PTH1-34 blocks radiation-induced osteoblast apoptosis by enhancing DNA repair through canonical Wnt pathway

Abhishek Chandra, Tiao Lin, Ji Zhu, Wei Tong, Yanying Huo, Haoruo Jia, Yejia Zhang, X. Sherry Liu, Keith Cengel, Bing Xia, Ling Qin

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

Focal radiotherapy for cancer patients has detrimental effects on bones within the radiation field and the primary clinical signs of bone damage include the loss of functional osteoblasts. We reported previously that daily injection of parathyroid hormone (PTH, 1-34) alleviates radiation-induced osteopenia in a preclinical radiotherapy model by improving osteoblast survival. To elucidate the molecular mechanisms, we irradiated osteoblastic UMR 106-01 cells and calvarial organ culture and demonstrated an anti-apoptosis effect of PTH1-34 on these cultures. Inhibitor assay indicated that PTH exerts its radioprotective action mainly through protein kinase A/β-catenin pathway. γ-H2AX foci staining and comet assay revealed that PTH efficiently promotes the repair of DNA double strand breaks (DSBs) in irradiated osteoblasts via activating the β-catenin pathway. Interestingly, Wnt3a alone also blocked cell death and accelerated DNA repair in primary osteoprogenitors, osteoblastic and osteocytic cells after radiation through the canonical signaling. Further investigations revealed that both Wnt3a andPTHincrease the amount of Ku70, a core protein for initiating the assembly of DSB repair machinery, in osteoblasts after radiation. Moreover, down-regulation of Ku70 by siRNA abrogated the prosurvival effect of PTH and Wnt3a on irradiated osteoblasts. In summary, our results identify a novel role of PTH and canonical Wnt signaling in regulating DSB repair machinery and apoptosis in osteoblasts and shed light on using PTH1-34 or Wnt agonist as possible therapy for radiation-induced osteoporosis.

Original languageEnglish (US)
Pages (from-to)157-167
Number of pages11
JournalJournal of Biological Chemistry
Volume290
Issue number1
DOIs
StatePublished - Jan 2 2015
Externally publishedYes

    Fingerprint

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Chandra, A., Lin, T., Zhu, J., Tong, W., Huo, Y., Jia, H., Zhang, Y., Liu, X. S., Cengel, K., Xia, B., & Qin, L. (2015). PTH1-34 blocks radiation-induced osteoblast apoptosis by enhancing DNA repair through canonical Wnt pathway. Journal of Biological Chemistry, 290(1), 157-167. https://doi.org/10.1074/jbc.M114.608158