Apigenin inhibited migration and invasion of human ovarian cancer A2780 cells through focal adhesion kinase

The Conyza triloba extracts with high chlorophyll content and free radical scavenging activity had anticancer activity in cell lines

The discovery of anticancer agents paradigm has been shifted to natural resources to overcome the toxicity of many synthetic agents at early clinical stages. In the present study, the antimutagenic, anticancer, phytochemistry, and free radical scavenging activities of five extracts of Conyza triloba were investigated. Extracts II (water : methanol), III (methylene chloride), and IV (methylene chloride : methanol) had the highest chlorophyll content and the highest superoxide scavenging, and metal chelating activities comparable to that of trolox. They also showed DPPH^• scavenging activities better than that of α-tocopherol. Virtually all extracts exerted a strong (>40% reduction) antimutagenic activity against sodium azide and benzopyrene. Extracts II, III, and IV showed a remarkable growth inhibition profile with GI₅₀ of 0.07–0.87 μg for Hepa1c1c7 and H4IIE1, A549, HT29, and PC3 cell lines and totally abated the growth of all cell lines, except for the breast cells, at 0.3–7.0 μg. The present study found a strong correlation between the chlorophyll content of Conyza extracts and their DDPH scavenging, metal chelating, and in vitro cytotoxic and cytostatic activities most probably through triggering apoptosis. This study could offer a platform for future studies and help selecting the vital features that identify the extract with potential anticancer activities.

Molecular basis for the action of a dietary flavonoid revealed by the comprehensive identification of apigenin human targets

Flavonoids constitute the largest class of dietary phytochemicals, adding essential health value to our diet, and are emerging as key nutraceuticals. Cellular targets for dietary phytochemicals remain largely unknown, posing significant challenges for the regulation of dietary supplements and the understanding of how nutraceuticals provide health value. Here, we describe the identification of human cellular targets of apigenin, a flavonoid abundantly present in fruits and vegetables, using an innovative high-throughput approach that combines phage display with second generation sequencing. The 160 identified high-confidence candidate apigenin targets are significantly enriched in three main functional categories: GTPase activation, membrane transport, and mRNA metabolism/alternative splicing. This last category includes the heterogeneous nuclear ribonucleoprotein A2 (hnRNPA2), a factor involved in splicing regulation, mRNA stability, and mRNA transport. Apigenin binds to the C-terminal glycine-rich domain of hnRNPA2, preventing hnRNPA2 from forming homodimers, and therefore, it perturbs the alternative splicing of several human hnRNPA2 targets. Our results provide a framework to understand how dietary phytochemicals exert their actions by binding to many functionally diverse cellular targets. In turn, some of them may modulate the activity of a large number of downstream genes, which is exemplified here by the effects of apigenin on the alternative splicing activity of hnRNPA2. Hence, in contrast to small-molecule pharmaceuticals designed for defined target specificity, dietary phytochemicals affect a large number of cellular targets with varied affinities that, combined, result in their recognized health benefits.

Vascular endothelial growth factor C enhances cervical cancer migration and invasion via activation of focal adhesion kinase

Vascular endothelial growth factor C (VEGF-C) is correlated positively with clinical cervical cancer metastasis and survival. Previously we showed that VEGF-C directly activated actin-binding protein moesin, leading to the formation of membrane protrusions. However, whether VEGF-C alters cervical cancer cell adhesion to the extra-cellular matrix is currently unknown. In this study, we investigated the effects of VEGF-C on the formation of focal adhesion complexes, which provide anchoring sites for cell attachment to the extracellular matrix. On cultured cervical carcinoma cell line SiHa cells, VEGF-C enhanced focal adhesion kinase (FAK) phosphorylation. As a result, VEGF-C led to increased formation of focal adhesion complexes and enhanced migration and invasion, which was reversed by siRNA abrogating FAK. VEGF-C resulted in increased interaction of its receptor Flt-4 with non-receptor tyrosine kinase c-Src, leading to c-Src phosphorylation. The specific inhibitor of c-Src kinase, PP2, or the transfection with specific c-Src siRNA largely impaired VEGF-C-enhanced FAK phosphorylation, suggesting that Flt-4/c-Src cascade plays a central role in these processes. These results implied that VEGF-C promotes cervical cancer metastasis by activation of FAK protein through Flt-4/c-Src pathway.

