Switch of HLA-G alternative splicing in a melanoma cell line causes loss of HLA-G1 expression and sensitivity to NK lysis

Considerable information has been accumulated on HLA-G expression in tumor lesions in which HLA-G is viewed as a way to turn off anti-tumoral immunity. Nevertheless, there is little data concerning the mechanisms by which expression and function of HLA-G are regulated in malignant cells. Here, we have addressed these points by studying a melanoma cell line derived from a surgically-removed HLA-G-positive melanoma lesion. We show that HLA-G expression in melanoma cells can be regulated at the mRNA splicing level. Indeed, melanoma cells rapidly switched from cell-surface HLA-G1 to intra-cellular HLA-G2 expression. This mechanism restored tumor sensitivity to NK lysis. Moreover, switch from HLA-G1 to HLA-G2 was strong enough to prevent re-expression of immunoprotective HLA-G1 even following treatments with cytokines and DNA demethylating agent. Modulating HLA-G at the mRNA splicing level would be an efficient way of lifting in vivo HLA-G-mediated tumor immune escape.     

ASK1 suppresses NK cell-mediated intravascular tumor cell clearance in lung metastasis

Tumor metastasis is the leading cause of death worldwide and involves an extremely complex process composed of multiple steps. Our previous study demonstrated that apoptosis signal-regulating kinase 1 (ASK1) deficiency in mice attenuates tumor metastasis in an experimental lung metastasis model. However, the steps of tumor metastasis regulated by ASK1 remain unclear. Here, we showed that ASK1 deficiency in mice promotes natural killer (NK) cell-mediated intravascular tumor cell clearance in the initial hours of metastasis. In response to tumor inoculation, ASK1 deficiency upregulated immune response-related genes, including interferon-gamma (IFNγ). We also revealed that NK cells are required for these anti-metastatic phenotypes. ASK1 deficiency augmented cytokine production chemoattractive to NK cells possibly through induction of the ligand for NKG2D, a key activating receptor of NK cells, leading to further recruitment of NK cells into the lung. These results indicate that ASK1 negatively regulates NK cell-dependent anti-tumor immunity and that ASK1-targeted therapy can provide a new tool for cancer immunotherapy to overcome tumor metastasis.     

Programmed cell death 1‐expressing CD56‐negative natural killer (NK) cell expansion is a hallmark of chronic NK cell activation during dasatinib treatment

Dasatinib treatment markedly increases the number of large granular lymphocytes including natural killer (NK) cells in a proportion of Ph⁺ leukemia patients, which associates with a better prognosis. In‐depth immune profiling of NK cells can predict therapeutic response in these patients. In the present study, we showed that CD56‐negative (CD56^neg) NK cells increased exclusively in cytomegalovirus‐seropositive (CMV⁺) patients treated with dasatinib. The increase longitudinally paralleled with progressive differentiation of CD56^dim NK cells during dasatinib therapy driven by CMV reactivation as shown by principal component analysis on 19 NK cell markers. The CD56^neg NK cells showed downregulation of NK‐activating receptors, upregulation of PD‐1, and lower cytotoxicity and cytokine production, indicating that these cells are anergic and dysfunctional as seen in chronic infections with HIV‐1 or hepatitis C virus. Moreover, cytolytic activity of CD56^dim and CD56^neg NK cells against leukemia cells was partially restored by nivolumab in proportion to the frequency of PD‐1⁺ NK cells. The proportion of patients who achieved deep molecular responses at 2 years was significantly higher in dasatinib‐treated patients with ≥3% CD56^neg NK cells than in those with fewer CD56^neg NK cells (54.5% vs 15.8%, P = .0419). These findings suggest that CD56^neg NK cells may be an exhausted population induced by chronic activation through CMV reactivation during dasatinib therapy. Expansion of CD56^neg NK cells is a hallmark of chronic NK cell activation in patients treated with dasatinib and may predict a better clinical outcome. Furthermore, PD‐1 blockade may enhance anti‐leukemia responses of such NK cells.     

