Genistein reduces NF-kappa B in T lymphoma cells via a caspase-mediated cleavage of I kappa B alpha

Engineered nanoparticles for imaging and drug delivery in colorectal cancer

Colorectal cancer (CRC) is one of the deadliest diseases worldwide due to a lack of early detection methods and appropriate drug delivery strategies. Conventional imaging techniques cannot accurately distinguish benign from malignant tissue, leading to frequent misdiagnosis or diagnosis at late stages of the disease. Novel screening tools with improved accuracy and diagnostic precision are thus required to reduce the mortality burden of this malignancy. Additionally, current therapeutic strategies, including radio- and chemotherapies carry adverse side effects and are limited by the development of drug resistance. Recent advances in nanotechnology have rendered it an attractive approach for designing novel clinical solutions for CRC. Nanoparticle-based formulations could assist early tumor detection and help to overcome the limitations of conventional therapies including poor aqueous solubility, nonspecific biodistribution and limited bioavailability. In this review, we shed light on various types of nanoparticles used for diagnosis and drug delivery in CRC. In addition, we will explore how these nanoparticles can improve diagnostic accuracy and promote selective drug targeting to tumor sites with increased efficiency and reduced cytotoxicity against healthy colon tissue.

Recent Advances in Characterizing Natural Products that Regulate Autophagy

Autophagy, an intricate response to nutrient deprivation, pathogen infection, Endoplasmic Reticulum (ER)-stress and drugs, is crucial for the homeostatic maintenance in living cells. This highly regulated, multistep process has been involved in several diseases including cardiovascular and neurodegenerative diseases, especially in cancer. It can function as either a promoter or a suppressor in cancer, which underlines the potential utility as a therapeutic target. In recent years, increasing evidence has suggested that many natural products could modulate autophagy through diverse signaling pathways, either inducing or inhibiting. In this review, we briefly introduce autophagy and systematically describe several classes of natural products that implicated autophagy modulation. These compounds are of great interest for their potential activity against many types of cancer, such as ovarian, breast, cervical, pancreatic, and so on, hoping to provide valuable information for the development of cancer treatments based on autophagy.

RNA Expression Profile and Alternative Splicing Signatures of Genistein-Treated Breeder Hens Revealed by Hepatic Transcriptomic Analysis

Little information has been available about the influence of dietary genistein (GEN) on hepatic transcriptome of laying broiler breeder (LBB) hens. The study is aimed at broadening the understanding of RNA expression profiles and alternative splicing (AS) signatures of GEN-treated breeder hens and thereby improving laying performance and immune function of hens during the late egg-laying period. 720 LBB hens were randomly allocated into three groups with supplemental dietary GEN doses (0, 40 mg/kg, and 400 mg/kg). Each treatment has 8 replicates of 30 birds. Dietary GEN enhanced the antioxidative capability of livers, along with the increased activities of glutathione peroxidase and catalase. Furthermore, it improved lipid metabolic status and apoptotic process in the liver of hens. 40 mg/kg dietary GEN had the better effects on improving immune function and laying performance. However, transcriptome data indicated that 400 mg/kg dietary GEN did negative regulation of hormone biosynthetic process. Also, it upregulated the expressions of EDA2R and CYR61 by the Cis regulation of neighbouring genes (lncRNA_XLOC_018890 and XLOC_024242), which might activate NF-κB and immune-related signaling pathway. Furthermore, dietary GEN induced AS events in the liver, which also enriched into immune and metabolic process. Therefore, the application of 40 mg/kg GEN in the diet of breeder hens during the late egg-laying period can improve lipid metabolism and immune function. We need to pay attention to the side-effects of high-dose GEN on the immune function.

Androgen receptor and soy isoflavones in prostate cancer

Androgens and androgen receptor (AR) play a critical role not only in normal prostate development, but also in prostate cancer. For that reason, androgen deprivation therapy (ADT) is the primary treatment for prostate cancer. However, the majority of patients develop castration-resistant prostate cancer, which eventually leads to mortality. Novel therapeutic approaches, including dietary changes, have been explored. Soy isoflavones have become a focus of interest because of their positive health benefits on numerous diseases, particularly hormone-related cancers, including prostate and breast cancers. An important strategy for the prevention and/or treatment of prostate cancer might thus be the action of soy isoflavones on the AR signaling pathway. The current review article provides a detailed overview of the anticancer potential of soy isoflavones (genistein, daidzein and glycitein), as mediated by their effect on AR.

