Growth inhibitory effect of green tea extract in Ehrlich ascites tumor cells involves cytochrome c release and caspase activation

Phytochemistry and polypharmacology of cleome species: A comprehensive Ethnopharmacological review of the medicinal plants

ETHNOPHARMACOLOGICAL RELEVANCE

Cleome species in particular (C. gynandra Linn, C. viscosa Linn, C. rutidosperma DC, C. felina Linn.), commonly known as spider flowers, belong to the genus of flowering plants in Cleomaceae family. Found primarily in the African countries (Kenya, Tanzania, Egypt, South Africa, and Nigeria), Asian countries (India and Afghanistan), European countries (Italy), and also in other countries like Brazil and Austria. These plants are commonly cultivated as a vegetable crop for their nutritional benefits, and the leaves are widely consumed for their health-promoting effects. The different parts of the plants, such as leaves, seeds, flowers, and roots, are used to treat acute and chronic inflammatory disorders, hepatotoxicity, malaria, fungal diseases, and cancer.

AIM OF THE STUDY

Detailed investigations in underlining the molecular mechanisms and their wide variety of effects in treating various diseases remain ambiguous. The review focuses on an in-depth discussion of studies targeting phytochemistry and polypharmacology. Thus, the review aims to recapitulate the therapeutic potential of the components of Cleome involved in the treatment of a wide variety of ailments from ancient times were collected and presented along with strategies aiming for future studies.

MATERIALS AND METHODS

The information provided is collected from several scientific databases (PubMed, Elsevier, ScienceDirect) and traditional medicine books, and other professional websites.

RESULTS AND CONCLUSION

Investigations and current evidence revealed that the different chemical constituents present in cleome species possess various health-promoting effects along with the aerial parts showing promising traditional uses in traditional healing and culinary. An explorative survey in the current review highlights the traditional healing effects along with a broad scope of studies that can be performed in the future.

Inhibitory potential of Hydroxychavicol on Ehrlich ascites carcinoma model and in silico interaction on cancer targets

Hydroxychavicol (HC), a major phenolic derivative isolated from the leaves of Piper betle L. is well known for its antibacterial, antifungal and antimutagenic properties. The present study evaluated the in vivo antitumor activity of HC against Ehrlich Ascites Carcinoma (EAC) cells in Swiss albino mice and in silico interaction of HC with the receptors involved in the cancer. Hydroxychavicol (200 and 400 mg/kg bw) was orally administered for 21 consecutive days and was effective in inhibiting the tumor growth in ascitic mouse model. HC consistently reduced the tumor volume, viable cell count, lipid peroxidation and elevated the life span of HC treated mice. Besides the hematological profiles, SGOT and SGPT levels reverted back to normal and oxidative stress markers GSH, SOD and CAT also increased in HC treated groups. In silico docking analysis revealed that HC possessed potent antagonist activity against all the cancer targets demonstrating its inhibitory activity.

GROWTH FACTORS AND COX2 IN WOUND HEALING: AN EXPERIMENTAL STUDY WITH EHRLICH TUMORS

Background

Healing is an innate biological phenomenon, and carcinogenesis acquired, but with common humoral and cellular elements. Carcinogenesis interferes negatively in healing.

Aim

To evaluate the histological changes in laparotomy scars of healthy Balb/c mice and with an Ehrlich tumor in its various forms of presentation.

Methods

Fifty-four mice were divided into three groups of 18 animals. First group was the control; the second had Ehrlich tumor with ascites; and the third had the subcutaneous form of this tumor. Seven days after tumor inoculation, all 54 mice were submitted to laparotomy. All of the animals in the experiment were operated on again on 7th day after surgery, with resection of the scar and subsequent euthanasia of the animal. The scars were sent for histological assessment using immunohistochemical techniques to evaluate Cox-2 (cyclooxygenase 2), VEGF (vascular endothelial growth factor) and FGF (fibroblast growth factor). Semi-quantitatively analysis was done in the laparotomy scars and in the abdominal walls far away from the site of the operation.

