Synaptophysin

Synaptophysin (Syn) is a calcium binding glycoprotein in neurons, mainly existing in the Synaptic vesicle membrane. It participates in the packaging, storage, and release of neurotransmitters, so it is a core regulatory factor for neural signal transmission and Synaptic plasticity maintenance. Some research found that Syn is highly expressed in neuroendocrine cells and neuroendocrine neoplasms (NENs), so it is often used in combination with CgA for differential diagnosis of various NENs such as gastro-entero-pancreatic NEN, small cell lung cancer, and pituitary adenoma, and the addition of Ki-67 can distinguish between neuroendocrine tumor (NET) and neuroendocrine cancer (NEC). Meanwhile, the combination of Syn with GFAP, NeuN, and Olig2 plays a significant role in the differential diagnosis of central neurocytoma. In addition, the negative expression of Syn is considered as an independent risk factor for poor prognosis in non-small cell lung cancer patients, this may be because its inhibitory effect on epithelial-mesenchymal transition (EMT) is ineffective.