title: TAT-mediated delivery of Tousled protein to salivary glands protects against radiation-induced hypofunction.
abstract: OBJECTIVE
  Patients treated with radiotherapy for head-and-neck cancer invariably suffer its deleterious side effect, xerostomia. Salivary hypofunction ensuing from the irreversible destruction of glands is the most common and debilitating oral complication affecting patients undergoing regional radiotherapy. Given that the current management of xerostomia is palliative and ineffective, efforts are now directed toward preventive measures to preserve gland function. The human homolog of Tousled protein, TLK1B, facilitates chromatin remodeling at DNA repair sites and improves cell survival against ionizing radiation (IR). Therefore, we wanted to determine whether a direct transfer of TLK1B protein to rat salivary glands could protect against IR-induced salivary hypofunction.
  
  
  METHODS
  The cell-permeable TAT-TLK1B fusion protein was generated. Rat acinar cell line and rat salivary glands were pretreated with TAT peptide or TAT-TLK1B before IR. The acinar cell survival in vitro and salivary function in vivo were assessed after radiation.
  
  
  RESULTS
  We demonstrated that rat acinar cells transduced with TAT-TLK1B were more resistant to radiation (D₀ = 4.13 ± 1.0 Gy; α/β = 0 Gy) compared with cells transduced with the TAT peptide (D₀ = 4.91 ± 1.0 Gy; α/β = 20.2 Gy). Correspondingly, retroductal instillation of TAT-TLK1B in rat submandibular glands better preserved salivary flow after IR (89%) compared with animals pretreated with Opti-MEM or TAT peptide (31% and 39%, respectively; p < 0.01).
  
  
  CONCLUSIONS
  The results demonstrate that a direct transfer of TLK1B protein to the salivary glands effectively attenuates radiation-mediated gland dysfunction. Prophylactic TLK1B-protein therapy could benefit patients undergoing radiotherapy for head-and-neck cancer.
authors.affiliation: Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA. gsunav@lsuhsc.edu
authors.forename: Gulshan
authors.initials: G
authors.lastname: Sunavala-Dossabhoy
authors.forename: Senthilnathan
authors.initials: S
authors.lastname: Palaniyandi
authors.forename: Charles
authors.initials: C
authors.lastname: Richardson
authors.forename: Arrigo
authors.initials: A
authors.lastname: De Benedetti
authors.forename: Lisa
authors.initials: L
authors.lastname: Schrott
authors.forename: Gloria
authors.initials: G
authors.lastname: Caldito
mesh_terms: D061354:Acinar Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects* / Q000528:radiation effects; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D008156:Luciferases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000008:administration & dosage* / Q000302:isolation & purification / Q000378:metabolism; D011836:Radiation Tolerance / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage* / Q000302:isolation & purification / Q000378:metabolism; D012469:Salivary Glands / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D012472:Salivation / Q000187:drug effects / Q000528:radiation effects; D013363:Submandibular Gland / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D014987:Xerostomia / Q000517:prevention & control*; D001616:beta-Galactosidase / Q000378:metabolism; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000008:administration & dosage* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D011993:Recombinant Fusion Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; D008156:Luciferases; D017346:Protein Serine-Threonine Kinases; C425323:TLK1 protein, human; D001616:beta-Galactosidase