A Tumor Suppressor Gene Product, Platelet‐Derived Growth Factor Receptor‐Like Protein Controls Chondrocyte Proliferation and Differentiation

ABSTRACT The platelet‐derived growth factor receptor‐like (PDGFRL) gene is regarded as a tumor suppressor gene. However, nothing is known about the molecular function of PDGFRL. In this study, we initially clarified its function in chondrocytes. Among all cell lines examined, the PDGFRL mRNA level was the highest in chondrocytic HCS‐2/8 cells. Interestingly, the proliferation of chondrocytic HCS‐2/8 cells was promoted by PDGFRL overexpression, whereas that of the breast cancer‐derived MDA‐MB‐231 cells was inhibited. Of note, in PDGFRL‐overexpressing HCS‐2/8 cells, the expression of chondrocyte differentiation marker genes, SOX9, ACAN, COL2A1, COL10A1, and ALP, was decreased. Moreover, we confirmed the expression of PDGFRL mRNA in normal cartilage tissue and chondrocytes. Eventually, the expression of PDGFRL mRNA in condrocytes except in the case of hypertrophic chondrocytes was demonstrated in vivo and in vitro. These findings suggest that PDGFRL plays the different roles, depending upon cell types. Particularly, in chondrocytes, PDGFRL may play a new and important role which is distinct from the function previously reported. J. Cell. Biochem. 118: 4033–4044, 2017. © 2017 Wiley Periodicals, Inc. Platelet‐derived growth factor receptor‐like (PDGFRL) gene is regarded as a tumor suppressor gene, but little is known about the molecular function of PDGFRL. In this study, we report that PDGFRL overexpression in chondrocytic cells promoted cell proliferation and inhibited gene expression of chondrocyte differentiation markers. PDGFRL may play a new role which is distinct from the function previously reported.