. Here we describe the synthesis and study the antiangiogenic activity in vitro of a series of XN derivatives, where different substituents on the B-ring of the chalcone scaffold were inserted. The new XN derivatives inhibited human umbilical-vein endothelial cell (HUVEC) proliferation, adhesion, migration, invasion and their ability to form capillary-like structures in vitro at 10 μM concentration. The preliminary results indicate that the phenolic OH group in R, present in natural XN, is not necessary for having antiangiogenic activity. In fact, the most effective compound from this series, 13, was characterized by a para-methoxy group in R and a fluorine atom in R₂ on B-ring. This study paves the way for future development of synthetic analogues of XN to be used as cancer angiopreventive and chemopreventive agents.

Endothelial progenitor cells promote tumor growth and progression by enhancing new vessel formation

Tumor growth and progression require new blood vessel formation to deliver nutrients and oxygen for further cell proliferation and to create a neovascular network exit for tumor cell metastasis. Endothelial progenitor cells (EPCs) are a bone marrow (BM)-derived stem cell population that circulates in the peripheral circulation and homes to the tumor bed to participate in new blood vessel formation. In addition to structural support to nascent vessels, these cells can also regulate the angiogenic process by paracrine secretion of a number of proangiogenic growth factors and cytokines, thus playing a crucial role in tumor neovascularization and development. Inhibition of EPC-mediated new vessel formation may be a promising therapeutic strategy in tumor treatment. EPC-mediated neovascularization is a complex process that includes multiple steps and requires a series of cytokines and modulators, thus understanding the underlying mechanisms may provide anti-neovasculogenesis targets that may be blocked for the prevention of tumor development. The present review stresses the process and contribution of EPCs to the formation of new blood vessels in solid tumors, in an attempt to gain an improved understanding of the underlying cellular and molecular mechanisms involved, and to provide a potential effective therapeutic target for cancer treatment.

Cinnamon extract reduces VEGF expression via suppressing HIF-1α gene expression and inhibits tumor growth in mice

Although many anti-VEGF agents are available for cancer treatment, side effects of these agents limit their application for cancer treatment and prevention. Here we studied the potential use of a diet-based agent as an inhibitor for VEGF production. Using a VEGF reporter assay, our data showed that an extract from cinnamon (CE) was a potent inhibitor of VEGF production in human cancer cells and suggested inhibition might be mediated through the suppression of HIF-1α gene expression and protein synthesis. Furthermore, CE treatment was found to inhibit expression and phosphorylation of STAT3 and AKT, which are key factors in the regulation of HIF-1α expression, and significantly reduce angiogenesis potential of cancer cells by migration assay. Consistent with these results, we observed significant suppression of VEGF expression, blood vessel formation, and tumor growth in a human ovarian tumor model in mice treated with CE. Cinnamaldehyde, a major component in cinnamon, was identified as one active component in CE that inhibits VEGF expression. Taken together, our findings provide a novel mechanism underlying anti-angiogenic and anti-tumor actions of CE and support the potential use of CE in cancer prevention and treatment. © 2016 Wiley Periodicals, Inc.

Prognostic Significance of VEGF after Twenty-Year Follow-up in a Randomized Trial of Fenretinide in Non-Muscle-Invasive Bladder Cancer

Non-muscle-invasive bladder cancer (NMIBC) may progress to muscle-invasive disease, but no effective preventive treatments are available. In addition, no reliable prognostic biomarkers have been identified. We assessed the long-term effect of the oral retinoid fenretinide and the prognostic value of circulating VEGF levels. We updated through the Tumor Registry the vital status of 99 patients with resected Ta/T1 bladder tumors who were recruited in a randomized trial of 2 years of fenretinide or no treatment in 1993-1994. Serum VEGF levels measured at baseline and 12 months were available in a subgroup of 62 patients. After a median of 20.5 years, 54 subjects died, 35 of any cancer and 14 of bladder cancer. Neither overall survival (OS), nor cancer survival (CS) or bladder cancer survival (BCS) was affected by fenretinide (log-rank P ≥ 0.2). DNA aneuploidy in bladder washing was associated with shorter OS (P = 0.02), CS (P = 0.05), and BCS (P = 0.09). Subjects with baseline VEGF levels in the top quintile (≥350 pg/mL) had a significantly shorter OS (P = 0.01), CS (P = 0.02), and BCS (P = 0.008). The trend across quintiles of VEGF was significant for BCS (P = 0.007). Multivariate analyses showed that, in addition to smoking status, VEGF level in the top quintile was an independent prognostic factor for OS (HR = 2.7; 95% CI, 1.1-6.5), CS (HR = 3.3; 95% CI, 1.1-9.4) and BCS (HR = 8.9; 95% CI,1.3-61). Fenretinide did not affect the long-term outcome of patients with NMIBC. High serum VEGF level was a significant predictor of overall and cancer death and may help to identify high-risk subjects who may benefit from a preventive therapy. Cancer Prev Res; 9(6); 437-44. ©2016 AACR.

