Genistein-induced neuronal apoptosis and G2/M cell cycle arrest is associated with MDC1 up-regulation and PLK1 down-regulation

Compounds from Natural Sources as Protein Kinase Inhibitors

The advantage of natural compounds is their lower number of side-effects when compared to most synthetic substances. Therefore, over the past several decades, the interest in naturally occurring compounds is increasing in the search for new potent drugs. Natural compounds are playing an important role as a starting point when developing new selective compounds against different diseases. Protein kinases play a huge role in several diseases, like cancers, neurodegenerative diseases, microbial infections, or inflammations. In this review, we give a comprehensive view of natural compounds, which are/were the parent compounds in the development of more potent substances using computational analysis and SAR studies.

Synthesis and cytotoxic activity of 7,4’-O-modified genistein amino acid derivatives

Fifteen 7,4’- O-modified genistein amino acid derivatives are synthesized through nucleophilic substitution and hydrolysis, followed by condensation with diverse amino acid esters. The antiproliferative activity of all the synthesized compounds is evaluated against three cancer cell lines (MGC-803, HeLa, HCT-116) and one normal cell line (HUVEC) using 5-fluorouracil (5-Fu) as the positive control. The results show that methyl [2-({5-hydroxy-3-[4-(2-{[3-(4-hydroxyphenyl)-1-methoxy-1-oxopropan-2-yl]amino}-2-oxoethoxy)phenyl]-4-oxo-4 H-chromen-7-yl}oxy)acetyl] tyrosinate exhibits significant antiproliferative activity against the MGC-803 cell line with an IC50 value of 8.52 µM, and its inhibitory effects on HeLa and HCT-116 cancer cells are stronger than that of the positive control drug 5-Fu.

Molecular Targets of Genistein and Its Related Flavonoids to Exert Anticancer Effects

Increased health awareness among the public has highlighted the health benefits of dietary supplements including flavonoids. As flavonoids target several critical factors to exert a variety of biological effects, studies to identify their target-specific effects have been conducted. Herein, we discuss the basic structures of flavonoids and their anticancer activities in relation to the specific biological targets acted upon by these flavonoids. Flavonoids target several signaling pathways involved in apoptosis, cell cycle arrest, mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/AKT kinase, and metastasis. Polo-like kinase 1 (PLK1) has been recognized as a valuable target in cancer treatment due to the prognostic implication of PLK1 in cancer patients and its clinical relevance between the overexpression of PLK1 and the reduced survival rates of several carcinoma patients. Recent studies suggest that several flavonoids, including genistein directly inhibit PLK1 inhibitory activity. Later, we focus on the anticancer effects of genistein through inhibition of PLK1.

Design, synthesis, and evaluation of the antiproliferative activity of hydantoin-derived antiandrogen-genistein conjugates

Androgen receptor (AR) signaling is vital to the viability of all forms of prostate cancer (PCa). With the goal of investigating the effect of simultaneous inhibition and depletion of AR on viability of PCa cells, we designed, synthesized and characterized the bioactivities of bifunctional agents which incorporate the independent cancer killing properties of an antiandrogen and genistein, and the AR downregulation effect of genistein within a single molecular template. We observed that a representative conjugate, 9b, is much more cytotoxic to both LNCaP and DU145 cells relative to the antiandrogen and genistein building blocks as single agents or their combination. Moreover, conjugate 9b more effectively down regulates cellular AR protein levels relative to genistein and induces S phase cell cycle arrest. The promising bioactivities of these conjugates warrant further investigation.

Estrogen receptor modulators genistein, daidzein and ERB-041 inhibit cell migration, invasion, proliferation and sphere formation via modulation of FAK and PI3K/AKT signaling in ovarian cancer

Background

Ovarian cancer is the most lethal gynaecological malignancy. Chemotherapy is the main stay of treatment for metastatic disease, with modest response rates but significant side effects. Therefore, there is a need for alternative therapies that can control the disease while offering good quality of life. Ovarian cancer cells express both estrogen receptor subtypes (ERα and ERβ). There is growing evidence that ERβ is anti-oncogenic. Genistein and daidzein are phytoestrogens found in soybeans and they display higher affinity to bind ERβ. ERB-041 is a potent selective ERβ agonist. In this study, we aimed to investigate the effects of genistein, daidzein and ERB-041 on ovarian cancer.

Methods

Ovarian cancer cell lines were treated with genistein, daidzein and ERB-041 in pharmacological doses. Cell migration, invasion, proliferation, cell cycle arrest, apoptosis and sphere formation were assessed by Transwell migration and invasion assays, XTT assay, focus formation, flow cytometry and sphere formation assay, respectively. Immunoblotting analysis was performed to determine the downstream signaling pathways.

Results

We found that genistein, daidzein and ERB-041 significantly inhibited ovarian cancer cell migration, invasion, proliferation, as well as induced cell cycle arrest and apoptosis. Significantly inhibitory effect on the size and number of sphere formed in genistein, daidzein and ERB-041 treated cells was also demonstrated. Moreover, genistein, daidzein and ERB-041 treatment reduced p-FAK, p-PI3K, p-AKT, p-GSK3β, p21 or cyclin D1 expression in ovarian cancer cells.

