Phthalates and polycystic ovary syndrome - Systematic literature review.

Polycystic ovary syndrome (PCOS), one of the most common endocrine disorders in women, may involve both environmental and genetic factors. One potential environmental factor of concern is exposure to phthalates and other endocrine disrupting chemicals many of which have adverse effects on the female reproductive system. The aim of this systematic review was to evaluate possible association between prenatal phthalate exposure and PCOS. Six databases were searched for relevant human studies. Inclusion criteria were female human population diagnosed with PCOS and exposed during any lifestage to any phthalate or phthalate metabolite through oral, dermal, inhalation, or intravenous route. Search results were screened for relevance, and studies that met the inclusion criteria were evaluated for study quality using Joanna Briggs Institute (JBI) critical appraisal tools. The systematic literature search yielded seven articles, six case-control studies and one cohort study. Three studies found a significant positive association, two studies found a significant negative association, and two studies found no association between phthalate exposure and the incidence of PCOS. Even though studies found no consistent pattern on association with phthalates and PCOS, the results of analyzed studies did not exclude possible effects of phthalates on the female reproductive and metabolic system. Some of the factors in study design such as recruiting participants from IVF clinics and young age of participants may have biased the results. Further studies with more careful study design and longer follow-up time are needed to bring more reliable information about the role of phthalates in onset of PCOS.

Leaching of metals from red mud and toxicity in human cells in vitro.

Toxicity of red mud, a waste from alumina production, was studied using human breast cancer MCF-7 cells. Culture medium was prepared by mixing water for 3 days with the red mud and removing solid particles afterwards (red mud water). Culture for 48 h of the cells in this medium in neutral pH decreased the cell viability, as analyzed by the MTT-test, and increased the formation of reactive oxygen species. Thus, neutralization does not eliminate the toxicity of red mud. In preliminary experiments, a combined effect of five metals (Cr, Li, V, Al, As) increased the formation of ROS (reactive oxygen species) statistically significantly. Each element separately did not have a similar effect. In environmental applications, red mud is likely to be used after activation. In this work, the red mud was activated using hydrochloric acid to study the physical and chemical properties before and after the treatment. Activation increased the specific surface area of red mud from 16 m2 g-1 to 148 m2 g-1, which is beneficial in many environmental applications such as in the adsorptive removal of pollutants. After activation, leaching of some elements from the red mud decreased (e.g. Al from 38.0 to 0.56 mg L-1, As from 21.0 to 2.1 µg L-1, V from 172.0 to 29.8 µg L-1) while some increased (e.g. Li from 0.04 to 2.81 mg L-1, Cr from 0.35 to 3.23 mg L-1).

Micro-sized polyethylene particles affect cell viability and oxidative stress responses in human colorectal adenocarcinoma Caco-2 and HT-29 cells.

Plastic is a widely utilized material and polyethylene is one of the most used plastic types. Microplastics are plastic particles (size <5 mm) which are primarily a micro-size range or results from degeneration of larger plastic pieces in the environment. Drinking water and food are two main human exposure sources for microplastics and consequently effects of microplastics in gastrointestinal tract are considered important. Still, only little is known how microplastics and plastic associated chemicals affect the human health. The aim of our study was to evaluate the ability of micro-sized polyethylene to cause harmful effects in human intestinal cells. Raw ultra-high molecular-weight polyethylene (size 5-60 µm) was used. In addition, polyethylene particles were extracted with ethanol to determine the effect of extraction process on toxicity of the particles. In the experiments, human colorectal adenocarcinoma Caco-2 and HT-29 cells were exposed to polyethylene (0.25-1.0 mg/ml) or extracts for 48 h. After exposure, cell viability and cytotoxicity were assessed with MTT and lactate dehydrogenase assay. Reactive oxygen species (ROS) production was measured with dichlorofluorescin diacetate and cytoplasmic production of superoxide with dihydroethidium and mitochondrial superoxide production with MitoSOX. The 48-h exposure to polyethylene decreased dose-dependently cell viability and increased oxidative stress, especially mitochondrial superoxide production, in both cell lines. Effects on ROS or cytosolic superoxide production were not observed. Also, exposure to extracts decreased cell viability and increased oxidative stress in cell cultures, but there were differences between cell lines. These effects were most probably caused by the remaining particles rather than the compounds released from the plastic during the extraction. In conclusion, our study shows that micro-sized polyethylene and ethanol-extracted polyethylene in high concentrations decreased cell viability and increased oxidative stress responses in intestinal cells. These results contribute to the existing evidence on potential adverse human health effects of microplastics.

