Abstract
ObjectiveMetastasis is the major cause of death in colorectal cancer patients. Expression of certain miRNAs in the primary tumors has been shown to be associated with progression of colorectal cancer and the initiation of metastasis. In this study, we compared miRNA expression in primary colorectal cancer and corresponding liver metastases in order to get an idea of the oncogenic importance of the miRNAs in established metastases.MethodsWe analyzed the expression of miRNA-21, miRNA-31 and miRNA-373 in corresponding formalin-fixed paraffin-embedded (FFPE) tissue samples of primary colorectal cancer, liver metastasis and healthy tissues of 29 patients by quantitative real-time PCR.ResultsAll three miRNAs were significantly up-regulated in the primary tumor tissues as compared to healthy colon mucosa of the respective patients (p < 0.01). MiRNA-21 and miRNA-31 were also higher expressed in liver metastases as compared to healthy liver tissues (p < 0.01). No significant difference of expression of miRNA-31 and miRNA-373 was observed between primary tumors and metastases. Of note, miRNA-21 expression was significantly reduced in liver metastases as compared to the primary colorectal tumors (p < 0.01).ConclusionIn the context of previous studies demonstrating increased miRNA-21 expression in metastatic primary tumors, our findings raise the question whether miRNA-21 might be involved in the initiation but not in the perpetuation and growth of metastases.
Highlights
Colorectal cancer (CRC) is the third most frequent cancer in women and men, respectively [1]
We analyzed the expression of miRNA-21, miRNA-31 and miRNA-373 in corresponding formalin-fixed paraffin-embedded (FFPE) tissue samples of primary colorectal cancer, liver metastasis and healthy tissues of 29 patients by quantitative real-time PCR
MiRNA-21 expression was significantly reduced in liver metastases as compared to the primary colorectal tumors (p < 0.01)
Summary
Colorectal cancer (CRC) is the third most frequent cancer in women and men, respectively [1]. The main cause of death from CRC is metastasis.[2] MicroRNAs (miRNAs) have been previously shown to be associated with disease progression and metastasis.[3,4,5] These short noncoding RNAs bind complementarily to the 3’-UTR of mRNA targets and thereby repress protein synthesis at the post-transcriptional level.[6] Several miRNAs are expressed differently in primary lesions of CRC as compared to uninvolved colorectal tissues [3]. An association between altered miRNA expression and patient survival has been reported [7]. MiRNAs can foster CRC progression and metastasis by targeting pathogenetically important genes such as anti-oncogenes
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