title: Bone morphogenetic protein 6 (BMP6) and BMP7 inhibit estrogen-induced proliferation of breast cancer cells by suppressing p38 mitogen-activated protein kinase activation.
abstract: Estrogen is involved in the development and progression of breast cancer. Here, we investigated the effects of bone morphogenetic proteins (BMPs) on breast cancer cell proliferation caused by estrogen using human breast cancer MCF-7 cells. MCF-7 cells express estrogen receptors (ESR1 and ESR2), BMP receptors, and SMAD signaling molecules. Estradiol and membrane-impermeable estradiol stimulated MCF-7 cell proliferation. Estradiol also reduced mRNA levels of ESR1, aromatase, and steroid sulfatase. Treatment with BMPs and activin had no effects on MCF-7 cell proliferation. However, BMP2, BMP4, BMP6, BMP7, and activin suppressed estradiol-induced cell mitosis, with the effects of BMP6, BMP7, and activin being more prominent than those of BMP2 and BMP4. Activin decreased ESR1 mRNA expression, while BMP6 and BMP7 impaired steroid sulfatase expression in MCF-7 cells. Interestingly, SMAD1,5,8 activation elicited by BMP6 and BMP7, but not by BMP2 and BMP4, was preserved even under the exposure of a high concentration of estradiol. The difference of BMP responsiveness was likely due to the differential modulation of BMP receptor expression induced by estradiol. In this regard, estradiol decreased the expression levels of BMPR1A, BMPR1B, ACVR2A, and ACVR2B but did not affect ACVR1 and BMPRII, leading to the sustained effects of BMP6 and BMP7 in estrogen-treated MCF-7 cells. Estradiol rapidly activated MAPK phosphorylation including extracellular signal-regulated kinase 1/2, p38, and stress-activated protein kinase/c-Jun NH2-terminal kinase pathways and BMP6, BMP7, and activin preferentially inhibited estradiol-induced p38 phosphorylation. SB203580, a selective p38 MAPK inhibitor effectively suppressed estradiol-induced cell mitosis, suggesting that p38 MAPK plays a key role in estrogen-sensitive breast cancer cell proliferation. Thus, a novel interrelationship between estrogen and the breast cancer BMP system was uncovered, in which inhibitory effects of BMP6 and BMP7 on p38 signaling and steroid sulfatase expression were functionally involved in the suppression of estrogen-induced mitosis of breast cancer cells.
authors.affiliation: Department of Cancer and Thoracic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama City 700-8558, Japan.
authors.forename: Mina
authors.initials: M
authors.lastname: Takahashi
authors.forename: Fumio
authors.initials: F
authors.lastname: Otsuka
authors.forename: Tomoko
authors.initials: T
authors.lastname: Miyoshi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Otani
authors.forename: Junko
authors.initials: J
authors.lastname: Goto
authors.forename: Misuzu
authors.initials: M
authors.lastname: Yamashita
authors.forename: Toshio
authors.initials: T
authors.lastname: Ogura
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Makino
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Doihara
mesh_terms: D028341:Activins / Q000494:pharmacology; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology; D055415:Bone Morphogenetic Protein 4 / Q000494:pharmacology; D055418:Bone Morphogenetic Protein 6 / Q000494:pharmacology*; D055419:Bone Morphogenetic Protein 7 / Q000494:pharmacology*; D052005:Bone Morphogenetic Protein Receptors, Type I / Q000235:genetics; D052006:Bone Morphogenetic Protein Receptors, Type II / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects*; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000235:genetics; D047629:Estrogen Receptor beta / Q000235:genetics; D004967:Estrogens / Q000494:pharmacology; D038681:Follistatin / Q000235:genetics; D006801:Humans; D008856:Microscopy, Fluorescence; D008938:Mitosis / Q000187:drug effects; D020411:Oligonucleotide Array Sequence Analysis; D011960:Receptors, Estrogen / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D043266:Steryl-Sulfatase / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: C525718:BMP2 protein, human; C525809:BMP4 protein, human; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D055418:Bone Morphogenetic Protein 6; D055419:Bone Morphogenetic Protein 7; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens; D038681:Follistatin; D011960:Receptors, Estrogen; C422405:activin A; D028341:Activins; D004958:Estradiol; D048051:p38 Mitogen-Activated Protein Kinases; D052005:Bone Morphogenetic Protein Receptors, Type I; D052006:Bone Morphogenetic Protein Receptors, Type II; D043266:Steryl-Sulfatase