Conclusion

Genistein, daidzein and ERB-041 decreased ovarian cancer cell migration, invasion, proliferation and sphere formation, and induced cell cycle arrest and apoptosis with altered FAK and PI3K/AKT/GSK signaling and p21/cyclin D1 expression, suggesting their roles on ovarian cancer cell metastasis, tumorigenesis and stem-like properties and their potential as alternative therapies for ovarian cancer patients.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0559-2) contains supplementary material, which is available to authorized users.

Sensitivity of TP53-Mutated Cancer Cells to the Phytoestrogen Genistein Is Associated With Direct Inhibition of Plk1 Activity

Polo-like kinase 1 (Plk1), a conserved Ser/Thr mitotic kinase, has been identified as a promising target for anticancer drug development because its overexpression is correlated with malignancy. Here, we found that genistein, an isoflavone, inhibits Plk1 kinase activity directly. Previously the mitotic disturbance phenomenon induced by treatment with genistein was not fully explained by its inhibitory effect on EGFR. In kinase profiling assays, it showed selectivity relative to a panel of kinases, including EGFR. Treatment with genistein induced cell death in a concentration-dependent manner in cancer cells from diverse tissue origins, but not in non-transformed cells such as hTERT-RPE or MCF10A cells. We also observed that genistein tended to be more selective against cancer cells with mutations in the TP53 gene. TP53-depeleted LNCaP and NCI-H460 cells using shRNA targeting human TP53 were more sensitive to cell death by treatment of genistein. Furthermore, genistein induced mitotic arrest by inhibiting Plk1 activity and, consequently, led to mitotic catastrophe and apoptosis. These data suggest that genistein may be a promising anticancer drug candidate due to its inhibitory activity against Plk1 as well as EGFR and effectiveness toward cancer cells, especially those with p53-mutation. J. Cell. Physiol. 232: 2818-2828, 2017. © 2016 Wiley Periodicals, Inc.

Genistein: Its role in metabolic diseases and cancer

Genistein is an isoflavone present in soy and is known to have multiple molecular effects, such as the inhibition of inflammation, promotion of apoptosis, and modulation of steroidal hormone receptors and metabolic pathways. Since these molecular effects impact carcinogenesis, cancer propagation, obesity, osteoporosis, and metabolic syndromes, genistein plays an important role in preventing and treating common disorders. The role of genistein has not been adequately evaluated in all these clinical settings. This review summarizes some of the known molecular effects of genistein and its potential role in health maintenance and treatment.

DNA Methylation Targets Influenced by Bisphenol A and/or Genistein Are Associated with Survival Outcomes in Breast Cancer Patients

Early postnatal exposures to Bisphenol A (BPA) and genistein (GEN) have been reported to predispose for and against mammary cancer, respectively, in adult rats. Since the changes in cancer susceptibility occurs in the absence of the original chemical exposure, we have investigated the potential of epigenetics to account for these changes. DNA methylation studies reveal that prepubertal BPA exposure alters signaling pathways that contribute to carcinogenesis. Prepubertal exposure to GEN and BPA + GEN revealed pathways involved in maintenance of cellular function, indicating that the presence of GEN either reduces or counters some of the alterations caused by the carcinogenic properties of BPA. We subsequently evaluated the potential of epigenetic changes in the rat mammary tissues to predict survival in breast cancer patients via the Cancer Genomic Atlas (TCGA). We identified 12 genes that showed strong predictive values for long-term survival in estrogen receptor positive patients. Importantly, two genes associated with improved long term survival, HPSE and RPS9, were identified to be hypomethylated in mammary glands of rats exposed prepuberally to GEN or to GEN + BPA respectively, reinforcing the suggested cancer suppressive properties of GEN.

Inhibition of CDK4/6 as a novel therapeutic option for neuroblastoma

Background

Neuroblastoma is a neural crest-derived tumor and is the most common cancer in children less than 1 year of age. We hypothesized that aberrations in genes that control the cell cycle could play an important role in the pathogenesis of neuroblastoma and could provide a tractable therapeutic target.

Methods

In this study, we screened 131 genes involved in cell cycle regulation at different levels by analyzing the effect of siRNA-mediated gene silencing on the proliferation of neuroblastoma cells.

Results

Marked reductions in neuroblastoma cellular proliferation were recorded after knockdown of CCND1 or PLK1. We next showed that pharmacological inhibition of cyclin D1 dependent kinases 4/6 (CDK4/6) with PD 0332991 (palbociclib) reduced the growth of neuroblastoma cell lines, induced G1 cell cycle arrest, and inhibited the cyclin D1-Rb pathway.

Conclusion

Selective inhibition of CDK4/6 using palbociclib may provide a new therapeutic option for treating neuroblastoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-015-0224-y) contains supplementary material, which is available to authorized users.

Antiproliferative effects of n-butyl-β-D-fructofuranoside from Kangaisan on Bel-7402 cells

Aims:

Kangaisan is a powdered compound prescription of Traditional Chinese Medicine which has been used in cancers for many years in Hubei province, China. The purpose of this study was to investigate the antitumor effects of Kangaisan and screen bioactive components.

Materials and Methods:

3-(4,5-Dimethythiazol-2-yl)-2,5 diphenyl-tetrazolium bromide (MTT) assay, flow cytometry, DNA (Deoxyribonucleic acid) fragmentation assay, Western blot, and real time-polymerase chain reaction were used to investigate the antiproliferation effect of n-butyl-β-D-fructofuranoside on Bel-7402 cells.

