Increased ErbB-2 tyrosine kinase activity, MAPK phosphorylation, and cell proliferation in the prostate cancer cell line LNCaP following treatment by select pesticides

The toxicity and health risk of chlorothalonil to non-target animals and humans: A systematic review

Chlorothalonil (CTL), an organochloride fungicide applied for decades worldwide, has been found to be present in various matrixes and even accumulates in humans or other mammals through the food chain. Its high residue and diffusion in the environment have severely affected food security and public health. More and more research has considered CTL as a possible toxin to environmental non-target organisms, via influencing multiple systems such as metabolic, developmental, endocrine, genetic, and reproductive pathways. Aquatic organisms and amphibians are the most vulnerable species to CTL exposure, especially during the early period of development. Under experimental conditions, CTL can also have toxic effects on rodents and other non-target organisms. As for humans, CTL exposure is most often reported to be relevant to allergic reactions to the skin and eyes. We hope that this review will improve our understanding of the hazards and risks that CTL poses to non-target organisms and find a strategy for rational use.

Role of endocrine disruptors in male infertility and impact of COVID-19 on male reproduction

Several epidemiological studies suggest strong association of endocrine disruptors (EDs) with impaired male reproduction. High levels of polychlorinated biphenyls in serum are associated with low sperm count and poor fertility. A high dichloro diphenyl trichloroethane (DDT) concentration results in low serum testosterone (T) and poor semen quality. DDT stimulates estrogen production by acting as estrogen receptor agonist and potent androgen receptor antagonist. Phthalates, another group of EDs, induce seminiferous tubule degeneration with impaired spermatogenesis via disruption of gene expression that regulates cholesterol and lipid homeostasis resulting in low T. Bisphenol A, a strong exogenous estrogen with antiandrogen effect, lowers serum follicle-stimulating hormone, luteinizing hormone, and T, resulting in impaired development of seminiferous tubules and spermatogenesis. Di(2-ethylhexyl) phthalates can exert their antiandrogenic action by directly inhibiting testosterone biosynthesis via cytochrome P-450 dysfunction. Since these EDs are commonly found in plastic bottles, cosmetics, pesticides, some metal food cans, etc., and accumulate in the environment, it is very important to observe caution and avoid their exposure. This updated chapter also reviews the impact of COVID-19-related infection on male reproduction.

1,1,1-trichloro-2,2-bis (p-chlorophenyl)-ethane (DDT) and 1,1-Dichloro-2,2-bis (p, p'-chlorophenyl) ethylene (DDE) as endocrine disruptors in human and wildlife: A possible implication of mitochondria

1,1,1-trichloro-2,2-bis (p-chlorophenyl)-ethane (DDT) and its main metabolite 1,1-Dichloro-2,2-bis (p, p'-chlorophenyl) ethylene (DDE) act as endocrine disruptors in humans and wildlife. Immunomodulatory functions have also been attributed to both xenobiotics. DDT was banned in the 1970s due to its toxicity, but it is still produced and used for indoor residual spraying with disease vector control purposes. Due to their persistence and lipophilic properties, DDT and DDE can bioaccumulate through the food chain, being stored in organisms' adipose depots. Their endocrine disruptor function is mediated by agonist or antagonist interaction with nuclear receptors. Present review aimed to provide an overview of how DDT and DDE exposure impacts reproductive and immune systems with estrogen-disrupting action in humans and wildlife. Studies showing DDT and DDE impact on mitochondrial function and apoptosis pathway will also be reviewed, suggesting the hypothesis of direct action on mitochondrial steroid receptors.

Untangling the association between environmental endocrine disruptive chemicals and the etiology of male genitourinary cancers

Endocrine disrupting chemicals disrupt normal physiological function of endogenous hormones, their receptors, and signaling pathways of the endocrine system. Most endocrine disrupting chemicals exhibit estrogen/androgen agonistic and antagonistic activities that impinge upon hormone receptors and related pathways. Humans are exposed to endocrine disrupting chemicals through food, water and air, affecting the synthesis, release, transport, metabolism, binding, function and elimination of naturally occurring hormones. The urogenital organs function as sources of steroid hormones, are targeted end organs, and participate within systemic feedback loops within the endocrine system. The effects of endocrine disruptors can ultimately alter cellular homeostasis leading to a broad range of health effects, including malignancy. Human cancer is characterized by uncontrolled cell proliferation, mechanisms opposing cell-death, development of immortality, induction of angiogenesis, and promotion of invasion/metastasis. While hormonal malignancies of the male genitourinary organs are the second most common types of cancer, the molecular effects of endocrine disrupting chemicals in hormone-driven cancers has yet to be fully explored. In this commentary, we examine the molecular evidence for the involvement of endocrine disrupting chemicals in the genesis and progression of hormone-driven cancers in the prostate, testes, and bladder. We also report on challenges that have to be overcome to drive our understanding of these chemicals and explore the potential avenues of discovery that could ultimately allow the development of tools to prevent cancer in populations where exposure is inevitable.