HLA-G expression is associated with metastasis and poor survival in the Balb/c nu/nu murine tumor model with ovarian cancer

Aberrant HLA-G expression is associated with tumor invasiveness and poor clinical prognosis; however, there is a lack of preclinical animal model to address whether HLA-G plays a causal role in the unfavorable prognosis of malignancies. In the current study, ovarian carcinoma cell lines (HO-8910 and Ovcar-3) were transfected with HLA-G gene. HLA-G expression was analyzed with western blot and flow cytometry. Transwell experiment was performed to analyze the cell migration and invasion capability and/or multicellular spheroid formation was investigated with the 3D culture assay in vitro. The effects of HLA-G expression for tumor cell organ metastasis and for mouse survival was analyzed with the Balb/c nu/nu mouse model. Our data showed that HO-8910-G and Ovcar-3-G cells are of higher invasion potential compared with the parental HO-8910 and Ovcar-3 cells. Multicellular spheroid formation exists only in HO-8910-G cells in a 3D culture assay. In Balb/c nu/nu mouse model, widespread metastasis was observed in mice xenografted with HO-8910-G cells, but not in the group with parental cells. Mouse survival was dramatically decreased in HO-8910-G and Ovcar-3-G xenografted mice than that with HO-8910 and Ovcar-3 cells, respectively. In summary, our study provided the first evidence that HLA-G expression is associated with tumor metastasis and with poor survival in an animal model with ovarian cancer.     

Tumor cell expression of immune inhibitory molecules and tumor‐infiltrating lymphocyte count predict cancer‐specific survival in pancreatic and ampullary cancer

Understanding the mechanisms of immune resistance in pancreatic and ampullary cancers is crucial for the development of suitable biomarkers and effective immunotherapeutics. Our aim was to examine the expression of the immune inhibiting molecules PD‐L1, Galectin‐9, HVEM, IDO and HLA‐G, as well as CD8+ and FoxP3+ tumor infiltrating lymphocytes (TIL), in pancreatic and ampullary cancers, and to relate their individual, as well as their combined expression, to cancer survival. Tumor tissue from 224 patients with resected pancreatic (n = 148) and ampullary (n = 76) cancer was used to construct tissue‐microarrays. Expression of immune inhibitory molecules and TIL was examined by immunohistochemistry. We show that immune inhibitory molecules are prevalently expressed. Moreover, high tumor expression of PD‐L1 (p = 0.002), Gal‐9 (p = 0.003), HVEM (p = 0.001), IDO (p = 0.049), HLA‐G (p = 0.004) and high CD8/FoxP3 TIL ratio (p = 0.006) were associated with improved cancer‐specific survival. All immune biomarkers, with the exception of IDO, were individually predictive of cancer‐specific survival when adjusted for clinicopathologic characteristics. For every additional immune biomarker present survival was almost two‐fold prolonged (HR 0.57 95%CI 0.47–0.69, p < 0.0001). When patients with pancreatic and ampullary cancer were analyzed separately the results were similar. We conclude that pancreas and ampullary cancers are rich in expression of immune‐inhibitory molecules. These molecules can be targets for future immunotherapeutics, as well as form powerful immunological biomarkers. We propose that such immune biomarker panels be included in future prospective immunotherapy trials.     

GCIP functions as a tumor suppressor in non-small cell lung cancer by suppressing Id1-mediated tumor promotion

Grap2 and cyclin D1 interacting protein (GCIP) has been recognized as a putative tumor suppressor, but the molecular mechanisms underlying its anti-tumor properties remain undefined. Here, we report that GCIP is frequently downregulated in non-small cell lung cancer (NSCLC) tissues. Binding assays indicated that inhibitor of DNA binding/differentiation 1 (Id1) interacts with GCIP in the nucleus. Ectopic GCIP expression in the highly invasive NSCLC cell line, H1299, inhibited proliferation, colony formation, invasion and migration, and increased susceptibility to anticancer drugs. Conversely, silencing GCIP expression in the minimally invasive NSCLS cell line, A549, increased proliferation, colony formation, invasion, and migration in vitro, and increased survival and resistance to anticancer drugs. GCIP also suppresses tumorigenicity of NSCLC cells in vivo and GCIP suppresses NSCLC progression is mediated in part by interfering with Id1 signaling, which was confirmed in conditionally induced stable cell lines. In addition, GCIP downregulates the expression of Id1, and GCIP and Id1 are inversely expressed in NSCLC cell lines and specimens. Taken together, these results suggest that GCIP is a potential tumor suppressor in NSCLC and that suppression of Id1-mediated oncogenic properties may be a key mechanism by which GCIP can potently suppress NSCLC tumor progression.     

