Protection against oxidative DNA damage and stress in human prostate by glutathione S-transferase P1

Loss of the stress sensor GADD45A promotes stem cell activity and ferroptosis resistance in LGR4/HOXA9-dependent AML

ABSTRACT

The overall prognosis of acute myeloid leukemia (AML) remains dismal, largely because of the inability of current therapies to kill leukemia stem cells (LSCs) with intrinsic resistance. Loss of the stress sensor growth arrest and DNA damage-inducible 45 alpha (GADD45A) is implicated in poor clinical outcomes, but its role in LSCs and AML pathogenesis is unknown. Here, we define GADD45A as a key downstream target of G protein-coupled receptor (LGR)4 pathway and discover a regulatory role for GADD45A loss in promoting leukemia-initiating activity and oxidative resistance in LGR4/HOXA9-dependent AML, a poor prognosis subset of leukemia. Knockout of GADD45A enhances AML progression in murine and patient-derived xenograft (PDX) mouse models. Deletion of GADD45A induces substantial mutations, increases LSC self-renewal and stemness in vivo, and reduces levels of reactive oxygen species (ROS), accompanied by a decreased response to ROS-associated genotoxic agents (eg, ferroptosis inducer RSL3) and acquisition of an increasingly aggressive phenotype on serial transplantation in mice. Our single-cell cellular indexing of transcriptomes and epitopes by sequencing analysis on patient-derived LSCs in PDX mice and subsequent functional studies in murine LSCs and primary AML patient cells show that loss of GADD45A is associated with resistance to ferroptosis (an iron-dependent oxidative cell death caused by ROS accumulation) through aberrant activation of antioxidant pathways related to iron and ROS detoxification, such as FTH1 and PRDX1, upregulation of which correlates with unfavorable outcomes in patients with AML. These results reveal a therapy resistance mechanism contributing to poor prognosis and support a role for GADD45A loss as a critical step for leukemia-initiating activity and as a target to overcome resistance in aggressive leukemia.

Cellular Factors Involved in the Hepatitis D Virus Life Cycle

Hepatitis D virus (HDV) is a defective RNA virus with a negative-strand RNA genome encompassing less than 1700 nucleotides. The HDV genome encodes only for one protein, the hepatitis delta antigen (HDAg), which exists in two forms acting as nucleoproteins. HDV depends on the envelope proteins of the hepatitis B virus as a helper virus for packaging its ribonucleoprotein complex (RNP). HDV is considered the causative agent for the most severe form of viral hepatitis leading to liver fibrosis/cirrhosis and hepatocellular carcinoma. Many steps of the life cycle of HDV are still enigmatic. This review gives an overview of the complete life cycle of HDV and identifies gaps in knowledge. The focus is on the description of cellular factors being involved in the life cycle of HDV and the deregulation of cellular pathways by HDV with respect to their relevance for viral replication, morphogenesis and HDV-associated pathogenesis. Moreover, recent progress in antiviral strategies targeting cellular structures is summarized in this article.

Molecular Docking Studies and the Effect of Fluorophenylthiourea Derivatives on Glutathione-Dependent Enzymes

Cancer is a serious problem affecting the health of all human societies. Chemotherapy refers to the use of drugs to kill cancer or the origin of cancer. In the past three decades, researchers have studied about proteins and their roles in the production of cancer cells. Glutathione S-transferases (GSTs) are a superfamily of enzymes that play a key role in cellular detoxification, protecting against reactive electrophiles attacks, including chemotherapeutic agents. Glutathione reductase (GR) is an important antioxidant enzyme involved in protecting the cell against oxidative stress. In this current study, GST and GR enzymes were purified from human erythrocytes using affinity chromatography. GR was obtained with a specific activity of 5.95 EU/mg protein and a 52.38 % yield. GST was obtained with a specific activity of 4.88 EU/mg protein and a 74.88 % yield. The effect of fluorophenylthiourea derivatives on the purified enzymes was investigated. Afterward, K_I values were found to range from 23.04±4.37 μM-59.97±13.45 μM for GR and 7.22±1.64 μM-41.24±2.55 μM for GST. 1-(2,6-difluorophenyl)thiourea was showed the best inhibition effect for both GST and GR enzymes. The relationships of inhibitors with 3D structures of GST and GR were explained by molecular docking studies.

The role of drug-metabolizing enzymes in synthetic lethality of cancer

Drug-metabolizing enzymes (DMEs) have shown increasing importance in anticancer therapy. It is not only due to their effect on activation or deactivation of anticancer drugs, but also because of their extensive connections with pathological and biochemistry changes during tumorigenesis. Meanwhile, it has become more accessible to discovery anticancer drugs that selectively targeted cancer cells with the development of synthetic lethal screen technology. Synthetic lethal strategy makes use of unique genetic markers that different cancer cells from normal tissues to discovery anticancer agents. Dysregulation of DMEs has been found in various cancers, making them promising candidates for synthetic lethal strategy. In this review, we will systematically discuss about the role of DMEs in tumor progression, the application of synthetic lethality strategy in drug discovery, and a link between DMEs and synthetic lethal of cancer.

Epigenetic factors in breast cancer therapy

Epigenetic modifications are inherited differences in cellular phenotypes, such as cell gene expression alterations, that occur during somatic cell divisions (also, in rare circumstances, in germ line transmission), but no alterations to the DNA sequence are involved. Histone alterations, polycomb/trithorax associated proteins, short non-coding or short RNAs, long non—coding RNAs (lncRNAs), & DNA methylation are just a few biological processes involved in epigenetic events. These various modifications are intricately linked. The transcriptional potential of genes is closely conditioned by epigenetic control, which is crucial in normal growth and development. Epigenetic mechanisms transmit genomic adaptation to an environment, resulting in a specific phenotype. The purpose of this systematic review is to glance at the roles of Estrogen signalling, polycomb/trithorax associated proteins, DNA methylation in breast cancer progression, as well as epigenetic mechanisms in breast cancer therapy, with an emphasis on functionality, regulatory factors, therapeutic value, and future challenges.

Radioresistance in Prostate Cancer: Focus on the Interplay between NF-κB and SOD

Prostate cancer occurs frequently in men and can often lead to death. Many cancers, including prostate cancer, can be initiated by oxidative insult caused by free radicals and reactive oxygen species. The superoxide dismutase family removes the oxygen-derived reactive oxygen species, and increased superoxide dismutase activity can often be protective against prostate cancer. Prostate cancer can be treated in a variety of ways, including surgery, androgen deprivation therapy, radiation therapy, and chemotherapy. The clinical trajectory of prostate cancer varies from patient to patient, but more aggressive tumors often tend to be radioresistant. This is often due to the free-radical and reactive-oxygen-species-neutralizing effects of the superoxide dismutase family. Superoxide dismutase 2, which is especially important in this regard, can be induced by the NF-κB pathway, which is an important mechanism in radioresistance. This information has enabled the development of interventions that manipulate the NF-κB mechanism to treat prostate cancer.

Combination of trehalose and low boron in presence of decreased glycerol improves post-thawed ram sperm parameters: A model study in boron research

BACKGROUND

Sperm cryopreservation has been widely used in the field of reproductive biotechnology. It applies to certain males of economic and scientific values, including livestock breeds or endangered animal species. The development of a semen extender with a low cryoprotectant concentration and an appropriate amount of trehalose and boron can prevent the deterioration of sperm parameters.

