Evaluation of miR-21 and miR-375 as prognostic biomarkers in oesophageal cancer in high-risk areas in China

MicroRNAs have been associated with prognosis in oesophageal cancer (EC), suggesting that miRNAs could play a role in guiding treatment decisions. The aim of this study was to evaluate the prognostic potential of miRNAs found to be associated with zinc deficiency in a geographical area with a high incidence of EC. miRNAs found to be associated with zinc deficiency were isolated from EC cell lines cultured with various Zn levels. The expression levels of the miRNAs were quantified using qRT-PCR. The potential prognostic value of the selected miRNAs was assessed in a cohort study of 88 patients from an area in China with a high incidence of EC. Correlations between miRNAs and patient characteristics were assessed using χ² statistical tests or Fisher’s exact test. A Cox proportional hazards model was used to assess the correlations between miRNAs and overall survival (OS). Forest plots were performed to evaluate the prognostic impact of the miRNAs examined in the present study in the Asian population. The expression levels of miR-21, miR-31, miR-93 and miR-375 were different when Zn levels were varied in EC cell lines, but only miR-21 and miR-375 were associated with patient characteristics and prognosis in patients with EC from an area of China with a high incidence of EC. The patients expressing high levels of miR-21 had poor OS (HR 2.15, 95% CI 1.16–3.97), whereas those with high levels of miR-375 had improved OS (HR 0.47, 95% CI 0.26–0.87).The patients with both a high level of miR-375 and a low level of miR-21 had significantly better outcomes. Forest plots based on an analysis of this Asian population indicated that a high level of miR-21 significantly predicted a shortened OS (HR 1.83, 95% CI 1.42–2.37), whereas a high level of miR-375 was significantly correlated with increased survival (HR 0.56, 95% CI 0.43–0.73). MiR-21 and miR-375 could be used as prognostic biomarkers in areas with a high incidence of EC, and combining these markers may results in a better effect.