microRNAs (miRNAs) are key posttranscriptional regulators of gene expression. In 
the present study, regulation of tumor-suppressor gene D-glucuronyl C5-epimerase 
(GLCE) by miRNA-218 was investigated. Significant downregulation of miRNA-218 
expression was shown in primary breast tumors. Exogenous 
miRNA-218/anti-miRNA-218 did not affect GLCE mRNA but regulated GLCE protein 
level in MCF7 breast carcinoma cells in vitro. Comparative analysis showed a 
positive correlation between miRNA-218 and GLCE mRNA, and negative correlation 
between miRNA-218 and GLCE protein levels in breast tissues and primary tumors 
in vivo, supporting a direct involvement of miRNA-218 in posttranscriptional 
regulation of GLCE in human breast tissue. A common scheme for the regulation of 
GLCE expression in normal and tumor breast tissues is suggested.