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Open Access Highly Accessed Research article

SNAI1 expression and the mesenchymal phenotype: an immunohistochemical study performed on 46 cases of oral squamous cell carcinoma

Joerg Schwock1, Grace Bradley2, James C Ho3, Bayardo Perez-Ordonez1, David W Hedley1, Jonathan C Irish4 and William R Geddie1*

Author affiliations

1 Department of Laboratory Medicine & Pathobiology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada

2 Faculty of Dentistry, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada

3 Division of Applied Molecular Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada

4 Department of Otolaryngology, Head and Neck Surgery, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada

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Citation and License

BMC Clinical Pathology 2010, 10:1  doi:10.1186/1472-6890-10-1

Published: 5 February 2010

Abstract

Background

SNAI1 can initiate epithelial-mesenchymal transition (EMT), leading to loss of epithelial characteristics and, in cancer, to invasion and metastasis. We hypothesized that SNAI1 reactivation occurs in oral squamous cell carcinoma (OSCC) where it might also be associated with focal adhesion kinase (FAK) expression and p63 loss.

Methods

Immunohistochemistry was performed on 46 tumors and 26 corresponding lymph node metastases. Full tissue sections were examined to account for rare and focal expression. Clinical outcome data were collected and analyzed.

Results

SNAI1-positivity (nuclear, ≥ 5% tumor cells) was observed in 10 tumors and 5 metastases (n = 12 patients). Individual SNAI1(+) tumor cells were seen in primary tumors of 30 patients. High level SNAI1 expression (>10% tumor cells) was rare, but significantly associated with poor outcome. Two cases displayed a sarcomatoid component as part of the primary tumor with SNAI1(+)/FAK(+)/E-cadherin(-)/p63(-) phenotype, but disparate phenotypes in corresponding metastases. All cases had variable SNAI1(+) stroma. A mesenchymal-like immunoprofile in primary tumors characterized by E-cadherin loss (n = 29, 63%) or high cytoplasmic FAK expression (n = 10, 22%) was associated with N(+) status and tumor recurrence/new primary, respectively.

Conclusions

SNAI1 is expressed, although at low levels, in a substantial proportion of OSCC. High levels of SNAI1 may herald a poor prognosis and circumscribed SNAI1 expression can indicate the presence of a sarcomatoid component. Absence of p63 in this context does not exclude squamous tumor origin. Additional EMT inducers may contribute to a mesenchymal-like phenotype and OSCC progression.