Flavonoids and cancer prevention: a review of the evidence

The objective of this work is to review data from epidemiological and preclinical studies addressing the potential benefits of diets based on flavonoids for cancer prevention. Flavonoids are subdivided into subclasses including flavonols, flavones, flavanones, flavan-3-ols, anthocyanidins, and isoflavones. Epidemiological studies suggest dietary intake of flavonoids may reduce the risk of tumors of the breast, colon, lung, prostate, and pancreas. However, some studies have reported inconclusive or even harmful associations. A major challenge in the interpretation of epidemiological studies is that most of the data originate from case-control studies and retrospective acquisition of flavonoid intake. Differences in agricultural, sociodemographics, and lifestyle factors contribute to the heterogeneity in the intake of flavonoids among populations residing in the United States, Europe, and Asia. Dose and timing of exposure may influence the anticancer response to flavonoid-rich diets. A limited number of intervention trials of flavonoids have documented cancer preventative effects. Proposed anticancer mechanisms for flavonoids are inhibition of proliferation, inflammation, invasion, metastasis, and activation of apoptosis. Prospective studies with larger sample sizes are needed to develop biomarkers of flavonoid intake and effect. Mechanistic studies are needed to ascertain how flavonoid-rich diets influence gene regulation for cancer prevention.

Apigenin and its impact on gastrointestinal cancers

Apigenin (4',5,7-trihydroxyflavone, 5,7-dihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) is a flavonoid found in many fruits, vegetables, and herbs, the most abundant sources being the leafy herb parsley and dried flowers of chamomile. Present in dietary sources as a glycoside, it is cleaved in the gastrointestinal lumen to be absorbed and distributed as apigenin itself. For this reason, the epithelium of the gastrointestinal tract is exposed to higher concentrations of apigenin than tissues at other locations. This would also be true for epithelial cancers of the gastrointestinal tract. We consider the evidence for actions of apigenin that might hinder the ability of gastrointestinal cancers to progress and spread. Apigenin has been shown to inhibit cell growth, sensitize cancer cells to elimination by apoptosis, and hinder the development of blood vessels to serve the growing tumor. It also has actions that alter the relationship of the cancer cells with their microenvironment. Apigenin is able to reduce cancer cell glucose uptake, inhibit remodeling of the extracellular matrix, inhibit cell adhesion molecules that participate in cancer progression, and oppose chemokine signaling pathways that direct the course of metastasis into other locations. As such, apigenin may provide some additional benefit beyond existing drugs in slowing the emergence of metastatic disease.

Apigenin inhibits NNK-induced focal adhesion kinase activation in pancreatic cancer cells

OBJECTIVES

Tobacco-derived carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) activates β-adrenergic receptor (β-AR) signaling through Src/focal adhesion kinases (FAKs)/mitogen-activated protein kinase to modulate proliferation, migration, and survival. Apigenin (4', 5, 7-trihydroxyflavone) is reported to attenuate proliferation and migration of cancer cells. This study was designed to determine the effects of apigenin on NNK-induced procarcinogenesis using human pancreatic cancer cells BxPC-3 and MIA PaCa-2, which express β-AR.

METHODS

Proliferation and migration were assessed by standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and scratch assays. β-AR, FAK/mitogen-activated protein kinase and extracellular signal-regulated kinase (ERK) expression and activation were assessed by Western blotting and real-time polymerase chain reaction.

RESULTS

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone caused a dose- and time-dependent increase in BxPC-3 and MIA PaCa-2 cell proliferation that was inhibited by propranolol or apigenin. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone also stimulated a time-dependent increase in FAK and ERK activation that was suppressed by propranolol or apigenin. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone-enhanced gap closure at 24 hours was prevented by either propranolol or apigenin.

CONCLUSION

Apigenin suppressed the effects of NNK on pancreatic cancer cell proliferation and migration that are mediated through the β-AR and its downstream signals FAK and ERK activation. These findings suggest a therapeutic role for this natural phytochemical in attenuating the procarcinogenic effects of NNK on pancreatic cancer proliferation and migration.

