CMAHP promotes metastasis by reducing ubiquitination of Snail and inducing angiogenesis via GM-CSF overexpression in gastric cancer.

Pseudogenes are generally considered "junk" DNA or "genomic fossils" generated during the evolution process that lack biological activity. However, accumulating reports indicate that pseudogenes have biological functions critical for cancer development. Experiments from the current study showed marked overexpression of the cytidine monophospho-N-acetylneuraminic acid hydroxylase pseudogene (CMAHP) in gastric cancer, which was associated with poor overall survival. However, the mechanisms underlying the activity of CMAHP in tumor development are largely unknown. Gene Set Enrichment Analysis (GSEA) revealed that CMAHP-correlated genes are significantly involved in epithelial-mesenchymal transition (EMT) and angiogenesis. Functional studies further confirmed that CMAHP mediates metastasis and angiogenesis in vitro and in vivo. Furthermore, CMAHP promoted cancer cell migration, invasion, and metastasis through Snail overexpression, which decreased ubiquitination mediated by NF-κB signaling. Angiogenesis is known to be induced by granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulation. CMAHP increased GM-CSF transactivation via promoting direct binding of c-Jun to the -1981/-1975 region of the GM-CSF promoter. Notably, CMAHP interacts with Histone H1.4 promoting histone acetylation to enhance c-Jun and RelA (p65) expression. Our collective findings provide novel evidence that CMAHP contributes to tumor progression and modulates metastasis and angiogenesis in gastric cancer.