Spatially resolved optical and ultrastructural properties of colorectal and pancreatic field carcinogenesis observed by inverse spectroscopic optical coherence tomography

Field carcinogenesis is the initial stage of cancer progression. Understanding field carcinogenesis is valuable for both cancer biology and clinical medicine. Here, we used inverse spectroscopic optical coherence tomography to study colorectal cancer (CRC) and pancreatic cancer (PC) field carcinogenesis. Depth-resolved optical and ultrastructural properties of the mucosa were quantified from histologically normal rectal biopsies from patients with and without colon adenomas (n=85) as well as from histologically normal peri-ampullary duodenal biopsies from patients with and without PC (n=22). Changes in the epithelium and stroma in CRC field carcinogenesis were separately quantified. In both compartments, optical and ultra-structural alterations were consistent. Optical alterations included lower backscattering (μb) and reduced scattering (μs') coefficients and higher anisotropy factor g. Ultrastructurally pronounced alterations were observed at length scales up to ∼450  nm, with the shape of the mass density correlation function having a higher shape factor D, thus implying a shift to larger length scales. Similar alterations were found in the PC field carcinogenesis despite the difference in genetic pathways and etiologies. We further verified that the chromatin clumping in epithelial cells and collagen cross-linking caused D to increase in vitro and could be among the mechanisms responsible for the observed changes in epithelium and stroma, respectively.

The antiangiogenic activities of ethanolic crude extracts of four Salvia species

Background

Angiogenesis is one of cancer hallmarks that are required for both cancer progression and metastasis. In this study we examined the antiangiogenic properties of the ethanolic crude extracts of four Salvia species grown in Jordan.

Methods

The direct antiangiogenic activity was evaluated using various models: ex vivo rat aortic ring assay, in vitro assessment of HUVEC proliferation and migration, and in vivo CAM assay, while we used the changes in the expression of HIF-1α and VEGF in breast cancer cells (MCF 7) as an indicative for the indirect antiangiogenic activity.

Results

All four crude extracts showed a potential antiangiogenic activity in the rat aortic assay, however two species were found to be cytotoxic against Fibroblast cell line (PLF); the finding that caused the exclusion of these two extracts from further studies. Of the two remaining extracts, S. triloba showed very promising direct and indirect antiangiogenic activities. S. triloba inhibited the HUVEC proliferation with an IC₅₀ of 90 μg/mL and HUVEC migration by 82% at 150 μg/mL. Furthermore, the in vivo CAM assay also illustrated the high impact of S. triloba against the newly formed vessel in the chicken embryonic membrane. Interestingly, the S. triloba inhibited the expression of VEGF at the mRNA and protein and the HIF-1α mRNA in the MCF 7 breast cancer cells under both normoxic and hypoxic conditions.

Conclusions

Taken together, all these findings of the direct and indirect angiogenic investigations nominated S. triloba as a highly potent antiangiogenic plant that may have chemotherapeutic and/or chemoprevention potentials.

