沉默HIG2促进NK细胞对喉癌细胞杀伤敏感性的机制探讨

目的:探讨缺氧诱导基因2（HIG2）在喉癌细胞逃逸NK细胞免疫杀伤中的作用机制。方法:免疫组织化学法检测喉癌组织和癌旁组织中HIG2的表达;Western blot检测HIG2、NKG2D配体（MICA、MICB、ULBP1、ULBP2和ULBP3）的蛋白表达;Transwell实验检测Hep-2细胞的侵袭;流式细胞术检测Hep-2细胞的凋亡、CD3-CD56+的NK细胞纯度、NKG2D受体表达及Hep-2细胞NKG2D配体的表达;乳酸脱氢酶释放法检测不同效靶比时,NK细胞对Hep-2细胞的杀伤活性。结果:HIG2在喉癌组织中高表达。CD3-CD56+的NK细胞纯度大于90%。沉默HIG2抑制Hep-2细胞侵袭,促进细胞凋亡,提高NKG2D配体的表达,增强NK细胞对Hep-2细胞的杀伤敏感性。NKG2D抗体抑制NK细胞NKG2D受体表达,减弱NK细胞对沉默HIG2 的Hep-2细胞的杀伤活性。结论:沉默HIG2可抑制喉癌细胞侵袭,促进细胞凋亡,上调NKG2D配体表达,增强NK细胞对喉癌细胞的杀伤敏感性。     

苦参碱诱导自然杀伤细胞对白血病K562细胞杀伤的实验研究

目的 探讨中药苦参碱对人自然杀伤（NK）细胞体外杀伤白血病细胞的作用及可能的分子机制.方法 以人慢性粒细胞白血病K562细胞为靶细胞,采用CFSE/PI双染色法流式细胞术检测不同质量浓度（02、0.5、0.8 mg/ml）苦参碱处理后,人NK细胞在不同效靶比下对K562细胞的体外杀伤活性.流式细胞术分析不同浓度苦参碱处理24 h对NK细胞主要活化性受体NKG2D和抑制性受体CD158a、CD158b表达的影响及K562细胞膜上NKG2D配体MICA/B、ULBP1、ULBP 2、ULBP 3表达的改变.结果 效靶比为5∶1时,NK细胞对0.2、0.5和0.8 mg/ml苦参碱处理后的K562细胞杀伤率分别为32.8％、38.1％和40.5％,较处理前均有不同程度增高（29.2％）;但进一步增加效靶比（10：1）后,NK细胞杀伤活性改变差异无统计学意义（P＞0.05）.苦参碱处理24 h,NK细胞抑制性受体CD158a、CD158b的表达均较处理前降低,而活化受体NKG2D的表达则增高.K562细胞表面NKG2D配体ULBP1和ULBP2分子的表达也较处理前增高（平均荧光强度分别为174.33±39.93比275.67±32.88,517.6±47.97比1368.6±49.43,P＜0.05）.结论 苦参碱可增强NK细胞对白血病K562细胞的体外杀伤活性,其机制可能与NK细胞受体及配体表达调节作用有关.     

Regulation of the expression of MHC class I-related chain A, B (MICA, MICB) via chromatin remodeling and its impact on the susceptibility of leukemic cells to the cytotoxicity of NKG2D-expressing cells.

Innate immune cells such as natural killer (NK) cells play a crucial role in antitumor immune responses. NKG2D is a major activating immunoreceptor expressed in not only NK cells but also CD8+ T cells and shows cytotoxicity against tumors by recognizing its ligands major histocompatibility complex class I-related chain A and B (MICA and MICB) on tumor cells. Recently, it has been suggested that NKG2D-mediated cytotoxicity correlates with the expression levels of NKG2D ligands on target cells. In this study, we were able to increase the expression levels of MICA and MICB on leukemic cell lines and patients' leukemic cells by treatment with trichostatin A (TsA), a histone deacetylase (HDAC) inhibitor. Chromatin immunoprecipitation (ChIP) assays revealed that treatment with TsA resulted in increased acetylation of histone H3 and decreased association with HDAC1 at the promoters of MICA and MICB. Intriguingly, upregulation of MICA and MICB by treatment with TsA led to enhancement of the susceptibility of leukemic cells to the cytotoxicity of NKG2D-expressing cells. Our results suggest that regulation of the expression of NKG2D ligands by treatment with chromatin-remodeling drugs may be an attractive strategy for immunotherapy.     

