B Subunit of Human Chorionic Gonadotropin Promotes Tumor Invasion and Predicts Poor Prognosis of Early-Stage Colorectal Cancer.

BACKGROUND/AIMS: It is well established that many non-trophoblastic tumors secrete HCG (human chorionic gonadotropin) and that such secretion is correlated with the poor prognosis of tumor patients. This study aims to analyze the correlation between ß-HCG expression and outcome of colorectal cancer (CRC) and understand its role in CRC pathology Methods: We detected the mRNA and protein expression of ß-HCG in human CRC tissues with RT-qPCR and immunohistochemistry, and we compared the clinical-pathological characteristics, prognosis and progression between the ß-HCG positive and negative groups. We also generated CRC cell lines with ß-HCG over-expression as well as ß-HCG stable knockout, and evaluated cell function and mechanism in vitro and in vivo. RESULTS: Fifty out of 136 CRC patients (37%) expressed ß-HCG at the invasive front. Clinical-pathological data showed that ß-HCG was positively correlated with Dukes staging (P=0.031) and lymph node metastasis (P=0.012). Survival analysis suggested that the patients with high expression of ß-HCG had poorer prognosis than those with low ß-HCG expression (P=0.0289). ß-HCG expression level was also positively correlated with tumor invasion in early-stage CRC patient tissues (P=0.0227). Additionally ß-HCG promoted the migration and invasion of CRC in vitro and in vivo but had no effect on the proliferation of tumor cells. CONCLUSION: Our study demonstrated that ß-HCG was ectopically expressed in the CRC patients and its high expression correlated with poor prognosis of early-stage CRC. Additionally it worked as an oncogene that promotes the migration and invasion of CRC by epithelial-mesenchymal transition (EMT).