Inositol hexaphosphate inhibits growth and induces G1 arrest and apoptotic death of androgen-dependent human prostate carcinoma LNCaP cells

The Role of Inositols in Endocrine and Neuroendocrine Tumors

Inositols have demonstrated a role in cancer prevention and treatment in many kinds of neoplasms. Their molecular mechanisms vary from the regulation of survival and proliferative pathways to the modulation of immunity and oxidative stress. The dysregulation of many pathways and mechanisms regulated by inositols has been demonstrated in endocrine and neuroendocrine tumors but the role of inositol supplementation in this context has not been clarified. The aim of this review is to summarize the molecular basis of the possible role of inositols in endocrine and neuroendocrine tumors, proposing it as an adjuvant therapy.

Phytate Intake, Health and Disease: "Let Thy Food Be Thy Medicine and Medicine Be Thy Food"

Phytate (myo-inositol hexakisphosphate or InsP6) is the main phosphorus reservoir that is present in almost all wholegrains, legumes, and oilseeds. It is a major component of the Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets. Phytate is recognized as a nutraceutical and is classified by the Food and Drug Administration (FDA) as Generally Recognized As Safe (GRAS). Phytate has been shown to be effective in treating or preventing certain diseases. Phytate has been shown to inhibit calcium salt crystallization and, therefore, to reduce vascular calcifications, calcium renal calculi and soft tissue calcifications. Moreover, the adsorption of phytate to the crystal faces can inhibit hydroxyapatite dissolution and bone resorption, thereby playing a role in the treatment/prevention of bone mass loss. Phytate has a potent antioxidation and anti-inflammatory action. It is capable of inhibiting lipid peroxidation through iron chelation, reducing iron-related free radical generation. As this has the effect of mitigating neuronal damage and loss, phytate shows promise in the treatment/prevention of neurodegenerative disease. It is reported that phytate improves lipid and carbohydrate metabolism, increases adiponectin, decreases leptin and reduces protein glycation, which is linked with macrovascular and microvascular diabetes complications. In this review, we summarize the benefits of phytate intake as seen in in vitro, animal model, epidemiological and clinical trials, and we also identify questions to answer in the future.

Identification of novel serological autoantibodies in Chinese prostate cancer patients using high-throughput protein arrays

Autoantibody (AAb) has a prominent role in prostate cancer (PCa), with few studies profiling the AAb landscape in Chinese patients. Therefore, the AAb landscape in Chinese patients was characterized using protein arrays. First, in the discovery phase, Huprot arrays outlined autoimmune profiles against ~ 21,888 proteins from 57 samples. In the verification phase, the PCa-focused arrays detected 25 AAbs selected from the discovery phase within 178 samples. Then, PCa was detected using a backpropagation artificial neural network (BPANN) model. In the validation phase, an enzyme-linked immunosorbent assay (ELISA) was used to validate four AAb biomarkers from 196 samples. Huprot arrays profiled distinct PCa, benign prostate diseases (BPD), and health AAb landscapes. PCa-focused array depicted that IFIT5 and CPOX AAbs could distinguish PCa from health with an area under curve (AUC) of 0.71 and 0.70, respectively. PAH and FCER2 AAbs had AUCs of 0.86 and 0.88 in discriminating PCa from BPD. Particularly, PAH AAb detected patients in the prostate-specific antigen (PSA) gray zone with an AUC of 0.86. Meanwhile, the BPANN model of 4-AAb (IFIT5, PAH, FCER2, CPOX) panel attained AUC of 0.83 among the two cohorts for detecting patients with gray-zone PSA. In the validation cohort, the IFIT5 AAb was upregulated in PCa compared to health (p < 0.001). Compared with BPD, PAH and FCER2 AAbs were significantly elevated in PCa (p = 0.012 and 0.039). We have demonstrated the first extensive profiling of autoantibodies in Chinese PCa patients, identifying novel diagnostic AAb biomarkers, especially for identification of gray-zone-PSA patients.

Biodegradable Amorphous Copper Iron Tellurite Promoting the Utilization of Fenton-Like Ions for Efficient Synergistic Cancer Theranostics

The major hurdles of chemodynamic therapy (CDT) are nondegradability and low-efficiency utilization of chemodynamic agents, and intracellular glutathione (GSH)-induced rapid scavenging of hydroxyl radicals (•OH). Here, a biodegradable a-CFT@IP6@BSA agent is reported for efficient cancer therapy by encapsulating amorphous copper iron tellurite nanoparticles (a-CFT NPs) into inositol hexaphosphate (IP6) and bovine serum albumin (BSA). The biggest merits of this agent are the GSH responsive degradation and amorphous structure, allowing the tumor-specific release of plenty of Cu⁺ ions and their high-efficiency utilization for •OH production via the Fenton-like reaction. Besides, the released Cu⁺ ions can deplete the intracellular GSH and thereby protect •OH from scavenging, greatly improving the CDT efficiency. Further, it is found that the a-CFT@IP6@BSA NP treatment down-regulates the levels of glutathione peroxidase 4 and BCL-2, indicating GSH depletion-associated ferroptosis and IP6-induced apoptotic death of cancer cells. Utilizing the T₁/T₂ dual-modal magnetic resonance imaging capability, the a-CFT@IP6@BSA NPs are demonstrated with excellent in vivo anticancer efficiency and have great potential for imaging-guided cancer treatment.

Signalling Properties of Inositol Polyphosphates

Several studies have identified specific signalling functions for inositol polyphosphates (IPs) in different cell types and have led to the accumulation of new information regarding their cellular roles as well as new insights into their cellular production. These studies have revealed that interaction of IPs with several proteins is critical for stabilization of protein complexes and for modulation of enzymatic activity. This has not only revealed their importance in regulation of several cellular processes but it has also highlighted the possibility of new pharmacological interventions in multiple diseases, including cancer. In this review, we describe some of the intracellular roles of IPs and we discuss the pharmacological opportunities that modulation of IPs levels can provide.

Regulation of MicroRNA-155 and Its Related Genes Expression by Inositol Hexaphosphate in Colon Cancer Cells

Inositol hexaphosphate (IP6), a natural dietary component, has been found as an antitumor agent by stimulating apoptosis and inhibiting cancer cell proliferation, their migration, and metastasis in diverse cancers including colon cancer. However, molecular mechanisms of its action have not been well understood. In recent years, microRNAs (miRNAs) have been reported to play important roles in a broad range of biologic processes, such as cell growth, proliferation, apoptosis, or autophagy. These small noncoding molecules regulate post-transcriptional expression of targets genes via degradation of transcript or inhibition of protein synthesis. Aberrant expression and/or dysregulation of miRNAs have been characterized during tumor development and progression, thus, they are potential molecular targets for cancer prevention. The aim of this study was to investigate the effect of IP6 on the miRNAs expression profile in Caco-2 colon cancer cells. 84 miRNAs were analyzed in Caco-2 cells treated with 2.5 mM and 5 mM IP6 by the use of PCR (Polymerase Chain Reaction) array. The effect of 5 mM IP6 on selected potential miR-155 targets was determined by real-time (RT)-qPCR and ELISA (quantitative Polymerase Chain Reaction and Enzyme-Linked Immunosorbent Assay )method. The results indicated alteration in the specific 10 miRNA expression in human colon cancer cells following their treatment with 5 mM IP6. It down-regulated 8 miRNAs (miR-155, miR-210, miR-144, miR-194, miR-26b, miR-126, miR-302c, and miR-29a) and up-regulated 2 miRNAs (miR-223 and miR-196b). In silico analysis revealed that FOXO3a, HIF-1α, and ELK3 mRNAs are those of predicted targets of miR-155. IP6 at the concentration of 5 mM markedly induced FOXO3a and HIF-1a genes’ expression at both mRNA and protein level and decreased the amount of ELK3 mRNA as well as protein concentration in comparison to the control. In conclusion, the present study indicates that one of the mechanisms of antitumor potential of IP6 is down-regulation of the miR-155 expression in human colon cancer cells. Moreover, the expression of genes that are targeted by miRNA are also modulated by IP6.

