title: Relationship between microRNA expression levels and histopathological features of dysplasia in oral leukoplakia.
abstract: BACKGROUND
  Increased expression of microRNAs (miRNAs), miR-21, miR-345, and miR-181b has been demonstrated in oral leukoplakia (OL) that progresses to oral squamous cell carcinoma (OSCC), suggesting a miRNA signature with potential prognostic value. On the basis of these findings, this pilot study aimed to investigate the cytological and histopathological features that are used to grade oral dysplasia and determine associations with the expression of these 3 potentially cancer-related miRNAs. We also compared the expression levels of these miRNAs in OL with normal oral mucosa and OSCC.
  
  
  METHODS
  We evaluated miRNA expression by qPCR in 22 samples of OL demonstrating different grades of dysplasia, as well as 17 cases of OSCC, and 6 samples of normal oral mucosa. We associated the miRNAs expression profiles with cytological and histopathological features of OL.
  
  
  RESULTS
  OSCC cases showed increased expression of all 3 miRNAs when compared with OL and normal oral mucosa. Increased expression of miR-21 was also observed in OL when compared with normal oral mucosa. We found a higher expression of miR-21 and miR-181b in OL that presented with an increased number of mitotic figures, increased nuclear/cytoplasmic ratio, or hyperchromasia. Increased expression of miR-21 was also detected in OL with abnormally superficial mitosis. Higher expression of miR-345 was observed in OL with an increased number and size of nucleoli or increased nuclear/cytoplasmic ratio.
  
  
  CONCLUSIONS
  In conclusion, the present study shows that some cytological and histopathological parameters used to grade dysplasia are associated with altered miRNA expression.
authors.affiliation: Department of Oral Pathology, School of Dentistry, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: João A R
authors.initials: JA
authors.lastname: Brito
authors.forename: Carolina C
authors.initials: CC
authors.lastname: Gomes
authors.forename: André L S
authors.initials: AL
authors.lastname: Guimarães
authors.forename: Kelma
authors.initials: K
authors.lastname: Campos
authors.forename: Ricardo S
authors.initials: RS
authors.lastname: Gomez
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002466:Cell Nucleolus / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007972:Leukoplakia, Oral / Q000737:chemistry* / Q000473:pathology; D008297:Male; D035683:MicroRNAs / Q000032:analysis*; D008875:Middle Aged; D008938:Mitosis; D009061:Mouth Mucosa / Q000737:chemistry; D009062:Mouth Neoplasms / Q000737:chemistry / Q000473:pathology; D010865:Pilot Projects; D011230:Precancerous Conditions / Q000737:chemistry / Q000473:pathology
chemical_list: C524940:MIRN21 microRNA, human; C561417:MIRN345 microRNA, human; C540193:MIrn181 microRNA, human; D035683:MicroRNAs
keywords: dysplasia; microRNA; oral cancer; oral leukoplakia