Targeting the VIP-VPAC Pathway in Melanoma Models Inhibits Tumor Growth and Liver Metastasis

Uveal melanoma (UVM) is resistant to immune checkpoint therapy and chemotherapy, resulting in high mortality rates, primarily due to liver metastases. While vasoactive intestinal peptide (VIP) signaling has been identified as an immune checkpoint and therapeutic target in pancreatic cancer, its role in melanoma remains unexplored. This study investigated the impact of a novel VIP receptor antagonist, ANT308, on melanoma cell behavior and tumor growth. Using both murine and human UVM/cutaneous melanoma cell lines, we examined the inhibition of VIP receptor signaling and its effects on cell migration and proliferation in vitro. Mechanistically, ANT308 downregulated melanoma cell adhesion molecule (MCAM) and N-cadherin expression at both the RNA and protein levels, as demonstrated by RNA sequencing and Western blot analyses. Knockdown of the VIP receptor VPAC2 in mouse and human melanoma cells produced similar effects on cell migration, proliferation, and MCAM protein expression, further implicating VIP-VPAC2 signaling in tumor progression. In vivo studies revealed that ANT308 treatment decreased MCAM expression in intraocular primary tumors, reduced the number and size of liver metastases following intraocular or subcutaneous melanoma injection, and showed a trend toward reduced tumor volume at the primary tumor site. In conclusion, our findings indicate that VIP receptor signaling promotes liver metastasis in melanoma, and targeting this pathway with VIP receptor antagonists may represent a novel therapeutic strategy for treating metastatic UVM.