Results

Assessing the weight of the animals, the correct inoculation of the tumor and weight gain in the group with tumoral ascites was observed. The histological studies showed that groups with the tumor showed a statistically significant higher presence of Cox-2 compared to the control. In the Cox-2 analysis of the abdominal wall, the ascites group showed the most significant difference. VEGF did not present any significant differences between the three groups, regardless of the site. The FGF showed a significant increase in animals with the tumor.

Conclusion

Histological findings in both laparotomy scar and the abdominal wall showed that with Ehrlich's neoplasia there was an exacerbated inflammatory response, translated by more intense expression of Cox-2 and greater fibroblast proliferation, translated by more intense expression of FGF, that is, it stimulated both the immediate inflammatory reactions, observed with Cox-2 reactions, and late scarring by fibroblasts and FGF.

Incomplete Killing And Enhanced Activation of Islet-Reactive CD8+ T Cells by FasL-Expressing Dendritic Cells Limits Protection from Diabetes

AIMS

Autologous dendritic cells (DC) are a promising tool for induction of cytotoxic CD8+ T cell immunity against tumors and chronic viral infections. When armed with the death-inducing Fas-ligand (FasL, CD195), DC attenuate delayed-type hypersensitivity reactions and allotransplant rejection by promoting activation-induced cell death in T cells. We investigated the possibility of using FasL-expressing DC to induce deletion of islet-reactive CD8+ T cells in vivo, and to prevent destruction of pancreatic islets in a model of autoimmune diabetes.

METHODS

DC, propagated from mouse bone marrow cells, were purified and made to express FasL and islet-antigen via plasmid transfection. CD8+ T cells (OT-I cells) recognizing the antigen, ovalbumin, were adoptively transferred to transgenic mice expressing ovalbumin in islets (RIP-OVA(lo) mice), and these mice were primed with ovalbumin. To test the potential of DC to prevent diabetes in this model, the mice were later intravenously vaccinated with the transfected DC.

RESULTS

Transfected DC induced partial deletion of antigen-reactive CD8+ T cells in vivo and reduced the level of lymphocyte infiltration into pancreatic islets. Diabetes developed less frequently in vaccinated mice, but this effect was limited. Further in vitro analysis showed that FasL-expressing DC not only deleted many of the responding CD8+ T cells but also promoted the expansion of surviving cells and their IFN-gamma production.

CONCLUSIONS

FasL-expressing DC can also have stimulatory effects on CD8+ T cells warranting further investigation into the optimal design of tolerance-promoting DC-vaccination to prevent autoimmune diabetes.

Epigallocatechin activates haem oxygenase-1 expression via protein kinase Cdelta and Nrf2

The Nrf2/anti-oxidant response element (ARE) pathway plays an important role in regulating cellular anti-oxidants, including haem oxygenase-1 (HO-1). Various kinases have been implicated in the pathways leading to Nrf2 activation. Here, we investigated the effect of epigallocatechin (EGC) on ARE-mediated gene expression in human monocytic cells. EGC time and dose dependently increased HO-1 mRNA and protein expression but had minimal effect on expression of other ARE-regulated genes, including NAD(P)H:quinone oxidoreductase 1, glutathione cysteine ligase and ferritin. siRNA knock down of Nrf2 significantly inhibited EGC-induced HO-1 expression. Furthermore, inhibition of PKC by Ro-31-8220 dose dependently decreased EGC-induced HO-1 mRNA expression, whereas MAP kinase and phosphatidylinositol-3-kinase pathway inhibitors had no significant effect. EGC stimulated phosphorylation of PKCalphabeta and delta in THP-1 cells. PKCdelta inhibition significantly decreased EGC-induced HO-1 mRNA expression, whereas PKCalpha- and beta-specific inhibitors had no significant effect. These results demonstrate for the first time that EGC-induced HO-1 expression occurs via PKCdelta and Nrf2.

