title: KRAS mutation associated with CD44/CD166 immunoexpression as predictors of worse outcome in metastatic colon cancer.
abstract: BACKGROUND
  Multiple stages of carcinogenesis in colon cancer encompass subpopulations of cancer stem cells (CSC), responsible for tumor cell transformation, growth and proliferation. CD44 and CD166 proteins are CSC markers associated with cell signaling, adhesion, migration, metastasis and lymphocytic response. The expression of CSC may be modulated by some factors, such as the KRAS gene mutation.
  
  
  OBJECTIVE
  Correlate the expression of CD44 and CD166 markers in metastatic colon adenocarcinoma and KRAS mutation status (wild-type/mutated) with clinical pathological features and patients' outcome.
  
  
  METHODS
  Fifty-eight samples of tumor tissue samples of metastatic colon adenocarcinoma were collected from patients treated with CapeOx at the HCFMRP-USP Clinical Oncology Service. Clinical and survival data were collected from medical records. KRAS status was determined by the polymerase chain reaction (PCR) technique, and analysis of immunohistochemical expression of CD44 and CD166 proteins was performed by tissue microarray.
  
  
  RESULTS
  The expression of CD44 and CD166 were positive in 41% and 43% of patients, respectively, and mutated KRAS was detected in 48% of patients. A significant association was found between CD166 and CD44 expression (p= 0.016), mainly in the wild-type KRAS group (p= 0.042) and patients over 65 years (p= 0.001). CD44-positive patients had 3.7-fold and 5.3-fold greater risk of liver metastasis and lung metastasis, respectively (p< 0.01), compared with CD44-negative patients. CD166-negative patients had 2.7 greater risk of lymph node involvement (0.03), compared with CD166-positive patients. KRAS mutation increased the risk of liver metastasis by 8 times (p< 0.01), and the risk of lung metastasis by 5 times (p= 0.04) in CD44-positive patients. KRAS mutation increased the risk of lymph node involvement by 8 times in CD166-negative patients (p= 0.0007).
  
  
  CONCLUSIONS
  An association between CD44 and CD166 expression was demonstrated in this study. Analysis of KRAS mutation combined with immunohistochemical expression of CD44 and CD166 identified subgroups of patients with colon adenocarcinoma at higher risk of lymph node involvement by the tumor and development of liver and lung metastasis.
authors.affiliation: Internal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Karen Bento
authors.initials: KB
authors.lastname: Ribeiro
authors.affiliation: Pathology and Legal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: da Silva Zanetti
authors.affiliation: Pathology and Legal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ribeiro-Silva
authors.affiliation: Internal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Liane
authors.initials: L
authors.lastname: Rapatoni
authors.affiliation: Internal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Harley Francisco
authors.initials: HF
authors.lastname: de Oliveira
authors.affiliation: Surgery and Anatomy Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Daniela Pretti
authors.initials: DP
authors.lastname: da Cunha Tirapelli
authors.affiliation: Surgery and Anatomy Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Sergio Britto
authors.initials: SB
authors.lastname: Garcia
authors.affiliation: Surgery and Anatomy Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Omar
authors.initials: O
authors.lastname: Feres
authors.affiliation: Surgery and Anatomy Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: José Joaquim Ribeiro
authors.initials: JJ
authors.lastname: da Rocha
authors.affiliation: Internal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Fernanda Maris
authors.initials: FM
authors.lastname: Peria
mesh_terms: D020410:Activated-Leukocyte Cell Adhesion Molecule / Q000378:metabolism*; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009154:Mutation; D060787:Neoplasm Grading; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D014411:Neoplastic Stem Cells / Q000378:metabolism; D063868:Patient Outcome Assessment; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018631:ras Proteins / Q000235:genetics*
chemical_list: D020410:Activated-Leukocyte Cell Adhesion Molecule; D014408:Biomarkers, Tumor; D018960:Hyaluronan Receptors; D018631:ras Proteins
keywords: Colon cancer; KRAS mutation; biomarker; cancer stem cell