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 β-HCG expression and outcome of colorectal cancer (CRC) and understand its role in CRC pathology Methods: We detected the mRNA and protein expression of β-HCG in human CRC tissues with RT-qPCR and immunohistochemistry, and we compared the clinical-pathological characteristics, prognosis and progression between the β-HCG positive and negative groups. We also generated CRC cell lines with β-HCG over-expression as well as β-HCG stable knockout, and evaluated cell function and mechanism in vitro and in vivo.

RESULTS: Fifty out of 136 CRC patients (37%) expressed β-HCG at the invasive front. Clinical-pathological data showed that β-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 β-HCG had poorer prognosis than those with low β-HCG expression (P=0.0289). β-HCG expression level was also positively correlated with tumor invasion in early-stage CRC patient tissues (P=0.0227). Additionally β-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 β-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).