title: Nanoparticle-mediated gene silencing confers radioprotection to salivary glands in vivo.
abstract: Radiation treatment of head and neck cancers causes irreversible damage of the salivary glands (SG). Here, we introduce a preclinical mouse model for small-interfering RNA (siRNA)-based gene silencing to provide protection of SG from radiation-induced apoptosis. Novel, pH-responsive nanoparticles complexed with siRNAs were introduced into mouse submandibular glands (SMG) by retroductal injection to modulate gene expression in vivo. To validate this approach, we first targeted Nkcc1, an ion transporter that is essential for saliva secretion. Nkcc1 siRNA delivery resulted in efficient knockdown, as quantified at the mRNA and the protein levels, and the functional result of Nkcc1 knockdown phenocopied the severe decrease in saliva secretion, characteristic of the systemic Nkcc1 gene knockout. To establish a strategy to prevent apoptotic cell loss due to radiation damage, siRNAs targeting the proapoptotic Pkcδ gene were administered into SMG before ionizing radiation. Knockdown of Pkcδ not only reduced the number of apoptotic cells during the acute phase of radiation damage, but also markedly improved saliva secretion at 3 months in irradiated animals, indicating that this treatment confers protection from hyposalivation. These results demonstrate that nanoparticle delivery of siRNAs targeting a proapoptotic gene is a localized, nonviral, and effective means of conferring radioprotection to the SGs.
authors.affiliation: Center for Oral Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
authors.forename: Szilvia
authors.initials: S
authors.lastname: Arany
authors.forename: Danielle S W
authors.initials: DS
authors.lastname: Benoit
authors.forename: Stephen
authors.initials: S
authors.lastname: Dewhurst
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Ovitt
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D005260:Female; D055785:Gene Knockdown Techniques; D020868:Gene Silencing / Q000187:drug effects*; D015316:Genetic Therapy; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry*; D051745:Protein Kinase C-delta / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000235:genetics; D011837:Radiation-Protective Agents / Q000008:administration & dosage / Q000737:chemistry*; D011878:Radiotherapy / Q000009:adverse effects; D012472:Salivation; D064506:Solute Carrier Family 12, Member 2 / Q000235:genetics / Q000378:metabolism; D013363:Submandibular Gland / Q000473:pathology / Q000528:radiation effects*; D014987:Xerostomia / Q000209:etiology / Q000235:genetics / Q000517:prevention & control
chemical_list: D034741:RNA, Small Interfering; D011837:Radiation-Protective Agents; C578878:Slc12a2 protein, mouse; D064506:Solute Carrier Family 12, Member 2; C497259:Prkcd protein, mouse; D051745:Protein Kinase C-delta