title: PTHrP(12-48) Modulates the Bone Marrow Microenvironment and Suppresses Human Osteoclast Differentiation and Lifespan.
abstract: Bone is a common site for metastasis in breast cancer patients and is associated with a series of complications that significantly compromise patient survival, partially due to the advanced stage of disease at the time of detection. Currently, no clinically-approved biomarkers can identify or predict the development of bone metastasis. We recently identified a unique peptide fragment of parathyroid hormone-related protein (PTHrP), PTHrP(12-48), as a validated serum biomarker in breast cancer patients that correlates with and predicts the presence of bone metastases. In this study, the biological activity and mode of action of PTHrP(12-48) was investigated. Sequence-based and structure-based bioinformatics techniques predicted that the PTHrP(12-48) fragment formed an alpha helical core followed by an unstructured region after residue 40 or 42. Thereafter, detailed structure alignment and molecular docking simulations predicted a lack of interaction between PTHrP(12-48) and the cognate PTH1 receptor (PTHR1). The in silico prediction was confirmed by the lack of PTHrP(12-48)-stimulated cAMP accumulation in PTHR1-expressing human SaOS2 cells. Using a specific human PTHrP(12-48) antibody that we developed, PTHrP(12-48) was immunolocalized in primary and bone metastatic human breast cancer cells, as well as within human osteoclasts (OCLs) in bone metastasis biopsies, with little or no localization in other resident bone or bone marrow cells. In vitro, PTHrP(12-48) was internalized into cultured primary human OCLs and their precursors within 60 min. Interestingly, PTHrP(12-48) treatment dose-dependently suppressed osteoclastogenesis, via the induction of apoptosis in both OCL precursors as well as in mature OCLs, as measured by the activation of cleaved caspase 3. Collectively, these data suggest that PTHrP(12-48) is a bioactive breast cancer-derived peptide that locally regulates the differentiation of hematopoietic cells and the activity of osteoclasts within the tumor-bone marrow microenvironment, perhaps to facilitate tumor control of bone. © 2017 American Society for Bone and Mineral Research.
authors.affiliation: Department of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, USA.
authors.forename: Archana
authors.initials: A
authors.lastname: Kamalakar
authors.affiliation: Department of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, USA.
authors.forename: Charity L
authors.initials: CL
authors.lastname: Washam
authors.affiliation: Department of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, USA.
authors.forename: Nisreen S
authors.initials: NS
authors.lastname: Akel
authors.affiliation: Department of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, USA.
authors.forename: Bethany J
authors.initials: BJ
authors.lastname: Allen
authors.affiliation: Department of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, USA.|Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
authors.forename: Diarra K
authors.initials: DK
authors.lastname: Williams
authors.affiliation: Department of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, USA.
authors.forename: Frances L
authors.initials: FL
authors.lastname: Swain
authors.affiliation: Department of Medicine, Penn State University, Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Kim
authors.initials: K
authors.lastname: Leitzel
authors.affiliation: Department of Medicine, Penn State University, Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Allan
authors.initials: A
authors.lastname: Lipton
authors.affiliation: Department of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, USA.|Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
authors.forename: Dana
authors.initials: D
authors.lastname: Gaddy
authors.affiliation: Department of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, USA.|Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
authors.forename: Larry J
authors.identifier: http://orcid.org/0000-0002-2892-9757
authors.initials: LJ
authors.lastname: Suva
mesh_terms: D001859:Bone Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000556:secondary; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002470:Cell Survival; D060833:Cellular Microenvironment; D005260:Female; D000089703:Fibroblast Growth Factor-23; D006801:Humans; D009362:Neoplasm Metastasis; D010010:Osteoclasts / Q000378:metabolism* / Q000473:pathology; D044162:Parathyroid Hormone-Related Protein / Q000378:metabolism*
chemical_list: C000717427:FGF23 protein, human; D044162:Parathyroid Hormone-Related Protein; D000089703:Fibroblast Growth Factor-23
keywords: CELL/TISSUE SIGNALING; ENDOCRINE PATHWAYS; OSTEOCLASTS; PTH/VIT D/FGF23; TUMOR-INDUCED BONE DISEASE