MicroRNAs, which are endogenously expressed regulatory noncoding RNAs, have an 
altered expression in colorectal cancer. The aim of our study was to assess the 
relationship of miR-21 and miR-143 expression to the 
prognostic/clinicopathological features of colorectal carcinoma (CRC) and 
colorectal liver metastases (CLM). The estimation was performed in 46 paired 
(tumor and control) tissue samples of CRC. Further, we studied 30 tissue samples 
of CLM. MiR-21 and miR-143 expressions were quantified by using the quantitative 
reverse transcription polymerase chain reaction method. Relation of miR-21 and 
miR-143 expression to disease-free interval (DFI) (Wilcoxon; P = 0.0026 and P = 
0.0191, respectively) was recorded. There was shorter DFI in patients with a 
higher expression of miR-21 and, surprisingly, also in patients with a higher 
expression of miR-143, which is a putative tumor suppressor. There was a higher 
expression of miR-21 and lower expression of miR-143 in CRC tissue in comparison 
with adjacent normal colon tissue (P < 0.0001; P < 0.0001, respectively). 
Similarly, we observed a higher expression of miR-21 and a lower expression of 
miR-143 in CLM in comparison with normal colon tissue (P < 0.0001; P < 0.0001, 
respectively). Our results support the hypothesis about oncogenic function of 
miR-21 and show its relation to DFI. The role of miR-143 in carcinogenesis seems 
to be more complex.