title: Comparison of expression pattern of monoamine oxidase A with histopathologic subtypes and tumour grade of renal cell carcinoma.
abstract: BACKGROUND
  Studies of the biochemical properties of MAO-A (monoamine oxidase) are numerous, but the information about determination of MAO-A in human normal and tumour renal tissue is limited. Our objectives in the present study were to determine the localization of MAO-A in normal kidney and level of expression of this protein in tumour kidney.
  
  
  METHODS
  Enzyme immunohistochemical method was chosen for detection of MAO-A in 63 clinical samples of all histopathological types of RCC (renal cell carcinoma). Our results were compared to basic clinical and histopathological parameters such as histopathological type and tumour grade. We also compared MAO-A expression between normal and tumour tissue samples.
  
  
  RESULTS
  We confirmed the elevated expression of MAO-A in high-grade tumours of renal cell carcinoma specimens. The percentage of MAO-positive samples progressively increased from 9% in grade 2 to 45% in grade 3. We also noted high levels of MAO-A immunoreactivity in epithelial cells of proximal tubules in normal renal tissue. MAO-A was absent or very low in epithelial cells of distal tubules and glomerular capsule, as well as in endothelial cells of renal vessels.
  
  
  CONCLUSIONS
  Taken together, our results and findings of other studies show that MAO-A expression in high-grade tumours may have a direct role in maintaining a dedifferentiated phenotype and promoting aggressive behaviour. The ability of clorgyline (an MAO-A inhibitor) to counteract oncogenic pathways and promote differentiation suggests that MAO-A inhibitors, which have been used for many years in clinical practise for treating neurological disorders, could be therapeutic options for advanced stages of tumours.
authors.affiliation: Department of Anatomy, P J Šafárik University, Faculty of Medicine, Košice, Slovak Republic.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Hodorová
authors.forename: Silvia
authors.initials: S
authors.lastname: Rybárová
authors.forename: Janka
authors.initials: J
authors.lastname: Vecanová
authors.forename: Peter
authors.initials: P
authors.lastname: Solár
authors.forename: Iveta
authors.initials: I
authors.lastname: Domorákova
authors.forename: Marián
authors.initials: M
authors.lastname: Adamkov
authors.forename: Jozef
authors.initials: J
authors.lastname: Mihalik
mesh_terms: D000368:Aged; D002292:Carcinoma, Renal Cell / Q000201:enzymology* / Q000473:pathology*; D003593:Cytoplasm / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000201:enzymology / Q000473:pathology; D007680:Kidney Neoplasms / Q000201:enzymology* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D008995:Monoamine Oxidase / Q000378:metabolism*; D060787:Neoplasm Grading
chemical_list: D008995:Monoamine Oxidase; C579458:monoamine oxidase A, human