Association between different diabetes medication classes and risk of Parkinson's disease in people with diabetes.

PURPOSE: Diabetes has been associated with increased risk of Parkinson's disease (PD). Diabetes medications have been suggested as a possible explanation, but findings have been inconsistent. More information on the role of exposure in different time windows is needed because PD has long onset. We assessed the association between use of different diabetes medication categories and risk of PD in different exposure periods. METHODS: A case-control study restricted to people with diabetes was performed as part of nationwide register-based Finnish study on PD (FINPARK). We included 2017 cases (diagnosed 1999-2015) with PD and 7934 controls without PD. Diabetes medication use was identified from Prescription Register (1995-2015) and categorized to insulins, biguanides, sulfonylureas, thiazolidinediones (TZDs), dipeptidyl peptidase 4 (DPP-4) inhibitors, glucagon-like peptide-1 (GLP-1) analogues and glinide. Exposure for each medication class was determined as none, at least 3 years before outcome and only within the three-year lag time before PD outcome. RESULTS: The use of insulins, biguanides, sulfonylureas, DPP-4 inhibitors, GLP-1 analogues or glinides was not associated with PD. Use of TZDs before lag time compared to non-use of TZDs (adjusted odds ratio (OR) 0.78; 95% Confidence interval (CI) 0.64-0.95) was associated with decreased risk of PD. CONCLUSIONS: Our nationwide case-control study of people with diabetes found no robust evidence on the association between specific diabetes medication classes and risk of PD. Consistent with earlier studies, TZD use was associated with slightly decreased risk of PD. The mechanism for this should be verified in further studies.

Screening of SIRT6 inhibitors and activators: A novel activator has an impact on breast cancer cells.

Sirtuin 6 (SIRT6), a member of sirtuin family (SIRT1-7), regulates a variety of cellular processes involved in aging, metabolism, and cancer. Dysregulation of SIRT6 is widely observed in different breast cancer subtypes; however, the role and function of SIRT6 in cancer development remain largely unexplored. The aim of this study was to identify novel compounds targeting SIRT6 which may provide a new approach in development of anti-cancer therapy for breast cancer. Virtual screening was utilized to discover potential compounds targeting SIRT6 for in vitro screening. In addition, novel 1,4-dihydropyridine derivatives were synthetized and further subjected for the screening. The impact of the compounds on the deacetylation activity of SIRT6 was determined with HPLC method. The anti-cancer activities were screened for a panel of breast cancer cells. A set of 1,4-dihydropyridine derivatives was identified as SIRT6 inhibitors. A SIRT6 activating compound, (2,4-dihydroxy-phenyl)-2-oxoethyl 2-(3-methyl-4-oxo-2-phenyl-4H-chromen-8-yl)acetate (later called as 4H-chromen), was discovered and it provided 30-40-fold maximal activation. 4H-chromen was proposed to bind similarly to quercetin and place to previously reported SIRT6 activator sites. 4H-chromen was investigated in various breast cancer cells, and it decreased cell proliferation in all cells as well as arrested cell cycle in triple negative cells. Overall, this study describes a highly potent SIRT6 activator and new inhibitors that represent a novel tool to study the mechanism of SIRT6 function.

Effects of galloflavin and ellagic acid on sirtuin 6 and its anti-tumorigenic activities.

Sirtuin 6 (SIRT6), a member of sirtuin family (SIRT1-7), regulates distinct cellular functions; genome stability, DNA repair, and inflammation related diseases. Recently, we demonstrated that anthocyanidins in berries induce the catalytic activity of SIRT6. In this study, we explored the effects of Galloflavin and Ellagic acid, the most common polyphenols in berries, on SIRT6. SIRT6 deacetylation was investigated using HPLC and immunoblotting assays. The expression levels of SIRT6, glycolytic proteins and cellular metabolism were studied on human colon adenocarcinoma cells (Caco2). Molecular docking studies were carried out to study possible interactions of the compounds with sirtuins. Ellagic acid increased the deacetylase activity of SIRT6 by up to 50-fold; it showed moderate inhibition of SIRT1-3. Galloflavin and Ellagic acid showed anti-proliferative effects on Caco2. The compounds also upregulated SIRT6 expression whereas key proteins in glycolysis were downregulated. Galloflavin decreased glucose transporter 1 (GLUT1) expression, and Ellagic acid affected the expression of protein dehydrogenase kinase 1 (PDK1). Interestingly, both compounds caused reduction in glucose uptake and lactate production. Both Galloflavin and Ellagic acid were able to form hydrogen bonds with Asp188 and Gly6 in SIRT6. In this study, we showed that Galloflavin and Ellagic acid increased SIRT6 activity and decreased the expression of SIRT6 associated proteins involved in cancer development. Taken together, Galloflavin and Ellagic acid targeting SIRT6 activity may provide a new insight in the development of anti-cancer therapy.