Metabolic syndrome, endocrine disruptors and prostate cancer associations: biochemical and pathophysiological evidences

This review summarizes the main pathophysiological basis of the relationship between metabolic syndrome, endocrine disruptor exposure and prostate cancer that is the most common cancer among men in industrialized countries. Metabolic syndrome is a cluster of metabolic and hormonal factors having a central role in the initiation and recurrence of many western chronic diseases including hormonal-related cancers and it is considered as the worlds leading health problem in the coming years. Many biological factors correlate metabolic syndrome to prostate cancer and this review is aimed to focus, principally, on growth factors, cytokines, adipokines, central obesity, endocrine abnormalities and exposure to specific endocrine disruptors, a cluster of chemicals, to which we are daily exposed, with a hormone-like structure influencing oncogenes, tumor suppressors and proteins with a key role in metabolism, cell survival and chemo-resistance of prostate cancer cells. Finally, this review will analyze, from a molecular point of view, how specific foods could reduce the relative risk of incidence and recurrence of prostate cancer or inhibit the biological effects of endocrine disruptors on prostate cancer cells. On the basis of these considerations, prostate cancer remains a great health problem in terms of incidence and prevalence and interventional studies based on the treatment of metabolic syndrome in cancer patients, minimizing exposure to endocrine disruptors, could be a key point in the overall management of this disease.

Progress on Azadirachta indica Based Biopesticides in Replacing Synthetic Toxic Pesticides

Over the years, extensive use of commercially available synthetic pesticides against phytophagous insects has led to their bioaccumulation in the environment causing increased resistance and reduction in soil biodiversity. Further, 90% of the applied pesticides enter the various environmental resources as a result of run-off, exposing the farmers as well as consumers of the agricultural produce to severe health issues. Therefore, growing attention has been given toward the development of alternate environmentally friendly pesticides/insecticides that would aid an efficient pest management system and also prevent chronic exposures leading to diseases. One such strategy is, the use of neem plant's (Binomial name: Azadirachta indica) active ingredients which exhibit agro-medicinal properties conferring insecticidal as well as immunomodulatory and anti-cancer properties. The most prominent constituent of neem is azadirachtin, which has been established as a pivotal insecticidal ingredient. It acts as an antifeedant, repellent, and repugnant agent and induces sterility in insects by preventing oviposition and interrupting sperm production in males. This review discusses, key neem pesticidal components, their active functional ingredients along with recent strategies on employing nanocarriers, to provide controlled release of the active ingredients and to improve their stability and sustainability.

Transcriptomic changes underlie altered egg protein production and reduced fecundity in an estuarine model fish exposed to bifenthrin

Pyrethroid pesticides are a class of insecticides found to have endocrine disrupting properties in vertebrates such as fishes and in human cell lines. Endocrine disrupting chemicals (EDCs) are environmental contaminants that mimic or alter the process of hormone signaling. In particular, EDCs that alter estrogen and androgen signaling pathways are of major concern for fishes because these EDCs may alter reproductive physiology, behavior, and ultimately sex ratio. Bifenthrin, a pyrethroid with escalating usage, is confirmed to disrupt estrogen signaling in several species of fish, including Menidia beryllina (inland silverside), an Atherinid recently established as a euryhaline model. Our main objective was to broadly assess the molecular and physiological responses of M. beryllina to the ng/L concentrations of bifenthrin typically found in the environment, with a focus on endocrine-related effects, and to discern links between different tiers of the biological hierarchy. As such, we evaluated the response of juvenile Menidia to bifenthrin using a Menidia-specific microarray, quantitative real-time polymerase chain reaction (qPCR) on specific endocrine-related genes of interest, and a Menidia-specific ELISA to the egg-coat protein choriogenin, to evaluate a multitude of molecular-level responses that would inform mechanisms of toxicity and any underlying causes of change at higher biological levels of organization. The sublethal nominal concentrations tested (0.5, 5 and 50ng/L) were chosen to represent the range of concentrations observed in the environment and to provide coverage of a variety of potential responses. We then employed a 21-day reproductive assay to evaluate reproductive responses to bifenthrin (at 0.5ng/L) in a separate group of adult M. beryllina. The microarray analysis indicated that bifenthrin influences a diverse suite of molecular pathways, from baseline metabolic processes to carcinogenesis. A more targeted examination of gene expression via qPCR demonstrated that bifenthrin downregulates a number of estrogen-related transcripts, particularly at the lowest exposure level. Choriogenin protein also decreased with exposure to increasing concentrations of bifenthrin, and adult M. beryllina exposed to 0.5ng/L had significantly reduced reproductive output (fertilized eggs per female). This reduction in fecundity is consistent with observed changes in endocrine-related gene expression and choriogenin production. Taken together, our results demonstrate that environmental concentrations of bifenthrin have potential to interfere with metabolic processes, endocrine signaling, and to decrease reproductive output.

