Expression and Purification of Hepatitis B Capsid Proteins for Cancer Therapeutics
Jeffrey S Bruni1, 2, Kilando Q Chambers2,3, and Stephen J Stray2
1Mississippi INBRE Research Scholar, Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson MS
2Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson MS
3Base Pair Program, University of Mississippi Medical Center and Murrah High School
Glioblastoma (GB) is a very common, aggressive malignant brain tumor that arises from astrocytes found in the adult brain. Although there are many types of treatment that are effective in the short term, the long-term prognosis still remains problematic. Since cancer cells arise from normal cells in the body, there needs to be a way of differentiating cancer cells from normal cells. Hepatitis B virus (HBV) capsid proteins (Cp) are capable of self-assembly, and have previously been shown to be able to bind cargo such as metal ions (SJ Stray, P Ceres, and A Zlotnick, Biochemistry 43: 9989-98), and thus have the potential to allow them to become a type of “shipping envelope” by assembling a virus-like particle (VLP) that can be used to package toxic particles to deliver them to GB cells. There are two forms of the HBV Cp that are under study: the 149 amino acid assembly domain (Cp149), and the 183 amino acid full-length sequence that includes the assembly domain and the sequences responsible for the interaction with RNA (Cp183). We have introduced the RGD peptide sequence into both Cp!49 and Cp183 in the hope that this will allow more specific targeting of GB cells. Both sequences are expected to be able to self-assemble, and be able to deliver toxic cargo such as platinum (Cp149) or RNA encoding toxic products (Cp183). We will evaluate different methods for expressing and purifying these Cp proteins.