Inositol hexaphosphate plus inositol induced complete remission in stage IV melanoma: a case report

Inositol hexaphosphate (IP6) also called phytic acid is a polyphosphorylated carbohydrate naturally found in cereals, nuts, grains, and high-fiber-containing foods. It has been shown to inhibit the growth of many different tumor cell lines both in vitro and in vivo like colon, pancreas, liver, prostate, and even melanoma. Vitamin B inositol is a precursor of IP6 and another naturally occurring compound with anticancer properties. We present a case report of a patient with metastatic melanoma who declined traditional therapy and opted to try over the counter supplement IP6+inositol instead. To our surprise, the patient achieved a complete remission and remains in remission 3 years later. On the basis of this case and previous preclinical studies, we believe further research is indicated in exploring antiproliferative and potential immune stimulating effects of IP6+inositol in patients with metastatic melanoma.

New options of cancer treatment employing InsP6

Many mechanistic studies have been performed to analyze the cellular functions of the highly phosphorylated molecule inositol hexakisphosphate (InsP₆) in health and disease. While the physiological intracellular functions are well described, the mechanism of potential pharmacological effects on cancer cell proliferation is still controversial. There are numerous studies demonstrating that a high InsP₆ concentration (≥75 µM) inhibits growth of cancer cells in vitro and in vivo. Thus, there is no doubt that InsP₆ exhibits anticancer activity but the mechanism underlying the cellular effects of extracellular InsP₆ on cancer cells is far from being understood. In addition, studies on the inhibitory effect of InsP₆ on cancer progression in animal models ignore aspects of its bioavailability. Here, we review and critically discuss the uptake mechanism and the intracellular involvement in signaling pathways of InsP₆ in cancer cells. We take into account the controversial findings on InsP₆ plasma concentration, which is a critical aspect of pharmacological accessibility of InsP₆ for cancer treatment. Further, we discuss novel findings with respect to the effect of InsP₆ on normal and immune cells as well as on platelet aggregate size. Our goal is to stimulate further mechanistic studies into novel directions considering previously disregarded aspects of InsP₆. Only when we fully understand the mechanism underlying the anticancer activity of InsP₆ novel and more efficient treatment options can be developed.

Identification of tumor suppressive role of microRNA-132 and its target gene in tumorigenesis of prostate cancer

Previous literature exists on the role of microRNA (miR)-132 in initiation and progression of various malignancies. In this study, we aimed at understanding the relationship of miR-132 of prostate tumorigenesis. We collected 32 prostate cancer tissues and adjacent non-cancerous controls, and detected the expression level of miR-132. Then the miRNA database was searched online and luciferase assay perform to understand the regulatory relationship between miR-132 and E2F5. Moreover, we also conducted real-time PCR and western blot analysis to study the mRNA and protein expression level of E2F5 among different groups (cancerous tissue, n=32; non-cancerous tissue, n=32) or cells treated with scramble control, miR-132 mimics, E2F5 siRNA and miR-132 inhibitors. miR-132 was upregulated in cancerous tissues of prostate cancer patients. E2F5 was the target of miR-132, and negative regulatory relationship between miR-132 and E2F5 was also confirmed by luciferase assay. The mRNA and protein expression level of E2F5 increased in cancerous tissue group. miR-132 decreased the expression of E2F5 in prostate cancer cells, and introduction of miR-132 reduced the viability and E2F5 and promoted the viability of prostate cancer cells. miR-132 inhibited apoptosis and E2F5 accelerated apoptosis. In conclusion, miR-132 was upregulated in cancerous tissue of prostate cancer. E2F5 was a direct target of miR-132, and downregulation of E2F5 caused by upregulation of miR-132 may contribute to the tumorigenesis of prostate cancer.

Inositol Hexaphosphate Inhibits Proliferation and Induces Apoptosis of Colon Cancer Cells by Suppressing the AKT/mTOR Signaling Pathway

AKT, a serine/threonine protein kinase and mammalian target of rapamycin (mTOR) plays a critical role in the proliferation and resistance to apoptosis that are essential to the development and progression of colon cancer. Therefore, AKT/mTOR signaling pathway has been recognized as an attractive target for anticancer therapy. Inositol hexaphosphate (InsP6), a natural occurring phytochemical, has been shown to have both preventive and therapeutic effects against various cancers, however, its exact molecular mechanisms of action are not fully understood. The aim of the in vitro study was to investigate the anticancer activity of InsP6 on colon cancer with the focus on inhibiting the AKT1 kinase and p70S6K1 as mTOR effector, in relation to proliferation and apoptosis of cells. The colon cancer Caco-2 cells were cultured using standard techniques and exposed to InsP6 at different concentrations (1 mM, 2.5 mM and 5 mM). Cellular proliferative activity was monitored by 5-bromo-2′-deoxyuridine (BrdU) incorporation into cellular DNA. Flow cytometric analysis was performed for cell cycle progression and apoptosis studies. Real-time RT-qPCR was used to validate mRNA levels of CDNK1A, CDNK1B, CASP3, CASP9, AKT1 and S6K1 genes. The concentration of p21 protein as well as the activities of caspase 3, AKT1 and p70S6K1 were determined by the ELISA method. The results revealed that IP6 inhibited proliferation and stimulated apoptosis of colon cancer cells. This effect was mediated by an increase in the expression of genes encoding p21, p27, caspase 3, caspase 9 as well a decrease in transcription of AKT1 and S6K1. InsP6 suppressed phosphorylation of AKT1 and p70S6K1, downstream effector of mTOR. Based on these studies it may be concluded that InsP6 can reduce proliferation and induce apoptosis through inhibition of the AKT/mTOR pathway and mTOR effector followed by modulation of the expression and activity of several key components of these pathways in colon cancer cells.

M4IDP, a zoledronic acid derivative, induces G1 arrest, apoptosis and autophagy in HCT116 colon carcinoma cells via blocking PI3K/Akt/mTOR pathway

AIMS

The aim of this work was to examine the antitumor effects and mechanisms of M₄IDP, a zoledronic acid derivative, on human colorectal cancer (CRC) HCT116 cells.