Marine algal carotenoids inhibit angiogenesis by down-regulating FGF-2-mediated intracellular signals in vascular endothelial cells

Discovery of natural compounds as effective angiogenesis inhibitors has become an important approach in the prevention of cancer. We previously demonstrated the anti-angiogenic potential of two marine algal carotenoids, fucoxanthin and siphonaxanthin. In this study, we evaluated the molecular mechanisms of the anti-angiogenic activity of those two carotenoids using human umbilical vein endothelial cells. This study showed that both fucoxanthin and siphonaxanthin suppress the mRNA expression of fibroblast growth factor 2 (FGF-2) and its receptor (FGFR-1) as well as their trans-activation factor, EGR-1. But, the mRNA expression of VEGFR-2 did not show significant effect by those two carotenoids. Further, those two marine algal carotenoids down-regulate the phosphorylation of FGF-2-mediated intracellular signaling proteins such as ERK1/2 and Akt. Inhibition of FGF-2-mediated intracellular signaling proteins by those carotenoids represses the migration of endothelial cells as well as their differentiation into tube-like structures on Matrigel. These results demonstrate for the first time the possible molecular mechanism underlying the anti-angiogenic effects of fucoxanthin and siphonaxanthin and suggest that these effects are due to the down-regulation of signal transduction by FGFR-1. Our findings imply a new insight into the novel bio-functional property of marine algal carotenoids which should improve current anti-angiogenic therapies in the treatment of cancer and other pro-angiogenic diseases.

Advances in biophotonics detection of field carcinogenesis for colon cancer risk stratification

The process of neoplastic transformation of the colon involves a progression through hyperproliferative epithelium through the aberrant crypt foci→small adenoma→large adenoma→invasive cancer→metastatic disease. These are orchestrated by sequential genetic and epigenetic events which provide the underpinnings of cellular alterations such as early induction in proliferation/suppression of apoptosis, along with the late stage increase in invasiveness. Colorectal cancer (CRC) averages 49-111 mutations per tumor encompassing 10-15 critical signaling pathways[1]. Accumulating such a high number of mutations requires a fertile mutational field, which is the hallmark of colon carcinogenesis.

While genetic susceptibility to colorectal cancer is well-known, at least half of the risk is believed to be due to exogeneous factors (e.g., obesity, diet, exercise). Understanding these risk factors represents a promising mode of tailoring screening modality and intensity. However, previous attempts using these factors (i.e., NCI risk calculator) have only been modestly successful with an area under receiver operating characteristics (ROC) curve (AUC) of just 0.61. One of the most important concepts is that risk is the interaction between these genetic and environmental components and is driven by the variety of polymorphisms. Thus, predicting risk is difficult given the complexity. On the other hand, the colonic mucosa represents the end product of the complex interplay between these multiple factors. The power of field carcinogenesis is that it reflects this interplay between genetics and environment.

Anti-angiogenic activity of the flavonoid precursor 4-hydroxychalcone

Angiogenesis, the growth of new blood vessels, is necessary for cancerous tumors to keep growing and spreading. Suppression of abnormal angiogenesis may provide therapeutic strategies for the treatment of angiogenesis-dependent disorders. In the present study, we describe the in vitro and in vivo anti-angiogenic activities of the flavonoid precursor 4-hydroxychalcone (Q797). This chalcone (22μg/ml) suppressed several steps of angiogenesis, including endothelial cell proliferation, migration and tube formation without showing any signs of cytotoxicity. Moreover, we found a selective effect on activated endothelial cells, in particular with resting endothelial cells and the human epithelial tumor cell lines (HeLa, MCF-7, A549). In addition, Q797 was able to modulate both vascular endothelial growth factor (VEGF)- and basic fibroblast growth factor (FGF)- induced phosphorylation of extracellular signal-regulated kinase (ERK)-1/-2 and Akt kinase. It did not influence the nuclear translocation of p65 subunit of the nuclear factor-κB (NF-κB) when human endothelial cells were stimulated with tumor necrosis factor (TNF)-α. Taken together this indicates that the Q797-mediated inhibition of in vitro angiogenic features of endothelial cells is most likely caused by suppression of growth factor pathways. The potent inhibitory effect of Q797 on bFGF-driven neovascularization was also demonstrated in vivo using the chick chorioallantoic membrane (CAM) assay. In summary, this chalcone could serve as a new leading structure in the discovery of new potent synthetic angiogenesis inhibitors.