Bcl-2 antisense oligonucleotide inhibits the proliferation of childhood leukemia/lymphoma cells of the B-cell lineage

An 18-mer phosphorothioate bcl-2 antisense oligonucleotide (ASO) inhibited colony formation of three B-cell leukemia/lymphoma cell lines in a dose dependent manner in the range of 0.125-0.5 micromol/l. The scrambled cogener had no detectable effect. A decrease in BCL-2 protein and apoptotic DNA fragmentation was detected in the studied cell lines and primary blast cells of two children with acute lymphoblastic leukemia. Neither BCL-2 protein level, nor DNA integrity was affected by the scrambled control indicating the specific effect ASO. As far as we know, this is the first report on the effects of bcl-2 ASO on childhood leukemia/lymphoma cell samples.

Induction of apoptosis by epigallocatechin-3-gallate in human lymphoblastoid B cells

(-)-Epigallocatechin-3-gallate (EGCG), a major constituent of green tea polyphenols, has been shown to suppress cancer cell proliferation and induce apoptosis. In this study we investigated its efficacy and the mechanism underlying its effect using human B lymphoblastoid cell line Ramos, and effect of co-treatment with EGCG and a chemotherapeutic agent on apoptotic cell death. EGCG induced dose- and time-dependent apoptotic cell death accompanied by loss of mitochondrial transmembrane potential, release of cytochrome c into the cytosol, and cleavage of pro-caspase-9 to its active form. EGCG also enhanced production of intracellular reactive oxygen species (ROS). Pretreatment with diphenylene iodonium chloride, an inhibitor of NAD(P)H oxidase and an antioxidant, partially suppressed both EGCG-induced apoptosis and production of ROS, implying that oxidative stress is involved in the apoptotic response. Furthermore, we showed that combined-treatment with EGCG and a chemotherapeutic agent, etoposide, synergistically induced apoptosis in Ramos cells.

Cellular thiol status-dependent inhibition of tumor cell growth via modulation of p27kip1 translocation and retinoblastoma protein phosphorylation by 1′-acetoxychavicol acetate

1'-Acetoxychavicol acetate (ACA) has been shown to inhibit tumor cell growth, but there is limited information on its effects on cell signaling and the cell cycle control pathway. In this study, we sought to determine how ACA alters cell cycle and its related control factors in its growth inhibitory effect in Ehrlich ascites tumor cells (EATC). ACA caused an accumulation of cells in the G1 phase and an inhibition of DNA synthesis, which were reversed by supplementation with N-acetylcysteine (NAC) or glutathione ethyl ester (GEE). Furthermore, ACA decreased hyperphosphorylated Rb levels and increased hypophosphorylated Rb levels. NAC and GEE also abolished the decease in Rb phosphorylation by ACA. As Rb phosphorylation is regulated by G1 cyclin dependent kinase and CDK inhibitor p27(kip1), which is an important regulator of the mammalian cell cycle, we estimated the amount of p27(kip1) levels by western blotting. Treatment with ACA had virtually no effect on the amount of p27(kip1) levels, but caused a decrease in phosphorylated p27(kip1) and an increase in unphosphorylated p27(kip1) as well as an increase in the nuclear localization of p27(kip1). These events were abolished in the presence of NAC or GEE. These results suggest that in EATC, cell growth inhibition elicited by ACA involves decreases in Rb and p27(kip1) phosphorylation and an increase in nuclear localization of p27(kip1), and these events are dependent on the cellular thiol status.

Deoxy-adenosine-monophosphate (dAMP) di-n-butylester induces apoptosis by increasing the dATP level in HL-60 cells

Deoxy-ATP is a potent inducer of apoptosis. We intended to synthesize a lipophilic dAMP derivative which, according to our working hypothesis penetrates into the cell, is converted to dAMP by intracellular esterases and to dATP by nucleotide kinases. We synthesized dAMP-di-n-butylester (DAB) and tested it. We found that it fulfills the above-described expectations. DAB treatment decreases the viability of HL-60 cells, increases the dATP concentration and induces apoptogenic cytochrome c release from mitochondria with concomitant elevation of caspase-9 activity. Our results indicate that use of dAMP derivatives with masked phosphate may be a feasible approach for pharmacological elevation of intracellular dATP and induction of apoptosis.

Anticancer effects of (-)-epigallocatechin-3-gallate on ovarian carcinoma cell lines

PURPOSE

A constituent of green tea, (-)-epigallocatechin-3-gallate (EGCG), has been known to possess anti-cancer properties. In this study, we investigated the time-course anticancer effects of EGCG on human ovarian cancer cells to provide insights into the molecular-level understanding of growth suppression mechanism involved in EGCG-mediated apoptosis and cell cycle arrest.