OBJECTIVE

The main goal of this study is to establish a suitable ram extender model, by examining different combinations of high (5%) and low (3%) glycerol concentrations (to reduce its toxic effects on sperm freezing), a fixed amount of trehalose and an increased dose of boron to prevent the deterioration of sperm parameters, and investigate the levels of gene expressions.

MATERIALS AND METHODS

The Merino ram ejaculates were collected. The collected ejaculates providing the defined criteria were pooled. The pooled ejaculates were divided into eight aliquots and diluted with the Tris extender including different combinations of glycerol (5% and 3%) and boron (0.25, 0.5, and 1 mm) concentrations and a fixed amount of trehalose, then frozen. After freeze-thawing process, sperm motility, mitochondrial membrane activity, plasma membrane integrity, acrosomal membrane integrity, DNA damage (single cell gel electrophoresis (COMET) and TUNEL assays) as well as NAD(P)H quinone oxyreductase (NQO1), glutamate-cycteine ligase (GCLC), and glutathione S-transferase (GSTP1) for molecular mechanisms of sperm cell response to oxidative stress were assessed for different extender groups following freeze-thawing process: 5% glycerol + 0 mm boron (G5B0.00), 5% glycerol + 0.25 mm boron (G5B0.25), 5% glycerol + 0.5 mm boron (G5B0.50), 5% glycerol + 1 mm boron (G5B1.00), 3% glycerol + 0 mm boron (G3B.00), 3% glycerol + 0.25 mm boron (G3B0.25), 3% glycerol + 0.5 mm boron (G3B0.50), and 3% glycerol + 1 mm boron (G3B1.00).

RESULTS

G3B0.25 presented higher percentages of subjective motility, mitochondrial activity, and viability of spermatozoa comparing with G5B0.00 and groups with boron. Supplementation of 0.25 mm boron with and without trehalose (G3B0.25 and G5B0.25) showed higher acrosome integrity, compared with G5B0.00, G5B1.00, G3B0.50, and G3B1.00. For TUNEL analysis, G3B1.00 showed the highest DNA integrity among the experimental groups which was statistically significant only with G5B0.50 (p < 0.05). The mRNA levels of NQO1 were significantly decreased in G5B1.00, G3B0.50, and G3B1.00, when compared to G5B0.00. In comparison with G5B0.00, supplementation of 1 mm boron with and without trehalose had significantly lower expression of GCLC. The level of GSTP1 gene was significantly lower (approximately threefold) in G3B1.00, compared to G5B0.00 (p < 0.05).

DISCUSSION AND CONCLUSION

It can be assumed that the increase of the boron concentration in the extender may have important adverse effects on sperm parameters and antioxidant gene expression after thawing. The results obtained from this study will help to understand the toxicity limits of boron and eliminate the toxicity of glycerol in studies of gametes and tissue freezing. Therefore, it can be concluded that the use of sufficient boron can decrease cryodamages of cryopreservation of mammalian spermatozoa as well tissue engineering.

Adaptive responses to air pollution in human dermal fibroblasts and their potential roles in aging

The damaging effects of air pollution on the skin are becoming increasingly researched and the outcomes of this research are now a major influence in the selection and development of protective ingredients for skincare formulations. However, extensive research has not yet been conducted into the specific cellular defense systems that are being affected after exposure to such pollutants. Research investigating the affected systems is integral to the development of suitable interventions that are capable of augmenting the systems most impacted by air pollutant exposure. The following studies involved exposing primary human dermal fibroblasts to different concentrations of particulate matter and analyzing its effects on mitochondrial complex activity, nuclear factor erythroid 2-related factor 2 localization using immunocytochemistry and protein expression of electron transport chain complex proteins, sirtuin-1 (SIRT1), and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) using western blotting. Particulate matter-induced alterations in both mitochondrial complex protein and activity, indicating oxidative stress, which was also complimented by increased expression of antioxidant proteins GSTP1/2 and SOD2. Particulate matter also seemed to modify expression of the proteins SIRT1 and PGC-1α which are heavily involved in the regulation of mitochondrial biogenesis and energy metabolism. Given the reported results indicating that particulate matter induces damage through oxidative stress and has a profound effect on mitochondrial homeostasis, interventions involving targeted mitochondrial antioxidants may help to minimize the damaging downstream effects of pollutant-induced oxidative stress originating from the mitochondria.

Novel Prostate Cancer Biomarkers: Aetiology, Clinical Performance and Sensing Applications

The review initially provides a short introduction to prostate cancer (PCa) incidence, mortality, and diagnostics. Next, the need for novel biomarkers for PCa diagnostics is briefly discussed. The core of the review provides details about PCa aetiology, alternative biomarkers available for PCa diagnostics besides prostate specific antigen and their biosensing. In particular, low molecular mass biomolecules (ions and metabolites) and high molecular mass biomolecules (proteins, RNA, DNA, glycoproteins, enzymes) are discussed, along with clinical performance parameters.

Low expression of GSTP1 in the aqueous humour of patients with primary open-angle glaucoma

Primary open‐angle glaucoma (POAG) is characterized by irreversible neurodegeneration accompanied by visual field defects and high intraocular pressure. Currently, an effective treatment is not available to prevent the progression of POAG, other than treatments to decrease the high intraocular pressure. We performed proteomic analysis of aqueous humour (AH) samples from patients with POAG combined with cataract and patients with cataract to obtain a better understanding of the pathogenesis of POAG and explore potential treatment targets for this condition. Samples were collected from 10 patients with POAG combined with cataract and 10 patients with cataract. Samples from each group were pooled. A high‐resolution, label‐free, liquid chromatography‐tandem mass spectrometry‐based quantitative proteomic analysis was performed. In total, 610 proteins were identified in human AH samples from the two groups. A total of 48 up‐regulated proteins and 49 down‐regulated proteins were identified in the POAG combined with cataract group compared with the control group. Gene Ontology (GO) analysis revealed key roles for these proteins in inflammation, immune responses, growth and development, cellular movement and vesicle‐mediated transport in the biological process category. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated the down‐regulated expression of glutathione S‐transferase P (GSTP1) in the glutathione metabolism signalling pathway in the POAG combined with cataract group. Additionally, certain significantly differentially expressed proteins in the proteomic profile were verified by enzyme‐linked immunosorbent assay (ELISA). GSTP1 levels were reduced in the human AH samples from the POAG combined with cataract group, based on the results of ELISA and proteomic profiling. Therefore, GSTP1, a redox‐related marker, may be involved in the pathological process of POAG and may become a treatment target in the future.

Combination of fetuin and trehalose in presence of low glycerol has beneficial effects on freeze-thawed ram spermatozoa

BACKGROUND

Freeze-thawing process negatively affects ram spermatozoa in terms of sperm quality, DNA integrity and antioxidant defence system. Thus, antioxidant supplementation of spermatozoa during freeze-thawing is suggested to improve sperm parameters.

