Expression of SIP1 in oral squamous cell carcinomas: implications for E-cadherin expression and tumor progression
Maeda, G.; Chiba, T.; Okazaki, M.; Satoh, T.; Taya, Y.; Aoba, T.; Kato, K.; Kawashiri, S.; Imai, K.
International Journal of Oncology 27(6): 1535-1541
2005
ISSN/ISBN: 1019-6439 PMID: 16273209 Document Number: 584591
Loss of E-cadherin expression allows carcinoma cells to liberate from the primary site and enhances invasion and metastasis. The genetic aberration of E-cadherin is a rare event in sporadic carcinomas, and transcription repressors are considered to take a central role in E-cadherin loss. However, expression of E-cadherin repressors is largely dependent on tissue and cell type. To identify the repressor expressed in oral squamous carcinomas, we compared the expression levels of E-cadherin and repressors by real-time RT-PCR. Among the repressors including SNAIL, SLUG, SIP1, E12 and E47, SIP1 was inversely correlated to E-cadherin (P<0.05). Chromatin immunoprecipitation showed that SIPI specifically bound to the E-cadherin promoter region. SIP1 expression was immunohistochemically detected in 27.7% of 47 oral carcinomas, and SIP1-positive carcinomas did not express E-cadherin (P<0.01). Thirteen patients with SIP1 staining showed a lower disease-specific survival rate (P<0.05). Multivariate risk factor analysis demonstrated that SIP1 expression was an independent prognostic value for disease-specific overall survival (P<0.05). These results suggest that SIP1 contributes to the loss of E-cadherin expression and that detection of SIP1 expression is a predictive and prognostic tool in clinical management of oral carcinomas.