title: Increased expression of USP22 is associated with disease progression and patient prognosis of salivary duct carcinoma.
abstract: OBJECTIVE
  Ubiquitin-specific protease 22 (USP22) could exhibit a critical function in pathological processes, including oncogenesis and cell cycle progression. This study examines the protein expression of USP22 in salivary duct carcinoma (SDC) in association with patient survival and other clinicopathologic parameters.
  
  
  METHODS
  Quantitative RT-PCR and immunohistochemistry (IHC) were used to determine the expression of USP22 protein in 44 SDCs in comparison with 20 non-cancerous salivary tissues. Furthermore, we analyzed the correlation between the expression of the USP22 protein and various clinicopathologic factors including survival status of patients with SDC.
  
  
  RESULTS
  The incidence of positive USP22 expression was 63.7% in 44 SDC tissues. The mRNA level of USP22 expression in SDC samples was significantly higher than that in non-cancerous salivary tissues (P < 0.001), which was consistent with the IHC result (P < 0.001). Moreover, statistical analysis showed that positive USP22 expression was positively related to pT classification, pN classification and AJCC stage. Notably, high USP22 expression was significantly associated with shorter overall survival (P = 0.023) and disease-specific survival (P = 0.019). Multivariate Cox regression analysis revealed that USP22 expression level was an independent prognostic factor for both overall survival (P < 0.001) and disease-free survival (P < 0.001).
  
  
  CONCLUSIONS
  Our results indicate that activation of USP22 correlates with SDC progression and therapy failure. Overexpression of USP22 may contribute to the progression of SDC and thus may serve as a new molecular marker to predict the prognosis of SDC patients.
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin 150001, Heilongjiang, People's Republic of China.
authors.forename: Songlin
authors.initials: S
authors.lastname: Piao
authors.forename: Jie
authors.initials: J
authors.lastname: Ma
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Yanlong
authors.initials: Y
authors.lastname: Liu
authors.forename: Minghui
authors.initials: M
authors.lastname: Zhang
authors.forename: Hongying
authors.initials: H
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Guo
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.forename: Fulin
authors.initials: F
authors.lastname: Guo
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D018987:Salivary Ducts / Q000473:pathology*; D012468:Salivary Gland Neoplasms / Q000378:metabolism* / Q000473:pathology; D013869:Thiolester Hydrolases / Q000378:metabolism*; D016896:Treatment Outcome; D043222:Ubiquitin Thiolesterase
chemical_list: D014408:Biomarkers, Tumor; D013869:Thiolester Hydrolases; D043222:Ubiquitin Thiolesterase; C527170:Usp22 protein, human
keywords: Immunohistochemistry; Prognosis; Quantitative RT-PCR; Salivary duct carcinoma; USP22