Reversal of tumor acidosis by systemic buffering reactivates NK cells to express IFN‐γ and induces NK cell‐dependent lymphoma control without other immunotherapies

Like other immune cells, natural killer (NK) cells show impaired effector functions in the microenvironment of tumors, but little is known on the underlying mechanisms. Since lactate acidosis, a hallmark of malignant tissue, was shown to contribute to suppression of effective antitumor immune responses, we investigated the impact of tissue pH and lactate concentration on NK‐cell functions in an aggressive model of endogenously arising B‐cell lymphoma. The progressive loss of IFN‐γ production by NK cells observed during development of this disease could be ascribed to decreased pH values and lactate accumulation in the microenvironment of growing tumors. Interestingly, IFN‐γ expression by lymphoma‐derived NK cells could be restored by transfer of these cells into a normal micromilieu. Likewise, systemic alkalization by oral delivery of bicarbonate to lymphoma‐developing mice was capable of enhancing IFN‐γ expression in NK cells and increasing the NK‐cell numbers in the lymphoid organs where tumors were growing. By contrast, NK‐cell cytotoxicity was dampened in vivo by tumor‐dependent mechanisms that seemed to be different from lactate acidosis and could not be restored in a normal milieu. Most importantly, alkalization and the concomitant IFN‐γ upregulation in NK cells were sufficient to significantly delay tumor growth without any other immunotherapy. This effect was strictly dependent on NK cells.     

Mutant IDH1 is required for IDH1 mutated tumor cell growth

Frequent somatic hotspot mutations in isocitrate dehydrogenase 1 (IDH1) have been identified in gliomas, acute myeloid leukemias, chondrosarcomas, and other cancers, providing a likely avenue for targeted cancer therapy. However, whether mutant IDH1 protein is required for maintaining IDH1 mutated tumor cell growth remains unknown. Here, using a genetically engineered inducible system, we report that selective suppression of endogenous mutant IDH1 expression in HT1080, a fibrosarcoma cell line with a native IDH1R132C heterozygous mutation, significantly inhibits cell proliferation and decreases clonogenic potential. Our findings offer insights into changes that may contribute to the inhibition of cell proliferation and offer a strong preclinical rationale for utilizing mutant IDH1 as a valid therapeutic target.     

黏蛋白1多肽通过small-MUC1蛋白抑制肿瘤细胞生长

目的：探讨黏蛋白1（mucin 1,MUC1）串联重复序列多肽(简称黏蛋白1多肽,MUC1多肽)对肿瘤细胞生长抑制的作用机制。方法：MUC1多肽与多种肿瘤细胞Jurkat、Raji、U937、MCF7、SMMC7721及活化的T细胞、小鼠巨噬细胞RAW264.7共同培养,观察MUC1多肽对上述细胞生长的影响;建立BABL/c小鼠Jurkat细胞皮下移植瘤动物模型,应用MUC1多肽进行治疗;采用GST免疫沉降实验鉴定与MUC1多肽结合的肿瘤细胞表面蛋白。结果：MUC1多肽对Jurkat、Raji、U937、MCF7和SMMC7721细胞的生长均有抑制作用,对活化的T细胞和小鼠RAW264.7细胞生长无明显抑制作用。MUC1多肽对BABL/c小鼠皮下Jurkat细胞移植瘤的生长均有明显抑制作用（P<0.05）。GST免疫沉降实验显示,Jurkat 和MCF7细胞裂解上清中与MUC1多肽结合的蛋白可与两种抗MUC1串联重复序列抗体（GP1.4和HMPV）及抗胞内段抗体（Ab5）发生反应,相对分子质量大约115 000,提示可能是MUC1新的同种型,命名为small MUC1（sMUC1）。结论：MUC1多肽可通过与肿瘤细胞表面small MUC1蛋白的相互作用向细胞传导生长抑制信号     

Macrophage inflammatory protein 1 alpha (MIP‐1α) may be associated with poor outcome in patients with extranodal NK/T‐cell lymphoma

