An oncoprotein CREPT functions as a co-factor in MYC-driven transformation and tumor growth.

Understanding the mechanisms behind MYC-driven oncogenic transformation could pave the way for identifying novel drug targets. This study explored the role of CREPT in MYC-induced malignancy by generating MYC-transformed mouse embryonic fibroblasts (MEFs) with conditional CREPT deletion. Our results demonstrated that the loss of CREPT significantly impaired MYC-induced colony formation and cell proliferation, indicating that CREPT is essential for the malignant transformation of MEFs. Reintroducing CREPT in CREPT-deficient cells restored malignant properties. Furthermore, CREPT overexpression alone enhanced colony formation upon MYC induction but was insufficient to induce transformation without MYC, suggesting a cooperative interaction between CREPT and MYC in malignant transformation. CREPT deletion resulted in delayed cell cycle progression during the G2/M and S phases. CREPT enhanced the expression of MYC target genes by directly interacting with MYC through the CID domain of CREPT and the PEST domain of MYC. Arginine 34 of CREPT was identified as a critical residue for the interaction with MYC, and its mutation lost the ability of CREPT to promote MYC-driven colony formation and tumor growth in colorectal cancer models. Additionally, CREPT facilitated the recruitment of RNA Polymerase II to MYC-binding promoters, promoting transcriptional initiation of MYC-targeted genes. Our study also revealed a strong correlation between CREPT and MYC expression in various human cancers, particularly in colorectal cancer, where their interaction appears to play a significant role in tumorigenesis. These findings suggest that the CREPT-MYC interaction is crucial for the progression of MYC-driven cancers and presents a potential target for therapeutic intervention.