Genistein promotes ionizing radiation-induced cell death by reducing cytoplasmic Bcl-xL levels in non-small cell lung cancer

Genistein (GEN) has been previously reported to enhance the radiosensitivity of cancer cells; however, the detailed mechanisms remain unclear. Here, we report that GEN treatment inhibits the cytoplasmic distribution of Bcl-xL and increases nuclear Bcl-xL in non-small cell lung cancer (NSCLC). Interestingly, our in vitro data show that ionizing radiation IR treatment significantly increases IR-induced DNA damage and apoptosis in a low cytoplasmic Bcl-xL NSCLC cell line compared to that of high cytoplasmic Bcl-xL cell lines. In addition, clinical data also show that the level of cytoplasmic Bcl-xL was negatively associated with radiosensitivity in NSCLC. Furthermore, we demonstrated that GEN treatment enhanced the radiosensitivity of NSCLC cells partially due to increases in Beclin-1-mediated autophagy by promoting the dissociation of Bcl-xL and Beclin-1. Taken together, these findings suggest that GEN can significantly enhance radiosensitivity by increasing apoptosis and autophagy due to inhibition of cytoplasmic Bcl-xL distribution and the interaction of Bcl-xL and Beclin-1 in NSCLC cells, respectively.

Mitochondriotropic nanoemulsified genistein-loaded vehicles for cancer therapy

Genistein (Gen), a major soy isoflavone, produces extensive pro-apoptotic anticancer effects, mediated predominantly via induction of mitochondrial damage. Based on several biophysical model criteria, our rational assumptions for the native mitochondrial selectivity of Gen allowed its design as a cationic lipid-based nanocarrier (NC) system. Proof-of-concept nano-formulations, lipidic micelles (Mic), and nanoemulsions (NEs) incorporated Gen, which serves as therapeutic and targeting moieties, specific for mitochondria. Our in vitro experimental data demonstrated superior physicochemical properties and significant cytotoxicity of Gen-NCs (five- to tenfolds lower EC50) compared to all drug controls, in hepatic and colon carcinomas. The established mitochondria-specific accumulation of the various Gen-NCs positively correlated with marked mitochondrial depolarization effects. Within first 24 h, Gen-NC treatments ultimately lead to distinct activation of intrinsic apoptotic pathway markers, such as cytosolic cytochrome c and specific caspase-9 vs. nonspecific caspases-3, 7, and 8. Such mechanistic evidence of the mitochondriotropic activity of our Gen-NC platforms favors their prospective as intracellularly targeted delivery nano-vehicles, to enhance anticancer efficacy of different co-formulated chemotherapeutic agents.

Identification of new IκBα complexes by an iterative experimental and mathematical modeling approach

The transcription factor nuclear factor kappa-B (NFκB) is a key regulator of pro-inflammatory and pro-proliferative processes. Accordingly, uncontrolled NFκB activity may contribute to the development of severe diseases when the regulatory system is impaired. Since NFκB can be triggered by a huge variety of inflammatory, pro-and anti-apoptotic stimuli, its activation underlies a complex and tightly regulated signaling network that also includes multi-layered negative feedback mechanisms. Detailed understanding of this complex signaling network is mandatory to identify sensitive parameters that may serve as targets for therapeutic interventions. While many details about canonical and non-canonical NFκB activation have been investigated, less is known about cellular IκBα pools that may tune the cellular NFκB levels. IκBα has so far exclusively been described to exist in two different forms within the cell: stably bound to NFκB or, very transiently, as unbound protein. We created a detailed mathematical model to quantitatively capture and analyze the time-resolved network behavior. By iterative refinement with numerous biological experiments, we yielded a highly identifiable model with superior predictive power which led to the hypothesis of an NFκB-lacking IκBα complex that contains stabilizing IKK subunits. We provide evidence that other but canonical pathways exist that may affect the cellular IκBα status. This additional IκBα:IKKγ complex revealed may serve as storage for the inhibitor to antagonize undesired NFκB activation under physiological and pathophysiological conditions.

