MicroRNA-224 Induces G1/S Checkpoint Release in Liver Cancer.
Profound changes in microRNA (miR) expression levels are frequently found in liver cancers compared to the normal liver. In this study, we evaluate the expression of miR-224 in human HCC and CCA, as well as its downstream targets and affected pathways. We show that miR-224 is upregulated in a large cohort of human CCA, similar to its upregulation in human HCC. For the purpose of studying the roles of miR-224 in HCC and CCA, we enforced miR-224 expression in cells. mRNA arrays followed by Ingenuity Pathway Analysis (IPA)-identified putative molecules and pathways downstream of miR-224. Phenotypically, we report that enforced expression of miR-224 increases the growth rate of normal cholangiocytes, CCA cell lines, and HCC cell lines. In addition, we identified, in an unbiased fashion, that one of the major biologic processes affected by miR-224 is Gap1 (G1) to Synthesis (S) transition checkpoint release. We next identified p21, p15, and CCNE1 as downstream targets of miR-224 and confirmed the coordinated downregulation results in the increased phosphorylation of Retinoblastoma (Rb) with resulting G1/S checkpoint release. Our data suggest that miR-224 is a master regulator of cell cycle progression, and that its overexpression results in G1/S checkpoint release followed by accelerated cell growth.
Department of Gastroenterology, Wuxi People's Hospital Affiliated to Nanjing Medical University, Wuxi, Jiangsu 214002, China. wdf8025@163.com.
Fangmei
F
An
Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins Hospital, Baltimore, MD, 21205, USA. aolaru1@jhmi.edu.
Alexandru V
AV
Olaru
Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins Hospital, Baltimore, MD, 21205, USA. emezey@jhmi.edu.
Esteban
E
Mezey
Department of Infectious Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China. xieqingrjh@163.com.
Qing
Q
Xie
Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins Hospital, Baltimore, MD, 21205, USA. lli42@jhmi.edu.
Ling
L
Li
Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins Hospital, Baltimore, MD, 21205, USA. kpiontek@jhmi.edu.
Klaus B
KB
Piontek
Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins Hospital, Baltimore, MD, 21205, USA. fselaru1@jhmi.edu.|The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins Hospital, Baltimore, MD, 21287, USA. fselaru1@jhmi.edu.
Florin M
FM
Selaru
cell cycle; cholangiocarcinoma; miR-224