The macrophage inflammatory protein 1α (MIP‐1α) is anticipated to have a role in extranodal natural killer (NK)/T‐cell lymphoma (ENKTL) because the expression of MIP‐1α is related to Epstein–Barr virus (EBV) latency in EBV‐related non‐Hodgkin lymphoma cells. Thus, we measured the serum level of MIP‐1α in 69 patients with ENKTL using frozen serum samples that were archived at diagnosis. As serum level of MIP‐1α was not detectable in 19 patients (range: 0–24.37 pg/mL), patients were dichotomized into positive (n = 50) and negative (n = 19) MIP‐1α groups according to the presence of detectable level of MIP‐1α in serum. MIP‐1α‐positive group showed a significantly poor overall survival (OS) in comparison with the MIP‐1α‐negative group (p = 0.004). In the subgroup analysis, the positivity of MIP‐1α was significantly associated with OS in patients with stage IIIE/IV and a detectable level of EBV DNA (p = 0.002 and 0.032, respectively). Multivariate analysis also showed that the positivity of MIP‐1α was independently associated with worse OS together with bone marrow involvement (p = 0.002). An in vitro study with patient‐derived ENKTL tumour cells showed the expression of CCR1 and CCR5 on the surface of tumour cells (28% and 14%, respectively) , and the addition of MIP‐1α to the culture media of tumour cells increased cell growth supporting the negative impact of MIP‐1α on the prognosis of ENKTL patients. In conclusion, serum levels of MIP‐1α could predict survival outcomes in patients with ENKTL. Therefore, MIP‐1α should be considered for prognostication and a potential therapeutic target. Copyright © 2016 John Wiley & Sons, Ltd.     

EBNA1阳性肿瘤细胞株的建立

目的：建立表达Epstein-Barr(EB)病毒核抗原-l(EBNA1)的肿瘤细胞株，用于EB病毒相关肿瘤的研究。方法：将1200bp的EBNA1基因片段插入真核细胞表达载体pcDNA3中，使用脂质体介导pcDNA3／EBNA1质粒进入人鼻咽癌CNE2细胞和人宫颈癌Hela细胞，通过G418进行阳性克隆的筛选，PCR、RT-PCR进行鉴定。结果：成功建立EBNA1基因阳性的鼻咽癌和宫颈癌肿瘤细胞株，经PCR、RT-PCR检测证明两种转基因细胞株稳定表达EBNA1。结论：EBNA1阳性肿瘤细胞株的建立，为体外进行EB病毒相关肿瘤的研究提供细胞模型：     

Anti-G-CSF treatment induces protective tumor immunity in mouse colon cancer by promoting NK cell,macrophage and T cell responses

Granulocyte colony-stimulating factor (G-CSF) is a cytokine that is highly expressed in human and mouse colorectal cancers (CRC). We previously reported that G-CSF stimulated human CRC cell growth and migration, therefore in this study we sought to examine the therapeutic potential of anti-G-CSF treatment for CRC. G-CSF is known to mobilize neutrophils, however its impact on other immune cells has not been well examined. Here, we investigated the effects of therapeutic anti-G-CSF treatment on CRC growth and anti-tumor immune responses. C57BL/6 mice treated with azoxymethane/dextran sodium sulfate (AOM/DSS) to induce neoplasms were administered anti-G-CSF or isotype control antibodies three times a week for three weeks. Animals treated with anti-G-CSF antibodies had a marked decrease in neoplasm number and size compared to the isotype control group. Colon neutrophil and macrophage frequency were unchanged, but the number of macrophages producing IL-10 were decreased while IL-12 producing macrophages were increased. NK cells were substantially increased in colons of anti-G-CSF treated mice, along with IFNγ producing CD4⁺ and CD8⁺ T cells. These studies are the first to indicate a crucial role for G-CSF inhibition in promoting protective anti-tumor immunity, and suggest that anti-G-CSF treatment is a potential therapeutic approach for CRC.     

Clinical significance of programmed death‐1 and programmed death‐ligand 1 expression in the tumor microenvironment of clear cell renal cell carcinoma

Recently, immunotherapy based on blocking immune checkpoints with programmed death‐1 (PD‐1) or PD‐ligand 1 (PD‐L1) Abs has been introduced for the treatment of advanced clear cell renal cell carcinoma (ccRCC), especially tumors resistant to vascular endothelial growth factor‐tyrosine kinase inhibitors (VEGF‐TKIs), but the significance of their expression in the tumor microenvironment is unclear. We investigated these immune checkpoint markers in tumor cells and tumor‐infiltrating immune cells (TIIC) in the tumor microenvironment of 100 untreated and 25 VEGF‐TKI‐treated primary ccRCC tissues. Upregulated expression of PD‐1 and PD‐L1 by TIIC, and PD‐L1 by tumor cells was associated with the histological grade and unfavorable prognosis of RCC patients. High PD‐1 and PD‐L1 expression by TIIC was associated with a poorer response to VEGF‐TKI, whereas PD‐L1 expression by tumor cells did not affect the efficacy of the treatment. Furthermore, increased PD‐1‐positive TIIC and PD‐L1‐positive TIIC were observed in tumors treated with VEGF‐TKIs compared with those in untreated tumors. Our data suggest that PD‐1 and PD‐L1 expression by TIIC in the tumor microenvironment is involved in treatment resistance, and that sequential therapy with immune checkpoint inhibitors could be a promising therapeutic strategy for ccRCC resistant to VEGF‐TKI treatment.     

