miR-216b Targets FGFR1 and Confers Sensitivity to Radiotherapy in Pancreatic Ductal Adenocarcinoma Patients Without EGFR or KRAS Mutation.

Objectives: The success of gemcitabine plus radiotherapy is dependent on the mutation status of pancreatic ductal adenocarcinoma (PDAC) tumors in the EGFR and KRAS genes; however, radiotherapy resistance may also be modulated epigenetically by microRNA (miRNA) regulation. In this study, we examined the potential effect of miRNAs on the resistance to radiotherapy in cases without EGFR or KRAS mutation.

Methods: The association of EGFR and KRAS mutation status and different expression patterns of 6 selected miRNAs related to the EGFR/KRAS signaling pathway were evaluated in the tumors of 42 patients with PDAC.

Results: Reduced miR-216b and miR-217 expression was associated with aggressive tumor characteristics and shortened disease-free survival. In addition, miR-216b expression was reduced 2.7-fold in the cases that did not benefit from therapy, although they did not demonstrate EGFR or KRAS expression (P = 0.0316). A negative correlation between FGFR1 and miR-216b expression (r = -0.355) was found in the tumors of these cases.

Conclusions: Further studies and validations are required; in the tumors of patients with PDAC without activating mutations and induced expression of EGFR/KRAS genes, down-regulated miR-216b expression may be associated with a poor response to radiotherapy via deregulation of another signaling pathway related to FGFR1 signaling.