Tetrazolium violet induces G0/G1 arrest and apoptosis in brain tumor cells

Tetrazolium violet induced apoptosis and cell cycle arrest in human lung cancer a549 cells

Tetrazolium violet is a tetrazolium salt and has been proposed as an antitumor agent. In this study, we reported for the first time that tetrazolium violet not only inhibited human lung cancer A549 cell proliferation but also induced apoptosis and blocked cell cycle progression in the G1 phase. The results showed that tetrazolium violet significantly decreased the viability of A549 cells at 5-15 μM. Tetrazolium violet -induced apoptosis in A549 cells was confirmed by H33258 staining assay. In A549, tetrazolium violet blocked the progression of the cell cycle at G1 phase by inducing p53 expression and further up-regulating p21/WAF1 expression. In addition, an enhancement in Fas/APO-1 and its two forms of ligands, membrane-bound Fas ligand (mFasL) and soluble Fas ligand (sFasL), as well as caspase, were responsible for the apoptotic effect induced by tetrazolium violet. The conclusion of this study is that tetrazolium violet induced p53 expression which caused cell cycle arrest and apoptosis. These findings suggest that tetrazolium violet has strong potential for development as an agent for treatment lung cancer.

Deriving TC50 values of nanoparticles from electrochemical monitoring of lactate dehydrogenase activity indirectly

Nanotoxicity assessment methods for nanoparticles (NPs) such as carbon nanotubes (CNTs), nano-Al(2)O(3), and tridecameric aluminum polycation or nanopolynuclear (nano-Al(13)), particularly lactate dehydrogenase (LDH) assays are reviewed. Our researches on electrochemically monitoring the variations of LDH activity indirectly in the presence of multiwalled carbon nanotubes (MWCNTs), nano-Al(13), and nano-Al(2)O(3) separately to derive toxic concentrations of NPs altering LDH activity by 50% (TC(50)) values are discussed. TC(50) values indicated that the toxicity order was Al (III)> MWCNTs > nano-Al(13) > nano-Al(2)O(3). Zeta potentials (ζ) data of these NPs in the literature proved that the surfaces of these NPs are charged negatively. Negatively charged surfaces might be a main cause in the reduction of LDH activity. Therefore, the classic LDH assays are doubtful to underestimate the nanotoxicities when they are applied to those NPs with negatively charged surfaces. These observations highlight and reconcile some contradictory results at present such as medium-dependent toxicity of NPs among the literature and develop novel analytical methods for evaluation of toxicities of NPs.

Tetrazolium violet inhibits cell growth and induces cell death in C127 mouse breast tumor cells

Tetrazolium violet (TV), a tetrazolium salt, has been applied in several fields, including estimating respiration rate, as a redox indicator of microbial growth, and for estimating the number of viable animal cells. It has recently been found that TV is capable of inducing apoptosis in rat glioblastoma cells by way of an elusive mechanism. In this study, we demonstrated that TV also induced apoptosis in mouse breast tumor C127 cells as evidenced by nucleus condensation and nucleus fragmentation. Our data showed that TV caused activation of caspase-3 and caspase-8, but not caspase-9. An enhancement in Fas and its two ligands, membrane-bound Fas ligand (mFasL) and soluble Fas ligand (sFasL), might be responsible for the apoptotic effect induced by TV. Also, the results first reported that TV not only inhibited C127 cells proliferation but also blocked cell cycle progression in the G1 and G2 phase, determined by MTT assay and flow cytometry analysis. Immunofluorescence assay demonstrated that TV significantly increased the expression of p53 protein, which caused cell cycle arrest. Taken together, p53, Fas/FasL, and the caspase apoptotic system may participate in the antiproliferative activity of TV in C127 cells.