In unstimulated cells, the transcription factor NFκB resides in the cytosol bound to its inhibitor IκBα. Canonical activation of NFκB by numerous stimuli leads to proteasomal depletion of IκBα, thereby liberating NFκB to translocate into the nucleus to induce transcription of genes leading to proliferation, angiogenesis, metastasis, or chronic inflammation. Consequently, only transient activity needs to be warranted by immediate NFκB-dependent induction of negative regulatory mechanisms, including up-regulation of its inhibitor IκBα. Resynthesized IκBα consequently terminates NFκB activity by binding to its nuclear localization sequence. However, under physiological or pathophysiological conditions, random NFκB activation may occur, which needs to be avoided in order to guarantee proper cellular function. Using detailed dynamical modeling, we have now identified an additional IκBα containing complex to exist in un-stimulated cells which lacks NFκB but includes IKKγ (IκBα:IKKγ complex). This additional IκBα is not depleted from cells in the canonical fashion and may therefore serve as a cellular backup to avoid random NFκB activation.

Antioxidant function of isoflavone and 3,3'-diindolylmethane: are they important for cancer prevention and therapy?

SIGNIFICANCE

Oxidative stress has been mechanistically linked with aging and chronic diseases, including cancer. In fact, oxidative stress status, chronic disease-related inflammation, and cancer occurred in the aging population are tightly correlated. It is well known that the activation of nuclear factor kappa B (NF-κB) plays important roles in oxidative stress, inflammation, and carcinogenesis. Therefore, targeting NF-κB is an important preventive or therapeutic strategy against oxidative stress, inflammation, and cancer.

RECENT ADVANCES

A variety of natural compounds has been found to reduce oxidative stress through their antioxidant activity. Among them, isoflavone, indole-3-carbinol (I3C), and its in vivo dimeric compound 3,3'-diindolylmethane (DIM) have shown their promising effects on the inhibition of NF-κB with corresponding reduction of oxidative stress.

CRITICAL ISSUES

It has been found that isoflavone, I3C, and DIM could inhibit cancer development and progression by regulating multiple cellular signaling pathways that are related to oxidative stress and significantly deregulated in cancer.

FUTURE DIRECTIONS

The antioxidative and anticancer effects of these natural agents make them strong candidates for chemoprevention and/or therapy against human malignancies. However, more clinical trials are needed to evaluate the effects of isoflavone and DIM for the prevention of cancer development and also for the treatment of cancer either alone or in combination with conventional cancer therapeutics.

Molecular basis of 'hypoxic' breast cancer cell radio-sensitization: phytochemicals converge on radiation induced Rel signaling

BACKGROUND

Heterogeneously distributed hypoxic areas are a characteristic property of locally advanced breast cancers (BCa) and generally associated with therapeutic resistance, metastases, and poor patient survival. About 50% of locally advanced BCa, where radiotherapy is less effective are suggested to be due to hypoxic regions. In this study, we investigated the potential of bioactive phytochemicals in radio-sensitizing hypoxic BCa cells.

METHODS

Hypoxic (O2-2.5%; N2-92.5%; CO2-5%) MCF-7 cells were exposed to 4 Gy radiation (IR) alone or after pretreatment with Curcumin (CUR), curcumin analog EF24, neem leaf extract (NLE), Genistein (GEN), Resveratrol (RES) or raspberry extract (RSE). The cells were examined for inhibition of NFκB activity, transcriptional modulation of 88 NFκB signaling pathway genes, activation and cellular localization of radio-responsive NFκB related mediators, eNos, Erk1/2, SOD2, Akt1/2/3, p50, p65, pIκBα, TNFα, Birc-1, -2, -5 and associated induction of cell death.

RESULTS

EMSA revealed that cells exposed to phytochemicals showed complete suppression of IR-induced NFκB. Relatively, cells exposed EF24 revealed a robust inhibition of IR-induced NFκB. QPCR profiling showed induced expression of 53 NFκB signaling pathway genes after IR. Conversely, 53, 50, 53, 53, 53 and 53 of IR-induced genes were inhibited with EF24, NLE, CUR, GEN, RES and RSE respectively. In addition, 25, 29, 24, 16, 11 and 21 of 35 IR-suppressed genes were further inhibited with EF24, NLE, CUR, GEN, RES and RSE respectively. Immunoblotting revealed a significant attenuating effect of IR-modulated radio-responsive eNos, Erk1/2, SOD2, Akt1/2/3, p50, p65, pIκBα, TNFα, Birc-1, -2 and -5 with EF24, NLE, CUR, GEN, RES or RSE. Annexin V-FITC staining showed a consistent and significant induction of IR-induced cell death with these phytochemicals. Notably, EF24 robustly conferred IR-induced cell death.