OBJECTIVES

The aim of this study was to determine the effects of fetuin and trehalose added into ram semen extender on sperm parameters, antioxidant parameters, antioxidant-related gene expressions and DNA integrity during the freeze-thawing process, in low glycerol concentration.

METHODS

Semen samples collected from six mature rams were pooled and splitted into equal aliquots and diluted with a tris-based extender containing different concentrations of glycerol (G5; %5 and G3; %3), fetuin (F; 2.5, 5 and 15 mg/mL) and trehalose (60 mm) as eight groups (G5F0, G5F2.5, G5F5, G5F15, G3F0, G3F2.5, G3F5 and G3F15).

RESULTS

G3F5 group resulted in the highest motility, mitochondrial activity and viability and the lowest DNA fragmentation and DNA damage (p < 0.05). Also, G3F0 displayed considerably more cryoprotective effect compared with G5F0 group (p < 0.05) in terms of motility, mitochondrial activity and viability rates. Lipid peroxidation levels decreased in G5F5 group compared with G5F0 group (p < 0.05). The levels of total glutathione increased in G3F2.5 group (p < 0.05) in comparison with the G5F0 group. NQO1 gene levels were upregulated approximately twofold in G5F5, G5F15, G3F2.5, G3F5 and G3F15 groups compared with G5F0 group (p < 0.05). The levels of GCLC gene were approximately twofold higher in G3F0, G3F2.5, G3F5 and G3F15 groups compared with G5F0 group (p < 0.05). GSTP1 gene levels were significantly higher with different levels in all treatment groups except for G5F2.5 and G3F0 groups in comparison with G5F0 group (p < 0.05).

CONCLUSIONS

Co-supplementation of tris-based extender having low glycerol (3%) with trehalose and fetuin to enhance the quality of ram spermatozoa after freeze-thawing process is recommended.

Effect of Harvest Age on Total Phenolic, Total Anthocyanin Content, Bioactive Antioxidant Capacity and Antiproliferation of Black and White Glutinous Rice Sprouts

Black (cv. BGR) and white (cv. RD6) glutinous rice sprouts from fertilizer- and pesticide-free farm in Khon Kaen province, Thailand were investigated for antioxidation and antiproliferative activity. Three different ages of rice sprouts were collected and prepared as the extract. BGR exerted higher antioxidant capacity than RD6 based on total phenolic (TPC) and total anthocyanin contents (TAC), DPPH, and FRAP assays. BGR at 10–15 days contained the highest TPC (29.72 ± 1.42 mg gallic acid equivalent/g extract) and reducing power (2.22 ± 0.014 mmole FeSO4/g extract). BGR at 20–25 days contained the highest TAC (0.86 ± 0.096 equivalence of cyanidin-3-glucoside/g extract) and DPPH radical scavenging activity (IC50 = 231.09 ± 12.99 μg/mL). Antiproliferative activity of the extracts was evaluated in the human T-lymphocyte (Jurkat), hepatocellular carcinoma (HepG2), colorectal carcinoma (HCT116), melanoma (SK-MEL-2) and noncancerous cells (Vero) by neutral red assay. BGR showed the most selective antiproliferation against Jurkat cells, by inducing apoptosis, and caspase 3/7 activity. BGR at 200 μg/mL from all ages significantly decreased ROS using DCFH-DA and increased endogenous glutathione levels in Jurkat cells compared to the control (p < 0.05). The higher antiproliferation of BGR than RD6 was via its antioxidation capacity and attributed to its higher phenolic and anthocyanin contents. BGR sprout is a potential source of biologically active substances good for wellness and health benefits.

Decreasing glycerol content by co-supplementation of trehalose and taxifolin hydrate in ram semen extender: Microscopic, oxidative stress, and gene expression analyses

This study aimed to evaluate the comparative effects of taxifolin hydrate and trehalose on the quality of frozen-thawed ram spermatozoa for the first time. Ejaculates collected from six mature rams were pooled, and divided to eight equal aliquots to extend them with different concentrations of glycerol (%5 and %3), taxifolin hydrate (10, 100, and 500 μM), and trehalose (60 mM) as eight groups (G5T0, G5T10, G5T100, G5T500, G3T0, G3T10, G3T100, and G3T500). After freeze-thawing process of cryopreservation, microscopic and oxidative stress parameters, and gene expression levels were investigated for understanding of possible impacts of taxifolin hydrate and trehalose. The study showed that G3T10 resulted in the highest post-thawed viability and mitochondrial activity. Moreover, all extenders with taxifolin hydrate reduced DNA fragmentation in comparison to G5T0, but DNA damage was prevented at the highest rate in presence of G5T10. The level of LPO significantly decreased in the groups G5T500 and G3T100, and the expression levels of NQO1, GCLC, and GSTP1 genes significantly increased in the groups G5T100, G5T500, G3T10, and G3T100 compared to the group G5T0. Finally, co-supplementation of tris-based extender having 3% glycerol with 60 mM trehalose and 10 μM taxifolin hydrate in cryopreservation extender may be recommended to improve the quality of post-thawed ram spermatozoa. However, further in vivo and in vitro studies are suggested to evaluate fertility rates of frozen-thawed ram spermatozoa co-supplemented with trehalose and taxifolin hydrate.

Epigenetic Regulation of Differentially Expressed Drug-Metabolizing Enzymes in Cancer

Drug metabolism is a biotransformation process of drugs, catalyzed by drug-metabolizing enzymes (DMEs), including phase I DMEs and phase II DMEs. The aberrant expression of DMEs occurs in the different stages of cancer. It can contribute to the development of cancer and lead to individual variations in drug response by affecting the metabolic process of carcinogen and anticancer drugs. Apart from genetic polymorphisms, which we know the most about, current evidence indicates that epigenetic regulation is also central to the expression of DMEs. This review summarizes differentially expressed DMEs in cancer and related epigenetic changes, including DNA methylation, histone modification, and noncoding RNAs. Exploring the epigenetic regulation of differentially expressed DMEs can provide a basis for implementing individualized and rationalized medication. Meanwhile, it can promote the development of new biomarkers and targets for the diagnosis, treatment, and prognosis of cancer. SIGNIFICANCE STATEMENT: This review summarizes the aberrant expression of DMEs in cancer and the related epigenetic regulation of differentially expressed DMEs. Exploring the epigenetic regulatory mechanism of DMEs in cancer can help us to understand the role of DMEs in cancer progression and chemoresistance. Also, it provides a basis for developing new biomarkers and targets for the diagnosis, treatment, and prognosis of cancer.

