Is induction of type 2 programmed death in cancer cells from solid tumors directly related to mitochondrial mass?

Many solid cancers respond to chemo or radiotherapy with a type 2 form of p rogrammed cell death. This requires direct participation of mitochondria wi th release of cytochrome c and other factors that activate the 'execution' phase of the process. It is believed that as solid cancers progress, less d ifferentiated clones containing fewer mitochondria evolve. Consequently, th e mitochondrial 'switch' that activates the type 2 process will become less effective, as the number of elements available and their mass-effect decli nes. The opportunity for successful therapy, considered to depend upon the ability to activate programmed cell death, therefore becomes progressively less probable. (C) 2001 Harcourt Publishers Ltd.