Fig. 3

Possible regulatory mechanism of miRNAs in PNI of tumor. Pro-PNI miRNAs: miR-15a-2, miR-195, miR-224, miR-10 (a/b), miR-125b (− 1/2), miR-30a/b/c-2, miR-26a (− 1/2), miR-126, miR-145, miR-151, miR-99b, miR-100, miR-181a-1, miR-191, miR-21, miR-23a, miR-27, miR-17, miR-191, miR-3679-5p, miR-9-3p and miR-205, miR-589-3p, miR-128-3p, miR-24 and miR-27a. Anti-PNI miRNAs: miR-31, miR-370, miR-216, miR-124-3p, miR-133a, miR-204, miR-137 and miR-7. Dual role of miRNAs family in PNI: miR-200 family, miR-141 (pro-PNI), miR-429 (anti-PNI); Let-7 family, let-7a (anti-PNI), let-7d and Let-7g (pro-PNI)