NKG2D配体在13种肿瘤细胞系中的表达及意义

背景与目的:NKG2D及其配体的相互作用在肿瘤免疫监视中起着非常重要的作用。本研究探讨NKG2D配体在13种肿瘤细胞系中的表达及其意义。方法:采用半定量RT-PCR法检测肿瘤细胞系中NKG2D配体的mRNA表达。应用MTT法检测人NK细胞对肿瘤细胞的杀伤活性,免疫组织化学技术和Western blot法检测肿瘤细胞中MHCⅠ类相关蛋白A(MHC classⅠchain-related A)蛋白表达情况。结果:13种肿瘤细胞系表达不同水平的NKG2D配体mRNA。其中Hep2细胞中MICA强阳性表达,HeLa、HepG2、MDA231、HT29、SGC7901、M21、K562、Jurkat细胞MICA表达阳性,而Caski、PG、HL-60和Raji细胞中MICA mRNA阴性。MICA和MICB的表达水平与NK细胞杀伤活性具有高度相关性(r=0.851,P<0.001;r=0.652,P<0.05)。除ULBP3外,其余ULBP成员的表达水平与NK细胞杀伤均无相关性。结论:在6种人NKG2D配体中,MICA的表达水平与肿瘤细胞对NK细胞杀伤的敏感性关系最为密切,肿瘤细胞MICA的表达水平可能决定着机体NK细胞抗肿瘤免疫应答的强弱。     

乳腺癌患者可溶性MICA对自然杀伤细胞受体的影响

目的观察乳腺癌患者外周血自然杀伤（NK）细胞杀伤活性及受体的变化,探讨可溶性MICA（sMICA）对NK细胞受体及杀伤活性的影响。方法ELISA法检测外周血血清sMICA的含量。流式细胞术（FCM）检测NK细胞百分比、NK细胞活化性受体NKG2D、抑制性受体KIR（CD158b）表达。MTT法检测NK细胞对乳腺癌细胞株MCF-7的杀伤活性。结果与健康人比较,乳腺癌患者中81．6％表达sMICA,含量为（205．36±71．27）ng／L,且sMICA含量与TNM分期呈正相关。乳腺癌患者外周血NK细胞所占百分比无明显差异,但血清sMICA阳性的乳腺癌患者中NK细胞杀伤活性明显降低,NKG2D表达下降,CD158b表达增高。当NK细胞培养体系中加入sMICA阳性的乳腺癌血清时,其杀瘤活性明显降低【（76．2±6．7）％与（48．4±4．1）％】,NKG2D的表达明显下调[（92．5±7．1）％与（62．5±6．4）％],而CD158b的表达明显上升【（10．6±3．2）％与（43．6±3．4）％】。sMICA阳性的乳腺癌患者NK细胞与细胞因子IL-15共培养,NK细胞的杀瘤活性、NKG2D的表达明显升高,KIR（CD158b）的表达明显下降。结论乳腺癌外周血血清中sMICA可通过下调NK细胞NKG2D表达以及上调KIR表达,降低NK细胞杀瘤活性。IL-15可逆转sMICA对NK细胞的免疫下调作用。     

Differential modulation of natural killer cell cytotoxicity by 17β-estradiol and prolactin through the NKG2D/NKG2DL axis in cervical cancer cells

