Inhibitory effects of alpha-carotene on proliferation of the human neuroblastoma cell line GOTO.

alpha-Carotene inhibited the proliferation of the human neuroblastoma cell line GOTO in a dose- and time-dependent manner. In addition, it was about 10 times more inhibitory than beta-carotene. Northern blot analysis indicated that alpha-carotene caused maximum suppression of the level of the N-myc messenger RNA of GOTO cells. This suppression occurred within 18 hours of alpha-carotene treatment, after which the level of the N-myc messenger RNA gradually recovered to the basal level. Analysis by flow cytometry indicated that when GOTO cells were exposed to alpha-carotene, they were arrested in the G0-G1 phase of their cell cycle. However, as the level of the N-myc messenger RNA was recovering, these cells resumed normal cycling. These results indicate that the reduction in the level of the N-myc messenger RNA caused by alpha-carotene is closely linked with G0-G1 arrest.