Soy-derived isoflavones inhibit HeLa cell growth by inducing apoptosis

Flavonoids from the stems of Millettia pachyloba Drake mediate cytotoxic activity through apoptosis and autophagy in cancer cells

In this study, systematic separation and subsequent pharmacological activity studies were carried out to identify cytotoxic natural products from the dried stems of Millettia pachyloba Drake. Five previously undescribed isoflavones, pachyvones A-E; one previously undescribed xanthone, pachythone A; and twenty-two known compounds were obtained. The structures of these compounds were assigned on the basis of 1D/2D NMR data and high-resolution electrospray ionization mass spectroscopy analysis. Preliminary activity screening with HeLa and MCF-7 cells showed that ten compounds (3-5, 9, 12, 17-19, 24, and 25) had potential cytotoxicity. Further in-depth activity studies with five cancer cell lines (HeLa, HepG2, MCF-7, Hct116, and MDA-MB-231) and one normal cell line (HUVEC) revealed that these ten compounds showed specific cytotoxicity in cancer cells, with IC50 values ranging from 5 to 40 μM, while they had no effect on normal cell lines. To investigate whether the cytotoxicity of these ten compounds was associated with autophagy, their autophagic effects were evaluated in GFP-LC3-HeLa cells. The results demonstrated that compound 9 (durmillone) significantly induced autophagy in a concentration-dependent manner and had the best activity as an autophagy inducer among all of the compounds. Therefore, compound 9 was selected for further study. The PI/Annexin V double staining assay and Western blotting results revealed that compound 9 also induced obvious apoptosis in HeLa and MCF-7 cells, which suggests that it mediates cytotoxic activity through activation of both apoptosis and autophagy. Taken together, this study identified ten natural cytotoxic products from the dried stems of Millettia pachyloba Drake, of which compound 9 induced apoptosis and autophagy and could be an anticancer drug candidate.

Soy and tea intake on cervical cancer risk: the Singapore Chinese Health Study

PURPOSE

Soy isoflavones and tea catechins have immunomodulating and chemopreventive properties relevant for cervical carcinogenesis; however, there are limited epidemiologic data on the relationship of soy and tea consumption with cervical cancer risk. The aim of our study was to examine effects of soy and tea intake on cervical cancer risk among Singapore Chinese women.

METHODS

The association between intake of soy and tea drinking and cervical cancer risk was investigated in a prospective, population-based cohort of 30,744 Chinese women in Singapore with an average 16.7 years of follow-up and 312 incident cervical cancer cases. Multivariable proportional hazard models were used to estimate hazard ratio (HR) and 95% confidence interval (CI) of cervical cancer associated with intake levels of soy and tea.

RESULTS

High intake of soy alone was associated with a statistically borderline significant 20% reduced risk of cervical cancer (HR 0.80, 95% CI 0.61, 1.05) while green tea alone was not (HR 0.97, 95% CI: 0.76, 1.22). In stratified analysis, high intake of soy was associated with a statistically significant decrease in cervical cancer risk among green tea drinkers (HR 0.43; 95% CI 0.28, 0.69) but not among non-drinkers of green tea. The difference in the soy-cervical cancer risk association between green tea drinkers and non-drinkers was statistically significant (p for interaction = 0.004). This inverse association between soy intake and cervical cancer risk remained after further adjustment for human papillomavirus serostatus. Black tea consumption was not associated with cervical cancer risk.

CONCLUSIONS

These findings suggest that a protective effect of soy against cervical cancer development may depend on green tea constituents.

The Stimulatory Effect of Strontium Ions on Phytoestrogens Content in Glycine max (L.) Merr

The amount of secondary metabolites in plants can be enhanced or reduced by various external factors. In this study, the effect of strontium ions on the production of phytoestrogens in soybeans was investigated. The plants were treated with Hoagland's solution, modified with Sr(2+) with concentrations ranging from 0.5 to 3.0 mM, and were grown for 14 days in hydroponic cultivation. After harvest, soybean plants were separated into roots and shoots, dried, and pulverized. The plant material was extracted with methanol and hydrolyzed. Phytoestrogens were quantified by HPLC. The significant increase in the concentration of the compounds of interest was observed for all tested concentrations of strontium ions when compared to control. Sr(2+) at a concentration of 2 mM was the strongest elicitor, and the amount of phytoestrogens in plant increased ca. 2.70, 1.92, 3.77 and 2.88-fold, for daidzein, coumestrol, genistein and formononetin, respectively. Moreover, no cytotoxic effects were observed in HepG2 liver cell models after treatment with extracts from 2 mM Sr(2+)-stressed soybean plants when compared to extracts from non-stressed plants. Our results indicate that the addition of strontium ions to the culture media may be used to functionalize soybean plants with enhanced phytoestrogen content.

