Fuse-binding protein 1 is a target of the EZH2 inhibitor GSK343, in osteosarcoma cells.

Osteosarcoma is the primary cancer of leaf tissue and is regarded as a differentiation disease caused by genetic and epigenetic changes which interrupt the osteoblast differentiation from mesenchymal stem cells. Because of its high malignancy degree and rapid development, the morbidity and mortality are high. The enhancer of zeste homolog 2 (EZH2) is a catalytic subunit of polycomb repressive complex 2 (PRC2) and has been demonstrated to be involved in a variety of biological processes, such as cell proliferation and program cell death. EZH2 impairs gene expression by catalyzing the tri-methylation of histone H3 lysine 27 (H3K27me3) which controls gene transcription epigenetically. It is reported that EZH2 expression is higher in osteosarcoma than in osteoblastoma and the highest expression of EZH2 is found in osteosarcoma with metastasis. In the past few years, several potent inhibitors of EZH2 have been discovered, and GSK343 is one of them. In this study, we found that GSK343 inhibited osteosarcoma cell viability, restrained cell cycle transition and promoted programmed cell death. GSK343 not only inhibited the expression of EZH2 and its target, c-Myc and H3K27me3, but it also inhibited fuse binding protein 1 (FBP1) expression, another c-Myc regulator. Furthermore, we found that FBP1 physically interacts with EZH2. Based on these results, we believe that GSK343 is a potential molecule for osteosarcoma clinical treatment. Other than the inhibition on EZH2-c-Myc signal pathway, we postulate that the inhibition on FBP1-c-Myc signal pathway is another potential underlying mechanism with which GSK343 inhibits osteosarcoma cell viability.