Prognostic Value of MicroRNA-203a Expression in Breast Cancer

Tumor heterogeneity and the poor outcome of breast cancer (BC) patients have led researchers to define new markers of this disease. In recent years, microRNA expression patterns have proven to be valuable disease indicators. The level of miR-203a, in particular, was shown to be altered in different types of cancer. The objective of the present study was to assess the relationship between miR-203a expression and clinicopathological features of BC in a Portuguese cohort. The expression levels of miR‑203a were analyzed in 109 formalin‑fixed paraffin-embedded paired normal and tumor tissue samples. Significant overexpression of miR‑203a in the tumor tissues was found (1.7-fold higher) compared to the expression in the normal adjacent tissues (p=0.003). In addition, several clinicopathological characteristics presented an association with higher miR-203a expression levels. Tumors with diameter ≤18.5 mm (1.5-fold; p=0.019), tumors positive for estrogen receptor (fold-change, 1.71; p=0.042), progesterone receptor (fold-change, 1.50; p=0.046) and negative for HER2 (fold-change, 1.50; p=0.016) and high Ki-67 index (fold-change, 2.60; p=0.024) presented a significant difference in miR-203a expression compared with adjacent normal tissues. Tumors without invasion of lymph nodes also presented higher expression of miR-203a (fold-change, 2.40; p=0.004). With regard to histological classification, ductal carcinomas in situ (fold-change, 2.20; p=0.028) and invasive carcinoma NOS (fold-change, 1.71; p=0.009) displayed significantly higher expression of miR-203a. Moreover, we found a significant downregulation of miR-203a with increased stage in invasive lobular carcinomas, suggesting that miR-203a could represent a potential marker to discriminate stages in invasive lobular carcinomas.info:eu-repo/semantics/publishedVersio

Coronin-1A Links Cytoskeleton Dynamics to TCRαβ-Induced Cell Signaling

Actin polymerization plays a critical role in activated T lymphocytes both in regulating T cell receptor (TCR)-induced immunological synapse (IS) formation and signaling. Using gene targeting, we demonstrate that the hematopoietic specific, actin- and Arp2/3 complex-binding protein coronin-1A contributes to both processes. Coronin-1A-deficient mice specifically showed alterations in terminal development and the survival of αβT cells, together with defects in cell activation and cytokine production following TCR triggering. The mutant T cells further displayed excessive accumulation yet reduced dynamics of F-actin and the WASP-Arp2/3 machinery at the IS, correlating with extended cell-cell contact. Cell signaling was also affected with the basal activation of the stress kinases sAPK/JNK1/2; and deficits in TCR-induced Ca2+ influx and phosphorylation and degradation of the inhibitor of NF-κB (IκB). Coronin-1A therefore links cytoskeleton plasticity with the functioning of discrete TCR signaling components. This function may be required to adjust TCR responses to selecting ligands accounting in part for the homeostasis defect that impacts αβT cells in coronin-1A deficient mice, with the exclusion of other lympho/hematopoietic lineages

Lipoperoxidation products and thiol antioxidants in chromium exposed workers

Hexavalent chromium is an established carcinogenic agent, which is not directly reactive with DNA. Its genotoxicity involves a reduction step, producing reactive oxygen species and radicals, and also lower valence forms which form stable complexes with intracellular macromolecules. The trivalent form of chromium may directly react with the genetic material and has also been shown to generate oxidative damage in vitro. To further evaluate the importance of in vivo oxidative DNA damage in the toxicity of each valence form, we conducted a comparative study on hexavalent and trivalent chromium-exposed workers (manual metal arc stainless steel welders and leather tanning workers), focusing on the total oxidative status by quantifying the level of lipoperoxidation products in urine. Thiol antioxidants are important in response to oxidative stress, and therefore, the concentration of glutathione and cysteine in peripheral blood lymphocytes was also determined. Chromium exposure was evaluated by quantifying total chromium in plasma and urine. Both groups had a signficant increase in lipid peroxidation products expressed as malondialdehyde (MDA) in urine (tanners 1.42 +/- 0.61 mu mol/g creatinine, welders 1.67 +/- 1.13 mu mol/g creatinine versus controls 0.81 +/- 0.26 mu mol/g creatinine, P 0.005 in both cases) but only welders had a significant decrease in glutathione concentration in lymphocytes. There was a positive correlation between chromium in plasma and urinary MDA in welders, but not in tanners. This work is part of a larger study of which major results have been published previously including cytogenetics and DNA-protein cross-links in workers exposed to the two different forms of chromium. These results are compared with the results of oxidative damage from this study

Elevated levels of DNA-protein crosslinks and micronuclei in peripheral lymphocytes of tannery workers exposed to trivalent chromium

DNA-protein crosslinks (DPC) are a promising biomarker of exposure to hexavalent chromium, a known human carcinogen. Although trivalent chromium is considered to have much lower toxicity, the risk involved in chronic exposure is uncertain. DPC may be a useful tool in clarifying this risk, by signaling an exposure of body tissues to biologically active forms of chromium. DPC quantification was carried out in lymphocytes of a group of tannery workers exposed to trivalent chromium, a small group of manual metal arc stainless steel welders exposed to hexavalent chromium and a control group. This biomarker was compared with the frequency of micronuclei in cytokinesis blocked peripheral lymphocytes as a biomarker of cytogenetic lesions and total plasma and urine chromium levels as an index of exposure. The results indicate a significant increase in the formation of DPC in tannery workers compared with controls (0.88 +/- 0.19 versus 0.57 +/- 0.21%, P 0.001, Mann-Whitney test) and an even higher level of DPC in welders (2.22 +/- 1.12%,