MAIN METHODS

The effects of M₄IDP on proliferation, cell cycle and ROS production were determined by CCK-8 and flow cytometry assays. Annexin-V-FITC/PI, Hoechst 33258, MDC staining assays and Ad-mCherry-GFP-LC3B fluorescence assay were performed to investigate apoptosis and autophagy. The effects of M₄IDP on the induction of ER stress as well as the expression of cell cycle, apoptosis and autophagy-related proteins were analyzed by western blot assay.

KEY FINDINGS

M₄IDP exhibited strong and sustained inhibitory effect on the growth of HCT116 cells. G1 arrest caused by M₄IDP might be attributed to the enhancement of p27 and reduction of cyclin D1 expression. Proper-time treatment of M₄IDP activated autophagy and promoted autophagic flux, while long-time treatment might inhibit the autophagic degradation and undermine the autophagy. M₄IDP-induced apoptosis and autophagy were related to the ROS production and subsequent ER stress. M₄IDP treatment increased the expression of PTEN, inhibited the phosphorylation of PDK1, Akt, mTOR, p70S6K, and increased the phosphorylation of GSK-3β and Bad, suggesting that the inhibition of PI3K/Akt/mTOR pathway might be involved in the antitumor activities of M₄IDP.

SIGNIFICANCE

Our study indicates the antitumor properties of M₄IDP and its potential clinical use in CRC therapy by blocking PI3K/Akt/mTOR pathway. This study also provides a better understanding of the antitumor effects and the underlying mechanisms of bisphosphonates in the field of CRC therapy.

Phytic Acid: From Antinutritional to Multiple Protection Factor of Organic Systems

Several studies have shown the benefits of natural antioxidants on health and food preservation. Phytic acid (IP6) is a natural antioxidant that is found mainly in cereals and vegetables and, for a long period of time, was considered an antinutritional factor. However, in vitro and in vivo studies have demonstrated its beneficial effects in the prevention and treatment of several pathological conditions and cancer. Despite the numerous benefits of IP6, the signs and intracellular interactions mediated by this antioxidant remain poorly understood. This review describes the main chemical and biological aspects of IP6, as well as its actions in the prevention and treatment of various diseases.

Broad Spectrum Anticancer Activity of Myo-Inositol and Inositol Hexakisphosphate

Inositols (myo-inositol and inositol hexakisphosphate) exert a wide range of critical activities in both physiological and pathological settings. Deregulated inositol metabolism has been recorded in a number of diseases, including cancer, where inositol modulates different critical pathways. Inositols inhibit pRB phosphorylation, fostering the pRB/E2F complexes formation and blocking progression along the cell cycle. Inositols reduce PI3K levels, thus counteracting the activation of the PKC/RAS/ERK pathway downstream of PI3K activation. Upstream of that pathway, inositols disrupt the ligand interaction between FGF and its receptor as well as with the EGF-transduction processes involving IGF-II receptor and AP-1 complexes. Additionally, Akt activation is severely impaired upon inositol addition. Downregulation of both Akt and ERK leads consequently to NF-kB inhibition and reduced expression of inflammatory markers (COX-2 and PGE2). Remarkably, inositol-induced downregulation of presenilin-1 interferes with the epithelial-mesenchymal transition and reduces Wnt-activation, β-catenin translocation, Notch-1, N-cadherin, and SNAI1 release. Inositols interfere also with the cytoskeleton by upregulating Focal Adhesion Kinase and E-cadherin and decreasing Fascin and Cofilin, two main components of pseudopodia, leading hence to invasiveness impairment. This effect is reinforced by the inositol-induced inhibition on metalloproteinases and ROCK1/2 release. Overall, these effects enable inositols to remodel the cytoskeleton architecture.

Sustained proliferation in cancer: Mechanisms and novel therapeutic targets

Proliferation is an important part of cancer development and progression. This is manifest by altered expression and/or activity of cell cycle related proteins. Constitutive activation of many signal transduction pathways also stimulates cell growth. Early steps in tumor development are associated with a fibrogenic response and the development of a hypoxic environment which favors the survival and proliferation of cancer stem cells. Part of the survival strategy of cancer stem cells may manifested by alterations in cell metabolism. Once tumors appear, growth and metastasis may be supported by overproduction of appropriate hormones (in hormonally dependent cancers), by promoting angiogenesis, by undergoing epithelial to mesenchymal transition, by triggering autophagy, and by taking cues from surrounding stromal cells. A number of natural compounds (e.g., curcumin, resveratrol, indole-3-carbinol, brassinin, sulforaphane, epigallocatechin-3-gallate, genistein, ellagitannins, lycopene and quercetin) have been found to inhibit one or more pathways that contribute to proliferation (e.g., hypoxia inducible factor 1, nuclear factor kappa B, phosphoinositide 3 kinase/Akt, insulin-like growth factor receptor 1, Wnt, cell cycle associated proteins, as well as androgen and estrogen receptor signaling). These data, in combination with bioinformatics analyses, will be very important for identifying signaling pathways and molecular targets that may provide early diagnostic markers and/or critical targets for the development of new drugs or drug combinations that block tumor formation and progression.

Cytotoxic effect of inositol hexaphosphate and its Ni(II) complex on human acute leukemia Jurkat T cells

Inositol hexaphosphate (InsP6) is present in cereals, legumes, nuts and seed oils and is biologically active against some tumor and cancer cells. Herein, this study aimed at evaluating the cellular toxicity, antiproliferative activity and effects on cell cycle progression of free InsP6 and InsP6-Ni(II) of leukemic T (Jurkat) and normal human cells. Treatments with InsP6 at concentrations between 1.0 and 4.0mM significantly decreased the viability of Jurkat cells, but showed no cytotoxic effect on normal human lymphocytes. Treatment with InsP6-Ni(II) complex at concentrations between 0.05 and 0.30 mM showed an anti-proliferative dose and a time-dependent effect, with significantly reduced cell viability of Jurkat cells but showed no cytotoxic effect on normal human lymphocytes as compared to the control. Ni(II) free ion was toxic to normal cells while InsP6-Ni(II) had no cytotoxic effect. The InsP6-Ni(II) complex potentiated (up to 10×) the antiproliferative effect of free InsP6 on Jurkat cells. The cytometric flow assay showed that InsP6 led to an accumulation of cells in the G0/G1 phase of the cell cycle, accompanied by a decrease in the number of cells in S and G2/M phases, whereas InsP6-Ni(II) has led to an accumulation of cells in the S and G2/M phases. Our findings showed that InsP6-Ni(II) potentiates cytotoxic effects of InsP6 on Jurkat cells and may be a potential adjuvant in the treatment of cancer.

N-Ethyl-N-nitrosourea-induced transplacental lung tumor development and its control: molecular modulations for tumor susceptibility in a mouse model

The development of lung tumors after transplacental N-ethyl-N-nitrosourea (ENU) exposure has been demonstrated in Swiss and Balb/c mice F1 mice.

