title: LC, a novel estrone-rhein hybrid compound, promotes proliferation and differentiation and protects against cell death in human osteoblastic MG-63 cells.
abstract: Estrogen analogs are promising drugs for postmenopausal osteoporosis, but because of their possible side effects, estrogens which exert their estrogenic effects selectively on bone are desired. Based on our previous studies that rhein had high affinity for the bone mineral, we synthesized estrone-rhein hybrid compounds and confirmed that one of these hybrid compounds, LC, exhibited a selective profile in the bone and prevented bone loss but had no effect on endometrium growth in ovariectomized rats. However, the mechanisms underlying its actions on human bone cells have remained largely unknown. Here we show that LC increases proliferation and differentiation and opposes cisplatin-induced apoptosis in human osteoblastic MG-63 cells containing two estrogen receptor (ER) isoforms. LC promotes proliferation by altering cell cycle distribution whereas LC-mediated survival may be associated with up-regulation of X-linked inhibitor of apoptosis (XIAP) expression. Treatment with the ER antagonist ICI 182,780 abolishes the above actions of LC on osteoblast-derived cells. Using small interfering double-stranded RNAs technology, we further demonstrate that the effects of LC on proliferation and survival are mediated by both ERα and ERβ but those on differentiation primarily by ERα. Moreover, we demonstrate that LC may promote activation of the classic estrogen response element (ERE) pathway through increasing steroid receptor coactivator (SRC)-3 expression. Meanwhile, we find that regulation of osteoblastic proliferation and survival by LC involves Ras/MEK/ERK and PI3K/Akt signaling. Therefore, using rhein for conjugating compounds is a promising method of effectively targeting estrogens to the bone.
authors.affiliation: Department of Immunology, Medical College of Chinese People's Armed Police Forces, Tianjin, People's Republic of China. wy68wy68@yahoo.com.cn
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
authors.forename: Ling Zhi
authors.initials: LZ
authors.lastname: Li
authors.forename: Yong Liang
authors.initials: YL
authors.lastname: Zhang
authors.forename: Wei Jia
authors.initials: WJ
authors.lastname: Sun
authors.forename: Ya Qin
authors.initials: YQ
authors.lastname: Zhu
authors.forename: Ying
authors.initials: Y
authors.lastname: Cui
authors.forename: Lin
authors.initials: L
authors.lastname: Qi
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000880:Anthraquinones / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival; D002945:Cisplatin; D003094:Collagen / Q000378:metabolism; D057075:Enzyme Assays; D004967:Estrogens / Q000494:pharmacology*; D004970:Estrone / Q000031:analogs & derivatives* / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D056921:Nuclear Receptor Coactivator 3 / Q000235:genetics / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects* / Q000502:physiology; D011960:Receptors, Estrogen / Q000819:agonists / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D000880:Anthraquinones; D051017:Apoptosis Regulatory Proteins; D004967:Estrogens; D011960:Receptors, Estrogen; D004970:Estrone; D003094:Collagen; C538866:NCOA3 protein, human; D056921:Nuclear Receptor Coactivator 3; D000469:Alkaline Phosphatase; D002945:Cisplatin; C020491:rhein