TRIM40 interacts with ROCK1 directly and inhibits colorectal cancer cell proliferation through the c-Myc/p21 axis.

Background: Colorectal cancer (CRC) is the most common malignancy of the digestive tract, and to date, morbidity and mortality rates remain high. While existing therapeutic methods have achieved certain effective outcomes, there are still many problems in treating this disease. Therefore, it is still urgent to constantly find new therapeutic targets in CRC that could lead to new therapeutics.

Methods: Immunohistochemistry, Real-time PCR and Western Blot were employed to measure mRNA and protein levels of the target protein, respectively. The proliferation ability of CRC cells was evaluated using ATP assay, Soft agar assay, and nude mouse subcutaneous tumorigenesis assay. Protein Degradation Assay was conducted to determine protein degradation rate, while Ubiquitination assay was used to assess the ubiquitination modification level of target proteins. Immunoprecipitation assay was used to study protein interactions, and pull-down assay was employed to investigate direct interactions between proteins.

Results: TRIM40 was significantly down-regulated in CRC tissues, with its expression levels positively correlating with disease prognosis. Using both in vitro and in vivo approaches, it was demonstrated that TRIM40 could significantly inhibit the proliferation of CRC cells. Molecular mechanism studies showed that TRIM40 directly binds to and ubiquitinates ROCK1 protein, accelerating its degradation and subsequently reducing the stability of c-Myc protein. This cascade of events results in the release of transcriptional inhibition of p21 by c-Myc, leading to increased p21 expression and G0/G1 phase arrest in CRC cells.

Conclusion: This research suggests that TRIM40 could be a valuable therapeutic target for the treatment of CRC.