Thrombospondin 2 drives liver metastasis in skin cutaneous melanoma via regulation of angiogenesis and extracellular matrix remodeling

To explore the functional role of thrombospondin 2 (THBS2) in the metastasis of skin cutaneous melanoma (SKCM), with a focus on its regulation of angiogenesis and extracellular matrix (ECM) remodeling. THBS2 expression was assessed in normal melanocytes and SKCM cell lines with varying metastatic potential. Functional analyses were conducted after THBS2 knockdown in A375 cells and overexpression in G-361 cells. Effects on migration, invasion, endothelial tube formation, and angiogenesis- and ECM-related factors were evaluated. Tumor IMmune Estimation Resource database was used for correlation analyses in SKCM samples. A liver metastasis model was established by intrasplenic injection of B16-F10 cells into Thbs2 knockout and wild-type mice, followed by quantification of hepatic metastases and molecular analysis of peritumoral liver tissue. THBS2 was highly expressed in invasive melanoma cell lines and was positively associated with VEGFA, PECAM1, and MMPs in both databases and experimental models. Knockdown of THBS2 significantly suppressed VEGFA, PECAM1, FGF2, FLT1, MMP2, MMP9, and ECM components (LAMA4, COL1A1, and COL4A1) at mRNA and protein levels, inhibited melanoma cell migration and invasion, and reduced tube formation in human umbilical vein endothelial cells. Overexpression had opposite effects. In vivo , Thbs2 knockout mice exhibited significantly fewer hepatic metastases and reduced metastatic area compared with wild-type controls. Expression of Lama4, Pecam1, Vegfa, Mmp2, and Mmp9 was markedly lower in peritumoral liver tissue of knockout mice. THBS2 promotes SKCM metastasis by enhancing angiogenesis and ECM remodeling. Targeting THBS2 may represent a promising strategy for inhibiting melanoma progression and distant organ colonization.