Genistein Induces Growth Inhibition and G2/M Arrest in Nasopharyngeal Carcinoma Cells

Nasopharyngeal carcinoma (NPC) is an endemic malignant disease of the head and neck region with unique features including striking ethnic and geographic variations as well as multifactorial etiology. Previous studies have demonstrated the anticancer properties of genistein, the major soy isoflavonoid, in several human cancer cells such as breast, prostate, colon, gastric, lung, and hepatoma. However, the action of genistein in NPC cells has not been determined. In this study, we investigated the inhibitory effects of genistein on NPC cells and its possible underlying mechanisms. We found that genistein dose-dependently inhibited the proliferation of human NPC cell line CNE2 cells. DNA flow cytometric analysis revealed that 30 to 120 μM genistein induced dramatic G2/M phase arrest in NPC cells. The mRNA expression levels, as shown by gene expression array and quantitative real-time polymerase chain reaction, and the protein expression levels of the cell cycle regulators p21^Cip1 and ATR (Ataxia telangiectasia and Rad3 related) were elevated following genistein treatment. Interestingly, we also observed concomitant induction of p15^Ink4b in genistein induced inhibitory effects in NPC cells. Moreover, selective estrogen receptor modulators did not affect genistein induced growth inhibition. These findings provide new insights into the potential intervention of NPC with genistein.     

Effects of Selenite and Genistein on G2/M Cell Cycle Arrest and Apoptosis in Human Prostate Cancer Cells

Combination of chemopreventive agents with distinct molecular mechanisms is considered to offer a potential for enhancing cancer prevention efficacy while minimizing toxicity. Here we report two chemopreventive agents, selenite and genistein, that have synergistic effects on apoptosis, cell cycle arrest, and associated signaling pathways in p53-expressing LNCaP and p53-null PC3 prostate cancer cells. We show that selenite induced apoptosis only, whereas genistein induced both apoptosis and G ₂ /M cell cycle arrest. Combination of these two agents exhibited enhanced effects, which were slightly greater in LNCaP than PC3 cells. Selenite or genistein alone upregulated protein levels of p53 in LNCaP cells only and p21 ^waf1 and Bax in both cell lines. Additionally, genistein inhibited AKT phosphorylation. Downregulation of AKT by siRNA caused apoptosis and G ₂ /M cell cycle arrest and masked the effects of genistein. Treatment with insulin-like growth factor I (IGF-I) elevated levels of total and phosphorylated AKT and suppressed the effects of genistein. Neither downregulation of AKT nor IGF-I treatment altered the cellular effects of selenite. Our study demonstrates that selenium and genistein act via different molecular mechanisms and exhibit enhanced anticancer effects, suggesting that a combination of selenium and genistein may offer better efficacy and reduction of toxicity in prostate cancer prevention.     

Caffeine Overcomes Genistein-Induced G2/M Cell Cycle Arrest in Breast Cancer Cells

Although inhibition of tumor cell growth by genistein is mediated by different types of cell cycle arrest, its regulation of genes related to the cell cycle is not clear. In this study, genistein caused a concentration-dependent growth inhibition in the hormone-independent cell line MDA-MB-435S. Flow cytometric analysis showed that genistein induced a concentration-dependent accumulation of cells in the G2/M phase of the cell cycle. Caffeine enhanced the inhibition of cell proliferation induced by genistein. Caffeine alone did not have an appreciable effect on the phases of the cell cycle, but caffeine at 3 mM completely eliminated genistein-induced G2/M cell cycle arrest. cDNA microarrays were used to investigate the mechanism of genistein-induced, caffeine-negated G2/M arrest. We identified 12 genes, which had opposite responses to genistein and caffeine treatments. Among these, 5 genes were upregulated by genistein and downregulated by caffeine; 7 genes were downregulated by genistein and upregulated by caffeine. Reversal by caffeine of genistein-induced G2/M phase arrest in breast cancer cell lines could increase their sensitivity to genistein and enhance genistein-induced inhibition of cell growth. Genes that have opposite responses to genistein and caffeine may be involved in regulation of the G2/M phase of the cell cycle.     

