UM4118

Cytotoxicity assays are usually based on the assessment of cell membrane damage, which can also be indirectly detected by measuring cell viability. Detection methods include MTT assay, CKK-8 assay, LDH assay and ATP assay, etc.

Live/dead viability and cytotoxicity staining assays are based on the simultaneous detection of intracellular esterase activity in metabolically active (viable) cells and membrane integrity loss in non-viable cells. In commonly used dual-staining approaches, membrane-permeant fluorogenic substrates are converted by intracellular esterases into fluorescent products in live cells, while impermeant DNA-binding dyes selectively enter cells with compromised plasma membranes and label nucleic acids in dead or dying cells, enabling discrimination between viable and non-viable populations by fluorescence microscopy or flow cytometry.

The bacterial reverse mutation assay detects point mutations that restore amino-acid prototrophy in auxotrophic Salmonella typhimurium or Escherichia coli tester strains; after exposure to a test article, mutagenic activity is read out as an increased number of revertant colonies on minimal agar compared with the vehicle control. The assay uses tester strains with different mutation targets so that base-substitution and frameshift mutagens can be detected, and testing is performed with and without exogenous mammalian metabolic activation because some chemicals require biotransformation to become mutagenic.

Cuproptosis is a copper-dependent regulated cell-death pathway in which intracellular copper binds lipoylated tricarboxylic acid cycle proteins, especially DLAT-containing pyruvate dehydrogenase complex components, causing lipoylated protein aggregation, iron-sulfur cluster protein loss, proteotoxic stress, and cell death. The pathway is functionally linked to mitochondrial respiration because copper-ionophore sensitivity is higher in cells dependent on oxidative phosphorylation, and FDX1 and protein lipoylation machinery are required for copper-ionophore-induced death. Elesclomol-Cu and related copper-loading strategies are widely used experimental tools to induce cuproptosis, whereas copper chelation with tetrathiomolybdate or genetic suppression of FDX1, LIAS, LIPT1, or DLAT can test pathway dependence. The major unresolved questions are how disease context determines cuproptosis sensitivity, how copper transporters such as SLC31A1/CTR1 and ATP7A/ATP7B regulate the pathway, and whic

The following protocol uses the MTT colorimetric assay as a classic literature-established method for assessing cell viability/metabolic activity in cultured mammalian cells. MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] is reduced by metabolically active cells to a colored formazan product; the amount of formazan is quantified spectrophotometrically and provides an indirect measure of metabolically active viable cells. Importantly, MTT reduction reflects cellular oxidoreductase/metabolic activity rather than an absolute direct count of living cells, so changes in cellular metabolism can alter the signal independently of cell number.