Tumor angiogenesis as a target for dietary cancer prevention

Between 2000 and 2050, the number of new cancer patients diagnosed annually is expected to double, with an accompanying increase in treatment costs of more than $80 billion over just the next decade. Efficacious strategies for cancer prevention will therefore be vital for improving patients' quality of life and reducing healthcare costs. Judah Folkman first proposed antiangiogenesis as a strategy for preventing dormant microtumors from progressing to invasive cancer. Although antiangiogenic drugs are now available for many advanced malignancies (colorectal, lung, breast, kidney, liver, brain, thyroid, neuroendocrine, multiple myeloma, myelodysplastic syndrome), cost and toxicity considerations preclude their broad use for cancer prevention. Potent antiangiogenic molecules have now been identified in dietary sources, suggesting that a rationally designed antiangiogenic diet could provide a safe, widely available, and novel strategy for preventing cancer. This paper presents the scientific, epidemiologic, and clinical evidence supporting the role of an antiangiogenic diet for cancer prevention.

Neo-angiogenesis and the premalignant micro-circulatory augmentation of early colon carcinogenesis

Spectroscopic techniques have demonstrated that in the microscopically normal mucosa, there is an increase in mucosal micro-circulation in patients harboring neoplasia elsewhere in the colon (i.e. marker of field carcinogenesis). However, the physiological and molecular basis of this early increase in blood supply (EIBS) has not been elucidated. We, therefore, investigated the microvessel density (MVD) and angiogenic gene expression in the premalignant colonic mucosa from the well-validated azoxymethane (AOM)-treated rat experimental model of colon carcinogenesis. Fisher 344 rats were treated with AOM (15 mg/kg i.p.) or saline and euthanized 14 weeks later (a time-point that precedes carcinoma development). Colon sections were studied for MVD via immunohistochemical assessment for CD31 and location was compared with optical assessment of mucosal hemoglobin with low-coherence enhanced backscattering spectroscopy (LEBS). Finally, we performed a pilot real-time PCR angiogenesis microarray (84 genes) from the microscopically normal colonic mucosa of AOM and age-matched saline treated rats. AOM treatment increased MVD in both the mucosa and submucosa of the rats (125% increase in mucosa; p<0.007, and 96% increase in submucosa; p<0.02) but the increase was most pronounced at the cryptal base consistent with the LEBS data showing maximal hemoglobin augmentation at 200-225 μm depth. Microarray analysis showed striking dysregulation of angiogenic and anti-angiogenic factors. We demonstrate, for the first time, that neo-angiogenesis occurs in the microscopically normal colonic mucosa and was accentuated at the bottom of the crypt. This finding has potential implications as a biomarker for risk-stratification and target for chemoprevention.

The biflavonoid amentoflavone inhibits neovascularization preventing the activity of proangiogenic vascular endothelial growth factors

The proangiogenic members of VEGF family and related receptors play a central role in the modulation of pathological angiogenesis. Recent insights indicate that, due to the strict biochemical and functional relationship between VEGFs and related receptors, the development of a new generation of agents able to target contemporarily more than one member of VEGFs might amplify the antiangiogenic response representing an advantage in term of therapeutic outcome. To identify molecules that are able to prevent the interaction of VEGFs with related receptors, we have screened small molecule collections consisting of >100 plant extracts. Here, we report the isolation and identification from an extract of the Malian plant Chrozophora senegalensis of the biflavonoid amentoflavone as an antiangiogenic bioactive molecule. Amentoflavone can to bind VEGFs preventing the interaction and phosphorylation of VEGF receptor 1 and 2 (VEGFR-1,VEGFR-2) and to inhibit endothelial cell migration and capillary-like tube formation induced by VEGF-A or placental growth factor 1 (PlGF-1) at low μm concentration. In vivo, amentoflavone is able to inhibit VEGF-A-induced chorioallantoic membrane neovascularization as well as tumor growth and associated neovascularization, as assessed in orthotropic melanoma and xenograft colon carcinoma models. In addition structural studies performed on the amentoflavone·PlGF-1 complex have provided evidence that this biflavonoid effectively interacts with the growth factor area crucial for VEGFR-1 receptor recognition. In conclusion, our results demonstrate that amentoflavone represents an interesting new antiangiogenic molecule that is able to prevent the activity of proangiogenic VEGF family members and that the biflavonoid structure is a new chemical scaffold to develop powerful new antiangiogenic molecules.