Efficient tumor cell lysis by autologous,tumor-resident T lymphocytes in primary ovarian cancer samples by an EP-CAM-/CD3-bispecific antibody

The epithelial cell adhesion molecule (Ep-CAM) is expressed on the surface of most human carcinomas, including ovarian, breast, lung, prostate and colorectal carcinoma. Ep-CAM was shown to be a valid target for monoclonal antibody-based therapies. We have investigated whether an Ep-CAM-/CD3-bispecific single-chain antibody called bscEp-CAM x CD3 is effective in tumor cell elimination within the cellular microenvironment of primary ovarian cancer tissue. The ex vivo elimination of ovarian cancer cells in tumor preparations from 21 patients was monitored by flow cytometry using Ep-CAM/CA-125 double-labeling or Ep-CAM single-labeling combined with propidium iodide uptake of cells. Methodology was established by the ovarian cancer cell line OvCAR. A total of 17 (81%) patient samples showed a dose-dependent tumor cell elimination by bscEp-CAM x CD3. High and specific tumor cell lysis was seen at bscEp-CAM x CD3 concentrations as low as 1 ng/ml, at very low effector:target ratios and in the absence of T cell costimulation. The high efficacy of the bispecific antibody may be due to the non-restricted activation of tumor-resident cytotoxic T lymphocytes. In clinical trials, the ex vivo data with the T cell-recruiting bispecific antibody bscEp-CAM x CD3 may translate into a high response rate and efficacy of tumor cell elimination.     

Simultaneous targeting of IL2 and IL12 to Hodgkin's lymphoma cells enhances activation of resting NK cells and tumor cell lysis

Hodgkin's disease (HD) is characterized by the accumulation of functionally anergic T cells in the vicinity of the malignant Hodgkin/Reed-Sternberg (H/RS) cells. To revert cellular anergy against H/RS cells, we generated an anti-CD30-antibody-interleukin-(IL)-2 and an anti-CD30-antibody-IL12 fusion protein that target IL2 and IL12, respectively, specifically to CD30+ H/RS cells. Both antibody-cytokine fusion proteins act cooperatively in the activation of resting NK cells, the induction of IFN-g gamma secretion and enhanced target cell lysis. The cooperative activity of the targeted cytokines suggests that the application of both antibody-cytokine fusion proteins may be particularly suitable for the specific immunotherapy of Hodgkin's lymphoma.     

ZPR1 is an immunodiagnostic biomarker and promotes tumor progression in esophageal squamous cell carcinoma

To evaluate the potential of zinc finger protein 1 (ZPR1) as a diagnostic biomarker and explore the underlying role for esophageal squamous cell carcinoma (ESCC). A human proteome microarray was customized to identify anti-ZPR1 autoantibody, and enzyme-linked immunosorbent assay (ELISA) was adopted to assess the diagnostic performance of anti-ZPR1 autoantibody in 294 patients with ESCC and 294 normal controls. The expression of ZPR1 protein was measured by immunohistochemistry. The effect of ZPR1 on the proliferation, migration, and invasion of ESCC cells was investigated through CCK-8, wound healing, and Transwell assays. The expression level of anti-ZPR1 autoantibody (fold change = 2.77) in ESCC patients was higher than that in normal controls. The receiver operating characteristic (ROC) analysis manifested anti-ZPR1 autoantibody achieved area under the ROC curve (AUC) of 0.726 and 0.734 to distinguish ESCC from normal controls with sensitivity of 50.0% and 42.3%, and specificity of 91.0% and 92.0% in the test group and validation group, respectively. The positive rate of ZPR1 protein was significantly higher in ESCC tissues (75.5%, 80/106) than paracancerous tissues (9.4%, 5/53). Compared with the human normal esophageal cell line, the expression level of ZPR1 mRNA and protein in ESCC lines (KYSE150, Eca109, and TE1) had an increased trend. The knockdown or overexpression of ZPR1 reduced and enhanced the proliferation, migration, and invasion of ESCC cell, respectively. ZPR1 was a potential immunodiagnostic biomarker for noninvasive detection and could be a promotional factor in tumor progression of ESCC.