Most anticancer agents mediate their effects through common pathways which induce apoptosis or in some cases necrosis of cancer cells. The apoptotic pathways are regulated by Bcl-2 family proteins, which include both pro- and anti-apoptotic members. Much is known about the interactions of these proteins involved in apoptosis and this information is being utilized in the development of new reagents that may be used to treat patients with cancers. The inhibitor of apoptosis family of proteins constitute a second group of proteins which inhibit the effector caspases. Reagents that inhibit their activity are also under development. Resistance of cancer cells to treatment can in many instances be attributed to activation of intracellular signal pathways involved in survival, such as the Ras-Raf-MEK-ERK1/2 or the P13K-Akt pathway. Again, much has been learned about the control of these pathways and their activation of resistance mechanisms. Inhibitors of such pathways are being evaluated in preclinical and clinical studies and are showing promise as a new class of anticancer agents. Much of the progress in future studies will likely depend on the ability to target these new treatments to particular subgroups of patients with tumor characteristics that make them responsive to the agents in question.
International Review of Cytology: a Survey of Cell Biology Vol. 251, p. 131-158