RALBP1 regulates oral cancer cells via Akt and is a novel target of miR-148a-3p and miR-148b-3p

Background: Malignant tumors arising from the epithelium of the oral cavity are termed as squamous cell carcinomas (OSCC). The aim of the current work was to understand the role of an isoform of RAS-like protein (RAL), RALBP1, in mediating squamous cell tumorigenesis. The study also aims to understand epigenetic modifications of RALBP1 mediated through microRNA-148a/b-3p.

Methods: Biopsies of tumor and healthy tissues from 25 patients with OSCC were collected and subjected to RNA and protein extraction to confirm upregulation of RLBP1 in tumor tissues. Expression of RLBP1 was silenced in SCC-9, using shRNA, and HN6 was transfected with plasmid bearing genes for RLBP1 over expression. Tumorigenic traits such as increased glucose uptake, aerobic glycolysis, enhanced cellular survival, cell migration, and invasion were assessed. Probable, molecular machinery involved in the upregulation was also assessed using Western blots. Using Target Scan tool, the miRNAs targeting RLBP1 were identified. Rescue of phenotypes in presence of miRNAs were also evaluated.

Results: Over expression of RLBP1 was associated with increased glucose uptake and aerobic glycolysis mediated ATP synthesis. The cells divided at a faster rate with a higher rate of migration and invasion phenotype. miR-148a/b-3p were found to target RLBP1 and rescued RLBP1 mediated phenotype.

Conclusion: RLBP1 may mediate squamous cell tumorigenesis in oral cavity, independently of the RAS protein and through Akt. miR-148a/b-3p functions as a tumor suppressor by targeting RLBP1.