Bile Acid: Drivers, Carriers and Trojan Horses in Cancer Research

Composed of a steroid nucleus, widely distributed in the animal and plant kingdoms, containing various hydroxyl and methyl groups, and a carboxyl side chain, bile acids (BAs) appear to be the result of an irreversible evolution in nature. BAs are involved in numerous vital processes, such as enterohepatic circulation, recognition and transport by various proteins, and their role as “clients” of the farnesoid X receptor, suggesting that they could be used as carriers, transporters, or Trojan horses to deliver a drug to its target. Pioneers of this approach include Ehrlich, Ho, and Kramer, who conceived of “magic bullet” concepts and designed what are now known as conjugated BAs or drug–BA complexes. This review focuses on articles that apply these concepts to the broad and complex field of cancer research. Most of the reviewed studies follow a common trajectory encompassing the design and synthesis of BA conjugates, the in vitro evaluation of their anticancer activity in various cell lines, and their subsequent in vivo assessment. More than 250 compounds have been taken into consideration.