Disruptive environmental chemicals and cellular mechanisms that confer resistance to cell death

Cell death is a process of dying within biological cells that are ceasing to function. This process is essential in regulating organism development, tissue homeostasis, and to eliminate cells in the body that are irreparably damaged. In general, dysfunction in normal cellular death is tightly linked to cancer progression. Specifically, the up-regulation of pro-survival factors, including oncogenic factors and antiapoptotic signaling pathways, and the down-regulation of pro-apoptotic factors, including tumor suppressive factors, confers resistance to cell death in tumor cells, which supports the emergence of a fully immortalized cellular phenotype. This review considers the potential relevance of ubiquitous environmental chemical exposures that have been shown to disrupt key pathways and mechanisms associated with this sort of dysfunction. Specifically, bisphenol A, chlorothalonil, dibutyl phthalate, dichlorvos, lindane, linuron, methoxychlor and oxyfluorfen are discussed as prototypical chemical disruptors; as their effects relate to resistance to cell death, as constituents within environmental mixtures and as potential contributors to environmental carcinogenesis.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: focus on the cancer hallmark of tumor angiogenesis

One of the important 'hallmarks' of cancer is angiogenesis, which is the process of formation of new blood vessels that are necessary for tumor expansion, invasion and metastasis. Under normal physiological conditions, angiogenesis is well balanced and controlled by endogenous proangiogenic factors and antiangiogenic factors. However, factors produced by cancer cells, cancer stem cells and other cell types in the tumor stroma can disrupt the balance so that the tumor microenvironment favors tumor angiogenesis. These factors include vascular endothelial growth factor, endothelial tissue factor and other membrane bound receptors that mediate multiple intracellular signaling pathways that contribute to tumor angiogenesis. Though environmental exposures to certain chemicals have been found to initiate and promote tumor development, the role of these exposures (particularly to low doses of multiple substances), is largely unknown in relation to tumor angiogenesis. This review summarizes the evidence of the role of environmental chemical bioactivity and exposure in tumor angiogenesis and carcinogenesis. We identify a number of ubiquitous (prototypical) chemicals with disruptive potential that may warrant further investigation given their selectivity for high-throughput screening assay targets associated with proangiogenic pathways. We also consider the cross-hallmark relationships of a number of important angiogenic pathway targets with other cancer hallmarks and we make recommendations for future research. Understanding of the role of low-dose exposure of chemicals with disruptive potential could help us refine our approach to cancer risk assessment, and may ultimately aid in preventing cancer by reducing or eliminating exposures to synergistic mixtures of chemicals with carcinogenic potential.

The organochlorine p,p'-dichlorodiphenyltrichloroethane induces colorectal cancer growth through Wnt/β-catenin signaling

Dichlorodiphenyltrichloroethane (DDT), an organochlorine pollutant, is associated with several types of cancer. However, the relationship between DDT and colorectal cancer is uncertain. In this study, the impact of p,p'-DDT on colorectal cancer growth was evaluated using both in vitro and in vivo models. Our results indicated that the proliferation of human colorectal adenocarcinoma DLD1 cells was significantly promoted after exposed to low concentrations of p,p'-DDT ranging from 10(-12) to 10(-7) M for 96 h. Exposure to p,p'-DDT from 10(-10) to 10(-8) M led to upregulation of phospho-GSK3β (Ser9), β-catenin, c-Myc and cyclin D1 in DLD1 cells. RNA interference of β-catenin inhibited the proliferation of DLD1 cells stimulated by p,p'-DDT. Inhibiting of estrogen receptors (ERs) had no significant effect on the action of p,p'-DDT. Treatment with p,p'-DDT induced production of intracellular reactive oxygen species (ROS) and inhibited superoxide dismutase (SOD) activity in DLD1 cells. Treatment with N-acetyl-L-cysteine (NAC), a ROS inhibitor, suppressed the induction of Wnt/β-catenin signaling and DLD1 cell proliferation by p,p'-DDT. Moreover, in a mouse xenograft model, 5 nmol/kg p,p'-DDT resulted in increased tumor size, oxidative stress and Wnt/β-catenin signaling. These results indicated that low concentrations of p,p'-DDT promoted colorectal cancer growth through Wnt/β-catenin signaling, which was mediated by oxidative stress. The finding suggests an association between low concentrations of p,p'-DDT exposure and colorectal cancer progression.

Environmental toxins

This review comprehensively summarizes the effects of more than 15 mostly used pesticides on male reproductive physiology, as recent experimental and epidemiological research have indicated their alarming impact on overall human health. Mechanisms have described that pesticide exposure damages spermatozoa, alter Sertoli or Leydig cell function, both in vitro and in vivo and thus affects semen quality. But, the literature suggests a need for more intricate research in those pesticides that are defined as mutagens or carcinogens and directly affect the hypothalamic–pituitary–gonadal axis. This literature review also proposes specific solutions to overcome these health effects.

Enantioselective effects of alpha-hexachlorocyclohexane (HCH) isomers on androgen receptor activity in vitro

Alpha-hexachlorocyclohexane (alpha-HCH), a part of the HCH pesticide mixture, is one of the most widespread persistent organic pollutants. Interestingly, only limited number of studies addressed the toxicity of alpha-HCH and the effects of its individual optical isomers have not been investigated in detail. In the present study we separated two alpha-HCH enantiomers by preparative HPLC and studied their activities towards androgen receptor (AR) using the MDA-kb2 cell line stably transfected with the luciferase reporter gene under the control of AR. There was no direct effect of alpha-HCH on AR but both isomers significantly suppressed the activity of AR in co-exposure with the natural ligand dihydrotestosterone in a concentration-dependent manner. One of the enantiomers appeared to be more active at lower concentration, which was also supported by the molecular modeling calculations with AR that showed a slight difference in estimated free energy of binding and inhibition constant between two enantiomers. Although studies with other pesticides demonstrated strong enantioselective differences in toxicity, the present research shows rather minor differences in modulations of AR by both alpha-HCH enantiomers. For the first time, enantioselective effects of alpha-HCH were demonstrated and the results suggest interaction with multiple regulatory events controlling the AR activity. Full elucidation of the toxicity mechanism will require further research.