The flavonoid beverage Haelan 951 induces growth arrest and apoptosis in pancreatic carcinoma cell lines in vitro

BACKGROUND

A major challenge in pancreatic cancer treatment is the resistance of human pancreatic cancer cells to apoptosis. Soy isoflavones and calpain inhibition have been suggested to exert inhibitory effects on cancer development and progression. We investigated the effects of the isoflavone containing beverage Haelan 951 and the calpain inhibitor PD150606 on the viability, growth and apoptosis of the human pancreatic cancer cell lines CAPAN-1 and BxPC-3, on the rat pancreatic cancer cell line AR42J, and on human fibroblasts as the control cell line.

METHODS

Cellular viability and proliferation were determined using the LDH cytotoxicity and WST-1 assay, respectively. Apoptosis was detected by flow cytometric analyses of Annexin V-FITC labeled-cells, TUNEL assay and caspase activation. Student's t test or Mann-Whitney Rank Sum test were used to compare the data.

RESULTS

Haelan concentrations lower than 8% showed no cytotoxic effects, whereas higher concentrations led to necrosis. Eight percent Haelan induced significant growth inhibition of CAPAN-1 and BxPC-3 cell lines by 30% and 35%, respectively, compared with the control. The proliferation rate of AR42J cells decreased by 50%, whereas the fibroblasts remained unaffected. An 1.1-fold increase in apoptosis was found in CAPAN-1 cells, whereas the number of apoptotic BxPC-3 cells was elevated 2-fold. The number of apoptotic AR42J cells and fibroblasts was elevated 1.5-fold, each. Inhibition of calpain activity amplified the Haelan-induced growth inhibition of CAPAN-1 and BxPC-3 cells, but failed to amplify the growth inhibition of Haelan-treated AR42J cells. In fibroblasts, calpain inhibition induced Haelan-independent growth inhibition. Calpain inhibition also amplified the Haelan-induced apoptotic activity in all cancer cell lines, but exerted no further effect in fibroblasts.

CONCLUSIONS

The proliferation-inhibiting and apoptosis-inducing effects of Haelan are highly dependent on cell type and concentration administered. The results show for the first time that Haelan may be a promising candidate in the treatment of human pancreatic cancer, and its anticancer activity may be potentiated when administered with calpain inhibitors.

Isoflavone Attenuates the Caspase-1 and Caspase-3 Level in Cell Model of Parkinsonism

The study has investigated the effect of isoflavone attenuates the caspase-1 and caspase-3 level in cell model of Parkinsonism. The subjects were PC12 cells. They were randomly divided into six groups: control, MPP(+) (250 μmol/L), isoflavone (10 μM), isoflavone (10 μM) + MPP(+) (250 μmol/L), Z-YVAD-CHO (10 nM) + MPP(+) group, and Z-DEVD-CHO (10 nM) + MPP(+) group. Cell viability was measured by MTT methods; the content of tyrosine hydroxylase was measured by immunocytochemistry method of avidinbiotin peroxidase complex; apoptosis ratio was measured by flow cytometry. The results showed that cell viability in the MPP(+) group was lower than in all other five groups. There was no difference in cell viability between isoflavone + MPP(+) and control group. Optical density of TH positive cells in isoflavone group was higher than in control, isoflavone + MPP(+), and MPP(+) only groups. The apoptosis ratio in the isoflavone + MPP(+) group and control group and the Z-YVAD-CHO + MPP(+) and Z-DEVD-CHO + MPP(+) group was similar, which was lower than in the MPP(+) group. The lowest apoptosis ratio was found in the isoflavone only group.

Plants and cervical cancer: an overview

INTRODUCTION

Cervical cancer, the second most common gynecological malignant tumor seriously harmful to the health of women, remains a leading cause of cancer-related death for women in developing countries. Although a large amount of scientific research has been reported on plants as a natural source of treatment agents for cervical cancer, it is currently scattered across various publications. A systematic summary and knowledge of future prospects are necessary to facilitate further plant studies for anti-cervical cancer agents.

AREAS COVERED

This review generalizes and analyzes the current knowledge on the anti-cervical cancer properties and mechanisms involved for plants, and discusses the future prospects for the application of these plants.

