RRR‐α‐Tocopheryl succinate inhibits proliferation and enhances secretion of transforming growth factor‐β (TGF‐β) by human breast cancer cells

Abstract

The RRR‐α‐tocopheryl succinate form of vitamin E inhibits the proliferation of estrogen receptor‐positive and estrogen receptor‐negative human breast cancer cell lines in a dose‐dependent manner in vitro. Analyses of cell‐conditioned medium from RRR‐α‐tocopheryl succinate growth‐inhibited cells revealed the presence of a potent antiproliferative activity. Characterization of the antiproliferative activity as transforming growth factor‐β (TGF‐β) was established by 1) growth inhibition of the TGF‐β‐responsive Mv1Lu‐CCL‐64 mink lung and murine CTLL‐2 cell lines, 2) combination of physical characteristics including heat stability, acid stability, and Bio‐Gel P‐60 column chromatography elution profile, and 3) neutralization of the antiproliferative activity in the conditioned media by antibodies specific for TGF‐β.