Phosphoprotein phosphatase 1-interacting proteins as therapeutic targets in prostate cancer

Prostate cancer is a major public health concern worldwide, being one of the most prevalent cancers in men. Great improvements have been made both in terms of early diagnosis and therapeutics. However, there is still an urgent need for reliable biomarkers that could overcome the lack of cancer-specificity of prostate-specific antigen, as well as alternative therapeutic targets for advanced metastatic cases. Reversible phosphorylation of proteins is a post-translational modification critical to the regulation of numerous cellular processes. Phosphoprotein phosphatase 1 (PPP1) is a major serine/threonine phosphatase, whose specificity is determined by its interacting proteins. These interactors can be PPP1 substrates, regulators, or even both. Deregulation of this protein-protein interaction network alters cell dynamics and underlies the development of several cancer hallmarks. Therefore, the identification of PPP1 interactome in specific cellular context is of crucial importance. The knowledge on PPP1 complexes in prostate cancer remains scarce, with only 4 holoenzymes characterized in human prostate cancer models. However, an increasing number of PPP1 interactors have been identified as expressed in human prostate tissue, including the tumor suppressors TP53 and RB1. Efforts should be made in order to identify the role of such proteins in prostate carcinogenesis, since only 26 have yet well-recognized roles. Here, we revise literature and human protein databases to provide an in-depth knowledge on the biological significance of PPP1 complexes in human prostate carcinogenesis and their potential use as therapeutic targets for the development of new therapies for prostate cancer.

Quantitative proteomic analysis of human lung tumor xenografts treated with the ectopic ATP synthase inhibitor citreoviridin

ATP synthase is present on the plasma membrane of several types of cancer cells. Citreoviridin, an ATP synthase inhibitor, selectively suppresses the proliferation and growth of lung cancer without affecting normal cells. However, the global effects of targeting ectopic ATP synthase in vivo have not been well defined. In this study, we performed quantitative proteomic analysis using isobaric tags for relative and absolute quantitation (iTRAQ) and provided a comprehensive insight into the complicated regulation by citreoviridin in a lung cancer xenograft model. With high reproducibility of the quantitation, we obtained quantitative proteomic profiling with 2,659 proteins identified. Bioinformatics analysis of the 141 differentially expressed proteins selected by their relative abundance revealed that citreoviridin induces alterations in the expression of glucose metabolism-related enzymes in lung cancer. The up-regulation of enzymes involved in gluconeogenesis and storage of glucose indicated that citreoviridin may reduce the glycolytic intermediates for macromolecule synthesis and inhibit cell proliferation. Using comprehensive proteomics, the results identify metabolic aspects that help explain the antitumorigenic effect of citreoviridin in lung cancer, which may lead to a better understanding of the links between metabolism and tumorigenesis in cancer therapy.

In vitro regulation of cell growth and angiogenesis by inositol hexaphosphate in bladder cancer

BACKGROUND

Inositol Hexaphosphate (IP6) is a naturally occurring polyphosphorylated carbohydrate that is found in food sources high in fiber content. We hypothesized that IP6 would inhibit the cell growth rate of bladder cancer in vitro.

METHODS

T24 and TCCSUP bladder cancer cell lines were treated with titrating doses of IP6 (0.3, 0.6 and 0.9 mM/well). Cell viability and vascular endothelial growth factor levels were measured.

RESULTS

Significant reductions (p < 0.001) in cellular growth were noted in both cell lines at all doses and time points tested, with the exception of 0.3 mM IP6 at 24 hours in the T24 cell line. The percent inhibition of vascular endothelial growth factor was significantly higher than that observed in the TCCSUP cell line at 48 and 72 hours with 0.3 mM IP6 (p < 0.001). The T24 cells exhibited the same level of inhibition at 24 and 48 hours with 0.6 mM dose of IP6 and at 72 hours with the 0.3 mM dose (p < 0.001).

CONCLUSIONS

In vitro treatment of bladder cancer with the common dietary polyphosphorylated carbohydrate IP6 significantly decreased cellular growth by anti-angiogenic mechanisms. We feel that this data warrants further investigation and consideration for initiation of clinical trials to evaluate the safety and clinical utility of this agent.

Inositol hexaphosphate inhibits tumor growth, vascularity, and metabolism in TRAMP mice: a multiparametric magnetic resonance study

Herein, employing anatomical and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), we evaluated noninvasively, the in vivo, chemopreventive efficacy of inositol hexaphosphate (IP6), a major constituent of high-fiber diets, against prostate tumor growth and progression in transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Male TRAMP mice, beginning at 4 weeks of age, were fed with 1%, 2%, or 4% (w/v) IP6 in drinking water or only drinking water till 28 weeks of age and monitored using MRI over the course of study. Longitudinal assessment of prostate volumes by conventional MRI and tumor vascularity by gadolinium-based DCE-MRI showed a profound reduction in tumor size, partly due to antiangiogenic effects by IP6 treatment. As potential mechanisms of IP6 efficacy, decrease in the expression of glucose transporter GLUT-4 protein together with an increase in levels of phospho-AMP-activated kinase (AMPK(Th172)) were observed in prostate tissues of mice from IP6 fed-groups, suggesting that IP6 is interfering with the metabolic events occurring in TRAMP prostate. Investigative metabolomics study using quantitative high-resolution (1)H-NMR on prostate tissue extracts showed that IP6 significantly decreased glucose metabolism and membrane phospholipid synthesis, in addition to causing an increase in myoinositol levels in the prostate. Together, these findings show that oral IP6 supplement blocks growth and angiogenesis of prostate cancer in the TRAMP model in conjunction with metabolic events involved in tumor sustenance. This results in energy deprivation within the tumor, suggesting a practical and translational potential of IP6 treatment in suppressing growth and progression of prostate cancer in humans.

Activation of p53 signaling and inhibition of androgen receptor mediate tanshinone IIA induced G1 arrest in LNCaP prostate cancer cells

Our group previously reported that tanshinone IIA induced apoptosis via a mitochondria dependent pathway in LNCaP prostate cancer cells. In the present study, the roles of androgen receptor (AR) and p53 signaling pathways were investigated in tanshinone IIA-induced G1 arrest in LNCaP cells. Tanshinone IIA significantly inhibited the growth and proliferation of LNCaP cells by colony formation and BrdU incorporation assays, respectively. Tanshinone IIA induced cell cycle arrest at G1 phase and down-regulated cyclin D1, CDK2 and CDK4. Furthermore, tanshinone IIA activated the phosphorylation of p53 at Ser 15 residue and its downstream p21 and p27. Additionally, tanshinone IIA suppressed the expression of AR and prostate specific antigen (PSA). Conversely, silencing p53 using its specific siRNA reversed cyclin D1 expression inhibited by tanshinone IIA. However, knockdown of AR had no effect on the p53/p21/p27 signaling pathway activated by tanshinone IIA in LNCaP cells. In AR siRNA-transfected cells, tanshinone IIA did not cause cell cycle arrest and reduce cyclin D1, implying that AR is essential to induce G1 arrest by tanshinone IIA in LNCaP cells. Taken together, the findings suggest that tanshinone IIA induces G1 arrest via activation of p53 signaling and inhibition of AR in LNCaP cells.

