The function of S100A4 in pulmonary disease: A review

S100 protein family, which represents 25 relatively small calcium binding proteins, is involved in many intracellular and/or extracellular processes, including differentiation, apoptosis, migration/invasion, Ca2+ homeostasis, inflammation, and tissue repair. As an important member, S100A4 was reported to have an abnormal expression in several lung diseases, such as lung cancer, pulmonary hypertension, idiopathic pulmonary fibrosis (IPF), etc. For example, in lung cancer, S100A4 was demonstrated to be associated to metastatic tumor progression and epithelial to mesenchymal transition (EMT). In IPF, S100A4 was considered as a promising serum biomarker predicting disease progression. Various studies in recent years focused on the S100A4 function in lung diseases, showing researchers' interests on this protein. It is necessary to focuses on relative studies, and make a comprehensive understanding of S100A4 in common pulmonary diseases. By doing this, this paper provides a review of the evidence for S100A4 in lung cancer, chronic obstructive pulmonary disease (COPD), asthma, IPF and pulmonary hypertension.