Effect of the phenolic compounds apigenin and carnosic acid on oral carcinogenesis in hamster induced by DMBA

OBJECTIVE

To investigate oral carcinogenesis in hamster induced by the topical application of 7,12-dimethyl benzanthracene (DMBA) to evaluate the different lesions produced and the possible preventive effects of the phenolic compounds apigenin (flavone) and carnosic acid (diterpene).

MATERIALS AND METHODS

Thirty-two Syrian hamsters were divided into three groups: I: 0.5% DMBA (n = 12); II: 0.5% DMBA + potassium apigenin (n = 8); III: 0.5% DMBA + carnosic acid (n = 12). All the animals were sacrificed after 11 weeks, and a macroscopic and light microscopic study was made of the lesions.

RESULTS

The largest number of neoplasms, showing the most aggressive biological behavior, corresponded to the control group. The group treated with potassium apigenin ranked second in tumor incidence, although the tumors were not very aggressive behavior. In the group treated with carnosic acid, only one malignancy was recorded, showing the smallest volume of all the recorded tumor lesions.

CONCLUSIONS

Our findings indicate that both potassium apigenin and carnosic acid have chemoprotective effects against carcinogenesis induced by DMBA in hamster.

Apigenin induces apoptosis in human leukemia cells and exhibits anti-leukemic activity in vivo

In this study, we investigated the functional role of Akt and c-jun-NH(2)-kinase (JNK) signaling cascades in apigenin-induced apoptosis in U937 human leukemia cells and anti-leukemic activity of apigenin in vivo. Apigenin induced apoptosis by inactivation of Akt with a concomitant activation of JNK, Mcl-1 and Bcl-2 downregulation, cytochrome c release from mitochondria, and activation of caspases. Constitutively active myristolated Akt prevented apigenin-induced JNK, caspase activation, and apoptosis. Conversely, LY294002 and a dominant-negative construct of Akt potentiated apigenin-induced apoptosis in leukemia cells. Interruption of the JNK pathway showed marked reduction in apigenin-induced caspase activation and apoptosis in leukemia cells. Furthermore, in vivo administration of apigenin resulted in attenuation of tumor growth in U937 xenografts accompanied by inactivation of Akt and activation of JNK. Attenuation of tumor growth in U937 xenografts by apigenin raises the possibility that apigenin may have clinical implications and can be further tested for incorporating in leukemia treatment regimens.

Research advances at the Institute for Nutritional Sciences at Shanghai, China

Nutrition-related health issues have emerged as a major threat to public health since the rebirth of the economy in China starting in the 1980s. To meet this challenge, the Chinese Academy of Sciences established the Institute for Nutritional Sciences (INS) at Shanghai, China ≈ 8 y ago. The mission of the INS is to apply modern technologies and concepts in nutritional research to understand the molecular mechanism and provide means of intervention in the combat against nutrition-related diseases, including type 2 diabetes, metabolic syndrome, obesity, cardiovascular diseases, and many types of cancers. Through diligent and orchestrated efforts by INS scientists, graduate students, and research staff in the past few years, the INS has become the leading institution in China in the areas of basic nutritional research and metabolic regulation. Scientists at the INS have made important progress in many areas, including the characterization of genetic and nutritional properties of the Chinese population, metabolic control associated with nutrient sensing, molecular mechanisms underlying glucose and lipid metabolism, regulation of metabolism by adipokines and inflammatory pathways, disease intervention using functional foods or extracts of Chinese herbs, and many biological studies related to carcinogenesis. The INS will continue its efforts in understanding the optimal nutritional needs for Chinese people and the molecular causes associated with metabolic diseases, thus paving the way for effective and individualized intervention in the future. This review highlights the major research endeavors undertaken by INS scientists in recent years.