Glutathione S-Transferase pi-1 Knockdown Reduces Pancreatic Ductal Adenocarcinoma Growth by Activating Oxidative Stress Response Pathways

Glutathione S-transferase pi-1 (GSTP1) plays an important role in regulating oxidative stress by conjugating glutathione to electrophiles. GSTP1 is overexpressed in breast, colon, lung, and prostate tumors, where it contributes to tumor progression and drug resistance; however, the role of GSTP1 in pancreatic ductal adenocarcinoma (PDAC) is not well understood. Using shRNA, we knocked down GSTP1 expression in three different PDAC cell lines and determined the effect on cell proliferation, cell cycle progression, and reactive oxygen species (ROS) levels. Our results show GSTP1 knockdown reduces PDAC cell growth, prolongs the G₀/G₁ phase, and elevates ROS in PDAC cells. Furthermore, GSTP1 knockdown results in the increased phosphorylation of c-Jun N-terminal kinase (JNK) and c-Jun and the decreased phosphorylation of extracellular signal-regulated kinase (ERK), p65, the reduced expression of specificity protein 1 (Sp1), and the increased expression of apoptosis-promoting genes. The addition of the antioxidant glutathione restored cell viability and returned protein expression levels to those found in control cells. Collectively, these data support the working hypothesis that the loss of GSTP1 elevates oxidative stress, which alters mitogen-activated protein (MAP) kinases and NF-κB signaling, and induces apoptosis. In support of these in vitro data, nude mice bearing orthotopically implanted GSTP1-knockdown PDAC cells showed an impressive reduction in the size and weight of tumors compared to the controls. Additionally, we observed reduced levels of Ki-67 and increased expression of cleaved caspase-3 in GSTP1-knockdown tumors, suggesting GSTP1 knockdown impedes proliferation and upregulates apoptosis in PDAC cells. Together, these results indicate that GSTP1 plays a significant role in PDAC cell growth and provides support for the pursuit of GSTP1 inhibitors as therapeutic agents for PDAC.

Effects of fermented rice bran on DEN-induced oxidative stress in mice: GSTP1, LINE-1 methylation, and telomere length ratio

N-diethylnitrosamine (DEN), a well-known carcinogen, not only induces excessive reactive oxygen species but also suppresses DNA methylation. This study investigated the effect of fermented rice bran (FRB) treatment on DEN-induced oxidative stress through DNA methylation and telomere length analysis. To evaluate the potential protective role of FRB in oxidative stress, two different doses of FRB, DEN, and their combination were administered to mice that were preadapted or not to FRB. Glutathione-S-transferase P1 (GSTP1) methylation levels significantly decreased at 2 and 24 hr after FRB and DEN co-administration in mice with and without pre-adaptation. Moreover, GSTP1 mRNA was upregulated under DEN-induced oxidative stress. Furthermore, changes in long interspersed nuclear element-1 methylation were observed from the viewpoint of genomic instability. In addition, FRB preadapted mice displayed a lower telomere length ratio than the non-adapted mice, suggesting that FRB adaptation offers advantages over the non-adapted conditions in terms of inflammation suppression. PRACTICAL APPLICATIONS: DEN induces excessive ROS, which is associated with oxidative stress on DNA and other cellular components, resulting in inflammation. This study shows that FRB may alleviate DEN-triggered oxidative stress, based on changes in GSTP1, LINE-1 methylation, and telomere length ratios, thereby, revealing the potential of dietary intervention during inflammation. Furthermore, this study furthers the current understanding of DNA methylation mechanisms underlying the antioxidant and anti-inflammatory effects of functional food components. These results indicate that dietary inclusion of FRB may help decrease oxidative DNA damage and its associated inflammation at early stages of a disease.

The Possibility of Preventive and Therapeutic Use of Green Tea Catechins in Prostate Cancer

BACKGROUND

Prostate cancer is one of the most frequent types of cancer. Despite the existence of various treatment strategies, treatment of prostate cancer still presents serious difficulties (especially in advanced stages). Polyphenols have been extensively assessed in terms of their potential use for prostate cancer treatment and prevention. Catechins are among the most well-known polyphenols in this respect.

OBJECTIVE

In this review, we summarize clinical study results concerning catechin applications with regard to prostate cancer treatment and prevention. We discuss some of the main mechanisms of the anticarcinogenic action of catechins.

CONCLUSION

The main mechanisms of the anticarcinogenic action of catechins are subdivided into two major types: (i) direct action on cancer cells and (ii) indirect effect based on catechins's impact on the microenvironment of cancer cells, particularly in relation to the immune system. At this level catechins might reduce tumor-associated inflammation and immune tolerance.

Oxidative Stress and Antioxidant Status in High-Risk Prostate Cancer Subjects

The oxidant/antioxidant balance has been implicated in the pathophysiology of prostate cancer. We investigated oxidative damage and antioxidant status in high-risk prostate cancer subjects. Reduced glutathione (GSH) levels were measured in erythrocytes, 8-hydroxydeoxyguanosine (8-OHdG) in leukocytes and plasma levels of catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GSH-R), glutathione S-transferase (GST), superoxide dismutase (SOD), and lipid peroxide products were measured in high-risk and age-matched healthy subjects. Serum PSA levels were significantly higher (p < 0.0001) in high-risk subjects, whereas GST (p < 0.0001) and GSH (p < 0.002) were higher in healthy controls. Levels of 8-OHdG, an oxidized nucleoside of DNA, were significantly increased (p < 0.0001) in high-risk subjects. No marked difference in the levels of CAT (p = 0.237), GSH-Px (p = 0.74), GSH-R (p = 0.344), SOD (p = 0.109), and lipid peroxide products (p = 0129) were observed between two groups. Pearson's correlation between GST and PSA (r = -0.69 (p < 0.0001)), GST and 8-OHdG (r = -0.62 (p < 0.0004)), GSH and 8-OHdG (r= -0.39 (p = 0.038)), and CAT and GSH-Px (r= -0.33 (p = 0.04)) were found to be negatively correlated, whereas 8-OHdG and PSA were positively associated (r= 0.57 (p < 0.002). These results indicate a significant role of oxidative damage in prostate carcinogenesis, particularly during the early stages of development. In conclusion, our data support the importance of antioxidant defense as a valuable diagnostic and/or prognostic marker in prostate cancer.

GSTP1 and cancer: Expression, methylation, polymorphisms and signaling (Review)

Glutathione S‑transferase Pi (GSTP1) is an isozyme encoded by the GST pi gene that plays an important regulatory role in detoxification, anti‑oxidative damage, and the occurrence of various diseases. The aim of the present study was to review the association between the expression of GSTP1 and the development and treatment of various cancers, and discuss GSTP1 methylation in several malignant tumors, such as prostate, breast and lung cancer, as well as hepatocellular carcinoma; to review the association between polymorphism of the GSTP1 gene and various diseases; and to review the effects of GSTP1 on electrophilic oxidative stress, cell signal transduction, and the regulation of carcinogenic factors. Collectively, GSTP1 plays a major role in the development of various diseases.

Early growth response 1 regulates hematopoietic support and proliferation in human primary bone marrow stromal cells

Human bone marrow stromal cells (BMSC) are key elements of the hematopoietic environment and they play a central role in bone and bone marrow physiology. However, how key stromal cell functions are regulated is largely unknown. We analyzed the role of the immediate early response transcription factor EGR1 as key stromal cell regulator and found that EGR1 was highly expressed in prospectively-isolated primary BMSC, down-regulated upon culture, and low in non-colony-forming CD45^neg stromal cells. Furthermore, EGR1 expression was lower in proliferative regenerating adult and fetal primary cells compared to adult steady-state BMSC. Overexpression of EGR1 in stromal cells induced potent hematopoietic stroma support as indicated by an increased production of transplantable CD34⁺CD90⁺ hematopoietic stem cells in expansion co-cultures. The improvement in bone marrow stroma support function was mediated by increased expression of hematopoietic supporting genes, such as VCAM1 and CCL28. Furthermore, EGR1 overexpression markedly decreased stromal cell proliferation whereas EGR1 knockdown caused the opposite effects. These findings thus show that EGR1 is a key stromal transcription factor with a dual role in regulating proliferation and hematopoietic stroma support function that is controlling a genetic program to co-ordinate the specific functions of BMSC in their different biological contexts.

