title: Ubiquitin-specific protease 7 expression is a prognostic factor in epithelial ovarian cancer and correlates with lymph node metastasis.
abstract: OBJECTIVE
  Ubiquitin-specific protease 7 (USP7) is a common target of herpesviruses and is important in the DNA damage response, which is also upregulated in several cancers, including prostate, colon, liver, and lung cancers. However, less is known about its expression in ovarian cancer tissues. The role of USP7 in epithelial ovarian cancer (EOC) has not yet been investigated.
  
  
  METHODS
  We recruited 141 patients from Linyi People's Hospital between June 1999 and June 2013, all pathologically diagnosed with primary EOC. Their clinical data were collected, and the expression of USP7 in the tumor tissues was determined using immunohistochemistry. The correlations between USP7 expression and the clinicopathological variables of patients with EOC were assessed using Spearman's rank correlation test. Kaplan-Meier analysis and Cox regression analysis were used to identify the prognosis value of USP7. The function of USP7 in the EOC cells was also detected in vitro.
  
  
  RESULTS
  Among the 141 cases, USP7 expression was high in 59 EOC samples (41.8%), and was significantly correlated with lymphatic invasion; USP7 can act as independent prognostic indicator for the overall survival (OS) of EOC, and its high expression was associated with poor OS rate. The RNA inteference and overexpression assays indicated that USP7 can positively regulate the ovarian cell vitality and invasion process.
  
  
  CONCLUSIONS
  Patients with EOC expressing high level of USP7 have worse OS compared with those with low USP7 expression. USP7 may be involved in the proliferation and invasion of EOC cells, and USP7 expression can serve as an independent predictor of EOC.
authors.affiliation: Department of Oncology, Linyi People's Hospital, Linyi, People's Republic of China.
authors.forename: Ming
authors.initials: M
authors.lastname: Ma
authors.affiliation: Department of Gynecology and Obstetrics, Linyi People's Hospital, Linyi, People's Republic of China.
authors.forename: Nina
authors.initials: N
authors.lastname: Yu
keywords: USP7; epithelial ovarian cancer; invasion; lymph node metastasis; prognosis