Effect of endocrine disruptor pesticides: a review

Endocrine disrupting chemicals (EDC) are compounds that alter the normal functioning of the endocrine system of both wildlife and humans. A huge number of chemicals have been identified as endocrine disruptors, among them several pesticides. Pesticides are used to kill unwanted organisms in crops, public areas, homes and gardens, and parasites in medicine. Human are exposed to pesticides due to their occupations or through dietary and environmental exposure (water, soil, air). For several years, there have been enquiries about the impact of environmental factors on the occurrence of human pathologies. This paper reviews the current knowledge of the potential impacts of endocrine disruptor pesticides on human health.

Prostate cancer and ambient pesticide exposure in agriculturally intensive areas in California

In a population-based case-control study in California's intensely agricultural Central Valley (2005-2006), the authors investigated relations between environmental pesticide/fungicide exposure and prostate cancer. Cases (n = 173) were obtained from a population-based cancer registry, and controls (n = 162) were obtained from Medicare listings and tax assessor mailings. Past ambient exposures to pesticides/fungicides were derived from residential history and independently recorded pesticide and land-use data, using a novel geographic information systems approach. In comparison with unexposed persons, increased risks of prostate cancer were observed among persons exposed to compounds which may have prostate-specific biologic effects (methyl bromide (odds ratio = 1.62, 95% confidence interval: 1.02, 2.59) and a group of organochlorines (odds ratio = 1.64, 95% confidence interval: 1.02, 2.63)) but not among those exposed to other compounds that were included as controls (simazine, maneb, and paraquat dichloride). The authors assessed the possibility of selection bias due to less-than-100% enrollment of eligible cases and controls (a critical methodological concern in studies of this kind) and determined that there was little evidence of bias affecting the estimated effect size. This study provides evidence of an association between prostate cancer and ambient pesticide exposures in and around homes in intensely agricultural areas. The associations appear specific to compounds with a plausible biologic role in prostate carcinogenesis.

Prostate cancer risk and exposure to pesticides in British Columbia farmers

BACKGROUND

Several epidemiologic studies have reported an increased risk of prostate cancer among farmers. Our aim was to assess the risk of developing prostate cancer in relation to exposure to specific active compounds in pesticides.

METHOD

A case-control approach was used with 1,516 prostate cancer patients and 4,994 age-matched internal controls consisting of all other cancer sites excluding lung cancer and cancers of unknown primary site. Lifetime occupational history was obtained through a self-administered questionnaire and used in conjunction with a job exposure matrix to estimate the participants' lifetime cumulative exposure to approximately 180 active compounds in pesticides. Conditional logistic regression was used to assess prostate cancer risk, adjusting for potential confounding variables and effect modifiers. These include age, ethnicity, alcohol consumption, smoking, education, and proxy respondent.

RESULTS AND CONCLUSIONS

The significant association between prostate cancer risk and exposure to DDT (OR = 1.68; 95% CI: 1.04-2.70 for high exposure), simazine (OR = 1.89; 95% CI: 1.08-3.33 for high exposure), and lindane (OR = 2.02; 95% CI: 1.15-3.55 for high exposure) is in keeping with those previously reported in the literature. We also observed a significant excess risk for several active ingredients that have not been previously reported in the literature such as dichlone, dinoseb amine, malathion, endosulfan, 2,4-D, 2,4-DB, and carbaryl. Some findings in our study were not consistent with those reported in the literature, including captan, dicamba, and diazinon. It is possible that these findings showed a real association and the inconsistencies reflected differences of characteristics between study populations.

Plasma organochlorine levels and prostate cancer risk

A case-control study was conducted to determine the association between plasma organochlorine levels and prostate cancer risk. Male clinic patients scheduled for prostate core biopsy or seeing their urologist for other conditions from 1997 through 1999 in Kingston, Ontario were eligible, excluding those with an earlier cancer. Age frequency matched controls (n=329) were compared with 79 incident prostate cancer cases. Before knowledge of diagnosis, the patients completed a questionnaire and donated 15 ml of blood for the measurement of 14 PCBs, and 13 organochlorine pesticides by gas chromatography. At least 70% of patients had detectable levels of nine PCB congeners and seven pesticides, and these chemicals were included in the risk analysis adjusted for total lipids. Geometric means for these PCB congeners, total PCBs, and p,p'-DDE are slightly lower for cases than controls, whereas the levels of p,p'-DDT and other pesticides are virtually equal. Adjusting for age and other confounders in multivariable logistic regression, odds ratios (ORs) are consistently below 1.0 for PCB congeners and total PCBs. For pesticides, most ORs are very close to the null. This study suggests that long-term low-level exposure to organochlorine pesticides and PCBs in the general population does not contribute to increased prostate cancer risk.

Plasma organochlorines and subsequent risk of prostate cancer in Japanese men: a nested case-control study

BACKGROUND

Although accumulating evidence suggests that exposure to organochlorine pesticides and polychlorinated biphenyls (PCBs) may contribute to the development of prostate cancer, few investigations have used biological samples to classify exposure to specific organochlorines. To our knowledge, this is the first prospective study to investigate the association between blood levels of organochlorines and prostate cancer risk.

