[Overexpression of multimerin-2 promotes cutaneous melanoma cell invasion and migration and is associated with poor prognosis]

To investigate the inhibitory effect of multimerin-2 (MMRN2) overexpression on growth and metastasis of cutaneous melanoma cells.

Clinical data of patients with cutaneous melanoma were obtained from the GEO database to compare MMRN2 expressions between normal and tumor tissues. A protein-protein interaction network was constructed using the STRING database, and the intersecting genes from GEPIA2.0 were subjected to GO and KEGG enrichment analysis. The prognostic relevance of MMRN2 expression level was assessed using Cox regression and "timeROC". The correlations of MMRN2 expression level with immune infiltration and angiogenesis-related genes were analyzed using GSCA database and the ssGSEA algorithm. Colony-forming assay, Transwell assay, and wound healing assay were used to examine the changes in proliferation and migration of cultured cutaneous melanoma cells following MMRN2 knockdown. In a mouse model bearing cutaneous melanoma xenograft, the effect of MMRN2 knockdown on vital organ pathologies, survival of the mice and GM-CSF, CXCL9, and TGF‑β1 protein expressions were analyzed.

MMRN2 was significantly upregulated in metastatic cutaneous melanoma (P<0.001). Protein interaction network analysis identified 15 intersecting genes, which were enriched in endothelium development and cell-cell junctions. In patients with cutaneous melanoma, a high MMRN2 expression was correlated with a poor prognosis, an advanced T stage, a greater Breslow depth, and ulceration (P<0.05). MMRN2 expression level was strongly correlated with 24 immune cell types (P<0.001), fibroblasts, endothelial cells, and expressions of the pro-angiogenic genes (KCNJ8, SLCO2A1, NRP1, and COL3A1; P<0.001). In cultured B16F10 cells, MMRN2 knockdown significantly suppressed cell proliferation, migration and invasion and caused remo-deling of the immunosuppressive microenvironment.

MMRN2 overexpression drives progression of cutaneous melanoma by enhancing tumor metastasis, angiogenesis and immune evasion, highlighting its potential as a therapeutic target for melanomas.