title: Decreased expression of 14-3-3 σ, an early event of malignant transformation of respiratory epithelium, also facilitates progression of squamous cell lung cancer.
abstract: BACKGROUND
  It has been shown that 14-3-3 σ serves as a tumor suppressor gene, and is downregulated in various tumor tissues. However, the role of 14-3-3 σ during the initiation and progression of lung squamous cell carcinoma (SqCC) is not well understood.
  
  
  METHODS
  The expression status of 14-3-3 σ in archival tissue samples from 40 lung SqCC patients (36 with normal bronchia, 19 squamous metaplasia, and 17 dysplasia/carcinoma in situ, in their tissue samples) was examined by immunohistochemical analysis. The proliferation rate and tumor formation ability of the H520 cell transfected with 14-3-3 σ was tested with methyl thiazolyl tetrazolium assay and nude mice subcutaneous injection, respectively.
  
  
  RESULTS
  In the normal bronchial epithelia, 14-3-3 σ was highly expressed, whereas it was significantly decreased in precancerous and cancerous tissues. Compared with matched invasive cancer tissues, the expression level of 14-3-3 σ in squamous metaplasia was significantly higher (P = 0.049), while that in dysplasia/carcinoma in situ showed no significant changes (P = 0.135). Statistical analysis showed that the expression level of 14-3-3 σ in tumor tissue was associated with the differentiation grade of the tumor (P = 0.001) and the prognosis of the patient (P = 0.003). The overexpression of 14-3-3 σ significantly suppressed the proliferation of H520 cells in vitro and in vivo.
  
  
  CONCLUSIONS
  The inactivation of 14-3-3 σ may be a very early event in tumorigenesis and could facilitate the initiation and progression of lung SqCC in a sustainable way.
authors.affiliation: Department of Thoracic Surgery, Liaoning Cancer Hospital and Institute Shenyang, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Sun
authors.affiliation: Department of Thoracic Surgery, Liaoning Cancer Hospital and Institute Shenyang, China.
authors.forename: Yongkai
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Pathology, Liaoning Cancer Hospital and Institute Shenyang, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Huang
authors.affiliation: Department of Pathology, Liaoning Cancer Hospital and Institute Shenyang, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Thoracic Surgery, Liaoning Cancer Hospital and Institute Shenyang, China.
authors.forename: Yinan
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Thoracic Surgery, Liaoning Cancer Hospital and Institute Shenyang, China.
authors.forename: Jianqiao
authors.initials: J
authors.lastname: Ding
authors.affiliation: Department of Thoracic Surgery, Liaoning Cancer Hospital and Institute Shenyang, China.
authors.forename: Yongyu
authors.initials: Y
authors.lastname: Liu
keywords: 14-3-3 σ; lung squamous cell carcinoma; precancerous lesion; prognosis