COPS5 regulates osteosarcoma progression by upregulating KHSRP to promote Per2 mRNA decay

Osteosarcoma (OS) is a common bone sarcoma that is often seen in children and adolescents. This study delves into the intricate regulatory network involving COP9 signalosome subunit 5 (COPS5), KH-type splicing regulatory protein (KHSRP), and Period circadian clock 2 (Per2) in the context of osteosarcoma cell malignant phenotype. CCK-8 assay was applied to assess cell proliferation. Wound healing or transwell assay was selected to evaluate cell migration or invasion. Apoptosis was determined employing flow cytometry assay. Co-IP and GST-pull down determined the interaction between COPS5 and KHSRP. The interaction relationship between KHSRP and Per2 mRNA was detected by RNA-pull down and RIP assays. We found that COPS5 knockdown repressed proliferation, migration, and invasion and facilitated apoptosis of OS cells. Knockdown of COPS5 also restrained the tumor growth in the nude mice tumor xenograft model. COPS5 interacted with KHSRP to maintain the protein stability of KHSRP. Furthermore, there was a binding relationship between KHSRP and Per2 mRNA. Besides, COPS5 promoted OS cell tumorigenesis by mediating the decay effect of KHSRP on Per2 mRNA. Collectively, COPS5 promoted the decay of Per2 mRNA via contacting and mediating KHSRP, thereby facilitating OS progression. Our study unveils COPS5 as a key modulator in OS.