Talk abstracts
Talk on Thursday 04:15-04:30pm submitted by Niyi Adelakun
Development of Nanobody-Based Protein Degraders Targeting HER2 through the Lysosomal Pathway
Niyi Adelakun (Department of Cancer Biology and Genetics, and Ohio State Biochemistry Program), Marie Butts (Department of Cancer Biology and Genetics), Nhat Le (Department of Cancer Biology and Genetics), Nam Chu
Abstract:
Human epidermal growth factor receptor 2 (HER2) is an oncogenic transmembrane protein that mediates crosstalk among members of the ErbB family and regulates key cellular processes, including proliferation, differentiation, and apoptosis. HER2 is highly amplified or overexpressed in aggressive breast and gastric cancers, making it a key target for cancer therapy. However, resistance to existing HER2-targeted therapies remains a major clinical challenge, underscoring the need for innovative treatment strategies. Targeted protein degradation (TPD) has emerged as a powerful approach for eliminating pathogenic proteins for both mechanistic studies and therapeutic applications. Proteolysis-targeting chimeras (PROTACs) are a class of TPD agents that co-opt the cellular degradation machinery to selectively eliminate disease-causing proteins. Here, we developed a new TPD platform, nanobody-based degraders (NDs), which combines the targeting specificity of nanobodies as proximity-directing agents. This method incorporates lysosomal-sorting motifs and cell-penetrating peptide to facilitate rapid lysosomal degradation of target proteins. In this study, we recombinantly engineered HER2-targeting ND constructs containing a C-terminal di-leucine lysosomal-sorting motif, and an N-terminal nona-arginine motif for cellular delivery. Using a HER2 kinase-domain targeting nanobody, we generated NDHER2, a nanobody-based degrader designed to direct HER2 through the lysosomal pathway. NDHER2 was evaluated in the HER2-overexpressing SKBR3 breast cancer cell line. Immunofluorescence and immunoblot analyses demonstrated efficient cellular delivery of NDHER2 and a significant reduction in HER2 levels relative to the control, supporting the effectiveness of this lysosome-directed degradation strategy. In addition, compared with the parent nanobody, NDHER2 showed significantly greater efficacy in suppressing HER2 downstream signaling and inhibiting tumor cell growth in vitro. By directly degrading HER2, this approach may help overcome mechanisms of therapeutic resistance and represent a promising strategy for the treatment of HER2-driven cancers.
Keywords: Targeted Protein Degradation, Nanobodies, HER2