Targeting the CK1α/CBX4 axis for metastasis in osteosarcoma

Osteosarcoma, an aggressive malignant cancer, has a high lung metastasis rate and lacks therapeutic target. Here, we reported that chromobox homolog 4 (CBX4) was overexpressed in osteosarcoma cell lines and tissues. CBX4 promoted metastasis by transcriptionally up-regulating Runx2 via the recruitment of GCN5 to the Runx2 promoter. The phosphorylation of CBX4 at T437 by casein kinase 1α (CK1α) facilitated its ubiquitination at both K178 and K280 and subsequent degradation by CHIP, and this phosphorylation of CBX4 could be reduced by TNFα. Consistently, CK1α suppressed cell migration and invasion through inhibition of CBX4. There was a reverse correlation between CK1α and CBX4 in osteosarcoma tissues, and CK1α was a valuable marker to predict clinical outcomes in osteosarcoma patients with metastasis. Pyrvinium pamoate (PP) as a selective activator of CK1α could inhibit osteosarcoma metastasis via the CK1α/CBX4 axis. Our findings indicate that targeting the CK1α/CBX4 axis may benefit osteosarcoma patients with metastasis.


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The hFOB1.19, U2OS, MG63, 143B, HOS and HEK293T embryonic kidney cells were obtained from the American Type Culture Collection (ATCC) , The ZOS and ZOS-M, syngeneic human osteosarcoma cell lines derived from a primary tumor and metastasis, respectively, from the same patient, Starting with U2OS osteosarcoma cell line, the MTX300-resistant variant was obtained by exposing the parental line in vitro to stepwise the increased MTX concentrations.
Each cell line used were authenticated in Guangzhou Cellcook Biotech. 1. PCR is amplified with STR Multi-amplification Kit (PowerPlexTM16HS System); 2. PCR products are assayed with 3100 DNA Analyzer (Applied Biosystems®). 3. Amplification of gene COX1 and electrophoresis are employed to survey the species of the sample.
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To prepare the cells for flow cytometry sorting, live cells were harvested, resuspended in phosphate-buffered saline (PBS) with 10% fetal bovine serum and filtered using a 40 #m cell strainer (BD Falcon, Franklin Lakes, NJ, USA