title: Downregulation of tumorogenicity and changes in the actin cytoskeleton of murine hepatoma after irradiation with polychromatic visible and IR light.
abstract: OBJECTIVE
  This study evaluated the function and structural consequences of direct exposure of murine hepatoma MH-22a cells to polychromatic polarized light, to determine potential risk of malignancy following irradiation.
  
  
  BACKGROUND
  Visible (VIS) and infrared (IR) light have been actively used for prevention and treatment of complications developed after conventional tumor therapy. However, the safety associated with this irradiation has not been determined.
  
  
  METHODS
  Polychromatic light (480-3400 and 385-750 nm), were used at different doses (4.8-38.4 J/cm(2)) to determine the viability, proliferation, and actin cytoskeleton in vitro by flow cytometry and confocal microscopy. Tumorogenic properties of cells were studied in vivo after transplantation in C3HA mice.
  
  
  RESULTS
  Polychromatic light of a wide range of doses did not change the viability and proliferation of cells. After transplantation of cells irradiated with VIS-IR light (4.8 and 9.6 J/cm(2)) and VIS light (38.4 J/cm(2)) the tumor volume was lower in the treated group than in the control group in vivo. Transplantability of the irradiated cells also decreased, whereas survival of tumor-bearing mice increased. Three cell populations with different cytoskeleton structure were identified. After irradiation, the reorganized part of the actin cytoskeleton changed its localization to the submembranous area.
  
  
  CONCLUSIONS
  A decrease of tumorigenicity in cells irradiated with polychromatic light used in non-damaging doses correlated with an increase in the number of cells with reorganized actin in the submembranous area. The results of the present study argue in favor of the oncological safety of polychromatic VIS-IR light (480-3400 nm).
authors: 1 Nanotechnology Research and Education Centre , Russian Academy of Sciences, Saint-Petersburg, Russia .
authors: Nickolay A
authors: NA
authors: Knyazev
authors: Kira A
authors: KA
authors: Samoilova
authors: Heidi
authors: H
authors: Abrahamse
authors: Natalia A
authors: NA
authors: Filatova
mesh_terms: D008841:Actin Cytoskeleton / Q000528:radiation effects*; D000818:Animals; D063646:Carcinogenesis / Q000528:radiation effects*; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D018929:Cell Culture Techniques; D049109:Cell Proliferation / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D007259:Infrared Rays; D008113:Liver Neoplasms / Q000473:pathology*; D051379:Mice; D008809:Mice, Inbred C3H; D014407:Tumor Cells, Cultured