MCTS1 enhances the proliferation of laryngeal squamous cell carcinoma via promoting OTUD6B-1 mediated LIN28B deubiquitination

The aberrant upregulation of MCTS1 Re-Initiation and Release Factor (also known as Malignant T-cell-amplified sequence 1, MCTS1) can promote laryngeal squamous cell carcinoma (LSCC). It might act as a binding partner of multiple proteins. In this study, we further explored the expression of potential interaction between MCTS1 and OTU domain-containing protein 6B (OTUD6B) and its influence on the ubiquitination and degradation of OTUD6B's substrate in LSCC. LSCC cell lines AMC–HN–8 and TU177 were utilized for assessing protein-protein interaction, protein degradation and tumor growth in vitro and in vivo. The results showed that MCTS1 interacts with OUTD6B isoform 1 (OTUD6B-1) in the cell lines. Higher OTUD6B-1 expression is associated with significantly shorter progression-free interval in LSCC patients. OTUD6B positively modulated the expression of cyclin D1, cyclin E1 and c-Myc and LSCC cell proliferation in vitro and in vivo. MCTS1 negatively modulated the degradation of LIN28B in G1/S cells, via enhancing OTUD6B-mediated cleaving of K48-branched ubiquitin chains from LIN28B. OTUD6B or LIN28B shRNA weakened MCTS1 overexpression-induced cyclin D1 and c-Myc protein expression and LSCC cell proliferation. In summary, this study revealed that MCTS1 could enhance LSCC proliferation partially via the OTUD6B-LIN28B axis.