Human Placental Lactogen

Human placental lactogen (HPL) is a single chain polypeptide hormone secreted by syncytiotrophoblast (STB) in the chorion of placenta. It plays a crucial role in various activities such as participating in fetal development, regulating maternal metabolism, and promoting milk secretion. In clinical practice, HPL is mainly used for the diagnosis of placental site trophoblastic tumor (PSTT). It is diffusely strongly expressed in PSTT but locally weakly expressed in choriocarcinoma, which makes it become an important distinguishing indicator. Meanwhile, some research suggested that HPL in endometrium is positive in patients with intrauterine pregnancy miscarriage but negative in patients with ectopic pregnancy. In addition, HPL is found in some breast cancer, and it may be related to the lymph node metastasis of cancer cells, which is speculated that the binding of HPL and prolactin receptors in tumor can regulate the cytoskeleton and enhance migration ability. Some scholars also found the breast cancer with choriocarcinomatous features, which can react with HPL and human chorionic gonadotropin (HCG).