Abstract: Objective To explore the functionalternation of human cholangiocarcinoma cell line HUCCA-1 by silencing Gab1 expression; to detect its effect on PI3KCA and Akt1 expression at protein and mRNA levels and to explore the roleof Gab1， PI3KCA and Akt1 expressions in the malignant behavior of cholangiocarcinoma. Methods Gab1 siRNA was trans⁃fected into cholangiocarcinoma cell line HUCCA-1. Proliferation, apoptosis, migration/ invasion of cells were examined byMTT, flow cytometry and Transwell assay respectively after transfection. PI3KCA and Akt1 expressions were detected by Western blotting and qPCR. Results Transfection efficiency was satisfactory and reaches 65%～70%； PI3KCA and Akt1 expressions were down- regulated at both protein and mRNA levels upon silencing of Gab1. Meanwhile, proliferations of HUCCA-1 cells were inhibited (P < 0.01） ;apoptosis rate increases（P < 0.05）; and migration and invasion were both inhibited upon Gab1 silencing（P < 0.05） . Conclusion The proliferation, migration and invasion are all inhibited while apoptosis is attenuated after Gab1 was down-regulated by Gab1 siRNA transfection. PI3KCA and Akt1 expressions are up-regulated
with down-regulation of Gab1. Therefore, Gab1 may enhance the maglinant behavior of cholangiocarcinoma cells through upregulating PI3KCA and Akt1 expression and it can be used as a candidate for cholangiocarcinoma therapy.

Key words: cholangiocarcinoma, proliferation, apoptosis, Gab1, HUCCA-1, PI3K/Akt pathway