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Cadmium (Cd), a heavy metal with strong carcinogenic properties has been linked with breast cancer risk. Epidemiological data on the association between Cd exposure and breast cancer are not consistent and suggest that this relationship may be modulated by a number of different factors. The mechanisms of action underlying the molecular effects of Cd, especially in terms of its carcinogenicity, are generally not well understood. Specifically, in the mammary gland, the effects of Cd are considered to be related mainly to its oestrogenic potential, however, several other mechanisms have also been suggested, such as epigenetic alterations, inhibition of DNA repair pathways, induction of oxidative stress, interference with metallothioneins, cadherins and integrins, as well as interactions with xenobiotics. This review summarizes the current state of knowledge in this field, including potential mechanisms of action of Cd in breast cancer initiation and progression, as well as possible ways of protection against its toxicity. Importantly, there are many research gaps in this area since limited evidence is available from experimental studies. Important issues to be further investigated concern exact molecular mechanisms of Cd accumulation in the tissues and Cd-induced activation of eostrogen receptors. Impact on DNA damage and epigenome upon Cd exposure in breast cancer development remains still highly unexplored area and should gain more interest.

According to the precarious manhood perspective, masculinity threat triggers various compensatory mechanisms and heightens motivation to restore and reaffirm masculinity via typically masculine attitudes and behaviors. Four experiments aiming to examine the effect of masculinity threat on prejudices toward sexual and gender minorities were undertaken, controlling for adherence to sex role stereotypes. Our studies showed that Polish men representing university and high school students exposed to gender threat experienced increased negative affect (Experiment 1) and expressed higher prejudices toward gay people (Experiment 2) and transgender individuals (Experiments 3a and 3b). Furthermore, Experiment 2 revealed an effect of masculinity threat on modern prejudices predominantly toward gay people but not old-fashioned homonegativity. The results are discussed in terms of the role of masculinity threat as the mechanism responsible for gender differences in the attitudes toward sexual and gender minorities.

Data available on the genotoxicity of zinc oxide (ZnO) nanoparticles (NPs) are controversial. Here, we examined the effects of particle size and dispersion status on the cytotoxicity and genotoxicity of nanosized and fine ZnO, in the presence and absence of bovine serum albumin (BSA; 0.06%) in human bronchial epithelial BEAS-2B cells. Dynamic light scattering analysis showed the most homogenous dispersions in water alone for nanosized ZnO and in water with BSA for fine ZnO. After a 48-h treatment, both types of ZnO were cytotoxic within a similar, narrow dose range (1.5-3.0μg/cm(2)) and induced micronuclei at a near toxic dose range (1.25-1.75μg/cm(2)), both with and without BSA. In the comet assay, nanosized ZnO (1.25-1.5μg/cm(2)), in the absence of BSA, caused a statistically significant increase in DNA damage after 3-h and 6-h treatments, while fine ZnO did not. Our findings may be explained by better uptake or faster intracellular dissolution of nanosized ZnO without BSA during short treatments (3-6h; the comet assay), with less differences between the two ZnO forms after longer treatments (>48h; the in vitro micronucleus test). As ZnO is genotoxic within a narrow dose range partly overlapping with cytotoxic doses, small experimental differences e.g. in the dispersion of ZnO particles may have a substantial effect on the genotoxicity of the nominal doses added to the cell culture.

This study was undertaken to assess cytotoxic effects of selected aluminium compounds, parabens and phthalates in combination with silver nanoparticles (AgNP, 15 and 45 nm by STEM, Ag15 and Ag45, respectively) on cell lines of the human breast epithelium, normal (MCF-10A) and transformed (MDA-MB-231 and MCF-7). Combination indices were the most spectacular at effective concentrations (ED) inducing 25 % decrease in viability for the combinations of Ag15 with AlCl3 for MDA-MB-231 cells or aluminium zirconium tetrachlorohydrex Gly (AlZr) for MCF-10A and MCF-7 cells, where rather strong antagonism was revealed. As the ED values increased, those effects were enhanced (e.g. Ag15+AlCl3 for MDA-MB-231) or reversed into synergism (e.g. Ag15+AlZr for MCF-7). Another strong effect was observed for aluminium chloride hydroxide, which increasing ED, induced synergistic effect with both Ag15 and Ag45 on MCF-10A cells. Another interesting synergistic effect was observed for DBPh, but only in combination with Ag45 on MCF-10A and MCF-7. The results on cytotoxicity, cell cycle and oxidative stress induction indicate complex response of the cell lines to combined treatment with silver nanoparticles and the chemicals, which were influenced by diverse factors, such as physico-chemical characteristics of AgNP, method of their synthesis, concentrations used, and finally cell type.

