Significance of microRNA-21 in colorectal cancer pathogenesis.
| Authors | |
|---|---|
| Year of publication | 2008 |
| Type | Article in Proceedings |
| Conference | FEBS Journal |
| MU Faculty or unit | |
| Citation | |
| Field | Oncology and hematology |
| Keywords | colorectal; microRNAs |
| Description | MicroRNAs (miRNAs) are endogenously expressed short non-coding RNAs, that repress protein translation through binding to target mRNAs. Although the number of verified human miRNA is still expanding, only few have been functionally described. However, emerging evidences suggest the involvement of altered regulation of miRNA in pathogenesis of cancers and these genes are thought to function as both tumours suppressor and oncogenes. Previous studies, mainly based on microarrays technology applied on colorectal cancer cell lines, showed altered expression levels of several miRNAs in colorectal cancer (CRC). In our study, we examined by Real-Time PCR expression levels of microRNA-21 (miR-21) in tumors of 29 colorectal cancer patients. For 6 cases of CRC samples also adjacent non-tumor tissues were analyzed. For data normalization we tried different approaches (18S rRNA, GAPDH, let-7a-1). Finally, variability of let-7a-1 expression was shown to be the lowest. Expression levels of miR-21 were significantly higher in tumors comparing to normal mucosa (p = 0,0001). High expression of miR-21 was also associated with lymph node positivity (p = 0,025) and the development of distant metastases (p = 0,009) in CRC patients. To elucidate function of miR-21 in colon cancer cells (DLD1, SW837, HCT116) we tested effects of synthetic 2'OMe-anti-sense-miR-21 (anti-miR-21) transfection (2'OMe-EGFP as control) on their proliferation, cell cycle regulation, sensitization to chemotherapeutic agents (5-fluorouracil, irinotecan, oxaliplatin) and invasive properties. We observed 15-30% decrease of cells proliferation by MTT test after transfection of anti-miR-21 in comparison with control cells. Moreover, cytostatic effect of treatments was enhanced about 20-30% in transfected colon cancer cells. Interestingly, these actions of anti-miR-21 were not associated with significant changes of cell cycle. We hypothesize, that miR-21 affects directly proliferation and now we are testing common markers of proliferation (Ki-67) and those which are possibly under miR-21 post-transcriptional control. Simultaneously, we evaluate changes in invasive properties of anti-miR-21 transfected cancer cells by matrigel invasion assay. Our results suggest possible role of miR-21 in colorectal cancer pathogenesis. Supported by IGA MZ CR NR/9076-4 and project MZ0MOU2005 |