MICROTUBULE STABILIZATION AND POTENTIATION OF TAXOL ACTIVITY BY THE CREATINE ANALOG CYCLOCREATINE

Creatine kinase (CK), a key enzyme of cellular energetics, has been im plicated in tumorigenesis. Cyclocreatine (CCr), which forms a stable p hosphagen with a reduced rate of ATP regeneration through CK, inhibits the growth of many solid tumors. We report that CCr induces the forma tion of unusually stable microtubules that resist depolymerization by nocodazole. By reducing ATP availability, CCr may modulate the activit y of kinases that regulate microtubule dynamics. Further, combinations of CCr and taxol resulted in the synergistic killing of breast tumor cells indicating that CCr may be a useful addition to chemotherapy's t hat include taxanes.