Dietary chalcones with chemopreventive and chemotherapeutic potential

Chalcones are absorbed in the daily diet and appear to be promising cancer chemopreventive agents. Chalcones represent an important group of the polyphenolic family, which includes a large number of naturally occurring molecules. This family possesses an interesting spectrum of biological activities, including antioxidative, antibacterial, anti-inflammatory, anticancer, cytotoxic, and immunosuppressive potential. Compounds of this family have been shown to interfere with each step of carcinogenesis, including initiation, promotion and progression. Moreover, numerous compounds from the family of dietary chalcones appear to show activity against cancer cells, suggesting that these molecules or their derivatives may be considered as potential anticancer drugs. This review will focus primarily on prominent members of the chalcone family with an 1,3-diphenyl-2-propenon core structure. Specifically, the inhibitory effects of these compounds on the different steps of carcinogenesis that reveal interesting chemopreventive and chemotherapeutic potential will be discussed.

Novel angiogenesis inhibitory activity in cinnamon extract blocks VEGFR2 kinase and downstream signaling

As a critical factor in the induction of angiogenesis, vascular endothelial growth factor (VEGF) has become an attractive target for anti-angiogenesis treatment. However, the side effects associated with most anti-VEGF agents limit their chronic use. Identification of naturally occurring VEGF inhibitors derived from diet is a potential alternative approach, with the advantage of known safety. To isolate natural inhibitors of VEGF, we established an in vitro tyrosine kinase assay to screen for diet-based agents that suppress VEGFR2 kinase activity. We found that a water-based extract from cinnamon (cinnamon extract, CE), one of the oldest and most popular spices, was a potent inhibitor of VEGFR2 kinase activity, directly inhibiting kinase activity of purified VEGFR2 as well as mitogen-activated protein kinase- and Stat3-mediated signaling pathway in endothelial cells. As a result, CE inhibited VEGF-induced endothelial cell proliferation, migration and tube formation in vitro, sprout formation from aortic ring ex vivo and tumor-induced blood vessel formation in vivo. Depletion of polyphenol from CE with polyvinylpyrrolidone abolished its anti-angiogenesis activity. While cinnamaldehyde, a component responsible for CE aroma, had little effect on VEGFR2 kinase activity, high-performance liquid chromatography-purified components of CE, procyanidin type A trimer (molecular weight, 864) and a tetramer (molecular weight, 1152) were found to inhibit kinase activity of purified VEGFR2 and VEGFR2 signaling, implicating procyanidin oligomers as active components in CE that inhibit angiogenesis. Our data revealed a novel activity in cinnamon and identified a natural VEGF inhibitor that could potentially be useful in cancer prevention and/or treatment.

Metabolic regulation and redox activity as mechanisms for angioprevention by dietary phytochemicals

The existence of active principles in numerous foods and beverages has been recognized by traditional medicines worldwide after centuries of empirical trial. Epidemiological studies support the concepts linking diet to survival, particularly in the incidence rates of specific cancers. Molecular studies have provided evidence that a wide range of food-derived phytochemicals and other diet-associated compounds or their synthetic derivatives represent a cornucopia of potential new compounds for prevention and treatment of chronic or acute diseases. Many have entered clinical practice or are under clinical testing. A remarkable property shared by several phytochemicals is the capacity to restrain inflammation and angiogenesis, two complex physiologic processes kept under control by strict rules, which can backfire in cancer and in pathologic conditions such as metabolic, cardiovascular and neurological disorders. We termed this concept "angioprevention". Here, we discuss recent findings on the metabolic effects of several phytochemicals with anticancer properties. The different molecular targets shared by these compounds seem to converge on crosstalking signaling networks involved in controlling energy metabolism through a redox-regulated code. The redox imbalance produced in the tissue microenvironment elicits an adaptive response that seems to provide cytoprotective effects potentially beneficial in cardiovascular and neurological disorders or energy balancing effects in metabolic disorders. However, in transformed and overt tumor cells, this redox imbalance favors cell death while curbing tumor inflammation and angiogenesis, thus engaging an overall antitumor response. These concepts provide a broader framework for pharmacological application of phytochemical-derived drugs against cancer.