The orphan nuclear receptor EAR2 is overexpressed in colorectal cancer and it regulates survivability of colon cancer cells

EAR2 is a member of the chick ovalbumin upstream promoter-transcription factors (COUP-TFs). COUP-TFs belong to orphan nuclear receptors and regulate many biological processes. Little is known regarding EAR2 in cancer, though much progress has been made in understanding the function of other COUP-TF members. The aim of this study is to investigate the expression and possible function of EAR2 in colorectal cancer. We determined expression of EAR2 in human primary colorectal malignant tumors and their paired adjacent normal colorectal tissues. We found that expression of EAR2 was upregulated in colorectal tumors. Knockdown of EAR2 induced apoptosis of colon cancer cells, suggesting that EAR2 may function to regulate survivability of colon cancer cells. In vivo tumor study demonstrated that knockdown of EAR2 inhibited the xenograft growth of colon cancer cells. We found that knockdown of EAR2 inhibited the expression of X-linked inhibitor of apoptosis protein (XIAP), suggesting that EAR2 regulates cell survivability, at least partly, through XIAP. In this manuscript, we demonstrated that expression of EAR2 was elevated in colorectal cancer and knockdown of EAR2 reduced survivability and tumor growth of colon cancer cells. Our results suggest that EAR2 plays an important role in development of colorectal cancer. The findings also suggest that EAR2 may serve as a potential therapeutic target of colorectal cancer.

Activating transcription factor 3 regulates survivability and migration of vascular smooth muscle cells

Activating transcription factor 3 (ATF3) is a member of the ATF/CREB (CAMP responsive element binding protein) family of transcription factors. The expression and the function of ATF3 in vascular smooth muscle cells (VSMCs) remain unknown. The aim of this work is to determine the expression and possible function of ATF3 in VSMCs. We found that VSMCs expressed ATF3, and expression of ATF3 in VSMCs was induced by a variety of stimuli including serum, angiotensin II, and H(2)O(2). Knockdown of ATF3 induced apoptosis of VSMCs, caspase-3 cleavage, and cytochrome c release. The results suggest that ATF3 regulates survivability of VSMCs. Moreover, we found that overexpression of ATF3 promoted migration of VSMCs and induced expression of matrix metalloproteinase 1, 3, and 13. These results suggest that ATF3 plays a role in regulating migration of VSMCs. In addition, we found that the expression of ATF3 was upregulated in smooth muscle cells in the injured mouse femoral arteries compared with the uninjured control group. These results suggest that ATF3 is relevant to disease physiology.

Apigenin inhibits hepatoma cell growth through alteration of gene expression patterns

Apigenin, a common plant flavonoid, has been shown to possess anti-tumor properties; however, the underlying molecular mechanisms are still not completely understood. In the present study, we investigated the effects of apigenin on human hepatoma Huh7 cell proliferation, cell cycle distribution, apoptosis, and colony formation in vitro, as well as on the tumorigenicity of Huh7 cells in vivo. To get more insight into the mechanism of apigenin action, we performed genome-wide expression profiling of apigenin-treated Huh7 cells using cDNA microarrays (Agilent Whole Human Genome Oligo Microarray) that contain 41,000 genes. Ten of the most differentially expressed genes (≧5-fold changes) were selected for further evaluation by quantitative RT-PCR (qPCR) and Western blot analyses. Notably, apigenin (5-20 μg/ml) remarkably inhibited Huh7 cell proliferation and colony formation as compared to the vehicle control, which was in a dose-dependent manner. Accompanying with the decreased growth, apigenin-treated cells showed a cell cycle arrest at G2/M phase and an increased rate of apoptosis. Moreover, the xenografts derived from Huh7 cells were significantly (p<0.05) retarded by the delivery of apigenin (50 μg/mouse/day) relative to the control counterparts. Gene expression profile analysis revealed that 1336 genes were up-regulated and 428 genes were down-regulated by apigenin. The down-regulation of interleukin-4 receptor and ubiquitin specific protease 18 and the up-regulation of SLC27A3 and chemokine (C-C motif) receptor 2 were further confirmed by the qPCR and Western blot results. In conclusion, apigenin exhibits inhibitory effects on hepatoma cell growth, which is likely mediated through alteration of gene expression profiles.

F-actin reorganization and inactivation of rho signaling pathway involved in the inhibitory effect of Coptidis Rhizoma on hepatoma cell migration

HYPOTHESIS

Hepatocellular carcinoma (HCC) is one of the most malignant human tumors and one of the risk factors is its highly metastatic property. Coptidis Rhizoma aqueous extract (CRAE) is able to suppress the migration and invasion of HCC cells, MHCC97-L, and F-actin reorganization and Rho signaling inhibition is involved.

