title: Attenuated Wnt/β-catenin signalling mediates methotrexate chemotherapy-induced bone loss and marrow adiposity in rats.
abstract: Cancer chemotherapy often causes significant bone loss, marrow adiposity and haematopoietic defects, yet the underlying mechanisms and recovery potential remain unclear. Wnt/β-catenin signalling is integral to the regulation of osteogenesis, adipogenesis and haematopoiesis; using a rat model, the current study investigated roles of this signalling pathway in changes to bone marrow stromal and haematopoietic cell differentiation after chemotherapy with methotrexate (MTX), a commonly used antimetabolite. MTX treatment in rats (5 daily administrations at 0.75 mg/kg) has previously been found to decrease bone volume and increase marrow fat, which was associated with increased osteoclastogenesis in haematopoietic cells and with an osteogenesis to adipogenesis switch in bone marrow stromal cells of treated rats. In the current study, on day 6 after the first MTX dose we found that accompanying these changes as well as a suppressed haematopoietic cellularity but increased granulocyte/macrophage differentiation potential, there was an increase in mRNA expression of Wnt antagonists sFRP-1 and Dkk-1 in bone, a reduction in nuclear β-catenin protein in bone marrow stromal cells, and decreased mRNA levels of β-catenin target genes lef-1, cyclin D1 and survivin, suggesting reduced activation of Wnt/β-catenin signalling in the bone during MTX-induced damage. Concurrent administration of BIO, a GSK-3β inhibitor that stabilises β-catenin, partially abrogated the MTX-induced transient changes in osteogenic/adipogenic commitment, granulocyte/macrophage lineage differentiation and osteoclast number. These findings demonstrate a potentially important role of Wnt/β-catenin signalling in MTX chemotherapy-induced cellular changes to the bone marrow microenvironment.
authors.affiliation: Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia.
authors.forename: Kristen R
authors.initials: KR
authors.lastname: Georgiou
authors.forename: Tristan J
authors.initials: TJ
authors.lastname: King
authors.forename: Michaela A
authors.initials: MA
authors.lastname: Scherer
authors.forename: Hong
authors.initials: H
authors.lastname: Zhou
authors.forename: Bruce K
authors.initials: BK
authors.lastname: Foster
authors.forename: Cory J
authors.initials: CJ
authors.lastname: Xian
mesh_terms: D050156:Adipogenesis / Q000187:drug effects; D050154:Adiposity / Q000187:drug effects; D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity*; D001853:Bone Marrow / Q000187:drug effects / Q000473:pathology; D001862:Bone Resorption / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D001842:Bone and Bones / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors; D000071679:Glycogen Synthase Kinase 3 beta; D006410:Hematopoiesis / Q000187:drug effects / Q000235:genetics; D008297:Male; D008727:Methotrexate / Q000633:toxicity*; D023421:Models, Animal; D010006:Osteoblasts / Q000187:drug effects / Q000473:pathology; D010010:Osteoclasts / Q000187:drug effects / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D060449:Wnt Signaling Pathway / Q000187:drug effects* / Q000235:genetics; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; C495268:Ctnnb1 protein, rat; D012333:RNA, Messenger; D051176:beta Catenin; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D038362:Glycogen Synthase Kinase 3; D008727:Methotrexate