MicroRNA-200c modulates epithelial-to-mesenchymal transition (EMT) in human colorectal cancer metastasis.
OBJECTIVE
Distant metastasis is the major cause of cancer-related death in patients with colorectal cancer (CRC). Although the microRNA-200 (miR-200) family is a crucial inhibitor of epithelial-to-mesenchymal transition (EMT) in human cancer, the role of miR-200 members in the pathogenesis of metastatic CRC has not been investigated.


METHODS
Fifty-four pairs of primary CRC and corresponding matched liver metastasis tissue specimens were analysed for expression and methylation status of the miR-200 family members. Functional analysis of miR-200c overexpression was investigated in CRC cell lines, and cells were analysed for proliferation, invasion and migration. Expression of several miR-200c target genes (ZEB1, ETS1 and FLT1) and EMT markers (E-cadherin and vimentin) in CRC cell lines and tissue specimens was validated.


RESULTS
Liver metastasis tissues showed higher expression of miR-200c (primary CRC = 1.31 vs. liver metastasis = 1.59; p = 0.0014) and miR-141 (primary CRC = 0.14 vs. liver metastasis = 0.17; p = 0.0234) than did primary CRCs, which was significantly associated with hypomethylation of the promoter region of these miRNAs (primary CRC = 61.2% vs. liver metastasis = 46.7%; p < 0.0001). The invasive front in primary CRC tissues revealed low miR-200c expression by in situ hybridization analysis. Transfection of miR-200c precursors resulted in enhanced cell proliferation but reduced invasion and migration behaviours in CRC cell lines. Overexpression of miR-200c in CRC cell lines caused reduced expression of putative gene targets, and resulted in increased E-cadherin and reduced vimentin expression. The associations between miR-200c, target genes and EMT markers were validated in primary CRCs and matching liver metastasis tissues.


CONCLUSIONS
miR-200c plays an important role in mediating EMT and metastatic behaviour in the colon. Its expression is epigenetically regulated, and miR-200c may serve as a potential diagnostic marker and therapeutic target for patients with CRC.
Gastrointestinal Cancer Research Laboratory, Baylor Research Institute and Sammons Cancer Center, Baylor University Medical Center, Dallas, TX 75246, USA.
Keun
K
Hur
Yuji
Y
Toiyama
Masanobu
M
Takahashi
Francesc
F
Balaguer
Takeshi
T
Nagasaka
Junichi
J
Koike
Hiromichi
H
Hemmi
Minoru
M
Koi
C Richard
CR
Boland
Ajay
A
Goel
D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism*; D045744:Cell Line, Tumor / Q000378:metabolism; D049109:Cell Proliferation; D015179:Colorectal Neoplasms / Q000235:genetics / Q000473:pathology; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008113:Liver Neoplasms / Q000556:secondary; D008297:Male; D008745:Methylation; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D009367:Neoplasm Staging; D014162:Transfection / Q000379:methods; D014746:Vimentin / Q000378:metabolism*
D014408:Biomarkers, Tumor; D015820:Cadherins; C533896:MIRN200 microRNA, human; D035683:MicroRNAs; D014746:Vimentin