MAIN METHODS

CRAE was prepared and analyzed by high-performance liquid chromatography combined with mass spectrometry. The cytotoxicity and antimigration action of CRAE on MHCC97-L cells were evaluated; Immunofluorescence and immunoblotting were used to investigate the proposed mechanism of CRAE action.

KEY FINDINGS

Chemical analysis reveals that the active components in CRAE are berberine and berberine-like alkaloids. CRAE exhibits a significant inhibitory effect on MHCC97-L cell migration as indicated by wound-healing and invasion-chamber assays. No significant alteration of matrix metalloproteinases and urokinase-type plasminogen activator (uPA) expression were observed in MHCC97-L cells exposed to CRAE. Reduction of F-actin polymerization and damage to cytoskeleton network in MHCC97-L cells were observed after CRAE treatment. Furthermore, it was found that CRAE significantly downregulated the Rho/ROCK signaling pathway.

SIGNIFICANCE

These results indicate that CRAE may act as a Rho/ROCK signaling inhibitor to suppress MHCC97-L cell migration in vitro and suggested that total alkaloids in Coptidis Rhizoma may be a potential agent for suppressing liver cancer invasion.

IL-8-induced neutrophil chemotaxis is mediated by Janus kinase 3 (JAK3)

Janus kinase 3 (JAK3) is a non-receptor tyrosine kinase vital to the regulation of T-cells. We report that JAK3 is a mediator of interleukin-8 (IL-8) stimulation of a different class of hematopoietic relevant cells: human neutrophils. IL-8 induced a time- and concentration-dependent activation of JAK3 activity in neutrophils and differentiated HL-60 leukemic cells. JAK3 was more robustly activated by IL-8 than other kinases: p70S6K, mTOR, MAPK or PKC. JAK3 silencing severely inhibited IL-8-mediated chemotaxis. Thus, IL-8 stimulates chemotaxis through a mechanism mediated by JAK3. Further, JAK3 activity and chemotaxis were inhibited by the flavonoid apigenin (4',5,7-trihydroxyflavone) at ∼5nM IC(50). These new findings lay the basis for understanding the molecular mechanism of cell migration as it relates to neutrophil-mediated chronic inflammatory processes.

Estrogen receptor-alpha promotes breast cancer cell motility and invasion via focal adhesion kinase and N-WASP

The ability of cancer cells to move and invade the surrounding environment is the basis of local and distant metastasis. Cancer cell movement requires dynamic remodeling of the cytoskeleton and cell membrane and is controlled by multiprotein complexes including focal adhesion kinase (FAK) or the Neural Wiskott-Aldrich Syndrome Protein (N-WASP). We show that 17β-estradiol induces phosphorylation of FAK and its translocation toward membrane sites where focal adhesion complexes are assembled. This process is triggered via a Gα/Gβ protein-dependent, rapid extranuclear signaling of estrogen receptor α interacts in a multiprotein complex with c-Src, phosphatidylinositol 3-OH kinase, and FAK. Within this complex FAK autophosphorylation ensues, and activated FAK recruits the small GTPase cdc42, which, in turn, triggers N-WASP phosphorylation. This results in the translocation of Arp2/3 complexes at sites where membrane structures related to cell movement are formed. Recruitment of FAK and N-WASP is necessary for cell migration and invasion induced by 17β-estradiol in breast cancer cells. Our findings identify an original mechanism through which estrogen promotes breast cancer cell motility and invasion. This information helps to understand the effects of estrogen on breast cancer metastasis and may provide new targets for therapeutic interventions.

Apigenin: a promising molecule for cancer prevention

Apigenin, a naturally occurring plant flavone, abundantly present in common fruits and vegetables, is recognized as a bioactive flavonoid shown to possess anti-inflammatory, antioxidant and anticancer properties. Epidemiologic studies suggest that a diet rich in flavones is related to a decreased risk of certain cancers, particularly cancers of the breast, digestive tract, skin, prostate and certain hematological malignancies. It has been suggested that apigenin may be protective in other diseases that are affected by oxidative process, such as cardiovascular and neurological disorders, although more research needs to be conducted in this regard. Human clinical trials examining the effect of supplementation of apigenin on disease prevention have not been conducted, although there is considerable potential for apigenin to be developed as a cancer chemopreventive agent.

