E6-Encoded by Cancer-Causing Human Papillomavirus Interacts with Aurora Kinase A To Promote HPV-Mediated Carcinogenesis.

Abstract

The expression of human papillomavirus (HPV) oncoproteins perturbed multiple cellular events of the host cells, leading to the formation of cancer phenotypes. Our current and previous studies indicated that Aurora kinase A (AurA), a mitotic regulator that is often aberrantly expressed in human cancers, is preferentially bound to E6-encoded by cancer-causing HPV. AurA is believed to be important for the proliferation and survival of HPV-positive cells. Nonetheless, the interaction between AurA and E6, and the mechanism of how this association is involved in carcinogenesis, have not been elucidated clearly. Hence, we performed a series of biochemical assays to characterize the AurA-E6 association and complex formation. We found the C-terminus of E6, upstream of the PDZ binding motif of E6, is important to forming the AurA-E6 complex in the nucleus. We also showed that the expression level of E6 corresponded positively with AurA expression. Meanwhile, the functional consequences of the AurA-E6 association to AurA kinase function and host cellular events were also delineated. Intriguingly, we revealed that AurA-E6 association regulated the expression of cyclin E and phosphor-Histone H3, which are involved in G1/S and mitotic phases of the cell cycle, respectively. Depletion of AurA also reduced the invasive ability of HPV-positive cells. AurA inhibition may not be sufficient to reduce the oncogenic potential exerted by E6. Altogether, our study unleashed the mechanism of how HPVE6 deploy AurA to promote cancer phenotypes, particularly through dysregulation of cell cycle checkpoints and suggests that the AurA-E6 complex possesses a therapeutic value. IMPORTANCE We unveiled the mechanism of how HPV employs Aurora kinase A (AurA) of host cells to exert its oncogenic capability synergistically. We systematically characterized the mode of interaction between E6-encoded by cancer-causing HPV and AurA. Then, we delineated the consequences of AurA-E6 complex formation on AurA kinase function and changes to cellular events at molecular levels. Using a cell-based approach, we unleashed that disruption of AurA-E6 association can halt cancer phenotype exhibited by HPV-positive cancer cells. Our findings are vital for the designing of state-of-the-art therapies for HPV-associated cancers.