Statistical Analysis:

All experiments were performed in triplicate and the results were expressed as mean ± standard deviation. Statistical analysis was performed with analysis of variance using Origin 8.0 software.

Results:

It was illustrated that treatment of Bel-7402 cells with various concentrations of n-butyl-β-D-fructofuranoside resulted in growth inhibition in both a dose-dependent and time-dependent manner. The arrest of G0/G1 phase was also induced (P < 0.05). The increasing of sub-G1 cell population indicated the apoplectic characteristic (P < 0.05). Furthermore, the emerging of DNA fragmentation and the increase of Bax/Bcl-2 ratio and p53 expression suggested the possible mitochondrial apoptotic pathway (P < 0.05).

Conclusions:

The results illustrate that Kangaisan showed anticancer effects and n-butyl-β-D-fructofuranoside extracted from Kangaisan can suppress Bel-7402 cells via interfering cell cycle and by inducing apoptosis.

Genistein induces G2/M arrest in gastric cancer cells by increasing the tumor suppressor PTEN expression

Genistein, a major isoflavone found in soybeans, exhibits anticarcinogenic properties. The inhibitory effect of genistein on cell proliferation is associated with G2/M cell cycle arrest and inhibition of cdc2 activities. Here we assessed the role of PTEN in regulation of genistein-mediated G2/M cell cycle arrest in the gastric cancer cell lines (SGC-7901 and BGC-823). After 24 h following treatment, genistein induced a concentration-dependent accumulation of cells in the G2/M phase of the cell cycle. The sustained G2/M arrest by genistein in SGC-7901 and BGC-823 cells is associated with increased phospho-cdc2 (Tyr15) and decreased cdc2 protein. Genistein treatment increased Wee1 levels and decreased phospho-Wee1 (Ser 642). Moreover, genistein substantially decreased the Ser473 and Thr308 phosphorylation of Akt and upregulated PTEN expression. Downregulation of PTEN by siRNA in genistein-treated cells increased phospho-Wee1 (Ser642), whereas decreased phospho-Cdc2 (Tyr15), resulting in decreased the G2/M cell cycle arrest. Therefore, induction of G2/M cell cycle arrest by genistein involved upregulation of PTEN.

Pleiotropic effects of genistein in metabolic, inflammatory, and malignant diseases

Genistein is a soy-derived biologically active isoflavone that exhibits diverse health-promoting effects. An increasing body of evidence shows that genistein influences lipid homeostasis and insulin resistance, counteracts inflammatory cytokines, and possesses antidiabetic properties. Genistein also impedes cancer progression by promoting apoptosis, inducing cell cycle arrest, modulating intracellular signaling pathways, and inhibiting angiogenesis and metastasis of neoplastic cells. This review summarizes the pleiotropic functions of genistein in common health disorders such as metabolic syndrome, chronic inflammatory diseases, and cancer. In the current era of uncontrolled health expenditure, a focus on the clinical development of nutritional agents with the capacity to prevent a variety of common health disorders is needed. As a micronutrient that exerts multifaceted effects ranging from antidiabetic to anticarcinogenic functions, genistein should be clinically developed further for use in the prevention and treatment of a variety of health disorders.

Genistein-induced G2/M cell cycle arrest of human intestinal colon cancer Caco-2 cells is associated with Cyclin B1 and Chk2 down-regulation

Genistein is an isoflavonic phyto-oestrogen contained in soya beans. It is thought to display anti-cancer effects. This study was designed to investigate its effect on human intestinal colon cancer Caco-2 cells. MTT assay, flow cytometric analysis and western blotting were used to investigate the effect of genistein on cell proliferation, cell cycle progression and protein alterations of selected cell cycle-related proteins in Caco-2 cells. Our results showed that genistein and daidzein significantly suppressed cell proliferation. Genistein treatment was demonstrated to modulate cell cycle distribution through accumulation of cells at G2/M phase, with a significant decreasing effect of Cyclin B1 and Serine/threonine-protein kinase 2 (Chk2) proteins expression. However, daidzein did not alter the cell cycle progression in Caco-2 cells. All these observation strongly indicate that genistein has anti-proliferative effect in human intestinal colon cancer Caco-2 cells through the down-regulation of cell cycle check point proteins, Cyclin B1 and Chk2.

Type 1 IFN inhibits the growth factor deprived apoptosis of cultured human aortic endothelial cells and protects the cells from chemically induced oxidative cytotoxicity

It has been shown that the genesis of atherosclerotic lesions is resulted from the injury of vascular endothelial cells and the cell damage is triggered by oxygen radicals generated from various tissues. Human vascular endothelial cells can survive and proliferate depending on growth factors such as VEGF or basic FGF and are induced apoptosis by the deprivation of growth factor or serum. It was found that type 1 IFN inhibits the growth factor deprived cell death of human aortic endothelial cells (HAEC) and protects the cells from chemically induced oxidative cytotoxicity. The anti-apoptotic effects of type 1 IFN were certified by flow cytometry using annexin-V-FITC/PI double staining and cell cycle analysis, fluorescence microscopy using Hoechst33342 and PI, colorimetric assay for caspase-3 activity, p53 and bax mRNA expressions, and cell counts. It was considered that IFN-β inhibits the executive late stage apoptosis from the results of annexin-V-FITC/PI double staining and the inhibition of caspase-3 activity, and that the anti-apoptotic effect might be owing to the direct inhibition of the apoptotic pathway mediated by p53 from the transient down-regulation of bax mRNA expression. Whereas, type 1 IFN protected the cells from the oxidative cytotoxicity induced by tertiary butylhydroperoxide (TBH) under the presence of Ca(2+). The effects of IFN-β is more potent inhibitor of cell death than IFN-α. These results indicate that type 1 IFN, especially IFN-β may be useful for the diseases with vascular endothelium damage such as atherosclerosis or restenosis after angioplasty as a medical treatment or a prophylactic.

