title: Design of a PROTAC that antagonizes and destroys the cancer-forming X-protein of the hepatitis B virus.
abstract: The X-protein of the hepatitis B virus (HBV) is essential for virus infection and contributes to the development of HBV-induced hepatocellular carcinoma (HCC), a disease which causes more than one million deaths each year. Here we describe the design of a novel PROTAC (proteolysis targeting chimeric molecule) capable of simultaneously inducing the degradation of the X-protein, and antagonizing its function. The PROTAC was constructed by fusing the N-terminal oligomerization and C-terminal instability domains of the X-protein to each other, and rendering them cell-permeable by the inclusion of a polyarginine cell-penetrating peptide (CPP). It was predicted that the oligomerization domain would bind the X-protein, and that the instability domain would cause the X-protein to be targeted for proteasomal degradation. Addition of the PROTAC to HepG2 liver cancer cells, engineered to express full-length and C-terminally truncated forms of the X-protein, resulted in the degradation of both forms of the X-protein. A cell-permeable stand-alone form of the oligomerization domain was taken up by HepG2 cells, and acted as a dominant-negative inhibitor, causing inhibition of X-protein-induced apoptosis. In summary, the PROTAC described here induces the degradation of the X-protein, and antagonizes its function, and warrants investigation in a preclinical study for its ability to prevent or treat HBV infection and/or the development of HCC.
authors.affiliation: Department of Molecular Medicine & Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
authors.forename: Kristopher
authors.initials: K
authors.lastname: Montrose
authors.affiliation: Department of Molecular Medicine & Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand. Electronic address: gw.krissansen@auckland.ac.nz.
authors.forename: Geoffrey W
authors.initials: GW
authors.lastname: Krissansen
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis; D015195:Drug Design; D056945:Hep G2 Cells; D006801:Humans; D008969:Molecular Sequence Data; D009374:Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology*; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000494:pharmacology*; D011230:Precancerous Conditions / Q000378:metabolism*; D015534:Trans-Activators / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D009842:Oligopeptides; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein
keywords: Apoptosis; Cell-penetrating peptide; Hepatitis B virus; Proteolysis targeting chimeric molecule; X-protein