PT  - JOURNAL ARTICLE
AU  - LEE, DA SOL
AU  - HAN, MIN WOO
AU  - KANG, YONGHYUN
AU  - KIM, CHORONG
AU  - LEE, SEONMIN
AU  - KIM, KYU-PYO
AU  - YOO, CHANGHOON
TI  - CX-4945 (Silmitasertib) Induces Cell Death by Impairing Lysosomal Utilization in <em>KRAS</em> Mutant Cholangiocarcinoma Cell Lines
AID  - 10.21873/anticanres.16996
DP  - 2024 May 01
TA  - Anticancer Research
PG  - 1939--1946
VI  - 44
IP  - 5
4099  - http://ar.iiarjournals.org/content/44/5/1939.short
4100  - http://ar.iiarjournals.org/content/44/5/1939.full
SO  - Anticancer Res2024 May 01; 44
AB  - Background/Aim: Macropinocytosis is a non-selective form of endocytosis that facilitates the uptake of extracellular substances, such as nutrients and macromolecules, into the cells. In KRAS-driven cancers, including pancreatic ductal adenocarcinoma, macropinocytosis and subsequent lysosomal utilization are known to be enhanced to overcome metabolic stress. In this study, we investigated the role of Casein Kinase 2 (CK2) inhibition in macropinocytosis and subsequent metabolic processes in KRAS mutant cholangiocarcinoma (CCA) cell lines. Materials and Methods: The bovine serum albumin (BSA) uptake indicating macropinocytosis was performed by flow cytometry using the HuCCT1 KRAS mutant CCA cell line. To validate macropinosome, the Rab7 and LAMP2 were labeled and analyzed via immunocytochemistry and western blot. The CX-4945 (Silmitasertib), CK2 inhibitor, was used to investigate the role of CK2 in macropinocytosis and subsequent lysosomal metabolism. Results: The TFK-1, a KRAS wild-type CCA cell line, showed only apoptotic morphological changes. However, the HuCCT1 cell line showed macropinocytosis. Although CX-4945 induced morphological changes accompanied by the accumulation of intracellular vacuoles and cell death, the level of macropinocytosis did not change. These intracellular vacuoles were identified as late macropinosomes, representing Rab7+ vesicles before fusion with lysosomes. In addition, CX-4945 suppressed LAMP2 expression following the inhibition of the Akt-mTOR signaling pathway, which interrupts mature macropinosome and lysosomal metabolic utilization. Conclusion: Macropinocytosis is used as an energy source in the KRAS mutant CCA cell line HuCCT1. The inhibition of CK2 by CX-4945 leads to cell death in HuCCT1 cells through alteration of the lysosome-dependent metabolism.