Polyinosinic-cytidylic acid as an adjuvant on natural killer- and dendritic cell-mediated antitumor activities

Previously, we demonstrated that treatment with E7(44–62) and the adjuvant polyinosinic-cytidylic acid (poly(I:C)) in a rodent model generates antitumor immune responses, but the effect of E7(44–62) with poly(I:C) on natural killer (NK)- and dendritic cell (DC)-mediated antitumor activities is still unclear. Our goal was to examine the antitumor effects of E7(44–62) with poly(I:C). We examined the ability of E7(44–62) with poly(I:C) to induce toll-like receptor 3 (TLR3) expression, tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) mRNA expression, and tumor cell-killing activity in human NK cells as well as its ability to induce CD11c and CD86 expression and proliferation in human DCs. We found that E7(44–62) with poly(I:C) treatment markedly increased TLR3 expression and cytotoxicity against HeLa cells in human NK92 cells. Moreover, treatment with E7(44–62) and poly(I:C) markedly up-regulated IFN-γ and TNF-α mRNA expression in NK92 cells. Human patients with cervical cancer exhibited a marked decrease in the frequency of DCs; however, ex vivo treatment with E7(44–62) and poly(I:C) restored DC frequency. Stimulation of human DCs in patients with E7(44–62) and poly(I:C) led to high levels of CD11c and CD86 expression. Our data reveal the involvement of E7(44–62) combined with poly(I:C) in potentiating antitumor cytotoxicity and cytokine-producing activities in human NK92 cells and DCs.