Natural killer (NK) cells play a crucial role in cervical cancer (CC). As estrogens and prolactin (PRL) have been reported to be involved in CC, the present study attempted to elucidate the effects of both hormones on NK cells in CC. For this purpose, NKL cells, as well as CC-derived cell lines (HeLa, SiHa and C33A) and non-tumorigenic keratinocytes (HaCaT cells) were stimulated with 17β-estradiol (E2; 10 nM), PRL (200 ng/ml), or both (E2 and PRL) for 48 h. The expression of hormone receptors (estrogen receptor α and β, G protein-coupled estrogen receptor 1 and PRL receptor) and NK cell activating receptors [natural killer group 2D (NKG2D), natural cytotoxicity triggering receptor 3, natural cytotoxicity triggering receptor 2 and natural cytotoxicity triggering receptor 1] were measured using western blot analysis and flow cytometry, respectively. In the HeLa, SiHa, C33A and HaCaT cells stimulated with the hormones, the expression of NKG2D ligands [MHC class I polypeptide-related sequence A/B (MICA/B)] on the membrane and the soluble form of MICA was evaluated using flow cytometry and ELISA. Cytotoxicity assay was performed using GFP-transfected K562 cells as target cells. E2 reduced NKL cell-mediated cytotoxicity, while PRL exerted the opposite effect. NKL cells expressed different hormone receptor forms, of which PRL only induced a decrease in NKG2D expression compared to the untreated control NKL cells. PRL increased MICA/B expression in HeLa cells and E2 and PRL reversed this effect. However, in SiHa cells, the concurrent incubation with the two hormones decreased MICA/B expression. E2 and PRL, either alone or in combination, decreased soluble MICA secretion in all CC cell lines, while E2 solely increased soluble MICA secretion in SiHa cells. On the whole, the present study provides evidence that E2 and PRL mediate the mechanisms through which NK and CC cells mediate a cytotoxic response and these have an antagonistic effect on NK cell-mediated cytotoxicity.     

NKG2D 介导CIK 细胞对食管癌EC9706细胞杀伤作用的体外研究*

目的:研究细胞因子诱导的杀伤细胞（Cytokine-induced killer cells ,CIK）对食管癌EC9706细胞株的体外杀伤活性。方法:流式细胞仪检测EC9706细胞NKG2D 配体的表达;体外分离健康者外周血单个核细胞,干扰素-γ 、白细胞介素-2、CD3 单抗诱导培养,流式细胞仪检测 0、14天的细胞 CD3+CD56+、NKG2D 的表达,乳酸脱氢酶释放法测定培养14天的 CIK 细胞在效靶比 10 :1、2 0 :1、3 0 :1、4 0 :1、5 0 :1 时对EC9706细胞的杀伤活性;效靶比3 0 :1 时,观察NKG2D 单抗封闭CIK 细胞表面NKG2D 分子后对CIK细胞杀伤活性的影响。结果:EC9706细胞表达MICA、ULBP2,不表达MICB、ULBP1、ULBP3。0、14天细胞表面NKG2D 表达率分别为（26.30± 1.12）% 、（67.13± 1.34）% ,差异有统计学意义（P<0.05）;CD3+CD56+细胞分别为（0.68± 0.07）% ,（56.55± 2.01）% ,差异有统计学意义（P<0.05）;效靶比1 0 :1、2 0 :1、3 0 :1、4 0 :1、5 0 :1 时CIK 细胞对EC9706细胞的杀伤活性分别为（28.81± 0.47）% 、（37.78±0.22）%、（44.31± 1.06）%、（47.25± 0.47）%、（57.62± 0.94）%;随着效靶比增高,CIK 细胞对 EC9706细胞的杀伤活性明显增强（P<0.05）;效靶比3 0 :1 时NKG2D 单抗封闭CIK 细胞表面NKG2D 分子后,CIK 细胞对EC9706细胞的杀伤活性为（30.29± 1.45）% ,与阻断前（44.31± 1.06）% 相比差异有统计学意义（P<0.05）。 结论:体外CIK 细胞培养增殖过程中,NKG2D 分子表达逐渐上调,CD3+CD56+细胞逐渐增多,CIK 细胞杀伤EC9706细胞通过NKG2D 发挥作用。      

Novel role for STAT3 in transcriptional regulation of NK immune cell targeting receptor MICA on cancer cells