The role of apoptosis in radiation oncology

PURPOSE

Apoptosis, as a mode of cell death in irradiated cell populations, has been the subject of literarily hundreds if not thousands of published reports over the past few years. However, in spite of the large body of knowledge related to this subject, the role of apoptosis in determining tumor response to radiotherapy has been and remains poorly understood and controversial. Indeed, some previous reviews have suggested that apoptosis may not be important in this context. The purpose of the present review is to provide some examples of recently reported laboratory investigations that indicate that there is a reasonable expectation that the radiation-induced apoptosis observed has contributed to the tumor response.

CONCLUSIONS

We review reports in four areas of research: Molecularly targeted agents, in vivo imaging, Bcl-2 and cancer stem cells. Examples are provided in each of these areas that we believe justify a reassessment of the role that apoptosis plays in radiation oncology.

Apoptosis induction by sulfur-containing compounds in malignant and nonmalignant human cells

Plants have traditionally represented a main source for the discovery of many biologically active substances with therapeutic values. Sulfur-containing compounds exhibit pleiotropic biological effects supporting their potential use in multitargeted cancer prevention and treatment. As potential anti-cancer agents, they have been shown to inhibit or retard the growth of various cancer cells in culture and implanted tumors in vivo. The compounds significantly inhibit experimental tumorigenesis in a wide range of animal models. A critical and well-elucidated cellular mechanism involved in the anticancer activities of sulfur-containing compounds is the induction of apoptosis through the fine-tuning of orchestrated intracellular signal transduction. This review summarizes the established proapoptotic activities of sulfur-containing compounds in malignant and nonmalignant cells with a special focus on their molecular mechanisms. The potential toxicological implications of proapoptotic effects on normal cells will also be discussed.

ABT-510 is an effective chemopreventive agent in the mouse 4-nitroquinoline 1-oxide model of oral carcinogenesis

Despite numerous advances, the 5-year survival rate for head and neck squamous cell cancer (HNSCC) has remained largely unchanged. This poor outcome is due to several variables, including the development of multiple primary tumors. Therefore, it is essential to supplement early detection with preventive strategies. Using the 4-nitroquinoline 1-oxide (4-NQO) mouse model, we sought to define an appropriate dose and duration of administration that would predict the histologic timeline of HNSCC progression. Additionally, we sought to determine the timing of the onset of the angiogenic phenotype. Finally, using ABT-510 as a proof-of-principle drug, we tested the hypothesis that inhibitors of angiogenesis can slow/delay the development of HNSCC. We determined that 8 weeks of 100 microg/mL 4-NQO in the drinking water was the optimal dosage and duration to cause a sufficient incidence of hyperkeratoses, dysplasias, and HNSCC over a period of 32 weeks with minimal morbidity and mortality. Increased microvessel density and vascular endothelial growth factor expression in hyperkeratotic lesions provided evidence that the initiation of the angiogenic phenotype occurred before the development of dysplasia. Importantly, ABT-510 significantly decreased the overall incidence of HNSCC from 37.3% to 20.3% (P = 0.021) as well as the combined incidence of dysplasia and HNSCC from 82.7% to 50.6% (P < 0.001). These findings suggest that our refinement of the 4-NQO model allows for the investigation of the histologic, molecular, and biological alterations that occur during the premalignant phase of HNSCC. In addition, these data support the hypothesis that inhibitors of angiogenesis may be promising chemopreventive agents.

Grape seed extract inhibits angiogenesis via suppression of the vascular endothelial growth factor receptor signaling pathway

Blockade of angiogenesis is an important approach for cancer treatment and prevention. Vascular endothelial growth factor (VEGF) is one of the most critical factors that induce angiogenesis and has thus become an attractive target for antiangiogenesis treatment. However, most current anti-VEGF agents often cause some side effects when given chronically. Identification of naturally occurring VEGF inhibitors derived from diet would be one alternative approach with an advantage of known safety. Grape seed extract (GSE), a widely used dietary supplement, is known to have antitumor activity. In this study, we have explored the activity of GSE on VEGF receptor and angiogenesis. We found that GSE could directly inhibit the kinase activity of purified VEGF receptor 2, a novel activity of GSE that has not been characterized. GSE could also inhibit the VEGF receptor/mitogen-activated protein kinase-mediated signaling pathway in endothelial cells. As a result, GSE could inhibit VEGF-induced endothelial cell proliferation and migration as well as sprout formation from aorta ring. In vivo assay further showed that GSE could inhibit tumor growth and tumor angiogenesis of MDA-MB-231 breast cancer cells in mice. Consistent with the in vitro data, GSE treatment of tumor-bearing mice led to concomitant reduction of blood vessel density and phosphorylation of mitogen-activated protein kinase. Depletion of polyphenol with polyvinylpyrrolidone abolished the antiangiogenic activity of GSE, suggesting a water-soluble fraction of polyphenol in GSE is responsible for the antiangiogenic activity. Taken together, this study indicates that GSE is a well-tolerated and inexpensive natural VEGF inhibitor and could potentially be useful in cancer prevention or treatment.

