RNA mA methyltransferase TRMT61A promotes colorectal tumorigenesis by enhancing ONECUT2 mRNA stability and is a potential therapeutic target.

[BACKGROUND] The role of N1-methyladenosine (mA) in cancer is poorly understood. Here we explored the function of RNA methyltransferase TRNA methyltransferase 61A (TRMT61A) in colorectal cancer (CRC) and its potential as a therapeutic target.

[METHODS] RNA mA levels were assessed through liquid chromatography-mass spectrometry. The expression and clinical significance of TRMT61A were investigated across five human CRC cohorts. The function of TRMT61A was elucidated using CRC cell lines, patient-derived organoids, xenografts, and transgenic mouse models. Integrated analyses of mA-sequencing and RNA-sequencing revealed the underlying mechanisms of TRMT61A. A nanoparticle-based small interfering RNA (siRNA) delivery system and a specific inhibitor were developed to target TRMT61A. The efficacy and safety of targeting TRMT61A were assessed.

[RESULTS] Our research revealed a consistent increase in TRMT61A expression and total RNA mA levels within primary CRCs. High TRMT61A expression was associated with poor prognosis of CRC patients. Through CRISPR/Cas9 screenings, we identified TRMT61A as the most essential gene among mA regulators. Furthermore, we established that TRMT61A promoted CRC tumorigenesis and progression by enhancing the mRNA stability of critical targets in an mA-dependent manner. In particular, TRMT61A boosted the mRNA stability of one cut homeobox 2 (ONECUT2), which in turn triggered son of sevenless homolog 1 (SOS1) transcription, leading to the induction of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling in CRC. Notably, our study underscored the safety and substantial anti-CRC effects achievable by inhibiting TRMT61A using nanoparticle-encapsulated siTRMT61A or our newly discovered small molecule compound, pentagalloylglucose.

[CONCLUSIONS] Our study unveiled the tumor-promoting role of TRMT61A in CRC via the mA-ONECUT2-SOS1-MAPK/ERK pathway. Targeting TRMT61A showed promise as a therapeutic strategy for treating CRC.