Genistein inhibits estradiol- and environmental endocrine disruptor-induced growth effects on neuroblastoma cells in vitro

The aim of this study was to examine the effect of genistein on human neuroblastoma cell proliferation induced by two common environmental endocrine disruptors, bisphenol A (BPA) and Di-2-ethylhexyl phthalate (DEHP), and to investigate its underlying mechanism. SK-N-SH human neuroblastoma cells were treated with E₂ (1 ng/ml), BPA (2 μg/ml) or DEHP (100 μM), with or without genistein (12.5 μM) in vitro. The number of viable cells was detected with an absorbance reader after 0, 24, 48 or 72 h treatment. The percentage of cells in different phases, and expression of Akt and its phosphorylation levels were also assessed by flow cytometry and western blot analysis at 72 h, respectively. The BPA and DEHP groups had a 30% higher number of viable cells compared to the non-treated group at 48 h (P<0.001). However, the cell numbers did not increase significantly in the groups with additional treatment with genistein (P>0.05 vs. control) and the same trend was observed at 72 h. The expression of phospho-Akt protein was increased in the groups treated with BPA or DEHP compared to the control group at 72 h (P<0.05), while no significant elevation in the expression of phospho-Akt was observed (P>0.05) in genistein-treated groups. Cells were arrested at the G₂/M phase by genistein. Similar effects were observed in the E₂ group with or without genistein treatment. Akt protein expression had no significant change among all the groups (P>0.05). In conclusion, estradiol- or environmental endocrine disruptor-induced proliferation of human neuroblastoma cells is effectively abolished by genistein, likely in a cell cycle- and Akt pathway-dependent manner.

Reovirus uses multiple endocytic pathways for cell entry

Entry of reovirus virions has been well studied in several tissue culture systems. After attachment to junctional adhesion molecule A (JAM-A), virions undergo clathrin-mediated endocytosis followed by proteolytic disassembly of the capsid and penetration to the cytoplasm. However, during in vivo infection of the intestinal tract, and likely in the tumor microenvironment, capsid proteolysis (uncoating) is initiated extracellularly. We used multiple approaches to determine if uncoated reovirus particles, called intermediate subviral particles (ISVPs), enter cells by directly penetrating the limiting membrane or if they take advantage of endocytic pathways to establish productive infection. We found that entry and infection by reovirus ISVPs was inhibited by dynasore, an inhibitor of dynamin-dependent endocytosis, as well as by genistein and dominant-negative caveolin-1, which block caveolar endocytosis. Inhibition of caveolar endocytosis also reduced infection by reovirus virions. Extraction of membrane cholesterol with methyl-β-cyclodextrin inhibited infection by virions but had no effect when infection was initiated with ISVPs. We found this pathway to be independent of both clathrin and caveolin. Together, these data suggest that reovirus virions can use both dynamin-dependent and dynamin-independent endocytic pathways during cell entry, and they reveal that reovirus ISVPs can take advantage of caveolar endocytosis to establish productive infection.

Apoptotic effects of genistein, biochanin-A and apigenin on LNCaP and PC-3 cells by p21 through transcriptional inhibition of polo-like kinase-1

Natural isoflavones and flavones are important dietary factors for prostate cancer prevention. We investigated the molecular mechanism of these compounds (genistein, biochanin-A and apigenin) in PC-3 (hormone-independent/p53 mutant type) and LNCaP (hormone-dependent/p53 wild type) prostate cancer cells. A cell growth rate and apoptotic activities were analyzed in different concentrations and exposure time to evaluate the antitumor activities of genistein, biochanin-A and apigenin. The real time PCR and Western blot analysis were performed to investigate whether the molecular mechanism of these compounds are involving the p21 and PLK-1 pathway. Apoptosis of prostate cancer cells was associated with p21 up-regulation and PLK-1 suppression. Exposure of genistein, biochanin-A and apigenin on LNCaP and PC-3 prostate cancer cells resulted in same pattern of cell cycle arrest and apoptosis. The inhibition effect for cell proliferation was slightly greater in LNCaP than PC-3 cells. In conclusion, flavonoids treatment induces up-regulation of p21 expression, and p21 inhibits transcription of PLK-1, which promotes apoptosis of cancer cells.