CONCLUSIONS

Together, these data identifies the potential hypoxic cell radio-sensitizers and further implies that the induced radio-sensitization may be exerted by selectively targeting IR-induced NFκB signaling.

Mitigation of radiation-induced lung injury with EUK-207 and genistein: effects in adolescent rats

Exposure of civilian populations to radiation due to accident, war or terrorist act is an increasing concern. The lung is one of the more radiosensitive organs that may be affected in people receiving partial-body irradiation and radiation injury in lung is thought to be associated with the development of a prolonged inflammatory response. Here we examined how effectively damage to the lung can be mitigated by administration of drugs initiated at different times after radiation exposure and examined response in adolescent animals for comparison with the young adult animals that we had studied previously. We studied the mitigation efficacy of the isoflavone genistein (50 mg/kg) and the salen-Mn superoxide dismutase-catalase mimetic EUK-207 (8 mg/kg), both of which have been reported to scavenge reactive oxygen species and reduce activity of the NFkB pathway. The drugs were given by subcutaneous injection to 6- to 7-week-old Fisher rats daily starting either immediately or 2 weeks after irradiation with 12 Gy to the whole thorax. The treatment was stopped at 28 weeks post irradiation and the animals were assessed for levels of inflammatory cytokines, activated macrophages, oxidative damage and fibrosis at 48 weeks post irradiation. We demonstrated that both genistein and EUK-207 delayed and suppressed the increased breathing rate associated with pneumonitis. These agents also reduced levels of oxidative damage (50-100%), levels of TGF-β1 expression (75-100%), activated macrophages (20-60%) and fibrosis (60-80%). The adolescent rats developed pneumonitis earlier following irradiation of the lung than did the adult rats leading to greater severe morbidity requiring euthanasia (∼37% in adolescents vs. ∼10% in young adults) but the extent of the mitigation of the damage was similar or slightly greater.

Involvement of nuclear factor κB (NF-κB) in the downregulation of cyclooxygenase-2 (COX-2) by genistein in gastric cancer cells

Genistein induces growth inhibition in various human cancer cell lines but its mechanism of action remains unknown. This study determined whether the effect of genistein is mediated via suppression of cyclo-oxygenase (COX)-2 protein, and elucidated the mechanism of action of this effect in the human gastric cancer cell line BGC-823. Genistein treatment inhibited cell proliferation and induced apoptosis in a dose- and time-dependent manner; Western blotting analysis indicated a significant dose-dependent decrease in COX-2 protein levels. Genistein treatment exerted a significant inhibitory effect on activation of the transcription factor nuclear factor κB (NF-κB). Additionally, the NF-κB inhibitor pyrrolidine dithiocarbamate caused a reduction in COX-2 protein levels and NF-κB activation, similar to the effect of genistein. Suppression of COX-2 protein may be important for the antiproliferative and proapoptotic effects of genistein in BGC-823 cells, and these effects may be partly mediated through the NF-κB pathway.

Mitigation of lung injury after accidental exposure to radiation

There is a serious need to develop effective mitigators against accidental radiation exposures. In radiation accidents, many people may receive nonuniform whole-body or partial-body irradiation. The lung is one of the more radiosensitive organs, demonstrating pneumonitis and fibrosis that are believed to develop at least partially because of radiation-induced chronic inflammation. Here we addressed the crucial questions of how damage to the lung can be mitigated and whether the response is affected by irradiation to the rest of the body. We examined the widely used dietary supplement genistein given at two dietary levels (750 or 3750 mg/kg) to Fischer rats irradiated with 12 Gy to the lung or 8 Gy to the lung + 4 Gy to the whole body excluding the head and tail (whole torso). We found that genistein had promising mitigating effects on oxidative damage, pneumonitis and fibrosis even at late times (36 weeks) when drug treatment was initiated 1 week after irradiation and stopped at 28 weeks postirradiation. The higher dose of genistein showed no greater beneficial effect. Combined lung and whole-torso irradiation caused more lung-related severe morbidity resulting in euthanasia of the animals than lung irradiation alone.