In the study the modulating effect of inhibition of phosphatidylinositol 3-kinase-related kinases (PIKK): ATM (Ataxia Telangiectasia Mutated), ATR (Ataxia Telangiectasia and Rad3 Related) and DNA-PK (DNA-dependent protein kinase) on genotoxicity of dibenzo[def,p]chrysene (DBC) in HepG2 human hepatocellular cancer cells was investigated. The cytotoxicity of DBC was determined, also in combination with PIKK inhibitors, using the MTT reduction assay. The high cytotoxicity of DBC was observed after 72 h incubation (IC50 = 0.06 μM). The PIKK inhibitors applied at non-cytotoxic concentrations: caffeine (1 mM) and KU55933 (2.5 μM) had no significant influence on the DBC cytotoxicity, however NU7026 (5 μM) caused significant increase in the cell viability by about 25%. The combinations of the inhibitors (double or triple) where NU7026 was present also caused increase in the cell viability (i.e. cytoprotective effect) compared to the effect of DBC. The level of damage to the genetic material (DNA double strand breaks, DSB) was assessed by measuring levels of phosphorylated form of H2A histone (γH2AX) and neutral comet assay. DBC induced DSB in a concentration and time-dependent manner. NU7026 considerably reduced the level of DSB level measured by γH2AX and comet assay. The obtained results confirm that DBC is cytotoxic and causes damage to the genetic material including DSB. The DNA-PK inhibitor NU7026 increases cell viability after exposure to DBC and reduces DNA damage, what indicates an important role of the sensor kinase in mediating the effect.

Arsenic trioxide (ATO) is a well-recognized antileukemic drug used for the treatment of newly diagnosed and relapsed acute promyelocytic leukemia (APL). A major drawback of therapy with ATO is the development of APL cell resistance, the mechanisms of which are still not clear. The aim of this study was to investigate the role of the PI3K/Akt signaling pathway in ATOtreated human acute myeloid leukemia (HL-60) cells and in ATO-resistant clones. The cytotoxicity of ATO was assessed using Trypan blue staining or a WST-1 reduction assay. The Akt phosphorylation level was measured by immunofluorescent staining and flow cytometry. Gene expression analysis was performed using real-time polymerase chain reaction (PCR). The clones derived by culturing for 8-12 weeks in the presence of 1.75, 2.5, and 5 μM ATO were characterized by high viability but a slower growth rate compared to the parental HL-60 cells. The flow cytometry analysis showed that in the parental cells the levels of p-Akt were undetectable or very low, and that ATO had no effect on the level of p-Akt in either the ATO-treated parental cells or the clones. The gene expression analysis revealed that some of the genes involved in the Akt pathway may play a key role in the induction of resistance to ATO, e.g., genes encoding cyclin D1 (CCND1), fork head box O1 (FOXO1), Jun oncogene (JUN), protein kinase C isoform B1 (PRKCB1), because their expression profiles were predominantly changed in the clones and/or the ATO-treated parental HL-60 cells. The overall results indicate that CCND1, FOXO1, and JUN may contribute to the induction of resistance to ATO, and that the C-Jun N-terminal kinase (JNK) signaling pathway may have greater significance than the phosphoinositide 3-kinase (PI3K)/Akt pathway in mediating the cytotoxic effects of ATO and the development of resistance to ATO in the HL-60 cell line. This research was supported by grant N N401 2806 33 (agreement 2806/B/P01/2007/33) from the Polish Ministry of Science and Higher Education

In this study the effect of silver nanoparticles (AgNPs) on proliferation of estrogen receptor (ER)-positive human breast cancer MCF-7/BUS cells was assessed by means of in vitro assay. The cells were exposed in the absence of estrogens to AgNPs alone or in combination with aluminum chloride (AlCl3), butyl paraben (BPB) and di-n-butyl phthalate (DBPh). The results revealed that AgNPs at the non-cytotoxic concentrations (up to 2μg/mL) and AlCl3 (up to 500μM) did not induce proliferation of MCF-7/BUS cells whereas BPB and DBPh showed strong estrogenic activity with the highest effect at 16μM and 35μM, respectively. AgNPs inhibited the proliferation of the cells induced by DBPh, BPB or even with 17β-estradiol (E2) during 6-day incubation in the absence of estrogens. ICI 182,780 (10nM), a known estrogen receptor (ER) antagonist, induced strong inhibitory effect. AgNPs also decreased transcription of the estrogen-responsive pS2 and progesterone receptor (PGR) genes but modulated expression neither of ERα nor ERβ in MCF-7/BUS cells exposed to BPB, DBPh or E2 for 6h. Our results indicate that AgNPs may inhibit growth of breast cancer cells stimulated by E2 or estrogenic chemicals, i.e. BPB and DBPh.