The role of natural killer group 2, member D receptor (NKG2D)-expressing natural killer (NK) cells in tumor immunosurveillance is now well established. Nevertheless, tumor progression occurs despite tumor immunosurveillance, leading to cancer persistence in immunocompetent hosts. STAT3 plays a pivotal role both in oncogenic functions and in immunosuppression. In this study, we investigated the role of STAT3 in suppressing NK cell-mediated immunosurveillance. Using a colorectal cancer cell line (HT29) that can poorly activate NK, we neutralized STAT3 with pharmacologic inhibitors or siRNA and found that this led to an increase in NK degranulation and IFN-γ production in a TGF-β1-independent manner. Exposure to NKG2D-neutralizing antibodies partially restored STAT3 activity, suggesting that it prevented NKG2D-mediated NK cell activation. On this basis, we investigated the expression of NKG2D ligands after STAT3 activation in HT29, mesenchymal stem cells, and activated lymphocytes. The NK cell recognition receptor MHC class I chain-related protein A (MICA) was upregulated following STAT3 neutralization, and a direct interaction between STAT3 and the MICA promoter was identified. Because cross-talk between DNA damage repair and NKG2D ligand expression has been shown, we assessed the influence of STAT3 on MICA expression under conditions of genotoxic stress. We found that STAT3 negatively regulated MICA expression after irradiation or heat shock, including in lymphocytes activated by CD3/CD28 ligation. Together, our findings reveal a novel role for STAT3 in NK cell immunosurveillance by modulating the MICA expression in cancer cells.     

Generation of antitumor responses by genetic modification of primary human T cells with a chimeric NKG2D receptor

To create more effective T cells against human tumors, we have designed a strategy to allow T cells to recognize tumor cells using natural killer (NK) cell receptors but retain the effector responses of T lymphocytes. NKG2D is an activating cell surface receptor expressed on NK cells and on some T-cell subsets. Its ligands are primarily expressed on tumor cells. We have shown that by linking mouse NKG2D to the CD3zeta chain, it was possible to generate a chimeric NKG2D (chNKG2D) receptor that allowed activation of murine T cells on engagement with NKG2D ligand-positive tumor cells leading to antitumor responses in mice. In this study, a human version of the chNKG2D receptor was expressed on primary human T cells, and antitumor responses were determined. Human peripheral blood mononuclear cell-derived T cells were retrovirally transduced with a human chNKG2D receptor gene. These chNKG2D-bearing human T cells responded to NKG2D ligand-positive tumor cells by producing T-helper 1 cytokines, proinflammatory chemokines, and significant cellular cytotoxicity. This response could be blocked by anti-NKG2D antibodies, and it was dependent on NKG2D ligand expression on the target cells but not on expression of MHC molecules. In addition, the activity of chNKG2D-bearing T cells remained unimpaired after exposure to a soluble NKG2D ligand, soluble MICA, at concentrations as high as 1.5 mug/mL. These data indicate the feasibility of using chNKG2D receptors in primary human T cells and suggest that this approach may be a promising means for cancer immunotherapy.     

Sodium valproate, a histone deacetylase inhibitor, augments the expression of cell-surface NKG2D ligands, MICA/B, without increasing their soluble forms to enhance susceptibility of human osteosarcoma cells to NK cell-mediated cytotoxicity

MHC class I-related chain molecules A and B (MICA and B) expressed on the cell-surface of tumor cells are ligands for an activating receptor, NKG2D, expressed on natural killer (NK) cells and stimulate the NK cell-mediated cytotoxicity. On the other hand, the soluble form of MICA and B produced by proteolytic cleavage of cell-surface MIC interferes with NK cell-mediated cytotoxicity. We investigated effect of sodium valproate (VPA), a histone deacetylase inhibitor, on the production of cell-surface and soluble MICA and B and NK cell-mediated cytotoxicity in four human osteosarcoma cells. VPA at 0.5 and 1.0 mM induced acetylation of histones bound to MICA and B gene promoters, increased cell-surface but not soluble MICA and B, and augmented the susceptibility of osteosarcoma cells to NK cell-mediated cytotoxicity. The present results indicate that VPA sensitizes human osteosarcoma cells to cytotoxicity of NK cells.     