METHODS

Three human ovarian cancer cell lines (p53 negative, SKOV-3 cells; mutant type p53, OVCAR-3 cells; and wild type p53, PA-1 cells) were used. The effect of EGCG treatment was studied via cell count assay, cell cycle analysis, FACS, Western blot, and macroarray assay.

RESULTS

EGCG exerts a significant role in suppressing ovarian cancer cell growth. Also, EGCG showed growth inhibitory effects in each cell line in a dose-dependent fashion and induced apoptosis and cell cycle arrest. The cell cycle was arrested at the G(1) phase by EGCG in SKOV-3 and OVCAR-3 cells. In contrast, the cell cycle was arrested in the G(1)/S phase arrest in PA-1 cells. EGCG differentially regulated the expression of genes and proteins (Bax, p21, Retinoblastoma, cyclin D1, CDK4, Bcl-X(L)) more than 2-fold, showing a possible gene regulatory role of EGCG. The continual expression in p21WAF1 suggests that EGCG acts in the same way with p53 proteins to facilitate apoptosis after EGCG treatment. And Bax, PCNA, and Bcl-X are important in EGCG-mediated apoptosis. In contrast, CDK4 and Rb are not important in ovarian cancer cell growth inhibition.

CONCLUSION

EGCG can inhibit ovarian cancer cell growth through induction of apoptosis and cell cycle arrest as well as regulation of cell cycle-related proteins. Thereby, the EGCG-mediated apoptosis can be applied to an advanced strategy in the development of a potential drug against ovarian cancer.

Effect of green tea extract on the induction of ornithine decarboxylase and the activation of extracellular signal-regulated kinase in bladder carcinoma ECV304 cells

According to several studies, green tea and individual catechins can inhibit the induction of ornithine decarboxylase (ODC), the key enzyme in the biosynthesis of polyamines. It has been suggested that the inhibition of ODC induction may offer an explanation to the anticancer and chemopreventive activities of green tea. In the present study, however, treatment of bladder carcinoma ECV304 cells with green tea extract (GTE) was not able to reduce the induction of ODC by fetal calf serum. Actually, in the absence of serum, GTE provoked a dose-dependent and remarkable induction of ODC activity. The induction of ODC, which could be elicited also by (-)-epigallocatechin 3-gallate, a major green tea component, required an early activation of extracellular signal-regulated kinase 1 and 2 (ERK), and both events appeared to be dependent on an alteration of the status of cellular thiol groups. Pretreatment with specific ERK or ODC inhibitors was able to prevent a late caspase activation but hardly affected the loss of cell viability provoked by GTE. In conclusion, to our knowledge, this is the first study showing that GTE can promote ODC induction in a tumor cell line.

Induction of apoptosis in oral cancer cells: agents and mechanisms for potential therapy and prevention

Oral cancer is one of the most disfiguring types of cancer, since the surgical removal of the tumor may result in facial distortion. Oral cancer is also known to exhibit "field cancerization", resulting in the development of a second primary tumor. Furthermore, the five-year survival rate of this disease has remained approximately 50% during the past 30 years. Prevention and early detection/treatment of oral cancer could significantly improve the quality of life for individuals at risk. Recently, the targeted elimination of oral squamous cell carcinoma cells by inducing apoptosis has emerged as a valued strategy to combat oral cancer. Studies utilizing a variety of chemical or biological interventions demonstrated promising results for induction of apoptosis in oral malignant cells. This review summarizes the results of a number of investigations focused specifically on induction of apoptosis in oral cancer cells by synthetic compounds and naturally occurring chemopreventive agents with apoptotic potential.

