figure posted on 2023-04-03, 23:06 authored by Ann Mary Joseph, Ratika Srivastava, Jovanny Zabaleta, Eduardo Davila
Co-administration of agonistic 4-1BB antibody and TLR1-TLR2 ligand reduces growth of B16 melanomas in mice.
University of Maryland, Marlene and Stewart Greenebaum Cancer
National Institute of General Medical Sciences
National Institute on Minority Health and Health Disparities
ARTICLE ABSTRACTThe activation of TLR-MyD88 (Toll-like receptor-myeloid differentiation factor 88) signaling within T cells functions as a potent costimulatory signal that boosts antitumor and antiviral responses. However, the molecular mechanisms underlying the costimulatory processes are poorly understood. We compared microarray gene analysis data between TLR1–TLR2-stimulated and unstimulated T-cell receptor transgenic “pmel” and MyD88−/− pmel CD8+ T cells and identified changes in the expression of several TNF family members. In particular, TLR stimulation increased 4-1BB levels in pmel but not in MyD88−/−pmel T cells. A link between 4-1BB and TLR1–TLR2 signaling in CD8+ T cells was highlighted by the suboptimal responses of 4-1BB−/− T cells to TLR1–TLR2 agonist, but their normal response to CD28 or OX40 costimulation. Blocking 4-1BB signaling with antibodies also hindered the costimulatory effects of the TLR1–TLR2 agonist. The elevated levels of 4-1BB transcripts in TLR1–TLR2-stimulated cells were not due to increased mRNA stability nor increased histone activation, but instead were associated with increased binding of p65 and c-Jun to two distinct 4-1BB promoter sites. Combining TLR1–TLR2 ligand with an agonistic antibody to 4-1BB enhanced the antitumor activity in mice with established melanoma tumors. These studies reveal that the costimulatory effects of TLR1–TLR2 signaling in CD8+ T cells are in part mediated by 4-1BB and are important for mounting an effective antitumor immune response. Cancer Immunol Res; 4(8); 708–16. ©2016 AACR.