Structure-Activity Relationships of a New Series of Retinoidal Benzoic Acid Derivatives as Measured by Induction of Differentiation of Murine F9 Teratocarcinoma Cells and Human HL-60 Promyelocytic Leukemia Cells

A new group of retinoids, which are 3-alkyl and 3-alkoxy derivatives of ( E )-4-[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-1-propenyl]-benzoic acid (TTNPB), has been synthesized. They were tested in vitro for biological activity by measuring induction of terminal differentiation in both murine F9 teratocarcinoma cells and human HL-60 promyelocytic leukemia cells. In the F9 assay, TTNPB was significantly more active (dose effective in achieving a half-maximal response, 3 × 10-9 m) than was all- trans -retinoic acid, while the 3-methyl derivative of TTNPB was not. However, in the HL-60 assay, the 3-methyl derivative of TTNPB was more active (dose effective in achieving a half-maximal response, 2 × 10-8m) than was all- trans -retinoic acid, while TTNPB was less active. 3-Ethyl and 3-propyl derivatives were much less active than was all- trans -retinoic acid in both assays. These new retinoids should be useful agents for experimental studies of both cancer prevention and treatment, as well as for investigation of the mechanism of action of retinoids in the control of cell differentiation.