Tumor-Specific Therapies Targeting Antigen Presentation and Misregulated Proteolysis

The central tenant of therapeutic design for cancer is the ability to preferentially kill oncogenic cells over healthy cells. Paramount to this approach is an understanding of the biology of cancer and how oncogenesis rewires cells in unique and targetable ways. Presented in this thesis are chapters covering different ways to approach this challenge. In chapter 1, we demonstrate that covalent inhibitors that target the acquired cysteine of KRas G12C are able to behave as haptens and be used as a tag to recruit an immune response to cancer cells. Covalently modified KRas G12C undergoes antigen presentation, presenting inhibitor-modified peptides on the cell surface in MHC I complexes. The discovery of antibodies specific for these complexes enabled the recruitment of an immune response to these cells, providing a greater therapeutic potential than treatment with inhibitor alone. In chapter 2, we characterize misregulated proteolysis in breast cancer, showing that genetic and transcriptional profiles correlate with proteolytic activity and identify specific proteases that are upregulated in basal b breast cancers. Using a combination of biochemical techniques, we design and synthesize substrates specific for one of these proteases, Cathepsin B, and show that a prodrug of doxorubicin based on this Cathepsin B substrate is able to kill a basal b breast cancer cell line. In chapter 3, we review the use and applications of Multiplex Substrate Profiling by Mass Spectrometry, a technique developed in Craik lab to globally characterize proteolysis in complex samples