Major histocompatibility complex class I-related chain A and UL16-binding protein expression on tumor cell lines of different histotypes: analysis of tumor susceptibility to NKG2D-dependent natural killer cell cytotoxicity

NKG2D, together with NKp46 and NKp30, represents a major triggering receptor involved in the induction of cytotoxicity by both resting and activated human natural killer cells. In this study, we analyzed the expression and the functional relevance of MHC class I-related chain A (MICA) and UL16 binding protein (ULBP), the major cellular ligands for human NKG2D, in human tumor cell lines of different histological origin. We show that MICA and ULBP are frequently coexpressed by carcinoma cell lines, whereas MICA is expressed more frequently than ULBP by melanoma cell lines. Interestingly, the MICA(-) ULBP(+) phenotype was detected in most T cell leukemia cell lines, whereas the MICA(-) ULBP(-) phenotype characterized all acute myeloid leukemia and most B-cell lymphoma cell lines analyzed. These results, together with functional experiments, based on monoclonal antibody-mediated blocking of either NKG2D or its ligands, showed that killing of certain MICA(-) cell tumors is at least in part NKG2D dependent. Indeed, leukemic T cells as well as certain B-cell lymphomas were killed in a NKG2D-dependent fashion upon recognition of ULBP molecules. Moreover, ULBP could induce NKG2D-mediated NK cell triggering also in tumors coexpressing MICA. Our data suggest that the involvement of NKG2D in natural killer cell-mediated cytotoxicity strictly correlates with the expression and the surface density of MICA and ULBP on target cell tumors of different histotypes.     

厄洛替尼增强肺腺癌A549细胞对CIK细胞杀伤的敏感性

  目的  研究表皮生长因子受体酪氨酸激酶抑制剂厄洛替尼对人肺腺癌A549 细胞NKG2D配体表达及CIK细胞杀伤活性的影响及其分子机制。  方法  流式细胞仪检测厄洛替尼、EGFR下游分子LY294002（PI3K抑制剂）、SB203580（MAPK抑制剂）、STAT21（STAT3抑制剂）作用A549细胞24 h后A549细胞NKG2D配体的表达。乳酸脱氢酶释放法测定不同效靶比时,CIK细胞对10 μmol/L厄洛替尼作用前、后A549细胞的杀伤活性。  结果  厄洛替尼下调A549细胞MICA表达,上调MICB、ULBP1表达,EGFR下游分子 MAPK、STAT3 抑制剂不影响 A549 细胞 NKG2D 配体的表达,PI3-K 抑制剂下调 A549 细胞 MICA 表达,厄洛替尼增强A549细胞对CIK细胞杀伤的敏感性。  结论  EGFR TKI 抗肺癌作用与其增强肺癌细胞对免疫细胞杀伤的敏感性有关。      

IL-15上调NKG2D表达对CIK细胞杀伤活性的增强效应

目的观察IL-15对细胞因子诱导的杀伤细胞( Cytokine-induced killer cells,CIK)NKG2D受体表达及其对食管癌EC9706细胞杀伤活性的影响。方法体外分离外周血单个核细胞,分为两组。对照组：干扰素-γ、白细胞介素-2、CD3单抗诱导培养CIK细胞。IL-15组：加用IL-15培养。流式细胞仪检测细胞免疫表型及CD3+细胞、CD56+细胞表面NKG2D的表达,LDH法测定第14天细胞在效靶比20∶1、30∶1时对EC9706细胞的杀伤活性;效靶比30∶1时,观察NKG2D单抗封闭细胞表面NKG2D分子后对两组细胞杀伤活性的影响。结果随着培养时间的延长,CIK群体细胞及CD56+细胞表面NKG2D表达逐渐增强,IL-15组与对照组相比差异有统计学意义(P＜0.05);效靶比20∶1、30∶1时,IL-15组细胞对EC9706细胞的杀伤活性均较对照组明显增强,差异均有统计学意义(P＜0.05);效靶比30∶1时NKG2D单抗封闭CIK细胞表面NKG2D分子后,对照组细胞、IL-15组细胞对EC9706细胞的杀伤活性均较阻断前明显下降,差异均有统计学意义 (P＜0.05)。结论IL-15上调CIK细胞表面NKG2D分子表达,增强CIK细胞对EC9706细胞的杀伤活性,CIK细胞通过NKG2D发挥作用。     