METHODS

We conducted a nested case-control study using data from the Japan Public Health Center-based Prospective (JPHC) Study. A total of 14,203 men 40-69 years old who returned the baseline questionnaire and who provided blood samples were followed from 1990 to 2005. Using a mean follow-up period of 12.8 years, we identified 201 participants who were newly diagnosed with prostate cancer. Two matched controls for each case were selected from the cohort. We used a conditional logistic regression model to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for prostate cancer in relation to plasma levels of nine organochlorines: PCBs, dichlorodiphenyltrichloroethane (DDT), hexachlorobenzene (HCB), beta-hexachlorocyclohexane (beta-HCH), trans- and cis-nonachlor, oxychlordane, and mirex.

RESULTS

No statistically significant association with total prostate cancer was seen for any plasma organochlorine, although we did observe an insignificant inverse association for plasma HCB and beta-HCH. Total PCB in plasma was also inversely associated with advanced prostate cancer but without statistical significance.

CONCLUSION

Our results suggest that no overall association exists between prostate cancer and organochlorines at the levels measured in our study population.

2,2-bis(4-chlorophenyl)-1,1-dichloroethylene stimulates androgen independence in prostate cancer cells through combinatorial activation of mutant androgen receptor and mitogen-activated protein kinase pathways

Therapy resistance represents a major clinical challenge in disseminated prostate cancer for which only palliative treatment is available. One phenotype of therapy-resistant tumors is the expression of somatic, gain-of-function mutations of the androgen receptor (AR). Such mutant receptors can use noncanonical endogenous ligands (e.g., estrogen) as agonists, thereby promoting recurrent tumor formation. Additionally, selected AR mutants are sensitized to the estrogenic endocrine-disrupting compound (EDC) bisphenol A, present in the environment. Herein, screening of additional EDCs revealed that multiple tumor-derived AR mutants (including T877A, H874Y, L701H, and V715M) are sensitized to activation by the pesticide 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (DDE), thus indicating that this agent may impinge on AR signaling in cancer cells. Further investigation showed that DDE induced mutant AR recruitment to the prostate-specific antigen regulatory region, concomitant with an enhancement of target gene expression, and androgen-independent proliferation. By contrast, neither AR activation nor altered cellular proliferation was observed in cells expressing wild-type AR. Activation of signal transduction pathways was also observed based on rapid phosphorylation of mitogen-activated protein kinase (MAPK) and vasodilator-stimulated phosphoprotein, although only MAPK activation was associated with DDE-induced cellular proliferation. Functional analyses showed that both mutant AR and MAPK pathways contribute to the proliferative action of DDE, as evidenced through selective abrogation of each pathway. Together, these data show that exposure to environmentally relevant doses of EDCs can promote androgen-independent cellular proliferation in tumor cells expressing mutant AR and that DDE uses both mutant AR and MAPK pathways to exert its mitogenic activity.

Endocrine disrupting pesticides: implications for risk assessment

Endocrine disrupting (ED) chemicals are compounds that alter the normal functioning of the endocrine system, potentially causing disease or deformity in organisms and their offspring. Pesticides are used widely to kill unwanted organisms in crops, public areas, homes and gardens and medicinally to kill parasites. Many are proven or suspected to be EDs. Ancient physiological similarities between different vertebrate groups suggest that disorders observed in wildlife may indicate risks to humans. This makes accurate risk assessment and effective legislation difficult. In this paper, the hazardous properties of pesticides which are known to have ED properties are reviewed in order to assess the implications for risk assessment. As well as data on sources of exposure in the United Kingdom (UK) an assessment of the evidence on the health effects of ED pesticides is also included. In total, 127 have been identified from the literature and their effects and modes of action are listed in this paper. Using the UK as a case study, the types and quantities of pesticides used, and their methods of application are assessed, along with their potential pathways to humans. In the UK reliable data are available only for agricultural use, so non-agricultural routes of pesticide exposure have been poorly quantified. The exposure of people resident in or visiting rural areas could also have been grossly under-estimated. Material links between ED pesticide use and specific illnesses or deformities are complicated by the multifactorial nature of disease, which can be affected by factors such as diet. Despite these difficulties, a large body of evidence has accumulated linking specific conditions to ED pesticides in wildlife and humans. A more precautionary approach to the use of ED pesticides, especially for non-essential purposes is proposed.

Prostate cancer prevention: past, present, and future

Prostate cancer is the most common male malignancy and the second or third leading cause of cancer death among men in the West. The descriptive epidemiology of prostate cancer suggests that it is a preventable disease. Prevention has the theoretical advantage of not only saving lives, but also reduce the morbidity of radical prostate cancer therapy. This article reviews the past, present, and future of prostate cancer prevention. In particular, the evidence and scientific data of a variety of prevention strategies are reviewed. Strategies reviewed include dietary fat reduction and supplementation with vitamins D and E, and selenium. Dietary intake of soy, green tea, and tomato-rich products (lycopene) are also reviewed. Data regarding pharmacological intervention with cyclo-oxygenease inhibitors, antiestrogens, and in particular 5-alpha reductase inhibitors are reviewed. The results of the Prostate Cancer Prevention Trial including the controversy surrounding higher-grade cancers among men randomized to finasteride are also summarized. Finally, a variety of trial designs as well as a roster of current phase 2 trials are presented. Probably no cancer is being investigated more thoroughly in the context of prevention as prostate cancer in 2007. Definitive answers to pivotal phase 3 trials will be available in the coming 2 to 7 years.