In this study the role of PI3K/Akt signaling pathway in arsenic trioxide (ATO)-treated parental Jurkat cells and also in derived ATO-resistant clones grown in the presence of given ATO concentration was investigated. ATO-resistant clones (cultured for 8-12weeks in the presence of 1, 2.5 and 5μM ATO) were characterized by high viability in the presence of ATO but slower growth rate compared to the parental cells. Morphological and functional characterization of derived ATO-resistant clones revealed that they did not differ fundamentally from parental Jurkat cells in terms of cell size, level of GSH, the lysosomal fluorescence or CD95/Fas surface antigen expression. However, a slight increase in the mitochondrial potential (JC-1 staining) was detected in the clones compared to parental Jurkat cells. Side population analysis (Vybrant DyeCycle Violet™ staining) in ATO resistant clones did not indicate any enrichment withcancer stem cells. Akt1/2, AktV or wortmannin inhibitors decreased viability of ATO-resistant clones grown in the presence of ATO, with no effect on ATO-treated parental cells. Flow cytometry analysis showed that ATO decreased the level of p-Akt in ATO-treated parental cells, while the resistant clones exhibited higher levels of p-Akt immunostaining than parental Jurkat cells. Expression analysis of 84 genes involved in the PI3K/Akt pathway revealed that this pathway was predominantly active in ATO-resistant clones. c-JUN seems to play a key role in the induction of cell death in ATO-treated parental Jurkat cells, as dose-dependent strong up-regulation of JUN was specific for the ATO-treated parental Jurkat cells. On the other hand, changes in expression of cyclin D1 (CCND1), insulin receptor substrate 1 (IRS1) and protein kinase C isoforms (PRKCZ,PRKCB and PRKCA) may be responsible for the induction of resistance to ATO. The changes in expression of growth factor receptor-bound protein 10 (GRB10) observed in ATO-resistant clones suggest a possibility of induction of different mechanisms in development of resistance to ATO depending on the drug concentration and thus involvement of different signaling mediators.

The effect of inhibitors of phosphatidylinositol-3-kinase-related kinases (PIKK): ataxia-telangiectasia mutated (ATM), ATM- and Rad3-related (ATR) and DNA-dependent protein kinase (DNA-PK) on response of HepG2 human liver cancer cells to benzo[a]pyrene (BaP) was investigated. PIKK inhibitors: KU55933 (5 μM), NU7026 (10 μM) or caffeine (1 and 2mM) when used as single agents or in combinations (KU55933/NU7026 and caffeine/NU7026) did not significantly influence the BaP (3 μM) cytotoxicity (MTT reduction test). BaP induced a weak proapoptotic effect which was moderately enhanced by both inhibitor combinations. HepG2 cells exposed to BaP showed a strong S-phase arrest which was considerably diminished by both inhibitor combinations. The DNA damage (comet assay) induced after continuous 24h exposure to BaP was significantly diminished by both inhibitor combinations. Weak induction of reactive oxygen species by BaP was observed, which was not modulated by the inhibitor combinations. Similarly, no modulation of the glutathione levels was observed.

Synthetic amorphous silica nanomaterials (SAS) are extensively used in food and tire industries. In many industrial processes, SAS may become aerosolized and lead to occupational exposure of workers through inhalation in particular. However, little is known about the in vivo genotoxicity of these particulate materials. To gain insight into the toxicological properties of four SAS (NM-200, NM-201, NM-202, and NM-203), rats are treated with three consecutive intratracheal instillations of 3, 6, or 12 mg/kg of SAS at 48, 24, and 3 hrs prior to tissue collection (cumulative doses of 9, 18, and 36 mg/kg). Deoxyribonucleic acid (DNA) damage was assessed using erythrocyte micronucleus test and the standard and Fpg-modified comet assays on cells from bronchoalveolar lavage fluid (BALF), lung, blood, spleen, liver, bone marrow, and kidney. Although all of the SAS caused increased dose-dependent changes in lung inflammation as demonstrated by BALF neutrophilia, they did not induce any significant DNA damage. As the amount of SAS reaching the blood stream and subsequently the internal organs is probably to be low following intratracheal instillation, an additional experiment was performed with NM-203. Rats received three consecutive intravenous injections of 5, 10, or 20 mg/kg of SAS at 48, 24, and 3 hrs prior to tissue collection. Despite the hepatotoxicity, thrombocytopenia, and even animal death induced by this nanomaterial, no significant increase in DNA damage or micronucleus frequency was observed in SAS-exposed animals. It was concluded that under experimental conditions, SAS induced obvious toxic effects but did cause any genotoxicity following intratracheal instillation and intravenous injection.