Glutathione Transferase P1-1 an Enzyme Useful in Biomedicine and as Biomarker in Clinical Practice and in Environmental Pollution

Glutathione transferase P1-1 (GSTP1-1) is expressed in some human tissues and is abundant in mammalian erythrocytes (here termed e-GST). This enzyme is able to detoxify the cell from endogenous and exogenous toxic compounds by using glutathione (GSH) or by acting as a ligandin. This review collects studies that propose GSTP1-1 as a useful biomarker in different fields of application. The most relevant studies are focused on GSTP1-1 as a biosensor to detect blood toxicity in patients affected by kidney diseases. In fact, this detoxifying enzyme is over-expressed in erythrocytes when unusual amounts of toxins are present in the body. Here we review articles concerning the level of GST in chronic kidney disease patients, in maintenance hemodialysis patients and to assess dialysis adequacy. GST is also over-expressed in autoimmune disease like scleroderma, and in kidney transplant patients and it may be used to check the efficiency of transplanted kidneys. The involvement of GSTP in the oxidative stress and in other human pathologies like cancer, liver and neurodegenerative diseases, and psychiatric disorders is also reported. Promising applications of e-GST discussed in the present review are its use for monitoring human subjects living in polluted areas and mammals for veterinary purpose.

Nutrigenomics: Epigenetics and cancer prevention: A comprehensive review

Due to change in lifestyle and food habits, people are more at risk of diet-related diseases and cancers. It is also established that dietary modifications significantly reduce the risk of diseases. Nutrigenomics is relatively fresh discipline, but possess an enormous potential that can apply for prevention and management of certain carcinomas and diseases. This review enables us to generate useful information for scientists and health professionals regarding the role of Nutrigenomics in the prevention of diet and lifestyle-related diseases like cancer. It influences health conditions of individuals and susceptibility of disease by defining the metabolic response and gene expression. Epigenetic modifications can perform a significant role in disease occurrence and pathogenesis. DNA methylation and chromatin remodeling are the most common epigenetic mechanisms. Omega 3 fatty acids are the best example of nutrients and gene interaction not involving DNA methylation while certain bioactive food compounds have a proven role in cancer prevention through an epigenetic mechanism. Dietary polyphenols substantially take part in prevention of oral, breast, skin, esophageal, colorectal, prostate, pancreatic and lung cancers. Moreover, minerals and vitamins involve regulatory processes. Zinc, Selenium and folate involve in DNA repairing process have anticancer properties. Consumption of multivitamins prevents methylation of cancer cells.

NEAT1 paraspeckle promotes human hepatocellular carcinoma progression by strengthening IL-6/STAT3 signaling

The formation of paraspeckle, a stress-induced nuclear body, increases in response to viral infection or proinflammatory stimuli. Paraspeckle consists of lncRNA (nuclear paraspeckle assembly transcript 1, NEAT1) and protein components including NONO, SFPQ, PSPC1, etc., which are shown to be involved in viral infection and cancer. Both NEAT1 and NONO expression increase in human hepatocellular carcinoma (HCC) samples according to TCGA data. However, the role of paraspeckle in HCC progression needs further identification. IL-6 signaling is well known to contribute to HCC progression. Here we reported that IL-6 signaling increased paraspeckle formation in HCC cells. Destruction of paraspeckle formation by silencing the paraspeckle essential components NEAT1_2 or NONO could suppress IL-6-induced STAT3 phosphorylation in HCC cells, and consequently repressed IL-6-promoted in vitro HCC cell invasion, cell cycle progression and survival. Mechanistically, paraspeckle promotes IL-6-induced STAT3 phosphorylation by binding and trapping peroxiredoxin-5 (PRDX5) mRNA in nucleus, decreasing protein level of PRDX5 which can directly interact with STAT3 and inhibit STAT3 phosphorylation. Besides, glutathione S-transferase P (GSTP1) protein, which inhibits DNA damage and apoptosis through its detoxification and anti-oxidation function, was also trapped within paraspeckles under IL-6 stimulation. Paraspeckle-trapping of both PRDX5 mRNA and GSTP1 protein contributes to IL-6-increased DNA damage in HCC cells. Our results demonstrate that paraspeckle can nuclear entrap the inhibitors of IL-6/STAT3 signaling as well as DNA damage, and then strengthen the promoting effect on HCC progression by IL-6. Therefore, paraspeckle contributes to the inflammation-related HCC progression and might be a potential therapeutic target for HCC.

Oxidative stress marker 8-hydroxyguanosine is more highly expressed in prostate cancer than in benign prostatic hyperplasia

Oxidative stress is a primary cause of vascular endothelial damage. In the prostate, ischemia increases the levels of reactive oxygen species, growth factors and cytokines, and induces the development of angiogenesis, which results in cancer progression. The expression levels of an oxidative stress marker, 8-hydroxyguanosine (8-OHdG), were compared between prostate cancer and non-neoplastic prostate tissues. A prostate tissue microarray composed of 10 cases of prostatic adenocarcinoma and 70 cases of benign prostatic hyperplasia was immunohistochemically stained for 8-OHdG. All cases expressed 8-OHdG. The levels of 8-OHdG expression in prostatic cancer (30.0% moderate and 70.0% strong) were significantly higher than those in benign prostatic hyperplasia (71.4% moderate and 28.6% strong; (p<0.01). Notably, 8-OHdG is expressed more highly in prostate cancer tissues in comparison to benign prostate tissues.

The multifaceted role of glutathione S-transferases in cancer

Glutathione S-transferases (GSTs) are phase II detoxifying enzymes involved in the maintenance of cell integrity, oxidative stress and protection against DNA damage by catalyzing the conjugation of glutathione to a wide variety of electrophilic substrates. Though enzymes of the glutathione synthesis and salvage pathways have been well characterized in the past, there is still a lack of comprehensive understanding of their independent and coordinate regulatory mechanisms in carcinogenesis. The present review discusses implication of GST in cancer development and progression, gene polymorphism, drug resistance, signaling and epigenetic regulation involving their role in cancer. It is anticipated that GST especially the GSTP1 class can be developed as a biomarker either used alone or in combination with other biomarkers for early cancer detection and/or diagnosis as well as for future targeted preventive and therapeutic interventions with dietary agents.