Comparison of prostate cancer cell lines for androgen receptor-mediated reporter gene assays

In order to select a better prostate cancer cell model for androgen receptor (AR)-mediated reporter gene assays, we assessed the androgen response characteristics of three cell lines, LNCaP, PC3/AR(+) and 22Rv1, in this study. Both the mRNA and the proteins of AR and glucocorticoid receptor (GR) were expressed in all three cell lines. Among the three cell lines, only in LNCaP cells, DHT concentration-dependently stimulated proliferation. DHT induced the luciferase activity in three cell lines which were transiently transfected with pMMTV-Luc, in a concentration-dependent manner. The maximum induction was 24.0-fold and 13.4-fold in 22Rv1 and in the LNCaP respectively. PC3/AR(+) were more sensitive to respond to DHT at a minimal concentration of 10(-12)M by 14.0-fold induction. The transcriptional activity induced with 10(-8)M DHT was inhibited about 50-75% in the PC3/AR(+) and 22Rv1, and 98% in the LNCaP, by vinclozolin. Dexamethasone concentration-dependently induced the luciferase activity in PC3 and 22Rv1, but not in the LNCaP. However, the response to dexamethasone in 22Rv1 was very weak compared to DHT. The (anti)androgencity of seven pyrethroids was assessed via an AR-mediated luciferase reporter assay. None of them showed the androgenic action in all three cell lines. Permethrin inhibited the DHT induced luciferase activity about 22%, 35.8% and 75.5% in 22Rv1, PC3/AR(+) and LNCaP, respectively. Based on results from in this study and cell line character, 22Rv1 cells seemed to be an appropriate model for the screening of androgenic endocrine disruptors, although it needs further studies with other steroid receptor and thyroid receptor.

Serum free BG-1 cell proliferation assay: A sensitive method for determining organochlorine pesticide estrogen receptor activation at the nanomolar range

Most xenobiotic estrogeniety assay methods rely on direct agonist action on the estrogen receptor (ER) to approximate activation potential. Such methods do have drawbacks since some ER activating pesticides are weak or non-agonistic in ligand-binding assays. This study discusses a method that detects pesticide estrogenic actions regardless of ER ligand binding ability. Using a serum-free BG-1 ovarian cell culture model, we investigated the ability of several organochlorine (OC) pesticides to stimulate known estrogenic actions. We observed concentration dependent ER mediated cell proliferation in BG-1 cells using heptachlor epoxide (HE), beta-hexachlorohexane (beta-HCH), and endosulfan (Endo). In addition, we observed upregulation of the ERE-dependent proteins progesterone receptor and PS2. Gel-shift/EMSA studies for ERE binding further supported these OC's ERE activating abilities. All of these effects were abolished using ICI 164,384(ICI). Using the same culture conditions, we tested the blocking action of growth factor antibodies for erbB2(9G6) and insulin-like growth factor (IGF-Ab) receptors and discovered they inhibited BG-1 proliferation (9G6: HE and beta-HCH/ IGF-Ab: Endo.) This experiment confirms the existence of a possible cross-talk between ER and growth factor receptors in OC ligand-dependent activation and also validates this sensitive method for determining both ligand-dependent and independent estrogenic activity of selected pesticides.

Prostate cancer in US Air Force veterans of the Vietnam war

US Air Force veterans of Operation Ranch Hand sprayed herbicides contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in Vietnam from 1962 to 1971. Comparisons served in Southeast Asia (SEA) during the same time period but did not spray herbicides. Here we investigate a potential association between exposure to TCDD and prostate cancer. Data were available for 2516 veterans (1019 Ranch Hand and 1497 Comparison) who participated in at least one of six physical examinations starting in 1982 and had a measurement of serum TCDD. We assigned Ranch Hands to two exposure categories: Lower and Higher, based on their median 20-year cumulative TCDD level. In total, 81 Comparison and 59 Ranch Hand prostate cancers were identified between 1 January 1982 and 31 December 2003. We found no overall increase in the risk of prostate cancer in Ranch Hand veterans versus the Comparisons. There was a positive association in Ranch Hand veterans in the Higher TCDD category who served in SEA before 1969 (RR=2.27, 95% CI 1.11-4.66) when more contaminated herbicides were used, but the number of cases was small (n=15). A within-group comparison found that in Comparison veterans, time served in SEA was associated with an increased risk of prostate cancer (RR=2.18, 95% CI 1.27-3.76, >789 days versus < or =789 days). No increase in the risk of prostate cancer was observed within the Ranch Hand group in association with TCDD or time served in SEA. These analyses suggest that a longer service in SEA and exposures other than TCDD may have increased the risk of prostate cancer in Comparison veterans.

HER-2/neu and CD117 (c-kit) overexpression in patients with pesticide exposure and extensive stage small cell lung carcinoma (ESSCLC)

BACKGROUND

The rate of detection of HER-2/neu and CD117 (c-kit) overexpression in small cell lung cancer (SCLC) has varied widely; between 5-35% and 21-70% respectively.

