Dose‐dependent induction of apoptosis in human tumour cell lines by widely diverging stimuli

Abstract

Cell death may occur by either of two mechanisms: apoptosis or necrosis. Necrosis, the first type of cell death to be recognized, is an uncontrolled degenerative phenomenon invariably caused by noxious stimuli and is the result of irreversible failure of membrane function. Apoptosis, on the other hand, is a death process which involves a series of well-organized events which require active cell participation, and is primarily caused by physiological stimuli. In the present study we show that cell death induced by a range of varied agents may take the form of either apoptosis or necrosis. Apoptotic cell death was found to occur at low levels of these agents, while at higher levels necrosis occurred. Hence, cells which are not killed directly, but merely injured by these agents, have the capacity to activate an internally programmed suicide death mechanism, whereas cells receiving greater injuries apparently do not. In addition, the presence of extracellular calcium was found to be necessary for the induction of apoptosis with all agents tested.

Evaluation of anti–apoptotic activity of different dietary antioxidants in renal cell carcinoma against hydrogen peroxide

“…Although apoptosis and necrosis have different impacts on cellular physiology, the cellular response to H 2 O 2 is continuing from apoptosis to necrosis [4] i.e. high concentration induces necrosis converse is applicable for apoptosis [3][4][5] .…”

Inhibition of mitochondrial respiratory chain complex I by TNF results in cytochrome c release, membrane permeability transition, and apoptosis

“…Additional mechanisms may be involved in TNF-induced cytotoxicity. Since mitochondria are the main source of ROS, which have been implicated in both apoptosis and necrosis (Lennon et al, 1991), mitochondriaderived ROS may provide a link between mitochondria and cell death. This hypothesis is also supported by the observation that under low oxygen conditions, TNF-induced cytotoxicity was reduced (Matthews et al, 1987).…”

Features of apoptotic cells measured by flow cytometry

“…In contrast to apoptosis, or programmed cell death, necrosis is a nonspecific mode of cell death, often caused by excessively high concentrations of toxic agents (36, 40,46,53). Necrosis, occurring as the result of rapid cell poisoning, is characterized by swelling of mitochondria and immediate loss of plasma membrane integrity.…”