Gamma smooth muscle actin as a new potential marker of cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs) represent an important component of the cancer ecosystem, influencing the broad scale of biological properties of tumour cells, including the capacity for metastasis formation. An important CAF subpopulation, known as myCAFs, typically expresses α-smooth muscle actin. Transcriptomic analysis demonstrated that activated fibroblasts isolated from various pathological tissues also express the ACTG2 gene encoding γ-smooth muscle actin. This was further validated by immunocytochemistry. Using the scratch test in vitro, it was possible to demonstrate that γ-smooth muscle actin may be associated with the epithelial-mesenchymal transition, which was also shown by transcriptomic analysis. The presence of γ-smooth muscle actin-positive fibroblasts in histopathological sections of human tumours verified the expression of this protein as a new potential marker of CAFs.