BACKGROUND: 5-Fluorouracil (5-FU) based treatment is the standard therapy for metastatic colorectal cancer (CRC), but the development of chemoresistance is inevitable. Increasing evidence shows that dysregulation of microRNAs (miRNAs) is involved in malignant transformation. Thus, it is imperative that we find new diagnostic and prognostic marker for chemotherapy in CRC.

MATERIAL AND METHODS: For clinical parameter analysis, 78 CRC tissues and adjacent normal tissues and 45 serum specimens from CRC patients were included in this study. For chemo-response analysis, 116 primary tissues were collected from the patients receiving first-line 5-FU treatment. Quantitative Real-Time PCR (qRT-PCR) was used to detect microRNAs expression.

RESULTS: The expression of miR-429 was significantly increased in both serum and primary tissues from CRC patients, and enhanced miR-429 level was associated with tumor size, lymph node metastasis, and TNM stage. The diagnostic and prognostic values were also confirmed in CRC by using primary tissues. For patients receiving 5-FU-based treatment, miR-429 levels were significantly lower in responding group. The proportions of patients that did not experience response to therapy were higher in primary tumors with high miR-429 expression levels as compared with primary tumors with low miR-429 expression levels. Finally, Kaplan-Meier survival analysis showed that miR-429 is an independent prognostic indicator for chemo-response to 5-FU therapy among CRC patients.

CONCLUSIONS: High level of miR-429 expression was correlated with enhanced malignant potential and poor prognosis of CRC patients. Furthermore, miR-429 could affect the chemo-sensitivity of CRC patients to 5-FU therapy and was associated with poor response to 5-FU-based chemotherapy in patients with CRC.

Keywords: Colorectal Neoplasms, Fluorouracil