Equol Enhances Apoptosis-inducing Activity of Genistein by Increasing Bax/Bcl-xL Expression Ratio in MCF-7 Human Breast Cancer Cells

Anticancer activities of soy isoflavones, such as genistein and equol, a bioactive metabolite of daidzein, have been extensively studied because of possible involvement in the prevention of breast cancer. However, their interactions still remain unclear. We investigated here whether cytotoxic activity of genistein was enhanced by equol, using estrogen receptor positive MCF-7, HER2-positive SK-BR-3, and triple-negative MDA-MB-468 cell lines. Although cytotoxicity of genistein did not significantly differ between three subtypes of breast cancer cells, cytotoxic activities of genistein were significantly enhanced in combination with 50 μM equol in MCF-7 cells, but not in SK-BR-3 and MDA-MB-468 cells. In fluorescence activated cell sorting (FACS) analyses, MCF-7 cells were arrested at the G2/M by genistein but at G1/S by equol. Combination treatment arrested cells at G2/M but abolished equol-induced G1 block, indicating an antagonistic activity of genistein against equol in cell-cycle progression. Although apoptosis was not so evident with genistein alone, the combination made a drastic induction of apoptosis, accompanied by the increase of Bax/Bcl-xL expression ratio, without affecting the activities of Akt and mTOR. Taken together, these data suggest that enhancement of genistein activity by equol would be mainly mediated by augmented induction of apoptosis rather than arrest or delay of the cell cycle.     

Sodium Selenite Increases the Activity of the Tumor Suppressor Protein,PTEN, in DU-145 Prostate Cancer Cells

Epidemiological and clinical data suggest that selenium may prevent prostate cancer; however, the cellular effects of selenium in malignant prostate cells are not well understood. We previously reported that the activity of the tumor suppressor PTEN is modulated by thioredoxin (Trx) in a RedOx-dependent manner. In this study, we demonstrated that the activity of Trx reductase (TR) is increased by sevenfold in the human prostate cancer cell line, DU-145, after 5 days of sodium selenite (Se) treatment. The treatment of DU-145 cells with increasing concentrations of Se induced an increase in PTEN lipid phosphatase activity by twofold, which correlated with a decrease in phospho-ser ⁴⁷³ -Akt, and an increase in phospho-Ser ³⁷⁰ -PTEN levels. Se also increased casein kinase-2 (CK2) activity; and the use of apigenin, an inhibitor of CK2, revealed that the regulation of the tumor suppressor PTEN by Se may be achieved via both the Trx-TR system and the RedOx control of the kinase involved in the regulation of PTEN activity.     

Enterolactone Induces G1-phase Cell Cycle Arrest in Nonsmall Cell Lung Cancer Cells by Downregulating Cyclins and Cyclin-dependent Kinases

Flaxseed is a rich source of the plant lignan secoisolariciresinol diglucoside (SDG), which is metabolized into mammalian lignans enterodiol (ED) and enterolactone (EL) in the digestive tract. The anticancer properties of these lignans have been demonstrated for various cancer types, but have not been studied for lung cancer. In this study, we investigated the anticancer effects of EL for several nonsmall cell lung cancer (NSCLC) cell lines of various genetic backgrounds. EL inhibited the growth of A549, H441, and H520 lung cancer cells in concentration- and time-dependent manners. The antiproliferative effects of EL for lung cancer cells were not due to enhanced cell death, but rather due to G₁-phase cell cycle arrest. Molecular studies revealed that EL decreased mRNA or protein expression levels of the G₁-phase promoters cyclin D1, cyclin E, cyclin-dependent kinases (CDK)-2, -4, and -6, and p-cdc25A; decreased phosphorylated retinoblastoma (p-pRb) protein levels; and simultaneously increased levels of p21^WAF1/CIP1, a negative regulator of the G₁ phase. The results suggest that EL inhibits the growth of NSCLC cell lines by downregulating G₁-phase cyclins and CDKs, and upregulating p21^WAF1/CIP1, which leads to G₁-phase cell cycle arrest. Therefore, EL may hold promise as an adjuvant treatment for lung cancer therapy.     

