title: microRNA alterations driving acute and late stages of radiation-induced fibrosis in a murine skin model.
abstract: OBJECTIVE
  Although ionizing radiation is critical in treating cancer, radiation-induced fibrosis (RIF) can have a devastating impact on patients' quality of life. The molecular changes leading to radiation-induced fibrosis must be elucidated so that novel treatments can be designed.
  
  
  METHODS
  To determine whether microRNAs (miRs) could be responsible for RIF, the fibrotic process was induced in the right hind legs of 9-week old CH3 mice by a single-fraction dose of irradiation to 35 Gy, and the left leg served as an unirradiated control. Fibrosis was quantified by measurements of leg length compared with control leg length. By 120 days after irradiation, the irradiated legs were 20% (P=.013) shorter on average than were the control legs.
  
  
  RESULTS
  Tissue analysis was done on muscle, skin, and subcutaneous tissue from irradiated and control legs. Fibrosis was noted on both gross and histologic examination by use of a pentachrome stain. Microarrays were performed at various times after irradiation, including 7 days, 14 days, 50 days, 90 days, and 120 days after irradiation. miR-15a, miR-21, miR-30a, and miR-34a were the miRs with the most significant alteration by array with miR-34a, proving most significant on confirmation by reverse transcriptase polymerase chain reaction, c-Met, a known effector of fibrosis and downstream molecule of miR-34a, was evaluated by use of 2 cell lines: HCT116 and 1522. The cell lines were exposed to various stressors to induce miR changes, specifically ionizing radiation. Additionally, in vitro transfections with pre-miRs and anti-miRs confirmed the relationship of miR-34a and c-Met.
  
  
  CONCLUSIONS
  Our data demonstrate an inverse relationship with miR-34a and c-Met; the upregulation of miR-34a in RIF causes inhibition of c-Met production. miRs may play a role in RIF; in particular, miR-34a should be investigated as a potential target to prevent or treat this devastating side effect of irradiation.
authors.affiliation: Department of Radiation Oncology, Kimmel Cancer Center, Jefferson Medical College of Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
authors.forename: Brittany A
authors.initials: BA
authors.lastname: Simone
authors.affiliation: Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: David
authors.initials: D
authors.lastname: Ly
authors.affiliation: Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Jason E
authors.initials: JE
authors.lastname: Savage
authors.affiliation: Department of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Hewitt
authors.affiliation: Department of Radiation Oncology, Kimmel Cancer Center, Jefferson Medical College of Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
authors.forename: Tu D
authors.initials: TD
authors.lastname: Dan
authors.affiliation: Department of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Kris
authors.initials: K
authors.lastname: Ylaya
authors.affiliation: Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Uma
authors.initials: U
authors.lastname: Shankavaram
authors.affiliation: Department of Radiation Oncology, Kimmel Cancer Center, Jefferson Medical College of Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
authors.forename: Meng
authors.initials: M
authors.lastname: Lim
authors.affiliation: Department of Radiation Oncology, Kimmel Cancer Center, Jefferson Medical College of Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
authors.forename: Lianjin
authors.initials: L
authors.lastname: Jin
authors.affiliation: Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Kevin
authors.initials: K
authors.lastname: Camphausen
authors.affiliation: Radiation Biology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: James B
authors.initials: JB
authors.lastname: Mitchell
authors.affiliation: Department of Radiation Oncology, Kimmel Cancer Center, Jefferson Medical College of Thomas Jefferson University Hospital, Philadelphia, Pennsylvania. Electronic address: nicole.simone@jeffersonhospital.org.
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Simone
mesh_terms: D000818:Animals; D005355:Fibrosis; D007870:Leg Length Inequality / Q000209:etiology* / Q000473:pathology; D051379:Mice; D008809:Mice, Inbred C3H; D035683:MicroRNAs / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D011833:Radiation Injuries, Experimental / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012867:Skin / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D040521:Subcutaneous Tissue / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects
chemical_list: C531950:MIRN21 microRNA, mouse; C551848:MIRN34a microRNA, mouse; D035683:MicroRNAs; C544301:Mirn15a microRNA, mouse; C534715:Mirn30d microRNA, mouse; D019859:Proto-Oncogene Proteins c-met