Distant metastasis is a major cause of deaths in patients with colorectal cancer, which is partly due to lack of robust metastasis-predictive biomarkers.
In spite of the important function of microRNA (miR)-203 in cancer metastasis, its clinical significance in colorectal cancer metastasis remains unknown.
Here, Dr Ajay Goel and colleagues from Texas, USA evaluated the potential role of serum miR-203 as a non-invasive biomarker for colorectal cancer metastasis.
MiR-203 expression was quantified by quantitative reverse-transcription PCR in 58 pairs of primary colorectal cancer and corresponding matched liver metastasis, as well as 186 serum and 154 matched tissue specimens from patients with colorectal cancer in cohort 1.
Next, the team performed validation of miR-203 levels in serum from 144 patients with colorectal cancer in an independent cohort.
|MiR-203 expression was significantly upregulated in liver metastasis|
Mouse models of colorectal cancer-associated metastases were established to identify the source of circulating miR-203.
The researchers determined expression patterns of miR-203 in tissues by in situ hybridization.
MiR-203 expression was significantly upregulated in liver metastasis compared with matched primary colorectal cancer tissues.
The researchers found that serum miR-203 levels were significantly upregulated in a stage-dependent manner, and high miR-203 expression was associated with poor survival in patients with colorectal cancer in both patient cohorts.
The team noted that increased miR-203 levels in serum indicated high risk for poor prognosis, as well as metastasis to lymph nodes, liver, peritoneum and distant organs.
The research team found that serum miR-203 levels were significantly higher in animals with liver or systemic metastasis compared with controls.
Dr Goel's team concludes, "High levels of serum miR-203 associate with poor survival and metastasis, suggesting it to be a promising non-invasive prognostic and metastasis-predictive biomarker in patients with colorectal cancer."