UVA Irradiation Promotes Melanoma Cell Proliferation Mediated by OPN3 Independently of ROS Production.

UVA radiation, a primary risk factor in melanoma progression, partly acts through the mediation of reactive oxygen species (ROS). The role of ROS in driving cutaneous melanoma toward an invasive phenotype and whether it occurs through opsins (OPNs), which are photosensitive G protein-coupled receptors, is not fully understood. This study focuses on the impact of UVA radiation on melanoma cell proliferation, with a special emphasis on OPN3. Investigating the biphasic response to various UVA doses (0.75-9 J/cm²) in A375 and MV3 cell lines, and using EdU and CCK-8 assays, we observed dose-dependent changes in cell proliferation. Interestingly, UVA irradiation at these doses of 0.75, 1.5 and 3 J/cm² did not significantly induce ROS production. Our study further delves into the role of OPN3, a photosensitive receptor, in melanoma progression. Following UVA exposure, an increase in OPN3 expression was observed in melanoma cells lines A375 and MV3, indicating its role as a UVA-sensitive sensor and its influence on cell proliferation. Additionally, UVA-induced calcium flux in two melanoma cells lines pointed to a calcium-dependent G protein-coupled pathway in melanoma proliferation, mediated by OPN3 and not reliant on ROS. This research sheds light on the mechanism of UVA-induced melanoma progression, underscoring OPN3 as a pivotal regulator and advancing our understanding of UVA's interaction with opsins in melanoma progression.