title: Silencing of ferrochelatase enhances 5-aminolevulinic acid-based fluorescence and photodynamic therapy efficacy.
abstract: BACKGROUND
  Recurrence of glioma frequently occurs within the marginal area of the surgical cavity due to invading residual cells. 5-Aminolevulinic acid (5-ALA) fluorescence-guided resection has been used as effective therapeutic modalities to improve discrimination of brain tumour margins and patient prognosis. However, the marginal areas of glioma usually show vague fluorescence, which makes tumour identification difficult, and the applicability of 5-ALA-based photodynamic therapy (PDT) is hampered by insufficient therapeutic efficacy in glioma tissues.
  
  
  METHODS
  To overcome these issues, we assessed the expression of ferrochelatase (FECH) gene, which encodes a key enzyme that catalyses the conversion of protoporphyrin IX (PpIX) to heme, in glioma surgical specimens and manipulated FECH in human glioma cell lines.
  
  
  RESULTS
  Prominent downregulation of FECH mRNA expression was found in glioblastoma tissues compared with normal brain tissues, suggesting that FECH is responsible for PpIX accumulation in glioblastoma cells. Depletion of FECH by small interference RNA enhanced PpIX fluorescence after exposure to 5-ALA concomitant with increased intracellular PpIX accumulation in glioma cells. Silencing of FECH caused marked growth inhibition and apoptosis induction by PDT in glioma cells.
  
  
  CONCLUSIONS
  These results suggest that knockdown of FECH is a potential approach to enhance PpIX fluorescent quality for optimising the subjective discrimination of vague fluorescence and improving the effect of 5-ALA-PDT.
authors.affiliation: Department of Neurosurgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa 920-8641, Japan.
authors.forename: L
authors.initials: L
authors.lastname: Teng
authors.forename: M
authors.initials: M
authors.lastname: Nakada
authors.forename: S-G
authors.initials: SG
authors.lastname: Zhao
authors.forename: Y
authors.initials: Y
authors.lastname: Endo
authors.forename: N
authors.initials: N
authors.lastname: Furuyama
authors.forename: E
authors.initials: E
authors.lastname: Nambu
authors.forename: I V
authors.initials: IV
authors.lastname: Pyko
authors.forename: Y
authors.initials: Y
authors.lastname: Hayashi
authors.forename: J-I
authors.initials: JI
authors.lastname: Hamada
mesh_terms: D000622:Aminolevulinic Acid / Q000494:pharmacology*; D045744:Cell Line, Tumor; D005294:Ferrochelatase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005453:Fluorescence; D020868:Gene Silencing; D005910:Glioma / Q000628:therapy*; D006801:Humans; D010778:Photochemotherapy / Q000379:methods*; D011524:Protoporphyrins / Q000378:metabolism*
chemical_list: D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX; D005294:Ferrochelatase