ALKBH8-Mediated Codon-Specific Translation Promotes Colorectal Tumorigenesis

Reprogramming gene expression at the translational level drives intestinal tumorigenesis. Codon decoding during translation elongation relies on tRNA modifications, while their pathological relevance in colorectal cancer remains to be elucidated. Here, we show that AlkB homolog 8 (ALKBH8), a uridine 34 (U34) tRNA methyltransferase, is a direct target of Wnt/ß-catenin and is upregulated in colorectal cancer. Genetic ablation of ALKBH8 inhibits the development of intestinal tumors in Apcmin/+, AOM/DSS, and xenograft models. Loss of ALKBH8 induces ribosome pausing at adenine-ending codons, impairing the translation elongation of mRNAs enriched with these codons. Specifically, ALKBH8 regulates the translation of KRAS proto-oncogene in a codon-dependent manner. Rescue experiments demonstrate that the methyltransferase activity of ALKBH8 is required for its translation-promoting function. Together, our findings reveal ALKBH8-dependent mRNA translation as a critical mediator of intestinal tumorigenesis, underscoring its potential as a promising target for colorectal cancer therapy. Overall design: Examination of the translatome in HCT116 ALKBH8 knockout amd overexpressin cells compared to HCT116 WT cells using Ribo-Seq technology.Performed on intestinal tumor tissues from ApcMin/+ mice with or without Alkbh8 knockout to investigate the in vivo role of ALKBH8 in colorectal tumorigenesis. Single-cell RNA sequencing was conducted in the AOM/DSS-induced colitis-associated colorectal cancer model to compare cellular heterogeneity and transcriptional alterations in Alkbh8 knockout versus control mice.