Chemotherapeutically induced DNA damage, ATP depletion, and the apoptotic biochemical cascade.

The biochemical death cascade of apoptosis is separate from, although induced by, the anticancer drug-target interaction. The failure of many of our chemotherapeutic agents reflects an inability of anticancer drugs to induce apoptosis. Understanding the basic cellular mechanisms that control apoptosis will greatly increase our ability to treat cancer. Identification of the components of the apoptotic biochemical cascade will present new targets for complementary enhancement of chemotherapeutically induced cancer cell death. One factor that has been directly implicated in apoptosis is adenosine triphosphate (ATP). Nevertheless, in this regard, ATP is controversial. This commentary takes issue with dogma, and points to the need for additional thought and research in this field. ATP-depleting therapy of tumor-bearing mice has been shown to induce a marked therapeutic result with minimal mortality, and this effect can be further enhanced when combined with chemotherapy. The definitive mechanism of action is still controversial, although several mechanisms for ATP depletion have been implicated in the process. These include reduction in the mitochondrial transmembrane potential, activation of poly (ADP-ribose) polymerase (PARP) and depletion of the coenzyme nicotinamide adenine dinucleotide (NAD+). Even though the definitive experiments have yet to be carried out, the identification of ATP depletion as a critical determinant in apoptosis should allow for the development of new therapeutic strategies in the treatment of human cancer.