Fig 2: miR-5100 modulates melanoma cell EMT by targeting SPINK5–STAT3 pathway. A, B Expression of miR-5100 and SPINK5 was measured by RT-qPCR and IHC in melanoma and nevus specimens. C, D The miR-5100 binding site in the 3′-UTR of SPINK5 and matched mutations; miR-5100 modulates SPINK5 expression. Furthermore, a luciferase reporter assay was conducted in 293T cells to verify the interaction between miR-5100 and the SPINK5 binding site. E, F The metastasis inhibition effects of miR-5100 were measured by wound-healing and transwell assays. G miR-5100 modulates melanoma cell EMT process shown by EMT‑related markers determined by western blot analysis. H, I Immunoblotting and IF analysis of STAT3, and phosphorylation of STAT3 in A2058 and G361 cell lines transfected with either a mimic or an inhibitor of miR-5100. *p < 0.05, **p < 0.01, ***p < 0.001 versus control

Fig 3: Metformin inhibits EMT by regulating the miR-5100/SPINK5/STAT3 axis. A IC50 were detected in A2058 and G361 cells (16.61 and 15.1 mM, respectively). B, C Wound-healing and transwell assays were used to determine the effects of metformin in melanoma cell metastasis. D, E Western blot and RT-qPCR were used to detect miR-5100 and relative protein expression after treatment with metformin under a concentration of IC50. F–H miR-5100 mimic reversed metastasis and EMT inhibition effect of metformin in melanoma cells partly. *p < 0.05, **p < 0.01, ***p < 0.001 versus control