Clinical relevance of EMT in eyelid sebaceous gland carcinoma: an immunohistochemical and molecular study

Abstract

Purpose: Sebaceous gland carcinoma (SGC) is the most common malignant eyelid tumor with a high rate of incidence in Asia.Invasion and metastasis in several carcinomas is promoted by ‘Epithelial Mesenchymal Transition’ (EMT) where epithelial cells acquire a mesenchymal phenotype.It is mediated by transcription factors like Slug,ZEB1 & ZEB2 which causes loss of cell-cell adhesion molecule E-cadherin.The present study was designed to determine the status of EMT markers Slug,ZEB1,ZEB2 and E-cadherin and to correlate with high risk features of eyelid SGC.

Methods: Prospective analysis of 30 eyelid SGC patients was undertaken. Clinicopathological features were noted and H&E stained sections were reviewed to confirm the diagnosis.AJCC staging (2009) was done and patients were followed up for 37 months(Mean: 22.5±9.08).Immunohistochemistry(IHC) was performed using antibodies against ZEB1,ZEB2,Slug and E-cadherin.mRNA analysis by quantitative Real Time PCR was performed in all the tumour samples and adjoining normal skin tissues.Results were correlated with high risk features and follow up data.Statistical analysis was performed using Fisher Exact and Spearman’s Rank Correlation Tests.

Results: Mean age of patients was 58.9±13.2yrs (male:female ratio1.1:1).IHC and mRNA analysis revealed ZEB2,ZEB1 and Slug overexpression in 67%(20/30),40%(12/30) and 10%(3/30) cases respectively.E-cadherin loss was seen in 63%(19/30) cases.IHC expression of all 4 EMT markers significantly correlated with mRNA levels.ZEB2 overexpression was significantly associated with high risk features like poor histological differentiation (P=0.017) & pagetoid spread (P=0.023),whereas E-cadherin loss was significantly associated with large tumour size(P=0.023) & pagetoid spread (P=0.018).Both ZEB2 overexpression and E-cadherin loss were present in 88%(7/8) cases with recurrence.ZEB2 overexpression was also seen in 75%(6/8) cases with lymph node metastasis.There was a significant inverse correlation between ZEB2 and E-cadherin expression (P=0.038).Other EMT markers ZEB1 and Slug did not correlate with any clinicopathological high risk features.

Conclusions: EMT is an important phenomenon in eyelid SGC which could be responsible for its aggressive behaviour.Both ZEB2 and E-cadherin are important biomarkers for detection of high risk SGC cases.Further validation on a larger series of cases,with longer follow up is however necessary.