title: Transient activation of hedgehog pathway rescued irradiation-induced hyposalivation by preserving salivary stem/progenitor cells and parasympathetic innervation.
abstract: OBJECTIVE
  To examine the effects and mechanisms of transient activation of the Hedgehog pathway on rescuing radiotherapy-induced hyposalivation in survivors of head and neck cancer.
  
  
  METHODS
  Mouse salivary glands and cultured human salivary epithelial cells were irradiated by a single 15-Gy dose. The Hedgehog pathway was transiently activated in mouse salivary glands, by briefly overexpressing the Sonic hedgehog (Shh) transgene or administrating smoothened agonist, and in human salivary epithelial cells, by infecting with adenovirus encoding Gli1. The activity of Hedgehog signaling was examined by the expression of the Ptch1-lacZ reporter and endogenous Hedgehog target genes. The salivary flow rate was measured following pilocarpine stimulation. Salivary stem/progenitor cells (SSPC), parasympathetic innervation, and expression of related genes were examined by flow cytometry, salisphere assay, immunohistochemistry, quantitative reverse transcription PCR, Western blotting, and ELISA.
  
  
  RESULTS
  Irradiation does not activate Hedgehog signaling in mouse salivary glands. Transient Shh overexpression activated the Hedgehog pathway in ductal epithelia and, after irradiation, rescued salivary function in male mice, which is related with preservation of functional SSPCs and parasympathetic innervation. The preservation of SSPCs was likely mediated by the rescue of signaling activities of the Bmi1 and Chrm1-HB-EGF pathways. The preservation of parasympathetic innervation was associated with the rescue of the expression of neurotrophic factors such as Bdnf and Nrtn. The expression of genes related with maintenance of SSPCs and parasympathetic innervation in female salivary glands and cultured human salivary epithelial cells was similarly affected by irradiation and transient Hedgehog activation.
  
  
  CONCLUSIONS
  These findings suggest that transient activation of the Hedgehog pathway has the potential to restore salivary gland function after irradiation-induced dysfunction.
authors.affiliation: Institute for Regenerative Medicine at Scott & White, Molecular and Cellular Medicine Department, Texas A&M Health Science Center, Temple, Texas 76502, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Hai
authors.affiliation: Institute for Regenerative Medicine at Scott & White, Molecular and Cellular Medicine Department, Texas A&M Health Science Center, Temple, Texas 76502, USA.|Beijing Stomatological Hospital, Capital Medical University, Beijing 100050, China.
authors.forename: Lizheng
authors.initials: L
authors.lastname: Qin
authors.affiliation: Institute for Regenerative Medicine at Scott & White, Molecular and Cellular Medicine Department, Texas A&M Health Science Center, Temple, Texas 76502, USA.|Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Institute for Regenerative Medicine at Scott & White, Molecular and Cellular Medicine Department, Texas A&M Health Science Center, Temple, Texas 76502, USA.
authors.forename: Qingguo
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: Institute for Regenerative Medicine at Scott & White, Molecular and Cellular Medicine Department, Texas A&M Health Science Center, Temple, Texas 76502, USA.|Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Shangguan
authors.affiliation: Institute for Regenerative Medicine at Scott & White, Molecular and Cellular Medicine Department, Texas A&M Health Science Center, Temple, Texas 76502, USA.|Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Ti
authors.affiliation: Institute for Regenerative Medicine at Scott & White, Molecular and Cellular Medicine Department, Texas A&M Health Science Center, Temple, Texas 76502, USA.|Lutheran Medical Center, Brooklyn, NY 11220, USA.
authors.forename: Yanqiu
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Radiation Oncology, Scott and White Hospital, Temple, Texas 76502, USA.
authors.forename: Sangroh
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, Scott and White Hospital, Temple, Texas 76502, USA.
authors.forename: Dharanipathy
authors.initials: D
authors.lastname: Rangaraj
authors.affiliation: Institute for Regenerative Medicine at Scott & White, Molecular and Cellular Medicine Department, Texas A&M Health Science Center, Temple, Texas 76502, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
mesh_terms: D000328:Adult; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy; D005260:Female; D015870:Gene Expression / Q000528:radiation effects; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D053823:Hedgehog Proteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D009414:Nerve Growth Factors / Q000378:metabolism; D010275:Parasympathetic Nervous System / Q000503:physiopathology* / Q000528:radiation effects; D011833:Radiation Injuries, Experimental / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D015398:Signal Transduction; D013234:Stem Cells / Q000378:metabolism* / Q000528:radiation effects; D013363:Submandibular Gland / Q000294:innervation / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D014987:Xerostomia / Q000378:metabolism*
chemical_list: D053823:Hedgehog Proteins; D009414:Nerve Growth Factors; C465570:Shh protein, mouse