The purpose of this study was to identify
microRNAs (
miRNAs) involved in the pathology of
colorectal cancer (CRC) liver
metastasis and investigate their underlying mechanisms. A total of 39
miRNAs were identified to be differentially expressed between 16 primary CRC tissues with liver
metastases and 16 CRC tissues without liver
metastases from 32 patients by Affymetric
miRNA microarrays. A panel of eight
miRNAs were confirmed to be significantly and differentially expressed between CRC tissues with and without liver
metastases through quantitative reverse-transcription polymerase chain reaction (RT-PCR) analysis in the 32 patients. In a validated cohort of 99 CRC patients (44 with and 55 without liver
metastases), only miR-214 was validated to be significantly down-regulated in CRC with liver
metastases, which was associated with an unfavorable prognosis. Ectopic expression of miR-214 suppressed proliferation, migration, and invasion in vitro,
tumor growth and liver
metastasis in an in vivo xenograft mouse model, whereas miR-214 knockdown promoted proliferation, migration, and invasion in CRC cell lines. Further studies indicated that
fibroblast growth factor receptor 1 (FGFR1) was a potential target of miR-214. Restoring miR-214 expression in CRC cells decreased endogenous FGFR1
messenger RNA (
mRNA) and
protein levels. FGFR1 knockdown mimicked the
tumor suppressive effect of miR-214 on CRC cells, while reintroduction of FGFR1 abolished the
tumor suppressive effect of miR-214 on CRC cells. Moreover, miR-214 expression levels were inversely correlated with FGFR1 in CRC patients.
CONCLUSION: Down-regulation of miR-214 expression was correlated with increased FGFR1 expression levels, which may contribute to increased CRC liver
metastasis. miR-214 may serve as a potential marker to predict survival, and the miR-214-FGFR1 axis may be a therapeutic target in CRC patients.