Recombinant, soluble LIGHT (HVEM ligand) induces increased IL-8 secretion and growth arrest in A375 melanoma cells

The heterotrimeric lymphotoxin alpha (1)beta (2) (LT alpha (1)beta (2)) complex and LIGHT, a new member of the tumor necrosis factor (TNF) superfamily, have been identified as membrane-anchored ligands for the LT beta receptor (LT betaR), a member of the TNF receptor (TNFR) superfamily. Although some of the biologic activities of this receptor have been described using either soluble LT alpha (1)beta (2) as a ligand or agonistic monoclonal antibodies (mAb), very little is known about the signaling of LIGHT via the LT betaR. To gain more insight into the biologic functions of LIGHT, we generated a recombinant soluble form of human LIGHT (rsHuLIGHT). We demonstrate here that this rsHuLIGHT is capable of binding to the LT betaR, Interestingly, receptor-mediated ligand precipitation analysis revealed that rsHuLIGHT bound only to human LT betaR but not to mouse LT betaR, indicating a species-specific receptor ligand interaction. Activation of A375 human melanoma cells by rsHuLIGHT induced an increased secretion of interleukin-8 (IL-8). Furthermore, rsHuLIGHT caused growth arrest of A375 cells even in the absence of interferon-gamma (IFN-gamma).