title: KRAS, BRAF and PIK3CA mutations and the loss of PTEN expression in Chinese patients with colorectal cancer.
abstract: BACKGROUND
  To investigate the frequency and relationship of the KRAS, BRAF and PIK3CA mutations and the loss of PTEN expression in Chinese patients with colorectal cancer (CRC).
  
  
  RESULTS
  Genomic DNA was extracted from the formalin-fixed paraffin-embedded (FFPE) tissues of 69 patients with histologically confirmed CRC. Automated sequencing analysis was conducted to detect mutations in the KRAS (codons 12, 13, and 14), BRAF (codon 600) and PIK3CA (codons 542, 545 and 1047). PTEN protein expression was evaluated by immunohistochemistry on 3 mm FFPE tissue sections. Statistical analysis was carried out using SPSS 16.0 software. The frequency of KRAS, BRAF and PIK3CA mutations and loss of PTEN expression was 43.9% (25/57), 25.4% (15/59), 8.2% (5/61) and 47.8% (33/69), respectively. The most frequent mutation in KRAS, BRAF and PIK3CA was V14G (26.7% of all mutations), V600E (40.0% of all mutations) and V600L (40.0% of all mutations), and H1047L (80.0% of all mutations), respectively. Six KRAS mutant patients (24.0%) harbored BRAF mutations. BRAF and PIK3CA mutations were mutually exclusive. No significant correlation was observed between the four biomarkers and patients' characteristics.
  
  
  CONCLUSIONS
  BRAF mutation rate is much higher in this study than in other studies, and overlap a lot with KRAS mutations. Besides, the specific types of KRAS and PIK3CA mutations in Chinese patients could be quite different from that of patients in other countries. Further studies are warranted to examine their impact on prognosis and response to targeted treatment.
authors.affiliation: Department of Epidemiology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Chen
authors.initials: C
authors.lastname: Mao
authors.forename: Junhua
authors.initials: J
authors.lastname: Zhou
authors.forename: Zuyao
authors.initials: Z
authors.lastname: Yang
authors.forename: Yafang
authors.initials: Y
authors.lastname: Huang
authors.forename: Xinyin
authors.initials: X
authors.lastname: Wu
authors.forename: Hong
authors.initials: H
authors.lastname: Shen
authors.forename: Jinling
authors.initials: J
authors.lastname: Tang
authors.forename: Qing
authors.initials: Q
authors.lastname: Chen
mesh_terms: D002681:China; D058534:Class I Phosphatidylinositol 3-Kinases; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009367:Neoplasm Staging; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics
chemical_list: C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins