Co-Expression of Lewis y Antigen with Human Epididymis Protein 4 in Ovarian Epithelial Carcinoma

Huiyu Zhuang,Bei Lin,Dawo Liu,Zhenhua Hu,Juanjuan Liu,Jian Gao,Irina U Agoulnik

doi:10.1371/journal.pone.0068994

Abstract

ObjectiveThe main aims of this study were to explore the molecular structural relationship between Human epididymis protein 4 (HE4) and Lewis y antigen by determining their expression patterns and clinical significance in ovarian epithelial carcinoma.MethodsThe structural relationship between HE4 and Lewis y antigen was examined using immunoprecipitation and confocal laser scanning microscopy. HE4 and Lewis y were detected in tissues from malignant (53 cases), borderline (27 cases), benign (15 cases) and normal ovarian tissues (15 cases) using immunohistochemical analysis.ResultsHE4 was present in ovarian cancer, benign tumor tissues, ovarian carcinoma cells, and culture medium, and contained Lewis y antigen. Moreover, expression of Lewis y antigen in HE4 from ovarian cancer was higher than that from benign tumor (P<0.05). HE4 possibly exists as two protein isoforms, both containing Lewis y antigen. Our immunohistochemistry data revealed significantly higher positive expression rates of HE4 in malignant ovarian tissues, compared to benign tumor and normal tissue (P<0.05), similar to Lewis y antigen levels in ovarian cancer (P<0.05). Notably, tissues displaying marked expression of HE4 simultaneously expressed high levels of Lewis y antigen. A linear correlation between the expression patterns of HE4 and Lewis y antigen was evident. Consistently, double-labeling immunofluorescence experiments illustrated co-localization of HE4 and Lewis y antigen within the same area.ConclusionsHE4 contains Lewis y antigen. Our results further demonstrate a close correlation between the expression levels of the two antigens, which are significantly high in ovarian cancer.

Highlights

Among the tract malignancies in women, ovarian cancer causes the highest rates of mortality, and diagnosis at the early stages is inadequate
We investigated the correlation between Human epididymis protein 4 (HE4) and Lewis y antigen with the aid of co-immunoprecipitation and double-label immunofluorescence analyses
Our data indicate that HE4 possibly exists as two protein isoforms with a molecular weight difference of approximately 3 kDa

Summary

Introduction

Among the tract malignancies in women, ovarian cancer causes the highest rates of mortality, and diagnosis at the early stages is inadequate. No markers for ovarian cancer with high sensitivity and specificity are currently available to facilitate clinical diagnosis, staging and monitoring for therapeutic interventions. Recent research has disclosed the presence of overexpressed HE4 (human epididymis protein 4) in blood serum of ovarian cancer patients. Expression of human epididymis protein HE4 (WFDC2) in ovarian cancer was initially reported in 1999 [1], and subsequently defined as a biological marker of ovarian cancer in 2003. HE4 secreted by ovarian cancer cells was shown to be N-glycosylated [3] Several issues, such as the glycosylation status of HE4 in human blood serum, structure, association with the occurrence, development, invasion, migration and resistance of ovarian cancer, and the underlying mechanisms, remain to be established

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Conclusion