Protective effects of green tea extracts (polyphenon E and EGCG) on human cervical lesions

We investigated clinical efficacy of green tea extracts (polyphenon E; poly E and (-)-epigallocatechin-3-gallate [EGCG]) delivered in a form of ointment or capsule in patients with human papilloma virus (HPV) infected cervical lesions. Fifty-one patients with cervical lesions (chronic cervicitis, mild dysplasia, moderate dysplasia and severe dysplasia) were divided into four groups, as compared with 39 untreated patients as a control. Poly E ointment was applied locally to 27 patients twice a week. For oral delivery, a 200 mg of poly E or EGCG capsule was taken orally every day for eight to 12 weeks. In the study, 20 out of 27 patients (74%) under poly E ointment therapy showed a response. Six out of eight patients under poly E ointment plus poly E capsule therapy (75%) showed a response, and three out of six patients (50%) under poly E capsule therapy showed a response. Six out of 10 patients (60%) under EGCG capsule therapy showed a response. Overall, a 69% response rate (35/51) was noted for treatment with green tea extracts, as compared with a 10% response rate (4/39) in untreated controls (P<0.05). Thus, the data collected here demonstrated that green tea extracts in a form of ointment and capsule are effective for treating cervical lesions, suggesting that green tea extracts can be a potential therapy regimen for patients with HPV infected cervical lesions.

Caspase-independent apoptosis induced by evening primrose extract in Ehrlich ascites tumor cells

We previously demonstrated that evening primrose extract (EPE) induced apoptosis in Ehrlich ascites tumor cells, while mouse embryo fibroblast cells (NIH3T3) used as a normal cell model, showed no effect of cell viability by treatment of EPE. Furthermore, our results demonstrated the rapid increase in intracellular peroxides levels, loss of mitochondrial membrane potential and the release of cytochrome c to cytosol, suggesting that the rapid increase in intracellular peroxides levels after addition of EPE triggers off induction of apoptosis. In this study, we identified that EPE elicited the translocation of Bax to mitochondria and apoptosis-inducing factor (AIF) to nuclei, but no activation of caspase-3-like protease. We also demonstrated that the rapid EPE-induced increase in hydrogen peroxide levels caused the translocation of Bax to mitochondria, and then mitochondrial cytochrome c was released. One of the main consequences of mitochondrial cytochrome c release is the activation of caspase-3. However, no caspase-3 activation was observed. On the other hand, AIF was translocated from mitochondria to nuclei. The EPE-induced translocation of AIF was suppressed with the addition of catalase, suggesting that the rapid intracellular peroxide levels after addition of EPE triggers off induction of apoptosis, which is AIF-mediated and caspase-independent.

Green tea extract inhibits angiogenesis of human umbilical vein endothelial cells through reduction of expression of VEGF receptors

Epidemiological and animal studies have indicated that consumption of green tea is associated with a reduced risk of developing certain forms of cancer. However, the inhibitory mechanism of green tea in angiogenesis, an important process in tumor growth, has not been well established. In the present study, green tea extract (GTE) was tested for its ability to inhibit cell viability, cell proliferation, cell cycle dynamics, vascular endothelial growth factor (VEGF) and expression of VEGF receptors fms-like tyrosine kinase (Flt-1) and fetal liver kinase-1/Kinase insert domain containing receptor (Flk-1/KDR) in vitro using human umbilical vein endothelial cells (HUVECs). GTE in culture media did not affect cell viability but significantly reduced cell proliferation dose-dependently and caused a dose-dependent accumulation of cells in the G1 phase. The decrease of the expression of Flt-1 and KDR/Flk-1 in HUVEC by GTE was detected with immunohistochemical and Western blotting methods. These results suggest that GTE may have preventive effects on tumor angiogenesis and metastasis through reduction of expression of VEGF receptors.

Role of intracellular reactive oxygen species and mitochondrial dysfunction in evening primrose extract-induced apoptosis in Ehrlich ascites tumor cells

Herbal medicines are increasingly being utilized to treat a wide variety of disease processes. Evening primrose extract (EPE) is extracted from Oenothera biennis L., one species of evening primroses, which has been shown to have several pharmacological effects. However, anti-tumor activity in the extract of defatted seeds of O. biennis L. has not been defined thus far. In this study, we identified the major biochemical changes upon EPE treatment and investigated the functional relationship between these changes. We found that EPE-induced apoptosis in Ehrlich ascites tumor cells as evidenced by morphological changes. Furthermore, our results demonstrated rapid increase of intracellular peroxides levels, loss of mitochondrial membrane potential and the release of cytochrome c from mitochondria to cytosol. These results suggest that the rapid increase of intracellular peroxides levels after addition of EPE triggers off induction of apoptosis.