Grape seed extract inhibits VEGF expression via reducing HIF-1alpha protein expression

Grape seed extract (GSE) is a widely consumed dietary supplement that has antitumor activity. Here, we have investigated the inhibitory effect of GSE on the expression of vascular endothelial growth factor (VEGF) and the mechanism underlying this action. We found that GSE inhibited VEGF messenger RNA (mRNA) and protein expression in U251 human glioma cells and MDA-MB-231 human breast cancer cells. GSE inhibited transcriptional activation of the VEGF gene through reducing protein but not mRNA expression of hypoxia-inducible factor (HIF) 1alpha. The inhibitory effect of GSE on HIF-1alpha expression was mainly through inhibiting HIF-1alpha protein synthesis rather than promoting protein degradation. Consistent with this result, GSE-suppressed phosphorylation of several important components involved in HIF-1alpha protein synthesis, such as Akt, S6 kinase and S6 protein. Furthermore, in the MDA-MB-231 tumor, we found that GSE treatment inhibited the expression of VEGF and HIF-1alpha and the phosphorylation of S6 kinase without altering the subcellular localization of HIF-1alpha, correlating with reduced vessel density and tumor size. Depletion of polyphenol with polyvinylpyrrolidone abolished the inhibitory activity of GSE, suggesting a water-soluble fraction of polyphenol in GSE is responsible for the inhibitory activity. Taken together, our results indicate that GSE inhibits VEGF expression by reducing HIF-1alpha protein synthesis through blocking Akt activation. This finding provides new insight into the mechanisms of anticancer activity of GSE and reveals a novel molecular mechanism underlying the antiangiogenic action of GSE.

Differential effect of sunitinib on the distribution of temozolomide in an orthotopic glioma model

Normalization of tumor vasculature by antiangiogenic agents may improve the delivery of cytotoxic drugs to the tumor, leading to more effective therapy. In this study, we used pharmacokinetic and pharmacodynamic approaches to investigate how sunitinib at different dose levels affects brain distribution of temozolomide (TMZ), and to ascertain the relationship between intratumoral TMZ concentrations and tumor vascularity in an orthotopic human glioma model. Three groups of intracerebral U87MG tumor-bearing mice were given either vehicle or sunitinib at 20 mg/kg or 60 mg/kg per day for 7 days before receiving a steady-state regimen of TMZ that consisted of an intravenous bolus and a 3-h intraarterial infusion. TMZ concentrations in plasma, normal brain, and brain tumor were determined, and several biomarkers related to the antiangiogenic activity of sunitinib were examined. TMZ distribution in the normal brain as indicated by the brain-to-plasma steady-state TMZ concentration ratios was analogous across the three treatment groups. The brain tumor-to-plasma steady-state TMZ concentration (ss C(t)/C(p)) ratio was significantly increased in the 20 mg/kg sunitinib group (0.98 +/- 0.17) compared with the control (0.76 +/- 0.17) and 60 mg/kg sunitinib (0.68 +/- 0.09) groups. The ss C(t)/C(p) ratios were significantly correlated with the vascular normalization index (VNI), derived from the expression of CD31, collagen IV, and alpha-smooth muscle actin, which represents the fraction of functioning vessels out of the total tumor vessels. In conclusion, the effect of sunitinib on the brain tumor distribution of TMZ was dose dependent and indicated that optimal tumor exposure was achieved at a lower dose and was associated with the VNI.

Angiogenesis in pre-malignant conditions

Evidence from human studies suggests that angiogenesis commences during the pre-malignant stages of cancer. Inhibiting angiogenesis may, therefore, be of potential value in preventing progression to invasive cancer. Understanding the mechanisms inducing angiogenesis in these lesions and identification of those important in human tumourigenesis are necessary to develop translational strategies that will help realise the goal of angioprevention.

