beta-carotene stability and uptake by prostate cancer cells are dependent on delivery vehicle

Cell culture systems provide an opportunity to evaluate the effects of caro tenoids on molecular and cellular processes involved in proliferation and d ifferentiation of prostate cancer cells. The stability and cellular uptake of beta-carotene (BC) by prostate cancer cells were investigated in vitro b y use of various delivery methods and three human prostate adenocarcinoma c ell lines: PC-3, DU 145, and LNCaP. Recovery of BC from the media (prepared from water-dispersible BC beadlets) significantly (p < 0.05) decreased aft er 12 hours in culture and continued to significantly decrease (p < 0.05;) after 24, 48, 72, and 96 hours, an observation primarily attributed to BC d egradation rather than isomerization, metabolism, or cellular uptake. The u ptake of BC by prostate cancer cells was compared when delivered by tetrahy drofuran, BC-enriched bovine serum, water-dispersible BC beadlets, and arti ficial liposomes. Recovery of BC after three days in culture from enriched bovine serum medium was significantly (p < 0.05) greater than recovery from medium prepared by beadlets, tetrahydrofuran, or artificial liposomes. We conclude that BC is relatively unstable in vitro and that degradation produ cts may contribute to biological responses. Furthermore, our studies indica te that enriched bovine serum provides a stable and physiological approach to carotenoid treatment of cells in culture.