Hesperidin Induces ROS-Mediated Apoptosis along with Cell Cycle Arrest at G2/M Phase in Human Gall Bladder Carcinoma

A natural predominant flavonoid hesperidin rich in citrus fruits exhibits multifunctional medicinal properties. The anticancerous potential of hesperidin has been widely explored; however, the gall bladder carcinoma (GBC) still remains untouched due to the unavailability of efficient experimental model. The aim of our study was to identify the apoptotic and antiproliferative potential of hesperidin in GBC. The promising efficacy of hesperidin was assessed through the generation of reactive oxygen species (ROS), cellular apoptosis, and loss of mitochondrial membrane potential (MMP) in the primary cells generated from surgically removed cancerous gall bladder tissues. Moreover, cell cycle analysis and caspases-3 activity were performed to confirm the apoptosis inducing potential of hesperidin. Results revealed that hesperidin exposure for 24?h at a dose of 200?µM reduced the cell proliferation of GBC cells significantly. In addition, hesperidin treatment further resulted in an increased ROS generation and nuclear condensation at the same dose. Caspase-3 activation and cell cycle arrest at G2/M phase were also accelerated in a dose-dependent manner. Together, these results suggest that hesperidin can be considered as a potential anticancerous compound for the treatment of GBC. Furthermore, evaluation of the pharmacological aspects of hesperidin is desirable for drug development.     

蓖麻毒素引起HeLa细胞凋亡和细胞周期G2／M期阻滞

目的蓖麻毒素与HeLa细胞共培养,观察蓖麻毒素引起细胞毒性死亡规律及对细胞周期的影响.方法噻唑蓝(MTT)比色法测定细胞毒性,流式细胞分析仪分析细胞周期.结果10-3μmol@L-1蓖麻毒素即可引起HeLa细胞死亡,随着蓖麻毒素浓度的升高,其细胞毒性增大,10μmol@L-1蓖麻毒素与细胞作用24h,其细胞存活率为39.6%.0.05μmol@L-1蓖麻毒素可引起HeLa细胞发生典型的细胞凋亡,主要表现为细胞核染色质浓缩,碎裂,形成新月状核或膜包裹核染色质的凋亡小体.结论0.05μmol@L-1蓖麻毒素对细胞周期G0/G1期无影响,但对G2/M有影响.作用24h,G2/M期细胞从对照组的13.86±0.48%上升至33.15±0.45%,细胞周期阻滞在G2/M期.     

Koelreuteria Formosana Extract Induces Growth Inhibition and Cell Death in Human Colon Carcinoma Cells via G2/M Arrest and LC3-II Activation-Dependent Autophagy

Autophagy is a self-destructive process that degrades cytoplasmic constituents. In our previous study, Koelreuteria formosana ethanolic extract (KFEE), which is obtained from natural plants endemic to Taiwan, has inhibited cell metastasis in renal carcinoma cells. However, the anticancer effects of KFEE on colon cancer remain unclear. In this study, KFEE exerted a strong cytotoxic effect on DLD-1 and COLO 205 human colorectal cancer cell lines. KFEE effectively inhibited cancer cell proliferation, induced G2/M-phase arrest associated with downregulaton of cyclin E, cyclin B and cdc25C and upregulation of p21, and induced cell death by activating autophagy but did not cause apoptotic cell death. Exposed KFEE cells showed increased levels of acridine orange, autophagic vacuoles, and LC3-II proteins, which are specific autophagic markers. Bcl-2, p-Akt, and p-mTOR levels, which have been implicated in autophagic downregulation, were decreased after KFEE treatment. Autophagy inhibitor 3-methyladenosine and bafilomycin-A1 and genetic silencing of LC3 attenuated KFEE-induced growth inhibition. These findings suggested that KFEE causes cytostatic effect through autophagy. In xenograft studies, oral administration of KFEE had significantly inhibited the tumor growth in nude mice that had received subcutaneous injection of DLD-1 cells. KFEE is a promising candidate in phytochemical-based, mechanistic, and pathway-targeted cancer prevention strategies.     

