Colorectal cancer (CRC) is a prevalent malignant tumor with a high death rate globally, whose metastasis is the primary cause of treatment failure and death. Recent studies indicate that epigenetic modifications (e.g., N6-methyladenosine m6A RNA modification) play a pivotal role in tumor progression. Specifically, methyltransferase-like 3 (METTL3)-mediated m6A modification influences cell death mechanisms and mitochondrial function by regulating downstream gene expression, thereby promoting CRC invasion and metastasis. However, its role in ferroptosis and metabolic regulation warrants further investigation. In this study, the expression levels of METTL3 and 5'-AMP-activated protein kinase catalytic subunit alpha-2 (PRKAA2) in CRC were analyzed using data from The Cancer Genome Atlas (TCGA)-COAD dataset and validated in CRC cells by quantitative real-time polymerase chain reaction (RT-qPCR) and Western blot. The results showed that METTL3 was highly expressed in both CRC tissues and cell lines. The results demonstrated that METTL3 overexpression significantly reduced the levels of core ferroptosis indicators (Fe2+, MDA, and cellular/mitochondrial ROS) and increased the mitochondrial membrane potential in HCT15 cells. Furthermore, Western blot analysis revealed that METTL3 overexpression upregulated the protein expression of GPx4, HSP60, and MFN2 in HCT15 cells. Transwell assays indicated that METTL3 overexpression enhanced the migration and invasion of HCT15 cells. PRKAA2 is downregulated in CRC tissues and cell lines. Overexpression of PRKAA2 reversed the inhibitory effects of METTL3 overexpression on ferroptosis and mitochondrial dysfunction and attenuated the migration and invasion capabilities of HCT15 cells. METTL3 overexpression increased the m6A modification level of PRKAA2, decreased its mRNA stability, and subsequently significantly inhibited the mRNA and protein expression of PRKAA2. Finally, a lung metastasis mouse model was established by tail vein injection of HCT15 cells. In vivo experiments showed that METTL3 overexpression promoted the formation of lung metastatic foci, increased the number of pulmonary nodules, reduced Fe2+, MDA, and ROS levels in lung tissues, and upregulated the expression of GPx4, HSP60, and MFN2. Conversely, PRKAA2 overexpression effectively reversed the in vivo effects of METTL3 overexpression and inhibited CRC lung metastasis. In conclusion, both in vivo and in vitro experiments demonstrate that METTL3 suppresses PRKAA2 expression by reducing its mRNA stability through m6A modification. This reveals a novel mechanism by which METTL3 targets PRKAA2 via m6A modification to regulate ferroptosis and mitochondrial function, thereby facilitating tumor metastasis in CRC from the perspective of intracellular molecular regulation.
Duan et al. (Wed,) studied this question.