Subcellular differential expression of Ep-ICD in oral dysplasia and cancer is associated with disease progression and prognosis

Abstract

Background: Identification of patients with oral dysplasia at high risk of cancer development and oral squamous cell carcinoma (OSCC) at increased risk of disease recurrence will enable rigorous personalized treatment. Regulated intramembranous proteolysis of Epithelial cell adhesion molecule (EpCAM) resulting in release of its intracellular domain Ep-ICD into cytoplasm and nucleus triggers oncogenic signaling. We analyzed the expression of Ep-ICD in oral dysplasia and cancer and determined its clinical significance in disease progression and prognosis.

Methods: In a retrospective study, immunohistochemical analysis of nuclear and cytoplasmic Ep-ICD and EpEx (extracellular domain of EpCAM), was carried out in 115 OSCC, 97 oral dysplasia and 105 normal oral tissues, correlated with clinicopathological parameters and disease outcome over 60 months for oral dysplasia and OSCC patients. Disease-free survival (DFS) was determined by Kaplan-Meier method and multivariate Cox regression analysis.

Results: In comparison with normal oral tissues, significant increase in nuclear Ep-ICD and membrane EpEx was observed in dysplasia, and OSCC (p = 0.013 and < 0.001 respectively). Oral dysplasia patients with increased overall Ep-ICD developed cancer in short time period (mean = 47 months; p = 0.044). OSCC patients with increased nuclear Ep-ICD and membrane EpEx had significantly reduced mean DFS of 33.7 months (p = 0.018).

Conclusions: Our study provided clinical evidence for Ep-ICD as a predictor of cancer development in patients with oral dysplasia and recurrence in OSCC patients, suggesting its potential utility in enhanced management of those patients detected to have increased risk of progression to cancer and recurrence in OSCC patients.

Keywords: Dysplasia; Ep-ICD; EpCAM; Oral cancer; Oral lesion; Prognosis; Squamous cell carcinoma.

Fig. 1

Immunohistochemical analysis of Ep-ICD in oral tissues. Paraffin-embedded sections of histologically normal mucosa, oral dysplasia and OSCC were stained using anti-Ep-ICD monoclonal antibody as described in Methods section. Panel presents representative photomicrographs of Ep-ICD staining. a Shows predominantly Ep-ICD_Cyt staining in normal oral mucosa with some stromal staining; b Increased cytoplasmic and nuclear staining is observed in dysplasia; c OSCC also shows cytoplasmic and nuclear staining; d No immunostaining was observed in tissue sections used as negative controls where the primary antibody was replaced by isotype specific IgG; while a known OSCC showing Ep-ICD_Nuc and Ep-ICD_Cyt was used as a positive control (Data not shown); (a, b, c, d, original magnification x 200)

Fig. 2

Immunohistochemical analysis of EpEx in oral tissues. Paraffin-embedded sections of histologically normal mucosa, oral dysplasia and OSCC were stained using anti-EpEx monoclonal antibody as described in Methods section. Panel represents (a) normal oral mucosa showing no detectable EpEx_Mem immunostaining; b Oral dysplasia showing intense EpEx_Mem staining; c OSCC section illustrating reduced EpEx_Mem in tumor cells; d OSCC section used as a negative control, showing no EpEx immunostaining in tumor cells where the primary antibody was replaced by isotype specific IgG (A-D original magnification x 200)

Fig. 3

Kaplan Meier survival analysis of Ep-ICD in Oral Dysplasia and OSCC patients. a Dysplasia patients with increased overall (nuclear and cytoplasmic) Ep-ICD score had significantly reduced mean cancer free survival of 47 months as compared to patients with low overall Ep-ICD score (mean cancer free survival = 57.5 months; p = 0.044); b OSCC patients with increased Ep-ICD_Nuc and EpEx_Mem score had significantly reduced mean disease free survival (DFS) of 33.7 months as compared to patients with decreased Ep-ICD_Nuc and EpEx_Mem score (mean DFS = 46.3 months; p = 0.018)