Reduction in lipopolysaccharide-induced apoptosis of fibroblasts obtained from a patient with gingival overgrowth during nifedipine-treatment

OBJECTIVE

We have previously demonstrated that the mechanism of nifedipine (NIF)-induced gingival overgrowth is related to the observation that proliferation and cell cycle progression of gingival fibroblasts derived from NIF reactive patient (NIFr) are greater than those from NIF non-reactive patient (NIFn). Gingival overgrowth has also been reported to be a result of inhibited apoptosis of gingival fibroblasts. Apoptosis in fibroblasts is induced by lipopolysaccharide (LPS). Thus, we focused upon evaluating whether there is a difference in LPS-induced apoptosis between NIFn and NIFr.

METHODS

Both NIFn and NIFr were arrested in DMEM containing 0.5% FBS, stimulated by LPS, and assayed for apoptosis, cell cycle analysis, Western blotting, and caspase activity.

RESULTS

Compared to NIFn, the number of apoptotic cells was significantly decreased and the percentage of cells in S and G(2)/M phase was significantly increased in NIFr. The levels of Bax and cytochrome c proteins in NIFr were not up-regulated by LPS compared with NIFn. Both NIFn and NIFr displayed the following changes in protein expression: increased Bad, decreased Bcl-xL, and unchanged Bcl-2 and p53. Caspase-3 and -9 activities were significantly increased by LPS in NIFn but were unchanged in NIFr. Caspase-2 activity remained constant whilst caspase-8 activity significantly increased upon LPS treatment in both NIFn and NIFr.

CONCLUSION

Bad, Bax, cytochrome c, p53, and caspases-2, -3, -8, and -9 are pro-apoptotic proteins. Bcl-2 and Bcl-xL are anti-apoptotic proteins. Thus, the mechanism of NIF-induced gingival overgrowth might be related to decreased apoptosis in NIFr through a reduction of Bax, cytochrome c, and caspase-3 and -9.

Non-isoflavone phytochemicals in soy and their health effects

Epidemiological and clinical studies have linked consumption of soy foods with low incidences of a number of chronic diseases, such as cardiovascular diseases, cancer, and osteoporosis. Over the past decades, enormous research efforts have been made to identify bioactive components in soy. Isoflavones and soy protein have been suggested as the major bioactive components in soy and have received considerable attention. However, there are hundreds of phytochemical components in soybeans and soy-based foods. In recent years, accumulating evidence has suggested that the isoflavones or soy proteins stripped of phytochemicals only reflect certain aspects of health effects associated with soy consumption. Other phytochemicals, either alone or in combination with isoflavones or soy protein, may be involved in the health effects of soy. This review attempts to summarize major non-isoflavone phytochemicals in soy, as well as their bioavailability and health effects. In addition, a brief discussion of components formed during food processing is also included.

Effect of phytic acid on suicidal erythrocyte death

Phytic acid, an anticarcinogenic food component, stimulates apoptosis of tumor cells. Similar to apoptosis, human erythrocytes may undergo suicidal death or eryptosis, characterized by cell membrane scrambling and cell shrinkage. Triggers of eryptosis include energy depletion. Phytate intake could cause anemia, an effect attributed to iron complexation. The present experiments explored whether phytic acid influences eryptosis. Supernatant hemoglobin concentration was determined to reveal hemolysis, annexin V-binding in FACS analysis was utilized to identify erythrocytes with scrambled cell membrane, forward scatter in FACS analysis was taken as a measure of cell volume, and a luciferin-luciferase assay was employed to determine erythrocyte ATP content. As a result, phytic acid (>or=1 mM) did not lead to significant hemolysis, but significantly increased the percentage of annexin V-binding erythrocytes, significantly decreased forward scatter, and significantly decreased cellular ATP content. In conclusion, phytic acid stimulates suicidal human erythrocyte death, an effect paralleling its proapoptotic effect on nucleated cells.

Inositol hexaphosphate downregulates both constitutive and ligand-induced mitogenic and cell survival signaling, and causes caspase-mediated apoptotic death of human prostate carcinoma PC-3 cells

Constitutively active mitogenic and prosurvival signaling cascades due to aberrant expression and interaction of growth factors and their receptors are well documented in human prostate cancer (PCa). Epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1) are potent mitogens that regulate proliferation and survival of PCa cells via autocrine and paracrine loops involving both mitogen-activated protein kinase (MAPK)- and Akt-mediated signaling. Accordingly, here we assessed the effect of inositol hexaphosphate (IP6) on constitutive and ligand (EGF and IGF-1)-induced biological responses and associated signaling cascades in advanced and androgen-independent human PCa PC-3 cells. Treatment of PC-3 cells with 2 mM IP6 strongly inhibited both growth and proliferation and decreased cell viability; similar effects were also observed in other human PCa DU145 and LNCaP cells. IP6 also caused a strong apoptotic death of PC-3 cells together with caspase 3 and PARP cleavage. Mechanistic studies showed that biological effects of IP6 were associated with inhibition of both constitutive and ligand-induced Akt phosphorylation together with a decrease in total Akt levels, but a differential inhibitory effect on MAPKs extra cellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal protein kinase (JNK1/2), and p38 under constitutive and ligand-activated conditions. Under similar condition, IP6 also inhibited AP-1 DNA-binding activity and decreased nuclear levels of both phospho and total c-Fos and c-Jun. Together, these findings for the first time establish IP6 efficacy in inhibiting aberrant EGF receptor (EGFR) or IGF-1 receptor (IGF-1R) pathway-mediated sustained growth promoting and survival signaling cascades in advanced and androgen-independent human PCa PC-3 cells, which might have translational implications in advanced human PCa control and management.

3,5,3',4',5'-pentamethoxystilbene (MR-5), a synthetically methoxylated analogue of resveratrol, inhibits growth and induces G1 cell cycle arrest of human breast carcinoma MCF-7 cells

3,5,3',4',5'-pentamethoxystilbene (MR-5) is a synthetically methoxylated analogue of resveratrol and has been suggested to have antitumor activity because of structural similarity to resveratrol. Herein, we investigate the antiproliferative effect of MR-5 in human breast cancer MCF-7 cells and demonstrate that MR-5 had a more potent inhibition on cell growth compared with resveratrol and other methoxylated derivatives. Exploring the growth-inhibitory mechanisms of MR-5, we found that it is accompanied by G1 cell cycle arrest, which coincides with a marked inhibition of G1 cell cycle regulatory proteins, including decreased cyclins (D1/D3/E) and cyclin-dependent kinases (CDK2/4/6) and increased CDK inhibitors (CKIs) such as p15, p16, p21, and p27. Furthermore, the increase in CKI levels by MR-5 resulted in a concomitant increase in their interactions of CDK4 and CDK2, along with a strong inhibition in CDK4 kinase activity and the accumulation of hypophosphorylated Rb. MR-5 also modulated some critical kinase activities related to cell cycle regulation, including Akt, mitogen-activated protein kinase (ERK1/2), p38 mitogen-activated protein kinase (p38 MAPK), and focal adhesion kinase (FAK) in MCF-7 cells. In total, our results demonstrate that MR-5 affects multiple cellular targets that contribute to its antiproliferative activity in MCF-7 cells and provide novel information for synthetic chemists to design new antitumor agents with introduction of methoxylated group(s) in the basic compound.

