Sperm protein antigen 17 and Sperm flagellar 1 cancer testis antigens are expressed in a rare case of ciliated foregut cyst of the common hepatic duct

Introduction: Ciliated foregut cysts (CFCs) are frequently described in liver, pancreas and gallbladder and generally considered benign although one case of squamous cell metaplasia and five cases of squamous cell carcinoma arising from a ciliated hepatic foregut cyst have been reported. Here we explore two cancer-testis antigens (CTAs), Sperm protein antigen 17 (SPA17) and Sperm flagellar 1 (SPEF1) expression in a rare case of CFC of the common hepatic duct Materials and Methods: 3 µm-thick CFC sections were immunohistochemically treated with antibodies raised against human SPA17 or SPEF1. In silico Protein-Protein Interaction (PPI) network and differential protein expression were also investigated Results: Immunohistochemistry revealed SPA17 and SPEF1 in the cytoplasm of ciliated epithelium. SPA17, but not SPEF1, was also detected in cilia. The PPI networks demonstrated that other CTAs are significantly predicted functional partners with SPA17 and SPEF1. The differential protein expression demonstrated that SPA17 was higher in breast cancer, cholangiocarcinoma, liver hepatocellular carcinoma, uterine corpus endometrial carcinoma, gastric adenocarcinoma, cervical squamous cell carcinoma, bladder urothelial carcinoma. SPEF1 expression was higher in breast cancer, cholangiocarcinoma, uterine corpus endometrial carcinoma and kidney renal papillary cell carcinoma Conclusions: Our study suggests that further characterization of SPA17 and SPEF1 in patients with CFCs might provide significant insights to understand the mechanisms underlying their potential to malignant transformation.