METHODS

To evaluate the relationship between pesticide exposure and HER-2/neu and CD117 overexpression in extensive stage SCLC (ESSCLC), we identified patients with ESSCLC and assessed pesticide exposure using a predetermined questionnaire. An exposure index (hours/day x days/year x years) > or = 2400 hours was considered as 'exposed.' HER-2/neu overexpression was evaluated on archival tissue using the DAKO Hercep test, and CD117 testing was performed using immunohistochemistry (A4052 polyclonal antibody).

RESULTS

193 ESSCLC patients were identified. Pesticide exposure data could be obtained on 174 patients (84 females and 109 males) with a mean age of 68.5 years. 53/174 (30.4%) revealed HER-2/neu overexpression. 54/174 (31.03%) specimens showed CD117 overexpression by IHC. On multivariate analysis, HER-2/neu overexpression was associated with diminished survival (p < 0.001). In comparison, CD117 expression did not have an adverse prognostic value (p = 0.025). 41/53 (77.4%) patients with HER-2/neu overexpression and 47/121 (38.8%) patients without overexpression had exposure to pesticides (odds ratio: 5.38; p < 0.01). Among the cohort tested for CD117, 29/54 (53.7%) patients with CD117 overexpression and 59/120 (49.2%) patients without CD117 overexpression had pesticide exposure (odds ratio: 1.18; p = 0.12).

CONCLUSION

Pesticide exposure affects HER-2/neu but not CD117 overexpression. Future studies are needed to determine specific pesticide(s)/pesticide components that are responsible for HER-2/neu overexpression in ESSCLC, and to validate our findings in other solid tumors that overexpress HER-2/neu.

Xenobiotic-induced TNF-alpha expression and apoptosis through the p38 MAPK signaling pathway

Some xenobiotics, such as dichlorodiphenyltrichloroethane (DDT), bind to and activate estrogen receptors (ERs), eliciting estrogenic effects in both wildlife and humans. However, our laboratory and others have demonstrated that DDT and DDT-like compounds target non-ER pathways. In search for a molecular mechanism we recently established that DDT and its metabolites stimulate activator protein-1 (AP-1)-mediated gene expression through the p38 mitogen-activated protein kinase (MAPK) cascade. Here, we determined that DDT-induced p38 activity produces a novel environmental signaling pathway in endometrial Ishikawa and human embryonic kidney (HEK) 293 cells. Xenobiotic exposure stimulates expression of the death ligand, tumor necrosis factor-alpha (TNF-alpha) as demonstrated using RT-PCR and reporter gene assays. Furthermore, DDT-induced p38 activity led to the release of cytochrome c from the mitochondria and activation of caspase-3/7. Ultimately, DDT-treated cells underwent cell death. Taken together, these data demonstrate DDT induces both the expression of the death ligand TNF-alpha and apoptosis through a p38 MAPK-dependent mechanism.

Exposure to pesticides increases levels of uPA and uPAR in pre-malignant human prostate cells

Pesticides are associated with prostate carcinogenesis and mortality; however, their exact mechanisms of action are poorly defined. We have used a transformed but non-tumorigenic human prostate epithelial line to determine the effect of common herbicides and insecticides on expression of urokinase and its receptor, uPAR. The herbicide Roundup and insecticides Lorsban and Warrior induced uPA while Lorsban and Warrior also induced uPAR. Furthermore, a combination of Roundup + Lorsban or Roundup + Warrior produced greater increases in uPA and uPAR than when agents were used alone. Both active and "inactive" chemicals within these pesticides are important for the effects observed as the neat chemicals alone failed to induce uPA and were less potent inducers of uPAR. Thus, specific pesticide formulations, especially when combined, can increase uPA and uPAR expression in vitro in transformed prostate epithelial cells.

Prostate cancer among pesticide applicators: a meta-analysis

OBJECTIVES

To analyse data from peer-reviewed, case-referent and cohort studies, studying the occurrence of prostate cancer in pesticide applicators and in some other, related, occupational categories, in order to determine a possible relationship of cancer of the prostate with pesticide exposure; to calculate a meta-rate ratio and to compare it with the meta-rate ratios obtained in a previous meta-analysis performed over a shorter time (1995-2001) in a broader exposure category, including many pesticide-related agricultural and non-agricultural occupations.

METHODS

Medline was searched for the years between 1966 and 2003, and relevant studies were identified from 1986 on. We conducted a meta-analysis of 22 studies complying with the inclusion criteria in order to pool their relative risk (RR) estimates. Studies were summarised and assessed for homogeneity and publication bias.

RESULTS

The meta-rate ratio, based on 22 estimates of RR, is 1.24 [95% confidence interval (95% CI) 1.06-1.45]. This pooled risk estimate for the occupational categories selected is higher than the one previously calculated for farmers in general over a shorter period of publication. Substantial heterogeneity of rate ratios exists between the different studies. The major source of heterogeneity identified is geographic location. Increased meta-rate ratios are observed for studies derived from North America as well as from Europe, the meta-rate ratios from Europe being lower than those from North America. There is no obvious indication of publication bias.

CONCLUSION

The increased meta-rate ratio for prostate cancer in agricultural pesticide applications provides additional evidence for a possible relationship between pesticide exposure and prostate cancer. The homogeneity observed between the individual rate ratios, after we had regrouped the data according to geographic location, tends to increase the consistency of the association. However, the data available from the individual studies do not provide sufficient exposure information for firm conclusions to be drawn about pesticide exposure as the cause of prostate cancer, independently from other factors.