Inositol hexaphosphate suppresses growth and induces apoptosis in prostate carcinoma cells in culture and nude mouse xenograft: PI3K-Akt pathway as potential target

Constitutive activation of phosphoinositide 3-kinase (PI3K)-Akt pathway transmits growth-regulatory signals that play a central role in promoting survival, proliferation, and angiogenesis in human prostate cancer cells. Here, we assessed the efficacy of inositol hexaphosphate (IP6) against invasive human prostate cancer PC-3 and C4-2B cells and regulation of PI3K-Akt pathway. IP6 treatment of cells suppressed proliferation, induced apoptosis along with caspase-3 and poly(ADP-ribose) polymerase (PARP) cleavage, and inhibited constitutive activation of Akt and its upstream regulators PI3K, phosphoinositide-dependent kinase-1 and integrin-linked kinase-1 (ILK1). Downstream of Akt, IP6 inhibited the phosphorylation of glycogen synthase kinase-3alpha/beta at Ser(21/9) and consequently reduced cyclin D1 expression. Efficacy studies employing PC-3 tumor xenograft growth in nude mice showed that 2% (w/v) IP6 feeding in drinking water inhibits tumor growth and weight by 52% to 59% (P < 0.001). Immunohistochemical analysis of xenografts showed that IP6 significantly reduces the expression of molecules associated with cell survival/proliferation (ILK1, phosphorylated Akt, cyclin D1, and proliferating cell nuclear antigen) and angiogenesis (platelet endothelial cell adhesion molecule-1 or CD31, vascular endothelial growth factor, endothelial nitric oxide synthase, and hypoxia-inducible factor-1alpha) together with an increase in apoptotic markers (cleaved caspase-3 and PARP). These findings suggest that, by targeting the PI3K-ILK1-Akt pathway, IP6 suppresses cell survival, proliferation, and angiogenesis but induces death in prostate cancer cells, which might have translational potential in preventing and controlling the growth of advanced and aggressive prostate cancer for which conventional chemotherapy is not effective.

Role of inositol polyphosphates in programmed cell death

The role of inositol polyphosphates (InsPs) in the mediation of cellular apoptosis was investigated in mouse MC3T3 osteoblastic cell line. Extracellular administration of InsP(4), InsP(5), and InsP(6) increased apoptosis in a dose-dependent manner. InsP(6) was more potent than InsP(5) and InsP(4) in promoting apoptosis. Inositol hexasulfate (InsS(6)), a structural analog of InsP(6), was used to determine specificity of InsP(6)-induced apoptosis as measured by acridine orange/ethidium bromide, flow cytometry, and DNA degradation. In order to study the effects of endogenous InsPs on apoptosis, we used NaF and antimycin A as treatment agents to manipulate intracellular levels of InsPs. NaF is known to increase levels of higher InsPs by inhibiting InsPs phosphatases, a process that is reversed by antimycin A because InsPs kinases are inhibited as a result of depletion of cellular ATP pools. Apoptosis was induced in MC3T3 cells in a NaF dose- and time-dependent manner. Approximately 50% apoptosis was observed at 1 mM NaF in 8 h. Prior treatment with 10 microM antimycin A for 30 min significantly reduced the NaF-induced apoptosis as compared with its control. Additionally, we measured changes in AKT phosphorylation, cleavage of caspase-3 and caspase-9, and release of cytochrome C from mitochondria into cytosol. These changes coincided with total cellular InsPs under similar conditions. The data indicated that NaF-induced changes in apoptotic markers could be due to an increased endogenous InsPs that were partially reversed by antimycin A treatment.

p21/Cip1 and p27/Kip1 Are essential molecular targets of inositol hexaphosphate for its antitumor efficacy against prostate cancer

Inositol hexaphosphate (IP6) causes G(1) arrest and increases cyclin-dependent kinase inhibitors p21/Cip1 and p27/Kip1 protein levels in human prostate cancer (PCa) DU145 cells lacking functional p53. However, whether cyclin-dependent kinase inhibitor I induction by IP6 plays any role in its antitumor efficacy is unknown. Herein, we observed that either p21 or p27 knockdown by small interfering RNA has no considerable effect on IP6-induced G(1) arrest, growth inhibition, and death in DU145 cells; however, the simultaneous knockdown of both p21 and p27 reversed the effects of IP6. To further confirm these findings both in vitro and in vivo, we generated DU145 cell variants with knockdown levels of p21 (DU-p21), p27 (DU-p27), or both (DU-p21+p27) via retroviral transduction of respective short hairpin RNAs. Knocking down p21 or p27 individually did not alter IP6-caused cell growth inhibition and G(1) arrest; however, their simultaneous ablation completely reversed the effects of IP6. In tumor xenograft studies, IP6 (2% w/v, in drinking water) caused a comparable reduction in tumor volume (40-46%) and tumor cell proliferation (26-28%) in DU-EV (control), DU-p21, and DU-p27 tumors but lost most of its effect in DU-p21+p27 tumors. IP6-caused apoptosis also occurred in a Cip/Kip-dependent manner because DU-p21+p27 cells were completely resistant to IP6-induced apoptosis both in cell culture and xenograft. Together, these results provide evidence, for the first time, of the critical role of p21 and p27 in mediating the anticancer efficacy of IP6, and suggest their redundant role in the antiproliferative and proapoptotic effects of IP6 in p53-lacking human PCa cells, both in vitro and in vivo.

Oligomeric proanthocyanidin complexes (OPC) exert anti-proliferative and pro-apoptotic effects on prostate cancer cells

BACKGROUND

Oligomeric proanthocyanidin complexes (OPC) are extracted from grape seeds or maritime pine bark and have been used for enhancement of capillary stability and lymphatic drainage. Since a role for OPC in cancer prevention was postulated, we asked whether they have an effect on prostate cancer cells.

METHODS

Cell proliferation was determined by (3)H-thymidine assay and cell cycle status was analyzed on a flow cytometer. Expression of regulators of proliferation and apoptosis was determined by Western blot.

RESULTS

We found that androgen-responsive cells LNCaP are more sensitive to OPC in terms of inhibition of proliferation in comparison to androgen receptor-negative PC3 or DU145 cells. Treatment with OPC resulted in a decrease in the percentage of LNCaP cells in the S phase and an increase in the percentage of cells in sub G1 phase. The anti-proliferative and pro-apoptotic effect of OPC in the LNCaP cell line was associated with down-regulation of expression of the androgen receptor. Interestingly, similar regulatory effects of OPC, such as inhibition of expression of cyclin-dependent kinases and cyclins and stimulation of tumor suppressors p21 and p27, were seen in LNCaP and PC3 cells. Favorable changes in the Bcl-2/Bax ratio were observed in LNCaP and PC3 cells after the treatment with OPC. OPC caused an increase of phosphorylated mitogen-activated protein kinase p44 and p42, thus suggesting induction of cellular differentiation.

CONCLUSIONS

We conclude that OPC is a candidate that fulfills criteria for chemopreventive strategies in prostate cancer that might be established in following in vivo studies.

