RBM15 promotes COAD progression by regulating the m6A modification of TMC5.

Background: Colon adenocarcinoma (COAD) is a frequent digestive system malignancy with high mortality and poor prognosis. Transmembrane Channel-like 5 (TMC5) has been reported to play an oncological role in various cancers. However, the role and mechanism of TMC5 in COAD remain unclear.

Methods: TIMER and UALCAN databases analyzed the expression of TMC5 in COAD. TMC5, RNA-binding motif protein-15 (RBM15), E-cadherin, N-cadherin, Vimentin, Fibronectin, and RAD51 protein levels were determined using western blot. TMC5, RBM15, Ferritin heavy chain 1 (FTH1), and cystine/glutamate antiporter SLC7A11 (also commonly known as xCT) mRNA levels were examined using real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation, apoptosis, migration, and invasion were assessed using 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, and transwell assays. Caspase 3 activity, ROS level, Fe⁺ level, and glycolysis level were detected using commercial kits. Immunofluorescence assay analyzed 53BP1 and γH2AX foci. Role of TMC5 on COAD tumor growth was examined using xenograft tumor model in vivo. After SRAMP database analysis, interaction between RBM15 and TMC5 was verified using methylated RNA immunoprecipitation (MeRIP) and dual-luciferase reporter assay.

Results: TMC5 and RBM15 levels were significantly increased in COAD tissues and cells. Moreover, TMC5 silencing could inhibit COAD cell proliferation, migration, invasion, EMT, glycolysis, and induce apoptosis and ferroptosis in vitro, as well as repress tumor growth in vivo. At the molecular level, RBM15 could sustain RNA stability and TMC5 expression through regulating the m6Amodification.

Conclusion: RBM15 could facilitate COAD cell malignant behaviors at least by regulating the stability of TMC5 mRNA, providing a powerful and hopeful target for COAD treatment.