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

The heterotrimeric lymphotoxin alpha(1)beta(2) (LTalpha(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 LTbeta receptor (LTbetaR), a member of the TNF receptor (TNFR) superfamily. Although some of the biologic activities of this receptor have been described using either soluble LTalpha(1)beta(2) as a ligand or agonistic monoclonal antibodies (mAb), very little is known about the signaling of LIGHT via the LTbetaR. 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 LTbetaR. Interestingly, receptor-mediated ligand precipitation analysis revealed that rsHuLIGHT bound only to human LTbetaR but not to mouse LTbetaR, 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).