Effect of tocotrienols on the growth of a human breast cancer cell line in culture.
The tocotrienol-rich fraction (TRF) of palm oil consists of tocotrienols and some alpha-tocopherol (alpha-T). Tocotrienols are a form of vitamin E having an unsaturated side-chain, rather than the saturated side-chain of the more common tocopherols. Because palm oil has been shown not to promote chemically-induced mammary carcinogenesis, we tested effects of TRF and alpha-T on the proliferation, growth, and plating efficiency (PE) of the MDA-MB-435 estrogen-receptor-negative human breast cancer cells. TRF inhibited the proliferation of these cells with a concentration required to inhibit cell proliferation by 50% of 180 microgram/mL whereas alpha-T had no effect at concentrations up to 1000 microgram/mL as measured by incorporation of [3H]thymidine. The effects of TRF and alpha-T also were tested in longer-term growth experiments, using concentrations of 180 and 500 microgram/mL. We found that TRF inhibited the growth of these cells by 50%, whereas alpha-T did not. Their effect on the ability of these cells to form colonies also was studied, and it was found that TRF inhibited PE, whereas alpha T had no effect. These results suggest that the inhibition is due to the presence of tocotrienols in TRF rather than alpha T.
Nesaretnam
K
K
Palm Oil Research Institute of Malaysia, Kuala Lumpur, Malaysia.
Guthrie
N
N
Chambers
A F
AF
Carroll
K K
KK
D000975:Antioxidants / Q000494:pharmacology; D001943:Breast Neoplasms / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects*; D006801:Humans; D000073878:Palm Oil; D010938:Plant Oils / Q000737:chemistry; D014407:Tumor Cells, Cultured; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000494:pharmacology
D000975:Antioxidants; D010938:Plant Oils; D014810:Vitamin E; D000073878:Palm Oil