Carvacrol Induces Reactive Oxygen Species (ROS)-mediated Apoptosis Along with Cell Cycle Arrest at G0/G1 in Human Prostate Cancer Cells

Carvacrol, a major monoterpenoid phenol from Origanum and Thymus species, has been shown to exhibit antiproliferative and anticancer properties in a few recent studies. Nevertheless, detailed mechanism of the action of this compound in prostate cancer has not been elucidated yet. Therefore, in the current study, we examined the anticancer activity and mechanism of the action of carvacrol against human prostate cancer cells. It was found that the treatment of DU145 cells with carvacrol decreased cell viability in a concentration and time-dependent manner. The antiproliferative action of carvacrol leads to induction of apoptosis as confirmed by nuclear condensation, Annexin V-FITC/PI positive cells, and caspase-3 activation. In addition, carvacrol augmented reactive oxygen species generation and disruption in the mitochondrial membrane potential which has not been reported in the previous studies of carvacrol with prostate cancer. Moreover, carvacrol-induced apoptosis of prostate cancer cells was also accompanied by significant amount of growth arrest at the G₀/G₁ phase of the cell cycle which has also not been documented previously. To sum up, this study has established that carvacrol could be a promising chemotherapeutic agent and could have a direct practical implication and translational relevance to prostate cancer patients as Origanum consumption may retard prostate cancer progression.     

胆管癌中抑癌基因PTEN的表达及其与P53表达相关性的研究

目的研究PTEN和P53蛋白在胆管癌中的表达情况、相互关系及其临床病理学意义。方法应用免疫组化SP法对36例胆管癌标本，8例正常胆管组织和30例胆管癌旁组织中PTEN及P53蛋白表达情况进行研究。结果胆管癌中PTEN蛋白的阳性表达率为63.89％（23/36），明显低于正常胆管组织（100％，8/8）和癌旁组织（100％，30/30）；其表达与胆管癌的分化程度及有无转移有关而与部位无关。P53蛋白在胆管癌中的阳性表达率为44.44％（16/36），明显高于正常胆管组织（0％，0/8）和癌旁组织（0％，0/30）；其表达与胆管癌的分化程度有关而与部位及有无转移无关。胆管癌中PTEN与P53蛋白表达具有相关性。结论PTEN蛋白在胆管癌中表达下降，并且其表达与胆管癌的分化程度及有无转移有关而与肿瘤部位无关。P53蛋白在胆管癌中表达升高，其表达与胆管癌的分化程度有关而与肿瘤部位及有无转移无关。胆管癌中PTEN与P53蛋白表达具有相关性。     

2-Deoxyglucose Induces Cell Cycle Arrest and Apoptosisin Colorectal Cancer Cells Independent of Its Glycolysis Inhibition

2-Deoxyglucose (2DG) is an anticancer drug with excellent safety profile. Because of its higher dose requirements, its potential is yet to translate into a monotherapy. However, recently, 2DG has been tested as an adjunct in established chemotherapeutic regimens. 2DG enhanced the potency of several chemotherapeutic agents but not all. The rationale selection of known chemotherapeutic agents to use with 2DG is hampered becaue of the lack of complete understanding of mechanism behind 2DG anticancer effects. Although, 2DG is a well-known glycolytic inhibitor, which inhibits the key glycolytic enzyme hexokinase, its anticancer effects cannot be fully explained by this simplistic mechanism alone. In this article, we have shown for the first time that 2DG induced a transient expression of p21 and a continuous expression of p53 in colorectal cancer cells (SW620). The treatment also caused cell cycle arrest at G0/G1 phase and induced apoptosis through the mitochondrial pathway. The effects of 2DG on p21 and p53 protein levels were totally independent of its inhibitory effect on either hexokinase or ATP levels. Results from this study provides key insights into novel molecular mechanisms of 2DG and directs rational selection of other anticancer drugs to combine with 2DG in colorectal cancer treatment.     