Mitogen Activated Protein kinase signal transduction pathways in the prostate

The biochemistry of the mitogen activated protein kinases ERK, JNK, and p38 have been studied in prostate physiology in an attempt to elucidate novel mechanisms and pathways for the treatment of prostatic disease. We reviewed articles examining mitogen-activated protein kinases using prostate tissue or cell lines. As with other tissue types, these signaling modules are links/transmitters for important pathways in prostate cells that can result in cellular survival or apoptosis. While the activation of the ERK pathway appears to primarily result in survival, the roles of JNK and p38 are less clear. Manipulation of these pathways could have important implications for the treatment of prostate cancer and benign prostatic hypertrophy.

Dietary Fat and Prostate Cancer

PURPOSE

Data from histopathological and migratory studies suggest that 1 or more late stage environmental promoters are involved in the development of clinical carcinoma of the prostate. Laboratory investigations and variously designed epidemiological studies in man have suggested that dietary fat may be one of these candidate tumor promoters but other studies have questioned this association. The biologically plausible associations that have been hypothesized include total energy consumption, altered androgen metabolism, oxidative stress, specific fatty acid consumption and pesticide intake. We provide a critical appraisal of the existing evidence for an association between dietary fat consumption and prostate cancer, and review the biologically plausible relationships.

MATERIALS AND METHODS

All 33 published case-control and cohort studies that examined the relationship between prostate cancer and dietary fat or specific fatty food types were critically appraised. Eight studies suggested a statistically significant association, and many studies noted significant associations for specific types of fatty foods (eg milk or meat) and prostate cancer.

RESULTS

In light of the inherent biases in the methodology of studying dietary fat intake and carcinoma of the prostate, we conclude that the evidence is consistent.

CONCLUSIONS

Corroborative studies in humans are required to better define this relationship. Prospective studies of dietary intervention should be encouraged.

Prevalence of pesticide exposure in young males (</= 50 years) with adenocarcinoma of the prostate

Evidence implicating pesticides as causative agents of prostate cancer is controversial, and specifically, data in young adults is lacking. Hence, we performed a preliminary study evaluating the relationship between pesticide exposure and prostate cancer in young males. After approval from the University of North Dakota Institutional Review Board and Human Subjects Committee, a retrospective study was performed on all young males (</ = 50 years) with a biopsy-proven diagnosis of carcinoma of the prostate. The records of all patients aged less than/equal to 50 years, with a diagnosis of adenocarcinoma of the prostate, from January 1991 through December 2001 were reviewed. Pesticide risk assessment interviews were performed by a single member of the team, for consistency, via telephone on the basis of a pre-determined questionnaire investigating occupations and hobbies with special emphasis on: Duration of exposure. An exposure index was calculated for each interviewed subject according to the following formula: hours/day x days/year x years. Patients with an exposure index >2400 hours were considered as 'exposed.' The 2400 hour cut-off value was chosen on the basis of previous reports indicating that this figure represents heavy exposure to genotoxic agents. Statistical analysis was obtained using SPSS-10ledR;. Between 1991 and 2001, 61 young males with adenocarcinoma of the prostate were identified, of whom 56 patients with a mean age of 47 years (range: 40-49) had complete records of treatment and could be contacted for completion of the questionnaire. The most common stage at presentation was Stage III and the mean Gleason's score was 7.5 (range 5-9). Interestingly, almost a third (16/56, 28.6%) of patients had stage IV disease at presentation. 37/56 (66.1%) patients had 'significant' exposure in our study. In addition, interestingly, the mean survival in the subgroup of patients with pesticide exposure was 11.3 months (SD: +/- 2.3 months), while the mean survival in the patients without pesticide exposure (n = 19) was 20.1 months (SD: +/- 3.1 months), with p-value <0.01. Although our study is relatively small, it does reveal preliminary evidence linking pesticide exposure to the early development of, possibly aggressive, prostate adenocarcinoma. Future, larger, epidemiological studies are needed to confirm the findings of our study.

Prostate cancer and exposure to pesticides in agricultural settings

Our study evaluates the association between prostate cancer and exposure to pesticides in agricultural settings in Italy. The data were derived from a hospital-based multi-site case-control study carried out in 5 rural areas between 1990-92. In our study, 124 new cases of prostate cancer were ascertained and interviewed, along with 659 cancer controls. A team of agronomists assessed past exposure to pesticides by using a checklist of 100 chemical families and 217 compounds applied from 1950-85 in the areas considered. The association between prostate cancer and different occupational risk factors was measured by maximum likelihood estimation of the odds ratio, controlling for potential confounders. "Ever been employed in agriculture" was associated with a 40% increased risk (OR = 1.4, 95% CI = 0.9-2.0). Prostate cancer was also related positively to food and tobacco (OR= 2.1, 95% CI = 1.1-4.1), and chemical products (OR = 2.2, 95% CI = 0.7-7.2) industries. The analyses carried out to estimate the association between different types of pesticides and prostate cancer showed increased risks among farmers exposed to organochlorine insecticides and acaricides (OR = 2.5, 95% CI = 1.4-4.2), more specifically to the often contemporary used compounds DDT (OR = 2.1, 95% CI = 1.2-3.8), and dicofol (OR = 2.8, 95% CI = 1.5-5.0), whose effects could not be well separated.