dl‐α‐tocopherol induces apoptosis in erythroleukemia, prostate, and breast cancer cells

Abstract

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‐α‐tocopherol (vitamin E) on a series of well‐established cancer cell lines that included two erythroleukemia cell lines and a hormone‐responsive breast and prostate cancer cell line. Cell proliferation was examined in these cell lines, which were maintained at optimal growth conditions. A dose‐dependent inhibition of cell growth was found in all cell lines examined, with the MCF‐7 breast and CRL‐1740 prostate cancer cell lines showing potent suppression of growth at 0.1 mM vitamin E, whereas the erythroleukemia cell lines, HEL and OCIM‐1, responded only at >0.25 mM vitamin E with inhibition of proliferation. Studies of [³H]thymidine incorporation showed that vitamin E supplementation reduced DNA synthesis in all cell lines. Analysis of high‐molecular‐weight DNA revealed extensive fragmentation, indicating apoptosis of all cell lines supplemented with vitamin E. Our studies thus give evidence of a general inhibition of cell proliferation by dl‐α‐tocopherol, with breast and prostate cancer cells distinctly more sensitive than erythroleukemia cells.