Toxicity of diuron metabolites in human cells.

Diuron, a highly used herbicide worldwide, is metabolized into several toxic metabolites. DCA (3,4-dichloroaniline), DCPU [3-(3, 4-dichlorophenyl)urea] and DCPMU [3-(3,4-dichlorophenyl)-1-methyl urea] reduced viability of human placental choriocarcinoma BeWo, human breast adenocarcinoma MCF-7 and human colon adenocarcinoma Caco-2 cells as judged by the MTT assay, where color formation is dependent on functional mitochondria in viable cells. Based on the IC50 values in BeWo cells the order of cytotoxicity was DCA > DCPU > diuron > DCPMU, and in Caco-2 cells DCPMU > DCPU > DCA, diuron. In MCF-7 cells, only DCPU had an IC50 within the range of the concentrations used. In the PI-digitonin viability assay, only the highest concentration (200 µM) of DCPU caused a statistically significant decrease in viability in any cell line. There was no correlation between cytotoxicity and ROS production. This indicates that diuron metabolites are toxic in cells of human origin with mitochondria as the target, but ROS not the likely mechanism.

Impact of structurally diverse BET inhibitors on SIRT1.

The epigenetic regulation of gene expression is controlled by various processes, of which one is histone acetylation. Many proteins control gene expression via histone acetylation. Those proteins include sirtuins (SIRTs) and bromodomain and extraterminal proteins (BETs), which are known to regulate same cellular processes and pathways. The aim of this study was to explore BET inhibitors' effects on SIRT1. Previously we showed that BET inhibitor (+)-JQ1 increases SIRT1 levels, but in the current study we used also other, structurally diverse BET inhibitors, I-BET151 and Pfi-1, and examined their effects on SIRT1 levels in two breast cancer cell lines. The results differed between the inhibitors and also between the cell lines. (+)-JQ1 had opposite effects on SIRT1 levels in the two cell lines, I-BET151 increased the levels in both cell lines, and Pfi-1 had no effect. In conclusion, the effect of structurally diverse BET inhibitors on SIRT1 levels is divergent, and the responses might also be cell type-dependent. These findings are important for all SIRT1 and BET inhibitor-related research, and they show that different BET inhibitors might have important individual effects.

Photocatalysis and catalytic wet air oxidation: Degradation and toxicity of bisphenol A containing wastewaters.

Bisphenol A (BPA) is a commonly used chemical in consumer products. It is an endocrine disrupter that has potentially significant negative effects on human health. The use and chemical stability of BPA have resulted in the appearance of the chemical in wastewaters. Since the current wastewater treatment technologies are not effective enough to remove BPA, new methods to degrade BPA are required. In this paper, we report the efforts made towards developing a bi-functional catalyst for consecutive catalytic wet air oxidation-photocatalytic water treatment. It was found that 2.5% Pt/Ti0.8Ce0.2O2 is a potential bi-functional catalyst for the consecutive treatment. Concentration and toxicity of BPA were successfully reduced by catalytic wet air oxidation. Although BPA was further reduced by photocatalysis, it was not reflected in further decrease of cell toxicity. Thus wet-air oxidation combined with photocatalysis is a promising approach for the reduction of BPA.

Transplacental transfer and metabolism of diuron in human placenta.

Diuron is a broad-spectrum phenylurea derived herbicide which is commonly used across the globe. Diuron is toxic to the reproductive system of animals and carcinogenic to rat urothelium, and recently found to be genotoxic in human cells. In in vivo, it is metabolized predominately into 3-(3,4-dichlorophenyl)-1-methyl urea (DCPMU) in humans and 3-(3, 4-dichlorophenyl)urea (DCPU) in animals. Information on diuron toxicokinetics and related toxicity in human placenta is absent. We have investigated the toxicokinetics of diuron in ex vivo human placental perfusion and in in vitro human placental microsomes and human trophoblastic cancer cells (BeWo). Diuron crossed human placenta readily in placental perfusion. Furthermore, diuron was metabolized into DCPMU in perfused placenta and in in vitro incubations using microsomes from placentas of smokers. In incubations with placental microsomes from non-smokers, and in BeWo cells, metabolism to DCPMU was detected but only with the highest used diuron concentration (100 µM). Diuron metabolism was inhibited upon addition of α-naphthoflavone, a CYP1A1 inhibitor, underscoring the role of CYP1A1 in the metabolism. In conclusion, it is evident that diuron crosses human placenta and diuron can be metabolized in the placenta to a toxic metabolite via CYP1A1. This implicates in vivo fetal exposure to diuron if pregnant women are exposed to diuron, which may result in fetotoxicity.