Selenium-Dependent Antioxidant Enzymes: Actions and Properties of Selenoproteins

Unlike other essential trace elements that interact with proteins in the form of cofactors, selenium (Se) becomes co-translationally incorporated into the polypeptide chain as part of 21st naturally occurring amino acid, selenocysteine (Sec), encoded by the UGA codon. Any protein that includes Sec in its polypeptide chain is defined as selenoprotein. Members of the selenoproteins family exert various functions and their synthesis depends on specific cofactors and on dietary Se. The Se intake in productive animals such as chickens affect nutrient utilization, production performances, antioxidative status and responses of the immune system. Although several functions of selenoproteins are unknown, many disorders are related to alterations in selenoprotein expression or activity. Selenium insufficiency and polymorphisms or mutations in selenoproteins' genes and synthesis cofactors are involved in the pathophysiology of many diseases, including cardiovascular disorders, immune dysfunctions, cancer, muscle and bone disorders, endocrine functions and neurological disorders. Finally, heavy metal poisoning decreases mRNA levels of selenoproteins and increases mRNA levels of inflammatory factors, underlying the antagonistic effect of Se. This review is an update on Se dependent antioxidant enzymes, presenting the current state of the art and is focusing on results obtained mainly in chicken.

Influence of chronic inflammation on Bcl-2 and PCNA expression in prostate needle biopsy specimens

The association between inflammation and cancer has been established in certain forms of human malignancies; however, its role in prostate cancer remains unclear. The present study investigates a possible association between chronic inflammation and the development of epithelial neoplasia in the prostate. Needle biopsy specimens were obtained from patients with serum prostate-specific antigen levels >4 ng/ml, evaluated for morphological findings, and immunostained for Bcl-2 and proliferating cell nuclear antigen (PCNA). Bcl-2 is a survival protein that appears to lie at a nodal point in pathways involved in cell survival, carcinogenesis, and development of therapeutic resistance in certain cancer types. Similarly, PCNA is a critical protein for DNA replication, repair of DNA damage, chromatin structure maintenance, chromosome segregation and cell-cycle progression. The association between these two proteins was examined in prostate tissues with and without chronic inflammation, as well as tissues with and without evidence of neoplastic changes. Of the 106 needle biopsies examined, 18% exhibited atrophy with inflammation. Proliferative inflammatory atrophy/post-atrophic hyperplasia were observed in 42%, high-grade prostatic intraepithelial neoplasia (HGPIN) in 8%, prostatic adenocarcinoma in 11%, and 2% had atypical acinar proliferation suspicious for malignancy. A total of 36 specimens were stained for Bcl-2 and PCNA. Bcl-2 was expressed widely in inflammatory and epithelial tissue; however, more intense expression was observed in the areas of chronic inflammation, predominantly in infiltrating immune cells. The highest proliferation index was observed in the epithelia of HGPIN and cancer. An inverse correlation between the expression of Bcl-2 and the expression of PCNA was observed in the epithelium. The areas of chronic inflammation were associated with increased Bcl-2 expression, whereas the highly proliferative epithelium minimally expressed Bcl-2. These results suggest that Bcl-2 alters the phenotype of particular epithelial cells with a gain in neoplastic characteristics, leading to a likely precursor that may later progress into HGPIN and cancer.

Telomeres and telomerase in prostate cancer development and therapy

Aberrations in telomere biology are among the earliest events in prostate cancer tumorigenesis and continue during tumour progression. Substantial telomere shortening occurs in prostate cancer cells and high-grade prostatic intraepithelial neoplasia. Not all mechanisms of telomere shortening are understood, but oxidative stress from local inflammation might accelerate prostatic telomere loss. Critically short telomeres can drive the accumulation of tumour-promoting genomic alterations; however, continued telomere erosion is unsustainable and must be mitigated to ensure cancer cell survival and unlimited replication potential. Prostate cancers predominantly maintain telomeres by activating telomerase, but alternative mechanisms of telomere extension can occur in metastatic disease. Telomerase activity and telomere length assessment might be useful in prostate cancer diagnosis and prognosis. Telomere shortening in normal stromal cells has been associated with prostate cancer, whereas variable telomere lengths in prostate cancer cells and telomere shortening in cancer-associated stromal cells correlated with lethal disease. Single-agent telomerase-targeted treatments for solid cancers were ineffective in clinical trials but have not been investigated in prostate cancer and might be useful in combination with established regimens. Telomere-directed strategies have not been explored as extensively. Telomere deprotection strategies have the advantage of being effective in both telomerase-dependent and telomerase-independent cancers. Disruption of androgen receptor function in prostate cancer cells results in telomere dysfunction, indicating telomeres and telomerase as potential therapeutic targets in prostate cancer.

Green Tea Catechins for Prostate Cancer Prevention: Present Achievements and Future Challenges

Green tea catechins (GTCs) are a family of chemically related compounds usually classified as antioxidant molecules. Epidemiological evidences, supported by interventional studies, highlighted a more than promising role for GTCs in human prostate cancer (PCa) chemoprevention. In the last decades, many efforts have been made to gain new insights into the mechanism of action of GTCs. Now it is clear that GTCs' anticancer action can no longer be simplistically limited to their direct antioxidant/pro-oxidant properties. Recent contributions to the advancement of knowledge in this field have shown that GTCs specifically interact with cellular targets, including cell surface receptors, lipid rafts, and endoplasmic reticulum, modulate gene expression through direct effect on transcription factors or indirect epigenetic mechanisms, and interfere with intracellular proteostasis at various levels. Many of the effects observed in vitro are dose and cell context dependent and take place at concentrations that cannot be achieved in vivo. Poor intestinal absorption together with an extensive systemic and enteric metabolism influence GTCs' bioavailability through still poorly understood mechanisms. Recent efforts to develop delivery systems that increase GTCs' overall bioavailability, by means of biopolymeric nanoparticles, represent the main way to translate preclinical results in a real clinical scenario for PCa chemoprevention.

A perspective of chronic low exposure of arsenic on non-working women: Risk of hypertension

The relationship between arsenic (As) exposure and hypertension risk are extensively studied. The As content in scalp hair has been used as a reliable indicator of population for long-time exposure from different sources. Therefore, we investigated the association between hair As concentration and hypertension risk, as well as the potential modifying effects of single nucleotide polymorphisms (SNPs) related to phase II metabolism enzyme genes. We recruited 398 non-working women in Shanxi Province, northern China, from Aug 2012 to May 2013, including 163 subjects with hypertension (cases) and 235 healthy controls. Scalp hair and blood samples were collected from each subject. We analyzed the As concentrations of ~24-cm-long strands of hair representing the two most recent years of growth and SNPs of three genes (epoxide hydrolase 1, N-acetyltransferase 2, and glutathione S-transferase P1) in each subject. The results revealed that the hair As concentration of this population was significantly lower than in populations living near high As polluted sources in China and other countries. The median As concentration (inter-quartile range) of hair in the cases (i.e. 0.211 [0.114-0.395] μg/g hair) was higher than in the controls (i.e. 0.101 [0.048-0.227] μg/g hair). Higher hair As concentrations were associated with an elevated hypertension risk, with an adjusted odds ratio of 2.55 [95% confidence interval: 1.55-4.20]. No interaction effects between hair As concentration and SNPs related to phase II metabolism enzymes on hypertension risk were observed. It was concluded that chronic low exposure level of As might be associated with hypertension risk among the study subjects.

