Abstract
Chemoresistance is one main cause of failure in colorectal cancer (CRC) treatment. The role of transcription factor Ras-responsive element binding protein 1 (RREB1) remains unclarified in CRC chemoresistance. Herein, we reveal that RREB1 functions as an oncogene to promote cell proliferation and 5-fluorouracil (5-FU) chemoresistance in CRC, and SUMOylation is required for RREB1 to exert its oncogenic role in CRC. RREB1 induced cell cycle arrest at the S-phase and a decreased apoptosis rate under 5-FU exposure. Mechanistically, the interaction of RREB1 with lysine demethylase 1A (KDM1A) elevated expression of 5-FU targeting proteins thymidylate synthase (TS) and thymidine kinase (TK1) to maintain the nucleotide pool balance under 5-FU treatment, and enhanced activation of Chk1-mediated DNA damage response (DDR) pathway. The deSUMOylation of RREB1 resulted in a reduced interaction of RREB1 with KDM1A, contributing to a downregulation of TS expression and a less activation of DDR pathway. Moreover, KDM1A knockdown improved the DNA damage and reduced RREB1-mediated resistance to 5-FU. These findings provide new insights into RREB1-mediated chemotherapy responses in CRC and indicate RREB1 is a potential target for overcoming 5-FU resistance.