METTL14-Mediated RPL13A Expression Regulates Apoptosis and Invasion of Osteosarcoma via the PTEN/PI3K/AKT Signaling Pathway.

Osteosarcoma (OS) is a highly aggressive mesenchymal bone tumor with a dismal prognosis, and its underlying molecular mechanisms remain elusive. Ribosomal protein L13a (RPL13a) contributes to tumorigenesis, while methyltransferase-like 14 (METTL14), a core m6A methyltransferase, modulates OS progression via epigenetic regulation. Our prior work identified the PTEN/PI3K/AKT pathway as a key OS regulator. This study aimed to clarify the regulatory interplay among METTL14, RPL13a and PTEN/PI3K/AKT in OS, and verify that METTL14 mediates RPL13a m6A modification to regulate PTEN/PI3K/AKT signaling, affecting OS cell proliferation, apoptosis, migration and invasion. METTL14, RPL13a and m6A levels were detected in OS cell lines (U2OS, HOS, MG-63) and normal osteoblast hFOB1.19 cells. RPL13a knockdown, PTEN overexpression and METTL14 overexpression models were established in U2OS/HOS cells. M6A-RIP-qPCR and MeRIP assays confirmed RPL13a m6A modification, with functional (CCK-8, flow cytometry, wound healing, Transwell) and molecular (RT-qPCR, Western blotting) assays performed in triplicate replicates. METTL14 and RPL13a were upregulated in U2OS/HOS cells versus hFOB1.19 (p < 0.05). METTL14 overexpression elevated RPL13a m6A modification by ~1.8-fold (p < 0.05); si-RPL13a reduced RPL13a mRNA by > 60% (p < 0.05). RPL13a knockdown promoted apoptosis, inhibited proliferation/migration/invasion, downregulated PTEN and activated PI3K/AKT signaling, partially reversed by PTEN overexpression. METTL14 overexpression upregulated RPL13a/PTEN and suppressed PI3K/AKT activation, abolished by RPL13a knockdown. METTL14 appears to mediate the m6A methylation modification of RPL13a mRNA. Downregulation of RPL13a is associated with reduced PTEN and activated PTEN/PI3K/AKT signaling, which may ultimately contribute to suppressed osteosarcoma cell proliferation, migration, and invasion while promoting apoptosis.