The importance of DNA methylation in prostate cancer development

After briefly reviewing the nature of DNA methylation, its general role in cancer and the tools available to interrogate it, we consider the literature surrounding DNA methylation as relating to prostate cancer. Specific consideration is given to recurrent alterations. A list of frequently reported genes is synthesized from 17 studies that have reported on methylation changes in malignant prostate tissue, and we chart the timing of those changes in the diseases history through amalgamation of several previously published data sets. We also review associations with genetic alterations and hormone signalling, before the practicalities of investigating prostate cancer methylation using cell lines are assessed. We conclude by outlining the interplay between DNA methylation and prostate cancer metabolism and their regulation by androgen receptor, with a specific discussion of the mitochondria and their associations with DNA methylation.

Oxidative stress in prostate hyperplasia and carcinogenesis

Prostatic hyperplasia (PH) is a common urologic disease that affects mostly elderly men. PH can be classified as benign prostatic hyperplasia (BPH), or prostate cancer (PCa) based on its severity. Oxidative stress (OS) is known to influence the activities of inflammatory mediators and other cellular processes involved in the initiation, promotion and progression of human neoplasms including prostate cancer. Scientific evidence also suggests that micronutrient supplementation may restore the antioxidant status and hence improve the clinical outcomes for patients with BPH and PCa. This review highlights the recent studies on prostate hyperplasia and carcinogenesis, and examines the role of OS on the molecular pathology of prostate cancer progression and treatment.

Catechins Variously Affect Activities of Conjugation Enzymes in Proliferating and Differentiated Caco-2 Cells

The knowledge of processes in intestinal cells is essential, as most xenobiotics come into contact with the small intestine first. Caco-2 cells are human colorectal adenocarcinoma that once differentiated, exhibit enterocyte-like characteristics. Our study compares activities and expressions of important conjugation enzymes and their modulation by green tea extract (GTE) and epigallocatechin gallate (EGCG) using both proliferating (P) and differentiated (D) caco-2 cells. The mRNA levels of the main conjugation enzymes were significantly elevated after the differentiation of Caco-2 cells. However, no increase in conjugation enzymes’ activities in differentiated cells was detected in comparison to proliferating ones. GTE/EGCG treatment did not affect the mRNA levels of any of the conjugation enzymes tested in either type of cells. Concerning conjugation enzymes activities, GTE/EGCG treatment elevated glutathione S-transferase (GST) activity by approx. 30% and inhibited catechol-O-methyltransferase (COMT) activity by approx. 20% in differentiated cells. On the other hand, GTE as well as EGCG treatment did not significantly affect the activities of conjugation enzymes in proliferating cells. Administration of GTE/EGCG mediated only mild changes of GST and COMT activities in enterocyte-like cells, indicating a low risk of GTE/EGCG interactions with concomitantly administered drugs. However, a considerable chemo-protective effect of GTE via the pronounced induction of detoxifying enzymes cannot be expected as well.

Association of indoor air pollution from coal combustion with influenza-like illness in housewives

An association of influenza-like illness (ILI) with outdoor air pollution has been reported. However, the effect of indoor air pollution on ILI was rarely investigated. We aimed to determine an association of indoor air pollution from coal combustion (IAPCC) and lifestyle with ILI risk in housewives, and the modification effect of phase II metabolic enzyme genes. We recruited 403 housewives for a cross-sectional study in Shanxi Province, China, including 135 with ILI frequency (≥1 time per year in the past ten years) as the case group and 268 with ILI frequency (<1 times per year) as the control group. Information on their energy usage characteristics and lifestyle was collected by questionnaires, as well as the single nucleotide polymorphisms (SNPs) of epoxide hydrolase 1 (rs1051740 and rs2234922), N-acetyltransferase 2 (rs1041983), and glutathione S-transferase (rs1695). We used exposure index to indicate the level of IAPCC among housewives. Our results revealed that the exposure index was positively correlated with ILI frequency. A significant dose-response trend between the exposure index and ILI risk was found with or without adjusting for confounders. Cooking frequency in kitchen with coal as primary fuel and ventilation frequency in the living room or bedroom with a coal-fueled stove for heating during the heating season were two important risk factors to affect ILI frequency. Only rs1051740 was found to be associated with exposure index, whereas it didn't have interaction effect with exposure index on ILI frequency. In conclusion, IAPCC and SNPs of rs1051740 were both associated with ILI frequency.

ROS and ROS-Mediated Cellular Signaling

It has long been recognized that an increase of reactive oxygen species (ROS) can modify the cell-signaling proteins and have functional consequences, which successively mediate pathological processes such as atherosclerosis, diabetes, unchecked growth, neurodegeneration, inflammation, and aging. While numerous articles have demonstrated the impacts of ROS on various signaling pathways and clarify the mechanism of action of cell-signaling proteins, their influence on the level of intracellular ROS, and their complex interactions among multiple ROS associated signaling pathways, the systemic summary is necessary. In this review paper, we particularly focus on the pattern of the generation and homeostasis of intracellular ROS, the mechanisms and targets of ROS impacting on cell-signaling proteins (NF-κB, MAPKs, Keap1-Nrf2-ARE, and PI3K-Akt), ion channels and transporters (Ca(2+) and mPTP), and modifying protein kinase and Ubiquitination/Proteasome System.

Cancer Risk and Eicosanoid Production: Interaction between the Protective Effect of Long Chain Omega-3 Polyunsaturated Fatty Acid Intake and Genotype

Dietary inclusion of fish and fish supplements as a means to improve cancer prognosis and prevent tumour growth is largely controversial. Long chain omega-3 polyunsaturated fatty acids (LCn-3 PUFA), eicosapentaenoic acid and docosahexaenoic acid, may modulate the production of inflammatory eicosanoids, thereby influencing local inflammatory status, which is important in cancer development. Although in vitro studies have demonstrated inhibition of tumour cell growth and proliferation by LCn-3 PUFA, results from human studies have been mainly inconsistent. Genes involved in the desaturation of fatty acids, as well as the genes encoding enzymes responsible for eicosanoid production, are known to be implicated in tumour development. This review discusses the current evidence for an interaction between genetic polymorphisms and dietary LCn-3 PUFA in the risk for breast, prostate and colorectal cancers, in regards to inflammation and eicosanoid synthesis.

A pilot study to investigate if New Zealand men with prostate cancer benefit from a Mediterranean-style diet

Carcinoma of the prostate is the most commonly diagnosed malignancy and the third leading cause of mortality in New Zealand men, making it a significant health issue in this country. Global distribution patterns suggest that diet and lifestyle factors may be linked to the development and progression of this cancer. Twenty men with diagnosed prostate cancer adhered to a Mediterranean diet, with specific adaptations, for three months. Prostate-specific antigen, C-reactive protein and DNA damage were evaluated at baseline and after three months of following the diet. Dietary data were collated from diet diaries and an adaptation of a validated Mediterranean diet questionnaire. A significant reduction in DNA damage compared to baseline was apparent, with particular benefit noted for overall adherence to the diet (p = 0.013), increased intake of folate (p = 0.023), vitamin C (p = 0.007), legumes (p = 0.004) and green tea (p = 0.002). Higher intakes of red meat and dairy products were inversely associated with DNA damage (p = 0.003 and p = 0.008 respectively). The results from this small feasibility study suggest that a high-antioxidant diet, modelled on Mediterranean traditions, may be of benefit for men with prostate cancer. Protection against DNA damage appears to be associated with the diet implemented, ostensibly due to reduction in reactive oxidant species. These findings warrant further exploration in a longer trial, with a larger cohort.

