MicroRNA-21 is overexpressed in human cholangiocarcinoma and regulates programmed cell death 4 and tissue inhibitor of metalloproteinase 3.
Cholangiocarcinomas (CCAs) are aggressive cancers, with high mortality and poor survival rates. Only radical surgery offers patients some hope of cure; however, most patients are not surgical candidates because of late diagnosis secondary to relatively poor accuracy of diagnostic means. MicroRNAs (miRs) are involved in every cancer examined, but they have not been evaluated in primary CCA. In this study, miR arrays were performed on five primary CCAs and five normal bile duct specimens (NBDs). Several miRs were dysregulated and miR-21 was overexpressed in CCAs. miR-21 differential expression in these 10 specimens was verified by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). To validate these findings, qRT-PCR for miR-21 was then performed on 18 additional primary CCAs and 12 normal liver specimens. MiR-21 was 95% sensitive and 100% specific in distinguishing between CCA and normal tissues, with an area under the receiver operating characteristic curve of 0.995. Inhibitors of miR-21 increased protein levels of programmed cell death 4 (PDCD4) and tissue inhibitor of metalloproteinases 3 (TIMP3). Notably, messenger RNA levels of TIMP3 were significantly lower in CCAs than in normals.


CONCLUSIONS
MiR-21 is overexpressed in human CCAs. Furthermore, miR-21 may be oncogenic, at least in part, by inhibiting PDCD4 and TIMP3. Finally, these data suggest that TIMP3 is a candidate tumor suppressor gene in the biliary tree.
Selaru
Florin M
FM
Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University, Baltimore, MD 21287, USA. fselaru1@jhmi.edu
Olaru
Alexandru V
AV
Kan
Takatsugu
T
David
Stefan
S
Cheng
Yulan
Y
Mori
Yuriko
Y
Yang
Jian
J
Paun
Bogdan
B
Jin
Zhe
Z
Agarwal
Rachana
R
Hamilton
James P
JP
Abraham
John
J
Georgiades
Christos
C
Alvarez
Hector
H
Vivekanandan
Perumal
P
Yu
Wayne
W
Maitra
Anirban
A
Torbenson
Michael
M
Thuluvath
Paul J
PJ
Gores
Gregory J
GJ
LaRusso
Nicholas F
NF
Hruban
Ralph
R
Meltzer
Stephen J
SJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D001650:Bile Duct Neoplasms / Q000378:metabolism*; D001653:Bile Ducts, Intrahepatic / Q000378:metabolism*; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000378:metabolism*
D051017:Apoptosis Regulatory Proteins; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; C114487:PDCD4 protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C088390:TIMP3 protein, human; D019717:Tissue Inhibitor of Metalloproteinase-3