Bovine Lactoferrin Induces Cell Cycle Arrest and Inhibits Mtor Signaling in Breast Cancer Cells

Lactoferrin (LF) is predominantly found in mammalian secretions with recognized anticancer potential, although the mechanisms involved in such activity are still unclear. Here, the stability, internalization, and cytotoxicity of bovine LF (bLF) and its variants were tested against a panel of breast cancer cells. bLF was found to be very stable under incubation with cells and also able to internalize them, although most of the protein remained in the culture medium. Furthermore, bLF (up to 30 μM) inhibited the growth of breast cancer cells (T-47D, MDA-MB-231, Hs578T, and MCF-7) in a higher extent than in the normal counterpart cell line (MCF-10-2A), thus suggesting its selectivity. Regarding its variants, only the iron-saturated protein showed a higher activity compared with the commercial bLF. bLF growth inhibitory activity was associated with the induction of cell cycle arrest, but not with apoptosis. Moreover, exposure to bLF increased the cells phospho-AMPKα levels and decreased both phospho threonine mammalian target of rapamycin (mTOR) and total mTOR levels, indicating a novel mechanism of action through its ability to induce nutrient/energy-related stress. This study disclosed important findings to better understand the mechanisms underlying the bLF effects on breast cancer cell lines, which could be valuable for novel advances in the cancer research field.     

Cochinchina Momordica Seed Extract Induces Apoptosis and Cell Cycle Arrest in Human Gastric Cancer Cells Via PARP and p53 Signal Pathways

Cochinchina momordica seed is the dried ripe seed of Momordica cochinchinensis (Lour.) Spreng, which is a kind of fruit and consumed for dietary as well as medicinal uses. In this study, using the human SGC7901 and MKN-28 gastric cancer cell lines, we explored the anticancer activity of the extract from cochinchina momordica seed (ECMS). ECMS inhibited significantly the survival rates of SGC7901 and MKN-28 cells in concentration- and time-dependent manners by MTT assay. The typical apoptotic morphological changes were observed by Hoechst 33258 dye assay after SGC7901 and MKN-28 cells were treated with ECMS for 48 h. Flow cytometry analysis revealed that ECMS-treatment blocked the cells at the S phase of cell cycle. Furthermore, the protein expression levels of poly (ADP-ribose) polymerase (PARP) and Bcl-2 were downregulated notably by ECMS-treatment, whereas those of Fas/Fas-associated death domain, p53, and Bax were upregulated in SGC7901 cells. ECMS dramatically enhanced the enzymatic activities of caspase-3 and caspase-9 whilst slightly increased caspase-8 activity. Taken together, this study demonstrated that ECMS exerted cytotoxic activities via PARP and p53 signal pathways in the human gastric cancer cells.     

胃癌淋巴结转移灶中PTEN与COX-2的表达及意义

目的分析PTEN与COX-2在胃癌淋巴结转移灶中的表达及意义,为今后的临床诊疗工作提供有价值的参考依据。方法收集2017年11月—2018年12月间收治的经手术病理证实为胃腺癌的患者81例作为研究对象,将患者按照是否发生淋巴结转移分成转移组(46例)与非转移组(35例),采用免疫组化S-P法对两组患者胃癌组织以及胃癌淋巴结转移灶中PTEN、COX-2水平进行检测,并对检测结果进行统计分析。结果转移灶与胃癌组织标本中COX-2的表达阳性率存在统计学差异,前者高于后者(P <0. 05);转移灶与胃癌组织标本中PTEN的表达阳性率存在统计学差异,前者低于后者(P <0. 05)。结论 COX-2、PTEN之间可能存在相互作用,并且在胃癌淋巴结转移中均发生了重要作用,临床价值显著,值得关注并推广。     

