Non-canonical role of UCKL1 on ferroptosis defence in colorectal cancer

Abstract

Background: Pyrimidine nucleotides fuel the growth of colorectal cancer (CRC), making their associated proteins potential targets for cancer intervention. Uridine-Cytidine Kinase Like-1(UCKL1) is an enzyme involved in the pyrimidine salvage pathway. It is highly expressed in multiple cancers. But the function and underlying mechanism of UCKL1 in CRC are yet to study.

Methods: Large-scale genomic analysis was performed to search for potential CRC players related to pyrimidine metabolism. The function of UCKL1 in CRC were examined by RNA interference coupled with in vitro and in vivo assays. GSH/GSSG assay, NADP+ assay, ROS, and Lipid peroxidation assays were performed to check the function of UCKL1 in ferroptosis. Metabolomics analyses, RNA sequencing, western blotting, and rescue assays were done to reveal the underlying mechanisms of UCKL1. Xenograft mouse model was used to examine the therapeutic potential of UCKL1 as a target in combination with other ferroptosis inducers.

Findings: UCKL1 was identified to repress ferroptosis in CRC cells. It was highly expressed in CRC. It regulated CRC cells proliferation and migration. Downregulation of UCKL1 led to enhanced tumour lipid peroxidation. Intriguingly, UCKL1 reduction-mediated ferroptosis was not related to its role in catalyzing uridine monophosphate (UMP) and cytidine monophosphate (CMP) synthesis. Instead, UCKL1 stabilized Nrf2, which in turn promoted the expression of SLC7A11, a classical repressor of ferroptosis. Moreover, downregulation of UCKL1 sensitized CRC cells to GPX4 inhibitors in vitro and in vivo.

Interpretation: Our study demonstrates that UCKL1 plays a non-canonical role in repressing ferroptosis through a UCKL1-Nrf2-SLC7A11 axis in CRC cells. Combinatorial strategy in targeting ferroptosis by depletion of UCKL1 and application of GPX4 inhibitors may serve as a new effective method for CRC treatment.

Funding: This study was supported in part by fund from National Natural Science Foundation of China (Grant No. 31970674 to PY), by the Basic and Applied Basic Research Program of Guangdong Province (Grant No. 2023A1515030245 to KL), by the program of Guangdong Provincial Clinical Research Center for Digestive Diseases (2020B1111170004), and by National Key Clinical Discipline.

Keywords: Colorectal cancer (CRC); Ferroptosis; Nrf2; SLC7A11; UCKL1.