Ellagitannin-rich pomegranate extract inhibits angiogenesis in prostate cancer in vitro and in vivo.

Angiogenesis is critical to tumor growth and is stimulated by tissue hypoxia due to poor oxygen delivery. In turn, cellular hypoxia leads to angiogenesis via the induction of hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) at a cellular level. Pomegranate juice and extracts, which are rich sources of ellagitannins, have been shown to have chemopreventive potential against prostate cancer, but there have been no studies on the effects of an ellagitannin-rich pomegranate extract on angiogenesis. Human prostate cancer cells (LNCaP) and human umbilical vein endothelial cells (HUVEC) were incubated with a pomegranate extract standardized to ellagitannin content (POMx), under normoxic and hypoxic conditions in vitro. Human prostate cancer cells (LAPC4) were injected subcutaneously into severe combined immunodeficient (SCID) mice and the effects of oral administration of POMx on tumor growth, microvessel density, and HIF-1alpha and VEGF expression were determined after 4 weeks of treatment. POMx inhibited the proliferation of LNCaP and HUVEC cells significantly under both normoxic and hypoxic conditions. HIF-1alpha and VEGF protein levels were also reduced by POMx under hypoxic conditions. POMx decreased prostate cancer xenograft size, tumor vessel density, VEGF peptide levels and HIF-1alpha expression after 4 weeks of treatment in SCID mice. These results demonstrate that an ellagitannin-rich pomegranate extract can inhibit tumor-associated angiogenesis as one of several potential mechanisms for slowing the growth of prostate cancer in chemopreventive applications. Further studies in humans are needed to confirm that angiogenesis can be inhibited by an ellagitannin-rich pomegranate extract administered orally as a dietary supplement.

The combination of green tea and tamoxifen is effective against breast cancer.

Epidemiologic data have suggested that green tea may prevent breast cancer. Studies in our laboratory have provided evidence that green tea extract inhibits breast cancer growth by a direct anti-proliferative effect on the tumor cells, as well as by indirect suppressive effects on the tumor-associated endothelial cells. In this study, we asked whether concurrent administration of green tea may add to the anti-tumor effects of standard breast cancer therapy. We observed that green tea increased the inhibitory effect of tamoxifen on the proliferation of the ER (estrogen receptor)-positive MCF-7, ZR75, T47D human breast cancer cells in vitro. This combination regimen was also more potent than either agent alone at increasing cell apoptosis. In animal experiments, mice treated with both green tea and tamoxifen had the smallest MCF-7 xenograft tumor size, and the highest levels of apoptosis in tumor tissue, as compared with either agent administered alone. Moreover, the suppression of angiogenesis in vivo correlated with larger areas of necrosis and lower tumor blood vessel density in treated xenografts. Green tea decreased levels of ER-alpha in tumors both in vitro and in vivo. We also observed that green tea blocked ER-dependent transcription, as well as estradiol-induced phosphorylation and nuclear localization of mitogen-activated protein kinase. To our knowledge, this study is the first to show the interaction of green tea with the ER pathway, as well as provide mechanistic evidence that the combination of green tea and tamoxifen is more potent than either agent alone in suppressing breast cancer growth. These results may lead to future improvements in breast cancer treatment and prevention.

Rabdosia rubescens inhibits breast cancer growth and angiogenesis.

Investigators have shown that PC-SPES is a potent herbal mixture which has often been used by prostate cancer patients. In this study, we examined the inhibitory effects of certain individual components of PC-SPES on the in vitro proliferation of the human breast cancer cells MDA-MB231 and the human umbilical vein endothelial cells (HUVEC). Our data showed that individual components of PC-SPES had varying suppressive effects on cellular proliferation, and that Rabdosia rubescens appeared to be the most potent agent in these assays. Apoptosis was up-regulated by Rabdosia rubescens, as seen in the caspase-9 and TUNEL assays. These effects may be mediated via both the MAPK (mitogen-activated protein kinase) and the Akt kinase pathways. In mouse experiments, the extract from Rabdosia rubescens suppressed breast cancer xenograft size and decreased the tumor vessel density. We conclude that Rabdosia rubescens may potentially be used to treat or prevent breast cancer, and that the extract from this herbal source deserves further studies.

A pilot clinical study of short-term isoflavone supplements in breast cancer patients.

Many laboratory-based studies have shown that soy can suppress breast cancer proliferation. However, given the recent controversy generated by animal experiments that soy may under certain conditions stimulate breast cancer growth, we decided to carry out a pilot clinical trial in order to elucidate any interaction(s) between short-term isoflavone supplement administration and breast cancer growth. After a core-needle biopsy established the diagnosis of breast cancer, 17 patients were administered soy isoflavone tablets for two weeks. This surgically based study provided the unique opportunity to make objective observations based on human breast cancer tissues and blood obtained prior to and after isoflavone supplement treatment in the same patient. Twenty-six historical control cases with similar characteristics to the experimental patients were selected for comparison. We observed that the apoptosis/mitosis ratios in isoflavone-treated cancer specimens were not significantly different from those of control untreated cancer specimens. Furthermore, there appeared to be a statistically nonsignificant trend towards cancer growth inhibition in the isoflavone treatment group, as manifested by higher apoptosis/mitosis ratios compared with those from the control untreated group. Ex vivo/in vitro assays using serum from breast cancer patients prior to and at the conclusion of soy treatment reveal no significant proliferative changes on both breast cancer cells and endothelial cells. We concluded that the effect of soy on breast cancer deserves further studies in larger clinical trials.

Ganoderma lucidum spore extract inhibits endothelial and breast cancer cells in vitro.

