BACKGROUND/AIMS: Epidermal growth factor receptor (EGFR) signaling has been implicated in the genesis and progression of cholangiocarcinoma. However, the characteristics of EGFR signaling in cholangiocarcinoma cells have not been characterized. Thus, we attempted to more fully characterize EGF/EGFR signaling in human cholangiocarcinoma cells. METHODS: EGFR phosphorylation and ubiquitination were evaluated using immunoblot techniques. EGFR internalization was analyzed by immunofluorescent staining of EGFR or by immunoblot analysis for biotinylated EGFR. Cell growth was assessed using the MTS assay. RESULTS: EGFR activation was sustained following EGF stimulation in cholangiocarcinoma cells as compared to hepatoma cells. This prolonged EGFR activation resulted in extended p42/44 MAPK activation in cholangiocarcinoma cells. Despite ubiquitination, EGFR activation-dependent internalization was defective in cholangiocarcinoma cells. Cell growth was increased in cholangiocarcinoma cells following EGF stimulation as compared to hepatoma cells, and this was significantly attenuated by EGFR kinase inhibitors. The EGFR kinase inhibitors also significantly decreased COX-2 expression in cholangiocarcinoma cells, while this was not evident in hepatoma cells. CONCLUSIONS: The results demonstrate that cholangiocarcinoma cells exhibit sustained EGFR activation due to defective receptor internalization. As EGFR kinase inhibitors effectively attenuated cellular growth, these agents may be therapeutically efficacious in human cholangiocarcinoma.
BACKGROUND/AIMS: Epidermal growth factor receptor (EGFR) signaling has been implicated in the genesis and progression of cholangiocarcinoma. However, the characteristics of EGFR signaling in cholangiocarcinoma cells have not been characterized. Thus, we attempted to more fully characterize EGF/EGFR signaling in humancholangiocarcinoma cells. METHODS:EGFR phosphorylation and ubiquitination were evaluated using immunoblot techniques. EGFR internalization was analyzed by immunofluorescent staining of EGFR or by immunoblot analysis for biotinylated EGFR. Cell growth was assessed using the MTS assay. RESULTS:EGFR activation was sustained following EGF stimulation in cholangiocarcinoma cells as compared to hepatoma cells. This prolonged EGFR activation resulted in extended p42/44 MAPK activation in cholangiocarcinoma cells. Despite ubiquitination, EGFR activation-dependent internalization was defective in cholangiocarcinoma cells. Cell growth was increased in cholangiocarcinoma cells following EGF stimulation as compared to hepatoma cells, and this was significantly attenuated by EGFR kinase inhibitors. The EGFR kinase inhibitors also significantly decreased COX-2 expression in cholangiocarcinoma cells, while this was not evident in hepatoma cells. CONCLUSIONS: The results demonstrate that cholangiocarcinoma cells exhibit sustained EGFR activation due to defective receptor internalization. As EGFR kinase inhibitors effectively attenuated cellular growth, these agents may be therapeutically efficacious in humancholangiocarcinoma.
Authors: Samira Benhamouche; Marcello Curto; Ichiko Saotome; Andrew B Gladden; Ching-Hui Liu; Marco Giovannini; Andrea I McClatchey Journal: Genes Dev Date: 2010-07-30 Impact factor: 11.361
Authors: Ling Xu; Martin Hausmann; Wolfgang Dietmaier; Silvia Kellermeier; Theresa Pesch; Manuela Stieber-Gunckel; Elisabeth Lippert; Frank Klebl; Gerhard Rogler Journal: BMC Cancer Date: 2010-06-18 Impact factor: 4.430
Authors: Ja-Yeon Kim; Hong Joo Kim; Jung Ho Park; Dong Il Park; Yong Kyun Cho; Chong Il Sohn; Woo Kyu Jeon; Byung Ik Kim; Dong Hoon Kim; Seoung Wan Chae; Jin Hee Sohn Journal: World J Gastroenterol Date: 2014-01-21 Impact factor: 5.742