Assessment of the adaptive response induced by quercetin using the MNCB peripheral blood human lymphocytes assay

Over more than two decades the existence of an adaptive response (AR) has been reported in several cell types and extensively studied with low doses of radiation. Besides radiation, some chemicals [alkylating compounds, mitomycin C (MMC), bleomycin, hydrogen peroxide and metals] may also induce an adaptive response. We have recently reported that the food mutagen quercetin can also induce an adaptive response in V79 Chinese hamster cells. In this work we have studied the effect of low doses of quercetin on the genotoxicity of MMC and bleomycin assessed by the formation of micronuclei in cytokinesis-blocked (MNCB) human peripheral blood lymphocytes. Our results suggest the existence of an AR induced by quercetin in human lymphocytes. Seven of the nine donors studied showed in at least one independent experiment a significant decrease in the frequency of MNCB induced by MMC. The range of these decreases varied between 31 and 58%. In addition, we observed an AR induced by quercetin towards challenging doses of bleomycin. In accordance with other studies with ionizing radiation in which heterogeneity of the AR in the population has been extensively observed, the response here reported also showed some degree of variability between the different donors studied. In view of the results obtained one cannot rule out a possible protective effect of low doses of quercetin leading to adaptation to further exposure to mutagens or carcinogens

DNA-PK inhibitor wortmannin enhances DNA damage induced by bleomycin in V79 Chinese hamster cells

The fungal metabolite wortmannin (WM) is a potent and irreversible inhibitor of the enzyme DNA-dependent protein kinase (DNA-PK), a nuclear serine-threonine kinase, member of the phosphaditylinositol-3 kinase related kinase family. WM has been used in the last few years as a promising radiosensitizer mainly throughout cell survival experiments. However, few studies have addressed the role of DNA-PK inhibition in the repair of DNA lesions generated by antitumor agents, Bleomycin (BLM) is an antitumor agent used in the treatment of various neoplasia with a unique genotoxicity profile that mimics the ionizing radiation effects. In this study, we evaluated the effect of different concentrations of WM on the DNA damage induced by BLM, The cytokinesis-block micronucleus assay (CBMN) in V79 Chinese hamster cells was used as the end-point, WM significantly increased the frequency of micronucleated cells (%MNBN) by about 2.2-fold, the number of micronuclei per binucleated cell (MN/BN) by about 14-fold, and also changed the pattern of the distribution of micronuclei induced by BLM, The frequency of micronucleated cells with 2 MN per cell and with greater than or equal to3 MN per cell increased, whereas the frequency of micronucleated cells with 1 MN per cell decreased. WM was not genotoxic but decreased cell proliferation as assessed by the frequency of binucleated cells. Our results show that WM clearly enhances the efficacy of BLM in terms of DNA damage inflicted and therefore reinforces its use as a chemosensitizer. (C) 2002 Wiley-Liss, Inc

Effect of poly(ADP-ribosyl)ation inhibitors on the genotoxic effects of the boron neutron capture reaction

The boron neutron capture (BNC) reaction results from the interaction of B-10 with low-energy thermal neutrons and gives rise to highly damaging lithium and alpha-particles. In this work the genotoxicity caused by the BNC reaction in V79 Chinese hamster cells was evaluated in the presence of poly(ADP-ribosyl)ation inhibitors. Poly(ADP-ribose) polymerase-1 (PARP-1), the most important member of the PARP enzyme family, is considered to be a constitutive factor of the DNA damage surveillance network present in eukaryotic cells, acting through a DNA break sensor function. Inhibition of poly(ADP-ribosyl)ation was achieved with the classical compound 3-aminobenzamide (3-AB), and with two novel and very potent inhibitors, 5-aminoisoquinolinone (5-AIQ) and PJ-34. Dose-response increases in the frequencies of aberrant cells excluding gaps (%ACEG) and chromosomal aberrations excluding gaps per cell (CAEG/cell) were observed for increasing exposures to the BNC reaction. The presence of 3-AB did not increase the %ACEG or CAEG/cell, nor did it change the pattern of the induced chromosomal aberrations. Results with 5-AIQ and PJ-34 were in agreement with the results obtained with 3-AB. We further studied the combined effect of a PARP inhibitor and a DNA-dependent protein kinase (DNA-PK) inhibitors (3-AB and wortmannin, respectively) on the genotoxicity of the BNC reaction, by use of the cytokinesis-block micronucleus assay. DNA-PK is also activated by DNA breaks and binds DNA ends, playing a role of utmost importance in the repair of double-strand breaks. Our results show that the inhibition of poly(ADP-ribosyl)ation does not particularly modify the genotoxicity of the BNC reaction, and that PARP inhibition together with a concomitant inhibition of DNA-PK revealed barely the same sensitizing effect as DNA-PK inhibition per se. (c) 2005 Published by Elsevier B.V