Screening and preliminary validation of miRNAs with the regulation of hTERT in colorectal cancer

The overexpression of human telomerase reverse transcriptase (hTERT) has been associated with the invasion and metastasis of colorectal cancer (CRC) and has received extensive attention, although the underlying mechanism involved remains unclear. The aim of the present study was to screen and preliminarily validate new tumor-suppressor microRNAs (miRNAs) that potentially inhibit hTERT expression and to assess its clinical significance. Screening for downregulated miRNAs in CRC tissues was performed by retrieving and analysing microRNA microarray data. miRNA candidates were then filtered by bioinformatics analysis. The expression of miRNAs candidates was verified by quantitative polymerase chain reaction in the CRC and corresponding normal tissues. Immunohistochemistry (IHC) was used for the detection of hTERT protein expression. Spearman’s correlation coefficient between miRNA candidates and hTERT protein expression was calculated (r) to identify hTERT-targeting miRNAs. A survival analysis was performed to assess the prognostic significance of hTERT-targeting miRNAs in CRC. Eight miRNAs with the potential to interact with hTERT were predicted: miR-29c-3p, miR-124-3p, miR-133a-3p, miR-133b, miR-138-5p, miR-150-5p, miR-378a-3p and miR-422a, respectively. Following detection of the miRNAs using RT-qPCR, miR-29c-3p was excluded. miR-138-5p and miR-422a were observed to potentially interact with hTERT (r=−0.362, P=0.001; r=−0.306, P=0.005, respectively). The Kaplan-Meier survival curves demonstrating high- vs. low-expression group of miR-422a showed a highly significant difference in CRC patients (P=0.024), which suggests that the downregulation of miR-422a was associated with a poorer prognosis. The results indicated that miR-138-5p and miR-422a potentially inhibited hTERT expression in CRC, and suggest a potential application of miR-422a in prognosis prediction and CRC treatment.