Abstract 4325: CX-4945 (Silmitasertib) induces cell death through impairment of lysosomal utilization in KRAS mutant cholangiocarcinoma cell lines

Abstract

Abstract Purpose: Macropinocytosis is a non-selective endocytosis that uptakes extracellular substances such as nutrients and macromolecules into the cells. In KRAS-driven cancer such as pancreatic ductal adenocarcinoma, the macropinocytosis and following lysosomal utilization are enhanced to overcome metabolic stress. In this study, we investigated the role of CK2 in micropinocytosis and the following metabolic process in the KRAS mutant CCA cell line. Materials and Methods: The BSA uptake indicating micropinocytosis was performed by flow cytometry using the HuCCT1, cholangiocarcinoma cell line harboring KRAS mutation. To validate macropinosome, the Rab7 and LAMP2 were labeled and analyzed via immunocytochemistry and Western blot. The CX-4945, CK2 inhibitor, was used to investigate the role of CK2 in micropinocytosis and following lysosomal metabolism. Results: The HuCCT1, a KRAS mutant CCA cell line, showed micropinocytosis. Although CX-4945, a CK2 inhibitor, induced morphological changes accompanied by accumulation of intracellular vacuoles and cell death rate, the level of micropinocytosis was not changed. The vacuoles accumulated in the cell were identified as late macropinosomes representing Rab7 before fusion with lysosomes. In addition, the CX-4945 suppressed LAMP2 expression following inhibition of the Akt-mTOR signaling pathway which interrupts mature macropinosome and lysosomal metabolic utilization. Conclusion: These results support the utilization of micropinocytosis as an energy source even in CCA cell line harboring KRAS mutation. The inhibition of CK2, the regulator of macropinosome maturation, by CX-4945, alters lysosome dependent metabolism and leads to cell death in KRAS mutant CCA cell lines. Citation Format: Chorong Kim, Da Sol Lee, Minwoo Han, Seonmin Lee, Kyu-pyo Kim, Changhoon Yoo. CX-4945 (Silmitasertib) induces cell death through impairment of lysosomal utilization in KRAS mutant cholangiocarcinoma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4325.