DL-ALPHA-TOCOPHEROL INDUCES APOPTOSIS IN ERYTHROLEUKEMIA, PROSTATE, AND BREAST-CANCER CELLS

Vitamin E, best known as a potent antioxidant, has been shown to have other functions that are not mediated by this activity. Recent reports have suggested that vitamin E may inhibit smooth muscle cell and also cancer cell growth. We have studied the effect of dl-alpha-tocopherol (vitamin E) on a series of well-established cancer cell lines that in cluded two erythroleukemia cell lines and a hormone-responsive breast and prostate cancer cell line. Cell proliferation was examined in thes e cell lines, which were maintained at optimal growth conditions. A do se-dependent inhibition of cell growth was found in all cell lines exa mined, with the MCF-7 breast and CRL-1740 prostate cancer cell lines s howing potent suppression of growth at 0.1 mM vitamin E, whereas the e rythroleukemia cell lines, HEL and OCIM-1, responded only at <0.25 mM vitamin E with inhibition of proliferation. Studies of [H-3]thymidine incorporation showed that vitamin E supplementation reduced DNA synthe sis in all cell lines. Analysis of high-molecular-weight DNA revealed extensive fragmentation, indicating apoptosis of all cell lines supple mented with vitamin E. Our studies thus give evidence of a general inh ibition of cell proliferation by dl-alpha-tocopherol, with breast and prostate cancer cells distinctly more sensitive than erythroleukemia c ells.