Induction of cancer cell death by isoflavone: the role of multiple signaling pathways

Soy isoflavones have been documented as dietary nutrients broadly classified as "natural agents" which plays important roles in reducing the incidence of hormone-related cancers in Asian countries, and have shown inhibitory effects on cancer development and progression in vitro and in vivo, suggesting the cancer preventive or therapeutic activity of soy isoflavones against cancers. Emerging experimental evidence shows that isoflavones could induce cancer cell death by regulating multiple cellular signaling pathways including Akt, NF-κB, MAPK, Wnt, androgen receptor (AR), p53 and Notch signaling, all of which have been found to be deregulated in cancer cells. Therefore, homeostatic regulation of these important cellular signaling pathways by isoflavones could be useful for the activation of cell death signaling, which could result in the induction of apoptosis of both pre-cancerous and/or cancerous cells without affecting normal cells. In this article, we have attempted to summarize the current state-of-our-knowledge regarding the induction of cancer cell death pathways by isoflavones, which is believed to be mediated through the regulation of multiple cellular signaling pathways. The knowledge gained from this article will provide a comprehensive view on the molecular mechanism(s) by which soy isoflavones may exert their effects on the prevention of tumor progression and/or treatment of human malignancies, which would also aid in stimulating further in-depth mechanistic research and foster the initiation of novel clinical trials.

Mitigation of radiation-induced lung injury by genistein and EUK-207

PURPOSE

We examined the effects of genistein and/or Eukarion (EUK)-207 on radiation-induced lung damage and investigated whether treatment for 0-14 weeks (wks) post-irradiation (PI) would mitigate late lung injury.

MATERIALS AND METHODS

The lungs of female Sprague-Dawley (SD) rats were irradiated with 10 Gy. EUK-207 was delivered by infusion and genistein was delivered as a dietary supplement starting immediately after irradiation (post irradiation [PI]) and continuing until 14 wks PI. Rats were sacrificed at 0, 4, 8, 14 and 28 wks PI. Breathing rate was monitored and lung fibrosis assessed by lung hydroxyproline content at 28 wks. DNA damage was assessed by micronucleus (MN) assay and 8-hydroxy-2-deoxyguanosine (8-OHdG) levels. The expression of the cytokines Interleukin (IL)-1α, IL-1β, IL-6, Tumor necrosis factor (TNF)-α and Transforming growth factor (TGF)-β1, and macrophage activation were analyzed by immunohistochemistry.

RESULTS

Increases in breathing rate observed in the irradiated rats were significantly reduced by both drug treatments during the pneumonitis phase and the later fibrosis phase. The drug treatments decreased micronuclei (MN) formation from 4-14 wks but by 28 wks the MN levels had increased again. The 8-OHdG levels were lower in the drug treated animals at all time points. Hydroxyproline content and levels of activated macrophages were decreased at 28 wks in all drug treated rats. The treatments had limited effects on the expression of the cytokines.

CONCLUSION

Genistein and EUK-207 can provide partial mitigation of radiation-induced lung damage out to at least 28 wks PI even after cessation of treatment at 14 wks PI.

Soy isoflavones and virus infections

Isoflavones and their related flavonoid compounds exert antiviral properties in vitro and in vivo against a wide range of viruses. Genistein is, by far, the most studied soy isoflavone in this regard, and it has been shown to inhibit the infectivity of enveloped or nonenveloped viruses, as well as single-stranded or double-stranded RNA or DNA viruses. At concentrations ranging from physiological to supraphysiological (3.7-370 muM), flavonoids, including genistein, have been shown to reduce the infectivity of a variety of viruses affecting humans and animals, including adenovirus, herpes simplex virus, human immunodeficiency virus, porcine reproductive and respiratory syndrome virus, and rotavirus. Although the biological properties of the flavonoids are well studied, the mechanisms of action underlying their antiviral properties have not been fully elucidated. Current results suggest a combination of effects on both the virus and the host cell. Isoflavones have been reported to affect virus binding, entry, replication, viral protein translation and formation of certain virus envelope glycoprotein complexes. Isoflavones also affect a variety of host cell signaling processes, including induction of gene transcription factors and secretion of cytokines. The efficacy of isoflavones and related flavonoids in virus infectivity in in vitro bioassays is dependent on the dose, frequency of administration and combination of isoflavones used. Despite promising in vitro results, there is lack of data confirming the in vivo efficacy of soy isoflavones. Thus, investigations using appropriate in vivo virus infectivity models to examine pharmacological and especially physiological doses of flavonoids are warranted.

