Peptide KRP Conjugated with Doxorubicin Exerts Anti-Tumor Activity by Regulating RPS6KA2 in Osteosarcoma

Abstract Objectives: Osteosarcoma (OS) is the most common primary solid malignant tumor of the bone in adolescents. Conventional treatment of OS by surgery and chemotherapy is not effective and the prognosis is poor. Our previous study demonstrated that a novel cell-penetrating peptide (KRP) that, coupled to doxorubicin (DOX), allowed specific tumor targeting. However, the underlying molecular mechanisms of the KRP-DOX antitumor effect were not completely elucidated. Therefore, the present work aimed to identify key candidate genes by integrated bioinformatics analysis. Methods: Differentially expressed genes (DEGs) were screened using the Network Analyst. The functions and pathway involvements of the DEGs were analyzed using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, respectively. The protein-protein interaction (PPI) network was used to identify hub genes. In addition, quantitative RT-PCR (qRT-PCR) and Western blotting were performed to assess the expression level of candidate biomarkers in OS cells after KRP-DOX treatment. Results: A total of 790 DEGs were identified. GO functional analysis and KEGG pathway analysis demonstrated that the DEGs were mostly enriched in the ribosome. DEGs were visualized by PPI networks. After treatment of OS cells with KRP-DOX, the downregulated ribosomal protein S6 kinase A2 (RPS6KA2) was found to be closely related to inhibition of OS proliferation. In agreement with the bioinformatics analysis, qRT-PCR and western blot results showed low expression of RPS6KA2 in osteosarcoma cells in the KRP-DOX treatment group.Conclusions: RPS6KA2 is significantly associated with the KRP-DOX anti-tumor effect and may serve as a candidate biomarker and therapeutic target for OS.