The PRKN/METTL3/CLDN2 axis promotes colorectal cancer development through epigenetic mechanisms

Dysregulation of N6-methyladenosine (m6A) RNA methylation plays a crucial role in colorectal cancer (CRC) development. Despite the established oncogenic role of methyltransferase-like 3 (METTL3) in CRC, the mechanisms behind its tumor-promoting functions are not fully understood.

Functional impacts were assessed by measuring cell viability, invasion, colony formation, migration, apoptosis, and M2 macrophage polarization in vitro, as well as in vivo tumorigenicity. The interaction between METTL3 and claudin 2 (CLDN2) was validated via RNA immunoprecipitation and luciferase assays. The PRKN/METTL3 interaction was analyzed using immunoprecipitation (IP) and Co-IP experiments. The stability of mRNA and protein levels was examined by treating cells with actinomycin D or cycloheximide.

METTL3 and CLDN2 levels were upregulated in CRC samples and cells. Depletion of METTL3 or CLDN2 suppressed CRC cell proliferation, invasion, and migration, and inhibited M2 polarization of THP-1-derived macrophages. Mechanistically, METTL3 promoted m6A methylation and stability of CLDN2 mRNA in an insulin-like growth factor 2 binding protein 2 (IGF2BP2)-dependent manner. METTL3 silencing diminished CRC cell malignant phenotypes and M2 macrophage polarization via CLDN2 reduction. Moreover, PRKN enhanced METTL3 protein degradation through K63-linked polyubiquitination. The PRKN/METTL3 axis regulated malignant phenotypes of CRC cells. Additionally, METTL3 depletion repressed tumor growth and lung metastasis of xenografts in vivo via CLDN2.

Our work uncovers a previously unrecognized PRKN-METTL3-CLDN2 signaling network that orchestrates colorectal tumorigenesis, providing a compelling rationale for developing METTL3-targeted therapies against CRC.