Effect of N-(4-hydroxyphenyl)retinamide on apoptosis in human breast cancer cells.

The synthetic retinoid N-(4-hydroxyphenyl)retinamide (4-HPR) has been used in breast cancer prevention and treatment. However, the molecular mechanisms mediating the effects of 4-HPR remain elusive. In the present study, we examined the effects of 4-HPR on components of apoptosis pathway (i.e Bcl-2 and Bax) and apoptotic death in both estrogen receptor-positive and estrogen receptor-negative cell lines. We found that: (1) 4-HPR treatment resulted in decreased Bcl-2 mRNA but not Bax mRNA levels; (2) the effect of 4-HPR on Bcl-2 mRNA level was different from other retinoids; (3) 4-HPR treatment induced apoptosis in both estrogen receptor-positive and -negative cells. Hence, the breast cancer chemopreventive properties of 4-HPR may involve modulation of apoptosis pathways.