MST4 promotes MRC2 activity to drive osteosarcoma proliferation

ABSTRACT: Osteosarcoma is one of the most common types of orthopedic malignancies with an accelerated disease progression and poor prognosis.The purpose of this study was to further investigate the function of Serine/threonine protein kinase 4(MST4) in osteosarcoma and its underlying mechanisms. The expression level of MST4 in osteosarcoma tissues was determined by western blotting and immunohistochemical staining. Proliferation of osteosarcoma cells overexpressing MST4 in vitro was performed using CCK-8 assay, BrdU, clonogenic assay and flow cytometry.A xenograft mouse model was used to determine tumor growth after in vivo inoculation of SaOS-2 cells overexpressing MST4, and the expression of MST4 in tumor tissue was observed by PCR, WB, HE staining, immunohistochemistry.Ki67 was detected the proliferation of cells in tumor tissues. We divided SaOS-2 cells into an overexpression MST4 group and a vector expression group, and used liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based tandem mass-tagging (TMT) techniques to compare the protein expression differences between the two groups.The general characteristics of the significantly enriched proteins were determined by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and protein-protein interaction (PPI) analysis was performed using STRING.Proteins downstream of MST4 were verified with parallel reaction monitoring (PRM).Finally, the expression of candidate proteins was blocked by siRNA, and then the proliferation of osteosarcoma cells was observed. The results showed that MST4 was overexpressed in patients with worse prognosis and positively regulated the proliferation of osteosarcoma cells. The expression of MST4 promoted the growth of SaOS-2 cells in nude mice. A total of 545 proteins with markedly differential expression were identified and quantified. 25 proteins were further validated by PRM, among which CD109, KRT80 and MRC2 were significantly differentially expressed, and Immunohistochemistry revealed that the expression level of MRC2 was strongly positive (remarkably increased) in patients with worse prognosis (P<0.05). Moreover, knockdown of MRC2 using siRNAs indicated that the proliferation of osteosarcoma cells was inhibited. In conclusion, MST4 promotes MRC2 activity to drive osteosarcoma proliferation, which may be a potential therapeutic biomarker of osteosarcoma. Briefly, elimination of MRC2 expression could impair the positive regulation of osteosarcoma growth by MST4 and may improve the prognosis of patients with high MST4 expression by inhibiting osteosarcoma proliferation.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Xiaoyu Zhang  

LAB HEAD: Qiong Ma

PROVIDER: PXD034216 | Pride | 2026-10-26

REPOSITORIES: Pride