Dietary phytochemicals, HDAC inhibition, and DNA damage/repair defects in cancer cells

Genomic instability is a common feature of cancer etiology. This provides an avenue for therapeutic intervention, since cancer cells are more susceptible than normal cells to DNA damaging agents. However, there is growing evidence that the epigenetic mechanisms that impact DNA methylation and histone status also contribute to genomic instability. The DNA damage response, for example, is modulated by the acetylation status of histone and non-histone proteins, and by the opposing activities of histone acetyltransferase and histone deacetylase (HDAC) enzymes. Many HDACs overexpressed in cancer cells have been implicated in protecting such cells from genotoxic insults. Thus, HDAC inhibitors, in addition to unsilencing tumor suppressor genes, also can silence DNA repair pathways, inactivate non-histone proteins that are required for DNA stability, and induce reactive oxygen species and DNA double-strand breaks. This review summarizes how dietary phytochemicals that affect the epigenome also can trigger DNA damage and repair mechanisms. Where such data is available, examples are cited from studies in vitro and in vivo of polyphenols, organosulfur/organoselenium compounds, indoles, sesquiterpene lactones, and miscellaneous agents such as anacardic acid. Finally, by virtue of their genetic and epigenetic mechanisms, cancer chemopreventive agents are being redefined as chemo- or radio-sensitizers. A sustained DNA damage response coupled with insufficient repair may be a pivotal mechanism for apoptosis induction in cancer cells exposed to dietary phytochemicals. Future research, including appropriate clinical investigation, should clarify these emerging concepts in the context of both genetic and epigenetic mechanisms dysregulated in cancer, and the pros and cons of specific dietary intervention strategies.

Src kinase mediates productive endocytic sorting of reovirus during cell entry

Reovirus cell entry is initiated by viral attachment to cell surface glycans and junctional adhesion molecule A. Following receptor engagement, reovirus is internalized into cells by receptor-mediated endocytosis using a process dependent on β1 integrin. Endocytosed virions undergo stepwise disassembly catalyzed by cathepsin proteases, followed by endosomal membrane penetration and delivery of transcriptionally active core particles into the cytoplasm. Cellular factors that mediate reovirus endocytosis are poorly defined. We found that both genistein, a broad-spectrum tyrosine kinase inhibitor, and PP2, a specific Src-family kinase inhibitor, diminish reovirus infectivity by blocking a cell entry step. Although neither inhibitor impedes internalization of reovirus virions, both inhibitors target virions to lysosomes. Reovirus colocalizes with Src during cell entry, and reovirus infection induces phosphorylation of Src at the activation residue, tyrosine 416. Diminished Src expression by RNA interference reduces reovirus infectivity, suggesting that Src is required for efficient reovirus entry. Collectively, these data provide evidence that Src kinase is an important mediator of signaling events that regulate the appropriate sorting of reovirus particles in the endocytic pathway for disassembly and cell entry.

N-(4-Hydroxyphenyl) Retinamide Potentiated Anti-tumor Efficacy of Genistein in Human Ewing's Sarcoma Xenografts

Background

Ewing’s sarcoma is a pediatric tumor that mainly occurs in soft tissues and bones. New therapeutic strategies are urgently needed for treatment of Ewing’s sarcoma. We examined for the first time the efficacy of N-(4-hydroxyphenyl) retinamide (4-HPR) and genistein (GST) alone and also in combination for controlling growth of human Ewing’s sarcoma SK-N-MC and RD-ES xenografts.

Methods

Efficacy of combination therapy was evaluated using histopathological parameters. Molecular mechanisms of combination therapy were detected using Western blotting and immunofluorescence microscopy.

Results

Histopathological examination of tumor sections showed that control group maintained characteristic growth of tumors, 4-HPR alone inhibited proliferation of tumor cells, GST alone induced apoptosis to some extent, and combination of 4-HPR and GST significantly induced apoptosis in both Ewing’s sarcoma xenografts. Time-dependent reductions in body weight, tumor volume, and tumor weight were also found. Combination therapy increased Bax : Bcl-2 ratio to trigger mitochondrial release of Smac/Diablo into the cytosol to downregulate the baculovirus inhibitor-of-apoptosis repeat containing (BIRC) proteins such as BIRC-2 and BIRC-3 and thereby promote apoptosis. Activation of caspase-3 and mitochondrial release of apoptosis-inducing factor (AIF) occurred in course of apoptosis. Downregulation of the survival factor NF-κB and the angiogenic factors VEGF and FGF2 and increase in caspase-3 activity controlled tumor growth. In situ immunofluorescent labelings showed overexpression of calpain, caspase-12 and caspase-3, and AIF in xenografts, indicating induction of cysteine proteases and AIF for apoptosis.

Conclusions

Results revealed that combination of 4-HPR and GST could be highly effective treatment for inhibiting Ewing’s sarcomas in vivo.

Inhibition of cancer cell invasion and metastasis by genistein

Genistein is a small, biologically active flavonoid that is found in high amounts in soy. This important compound possesses a wide variety of biological activities, but it is best known for its ability to inhibit cancer progression. In particular, genistein has emerged as an important inhibitor of cancer metastasis. Consumption of genistein in the diet has been linked to decreased rates of metastatic cancer in a number of population-based studies. Extensive investigations have been performed to determine the molecular mechanisms underlying genistein's antimetastatic activity, with results indicating that this small molecule has significant inhibitory activity at nearly every step of the metastatic cascade. Reports have demonstrated that, at high concentrations, genistein can inhibit several proteins involved with primary tumor growth and apoptosis, including the cyclin class of cell cycle regulators and the Akt family of proteins. At lower concentrations that are similar to those achieved through dietary consumption, genistein can inhibit the prometastatic processes of cancer cell detachment, migration, and invasion through a variety of mechanisms, including the transforming growth factor (TGF)-beta signaling pathway. Several in vitro findings have been corroborated in both in vivo animal studies and in early-phase human clinical trials, demonstrating that genistein can both inhibit human cancer metastasis and also modulate markers of metastatic potential in humans, respectively. Herein, we discuss the variety of mechanisms by which genistein regulates individual steps of the metastatic cascade and highlight the potential of this natural product as a promising therapeutic inhibitor of metastasis.

