QPy-TPA

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.

Apoptosis is a regulated, generally non-lytic cell-death pathway that removes unwanted, damaged, infected, or abnormal cells through coordinated morphological changes, caspase activation, DNA fragmentation, and membrane remodeling. The intrinsic apoptosis pathway is controlled mainly by mitochondrial outer membrane permeabilization, BCL-2 family proteins, cytochrome c release, apoptosome formation, caspase-9 activation, and downstream executioner caspase-3/7 activation. The extrinsic apoptosis pathway is initiated by death receptors such as Fas, TNFR, and TRAIL receptors, which recruit adaptor proteins and activate caspase-8 before engaging executioner caspases or mitochondrial amplification through BID cleavage. Apoptosis is linked to many phenotypes, including cancer cell killing, tissue homeostasis, immune regulation, neurodegeneration, infection response, and treatment-induced cytotoxicity; unresolved questions include how apoptosis interacts with necroptosis, pyroptosis, ferroptos

Ferroptosis is an iron-dependent, non-apoptotic form of regulated cell death characterized by lethal lipid peroxidation and sensitivity to suppression by iron chelators or lipophilic radical-trapping antioxidants. The core pathway links cystine uptake through system Xc−, glutathione availability, GPX4-dependent detoxification of phospholipid hydroperoxides, iron-dependent oxidative reactions, and polyunsaturated-phospholipid metabolism into a cell-death program that is biochemically and morphologically distinct from apoptosis, necrosis, and autophagy. The ferroptosis pathway is experimentally linked to phenotype through chemical and genetic perturbation. Erastin induces ferroptosis by inhibiting cystine uptake through system Xc− and weakening antioxidant defenses, while GPX4 inhibition or depletion causes lipid peroxide accumulation and ferroptotic cancer-cell death. ACSL4 and oxidizable arachidonoyl- or adrenoyl-containing phosphatidylethanolamines shape ferroptosis sensitivity by con