Artificial analogs of naturally occurring tumor promoters as biochemical tools and therapeutic leads.

Tumor promoters are non-carcinogenic chemicals that enhance tumor formation when administered repeatedly after a low dose of a carcinogen. Phorbol esters, teleocidins, and aplysiatoxins are typical examples of naturally occurring tumor promoters. All of them share the ability to bind and activate protein kinase C (PKC) despite the differences in their chemical structures. A variety of analogs with unique chemical and biological properties have been developed to analyze the molecular mechanism of tumor promotion through PKC activation. Moreover, coupled with the emerging significance of PKC in the pathological processes of Alzheimer's disease (AD) and acquired immune deficiency syndrome (AIDS) as well as cancer, several efforts have been made recently to generate analogs of tumor promoters with therapeutic potential. This review focuses on artificial analogs of phorbol esters, teleocidins, and aplysiatoxins, and discusses their potential as biochemical tools and therapeutic leads.