Pseudomonas aeruginosa exotoxin A reduces chemoresistance of oral squamous carcinoma cell via inhibition of heat shock proteins 70 (HSP70)

PURPOSE

Oral squamous carcinoma (OSCC) cells exhibit resistance to chemotherapeutic agent-mediated apoptosis in the late stage of malignancy. Increased levels of heat shock proteins 70 (HSP70) in cancer cells are known to confer resistance to apoptosis. Since recent advances in the understanding of bacterial toxins have produced new strategies for the treatment of cancers, we investigated the effect of Pseudomonas aeruginosa exotoxin A (PEA) on HSP70 expression and induction of apoptosis in chemoresistant OSCC cell line (YD-9).

MATERIALS AND METHODS

The apoptotic effect of PEA on chemoresistant YD-9 cells was confirmed by MTT, Hoechst and TUNEL stains, DNA electrophoresis, and Western blot analysis.

RESULTS

While YD-9 cells showed high resistance to chemotherapeutic agents such as etoposide and 5-fluorouraci (5-FU), HSP70 antisense oligonucelotides sensitized chemoresistant YD-9 cells to etoposide and 5-FU. On the other hand, PEA significantly decreased the viability of YD-9 cells by deteriorating the HSP70-relating protecting system through inhibition of HSP70 expression and inducing apoptosis in YD-9 cells. Apoptotic manifestations were evidenced by changes in nuclear morphology, generation of DNA fragmentation, and activation of caspases. While p53, p21, and E2F-1 were upregulated, cdk2 and cyclin B were downregulated by PEA treatment, suggesting that PEA caused cell cycle arrest at the G2/M checkpoint.

CONCLUSION

Therefore, these results indicate that PEA reduced the chemoresistance through inhibition of HSP70 expression and also induced apoptosis in chemoresistant YD-9 cells.

Modulating polo-like kinase 1 as a means for cancer chemoprevention

Naturally occurring agents have always been appreciated for their medicinal value for both their chemopreventive and therapeutic effects against cancer. In fact, the majority of the drugs we use today, including the anti-cancer agents, were originally derived from natural compounds, either in their native form or modified to enhance their bioavailability or specificity. It is believed that for maximum effectiveness, it will useful to design novel target-based agents for chemoprevention as well as the treatment of cancer. Recent studies have shown that the serine/threonine kinase polo-like kinase (Plk) 1 is widely overexpressed in a variety of cancers and is being increasingly appreciated as a target for cancer management. Additionally, several chemopreventive agents have been shown to inhibit Plk1 in cancer cells. In this review, we will discuss if Plk1 could also be a target for designing novel strategies for cancer chemoprevention.

Growth inhibition, morphology change, and cell cycle alterations in NFBD1-depleted human esophageal cancer cells

NFBD1/MDC1 is a large nuclear protein mainly participating in DNA damage response, indicating its therapeutic potential as a radio-/chemosensitizer target in cancer field. Esophageal cancer ranks among one of the most frequent cause of cancer death in the world. In this study, we used three representative esophageal cancer cell lines to investigate the effects of NFBD1 silencing on cell proliferation, cell morphology, and cell cycle distribution. Synthetic small interfering RNA (siRNA) duplexes against NFBD1 were introduced into three esophageal cancer cell lines, which subsequently resulted in a significant inhibition in NFBD1 expression in the cells. Our results have shown that a targeted siRNA depletion of NFBD1 resulted in a significant growth inhibition, morphology change, and cell cycle alterations in esophageal cancer cells. Furthermore, NFBD1 depletion also sensitized all the three esophageal cancer cell lines to chemotherapeutic agents including adriamycin and cisplatin. Taken together, our study strongly suggested that NFBD1 may serve as a potential therapeutic target in human esophageal cancer.

Down-regulation of Bcl-2 and Akt induced by combination of photoactivated hypericin and genistein in human breast cancer cells

Presented experiment considers combination of genistein and photodynamic therapy with hypericin with a view to achieve higher therapeutic outcome in human breast adenocarcinoma cell lines MCF-7 and MDA-MB-231, both identified in our conditions as photodynamic therapy resistant. Since genistein is known to suppress Bcl-2 expression, we predicted that photodynamic therapy with hypericin might benefit from mutual therapeutic combination. In line with our expectations, combined treatment led to down-regulation of Bcl-2 and up-regulation of Bax in both cell lines as well as to suppression of Akt and Erk1/2 phosphorylation induced by photoactivated hypericin in MCF-7 cells. Although Akt and Erk1/2 phosphorylation was not stimulated by photodynamic therapy with hypericin in MDA-MB-231 cells, it was effectively suppressed in combination. Variations in cell death signaling favoring apoptosis were indeed accompanied by cell cycle arrest in G(2)/M-phase, activation of caspase-7, PARP cleavage and increased occurrence of cells with apoptotic morphology of nucleus. All these events corresponded with suppression of proliferation and significantly lowered clonogenic ability of treated cells. In conclusion, our results indicate that pre-treatment with tyrosine kinase inhibitor genistein may significantly improve the effectiveness of photodynamic therapy with hypericin in MCF-7 and MDA-MB-231 breast cancer cells.