Apigenin inhibits cell growth and alters expression of multiple genes in human hepatoma cell line Huh-7

AIM: To investigate the effects of apigenin on cell growth and gene expression in human hepatoma cell line Huh-7.

METHODS: After Huh-7 cells was cultured and treated with different concentrations of apigenin, cell proliferation was measured by colorimetric methyl thiazolyl tetrazolium (MTT) assay; cell clonogenicity was detected by colony-forming assay; and cell cycle distribution and apoptosis were examined by flow cytometry. The impact of apigenin on the tumorigenicity of Huh-7 cells in nude mice was also detected. The differential gene expression between cells treated and untreated with apigenin was detected by cDNA microarray and verified by quantitative real-time reverse transcription-polymerase chain reaction and Western blot.

RESULTS: Compared with untreated cells, cells treated with apigenin exhibited a marked growth inhibition. The half maximal inhibitory concentration (IC₅₀) of apigenin on cell growth was approximately 10.5 mg/L ± 0.3 mg/L. Apigenin treatment could cause a cell cycle block at G2/M phase, decrease the percentage of cells at G₀/G₁ phase, promote apoptosis, and inhibit the tumorigenicity of Huh-7 cells in vivo. Apigenin treatment could also dramatically alter the expression of 1 764 functionally related genes in Huh-7 cells. Of these differentially expressed genes, the majority are involved in nucleic acid binding and transport, enzyme catalytic activity regulation, transcriptional regulation, cytoskeletal structure and/or adhesion, signal transduction, metabolism, apoptosis or the immune response. Of note, apigenin could significantly downregulate the expression of interleukin-4 receptor and ubiquitin-specific protease 18.

CONCLUSION: Apigenin partially inhibits Huh-7 cell growth in vitro and in vivo by blocking cell cycle at G₂/M phase and promoting apoptosis. Apigenin treatment alters the expression of multiple genes in Huh-7 cells.

Prolyl hydroxylase-3 is down-regulated in colorectal cancer cells and inhibits IKKbeta independent of hydroxylase activity

BACKGROUND & AIMS

Prolyl hydroxylase (PHD) hydroxylates hypoxia inducible factor (HIF) alpha, leading to HIFalpha degradation. The PHD family comprises PHD1, PHD2, and PHD3. The enzymatic activity of PHDs is O(2)-dependent, so PHDs are believed to be oxygen sensors as well as tumor suppressors. However, the expression pattern of PHDs in colorectal cancer and the correlation between their expression level and tumorigenesis is unclear.

METHODS

We determined the expression of PHDs in 60 human primary colorectal carcinoma tissues, paired with normal colorectal tissues. PHD3 expression levels were knocked down using small interfering RNA (siRNA); cells were analyzed by immunoblotting, immunoprecipitation, and histochemical analyses. In vivo tumor growth was analyzed in nu/nu mice.

RESULTS

Expression of PHD3 is decreased in colorectal cancer tissues. Decreased expression of PHD3 is associated with higher tumor grade and metastasis. PHD3 inhibits phosphorylation of inhibitor of kappaB (IkappaB) kinase (IKK) beta and activation of (NF) kappaB, independent of its hydroxylase activity. PHD3 associates with IKKbeta but does not target it for destruction; instead, PHD3 blocks the interaction between IKKbeta and Hsp90 that is required for phosphorylation of IKKbeta. Knockdown of PHD3 increased resistance of colorectal cancer cells to the effects of tumor necrosis factor-alpha and tumorigenesis.

CONCLUSIONS

PHD3 appears to be a tumor suppressor in colorectal cancer cells that inhibits IKKbeta/NF-kappaB signaling, independent of its hydroxylase activity. Activation of NF-kappaB has been observed in colon cancer. Determination of PHD3 status could aid targeted therapy selection for patients with colorectal tumors that have increased NF-kappaB activity.