Enhanced killing of androgen-independent prostate cancer cells using inositol hexakisphosphate in combination with proteasome inhibitors

Effective treatments for androgen-independent prostate cancer (AIPCa) are lacking. To address this, emerging therapeutics such as proteasome inhibitors are currently undergoing clinical trials. Inositol hexakisphosphate (IP6) is an orally non-toxic phytochemical that exhibits antitumour activity against several types of cancer including PCa. We have previously shown that treatment of PC3 cells with IP6 induces the transcription of a subset of nuclear factor-κB (NF-κB)-responsive and pro-apoptotic BCL-2 family genes. In this study, we report that although NF-κB subunits p50/p65 translocate to the nucleus of PC3 cells in response to IP6, inhibition of NF-κB-mediated transcription using non-degradable inhibitor of κB (IκB)-α does not modulate IP6 sensitivity. Treatment with IP6 also leads to increased protein levels of PUMA, BIK/NBK and NOXA between 4 and 8 h of treatment and decreased levels of MCL-1 and BCL-2 after 24 h. Although blocking transcription using actinomycin D does not modulate PC3 cell sensitivity to IP6, inhibition of protein translation using cycloheximide has a significant protective effect. In contrast, blocking proteasome-mediated protein degradation using MG-132 significantly enhances the ability of IP6 to reduce cellular metabolic activity in both PC3 and DU145 AIPCa cell lines. This effect of combined treatment on mitochondrial depolarisation is particularly striking and is also reproduced by another proteasome inhibitor (ALLN). The enhanced effect of combined MG132/IP6 treatment is almost completely inhibited by cycloheximide and correlates with changes in BCL-2 family protein levels. Altogether these results suggest a role for BCL-2 family proteins in mediating the combined effect of IP6 and proteasome inhibitors and warrant further pre-clinical studies for the treatment of AIPCa.

The need for a multi-level biochemical approach to defeat cancer that will also support the host

Cited research papers support the main hypothesis that selected publications supply sufficient information for a combined multi-level treatment strategy against cancer that will also strengthen the host. The three major elements of the proposal are: (A) metastasis being separate from tumor growth requires specific antimetastatic treatments. For this, manipulation of the composition of phospholipids will alter cellular charge characteristics which are instrumental in adhesion. (B) Formate metabolism is at the center of many activities that are controlling tumor growth. The rational and consequences of this are as follows. Supply of formate depends mainly on serine, and consumption on conversion to CO2 yielding needed NADPH. The remainder is used to complete IMP configuration with 5-aminoimidazole-4-carboxamide ribonucleotide (ZMP). At homeostasis residual ZMP activates AMP-activated protein kinase (AMPK) to curb growth promoting phosphatidylinositol-3-kinase (PI3PK). Residual ZMP also activates the oxidation of choline to betaine supplying methyl groups needed for global methylation of DNA while increased oxidation of choline also alters cellular phospholipid composition (refer to metastasis). At low formate level, increased accumulated ZMP becomes pyrophosporylated to ZTP. AMPK activation shifts to PI3PK activity for insulin action restoring formate supplied by serine derived from glycolysis. Increased NADPH-generating glucose-6-phosphate dehydrogenase is diminishing NADP+ required for dehydrogenation of formate. This is restoring the formate balance while lowering ZMP levels to that of homeostasis. Evidence suggests that transformed cells exceed up-regulation of formate thus suppressing all ZMP accumulations resulting in limited AMPK activation, cessation of choline oxidation to betaine and loss of global methylation of DNA. This scenario appears to be tied to tumor survival, a state that could be altered by metabolic interventions using mild agents as described in the research reports cited. (C) Because of a preponderance of pyrimidines in cancer supporting UTP requiring immune evasion, exogenous IMP may offset this imbalance and thus hinder tumor anti-immune activities while strengthen host immune functions. For studies to confirm the proposal, the overall expected result is that a combined administration of all these agents cited here will outperform any single agent considered so far for anticancer treatment.

Chemopreventive efficacy of inositol hexaphosphate against prostate tumor growth and progression in TRAMP mice

PURPOSE

Herein, for the first time, we evaluated the in vivo chemopreventive efficacy of inositol hexaphosphate (IP6), a major constituent of high-fiber diets, against prostate tumor growth and progression in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model.

EXPERIMENTAL DESIGN

Beginning at 4 weeks of age, male TRAMP mice were fed 2% (w/v) IP6 in drinking water or only drinking water till 24 weeks of age, and then sacrificed. Prostate tissue was subjected to histopathologic analysis and to immunohistochemical analyses for proliferation and apoptosis.

RESULTS

IP6 feeding did not show any adverse effect on fluid and diet consumption and body weight. There was a significant reduction (40%; P < 0.01) in lower urogenital tract weight in IP6-fed mice. IP6 inhibited prostate cancer progression at prostatic intraepithelial neoplasia stage and strongly reduced the incidence of adenocarcinoma (prostatic intraepithelial neoplasia/adenocarcinoma, 75:25% in the IP6 group versus 39:61% in the control group; P < 0.05). The incidences of well-differentiated and poorly differentiated adenocarcinomas in the IP6-fed group were reduced by 44% and 62%, respectively. Immunohistochemical analysis of prostate tissue showed a 26% decrease (P < 0.05) in proliferation cell nuclear antigen-positive cells and a 3.5-fold increase in apoptotic cells with no effect on Tag expression by IP6.

CONCLUSIONS

These findings are both novel and highly significant in establishing for the first time that oral IP6, without any toxicity, suppresses prostate tumor growth and progression at the neoplastic stage, thereby reducing the incidence of adenocarcinoma through its antiproliferative and proapoptotic effects, and thus indicating that IP6 could have potential chemopreventive effects against human prostate cancer.

Phytochemicals for health, the role of pulses

Pulses are the seeds of legumes that are used for human consumption and include peas, beans, lentils, chickpeas, and fava beans. Pulses are an important source of macronutrients, containing almost twice the amount of protein compared to cereal grains. In addition to being a source of macronutrients and minerals, pulses also contain plant secondary metabolites that are increasingly being recognised for their potential benefits for human health. The best-studied legume is the soybean, traditionally regarded as an oilseed crop rather than a pulse. The potential health benefits of soy, particularly with respect to isoflavone content, have been the subject of much research and the focus of several reviews. By comparison, less is known about pulses. This review investigates the health potential of pulses, examining the bioactivity of pulse isoflavones, phytosterols, resistant starch, bioactive carbohydrates, alkaloids and saponins. The evidence for health properties is considered, as is the effect of processing and cooking on these potentially beneficial phytochemicals.

