Abstract LB046: Treatment of EGFR-mediated tumors via lysosome activity regulation
Authors: Kim Dohyang , Zhu Anlin , Hong Jaewoo 
Published: April 2024

Abstract
The lysosome is a membrane-enclosed organelle that is an essential part of the cell's digestive system. This organelle contains over 60 types of hydrolases that can break down biological polymers such as proteins, carbohydrates, lipids, and nucleic acids. These enzymes require an acidic pH for optimal function, which is achieved by using ATP hydrolysis to pump protons against their electrochemical gradient into the lysosome by the vacuolar H+ ATPase (V-ATPase). The biogenesis of lysosomes is known to be controlled by the coordination of the regulatory gene network and the lysosomal expression, which is governed by the nuclear translocation of transcription factor EB (TFEB). Lysosomes are an essential component of the inner membrane system and participate in numerous cell biological processes, such as macromolecular degradation, antigen presentation, intracellular pathogen destruction, plasma membrane repair, exosome release, cell adhesion/migration, and apoptosis. The primary function of lysosomes is to digest extracellular material that has been internalized by endocytosis and intracellular components that have been sequestered by autophagy. They recycle the unwanted cellular material as energy, providing a nutrient source for maintaining cellular homeostasis. Lysosomal activity affects the tumor microenvironment, making the tumor cells use energy more efficiently, and it is known to be increased compared to neighboring normal tissues. However, recent studies have shown that increased lysosomal activity can lead to downregulating Receptor tyrosine kinase (RTK) activity in cancer cells. RTK activity frequently occurs with mutations in EGFR in various human cancers. Thus, EGFR is currently a target for several cancer therapies. Recently, studies on EGFR-mediated tumors through lysosome regulation have been continuously conducted. According to our previous study, it has been found that lysosome inactivation suppresses the degradation of RKT, such as EGFR, and increases the expression of EGFR.EGFR is expressed in various human tumors, including gliomas and carcinomas of the lung, colon, head and neck, pancreas, breast, ovary, and kidney. Mutations, gene amplification, and protein overexpression of various pathway elements contribute to carcinogenesis and impact prognosis. Alterations within the EGFR signaling cascade, such as gene mutations, gene amplification, and protein overexpression, have been shown to contribute to colorectal carcinogenesis.[4]In this study, we will down-regulate the expression of EGFR by activating the lysosome in DLD-1, a colorectal cancer cell line. Lysosome was activated by overexpression of V-ATPase using the lentiviral system. In vitro experiments confirmed that the degradation of EGFR was actively performed in the lysosome-activated experimental group. It inhibited cancer cells' proliferation, survival, and differentiation. Targeting lysosomes may be a new approach to overcoming EGFR-mediated cancers.
Citation Format: Dohyang Kim, Anlin Zhu, Jaewoo Hong. Treatment of EGFR-mediated tumors via lysosome activity regulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB046.