MicroRNA profiling in oesophageal adenocarcinoma cell lines and patient serum samples reveals a role for miR-451a in radiation resistance [patients with Oesophageal Adenocarcinoma]

Many patients with Oesophageal Adenocarcinoma (OAC) that undergo chemoradiotherapy do not benefit from treatment due to therapy resistance. We therefore investigated the association of microRNAs, which regulate gene expression, with the response to individual treatments, focusing on radiation, to both better understand the mechanisms involved in resistance and to find potential biomarkers. Intrinsic radiation resistance and chemotherapy drug resistance were assessed in 8 OAC cell lines, and miRNA expression profiling was performed via high throughput qPCR. miRNAs were discovered that were either uniquely associated with resistance to radiation, cisplatin, or 5-FU, or were common to 2 or all 3 of the treatments. Target mRNA pathway analyses indicated several potential mechanisms of treatment resistance. miRNAs associated with the in-vitro treatment responses were then investigated for association with pathologic response to neoadjuvant chemoradiotherapy (nCRT) in pre-treatment serums of 39 patients with OAC. Hsa-miR-451a was associated uniquely with resistance to radiation treatment in the cell lines, and with the response to nCRT in patient serums. Inhibition of hsa-miR-451a in the radiation resistant OAC cell line OE19 increased radiosensitivity (Survival Fraction 73% vs. 87%, p=0.0003), and altered RNA expression. Pathway analysis of effected small non-coding RNAs and corresponding mRNA targets suggest potential mechanisms of radiation resistance in OAC. 39 patients with locally advanced (no distant metastases) Oesophageal Adenocarcinoma who received a nCRT protocol that included radiation (41.4 Gy), carboplatin and paclitaxel.