Discovery Of New Mechanism Of Action For PARP Inhibitors

[gdpawel]

This new "NIH research discovery" brings up an interesting subject. While apoptosis represents an important mechanism of programmed cell death, it is only one of several cell death pathways.

Apoptotic cell death occurs with certain mutational events, DNA damage, oxidative stress and withdrawal of some growth factors particularly within the immune system.

Non-apoptotic programmed cell death includes: programmed necrosis, para-apoptosis, autophagic cell death, nutrient withdrawal, and subtypes associated with mis-folded protein response, and PARP mediated cell death.

While apoptotic cell death follows a recognized cascade of caspase mediated enzymatic events, non-apoptotic cell death occurs in the absence of caspase activation.

While caspase activation is of interest, comparably easy to measure and useful in many leukemias and lymphomas, it does not represent cancer cell death in all circumstances and can be an unreliable parameter in many solid tumors.

Labs that focus on measurements of caspase activation can only measure apoptotic cell death. While apoptotic cell death is of importance in hematologic cancers and some solid tumors, it does not represent the mechanism of cell death in all tumors.

This is why functional profiling measures all cell death events by characterizing metabolic viability at the level of cell membrane integrity, ATP content, or mitochondrial function.