Gamma Tocopherol Upregulates the Expression of 15-S-HETE and Induces Growth Arrest Through a PPAR Gamma-Dependent Mechanism in PC-3 Human Prostate Cancer Cells

Chronic inflammation and dietary fat consumption correlates with an increase in prostate cancer. Our previous studies in the colon have demonstrated that γ-tocopherol treatment could upregulate the expression of peroxisome proliferator-activated preceptors (PPAR) γ, a nuclear receptor involved in fatty acid metabolism as well modulation of cell proliferation and differentiation. In this study, we explored the possibility that γ-tocopherol could induce growth arrest in PC-3 prostate cancer cells through the regulation of fatty acid metabolism. Growth arrest (40%) and PPAR γ mRNA and protein upregulation was achieved with γ-tocopherol within 6 h. γ-Tocopherol-mediated growth arrest was demonstrated to be PPAR γ dependent using the agonist GW9662 and a PPAR γ dominant negative vector. γ-tocopherol was shown not to be a direct PPAR γ ligand, but rather 15-S-HETE (an endogenous PPAR γ ligand) was upregulated by γ-tocopherol treatment. 15-Lipoxygenase-2, a tumor suppressor and the enzyme that converts arachidonic acid to 15-S-HETE, was upregulated at 3 h following γ-tocopherol treatment. Expression of proteins downstream of the PPAR γ pathway were examined. Cyclin D1, cyclin D3, bcl-2, and NFκ B proteins were found to be downregulated following γ-tocopherol treatment. These data demonstrate that the growth arrest mediated by γ-tocopherol follows a PPAR-γ-dependent mechanism.     

Hydroxytyrosol Induces Apoptosis and Cell Cycle Arrest and Suppresses Multiple Oncogenic Signaling Pathways in Prostate Cancer Cells

Scope: Hydroxytyrosol (HT), a polyphenol from olives, is a potential anticancer agent. This study was designed to evaluate the anticancer activity of HT against prostate cancer cells, and the mechanism thereof. Methods and Results: Treatment of LNCaP and C4-2 prostate cancer cells with HT resulted in a dose-dependent inhibition of proliferation. This was in contrast to HT's ineffectiveness against normal prostate epithelial cells RWPE1 and PWLE2, suggesting cancer-cell-specific effect. HT induced G1/S cell cycle arrest, with inhibition of cyclins D1/E and cdk2/4 and induction of inhibitory p21/p27. HT also induced apoptosis, as confirmed by flow cytometry, caspase activation, PARP cleavage, and BAX/Bcl-2 ratio. It inhibited the phosphorylation of Akt/STAT3, and induced cytoplasmic retention of NF-κB, which may explain its observed effects. Finally, HT inhibited androgen receptor (AR) expression and the secretion of AR-responsive prostate-specific antigen. Conclusion: Castration-resistant prostate cancers retain AR signaling and are often marked by activated Akt, NF-κB, and STAT3 signaling. Our results establish a pleiotropic activity of HT against these oncogenic signaling pathways. Combined with its nontoxic effects against normal cells, our results support further testing of HT for prostate cancer therapy.     