NKG2D介导NK 细胞对鼻咽癌细胞杀伤作用的体外研究

 目的 探讨鼻咽癌CNE2细胞表面HLA-Ⅰ类分子表型和NKG2D配体的表达情况，进一步了解其对同种异体NK细胞杀伤活性的影响。方法 流式细胞仪检测NKG2D的配体MICA、MICB、ULBP1、ULBP2、ULBP3在K562、CNE2细胞的表达情况。PCR-SSP法分析CNE2细胞HLA-A、B、Cw分型和NK细胞KIR分型。LDH释放法测定5例健康者NK细胞在不同效靶比时对K562、CNE2细胞的杀伤活性，效靶比20：1时观察抗NKG2D配体的单抗对NK细胞杀伤K562、CNE2细胞活性的影响。结果 CNE2细胞表达MICA、MICB、ULBP2，不表达ULBP1、ULBP3。K562细胞表面表达MICA、MICB、ULBP1、ULBP2、ULBP3。5例健康者NK细胞抑制性KIR与CNE2细胞表面的HLA-Ⅰ类分子之间存在错配。效靶比5：1、10：1、20：1、30：1时NK细胞对K562、CNE2细胞的杀伤活性分别为（29．02±0．45）％、（10．50±2．17）％；（44．43±1．36）％、（27．68±1．47）％；（57．82±1．35）％、（36．99±3．13）％：（71．24±2．36）％、（55．00±2．20）％，在各效靶比时NK细胞对K562细胞的杀伤活性较CNE2细胞明显增强（P=0．000）；在效靶比20：1时anti-MICA、anti-MICB、anti-ULBP1、anti—ULBP2、anti-ULBP3可明显抑制NK细胞对K562细胞的杀伤活性，与阻断前相比有显著性差异（P=0．000）；anti—MICA、anti—MICB、anti—ULBP2可明显抑制NK细胞对CNE2细胞的杀伤活性，与阻断前相比有显著性差异（P〈0．01），但anti—ULBP1、anti—ULBP3不能阻断NK细胞对CNE2细胞的杀伤活性。结论 NKG2D配体影响NK细胞对靶细胞的杀伤活性，提高NKG2D配体的表达有可能提高NK细胞的抗肿瘤活性。     

The requirement for DNAM-1, NKG2D, and NKp46 in the natural killer cell-mediated killing of myeloma cells

Recent evidence suggests a role for natural killer (NK) cells in the control of multiple myeloma. We show that expression of the NK cell receptor DNAM-1 (CD226) is reduced on CD56(dim) NK cells from myeloma patients with active disease compared with patients in remission and healthy controls. This suggested that this receptor might play a role in NK-myeloma interactions. The DNAM-1 ligands Nectin-2 (CD112) and the poliovirus receptor (PVR; CD155) were expressed by most patient myeloma samples analyzed. NK killing of patient-derived myelomas expressing PVR and/or Nectin-2 was DNAM-1 dependent, revealing a functional role for DNAM-1 in myeloma cell killing. In myeloma cell lines, cell surface expression of PVR was associated with low levels of NKG2D ligands, whereas cells expressing high levels of NKG2D ligands did not express PVR protein or mRNA. Furthermore, NK cell-mediated killing of myeloma cell lines was dependent on either DNAM-1 or NKG2D but not both molecules. In contrast, the natural cytotoxicity receptor NKp46 was required for the killing of all myeloma cell lines analyzed. Thus, DNAM-1 is important in the NK cell-mediated killing of myeloma cells expressing the cognate ligands. The importance of NKp46, NKG2D, and DNAM-1 in myeloma killing mirrors the differential expression of NK cell ligands by myeloma cells, reflecting immune selection during myeloma disease progression.     