In vitro anti-leukemic activity of the ethno-pharmacological plant Scutellaria orientalis ssp. carica endemic to western Turkey

AIM OF THIS STUDY

Within the genus Scutellaria various species are used in different folk medicines throughout Asia. Traditional Chinese Medicine (TCM) uses S. baicalensis (Labiatae) to treat various inflammatory conditions. The root shows strong anticancer properties in vitro and was suggested for clinical trials against multiple myeloma. Further, S. barbata was successfully tested against metastatic breast cancer in a phase I/II trial. Therefore, we investigated the anti-cancer properties of S. orientalis L. ssp. carica Edmondson, an endemic subspecies from the traditional medicinal plant S. orientalis L. in Turkey, which is used to promote wound healing and to stop haemorrhage.

MATERIALS AND METHODS

Freeze-dried plant material was extracted with petroleum ether, dichloromethane, ethyl acetate, and methanol and the bioactivity of these extracts was analysed by proliferation assay, cell death determination, and by investigating protein expression profiles specific for cell cycle arrest and apoptosis.

RESULTS

The strongest anti-leukemic activity was shown by the methanol extract, which contained apigenin, baicalein, chrysin, luteolin and wogonin, with an IpC50 of 43 microg/ml (corresponding to 1.3mg/ml of dried plant material) which correlated with cyclin D1- and Cdc25A suppression and p21 induction. At 132 microg/ml (=4 mg/ml of the drug) this extract caused genotoxic stress indicated by substantial phosphorylation of the core histone H2AX (gamma-H2AX) followed by activation of caspase 3 and signature-type cleavage of PARP resulting in a 55% apoptosis rate after 48 hours of treatment.

CONCLUSIONS

Here, we report for the first time that S. orientalis L. ssp. carica Edmondson exhibited potent anti-leukaemic properties likely through the anti-proliferative effect of baicalein and the genotoxic property of wogonin.

The chemopreventive bioflavonoid apigenin inhibits prostate cancer cell motility through the focal adhesion kinase/Src signaling mechanism

Prostate cancer mortality is primarily attributed to metastatic rather than primary, organ-confined disease. Acquiring a motile and invasive phenotype is an important step in development of tumors and ultimately metastasis. This step involves remodeling of the extracellular matrix and of cell-matrix interactions, cell movement mediated by the actin cytoskeleton, and activation of focal adhesion kinase (FAK)/Src signaling. Epidemiologic studies suggest that the metastatic behavior of prostate cancer may be an ideal target for chemoprevention. The natural flavone apigenin is known to have chemopreventive properties against many cancers, including prostate cancer. Here, we study the effect of apigenin on motility, invasion, and its mechanism of action in metastatic prostate carcinoma cells (PC3-M). We found that apigenin inhibits PC3-M cell motility in a scratch-wound assay. Live cell imaging studies show that apigenin diminishes the speed and affects directionality of cell motion. Alterations in the cytoskeleton are consistent with impaired cell movement in apigenin-treated cells. Apigenin treatment leads to formation of "exaggerated filopodia," which show accumulation of focal adhesion proteins at their tips. Furthermore, apigenin-treated cells adhere more strongly to the extracellular matrix. Additionally, apigenin decreases activation of FAK and Src, and phosphorylation of Src substrates FAK Y576/577 and Y925. Expression of constitutively active Src blunts the effect of apigenin on cell motility and cytoskeleton remodeling. These results show that apigenin inhibits motility and invasion of prostate carcinoma cells, disrupts actin cytoskeleton organization, and inhibits FAK/Src signaling. These studies provide mechanistic insight into developing novel strategies for inhibiting prostate cancer cell motility and invasiveness.

Apigenin inhibits proliferation of ovarian cancer A2780 cells through Id1

Apigenin, a common dietary flavonoid, has been shown to possess anti-tumor properties. However, the mechanism by which apigenin inhibits cancer cells is not fully understood. Id1 (inhibitor of differentiation or DNA binding protein 1) contributes to tumorigenesis by stimulating cell proliferation, inhibiting cell differentiation and facilitating tumor neoangiogenesis. Elevated Id1 is found in ovarian cancers and its level correlates with the malignant potential of ovarian tumors. Therefore, Id1 is a potential target for ovarian cancer treatment. Here, we demonstrate that apigenin inhibits proliferation and tumorigenesis of human ovarian cancer A2780 cells through Id1. Apigenin suppressed the expression of Id1 through activating transcription factor 3 (ATF3). Our results may elucidate a new mechanism underlying the inhibitory effects of apigenin on cancer cells.