High levels of miR-221 expression were associated with Lgr5<sup>+</sup> cells in mouse colon crypts and reduced survival in patients with colorectal carcinoma.
The RT‑qPCR analysis of 101 CRC samples showed that a high expression level of miR‑221 or miR‑222 in the cancer stroma was associated with liver metastasis, distant metastasis, and shorter overall survival rate of patients with CRC (P<0.05).
In the present study, we demonstrate the predictive value of long non-coding RNA GAS5 (lncRNA GAS5) and mircoRNA-221 (miR-221) in the prognosis of colorectal cancer (CRC) and their effects on CRC cell proliferation, migration and invasion.
Expression levels of miR-21 (p<0.0001) and miR-221 (p<0.0001) were significantly higher, whereas expression levels of miR-150 (p=0.0054) were significantly lower in the blood samples of patients with colorectal cancer in comparison to the control group.
Increased activities of miR-221* and miR-224 reduce growth and metastasis of CRC xenograft tumors in mice; these miRs might be developed as therapeutic reagents or biomarkers of CRC progression.
Apart from their role in regular metabolism, abnormal profiles of miRNA expression accompany cancer transformation, including colorectal cancer (CRC) metastasis. microRNAs may play a role in each phase of CRC metastasis including angiogenesis, invasion, intravasation, circulation, extravasation and metastatic colonization. microRNA levels may serve as a predictive CRC marker, which was confirmed by the serum level of miR-29a targeting KLF4, a marker of cell stemness, and the plasma level of miR-221 down-regulating c-Kit, Stat5A and ETS1, which are signal transducers and transcription factor, respectively.
We previously found that oncogenic KRAS induces increased expression of microRNAs (miRNAs), such as miR-200c and miR-221/222, in human colorectal cancer (CRC) HCT116 cells in a three-dimensional (3D)-specific manner, however, the regulation of miRNA expression through oncogenic KRAS in other types of CRC remains unclear.
MiR-221 binds to the target site in the 3'-UTR of the CDKN1C/p57 mRNA to inhibit CDKN1C/p57 expression by post-transcriptional gene silencing to promote CRC occurrence and progress, therefore serving as a potential therapeutic target for the prevention and treatment of CRC.
Kaplan-Meier curve assessment shows that the elevated plasma miR-221 level is a significant prognostic factor for poor overall survival in CRC patients.