MicroRNA-7 is associated with malignant potential and poor prognosis in human colorectal cancer

Dysregulation pattern of microRNA-7 (miR-7) and the clinical significance of its expression in colorectal cancer (CRC) are unresolved. Here, we investigated the relationship between clinicopathological factors, including prognostic outcome, and miR-7 expression in CRC tissues. We analyzed miR-7 expression levels by real-time reverse transcription polymerase chain reaction in 210 colorectal tissues (196 CRCs and 14 normal mucosae from healthy volunteers). miR-7 expression levels were significantly upregulated in CRC tissues compared to normal colorectal mucosae. Elevated miR-7 expression was significantly correlated with tumour depth, venous invasion, lymphatic invasion, lymph node metastasis, and liver metastasis. High miR-7 expression was significantly associated with poor overall survival in patients with CRC (p=0.010). Moreover, miR-7 expression was an independent prognostic factor in patients with CRC (hazard ratio=1.854, 95% confidence interval=1.016-3.540; p=0.044). miR-7 acts as an oncogene in CRC and is significantly associated with tumour progression and poor prognosis.