title: Chronobiological approaches to antiangiogenic photodynamic therapy of tumors: the first experimental evaluation.
abstract: In research of the last decade, rhythmic (circadian) variations of vascular endothelial growth factor (VEGF) production by tumors were discovered. The present paper authors have earlier synthesized and characterized a new derivative photosensitizer - an immunoconjugate of hematoporphyrin with antiVEGF antibodies.
  
  
  OBJECTIVE
  To elaborate and to test a novel modification of the photodynamic therapy of tumors (PDT) method, founding upon a timed introduction of the immunoconjugated photosensitizer to tumor-bearing animals, so that this coincides with a maximum content of VEGF in tumor tissues.
  
  
  METHODS
  Circadian variations of VEGF contents in murine transplanted tumors, Lewis lung carcinoma and sarcoma 180, were determined by ELISA method. Immunoconjugated photosensitizer concentrations in tumors were estimated by spectrofluorometry. Photoirradiation of the tumors was carried out with a red light (wavelength of 635 nm) from a semiconductor laser. Light doses were chosen, calculating on a partial inhibition of tumor growth, in order that a dependence of PDT efficiency on a daily time-moment (circadian rhythm phase) of the treatment could be observed distinctly.
  
  
  RESULTS
  Circadian variations of the VEGF levels in Lewis lung carcinoma and sarcoma 180 were demonstrated with the maximum at 14:00 h and the minimum at 02:00 h. Intra-abdominal introduction into tumor-bearing mice of the immunoconjugated photosensitizer resulted in a greater accumulation of the immunoconjugate in tumors at 14:00 h than at 02:00 h. Laser irradiation of carcinomas and sarcomas at 14:00 h or 02:00 h after introduction of the immunoconjugated photosensitizer to mice the day before at the same time points, induced a significantly enhanced inhibition of tumor growth in animals treated at day-time versus those treated at night-time.
  
  
  CONCLUSIONS
  The obtained results justify further attempts to transfer principles of tumor chronochemotherapy onto photodynamic therapy.
authors.affiliation: Kavetsky Institute for Experimental Pathology, Oncology and Radiobiology NAS of Ukraine, Kiev 03022, Ukraine. gamaleia@onconet.kiev.ua
authors.forename: N F
authors.initials: NF
authors.lastname: Gamaleia
authors.forename: I A
authors.initials: IA
authors.lastname: Lisnyak
authors.forename: E D
authors.initials: ED
authors.lastname: Shishko
authors.forename: A A
authors.initials: AA
authors.lastname: Mamchur
authors.forename: I V
authors.initials: IV
authors.lastname: Prokopenko
authors.forename: V V
authors.initials: VV
authors.lastname: Kholin
mesh_terms: D020533:Angiogenesis Inhibitors / Q000008:administration & dosage*; D000818:Animals; D018827:Carcinoma, Lewis Lung; D019454:Chronotherapy / Q000379:methods*; D002940:Circadian Rhythm / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D006415:Hematoporphyrins / Q000008:administration & dosage; D008297:Male; D051379:Mice; D009374:Neoplasms, Experimental / Q000098:blood supply / Q000378:metabolism / Q000628:therapy*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
chemical_list: D020533:Angiogenesis Inhibitors; D006415:Hematoporphyrins; D017319:Photosensitizing Agents; D042461:Vascular Endothelial Growth Factor A