Natural polyphenols as sirtuin 6 modulators.

Flavonoids are polyphenolic secondary metabolites synthesized by plants and fungus with various pharmacological effects. Due to their plethora of biological activities, they have been studied extensively in drug development. They have been shown to modulate the activity of a NAD+-dependent histone deacetylase, SIRT6. Because SIRT6 has been implicated in longevity, metabolism, DNA-repair, and inflammatory response reduction, it is an interesting target in inflammatory and metabolic diseases as well as in cancer. Here we show, that flavonoids can alter SIRT6 activity in a structure dependent manner. Catechin derivatives with galloyl moiety displayed significant inhibition potency against SIRT6 at 10 µM concentration. The most potent SIRT6 activator, cyanidin, belonged to anthocyanidins, and produced a 55-fold increase in SIRT6 activity compared to the 3-10 fold increase for the others. Cyanidin also significantly increased SIRT6 expression in Caco-2 cells. Results from the docking studies indicated possible binding sites for the inhibitors and activators. Inhibitors likely bind in a manner that could disturb NAD+ binding. The putative activator binding site was found next to a loop near the acetylated peptide substrate binding site. In some cases, the activators changed the conformation of this loop suggesting that it may play a role in SIRT6 activation.

Toxicity of diuron in human cancer cells.

Diuron is a substituted phenylurea used as a herbicide to control broadleaf and grass weeds and as a biocidal antifouling agent. Diuron is carcinogenic in rat urinary bladder and toxic to the reproductive system of oysters, sea urchins and lizards. The few studies carried out in human cells do not include the genotoxicity of diuron. We have investigated the toxicity of diuron in human breast adenocarcinoma (MCF-7) and human placental choriocarcinoma (BeWo) cells. The production of reactive oxygen species (ROS) was statistically significantly increased in both cell lines but only at the highest 200 µM concentration. Diuron clearly reduced the viability of BeWo, but not MCF-7 cells. The relative cell number was decreased in both cell lines indicative of inhibition of cell proliferation. In the Comet assay, diuron increased DNA fragmentation in MCF-7 but not in BeWo cells. The expressions of p53 protein, a marker for cell stress, and p21 protein, a transcriptional target of p53, were increased, but only in MCF-7 cells. In conclusion, our results suggest that diuron is cytotoxic and potentially genotoxic in a tissue-specific manner and that ROS play a role in its toxicity. Thus, exposure to diuron may exert harmful effects on fetal development and damage human health.

Characterization of human breast cancer cell lines for the studies on p53 in chemical carcinogenesis.

To know whether the molecular responses to chemical carcinogens reflect only cell line specific molecular responses, or whether they can be regarded as characteristic of breast tissue, we have characterized four human breast cancer cell lines (MDA-MB-231, MDA-MB-468, T47-D, ZR-75-1). The activation of benzo(a)pyrene (BP), a model compound of polycyclic aromatic hydrocarbons, to its genotoxic BP-diolepoxide (BPDE) and p53 response and cell viability after BP exposure, and the p53 status in these cell lines were analyzed. Both TP53 (exons 5-8) mutations and total and phospho-p53 were analyzed. Three of the four cell lines clearly activated BP to BPDE-DNA adducts (MDA-MB-468, T47-D, ZR-75-1) and three had a mutation in the TP53 gene (MDA-MB-231, MDA-MB-468, T47-D). After BP-treatment the strongest p53 protein induction and phosphorylation at serine 392 was found in ZR-75-1 cells with a wt TP53 gene. Viability decreased dramatically only in ZR-75-1 and MDA-MB-468 cells although the relative cell number was reduced in all the cell lines suggesting that BP affects cell proliferation. In conclusion, a TP53 mutation does not necessarily lead to a loss of p53 protein response. This study stresses the importance of characterization of all human cancer cell lines for the intended targets of study.