title: Increased expression of ERCC2 gene in head and neck cancer is associated with aggressive tumors: a systematic review and case-control study.
abstract: BACKGROUND
  The excision repair cross-complementation group 2 (ERCC2) ATP-dependent helicase is an essential member of the DNA repair pathway. It has been observed to be differentially expressed in different cancers, which shows its involvement in carcinogenesis.
  
  
  OBJECTIVE
  In the present study we have tried to determine the association of expression patterns of this gene with head and neck carcinogenesis.
  
  
  METHODS
  We first carried out a systematic review of the available studies on the role of ERCC2 in head and neck cancer (HNC). In order to test the hypothesis that the expression patterns of XPD/ERCC2 play a critical role in HNC pathogenesis, we then conducted a population based case-control study on 81 head and neck tumor samples and adjacent normal-tissue control samples. Reverse transcriptase polymerase chain reaction (RT-PCR) and quantitative polymerase chain reaction (qPCR) were used to assess ERCC2 deregulation at the mRNA level.
  
  
  RESULTS
  Expression analysis showed that the ERCC2 expression level was significantly upregulated (p&lt;0.05) in HNC tissues compared with adjacent normal tissues. Furthermore, the expression pattern of ERCC2 was correlated with the expression pattern of Ki-67 and a significant correlation (r = 0.230, p&lt;0.03) was observed between ERCC2 and Ki-67. Spearman's correlation also showed a significant correlation between ERCC2 expression and tumor stage (r = 0.271, p&lt;0.02) and grade (r = 0.228, p&lt;0.02) of HNC.
  
  
  CONCLUSIONS
  Our data suggest that deregulation of ERCC2 in HNC has the potential to predict a more aggressive cancer phenotype and may be considered a possible biomarker for improved diagnosis and prognosis of HNC.
authors.affiliation: Cancer Genetics and Epigenetics Research Group, Department of Biosciences, COMSATS Institute of Information Technology, Islamabad - Pakistan.
authors.forename: Maryam
authors.initials: M
authors.lastname: Zafeer
authors.affiliation: Cancer Genetics and Epigenetics Research Group, Department of Biosciences, COMSATS Institute of Information Technology, Islamabad - Pakistan.
authors.forename: Ishrat
authors.initials: I
authors.lastname: Mahjabeen
authors.affiliation: Cancer Genetics and Epigenetics Research Group, Department of Biosciences, COMSATS Institute of Information Technology, Islamabad - Pakistan.
authors.forename: Mahmood Akhtar
authors.initials: MA
authors.lastname: Kayani
mesh_terms: D014408:Biomarkers, Tumor / Q000096:biosynthesis* / Q000235:genetics; D016022:Case-Control Studies; D015972:Gene Expression Regulation, Neoplastic; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000473:pathology; D006801:Humans; D019394:Ki-67 Antigen / Q000096:biosynthesis* / Q000235:genetics; D009367:Neoplasm Staging; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D051759:Xeroderma Pigmentosum Group D Protein / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D012333:RNA, Messenger; D051759:Xeroderma Pigmentosum Group D Protein; C497292:ERCC2 protein, human