title: Reappraisal of KIT mutation in adenoid cystic carcinomas of the salivary gland.
abstract: BACKGROUND
  While overexpression of KIT protein has been well documented in adenoid cystic carcinomas (ACCs), mutation of KIT gene has been a controversial issue. We wanted to evaluate clinical value of the KIT mutation and protein expression in ACC.
  
  
  METHODS
  We analyzed 33 cases of ACC. Gene mutations in KIT exons 9, 11, 13, and 17 were analyzed using paraffin-embedded tissue, and two different sets of primers with direct sequencing after polymerase chain reaction (PCR) for exon 9, 11, 13, and 17, and cloning of PCR products for exon 11. KIT protein expression was assessed by immunohistochemistry. The correlation between clinicopathological findings and these biomarkers was analyzed.
  
  
  RESULTS
  No KIT mutation was observed in all of the 33 cases. With one primer set, KIT mutation was found in nine of 33 cases (27.3%). However, these mutations were not reproducible in the experiment using another primer set. KIT protein overexpression was detected in 22 of 33 patients (66.7%). KIT protein expression was not statistically correlated with either clinicopathological factors or survival. Patients with metastasis showed a tendency of longer progression-free survival (P = 0.052) and overall survival (P = 0.080) when the tumor overexpressed KIT protein.
  
  
  CONCLUSIONS
  This study supports that mutational study using paraffin-embedded tissue should be interpreted with great caution. KIT gene mutation is very rare in ACC, and gene mutation is not the cause of protein overexpression. KIT protein expression may have a potential value for better prognostic factor in patients with metastasis.
authors.affiliation: Department of Pathology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea.
authors.forename: Ji-Youn
authors.initials: JY
authors.lastname: Sung
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Ahn
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Kwon
authors.forename: Hansin
authors.initials: H
authors.lastname: Jeong
authors.forename: Chung-Hwan
authors.initials: CH
authors.lastname: Baek
authors.forename: Young-Ik
authors.initials: YI
authors.lastname: Son
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Ahn
authors.forename: Keunchil
authors.initials: K
authors.lastname: Park
authors.forename: Myung-Ju
authors.initials: MJ
authors.lastname: Ahn
authors.forename: Young-Hyeh
authors.initials: YH
authors.lastname: Ko
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003528:Carcinoma, Adenoid Cystic / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009361:Neoplasm Invasiveness / Q000235:genetics; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics* / Q000378:metabolism; D012468:Salivary Gland Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D019009:Proto-Oncogene Proteins c-kit