Syncytin-1 is a member of human endogenous retroviral W gene family (HERVW1). Known to be expressed in human placental trophoblast,
syncytin-1 protein mediates the fusion of cytotrophoblasts for the formation of syncytiotrophoblasts, the terminally differentiated form of trophoblast lineage. In addition, in vitro studies indicate that
syncytin-1 possessed nonfusogenic functions such as those for immune suppression, cell cycle regulation and anti-apoptotic activities. Overexpression of
syncytin-1 has been observed in various malignant tissues including breast, endometrial and
ovarian cancers. It was reported that
syncytin-1 gene expression is associated with dynamic changes of
DNA hypomethylation in the 5' LTR. In this study, applying the real-time PCR, Western blot analysis and immunohistochemistry methods, we demonstrate a constitutive expression of
syncytin-1 in normal pancreas tissues as well as normal tissues adjacent to
cancer lesions. Moreover, a reduced expression is found in the pancreatic
adenocarcinoma tissues. The expression levels of
syncytin-1 are not correlated with the stage, historical grade and gender, but inversely correlated with patients' age. Furthermore, COBRA and
bisulfite sequencing results indicated that the lower expression of
syncytin-1 is correlated with the hypermethylation of two CpG dinucleotides in the 5' LTR of
syncytin-1 gene. The nonfusogenic function of
syncytin-1 in normal pancreas as well as its role(s) in the pathogenesis and progression of
pancreatic cancers remains to be investigated. Identification of the two CpG dinucleotides around transcription start site as key epigenetic elements has provided valuable information for further studies on the epigenetic regulation of
syncytin-1 in
pancreatic cancer cells.