Apoptotic effect of IP(6) was not enhanced by co-treatment with myo-inositol in prostate carcinoma PC3 cells

Inositol hexaphosphate (IP(6)) is a major constituent of most cereals, legumes, nuts, oil seeds and soybean. Previous studies reported the anticancer effect of IP(6) and suggested that co-treatment of IP(6) with inositol may enhance anticancer effect of IP(6). Although the anticancer effect of IP(6) has been intensively studied, the combinational effect of IP(6) and inositol and involved mechanisms are not well understood so far. In the present study, we investigated the effect of IP(6) and myo-inositol (MI) on cell cycle regulation and apoptosis using PC3 prostate cancer cell lines. When cells were co-treated with IP(6) and MI, the extent of cell growth inhibition was significantly increased than that by IP(6) alone. To identify the effect of IP(6) and MI on apoptosis, the activity of caspase-3 was measured. The caspase-3 activity was significantly increased when cells were treated with either IP(6) alone or both IP(6) and MI, with no significant enhancement by co-treatment. To investigate the effect of IP(6) and MI of cell cycle arrest, we measured p21 mRNA expression in PC3 cells and observed significant increase in p21 mRNA by IP(6). But synergistic regulation by co-treatment with IP(6) and MI was not observed. In addition, there was no significant effect by co-treatment compared to IP(6) treatment on the regulation of cell cycle progression although IP(6) significantly changed cell cycle distribution in the presence of MI or not. Therefore, these findings support that IP(6) has anticancer function by induction of apoptosis and regulation of cell cycle. However, synergistic effect by MI on cell cycle regulation and apoptosis was not observed in PC3 prostate cancer cells.

Unique formosan mushroom Antrodia camphorata differentially inhibits androgen-responsive LNCaP and -independent PC-3 prostate cancer cells

Antrodia camphorata (AC), a precious and unique folkloric medicinal mushroom enriched in polyphenolics, isoflavonoids, triterpenoids, and polysaccharides, has been diversely used in Formosa (Taiwan) since the 18th century. In this study, prostate cancer (PCa) cell lines PC-3 (androgen independent) and LNCaP (androgen responsive) were treated with AC crude extract (ACCE) at 50-200 microg/mL, respectively, for 48 h. At the minimum effective dose 150 microg/mL, LNCaP showed a G1/S phase arrest with significant apoptosis. Such dose-dependent behavior of LNCaP cells in response to ACCE was confirmed to proceed as Akt-->p53-->p21-->CDK4/cyclin D1-->G1/S-phase arrest-->apoptosis, which involved inhibiting cyclin D1 activity and preventing pRb phosphorylation. In contrast, being without p53, PC-3 cells showed a G2/M-phase arrest mediated through pathway p21-->cyclin B1/Cdc2-->G2/M-phase arrest, however, with limited degree of apoptosis, implicating that ACCE is able to differentially inhibit the growth of different PCa cells by modulating different cell cycle signaling pathways. We conclude that this unique Formosan mushroom, A. camphorata, due to its nontoxicity, might be used as a good adjuvant anticancer therapy for prostate cancers despite its androgen-responsive behaviors, which has long been a serious drawback often encountered clinically in hormonal refractory cases treated by antihormonal therapies and chemotherapeutics.

Molecular mechanism of inositol hexaphosphate-mediated apoptosis in human malignant glioblastoma T98G cells

Glioblastoma is the deadliest brain tumor in humans. Current therapies are mostly ineffective and new agents need to be explored for controlling this devastating disease. Inositol hexaphosphate (IP6) is a phytochemical that is widely found in corns, cereals, nuts, and high fiber-content foods. Previous studies demonstrated anti-cancer properties of IP6 in several in vitro and in vivo tumor models. However, therapeutic efficacy of IP6 has not yet been evaluated in glioblastoma. Here, we explored the molecular mechanism of action of IP6 in human malignant glioblastoma T98G cells. The viability of T98G cells decreased following treatment with increasing doses of IP6. T98G cells exposed to 0.25, 0.5, and 1 mM IP6 for 24 h showed morphological and biochemical features of apoptosis. Western blotting indicated changes in expression of Bax and Bcl-2 proteins resulting in an increase in Bax:Bcl-2 ratio and upregulation of cytosolic levels of cytochrome c and Smac/Diablo, suggesting involvement of mitochondria-dependent caspase cascade in apoptosis. IP6 downregulated cell survival factors such as baculovirus inhibitor-of-apoptosis repeat containing-2 (BIRC-2) protein and telomerase to promote apoptosis. Upregulation of calpain and caspase-9 occurred in course of apoptosis. Increased activities of calpain and caspase-3 cleaved 270 kD alpha-spectrin at specific sites generating 145 kD spectrin break down product (SBDP) and 120 kD SBDP, respectively. Increased caspase-3 activity also cleaved inhibitor of caspase-3-activated DNase and poly(ADP-ribose) polymerase. Collectively, our results demonstrated that IP6 down regulated the survival factors BIRC-2 and telomerase and upregulated calpain and caspase-3 activities for apoptosis in T98G cells.

Dactylone Inhibits Epidermal Growth Factor–Induced Transformation and Phenotype Expression of Human Cancer Cells and Induces G1-S Arrest and Apoptosis

The marine natural chamigrane-type sesquiterpenoid, dactylone, is closely related to secondary metabolites of some edible species of red algae. In the present study, the effect of dactylone was tested on the mouse skin epidermal JB6 P+ Cl41 cell line and its stable transfectants as well as on several human tumor cell lines, including lung (H460), colon (HCT-116), and skin melanomas (SK-MEL-5 and SK-MEL-28). This natural product was effective at nontoxic doses as a cancer-preventive agent, which exerted its actions, at least in part, through the inhibition of cyclin D3 and Cdk4 expression and retinoblastoma tumor suppressor protein (Rb) phosphorylation. The inhibition of these cell cycle components was followed by cell cycle arrest at the G1-S transition with subsequent p53-independent apoptosis. Therefore, these data showed that application of dactylone and related compounds may lead to decreased malignant cell transformation and/or decreased tumor cell proliferation.

Protection against cancer by dietary IP6 and inositol

Inositol hexaphosphate (IP(6)) is a naturally occurring polyphosphorylated carbohydrate, abundantly present in many plant sources and in certain high-fiber diets, such as cereals and legumes. In addition to being found in plants, IP(6) is contained in almost all mammalian cells, although in much smaller amounts, where it is important in regulating vital cellular functions such as signal transduction, cell proliferation, and differentiation. For a long time IP(6) has been recognized as a natural antioxidant. Recently IP(6) has received much attention for its role in cancer prevention and control of experimental tumor growth, progression, and metastasis. In addition, IP(6) possesses other significant benefits for human health, such as the ability to enhance immune system, prevent pathological calcification and kidney stone formation, lower elevated serum cholesterol, and reduce pathological platelet activity. In this review we show the efficacy and discuss some of the molecular mechanisms that govern the action of this dietary agent. Exogenously administered IP(6) is rapidly taken up into cells and dephosphorylated to lower inositol phosphates, which further affect signal transduction pathways resulting in cell cycle arrest. A striking anticancer action of IP(6) was demonstrated in different experimental models. In addition to reducing cell proliferation, IP(6) also induces differentiation of malignant cells. Enhanced immunity and antioxidant properties also contribute to tumor cell destruction. Preliminary studies in humans show that IP(6) and inositol, the precursor molecule of IP(6), appear to enhance the anticancer effect of conventional chemotherapy, control cancer metastases, and improve quality of life. Because it is abundantly present in regular diet, efficiently absorbed from the gastrointestinal tract, and safe, IP(6) + inositol holds great promise in our strategies for cancer prevention and therapy. There is clearly enough evidence to justify the initiation of full-scale clinical trials in humans.