title: Comparative effects of sesame seed lignan and flaxseed lignan in reducing the growth of human breast tumors (MCF-7) at high levels of circulating estrogen in athymic mice.
abstract: Flaxseed (FS) has a breast tumor-reducing effect, possibly because of its high content of secoisolariciresinol diglucoside (SDG) lignan. Sesame seed (SS) is rich in the lignan sesamin (SES) but is non-protective. Both lignans are metabolized to estrogen-like enterodiol and enterolactone. The objective of this study was to differentiate the effects of SDG and SES on established human estrogen receptor-positive breast tumors (MCF-7) in athymic mice with high serum estrogen to help explain the different effects of FS and SS. Mice were fed for 8 wk the basal diet (BD, control) or BD supplemented with 1 g/kg SDG or SES. SES reduced palpable tumor size by 23% compared to control, whereas SDG did not differ from SES or control. Both treatments reduced tumor cell proliferation, but only SES increased apoptosis. SDG and SES reduced human epidermal growth factor receptor 2 and endothelial growth factor receptor expressions, but only SES reduced downstream pMAPK. Neither treatment affected IGF-1R, vascular endothelial growth factor receptor-2, Akt, pAkt, or MAPK of the growth factor signaling pathway. Thus, at high serum estrogen levels, SDG may not account for the tumor reducing effect of FS. SES was more effective than SDG in reducing breast tumor growth, but its effect may have been lost when consumed as a component of SS.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Truan
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Chen
authors.forename: Lilian U
authors.initials: LU
authors.lastname: Thompson
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D002072:Butylene Glycols / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004149:Dioxoles / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects; D004967:Estrogens / Q000097:blood; D005260:Female; D019597:Flax / Q000737:chemistry*; D005960:Glucosides / Q000494:pharmacology*; D006801:Humans; D017705:Lignans / Q000494:pharmacology*; D051379:Mice; D008819:Mice, Nude; D018719:Erb-b2 Receptor Tyrosine Kinases; D017526:Receptor, IGF Type 1; D011960:Receptors, Estrogen / Q000378:metabolism; D012639:Seeds / Q000737:chemistry; D031685:Sesamum / Q000737:chemistry*; D015398:Signal Transduction; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D002072:Butylene Glycols; D004149:Dioxoles; D004967:Estrogens; D005960:Glucosides; D017705:Lignans; D018719:Erb-b2 Receptor Tyrosine Kinases; D017526:Receptor, IGF Type 1; D011960:Receptors, Estrogen; D040301:Vascular Endothelial Growth Factor Receptor-2; C508053:ERBB2 protein, human; C054125:sesamin; C090142:secoisolariciresinol diglucoside