MicroRNA-21 acts as an oncomir through multiple targets in human hepatocellular carcinoma.
OBJECTIVE
MicroRNA-21 negatively regulates several targets, thereby affecting tumorigenesis. However, its mechanism of action in human hepatocellular carcinoma is poorly understood, and no direct evidence has shown a correlation between microRNA-21 function and phenotype. In this study, we investigate the function of microRNA-21 as a potent oncomir and probe the relationship between microRNA-21, its targets, and phenotypic alterations.


METHODS
We designed a set of rescue experiments using different combinations of anti-microRNA-21, siRNA, and a negative control to modulate the protein level of microRNA-21 targets and resulting phenotypic alterations. MicroRNA-21 was suppressed using anti-microRNA-21 to further uncover its effect on several critical signaling pathways.


RESULTS
We demonstrate that hepatocellular carcinoma is characterized by elevated levels of microRNA-21 and marked reductions of PTEN, PDCD4, and RECK expression. Silencing of PTEN and PDCD4 to prevent their induction by anti-microRNA-21 treatment led to decreased apoptosis and increased invasion, while silencing of RECK only led to increased invasion. Moreover, knockdown of microRNA-21 resulted in alterations of the Akt signaling pathway, the expression of p21 and MMP families, which are associated with apoptosis, and the cell cycle or invasiveness of cancer cells.


CONCLUSIONS
MicroRNA-21 simultaneously regulates multiple programs that enhance cell proliferation, apoptosis or tumor invasiveness by targeting PTEN, PDCD4, and RECK in hepatocellular carcinomas. Targeting of microRNA-21 is sufficient to limit tumor cell proliferation and invasion in a manner that is likely to involve associated changes in multiple targets, suggesting that suppression of microRNA-21 may be a novel approach for the treatment of hepatocellular carcinoma.
Liu
Changzheng
C
National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College (PUMC), Department of Biochemistry, Beijing, PR China.
Yu
Jia
J
Yu
Shuangni
S
Lavker
Robert M
RM
Cai
Lei
L
Liu
Wei
W
Yang
Kegong
K
He
Xiaodong
X
Chen
Songsen
S
D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D058851:GPI-Linked Proteins; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D008954:Models, Biological; D009361:Neoplasm Invasiveness; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D058851:GPI-Linked Proteins; C524940:MIRN21 microRNA, human; D008562:Membrane Glycoproteins; D035683:MicroRNAs; C114487:PDCD4 protein, human; C115460:RECK protein, human; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human