Comparison of γδ T cell responses and farnesyl diphosphate synthase inhibition in tumor cells pretreated with zoledronic acid

Abstract

Summary Exposing human tumor cells to nitrogen-containing bisphosphonates (N-BPs), such as zoledronic acid (Zol), greatly increases their susceptibility to killing by γδ T cells. Based on this finding and other studies, cancer immunotherapy using γδ T cells and N-BPs has been studied in pilot clinical trials and has shown benefits. Although Zol treatment can render a wide variety of human tumor cells susceptible to γδ T cell killing, there has not been a systematic investigation to determine which types of tumor cells are the most susceptible to γδ T cell-mediated cytotoxicity. In this study, we determined the Zol concentrations required to stimulate half maximal tumor necrosis factor-α production by γδ T cells cultured with various tumor cell lines pretreated with Zol and compared these concentrations with those required for half maximal inhibition of farnesyl diphosphate synthase (FPPS) in the same tumor cell lines. The inhibition of tumor cell growth by Zol was also assessed. We found that FPPS inhibition strongly correlated with γδ T cell activation, confirming that the mechanism underlying γδ T cell activation by Zol is isopentenyl diphosphate (IPP) accumulation due to FPPS blockade. In addition, we showed that γδ TCR-mediated signaling correlated with γδ T cell tumor necrosis factor-α production and cytotoxicity. Some lymphoma, myeloid leukemia, and mammary carcinoma cell lines were relatively resistant to Zol treatment suggesting that assessing tumor sensitivity to Zol may help select those patients most likely to benefit from immunotherapy with γδ T cells.

BTN3A molecules considerably improve Vγ9Vδ2T cells-based immunotherapy in acute myeloid leukemia

“…16 This could account for a poor pAg accumulation in these blasts upon N-BP treatment that would fail to activate Vg9Vd2 T cells. 29 We show that anti-BTN3A 20.1 mAb can sensitize N-BP-poorly sensitized primary AML blasts to Vg9Vd2T cells lysis, notably monocytic Low AML. The sensitization of these resistant blasts to Vg9Vd2 T cells lysis with anti-BTN3A 20.1 mAb points out a potential major role of this mAb to circumvent intrinsic resistance mechanisms in blasts.…”

Zoledronate can induce colorectal cancer microenvironment expressing BTN3A1 to stimulate effector γδ T cells with antitumor activity

“…Given the heterogeneity of the stimulating ability displayed by the various CRC cell lines, we asked whether this was due to a different sensitivity of farnesyl diphosphate synthase to Zol, as reported. 34 However, non-stimulating CRC cell lines were unable to trigger efficiently gd T cell expansion, even when pre-treated with high doses of Zol; furthermore, IPP production in response to Zol, was lower in the three non-stimulating cell lines tested and they did not enhance IPP production in response to high doses of Zol, with the exception of DLD1. Thus, we further investigated any possible difference in the expression of proteins of the butyrophilin family, mainly BTN3A1 that is an essential molecule for the recognition of PAg by gd T lymphocytes, due to its B30.2-binding domain.…”

“…As it has been reported that several tumor cell lines require higher doses of Zol to exert their stimulating activity of gd T cells, 34 three low-stimulating (SW620, HCT15, DLD1) and one stimulating (LS180) CRC cell lines were pre-treated (4 h) with high doses (100 mM and 50 mM) of Zol, washed and co-cultured with purified T cells as above. As shown in Fig.…”

“…[39][40][41] In some experiments, the CRC cell lines LS180, DLD1, HCT15 and SW620 were pre-treated for 4 h with 100 mM or 50 mM Zol, then washed and used for stimulation experiments. 34 In other experiments, 5 mM Zol was added to the cell suspensions obtained from CRC patients' specimens. On the third day, IL-2 (4 ng/mL) was added and every 2 d complete medium supplemented with IL-2 was changed.…”

Human Vγ9/Vδ2 T cells: Innate adaptors of the immune system

“…In all other bacteria as well as in higher eukaryotes including humans, IPP and DMAPP are generated via the mevalonate pathway that is closely regulated by the action of 3-hydroxy-3-methyl-glutaryl-CoA reductase and downstream enzymes such as farnesyl pyrophosphate synthase. Overproduction of the low bioactivity compounds IPP and DMAPP as a result of a dysregulation of the mevalonate pathway in human cells, be it in metabolically active tissues including tumor cells or through inhibition of farnesyl pyrophosphate synthase by aminobisphophonates such as zoledronate, is thought to render such cells targets of Vc9/Vd2 T cells, despite the absence of the high bioactivity metabolite HMB-PP in this context [11,[16][17][18]. Zoledronate and related drugs are therefore receiving substantial attention as Vc9/Vd2 T cellstimulating agents in vivo especially with respect to immunotherapies against advanced solid and hematological tumors [19][20][21].…”