Dimethyl Sulfoxide Extract of Dianthus carmelitarum Induces S Phase Arrest and Apoptosis in Human Colon Cancer Cells

Although several studies have investigated the cytotoxic effects of different Dianthus species, there has been only limited research into the cytotoxic effect of Dianthus carmelitarum. The purpose of this research was to evaluate the phenolic characterization and the cytotoxic effect of D. carmelitarum on human colon cancer (WiDr) cells and the possible mechanisms involved. Total polyphenolic contents (TPC) and phenolic characterization of the extract were evaluated using the Folin-Cioceltau method and reversed-phase high performance liquid chromatography (RP-HPLC), respectively. The cytotoxic activity of the extract was determined using the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. The mechanism involved in the extract’s cytotoxic effect was then evaluated in terms of apoptosis and the cell cycle using flow cytometry, while mitochondrial membrane potential (MMP) was investigated using the fluorometric method. The TPC value of the extract was 784.8?±?40.3?mg gallic acid equivalent per 100?g sample, and sinapic acid and benzoic acid were detected as major phenolics in the extract. D. carmelitarum extract exhibited a selective cytotoxic effect (3.6-fold) on WiDr cells compared to normal colon cells. The extract induced cell cycle arrest at the S phase and apoptosis via reduced MMP in WiDr cells. Phytomedical and nutraceutical applications of D. carmelitarum may represent promising approaches in the treatment of cancer.     

Effects of Estrogen Metabolite 2-Methoxyestradiol on Tumor Suppressor Protein p53 and Proliferation of Breast Cancer Cells

An endogenous 17β-estradiol (E₂) metabolite, 2-methoxyestradiol (2-ME₂), has been reported to exhibit estrogen receptor (ER)-independent anti-angiogenic and anti-tumor effects. Several mechanisms have been proposed for 2-ME₂ actions, but there is a lack of evidence for a common pathway for all of the cell-types sensitive to this metabolite. We have examined potential alterations in p53 in response to 2-ME₂, E₂ and the microtubule disruptor taxol in T47D breast cancer cells. Cells were cultured for six days in medium depleted of endogenous steroids or effectors. Semi-confluent cells were treated with 2-ME₂ (1?nM – 10?µM), 10?nM E₂ and/or 1?µM taxol and subjected to SDS-PAGE and Western blot analysis, quantitative analysis, or laser-scanning confocal microscopy. Western blot analysis revealed a concentration-dependent biphasic trend in p53 levels. Addition of 10?nM – 1?µM 2-ME₂ induced significant up-regulation in p53, and this response gradually diminished to levels comparable to the control upon treatment with higher concentrations (2.5 – 10 µM). The observed upregulation of p53 induced by 2-ME₂ is inhibited by concurrent treatment with 1?µM taxol. Cell quantitation revealed a significant decrease (50 – 90%) in cell number upon treatment with 1 – 10?µM 2-ME₂ with minimal effect at lower concentrations. No additional effect on cell proliferation was observed when taxol was combined with 10?nM or 1?µM 2-ME₂. In a concentration dependent manner, treatment with 2-ME₂ for 24?h differentially influenced cellular localization of p53. These results may aid in further understanding the relationship between steroid receptors, tumor suppressor proteins, and effects of hormone metabolites on breast cancer cells.     

Origanum Vulgare Induces Apoptosis in Human Colon Cancer Caco2 Cells

Oregano spice is widely used in the Mediterranean diet, which is associated with a low risk for colon cancer. Although the medicinal benefits of oregano, such as the anti-inflammatory and antimicrobial activities, are well known; nonetheless, only few data are available on its effect in cancer prevention, especially concerning the mechanism of action. Here, we investigated the effect of Origanum vulgare ethanolic extracts on redox balance, cell proliferation, and cell death in colon adenocarcinoma Caco2 cells. Oregano extract leads to growth arrest and cell death in a dose- and time-dependent manner. Changes in glutathione content, as well as the increase in its oxidized form, may be involved in oregano-triggered death. Both extrinsic and intrinsic apoptotic pathways appear to be activated by spice extract. Our findings suggest that oregano amounts found in the Mediterranean diet can exert proapoptotic effects, which are selective for cancer cells. Moreover, whole extract, instead of a specific component, can be responsible for the observed cytotoxic effects.