Subcellular accumulation of beta-carotene and retinoids in growth-inhibited NCI-H69 small cell lung cancer cells.

Delivery of beta-carotene in tetrahydrofuran slowed the growth of NCI-H69 small cell lung cancer cells. Analysis of cells and cellular fractions revealed that beta-carotene-treated cells accumulated beta-carotene as well as some polar metabolites, primarily in the crude nuclei. Cells were grown at 1 x 10(5) cells/ml and treated with 20 microM beta-carotene. Growth monitoring up to 15 days indicated an inverse relationship between the duration of beta-carotene treatment and the rate of cell growth. Reverse-phase high-performance liquid chromatography analysis of treated cells showed the presence of beta-carotene, retinoic acid, retinol, and retinal, with beta-carotene accounting for the major material recovered. When cellular fractions were analyzed for beta-carotene, it was found to be located primarily in the crude nuclei. These results demonstrate that treatment of small cell lung cancer cells with beta-carotene results in a reduced growth of the cells. Further investigation is required to show a direct effect of beta-carotene or its intracellular polar metabolites on these cells. Accumulation of beta-carotene in the nucleus suggests a need for evaluating the nuclear role for beta-carotene.