1953P - The ATXN3-USP25-TRMT1 axis regulates tRNAm2,2G modification and promotes osimertinib resistance in lung cancer

Background

Osimertinib is an oral third-generation EGFR-TKI, which is recommended as the first-line treatment for patients with advanced non-small cell lung cancer with EGFR activation mutation. However, patients receiving osimertinib inevitably experience acquired drug resistance. Deubiquitinases (DUBs) play a crucial role in the occurrence and development of tumors. But, there is limited research on the relationship between osimertinib resistance and DUBs.

Methods

We constructed cell lines resistant to osimertinib, screened the high expression of DUBs in osimertinib-resistant cells, and found that ATXN3 was highly expressed in drug-resistant cells.CO-IP and IP-MS screened that ATXN3 interacted with USP25, and USP25 interacted with TRMT1. Ubiquitination and CHX experiments proved that ATXN3 stabilized USP25 through deubiquitination, and USP25 could regulate TRMT1 at the protein level. tRNA mass spectrometry results showed that TRMT1 could regulate the tRNAm2,2G modification level. By examining ROS levels and osimertinib resistance phenotypes, it was found that TRMT1 promotes osimertinib resistance by down-regulating intracellular ROS levels.

Results

ATXN3 promoted tumor cells resistance to osimertinib by stabilizing USP25. USP25 interacts with TRMT1 and regulate the expression of TRMT1 at the protein level. Mechanism studies have shown that TRMT1 regulating tRNAm2,2G modification can selectively enhance the translation efficiency of oxidoreductase and promote osimertinib resistance by reducing the level of intracellular ROS. In vitro and in vivo experiments showed that targeted USP25/TRMT1 could inhibit the growth of osimertinib-resistant cells and tumors. Clinical specimens confirmed that the expression of TRMT1 and USP25 in tumor tissues was up-regulated after osimertinib resistance.

Conclusions

In summary, we found that: 1) ATXN3-USP25-TRMT1 axis regulates ROS levels in tumor cells and promoting osimertinib resistance; 2) Targeting USP25/TRMT1 can increase the sensitivity of osimertinib-resistant cells to osimertinib and inhibit tumors growth. This study discovered a new mechanism of osimertinib resistance and provided a new treatment direction to overcome osimertinib resistance.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

National Health Commission Medical and Health Science and Technology Development Research Center.

Disclosure

All authors have declared no conflicts of interest.