EXPERT OPINION

This review mainly focuses on the plants which have been scientifically tested in vitro and/or in vivo and proved as potential agents for the treatment of cervical cancer. The failure of conventional chemotherapy to reduce mortality as well as serious side effects involved makes natural products ideal candidates for exerting synergism and attenuation effects on anticancer drugs. Although the chemical components and mechanisms of action of natural plants with anti-cervical cancer potential have been investigated, many others remain unknown. More investigations and clinical trials are necessary to make use of these medical plants reasonably.

The key involvement of estrogen receptor β and G-protein-coupled receptor 30 in the neuroprotective action of daidzein

Phytoestrogens have received considerable attention because they provide an array of beneficial effects, such as neuroprotection. To better understand the molecular and functional link between phytoestrogens and classical as well as membrane estrogen receptors (ERs), we investigated the effect of daidzein on the glutamate-mediated apoptotic pathway. Our study demonstrated that daidzein (0.1-10μM) inhibited the pro-apoptotic and neurotoxic effects caused by glutamate treatment. Hippocampal, neocortical and cerebellar tissues responded to the inhibitory action of daidzein on glutamate-activated caspase-3 and lactate dehydrogenase (LDH) release in a similar manner. Biochemical data were supported at the cellular level by Hoechst 33342 and calcein AM staining. The sensitivity of neuronal cells to daidzein-mediated protection was most prominent in hippocampal cultures at an early stage of development 7th day in vitro. A selective estrogen receptor β (ERβ) antagonist, 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5,-a]pyrimidin-3-yl]phenol (PHTPP), and a selective G-protein-coupled receptor 30 (GPR30) antagonist, 3aS(∗),4R(∗),9bR(∗))-4-(6-Bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-3H-cyclopenta[c]quinoline (G15), reversed the daidzein-mediated inhibition of glutamate-induced loss of membrane mitochondrial potential, caspase-3 activity, and LDH release. A selective ERα antagonist, methyl-piperidino-pyrazole (MPP), did not influence any anti-apoptotic effect of daidzein. However, a high-affinity estrogen receptor antagonist, 7α,17β-[9-[(4,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol (ICI) 182,780, and a selective GPR30 agonist, (±)-1-[(3aR(∗),4S(∗),9bS(∗))-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-8-yl]-ethanone (G1), intensified the protective action of daidzein against glutamate-induced loss of membrane mitochondrial potential and LDH release. In siRNA ERβ- and siRNA GPR30-transfected cells, daidzein did not inhibit the glutamate-induced effects. Twenty-four hour exposure to glutamate did not affect the cellular distribution of ERβ and GPR30, but caused greater than 100% increase in the levels of the receptors. Co-treatment with daidzein decreased the level of ERβ without significant changing of the GPR30 protein level. Here, we elucidated neuroprotective effects of daidzein at low micromolar concentrations and demonstrated that the phytoestrogens may exert their effects through novel extranuclear GPR30 and the classical transcriptionally acting ERβ. These studies uncover key roles of the ERβ and GPR30 intracellular signaling pathways in mediating the anti-apoptotic action of daidzein and may provide insight into new strategies to treat or prevent neural degeneration.

Concentration-dependent effects of the soy phytoestrogen genistein on the proteome of cultured cardiomyocytes

The soy-derived phytoestrogen genistein (GEN) has received attention for its potential benefits on the cardiovascular system by providing direct protection to cardiomyocytes against pathophysiological stresses. Here, we employed a proteomic approach to study the concentration-dependent effects of GEN treatments on cardiomyocytes. Cultured HL-1 cardiomyocytes were treated with low (1μM) and high (50μM) concentrations of GEN. Proteins were pre-fractionated by sequential hydrophilic/hydrophobic extraction and both protein fractions from each treatment group were separated by 2D gel electrophoresis (2DE). Overall, approximately 2,700 spots were visualized on the 2D gels. Thirty-nine and 99 spots changed in volume relative to controls (p<0.05) following the low- and high-concentration GEN treatments, respectively. From these spots, 25 and 62 protein species were identified by ESI-MS/MS and Mascot database searching, respectively. Identified proteins were further categorized according to their functions and possible links to cardioprotection were discussed. MetaCore gene ontology analysis suggested that 1μM GEN significantly impacted the anti-apoptosis process, and that both the low and high concentrations of GEN influenced the glucose catabolic process and regulation of ATPase activity. This proteomics study provides the first global insight into the molecular events triggered by GEN treatment in cardiomyocytes.