Silencing GDI2 inhibits proliferation, migration and invasion of colorectal cancer through activation of p53 signaling pathway.

Objective: To investigate the effect of silencing GDP dissociation inhibitor 2 (GDI2) on colorectal cancer development and possible mechanisms based on transcriptomic analysis.

Methods: The differences in the expression levels of GDI2 in normal colorectal tissues and tumor tissues of colorectal cancer (CRC) patients were detected. The correlation of GDI2 expression levels with survival and clinical characteristics of CRC patients was analyzed. The effects of GDI2 expression levels on the biological functions of CRC cells were examined by CCK-8 assay, plate clone formation assay, wound healing assay, and Transwell assay. The effect of GDI2 on the proliferation and growth of xenograft tumors was investigated by a xenograft tumor model of CRC in nude mice. Based on transcriptomics, we explored the possible mechanisms and associated pathways of the effect of silencing GDI2 on CRC cells. Cellular experiments and Western blot assays were performed to verify the potential mechanisms and related pathway of GDI2 action on CRC.

Results: The expression levels of GDI2 in CRC tissues and cells were higher than those in normal tissues and cells. The expression level of GDI2 correlated with clinical characteristics such as lymphatic metastasis, tumor stage, tumor volume, and lymphocyte count. Silencing of GDI2 reduced the proliferative activity and migration and invasion ability of CRC cells, as well as inhibited the proliferation of CRC xenograft tumors. The differentially expressed genes were significantly enriched in biological processes such as cell cycle arrest and the p53 signaling pathway after GDI2 silencing. The percentage of G0/G1 phase cells in CRC cells was increased after silencing GDI2 as verified by flow cytometry. RAB5A was highly associated with the p53 pathway and could interact with TP53 via the ZFYVE20 protein. The mutual binding between GDI2 protein and RAB5A protein was verified by immunoprecipitation assay. Silencing GDI2 while overexpressing RAB5A reversed the reduced proliferation, migration, and invasion ability as well as cell cycle arrest of CRC cells. Meanwhile, the addition of p53 signaling pathway inhibitor Pifithrin-α (PFT-α) also reversed the biological effects of silencing GDI2 on CRC cells. The p-p21 and p-p53 protein expression levels were significantly greater in the sh-GDI2 group than in the sh-NC group. However, the p-p21 and p-p53 protein expression levels were reduced after silencing GDI2 while overexpressing RAB5A.

Conclusion: Silencing GDI2 activates the p53 signaling pathway by regulating RAB5A expression levels, which in turn induces cell cycle arrest and ultimately affects the proliferative activity, migration, and invasive ability of CRC cells.