Background MicroRNAs (miRNA) have potential as prognostic biomarkers and therapeutic targets in cancer. A study was undertaken to investigate the association between miRNA expression patterns and the prognosis and therapeutic outcome of colorectal cancer (CRC).

Methods miRNA expression profiling in tumour, adenoma and normal colorectal tissues was performed to identify tumour-related miRNAs in the course of colorectal malignant changes. Quantitative reverse transcription PCR (qRT-PCR) assays were used to measure tumour-related miRNA and to assess its association with survival and response to adjuvant chemotherapy in 239 patients. In addition, to validate the findings, associations of the tumour-related miRNA with clinical characteristics of CRC were analysed in 185 patients by in situ hybridisation (ISH) analysis.

Results Only one miR-150 was found to show a decrease in expression levels in the three tissue groups (normal, adenoma and cancer tissue) in parallel with increasing carcinogenesis of the colorectal tissue. In both ISH and qRT-PCR analysis, tumour tissue had reduced levels of miR-150 expression compared with paired non-cancerous tissue, which indicated that the levels of miR-150 expression were associated with CRC. Moreover, patients whose tumours had low miR-150 expression had shorter survival and a worse response to adjuvant chemotherapy than patients whose tumours had high miRNA expression.

Conclusions The miR-150 expression status of patients with CRC is associated with survival and response to adjuvant chemotherapy. It is suggested that miR-150 should be considered as a potential biomarker associated with the prognosis and therapeutic outcome in CRC.