BackgroundDespite advances in diagnostic and treatment strategies, head and neck squamous cell cancer (HNSCC) constitutes one of the worst cancer types in terms of prognosis. PTEN is one of the tumour suppressors whose expression and/or activity have been found to be reduced in HNSCC, with rather low rates of mutations within the PTEN gene (6-8%). We reasoned that low expression levels of PTEN might be due to a transcriptional repression governed by an oncogene. Tbx2 and Tbx3, both of which are transcriptional repressors, have been found to be amplified or over-expressed in various cancer types. Thus, we hypothesize that Tbx3 may be over expressed in HNSCC and may repress PTEN, thus leading to cancer formation and/or progression.MethodsUsing immunohistochemistry and quantitative PCR (qPCR), protein and mRNA levels of PTEN and Tbx3 were identified in samples excised from cancerous and adjacent normal tissues from 33 patients who were diagnosed with HNSCC. In addition, HeLa and HEK cell lines were transfected with a Tbx3 expressing plasmid and endogenous PTEN mRNA and protein levels were determined via qPCR and flow cytometry. Transcription assays were performed to demonstrate effects of Tbx3 on PTEN promoter activity. Mann–Whitney, Spearman’s Correlation and Wilcoxon signed-rank tests were used to analyze the data.ResultsWe demonstrate that in HNSCC samples, Tbx3 mRNA levels are increased with respect to their normal tissue counterparts (p<0.001), whereas PTEN mRNA levels are significantly reduced in cancer tissues. Moreover, Tbx3 protein is also increased in HNSCC tissue sections. Over-expression of Tbx3 in HeLa and HEK cell lines causes reduction in endogenous PTEN mRNA and protein levels. In addition, transcription activity assays reveal that Tbx3 is capable of repressing both the basal and induced promoter activity of PTEN.ConclusionsWe show that Tbx3 is up-regulated in tissue samples of HNSCC patients and that Tbx3 represses PTEN transcription. Thus, our data not only reveals a new mechanism that may be important in cancer formation, but also suggests that Tbx3 can be used as a potential biomarker in cancer.
In this study a genotoxic evaluation of titanium dioxide (TiO2, 2.3 nm), zirconium oxide (ZrO2, 6 nm), aluminum oxide (Al2O3, 16.7 nm) nanoparticles (NP) and their ionic forms was conducted using human peripheral blood lymphocytes and cultured human embryonic kidney (HEK293) cells by means of a modified alkaline comet assay with/without the formamidopyrimidine-DNA glycosylase (Fpg) and endonuclease III (Endo III) enzymes. Modifications to the comet assay by using lesion-specific endonucleases, such as Endo III and Fpg, detect DNA bases with oxidative damage. Both human peripheral blood lymphocytes and cultured embryonic kidney cells were incubated with TiO2, ZrO2, or Al2O3 NP at concentrations of 1, 10, or 100 μg/ml. Our results showed no significant induction in DNA damage by the comet assay with/without the Endo III and Fpg enzymes at all concentrations of ZrO2 and Al2O3. In the case of TiO2 NP only the highest concentration of 100 μg/ml significantly induced a genotoxic response. Data thus indicate that both ZrO2 and Al2O3 NP were not genotoxic in our system and in the case of TiO2 the lowest-observed-adverse-effect level (LOAEL) for genotoxicity was 100 μg/ml. Evidence indicates that these metallic NP are considered safe in light of the fact that no genotoxicity was noted with ZrO2 and Al2O3 and that the highest TiO2 concentration is not environmentally relevant.
Our aim was to investigate whether trans-resveratrol (t-resveratrol), a red wine constituent known for its cardioprotective effects, was able to influence CD40 ligand (CD40L) and its receptor CD40 in platelets of hypercholesterolemic rats. Sixty Wistar rats were divided into 5 groups: control (C), ethanol (E), t-resveratrol (R), hypercholesterolemia (HC), and hypercholesterolemia plus t-resveratrol (HCR). Rats in the C, E, and R groups were fed a normal diet for 80 days. For 20 days before sacrifice, we intraperitoneally (i.p.) administered 0.1 mL ethanol (50% v/v) to the E group, and 0.1 mL t-resveratrol (20 mg·kg(-1)·day(-1)) to the R group. Rats in the HC and HCR groups were fed a 5% cholesterol diet for 80 days. Rats in the HCR group were administered i.p. 0.1 mL t-resveratrol (20 mg·kg(-1)·day(-1)) for 20 days before sacrifice. Serum levels of total cholesterol (TC), low-density lipoprotein (LDL-C), high-density lipoprotein (HDL-C), very low-density lipoprotein (VLDL-C), and total triglycerides (TG) were assayed with a commercial colorimetric kit. Platelet P-selectin, CD40, and CD40L expression was determined by flow cytometry. sCD40L and IL6 levels were measured by ELISA. In the HC group, we observed a significant increase in serum TC, LDL-C, VLDL-C, TG, sCD40, and IL-6 levels and platelet activation markers compared with levels in the control group. However, t-resveratrol administration to the HC group (HCR group) attenuated the increase in lipids, sCD40, and IL-6 and down-regulated platelet P-selectin, CD40, and CD40L expressions. A positive correlation was found for serum lipids and all the platelet activation markers. Our study showed that the CD40-CD40L dyad is up-regulated in the presence of hypercholesterolemia and that t-resveratrol administration down-regulated the increase.
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