Do INI1 and E-cadherin Expression Loss Have Any Significance in Endometrial Carcinomas?

Objective: Endometrial carcinoma (EC) is a highly heterogeneous malignancy in terms of morphology, clinical course, response to treatment and prognosis. This study aimed to investigate the loss of INI1 (SWI/SNF family member) and E-cadherin expression in type 1 and 2 ECs to elucidate the mechanisms that may elucidate on the differences in pathogenesis and prognosis between lowand high-grade histological types. Methods: Immunohistochemistry (IHC) was applied for INI1 and E-cadherin in 72 patients who underwent hysterectomy for EC. Loss of INI1 and E-cadherin expression was compared between subjects with lowand high-grade EC. Results: A total of 63 patients had type 1 (endometrioid) and nine had type 2 (non-endometrioid) tumours. IHC staining revealed loss of INI1 expression in eight cases. While three of these cases were serous carcinoma, three were endometrioid carcinoma with villoglandular pattern and two were grade 3 endometrioid carcinoma. A significant difference was found in the loss of INI1 expression between low-grade (G1-G2) and highgrade (G3 endometrioid carcinoma and non-endometrioid carcinoma) tumours (p=0.004). Loss of expression was observed only in one case of dedifferentiated carcinoma in IHC staining performed for E-cadherin in 72 cases. Conclusion: A significantly greater loss of INI1 expression was observed in high-grade compared with low-grade endometrial carcinoma. This finding confirms that INI1 loss is a poor prognostic factor in these tumours as in other tumours reported in the literature and sheds light on the different pathogeneses seen in high-grade EC. To the best of our knowledge, this is the first systematic study to investigate INI1 loss in different types of endometrial carcinoma. Our results support the notion that SWI/SNF chromatin remodelling complex plays a role in the pathogenesis of high-grade EC and type 1 endometrioid carcinoma with villoglandular pattern.