Genistein inhibits the development of atherosclerosis via inhibiting NF-κB and VCAM-1 expression in LDLR knockout mice

Diet can be an important factor that influences risks for cardiovascular disease. Genistein (4′,5,7-trihydroxyisoflavone), rich in soy, is one candidate that may benefit the cardiovascular system. Here, we explored the effect of genistein in atherosclerosis (AS) development in an in vivo mouse model. Low-density lipoprotein receptor (LDLR) knockout mice were allocated to control, model, and genistein groups. Our results showed that genistein significantly reduced the formation and development of atherosclerotic plaques ((4.68 ± 1.18) ×106 versus (6.65 ± 1.51) ×106 µm2, p < 0.05). In the genistein group, compared with the model group, total antioxidant capacity (TAC) level was 85.5 ± 15.6 versus 203.4 ± 32.6 mmol/L (p < 0.01); malondialdehyde (MDA) level was 3.79 ± 0.28 versus 3.06 ± 0.31 mmol/L (p < 0.01), and superoxide dismutase (SOD) activity was 86.1 ± 6.1 versus 139.1 ± 25.1 U/mL (p < 0.01). Therefore, genistein was able to enhance serum antioxidative ability in our mouse model. Genistein had no influence, however, on serum cholesterol and lipid profiles. Genistein also markedly downregulated the expression of nuclear factor (NF)-κB and vascular cell adhesion molecule (VCAM)-1 in aortas of mice (p < 0.05). These observations suggest that genistein may inhibit AS in LDLR−/− mice via enhancing serum antioxidation and downregulating NF-κB and VCAM-1 expression in the aorta.

Genistein induces cell apoptosis in MDA-MB-231 breast cancer cells via the mitogen-activated protein kinase pathway

Genistein, an isoflavonoid present in soybeans, exhibits anti-carcinogenic effects. Several studies have shown that genistein inhibits cell proliferation and triggers apoptosis in human breast cancer cells. In this study, we assessed the role of the MEK-ERK cascade in the regulation of genistein-mediated cell apoptosis in MDA-MB-231 cells. The results indicate that genistein, in a concentration-dependent manner, suppresses the protein levels of MEK5, total ERK5, and phospho-ERK5, effects that are consistent with inhibition of cell growth and induction of apoptosis. Exposure of these cells to genistein results in a concentration-dependent decrease in NF-kappaB/p65 protein levels and DNA-binding activity of NF-kappaB. Genistein down-regulates Bcl-2 and up-regulates Bax. NF-kappaB binding sites are present in the promoter of Bcl-2, suggesting that genistein might inhibit the expression of Bcl-2 through down-regulation of NF-kappaB. Exposure of MDA-MB-231 cells to genistein results in cleavage of caspase-3 and induction of caspase-3 activity in a concentration-dependent manner. Genistein inhibits NF-kappaB activity via the MEK5/ERK5 pathway; it also inhibits cell growth and induces apoptosis. In conclusion, inhibition of the MEK5/ERK5/NF-kappaB pathway may be an important mechanism by which genistein suppresses cell growth and induces apoptosis.

Soy isoflavones in the management of postmenopausal osteoporosis

This is a review article designed to address the effects of soy isoflavones on bone metabolism in postmenopausal women and their place in the prevention and treatment of postmenopausal osteoporosis. Soy isoflavones are natural products that could be used as an alternative to menopausal hormone therapy because they are structurally and functionally related to 17beta-estradiol. In vitro and animal studies have shown that they act in multiple ways to exert their bone-supporting effects. They act on both osteoblasts and osteoclasts through genomic and nongenomic pathways. Epidemiological studies and clinical trials suggest that soy isoflavones have beneficial effects on bone mineral density, bone turnover markers, and bone mechanical strength in postmenopausal women. However, there are conflicting results related to differences in study design, estrogen status of the body, metabolism of isoflavones among individuals, and other dietary factors. The long-term safety of soy isoflavone supplements remains to be demonstrated.

