title: Clinicopathological and prognostic significance of GPX2 protein expression in esophageal squamous cell carcinoma.
abstract: Chaoshan region, a littoral area of Guangdong province in southern China, has a high incidence of esophageal squamous cell carcinoma (ESCC). At present, the prognosis of ESCC is still very poor, therefore, there is urgent need to seek valuable molecular biomarker for prognostic evaluation to guide clinical treatment. GPX2, a selenoprotein, was exclusively expressed in gastrointestinal tract and has an anti-oxidative damage and anti-tumour effect in the progress of tumourigenesis.
  
  
  
  We collected 161 ESCC patients samples, among which 83 patients were followed up. We employed immunochemistry analysis, western blotting and quantitative real-time PCR for measuring the expression of GPX2 within ESCC samples. We analysed the relationship between the expression of GPX2 and clinicopathological parameters of 161 patients with ESCC by Chi-square or Fisher's exact test. The survival analysis of GPX2 expression within ESCC tissues was evaluated by the Kaplan-Meier method and Cox-regression.
  
  
  
  A significant higher expression level of GPX2 was detected in tumour tissues compared to that in non-tumour tissues (P < 0.001). Moreover, GPX2 expression has statistically significant difference in the tumour histological grade of ESCC (P < 0.001), while there was no statistically significant difference in age, sex, tumour size, tumour location, gross morphology and clinical TNM stages (P > 0.05). Meanwhile, the expression of GPX2 protein was obviously down-regulated within poorly differentiated ESCC. Last, survival analysis revealed that tumour histological grade and clinical TNM stages, both of the clinical pathological parameters of ESCC, were associated with the prognosis of patients with ESCC (respectively, P = 0.009, HR (95 % CI) = 1.885 (1.212 ~ 2.932); P = 0.007, HR (95 % CI) = 2.046 (1.318 ~ 3.177)). More importantly, loss expression of GPX2 protein predicted poor prognosis in patients with ESCC (P < 0.001, HR (95 % CI) = 5.700 (2.337 ~ 13.907)).
  
  
  
  Collectively, these results suggested that the expression of GPX2 was significantly up-regulated within ESCC tumour tissues. GPX2 might be an important predictor for the prognosis of ESCC and a potential target for intervention and treatment of ESCC.
authors.affiliation: Department of Pathology and Institute of Clinical Pathology, Shantou University Medical College, Shantou, Guangdong, People's Republic of China.
authors.forename: Zhijin
authors.initials: Z
authors.lastname: Lei
authors.affiliation: Department of Pathology and Institute of Clinical Pathology, Shantou University Medical College, Shantou, Guangdong, People's Republic of China.|Forensic Identification Center of Shantou University, Shantou University Medical College, Shantou, Guangdong, People's Republic of China.
authors.forename: Dongping
authors.initials: D
authors.lastname: Tian
authors.affiliation: Department of Pathology and Institute of Clinical Pathology, Shantou University Medical College, Shantou, Guangdong, People's Republic of China.
authors.forename: Chong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Pathology and Institute of Clinical Pathology, Shantou University Medical College, Shantou, Guangdong, People's Republic of China.
authors.forename: Shukun
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Department of Pathology and Institute of Clinical Pathology, Shantou University Medical College, Shantou, Guangdong, People's Republic of China. minsu@stu.edu.cn.|Forensic Identification Center of Shantou University, Shantou University Medical College, Shantou, Guangdong, People's Republic of China. minsu@stu.edu.cn.
authors.forename: Min
authors.identifier: 0000-0003-3589-9573
authors.initials: M
authors.lastname: Su
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology; D002681:China; D004938:Esophageal Neoplasms / Q000378:metabolism* / Q000473:pathology; D000077277:Esophageal Squamous Cell Carcinoma; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005979:Glutathione Peroxidase / Q000378:metabolism*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D015996:Survival Rate; D015854:Up-Regulation
chemical_list: C117436:GPX2 protein, human; D005979:Glutathione Peroxidase
keywords: Clinicopathological parameters; ESCC; GPX2; Overexpression; Prognosis