Relationship between SDC1 and cadherin signalling activation in cancer.

E-cadherin and SDC1 are markers of epithelial-to-mesenchymal transition (EMT) that can be used to assess tumour prognosis. SDC1 has different effects in various types of cancers. On the one hand, reduced expression of SDC1 can leads to advantage stages of some cancers, such as gastric and colorectal cancer. On the other hand, SDC1 overexpression can also promote the growth and proliferation of cancer cells in pancreatic and breast cancer. However, the function of SDC1 is influenced and regulated by many factors. Exfoliated extracellular domain HS chain can mediate the function of SDC1 and play an important role in the occurrence and development of cancer. SDC1 binds to various ligands and influences the growth and reproduction of cancer cells via the activation of Wnt, the long isoform of FLICE-inhibitory protein (FLIP long), vascular endothelial growth factor receptor (VEGFR), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and MAPK/c-Jun N-terminal kinase (JNK) and other pathways. Cadherins occur in several types, but this review focuses on classical cadherins. N-cadherin and P-cadherin are activated during tumour development, whereas E-cadherin is a tumour suppressor. The cellular signalling pathways involved in classical cadherins, such as Wnt and VEGFR pathways, are also related to SDC1. The activation of E-cadherin caused by SDC1 knockdown has also been observed. Despite this evidence, no articles regarding the relationship of SDC1 and cadherin activation have been published. This review summarises the expressions of these two molecules in different cancers and analyses their possible relationship to provide insights into future cancer research and clinical treatment.