Effects of dietary flavonoids on apoptotic pathways related to cancer chemoprevention

Epidemiological studies have described the beneficial effects of dietary polyphenols (flavonoids) on the reduction of the risk of chronic diseases, including cancer. Moreover, it has been shown that flavonoids, such as quercetin in apples, epigallocatechin-3-gallate in green tea and genistein in soya, induce apoptosis. This programmed cell death plays a critical role in physiological functions, but there is underlying dysregulation of apoptosis in numerous pathological situations such as Parkinson's disease, Alzheimer's disease and cancer. At the molecular level, flavonoids have been reported to modulate a number of key elements in cellular signal transduction pathways linked to the apoptotic process (caspases and bcl-2 genes), but that regulation and induction of apoptosis are unclear. The aim of this review is to provide insights into the molecular basis of the potential chemopreventive activities of representative flavonoids, with emphasis on their ability to control intracellular signaling cascades responsible for regulating apoptosis, a relevant target in cancer-preventive approach.

High expression levels of nuclear factor kappa B and gelatinases in the tumorigenesis of oral squamous cell carcinoma

BACKGROUND

The cellular mechanisms involved in transformation of a premalignant/potentially malignant oral lesion to a malignant one remain unclear. Previous studies have documented a direct involvement of matrix metalloproteinase (MMP) overexpression in the development and progression of head and neck squamous cell carcinoma (HNSCC). MMP activation, particularly MMP2 and MMP9, observed in different cancers, has been shown to be mediated via the transcription factor nuclear factor kappa B (NF-kappaB). The present study analyzes the clinical significance of gelatinases and NF-kappaB in various histologic phases of human oral tumor progression.

METHODS

Methodology included immunohistochemistry for MMP2, MMP9, p50, and p65 components of NF-kappaB and IkappaBalpha (inhibitor kappaBalpha). Gelatin zymography was carried out to determine the extent of gelatinolytic activity. Western blotting was used to confirm the gelatinolytic bands of zymogram, and electrophoretic mobility shift assay (EMSA) was carried out to confirm NF-kappaB activation.

RESULTS

A gradual increase was evident in the intensity of the expression and gelatinolytic activity of gelatinase paralleling the histologic progression of malignancy. This finding supports the histologic evidence of tumor invasion occurring in the transition between premalignancy and invasive cancer. Nuclear translocation of NF-kappaB (p50-p65 form) gradually progresses through the premalignant phase of oral tissue to the invasive phase, showing NF-kappaB activation during oral tumorigenesis. NF-kappaB activation correlatively paralleled the pattern of expression of gelatinases.

CONCLUSIONS

The results of this study suggest a regulatory role for NF-kappaB on activation of gelatinases during malignant transformation in the oral mucosa.

Chemosensitization and radiosensitization of tumors by plant polyphenols

The treatment of cancer with chemotherapeutic agents and radiation has two major problems: time-dependent development of tumor resistance to therapy (chemoresistance and radioresistance) and nonspecific toxicity toward normal cells. Many plant-derived polyphenols have been studied intently for their potential chemopreventive properties and are pharmacologically safe. These compounds include genistein, curcumin, resveratrol, silymarin, caffeic acid phenethyl ester, flavopiridol, emodin, green tea polyphenols, piperine, oleandrin, ursolic acid, and betulinic acid. Recent research has suggested that these plant polyphenols might be used to sensitize tumor cells to chemotherapeutic agents and radiation therapy by inhibiting pathways that lead to treatment resistance. These agents have also been found to be protective from therapy-associated toxicities. How these polyphenols protect normal cells and sensitize tumor cells to treatment is discussed in this review.

Actinodaphnine induces apoptosis through increased nitric oxide, reactive oxygen species and down-regulation of NF-kappaB signaling in human hepatoma Mahlavu cells