HES5 silencing is an early and recurrent change in prostate tumourigenesis

Prostate cancer is the most common cancer in men, resulting in over 10 000 deaths/year in the UK. Sequencing and copy number analysis of primary tumours has revealed heterogeneity within tumours and an absence of recurrent founder mutations, consistent with non-genetic disease initiating events. Using methylation profiling in a series of multi-focal prostate tumours, we identify promoter methylation of the transcription factor HES5 as an early event in prostate tumourigenesis. We confirm that this epigenetic alteration occurs in 86-97% of cases in two independent prostate cancer cohorts (n=49 and n=39 tumour-normal pairs). Treatment of prostate cancer cells with the demethylating agent 5-aza-2'-deoxycytidine increased HES5 expression and downregulated its transcriptional target HES6, consistent with functional silencing of the HES5 gene in prostate cancer. Finally, we identify and test a transcriptional module involving the AR, ERG, HES1 and HES6 and propose a model for the impact of HES5 silencing on tumourigenesis as a starting point for future functional studies.

MicroRNA Regulating Glutathione S-Transferase P1 in Prostate Cancer

Glutathione S-transferase P1 (GSTP1), an enzyme involved in detoxification process, is frequently inactivated in prostate cancer due to epigenetic modifications. Through in silico analysis we identified a subset of miRNAs that are putative targets in regulating GSTP1. miRNAs are small endogenous non-coding RNA that are critical regulators of various physiologic and pathologic processes and their level of expression may play a precise role in early diagnosis and prognosis of cancer. These small molecules have been detected in a wide variety of human biological specimens including blood, serum, urine, ejaculate and tissues, which could be utilized as clinically useful biomarker in early detection and prognosis of prostate cancer. The chapter summarizes the current knowledge about miRNA involved in GSTP1 regulation in prostate cancer and their potential as useful biomarkers of disease for early detection and prognosis, along with challenges and limitations in this development.

An investigation into the association between DNA damage and dietary fatty acid in men with prostate cancer

Prostate cancer is a growing problem in New Zealand and worldwide, as populations adopt a Western style dietary pattern. In particular, dietary fat is believed to be associated with oxidative stress, which in turn may be associated with cancer risk and development. In addition, DNA damage is associated with the risk of various cancers, and is regarded as an ideal biomarker for the assessment of the influence of foods on cancer. In the study presented here, 20 men with prostate cancer adhered to a modified Mediterranean style diet for three months. Dietary records, blood fatty acid levels, prostate specific antigen, C-reactive protein and DNA damage were assessed pre- and post-intervention. DNA damage was inversely correlated with dietary adherence (p = 0.013) and whole blood monounsaturated fatty acids (p = 0.009) and oleic acid (p = 0.020). DNA damage was positively correlated with the intake of dairy products (p = 0.043), red meat (p = 0.007) and whole blood omega-6 polyunsaturated fatty acids (p = 0.015). Both the source and type of dietary fat changed significantly over the course of the dietary intervention. Levels of DNA damage were correlated with various dietary fat sources and types of dietary fat.

Cytoprotective and regulatory functions of glutathione S-transferases in cancer cell proliferation and cell death

PURPOSE

Glutathione S-transferases (GSTs) family of enzymes is best known for their cytoprotective role and their involvement in the development of anticancer drug resistance. Recently, emergence of non-detoxifying properties of GSTs has provided them with significant biological importance. Addressing the complex interactions of GSTs with regulatory kinases will help in understanding its precise role in tumor pathophysiology and in designing GST-centered anticancer strategies.

METHODS

We reviewed all published literature addressing the detoxification and regulatory roles of GSTs in the altered biology of cancer and evaluating novel agents targeting GSTs for cancer therapy.

RESULTS

The role of GSTs, especially glutathione S-transferase P1 isoform in tumoral drug resistance, has been the cause of intense debate. GSTs have been demonstrated to interact with different protein partners and modulate signaling pathways that control cell proliferation, differentiation and apoptosis. These specific functions of GSTs could lead to the development of new therapeutic approaches and to the identification of some interesting candidates for preclinical and clinical development. This review focuses on the crucial role played by GSTs in the development of resistance to anticancer agents and the major findings regarding the different modes of action of GSTs to regulate cell signaling.

Regulation of epigenetic traits of the glutathione S-transferase P1 gene: from detoxification toward cancer prevention and diagnosis

Glutathione S-transferases (GSTs) are phase II drug detoxifying enzymes that play an essential role in the maintenance of cell integrity and protection against DNA damage by catalyzing the conjugation of glutathione to a wide variety of exo- and endogenous electrophilic substrates. Glutathione S-transferase P1 (GSTP1), the gene encoding the pi-class GST, is frequently inactivated by acquired somatic CpG island promoter hypermethylation in multiple cancer subtypes including prostate, breast, liver, and blood cancers. Epigenetically mediated GSTP1 silencing is associated with enhanced cancer susceptibility by decreasing its “caretaker” gene function, which tends to promote neoplastic transformation allowing cells to acquire additional alterations. Thus, this epigenetic alteration is now considered as a cancer biomarker but could as well play a driving role in multistep cancer development, especially well documented in prostate cancer development. The present review discusses applications of epigenetic alterations affecting GSTP1 in cancer medicine used alone or in combination with other biomarkers for cancer detection and diagnosis as well as for future targeted preventive and therapeutic interventions including by dietary agents.

Plant flavone apigenin binds to nucleic acid bases and reduces oxidative DNA damage in prostate epithelial cells

Oxidative stress has been linked to prostate carcinogenesis as human prostate tissue is vulnerable to oxidative DNA damage. Apigenin, a dietary plant flavone, possesses anti-proliferative and anticancer effects; however, its antioxidant properties have not been fully elucidated. We investigated sub-cellular distribution of apigenin, it's binding to DNA and protective effects against H2O2-induced DNA damage using transformed human prostate epithelial RWPE-1 cells and prostate cancer LNCaP, PC-3 and DU145 cells. Exposure of cells to apigenin exhibited higher accumulation in RWPE-1 and LNCaP cells, compared to PC-3 and DU145 cells. The kinetics of apigenin uptake in LNCaP cells was estimated with a Km value of 5 µmole/L and Vmax of 190 pmoles/million cells/h. Sub-cellular fractionation demonstrated that nuclear matrix retains the highest concentration of apigenin (45.3%), followed by cytosol (23.9%), nuclear membranes (17.9%) and microsomes (12.9%), respectively. Spectroscopic analysis of apigenin with calf-thymus DNA exhibited intercalation as the dominant binding mode to DNA duplex. Apigenin exposure resulted in significant genoprotective effects in H2O2-stressed RWPE-1 cells by reduction in reactive oxygen species levels. In addition, apigenin exposure suppressed the formation of 8-hydroxy-2' deoxyguanosine and protected exposed cells from apoptosis. Our studies demonstrate that apigenin is readily taken up by normal prostatic epithelial cells and prostate cancer cells, and is incorporated into their nuclei, where its intercalation with nucleic acid bases may account for its antioxidant and chemopreventive activities.