Proteolytic release of soluble UL16-binding protein 2 from tumor cells

The MHC class I-related ligands of the immunoreceptor NKG2D are frequently expressed by tumor cells and stimulate tumor immunity mediated by CD8 T cells and natural killer (NK) cells. In humans, NKG2D ligands (NKG2DL) are encoded by the MHC-encoded MIC and non-MHC-encoded UL16-binding protein (ULBP) families of proteins. Recently, we and others showed that tumor cells release soluble MICA (sMICA), thereby counteracting NKG2D-mediated tumor immunosurveillance. Here, we now report that ULBP2 molecules are likewise released from tumor cells in a processed soluble form, and that soluble ULBP2 (sULBP2) can be detected in sera of some patients with hematopoietic malignancies. Tumor cell-derived sULBP2 as opposed to cell-bound ULBP2 does not down-regulate NKG2D on NK cells. Unexpectedly, the glycosylphosphatidylinositol-anchored ULBP2 molecules are not released by phospholipases but by the action of metalloproteases. Proteolytic shedding of both NKG2D ligands MICA and ULBP2 by tumor cells was strongly enhanced after phorbol 12-myristate 13-acetate treatment and paralleled by a markedly reduced susceptibility to NKG2D-mediated cytotoxicity. Shedding of MICA and ULBP2 can be blocked by the same inhibitors, suggesting the involvement of related metalloproteases. Thus, our data suggest that reducing NKG2DL surface densities is due to a common cleavage process executed by metalloproteases that promotes escape of tumors from NKG2D-mediated immunosurveillance.     

Ataxia–telangiectasia mutated kinase‐mediated upregulation of NKG2D ligands on leukemia cells by resveratrol results in enhanced natural killer cell susceptibility

The powerful activating receptor NKG2D is expressed by natural killer (NK) cells and promotes cytotoxic lysis of cancer cells expressing NKG2D ligands (NKG2D‐Ls). We report the effective induction of NKG2D‐Ls, achieved with the naturally occurring polyphenol resveratrol, in a broad range of leukemia cells. In this study, resveratrol upregulated the NKG2D‐Ls MHC class I chain‐related proteins MICA and MICB, and UL16‐binding proteins ULBP1, ULBP2, and ULBP3 in most of the leukemia cells analyzed. Ligand upregulation induced by resveratrol was impaired by pharmacological and genetic disruption of ataxia–telangiectasia mutated kinase, the main regulator of NKG2D‐L expression. Leukemia cells treated with resveratrol were more susceptible to killing by NK cells than untreated cells, and the enhanced cytotoxicity of NK cells was blocked by treatment of NK cells with anti‐NKG2D mAbs. Interestingly, resveratrol consistently upregulated the NKG2D receptor expression and enhanced NKG2D‐mediated functions in resting NK cells obtained from healthy individuals. Therefore, resveratrol has attractive immunotherapeutic potential.     

顺铂对鼻咽癌细胞NKG2D配体表达和NK细胞杀伤活性的增强作用

 目的 研究顺铂(Cisplatin, DDP)作用前后人鼻咽癌细胞CNE2 NKG2D配体和HLA-Ⅰ类分子表达的改变及NK细胞杀伤活性的变化。 方法 MTT法测定DDP对CNE2细胞的50%抑制量（IC₅₀）;以此浓度DDP作用CNE2细胞24h,乳酸脱氢酶释放法检测效靶比20∶1时,NK细胞对DDP作用前后的CNE2细胞的杀伤活性;流式细胞仪检测DDP作用前后的CNE2细胞表面NKG2D配体(MICA/B、ULBP1、ULBP2、 ULBP3)和HLA-Ⅰ类分子表达的变化。 结果 DDP对CNE2细胞的IC₅₀为5mg/L。效靶比20∶1时,NK细胞对5mg/L DDP作用前后的CNE2细胞的杀伤活性分别为 （38.11±1.41）%,（47.71±1.53）%,差异有统计学意义（P＜0.05）,DDP作用后CNE2细胞表面MICA/B、ULBP1、 ULBP3表达显著升高,与作用前相比差异有统计学意义（P＜0.05）。ULBP2、HLA-Ⅰ类分子无明显变化(P＞0.05)。 结论 DDP能提高CNE2细胞NKG2D配体(MICA/B、ULBP1、ULBP3)的表达,从而增强CNE2细胞对NK细胞杀伤的敏感度。