Shedding of endogenous MHC class I‐related chain molecules A and B from different human tumor entities: Heterogeneous involvement of the “a disintegrin and metalloproteases” 10 and 17

Abstract

The interaction of the MHC class I-related chain molecules A and B (MICA and MICB) with the corresponding natural killer group 2, member D (NKG2D) receptor triggers cytotoxic effector activity of natural killer cells and certain T-cell subsets and provides a costimulatory signal for cytokine production. Thus, the presence of MICA=B on transformed cells contributes to tumor immunosurveillance. Consequently, the proteolytic cleavage of MICA=B is regarded as an important immune escape mechanism of various cancer cells. To investigate the molecular machinery responsible for the shedding of endogenous MICA=B, we analyzed different human tumor entities including mammary, pancreatic and prostate carcinomas. Flow cytometry and enzyme-linked immunosorbent assay (ELISA) revealed that all tested tumor cells constitutively expressed MICA and MICB on the cell surface and also released NKG2D ligands into the supernatant. We demonstrate that the "a disintegrin and metalloproteases" (ADAMs) 10 and 17 are largely responsible for the generation of soluble MICA=B. Pharmacological inhibition of metalloproteases reduced the level of released MICA=B and increased cell surface expression. Studies using RNA interference not only revealed a prominent role of ADAM10 and ADAM17 in NKG2D ligand shedding but also a tumor cell-specific role of ADAM10 and=or ADAM17 in shedding of MICA or MICB. Moreover, we report that in the prostate carcinoma cell line PC-3, MICA was not shed at all but rather was secreted in exosomes. These data indicate that the release of NKG2D ligands from individual tumor entities is by far more complex than suggested in previously reported MICA=B transfection systems.The activating natural killer group 2, member D (NKG2D) receptor is expressed on NK cells, NKT cells, gd T cells, CD8 1 T cells and a minor immunoregulatory subset of CD4 1 T cells. 1,2 The ligation of NKG2D costimulates T cells but also directly triggers cell-mediated cytotoxicity and cytokine release in NK cells. [3][4][5][6] Thus, despite some exceptions including gastrointestinal epithelium 7 and placenta, 8 the ligands for NKG2D are not expressed on healthy tissues to avoid inadvertent damage. However, NKG2D ligand (NKG2DL) expression can be induced in response to a variety of stimuli related to cellular stress such as heat shock, viral infection, DNA damage, oxidative stress and certain proinflammatory signals. 9,10 Of note, many tumors and precancerous lesions express NKG2D ligands presumably as a bystander effect of the oncogenic process itself. 11 As NKG2DL expression renders tumors susceptible to NKG2D 1 lymphocytes, the NKG2D system plays a pivotal role in immunosurveillance. 12 On the other hand, the sustained exposure to tumor cell-bound NKG2D ligands might also result in surface modulation and functional impairment of the NKG2D receptor and induce cross-tolerance of additional NK cell activation pathways. 13,14 A hallmark of the NKG2D system is the multitude of ligands identified so far. In humans, these include the MHC class I-related chain ...

Genotoxic Stress Induces Senescence-Associated ADAM10-Dependent Release of NKG2D MIC Ligands in Multiple Myeloma Cells

“…Several studies, primarily performed in different types of tumor cell lines or transfected cells in steady-state conditions, indicate the direct involvement of both ADAM10 and ADAM17 enzymes in MICA and MICB release, but the relative contribution of these enzymes is still controversial. Boutet et al (32) found that ADAM17 mediates MICB proteolytic cleavage in CV1 epithelial transfectants; however, recent evidence highlights a cell type-specific role for these metalloproteinases (33). Our results also reveal high levels of ADAM10 expression in several MM cell lines and in primary malignant PCs, with enzyme expression not correlating with the disease stage.…”

“…To investigate whether drug-induced MICB release involves metalloproteinase activity (32,33), we evaluated MICB levels in the supernatants of DOX-and MEL-treated SKO-007(J3) cells in the presence of the metalloproteinase inhibitor marimastat. As MICA gene typing was performed as described in Materials and Methods.…”

“…The relative roles for ADAM10 and ADAM17 metalloproteinases on MIC shedding were primarily investigated in steady-state conditions in a variety of tumor cell lines or transfected cells (9,(32)(33)(34). To identify the ADAM enzymes responsible for the druginduced MICB release, we examined whether the inhibition of ADAM10 and ADAM17 expression on drug-treated MM cells interfered with MICB shedding.…”

Increased sMICA and TGFβ 1 levels in HNSCC patients impair NKG2D-dependent functionality of activated NK cells

“…29 Tumor shedding of the NKG2D ligands, which provide a means for tumor cell immune evasion, has been found to be regulated by ADAMs (a disintegrin and metalloproteases), 10 and 17, indicating that proteolytic cleavage of surface molecules is an undesirable characteristic of tumor cells. 30,31 The release of this NKG2D ligand is strongly associated with a systemically reduced NKG2D expression on the surface of circulating blood lymphocytes, especially cytotoxic CD56 C / CD3 ¡ NK cells, CD8 C ab and gd T cells, resulting in attenuated recognition of transformed and malignant cancer cells and decreased tumor surveillance. 10,32,33 The results of our current study confirm the impact of sMICA in the disease staging because untreated HNSCC patients diagnosed with Stage IV disease had markedly elevated sMICA levels in their blood plasma as compared with those of lower disease stages.…”

Neoadjuvant chemotherapy for pancreatic cancer: Effects on cancer tissue and novel perspectives

“…However, cancer cells promote immune escape by ectodomain shedding of MICA and produce soluble MICA that competitively inhibits NKG2D expression on the surface of NK cells. The key molecule that activates the shedding protease, including a disintegrin and metalloproteinases 9, 10 and 17, is considered to be transforming growth factor (TGF)-β (96)(97)(98). Therefore, treatments that inhibit TGF-β are important in antitumor immunity (99).…”