Yu W, Heim K, Qian M, Simmons-Menchaca M, Sanders BG, Kline K. Evidence for role of transforming growth factor-beta in RRR-alpha-tocopheryl succinate-induced apoptosis of human MDA-MB-435 breast cancer cells.
Nutr Cancer 1997;
27:267-78. [PMID:
9101557 DOI:
10.1080/01635589709514537]
[Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
MDA-MB-435 human breast cancer cells treated with 10 micrograms/ml of RRR-alpha-tocopheryl succinate (vitamin E succinate, VES) for one, two, three, and four days exhibit 9%, 19%, 51%, and 73% apoptotic cells, respectively. Likewise, cells cultured for one, two, and three days with conditioned media (CM) obtained from MDA-MB-435 cells treated with VES exhibit 10%, 36%, and 74% apoptosis, respectively. A quantitative luciferase-based assay showed CM from VES-treated cells collected at 24 and 48 hours after treatment initiation to contain 75 and 32 pg of active transforming growth factor-beta (TGF-beta), respectively, per 10(6) cells. Although purified TGF-beta 1 is not an effective apoptotic agent for MDA-MD-435 cells, cotreatment of the cells for three days with suboptimal levels of VES (2.5 and 5 micrograms/ml) + 10 ng/ml of purified TGF-beta 1 enhanced apoptosis by 66% and 68%, respectively. Interference of the TGF-beta-signaling pathway by transient transfection of MDA-MB-435 cells with antisense oligomers to TGF-beta type II receptor (TGF-beta R-II) blocked VES-induced apoptosis. Likewise, addition of neutralizing antibodies to TGF-beta 1 or to all three mammalian isoforms of TGF-beta (TGF-beta 1, -beta 2, -beta 3) blocked VES- and CM-induced apoptosis. Furthermore, inhibitors of TGF-beta conversion from an inactive latent form to a biologically active form inhibited VES-induced apoptosis. In summary, the ability to reduce apoptosis by blocking TGF-beta or the TGF-beta receptor-signaling pathway with antisense oligomers or ligand-neutralizing antibodies or prevention of activation of TGF-beta indicates a role for TGF-beta signaling in VES-induced apoptosis.
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