Synergistic efficacy of sorafenib and genistein in growth inhibition by down regulating angiogenic and survival factors and increasing apoptosis through upregulation of p53 and p21 in malignant neuroblastoma cells having N-Myc amplification or non-amplification

Neuroblastoma is an extracranial, solid, and heterogeneous malignancy in children. The conventional therapeutic modalities are mostly ineffective and thus new therapeutic strategies for malignant neuroblastoma are urgently warranted. We examined the synergistic efficacy of combination of sorafenib (SF) and genistein (GST) in human malignant neuroblastoma SK-N-DZ (N-Myc amplified) and SH-SY5Y (N-Myc non-amplified) cell lines. MTT assay showed dose-dependent decrease in cell viability and the combination therapy more prominently inhibited the cell proliferation in both cell lines than either treatment alone. Apoptosis was confirmed morphologically by Wright staining. Flow cytometric analysis of cell cycle phase distribution and Annexin V-FITC/PI staining showed increase in subG1 DNA content and early apoptosis, respectively, after treatment with the combination of drugs. Apoptosis was further confirmed by scanning electron microscopy. Combination therapy showed activation of caspase-8, cleavage of Bid to tBid, increase in p53 and p21 expression, down regulation of anti-apoptotic Mcl-1, and increase in Bax:Bcl-2 ratio to trigger apoptosis. Down regulation of MDR, hTERT, N-Myc, VEGF, FGF-2, NF-κB, p-Akt, and c-IAP2 indicated suppression of angiogenic and survival pathways. Mitochondrial release of cytochrome c and Smac into cytosol indicated involvement of mitochondia in apoptosis. Increases in proteolytic activities of calpain and caspase-3 were also confirmed. Our results suggested that combination of SF and GST inhibited angiogenic and survival factors and increased apoptosis via receptor and mitochondria mediated pathways in both neuroblastoma SK-N-DZ and SH-SY5Y cell lines. Thus, this combination of drugs could be a potential therapeutic strategy against human malignant neuroblastoma cells having N-Myc amplification or non-amplification.

LMO4 is an essential mediator of ErbB2/HER2/Neu-induced breast cancer cell cycle progression

ErbB2/HER2/Neu-overexpressing breast cancers are characterized by poor survival due to high proliferation and metastasis rates and identifying downstream targets of ErbB2 should facilitate developing novel therapies for this disease. Gene expression profiling revealed the transcriptional regulator LIM-only protein 4 [LMO4] is upregulated during ErbB2-induced mouse mammary gland tumorigenesis. While LMO4 is frequently overexpressed in breast cancer and LMO4-overexpressing mice develop mammary epithelial tumors, the mechanisms involved are unknown. Herein, we report that LMO4 is a downstream target of ErbB2 and PI3K in ErbB2-dependent breast cancer cells. Furthermore, LMO4 silencing reduces proliferation of these cells, inducing a G2/M arrest that was associated with decreased cullin-3, an E3-ubiquitin ligase component important for mitosis. Loss of LMO4 subsequently results in reduced Cyclin D1 and Cyclin E. Further supporting a role for LMO4 in modulating proliferation by regulating cullin-3 expression, we found that LMO4 expression oscillates throughout the cell cycle with maximum expression occurring during G2/M and these changes precede oscillations in cullin-3 levels. LMO4 levels are also highest in high grade/less differentiated breast cancers, which are characteristically highly proliferative. We conclude that LMO4 is a novel cell cycle regulator with a key role in mediating ErbB2-induced proliferation, a hallmark of ErbB2-positive disease.

Genistein inhibition of topoisomerase IIalpha expression participated by Sp1 and Sp3 in HeLa cell

Genistein (4′, 5, 7-trihydroxyisoflavone) is an isoflavone compound obtained from plants that has potential applications in cancer therapy. However, the molecular mechanism of the action of genistein on cancer cell apoptosis is not well known. In this study, we investigated the effect of genistein on topoisomerase II-α (Topo IIα), an important protein involved in the processes of DNA replication and cell proliferation. The results revealed that inhibition of Topo IIα expression through the regulation of Specificity protein 1 and Specificity protein 3 may be one of the reasons for genistein’s induction of HeLa cell apoptosis.

N-Myc down regulation induced differentiation, early cell cycle exit, and apoptosis in human malignant neuroblastoma cells having wild type or mutant p53

Neuroblastomas, which mostly occur in children, are aggressive metastatic tumors of the sympathetic nervous system. The failure of the previous therapeutic regimens to target multiple components of N-Myc pathway resulted in poor prognosis. The present study investigated the efficacy of the combination of N-(4-hydroxyphenyl) retinamide (4-HPR, 0.5 microM) and genistein (GST, 25 microM) to control the growth of human neuroblastoma cells (SH-SY5Y and SK-N-BE2) harboring divergent molecular attributes. Combination of 4-HPR and GST down regulated N-Myc, Notch-1, and Id2 to induce neuronal differentiation. Transition to neuronal phenotype was accompanied by increase in expression of e-cadherin. Induction of neuronal differentiation was associated with decreased expression of hTERT, PCNA, survivin, and fibronectin. This is the first report that combination of 4-HPR and GST mediated reactivation of multiple tumor suppressors (p53, p21, Rb, and PTEN) for early cell cycle exit (due to G1/S phase arrest) in neuroblastoma cells. Reactivation of tumor suppressor(s) repressed N-Myc driven growth factor mediated angiogenic and invasive pathways (VEGF, b-FGF, MMP-2, and MMP-9) in neuroblastoma. Repression of angiogenic factors led to the blockade of components of mitogenic pathways [phospho-Akt (Thr 308), p65 NF-kappaB, and p42/44 Erk 1/2]. Taken together, the combination of 4-HPR and GST effectively blocked survival, mitogenic, and angiogenic pathways and activated proteases for apoptosis in neuroblastoma cells. These results suggested that combination of 4-HPR and GST could be effective for controlling the growth of heterogeneous human neuroblastoma cell populations.