Glycogen synthase kinase 3beta regulates cell death induced by synthetic triterpenoids

The induction of programmed cell death in premalignant or malignant cancer cells by chemopreventive agents could be a valuable tool to control prostate cancer initiation and progression. In this work, we present evidence that the C-28 methyl ester of the synthetic oleanane triterpenoid 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO-Me) induces cell death in androgen-responsive and unresponsive human prostate cancer cell lines at nanomolar and low micromolar concentrations. CDDO-Me induced caspase-3, caspase-8, and caspase-9 activation; poly(ADP-ribose) polymerase cleavage; internucleosomal DNA fragmentation; and loss of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction in PC3 and DU145 cells. However, caspase-3 and caspase-8 inhibition by Z-DEVD-fmk and Z-IETD-fmk, respectively, or general caspase inhibition by BOC-D-fmk or Z-VAD-fmk did not rescue loss of cell viability induced by CDDO-Me, suggesting the activation of additional caspase-independent mechanisms. Interestingly, CDDO-Me induced inactivating phosphorylation at Ser(9) of glycogen synthase kinase 3beta (GSK3beta), a multifunctional kinase that mediates essential events promoting prostate cancer development and acquisition of androgen independence. The GSK3 inhibitor lithium chloride and, more effectively, GSK3 gene silencing sensitized PC3 and DU145 prostate cancer cells to CDDO-Me cytotoxicity. These data suggest that modulation of GSK3beta activation is involved in the cell death pathway engaged by CDDO-Me in prostate cancer cells.

Inflammation, inflammatory cells and angiogenesis: decisions and indecisions

Endothelial-immune cell cross-talk goes well beyond leukocyte and lymphocyte trafficking, since immune cells are able to intimately regulate vessel formation and function. Here we review the evidence that most immune cells are capable of polarization towards a dichotomous activity either inducing or inhibiting angiogenesis. In addition to the well-known roles of tumor associated macrophages, we find that neutrophils, myeloid-derived suppressor and dendritic cells clearly have the potential for influencing tumor angiogenesis. Further, the physiological functions of NK cells suggest that these cells may also show a potentially important role in pro- or anti-angiogenesis regulation within the tumor microenvironment. At the same time many angiogenic factors influence the activity and function of immune cells that generally favor tumor survival and tolerance. Thus the immune system itself represents a major pharmaceutical target and links angiogenesis inhibition to immunotherapy.

The synthetic oleanane triterpenoid, CDDO-methyl ester, is a potent antiangiogenic agent

We show that the synthetic oleanane triterpenoid, CDDO-methyl ester (CDDO-Me; methyl 2-cyano-3,12-dioxoolean-1,9-dien-28-oate) is an effective agent for suppressing angiogenesis, both in cell culture and in vivo. The potency of CDDO-Me is particularly striking when dosed in vivo to inhibit the angiogenic effects of vascular endothelial growth factor and tumor necrosis factor-alpha in Matrigel sponge assays; activity is seen at i.p. doses of CDDO-Me as low as 0.003 mg/kg of body weight. If the Matrigel sponges are impregnated with CDDO-Me just before implantation in the mice, picomolar doses of CDDO-Me will suppress angiogenesis. CDDO-Me also inhibits growth of endothelial cells in monolayer cultures and suppresses neovascular morphogenesis in three-dimensional cultures, but significantly higher doses (50-200 nmol/L) are required. We also show antiangiogenic effects of CDDO-Me on xenografts of Kaposi's sarcoma cells in immunocompromised mice, using CD31 as a marker. Several known individual molecular targets of CDDO-Me and related triterpenoids that are relevant to all of these findings include nuclear factor-kappaB signaling, signal transducers and activators of transcription signaling, and transforming growth factor-beta signaling, as well as Keap1, the endogenous inhibitor of the transcription factor Nrf2. However, the particularly potent antiangiogenic activity seen in vivo in the present experiments suggest that CDDO-Me, as an angioprevention agent, may be interacting with an entire network of molecular and cellular targets, rather than at a single molecular locus or in a single-cell type.