Actinodaphnine, extracted from Cinnamomum insularimontanum (Lauraceae), possesses cytotoxicity in some cancers, but the mechanism by which actinodaphnine induces apoptosis in human hepatoma cells remains poorly understood. In this study, we investigated the mechanisms of apoptosis induced by actinodaphnine in human hepatoma Mahlavu cells. Treatment with actinodaphnine dose-dependently induced apoptosis in Mahlavu cells that correlated with increased intracellular nitric oxide (NO) and reactive oxygen species (ROS), disruptive mitochondrial transmembrane potential (DeltaPsi(m)), and activation of caspase 3/7. Our data also demonstrated that actinodaphnine down-regulated activity of nuclear factor kappaB (NF-kappaB). The apoptotic response to actinodaphnine was markedly decreased in Mahlavu cells pretreated with dexsamethasone, a NO inhibitor, N-acetylcysteine (NAC), an antioxidant, and Boc-Asp(OMe)-fmk, a broad caspases inhibitor. These results suggested that actinodaphnine-induced apoptosis is initially mediated through the NO and/or ROS increase and caspases-dependent pathway. In conclusion, our results indicate that an increase of ROS and/or NO is the initial essential event that results in the decrease of DeltaPsi(m) and the activation of caspases that commits the cells to the apoptotic pathway in actinodaphnine-treated hepatoma Mahlavu cells.

Genistein induces apoptosis in T lymphoma cells via mitochondrial damage

The soy isoflavone genistein has been identified as having antiproliferative and apoptotic effects on various malignant cell types derived from solid tumors. Because little information regarding the effect of genistein on hematopoietic malignancies is available, we undertook this study of T-cell lymphomas. We tested the effect of genistein on murine T-cell lines derived from thymic lymphomas induced by an oncogenic murine leukemia virus. When T lymphoma cells were treated with genistein concentrations of 15 microM and greater, it was observed that the percentage of viable cells was significantly reduced in a dose- and time-dependent manner. The observed cell killing was found to be the result of apoptosis as detected by flow cytometric analysis of cells stained with annexin V and propidium iodide and assays for caspase-3 activation and DNA fragmentation. Cell staining with the mitochondrial specific dye JC-1 and detection of caspase-9 activation revealed that genistein produced mitochondrial depolarization as an early step in the induction of apoptosis. Bongkrekic acid inhibition of mitochondrial depolarization identified the mitochondria permeability transition pore (PTP) as a potential target of genistein activity. These results indicate that the induction of apoptosis by pharmacological concentrations of genistein in T lymphoma cells occurs via mitochondrial damage with the involvement of the PTP.

Soy isoflavone phyto-pharmaceuticals in interleukin-6 affections. Multi-purpose nutraceuticals at the crossroad of hormone replacement, anti-cancer and anti-inflammatory therapy

Interleukin-6 is a pleiotropic cytokine which plays a crucial role in immune physiology and is tightly controlled by hormonal feedback mechanisms. After menopause or andropause, loss of the normally inhibiting sex steroids (estrogen, testosterone) results in elevated IL6 levels that are further progressively increasing with age. Interestingly, excessive IL6 production promotes tumorigenesis (breast, prostate, lung, colon, ovarian), and accounts for several disease-associated pathologies and phenotypical changes of advanced age, such as osteoporosis, rheumatoid arthritis, multiple myeloma, neurodegenerative diseases and frailty. In this respect, pharmacological modulation of IL6 gene expression levels may have therapeutical benefit in preventing cancer progression, ageing discomforts and restoring immune homeostasis. Although "plant extracts" are used in folk medicine within living memory, it is only since the 20th century that numerous scientific investigations have been performed to discover potential health-protective food compounds or "nutraceuticals" which might prevent cancer and ageing diseases. About 2000 years ago, Hippocrates already highlighted "Let food be your medicine and medicine be your food". Various nutrients in the diet play a crucial role in maintaining an "optimal" immune response, such that deficient or excessive intakes can have negative consequences on the organism's immune status and susceptibility to a variety of pathologies. Over the last few decades, various immune-modulating nutrients have been identified, which interfere with IL6 gene expression. Currently, a broad range of phyto-pharmaceuticals with a claimed hormonal activity, called "phyto-estrogens", is recommended for prevention of various diseases related to a disturbed hormonal balance (i.e. menopausal ailments and/or prostate/breast cancer). In this respect, there is a renewed interest in soy isoflavones (genistein, daidzein, biochanin) as potential superior alternatives to the synthetic selective estrogen receptor modulators (SERMs), which are currently applied in hormone replacement therapy (HRT). As phyto-chemicals integrate hormonal ligand activities and interference with signaling cascades, therapeutic use may not be restricted to hormonal ailments only, but may have applications in cancer chemoprevention and/or NF-kappaB-related inflammatory disorders as well.