title: DNA base excision repair proteins APE-1 and XRCC-1 are overexpressed in oral tongue squamous cell carcinoma.
abstract: BACKGROUND
  DNA repair systems play a critical role in protecting the human genome from damage caused by carcinogens. Modifications in DNA repair genes may be responsible for tumor development and resistance of malignant cells to chemotherapeutic agents. The major pathway for oxidative DNA damage repair is the base excision repair pathway. This study aimed to assess the immunoexpression of DNA repair proteins APE-1 and XRCC-1 and its association with clinical, histologic, and survival parameters in oral tongue squamous cell carcinoma, to investigate a possible role for those proteins in tumor behavior.
  
  
  METHODS
  The expression of APE-1 and XRCC-1 was evaluated by immunohistochemistry in 82 cases of oral tongue squamous cell carcinoma. Histopathological grading was performed for each case. Pearson's chi-square and Fisher's exact tests were used to determine the association between protein expressions and clinicopathological features of tumors, whereas Kaplan-Meier curves and Cox regression were used to analyze disease-specific and disease-free survival. Statistical significance was set at P ≤ 0.05.
  
  
  RESULTS
  APE-1 was highly expressed in the nucleus and cytoplasm in 64.6% of cases, and XRCC-1 showed overexpression only in the nucleus in 61% of cases. High expression of XRCC-1 was significantly associated with tumors at early clinical stages (I and II, P < 0.01) and nodal status (P = 0.03). Both proteins were not associated with other clinical parameters, histopathological grading, or survival.
  
  
  CONCLUSIONS
  DNA base excision repair proteins APE-1 and XRCC-1 are upregulated in oral tongue squamous cell carcinoma, and XRCC-1 expression is associated with better clinical staging and nodal status.
authors.affiliation: Oral Pathology Post Graduate Program, Department of Dentistry, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: Thalita
authors.initials: T
authors.lastname: Santana
authors.affiliation: Oral Pathology Post Graduate Program, Department of Dentistry, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: Melka Coêlho
authors.initials: MC
authors.lastname: Sá
authors.affiliation: Oral Pathology Post Graduate Program, Department of Dentistry, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: Edilmar
authors.initials: E
authors.lastname: de Moura Santos
authors.affiliation: Oral Pathology Post Graduate Program, Department of Dentistry, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: Hébel Cavalcanti
authors.initials: HC
authors.lastname: Galvão
authors.affiliation: Oral Diagnosis, School of Dentistry, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Ricardo D
authors.initials: RD
authors.lastname: Coletta
authors.affiliation: Oral Pathology Post Graduate Program, Department of Dentistry, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: Roseana de Almeida
authors.initials: RA
authors.lastname: Freitas
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D002467:Cell Nucleus / Q000235:genetics; D002648:Child; D003593:Cytoplasm / Q000235:genetics; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000235:genetics*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D012307:Risk Factors; D014062:Tongue Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D015854:Up-Regulation; D000076105:X-ray Repair Cross Complementing Protein 1 / Q000235:genetics*; D055815:Young Adult
chemical_list: D000076105:X-ray Repair Cross Complementing Protein 1; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase
keywords: DNA repair; immunohistochemistry; oral cancer