ADAM protease inhibition overcomes resistance of breast cancer stem-like cells to γδ T cell immunotherapy

Abstract

Breast cancer stem cells (BCSC) are highly resistant to current therapies, and are responsible for metastatic burden and relapse. Gamma delta T cells (γδTc) are immunosurveillance cells with tremendous anti-tumoral activity, and a growing number of clinical trials have confirmed the safety of γδTc immunotherapy for various malignancies. Herein, we demonstrate that γδTc can kill BCSC, but to a lesser extent than non-cancer stem cells (NSC). Immune evasion was orchestrated by several mechanisms. The BCSC secretome rendered γδTc hypo-responsive by reducing proliferation, cytotoxicity and IFN-γ production, while increasing expression of co-inhibitory receptors on γδTc. BCSC and target cells surviving γδTc cytotoxicity had higher PD-L1 co-inhibitory ligand expression, and blocking PD-1 on γδTc significantly overcame BCSC resistance to γδTc killing. Fas/FasL signaling was dysfunctional in BCSC due to upregulation of the anti-apoptotic protein MCL-1, which could be partially overcome using dMCL1-2, an MCL-1 degrader. Moreover, the BCSC fraction shed higher levels of the NKG2D ligand MICA compared to NSC. Inhibiting MICA shedding using the ADAM inhibitor GW280264X overcame BCSC resistance to γδTc killing, rendering BCSC as sensitive to γδTc cytotoxicity as NSC. Collectively, our data unravel multiple mechanisms exploited by BCSC to evade γδTc killing, which may also come into play in BCSC resistance to other cytotoxic lymphocytes. Developing strategies to overcome this resistance will increase the efficacy of cancer immunotherapy and lead to improved outcomes for cancer patients.

MHC class I chain-related genes B shedding modulates pancreatic tumor immunity via the activation of NKG2DLow T cells

“…MICB is cleaved by ADAM10 and ADAM17 (14,31), primarily expressed in PANC-1. In this study, we discovered that GW280264X (32), which selectively inhibits ADAM10 and ADAM17 (33,34), reduces sMICB production. This reduction in sMICB is accompanied by enhanced activation of NKG2D Low T cells and increased apoptosis of cancer cells during co-culture.…”

γδT cells: alternative treasure in antitumor immunity

“…SeNP-pretreated γδT cells can significantly upregulate the expression of NKG2D, CD16, IFN-γ, and other cytotoxicity-related molecules while downregulating the expression of programmed cell death protein 1 (PD-1), which will prolong the survival time of γδT cells in vitro [61]. Some drugs can affect the susceptibility of tumor cells to toxicity by affecting the NKG2DL-NKG2D axis, Fas-FasL signaling, or TRAIL-TRAILRs signaling between γδT cells and tumor cells; examples of such drugs include, disintegrins and metalloproteinase inhibitors [62], bortezomib [63,64], doxorubicin [65], decitabine [66], temozolomide [67], 4,5-diazafluorene derivatives (14c) [68], carboplatin [69], valeric acid [70]. Pretreatment of tumor cells with these drugs can increase the expression of NKG2DL, Fas, or TRAILRs on their surface, thereby promoting tumor cell apoptosis.…”