| Description |
Colorectal cancer (CRC) is one of the most common types of cancers worldwide with the high incidence and mortality. Therefore, several efforts have been made to find new diagnostic, prognostic and predictive biomarkers, but also therapeutic targets. One of the promising approaches is the characterization of the solid tumors using microRNAs (miRNAs). MiRNAs are small, non-coding RNAs that post-transcriptionally regulate gene expression. They regulate many biological processes such as cell cycle, apoptosis, proliferation or invazivity and they can also affect anti-cancer therapy efficiency, therefore, their deregulation leads to the origin and progression of many several diseases including CRC. However, only little is known about miRNAs’ target molecules and signaling pathways in which they are involved. We have analyzed expression profiles of 667 miRNAs in 8 patients diagnosed for CRC and 8 paired adjacent non-tumoral tissues using TaqMan Low Density miRNA arrays. We have found miR 215 to be one of the most deregulated miRNAs, therefore its expression was further validated on independent cohort of 250 paired samples and correlated with clinicopathological features of the patients. Afterwards, we investigated its involvement in CRC pathogenesis. We have overexpressed miR 215 in CRC stable cell lines (DLD-1, HCT 116, HT-29, SW620) and analyzed the effect on the viability (MTT test), proliferation (cell counting), cell cycle and apoptosis (flow cytometry), migration of the cells (scratch assay, transwell migration assay) and the ability to found new colonies (colony forming assay). Subsequently, several targets of miR-215 have been identified using quantitative real time PCR, and effects of this miRNA have been also analyzed in vivo on mouse model. We have observed significantly decreased levels of miR-215 in primary CRC tissues and also in metastatic tissue. Moreover, we have found correlation between low expression of this miRNA, clinical stage, lymph node metastasis and disease free survival of the patients. In vitro analyses proved that higher levels of miR-215 lead to the arrest of cell cycle, increased apoptosis and reduced migration and proliferation of the cells. Using qRT-PCR we have identified several potential targets of miR-215 including XIAP, CD164 or HOXB9. The results of in vivo analyses will be the part of the message. The reduced expression of miR-215 has been observed in several tumor diseases, therefore we presume that this miRNA functions as an important tumor suppressor. The results of our study also indicated that miR-215 could serve as a new diagnostic and prognostic biomarker and also potential therapeutic target for the treatment of CRC patients.
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