This study was conducted to investigate the anti-proliferative activities of medicinal mushroom Ganoderma lucidum (Rei-shi or Mannentake). We have identified an alcohol extract from the spore of Ganoderma lucidum that inhibits the in vitro proliferation of human umbilical vein endothelial cells and MDA-MB231 human breast cancer cells. Further fractionation of the alcohol extract revealed that the ethyl acetate fraction inhibited both cell lines in a dose-dependent manner from 2 to 40 micro g/ml. Our results suggest that the alcohol extract from the spore of Ganoderma lucidum may possess potential anti-tumor and anti-angiogenic activities.

cDNA microarray analysis of endothelial cells in response to green tea reveals a suppressive phenotype.

Green tea may prevent cancer, partially by inhibiting tumor angiogenesis. Our previous studies showed that green tea extract was effective in inhibiting breast cancer and endothelial cell proliferation in vitro, and suppressed xenograft size and decreased the tumor vessel density in vivo. Here, we set out to further investigate the molecular mechanisms of this observed angiogenesis suppression. We utilized cDNA microarray technology to profile the global changes in endothelial cellular gene expression in response to green tea. HUVEC (human umbilical vein endothelial cells) were exposed in vitro to green tea for either 6 or 48 h. Only statistically significantly differentially expressed genes were analyzed. Gene profiling demonstrated a global down-regulation of multiple genes involved in endothelial cell growth, signal transduction and oxidation, accompanied by up-regulation of several apoptotic genes. We validated these observations by showing positive correlations with biological assays of cellular proliferation, cell cycle, and apoptosis. The anti-oxidant characteristics of green tea and its metabolites were confirmed in the ORAC (oxygen radical absorbance capacity) assay. cDNA microarray revealed that green tea has an overall suppressive effect on multiple pathways in endothelial cells. This study contributes to the comprehensive analysis of the molecular effects of green tea on endothelial cells, and provides insight into genes that may be important in chemoprevention.

The effect of commonly used drugs on angiogenesis.

BACKGROUND: Within the last decade, there has been much interest in the area of tumor angiogenesis, with the advent of many new anti-angiogenic drugs undergoing testing in cancer clinical Phases II and III. Many of the cancer patients also take multiple medications for a variety of chronic illnesses. Because of possible drug-drug interactions, it is important to investigate the effect that commonly prescribed medications may have on angiogenesis. MATERIALS AND METHODS: In this pilot study, we assessed the effect of the following drugs on in vitro angiogenesis: atenolol, diltiazem, enalapril, disopyramide, mexiletine, coumadin, cimetidine and omeprazole. RESULTS & CONCLUSION: We observed that, although some of these drugs at massive doses inhibited endothelial proliferation, they did not affect in vitro angiogenesis at human therapeutic ranges.

Green tea inhibits vascular endothelial growth factor (VEGF) induction in human breast cancer cells.

Investigators have shown that green tea and its main catechin epigallocatechin-3 gallate (EGCG) may decrease the risk of cancer. Our previous study showed that green tea extract (GTE) as well as its individual catechin components inhibited MDA-MB231 breast cancer cell and human umbilical vein endothelial cell (HUVEC) proliferation. Further, GTE suppressed breast cancer xenograft size and decreased the tumor vessel density in vivo. In the current study, we investigated the effect of GTE on the major angiogenic factor vascular endothelial growth factor (VEGF) in an in vitro experiment. GTE or EGCG (40 mg/L) significantly decreased the levels of the VEGF peptide secreted into conditioned media. This occurred in both HUVEC and human breast cancer cells and the effect was dose dependent. Furthermore, GTE and EGCG decreased the RNA levels of VEGF in MDA-MB231 cells. This inhibition occurred at the transcriptional regulation level and was accompanied by a significant decrease in VEGF promoter activity. We also showed that GTE decreased c-fos and c-jun RNA transcripts, suggesting that activator protein (AP)-1-responsive regions present in the human VEGF promoter may be involved in the inhibitory effect of GTE. Furthermore, GTE suppressed the expression of protein kinase C, another VEGF transcription modulator, in breast cancer cells. Inhibition of VEGF transcription appeared to be one of the molecular mechanism(s) involved in the antiangiogenic effects of green tea, which may contribute to its potential use for breast cancer treatment and/or prevention.

Inhibition of fibroblast growth factors by green tea.

Investigators have shown that green tea may decrease the risk of cancer. It is widely accepted that the main active component of green tea is EGCG (epigallocatechin-3-gallate). In our previous study, we examined the effect of green tea on breast cancer growth and endothelial cells both in in vitro assays and in animal models. Our data show that both mixed green tea extract (GTE) as well as its individual catechin components are effective in inhibiting breast cancer and endothelial cell proliferation in vitro, and that GTE suppresses breast cancer xenograft size and decreases the tumor blood vessel density in vivo. In the present study, we further demonstrate that 40 microg/ml GTE or EGCG can decrease the levels of the angiogenic factor bFGF (basic fibroblast growth factor) levels in the cells. This phenomenon is observed in both human umbilical vein endothelial cells (HUVECs) and in human breast cancer cells MDA-MB231. This effect is dose dependent. Furthermore, GTE and EGCG decrease the transcript levels of bFGF and aFGF (acidic fibroblast growth factor) in HUVECs and MDA-MB231 cells. Our findings suggest that the inhibition of the angiogenic fibroblast growth factors could account for one of the mechanisms of green tea's actions. Since cancer is angiogenesis dependent, this may partially explain the antineoplastic effects associated with green tea consumption.