Selective inhibition of ADAMTS-1, -4 and -5 by catechin gallate esters

Three mammalian ADAMTS enzymes, ADAMTS-1, -4 and -5, are known to cleave aggrecan at certain glutamyl bonds and are considered to be largely responsible for cartilage aggrecan catabolism observed during the development of arthritis. We have previously reported that certain catechins, polyphenolic compounds found in highest concentration in green tea (Camellia sinensis), are capable of inhibiting cartilage aggrecan breakdown in an in vitro model of cartilage degradation. We have now cloned and expressed recombinant human ADAMTS-1, -4 and -5 and report here that the catechin gallate esters found in green tea potently inhibit the aggrecan-degrading activity of these enzymes, with submicromolar IC50 values. Moreover, the concentration needed for total inhibition of these members of the ADAMTS group is approximately two orders of magnitude lower than that which is needed to partially inhibit collagenase or ADAM-10 activity. Catechin gallate esters therefore provide selective inhibition of certain members of the ADAMTS group of enzymes and could constitute an important nutritional aid in the prevention of arthritis as well as being part of an effective therapy in the treatment of joint disease and other pathologies involving the action of these enzymes.

A major constituent of green tea, EGCG, inhibits the growth of a human cervical cancer cell line, CaSki cells, through apoptosis, G(1) arrest, and regulation of gene expression

A constituent of green tea, (-)-epigallocatechin-3-gallate (EGCG) has been known to possess antiproliferative properties. In this study, we investigated the anticancer effects of EGCG in human papillomavirus (HPV)-16 associated cervical cancer cell line, CaSki cells. The growth inhibitory mechanism(s) and regulation of gene expression by EGCG were also evaluated. EGCG showed growth inhibitory effects in CaSki cells in a dose-dependent fashion, with an inhibitory dose (ID)(50) of approximately 35 microM. When CaSki cells were further tested for EGCG-induced apoptosis, apoptotic cells were significantly observed after 24 h at 100 microM EGCG. In contrast, an insignificant induction of apoptotic cells was observed at 35 microM EGCG. However, cell cycles at the G1 phase were arrested at 35 microM EGCG, suggesting that cell cycle arrests might precede apoptosis. When CaSki cells were tested for their gene expression using 384 cDNA microarray, an alteration in the gene expression was observed by EGCG treatment. EGCG downregulated the expression of 16 genes over time more than twofold. In contrast, EGCG upregulated the expression of four genes more than twofold, suggesting a possible gene regulatory role of EGCG. This data supports that EGCG can inhibit cervical cancer cell growth through induction of apoptosis and cell cycle arrest as well as regulation of gene expression in vitro. Furthermore, in vivo antitumor effects of EGCG were also observed. Thus, EGCG likely provides an additional option for a new and potential drug approach for cervical cancer patients.

Cellular thiol status-dependent inhibition of tumor cell growth via modulation of retinoblastoma protein phosphorylation by (-)-epigallocatechin

Tea polyphenols have been shown to inhibit tumor cell growth, but there is limited information on their effects on cell signaling and cell cycle control pathways. We have shown the involvement of such mechanisms as activation of mitogenic activated protein kinases, decreases in ornithine decarboxylase activity and in cellular thiol levels, elicitation of mitochondrial cytochrome c release, and activation of caspases by the green tea galloyl polyphenol, epigallocatechin (EGC). In the current study, we sought to determine how EGC alters cell cycle and its related control factors in its growth inhibitory effect in Ehrlich ascites tumor cells. The significant finding here is that EGC caused a dose-dependent accumulation of cells in the G1 phase and a decrease in the phosphorylation of the retinoblastoma (Rb) protein, which was also in a cellular thiol-dependent manner. The involvement of a cellular thiol-dependent modulation in Rb phosphorylation leading to the regulation of tumor cell growth by a green tea polyphenol is a novel observation, to the best of our knowledge.