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Breast cancer patients negative for the nuclear oestrogen receptor α have a particularly poor prognosis. Therefore, the 4T1 cell line (considered as a triple-negative model) was chosen to induce malignancy in mice. The aim of the present study was to assess if zinc ions, provided in excess, may significantly modify the process of mammary oncogenesis. Zn(II) ions were chosen because of their docu- mented antitumour effects. Zn(II) is also known to induce the expression of metallothioneins (MT) and glutathion (GSH). A total dose of zinc sulphate per one gram of mouse weight used in the experiment was 0.15 mg. We studied the expression of MT1, MT2, TP53 and MTF-1 genes and also examined the effect of the tumour on antioxidant capacity. Tumour-free mice had significantly higher expression levels of the studied genes ( p

Differences in the antioxidant system, apoptotic mechanism and in cell cycle between prostatic cell lines could partially elucidate the development of cisplatin resistance. The aim of this study was to identify the most characteristic parameter for a particular cell line and/or a particular cisplatin treatment using a general regression model and to assess whether it is possible to use measured parameters as markers of cisplatin resistance. This study integrates the results of viability, antioxidant, flow cytometric and quantitative PCR assays in order to characterize the resistance of prostate cancer to cisplatin. Cell growth using metabolic- (MTT) and impedance-based assays, the expression of key cell death signaling proteins (p53, Bax and Bcl-2), cell cycle, activity of antioxidant system-related proteins (superoxide dismutase, glutathione peroxidase, glutathione reductase and metallothionein) and free radical scavenging capacity assays [free radicals (FR), ferric reducing antioxidant power (FRAP), ABTS] were analyzed in the cell lines 22Rv1, PC-3 and PNT1A with respect to rising concentrations (0-150 µM) and different length of cisplatin treatment (12-72 h). The non-functional-p53 PC-3 cell line showed decreased BAX (p0.05) and, in contrast to PNT1A and 22Rv1, no cisplatin-induced effects on cell cycle. All cell lines showed increasing levels of free radical scavenging activity by ABTS, FRAP and FR assays in a time- and dose-dependent manner (r0.76 at p0.001 for ABTS, FRAP and FR at p0.001). PC-3 showed increased (p0.05) levels of free radical scavenging activity by ABTS and FR methods. These findings, together with significantly elevated MT, decreased p53 and Bax indicate PC-3 to be cisplatin-resistant. The differences in the antioxidant system and apoptotic mechanisms in PC-3 cells may elucidate the development of cisplatin resistance and indicate that this cell line may be further studied as a model of cytostatic resistance.

Guinea pigs (Cavia porcellus) were treated with haloperidol (HP), and free radical (FR) and ferric reducing antioxidant power (FRAP) assays were used to determine oxidative stress levels. Furthermore, the superoxide dismutase (SOD), glutathione reductase (GR) and glutathione-S-trans- ferase (GST) activity levels were detected and glucose levels and the reduced and oxidized glutathione (GSH/GSSG) ratio were measured in HP-treated and untreated guinea pigs. The present study demonstrated that the administration of HP causes significant oxidative stress in guinea pigs (P=0.022). In animals treated with HP, the activity of GST was significantly increased compared with a placebo (P=0.007). The elevation of SOD and GR activity levels and increase in the levels of glutathione (GSH) in HP-treated animals were not statistically significant. In the HP‑untreated animals, a significant positive correlation was observed between oxidative stress detected by the FR method and GST (r=0.88, P=0.008) and SOD (r=0.86, P=0.01) activity levels, respectively. A significant negative correlation between the levels of plasma glucose and oxidative stress detected by the FRAP method was observed (r=‑0.78, P=0.04). Notably, no significant correlations were observed in the treated animals. In the HP-treated group, two subgroups of animals were identified according to their responses to oxida- tive stress. The group with higher levels of plasma HP had higher enzyme activity and reactive oxygen species production compared with the group with lower plasma levels of HP. The greatest difference in activity (U/µl) between the two groups of animals was for GR.

MicroRNAs (miRNAs) are a large class of single-stranded RNA molecules involved in post-transcriptional gene silencing. miRNAs not only regulate various developmental and physiological processes but also are involved in cancer development. Additionally, they can be considered as biomarkers of some pathological processes. The aim of this study was to determine the expression levels of selected miRNA and zinc(II)-related genes (ZIP-1, BAX, MT2A and MT1A) in the non-tumor PNT1A prostate cell line in comparison with the prostate cancer cell lines 22Rv1, PC-3 and LNCaP after zinc(II) treatment. Using bioinformatic approaches we selected miRNAs with putative binding sites in the 3'UTR regions in Metallothionein 1A and 2A as miRNA 23a, 141, 224, 296-3p, 320, 375 and 376. We observed significantly higher expression of miRNA 23a in all tumor lines compared to non-tumor PNT1A (13.6-fold in 22Rv1, 7.3-fold in PC-3, 8.3-fold in LNCaP, p0.01). We also observed that the 22Rv1 cell line has significantly higher expression of miRNA 224 in comparison to other cell lines. In addition, all tumor cell lines expressed significantly higher levels of miRNA 375 in comparison to non-tumor PNT1A (87.1‑fold in 22Rv1, nearly 2,000-fold in PC-3, 56.3‑fold in LNCaP, p0.01). Nevertheless, miRNA 375 and 23a expression levels strongly suggest their potential to contribute to the diagnosis of prostate cancer and miRNA 224 eventually may be suitable for classification of primary tumors. The expression of miRNA 224 in 22Rv1 cell line was negatively correlated with increasing zinc(II) concentration only. Our experiments revealed significant negative correlation of miRNA 376 and MT2A in 22Rv1 and a negative correlation between miRNA 224 and MT1A in PC-3 cells which may denote possible direct regulation of MT genes by specific miRNAs in prostate cancer.