Characterization of tumor-suppressive function of SOX6 in human esophageal squamous cell carcinoma

Clin Cancer Res. 2011 Jan 1;17(1):46-55. doi: 10.1158/1078-0432.CCR-10-1155. Epub 2010 Nov 17.

Abstract

Purpose: By using cDNA microarray analysis, we identified a transcriptional factor, SOX6, was frequently downregulated in esophageal squamous cell carcinoma (ESCC). The aim of this study is to investigate the role of SOX6 in human esophageal cancer development, and to examine the prevalence and clinical significance of SOX6 downregulation in ESCC.

Experimental design: Expressions of SOX6 mRNA in 50 ESCCs and SOX6 protein in 300 ESCCs were investigated by semiquantitative RT-PCR and immunohistochemistry, respectively. The tumor-suppressive function of SOX6 was characterized by cell growth, foci formation, wound-healing and cell invasive assays, and tumor xenograft experiment. Western blot analysis was applied to detect protein expression levels.

Results: SOX6 was frequently downregulated in primary ESCCs in both mRNA level (29/50, 58%) and protein level (149/219, 68.0%), which was significantly associated with the poor differentiation (P = 0.029), lymph node metastases (P = 0.014), advanced TNM stage (P = 0.000), and disease-specific survival (P < 0.001). Multivariate analysis indicated that the downregulation of SOX6 (P = 0.000) was a significant independent prognostic factors for ESCC. Functional studies showed that SOX6 was able to suppress both in vitro and in vivo tumorigenic ability of ESCC cells. The tumor-suppressive mechanism of SOX6 was associated with its role in G1/S cell-cycle arrest by upregulating expressions of p53 and p21(WAF1/CIP1) and downregulating expressions of cyclin D1/CDK4, cyclin A, and β-catenin.

Conclusions: We provided the first evidence that SOX6 is a novel tumor-suppressor gene in ESCC development and is a potential prognostic marker in ESCC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carcinoma, Squamous Cell / diagnosis
  • Carcinoma, Squamous Cell / genetics*
  • Carcinoma, Squamous Cell / metabolism
  • Cell Line, Tumor
  • Down-Regulation*
  • Esophageal Neoplasms / diagnosis
  • Esophageal Neoplasms / genetics*
  • Esophageal Neoplasms / metabolism
  • Female
  • Humans
  • Immunohistochemistry
  • Male
  • Mice
  • Mice, Nude
  • Middle Aged
  • Multivariate Analysis
  • Oligonucleotide Array Sequence Analysis
  • Prognosis
  • RNA, Messenger / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • SOXD Transcription Factors / genetics*
  • SOXD Transcription Factors / metabolism*
  • Survival Analysis
  • Tumor Suppressor Proteins / genetics*
  • Tumor Suppressor Proteins / metabolism*
  • Xenograft Model Antitumor Assays

Substances

  • RNA, Messenger
  • SOX6 protein, human
  • SOXD Transcription Factors
  • Tumor Suppressor Proteins