Bcl-2 inhibitor HA14-1 and genistein together adeptly down regulated survival factors and activated cysteine proteases for apoptosis in human malignant neuroblastoma SK-N-BE2 and SH-SY5Y cells

Neuroblastoma is a pediatric extracranial tumor and a major cause of death in children under age 2. Conventional therapy shows inefficacy in most cases and thus development of new therapeutic strategies is urgently needed. We explored the efficacy of combination of the small molecule Bcl-2 inhibitor HA14-1 (HA) and the isoflavonoid genistein (GST) in human malignant neuroblastoma SK-N-BE2 and SH-SY5Y cells. Combination of 10 microM HA and 250 microM GST was optimal for SK-N-BE2 cells and combination of 5 microM HA and 100 microM GST was optimal for SH-SY5Y cells for induction of apoptosis. Phase-contrast microscopy and Wright staining showed morphological features of apoptosis. Cell cycle analysis and Annexin V-FITC/PI binding assay showed that combination of HA and GST was more effective in inducing apoptosis in both cell lines than either HA or GST alone. Western blotting showed that combination of HA and GST caused upregulation of Bax and down regulation of Bcl-2 resulting in increased Bax:Bcl-2 ratio and mitochondrial release of cytochrome c, Smac, and AIF. Down regulation of survival factors such as NF-kappaB, N-Myc, and survivin promoted apoptosis. Activation of caspase-8, calpain, and caspase-3 occurred in course of apoptosis. Increased calpain and caspase-3 activities were confirmed in the degradation of alpha-spectrin to 145 kD spectrin break down product (SBDP) and 120 kD SBDP, respectively. Thus, combination of HA and GST could serve as a promising therapeutic strategy for increasing apoptosis in different human malignant neuroblastoma cells.

The phytoestrogen genistein affects zebrafish development through two different pathways

BACKGROUND

Endocrine disrupting chemicals are widely distributed in the environment and derive from many different human activities or can also be natural products synthesized by plants or microorganisms. The phytoestrogen, genistein (4', 5, 7-trihydroxy-isoflavone), is a naturally occurring compound found in soy products. Genistein has been the subject of numerous studies because of its known estrogenic activity.

METHODOLOGY/PRINCIPAL FINDINGS

We report that genistein exposure of zebrafish embryos induces apoptosis, mainly in the hindbrain and the anterior spinal cord. Timing experiments demonstrate that apoptosis is induced during a precise developmental window. Since adding ICI 182,780, an ER antagonist, does not rescue the genistein-induced apoptosis and since there is no synergistic effect between genistein and estradiol, we conclude that this apoptotic effect elicited by genistein is estrogen-receptors independent. However, we show in vitro, that genistein binds and activates the three zebrafish estrogen receptors ERalpha, ERbeta-A and ERbeta-B. Furthermore using transgenic ERE-Luciferase fish we show that genistein is able to activate the estrogen pathway in vivo during larval stages. Finally we show that genistein is able to induce ectopic expression of the aromatase-B gene in an ER-dependent manner in the anterior brain in pattern highly similar to the one resulting from estrogen treatment at low concentration.

CONCLUSION/SIGNIFICANCE

TAKEN TOGETHER THESE RESULTS INDICATE THAT GENISTEIN ACTS THROUGH AT LEAST TWO DIFFERENT PATHWAYS IN ZEBRAFISH EMBRYOS: (i) it induces apoptosis in an ER-independent manner and (ii) it regulates aromatase-B expression in the brain in an ER-dependent manner. Our results thus highlight the multiplicity of possible actions of phytoestrogens, such as genistein. This suggests that the use of standardized endpoints to study the effect of a given compound, even when this compound has well known targets, may carry the risk of overlooking interesting effects of this compound.

Apoptotic activity of genistein on human lung adenocarcinoma SPC-A-1 cells and preliminary exploration of its mechanisms using microarray

Soy isoflavone genistein is active against certain solid malignancies, but its direct effect on lung adenocarcinoma and its mechanisms of action remain to be elucidated. In the present study, using the human lung adenocarcinoma cell line SPC-A-1, we found that genistein decreased SPC-A-1 cell viability in both a dose and time dependent manner. Flow cytometry analysis revealed that genistein significantly induced arrest of SPC-A-1 cells at the G2/M phase of the cell cycle. Furthermore, through DNA fragmentation and TUNEL assays, we demonstrated that the addition of genistein led to SPC-A-1 apoptosis in both a dose and time dependent manner. Finally, the apoptosis pathway-related gene expression profile affected by genistein was investigated using the oligonucleotide microarray method. The result showed that the expression profile of 20 genes (ratio of genistein group/control group >2 or <0.5) related to the apoptotic pathways changed. These genes, mainly consisting of the Bcl-2 family and TNF ligand and receptor family, are involved in regulation of the apoptosis process.