The abundance of desmoplastic stroma and high levels of miR-21 expression were strong indicators of LNI, and may thus help the surgeon to choose the extent of cervical lymph node dissection for large, sporadic MTCs with no preoperatively obvious LNI.
Further studies should investigate the role of miR-21 as a prognostic biomarker and the feasibility of using PDCD4-restoring strategies as a therapeutic approach to MTC.
MTC and CCH were both characterized by a significant overexpression of the whole set of miRNAs (the increase being 4.2-fold for miR-21, 6.7-fold for miR-127, 8.8-fold for miR-154, 6.6-fold for miR-224, 5.8-fold for miR-323, 6.1-fold for miR-370, 13-fold for miR-9*, 6.7-fold for miR-183, and 10.1 for miR-375, p<0.0001).