The deleted in oral cancer (DOC1 aka CDK2AP1) tumor suppressor gene is downregulated in oral squamous cell carcinoma by multiple micro-RNAs

Cyclin-Dependent Kinase 2 Associated Protein 1 (CDK2AP1; also known as deleted in oral cancer or DOC1) is a tumor suppressor gene known to play functional roles in both cell cycle regulation and in the epigenetic control of embryonic stem cell differentiation, the latter as a core subunit of the nucleosome remodeling and histone deacetylation (NuRD) complex. In the vast majority of oral squamous cell carcinomas (OSCC), expression of the CDK2AP1 protein is reduced or lost. Notwithstanding the latter (and the DOC1 acronym), mutations or deletions in its coding sequence are extremely rare. Accordingly, CDK2AP1 protein-deficient oral cancer cell lines express as much CDK2AP1 mRNA as proficient cell lines. Here, by combining in silico and in vitro approaches, and by taking advantage of patient-derived data in the analysis of loss of CDK2AP1 expression, we identified a set of micro-RNAs, namely miR-21-5p, miR-23b-3p, miR-26b-5p, miR-93-5p, and miR155-5p, which inhibit its translation in both cell lines and patient-derived OSCCs. Last, CDK2AP1 loss, as the result of miRNA expression, correlates with overall survival thus highlighting its clinical relevance of these processes for carcinomas of the oral cavity.