Actin, Smooth Muscle

Alpha-smooth muscle actin (SMA) is one of the core components of smooth muscle cell cytoskeleton. It has multiple functions such as maintaining cell morphology, mediating cell migration, and participating in muscle contraction. In clinical practice, SMA is a specific diagnostic indicator for smooth muscle derived tumors, including angioleiomyoma, gastrointestinal leiomyoma, small intestinal leiomyosarcoma, etc. Moreover, some research found that SMA can be expressed in cancer associated fibroblasts (CAFs) in tumor microenvironment, and its high expression is closely related to the occurrence and development of liver cancer, gastric cancer, lung cancer, breast cancer, ovarian cancer, endometrial cancer and other cancers. This is because CAFs can promote epithelial-mesenchymal transition (EMT) and tumor angiogenesis by activating multiple signaling pathways, thereby accelerating cancer cell proliferation, invasion and metastasis. Therefore, the expression of SMA has important reference value for patient prognosis evaluation. In addition, SMA is a specific biomarker for myoepithelial cells, and its expression deletion is an important feature of invasive breast cancer.