MICB

Gene Summary

Gene:MICB; MHC class I polypeptide-related sequence B
Aliases: PERB11.2
Location:6p21.33
Summary:This gene encodes a heavily glycosylated protein which is a ligand for the NKG2D type II receptor. Binding of the ligand activates the cytolytic response of natural killer (NK) cells, CD8 alphabeta T cells, and gammadelta T cells which express the receptor. This protein is stress-induced and is similar to MHC class I molecules; however, it does not associate with beta-2-microglobulin or bind peptides. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2014]
Databases:IMGT/GENE-DB (MICB), OMIM, VEGA, Ensembl, HGNC, GeneCard, Gene
Protein:MHC class I polypeptide-related sequence B
Source:NCBIAccessed: 16 March, 2017

Ontology:

What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 16 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Cancer Gene Expression Regulation
  • Down-Regulation
  • Pancreatic Cancer
  • Pharmacogenetics
  • RTPCR
  • Cell Proliferation
  • Hepatocellular Carcinoma
  • Cytotoxicity, Immunologic
  • Intercellular Signaling Peptides and Proteins
  • NK Cell Lectin-Like Receptor Subfamily K
  • GPI-Linked Proteins
  • Messenger RNA
  • Flow Cytometry
  • Promoter Regions
  • Chromosome 6
  • Up-Regulation
  • Immunotherapy
  • Alleles
  • Ligands
  • Histone Deacetylase Inhibitors
  • Xenograft Models
  • Lymphocyte Activation
  • Receptors, Natural Killer Cell
  • T-Lymphocytes
  • Antineoplastic Agents
  • Signal Transduction
  • Mice, Inbred NOD
  • Gene Expression
  • Membrane Proteins
  • Natural Killer Cells
  • Young Adult
  • Histocompatibility Antigens Class I
  • Type C Phospholipases
  • TNF
  • Valproic Acid
  • Swine
  • T-Lymphocytes, Cytotoxic
  • Polymerase Chain Reaction
  • Receptors, Immunologic
  • Liver Cancer
  • Cervical Cancer
Tag cloud generated 16 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: MICB (cancer-related)

Bargostavan MH, Eslami G, Esfandiari N, Shams Shahemabadi A
MMP9 Promoter Polymorphism (-1562 C/T) Does not Affect the Serum Levels of Soluble MICB and MICA in Breast Cancer.
Iran J Immunol. 2016; 13(1):45-53 [PubMed] Related Publications
BACKGROUND: The role of Matrix Metalloproteinase 9 (MMP9) in tumor invasion and progression is prominent. A single nucleotide polymorphism (SNP) in the promoter region of MMP9 (-1562 C/T) increases the transcription and expression of this gene. On the other hand, MHC class I chain-related protein A and B (MICA/B) in soluble forms may impair tumor immunogenicity by reducing Natural Killer Group 2D (NKG2D) densities on NK cells and MMP9 enzyme activity has a prominent role in shedding of MICA/B.
OBJECTIVES: To investigate the association between MMP9 (-1562 C/T) polymorphism and serum MICA/B level in breast cancer patients.
METHODS: In this case-control study, 105 patients with breast cancer and 100 healthy age-matched women were selected from Yazd hospitals, Iran. The polymorphism of MMP9 (-1562 C/T) was determined by PCR-RFLP. Concentration of MICB and MICA in the sera of breast cancer patients and healthy women were measured using ELISA method.
RESULTS: The frequency of CC, CT and TT genotypes and T allele of the MMP9 (-1562 C/T) did not show significant differences between breast cancer patients and healthy donors (p>0.05). On the other hand, the mean serum levels of MICB and MICA were significantly elevated in patients compared with healthy individuals (p<0.05). In patients with MMP9CC genotype, the mean serum MICB concentration was significantly higher than those patients with CT polymorphism (p<0.05). Although the mean of blood MICA concentration in patients with the CT genotype was higher than those patients with CC genotype, the difference was not statistically significant.
CONCLUSION: The T allele of the MMP9 (-1562 C/T) does not show a correlation with serum levels of MICA and MICB in breast cancer patients.

Ritter C, Fan K, Paulson KG, et al.
Reversal of epigenetic silencing of MHC class I chain-related protein A and B improves immune recognition of Merkel cell carcinoma.
Sci Rep. 2016; 6:21678 [PubMed] Free Access to Full Article Related Publications
Merkel cell carcinoma (MCC) is a virally associated cancer characterized by its aggressive behavior and strong immunogenicity. Both viral infection and malignant transformation induce expression of MHC class I chain-related protein (MIC) A and B, which signal stress to cells of the immune system via Natural Killer group 2D (NKG2D) resulting in elimination of target cells. However, despite transformation and the continued presence of virally-encoded proteins, MICs are only expressed in a minority of MCC tumors in situ and are completely absent on MCC cell lines in vitro. This lack of MIC expression was due to epigenetic silencing via MIC promoter hypo-acetylation; indeed, MIC expression was re-induced by pharmacological inhibition of histone deacetylases (HDACs) both in vitro and in vivo. This re-induction of MICs rendered MCC cells more sensitive to immune-mediated lysis. Thus, epigenetic silencing of MICs is an important immune escape mechanism of MCCs.

Ribeiro CH, Kramm K, Gálvez-Jirón F, et al.
Clinical significance of tumor expression of major histocompatibility complex class I-related chains A and B (MICA/B) in gastric cancer patients.
Oncol Rep. 2016; 35(3):1309-17 [PubMed] Free Access to Full Article Related Publications
Gastric cancer (GC) is the third most common cause of cancer death worldwide. Natural killer cells play an important role in the immune defense against transformed cells. They express the activating receptor NKG2D, whose ligands belong to the MIC and ULBP/RAET family. Although it is well established that these ligands are generally expressed in tumors, the association between their expression in the tumor and gastric mucosa and clinical parameters and prognosis of GC remains to be addressed. In the present study, MICA and MICB expression was analyzed, by flow cytometry, in 23 and 20 pairs of gastric tumor and adjacent non-neoplasic gastric mucosa, respectively. Additionally, ligands expression in 13 tumors and 7 gastric mucosa samples from GC patients were evaluated by immunohistochemistry. The mRNA levels of MICA in 9 pairs of tumor and mucosa were determined by quantitative PCR. Data were associated with the clinicopathological characteristics and the patient outcome. MICA expression was observed in 57% of tumors (13/23) and 44% of mucosal samples (10/23), while MICB was detected in 50% of tumors (10/20) and 45% of mucosal tissues (9/20). At the protein level, ligand expression was significantly higher in the tumor than in the gastric mucosa. MICA mRNA levels were also increased in the tumor as compared to the mucosa. However, clinicopathological analysis indicated that, in patients with tumors >5 cm, the expression of MICA and MICB in the tumor did not differ from that of the mucosa, and tumors >5 cm showed significantly higher MICA and MICB expression than tumors ≤5 cm. Patients presenting tumors >5 cm that expressed MICA and MICB had substantially shorter survival than those with large tumors that did not express these ligands. Our results suggest that locally sustained expression of MICA and MICB in the tumor may contribute to the malignant progression of GC and that expression of these ligands predicts an unfavorable prognosis in GC patients presenting large tumors.

Miyashita T, Miki K, Kamigaki T, et al.
Low-dose gemcitabine induces major histocompatibility complex class I-related chain A/B expression and enhances an antitumor innate immune response in pancreatic cancer.
Clin Exp Med. 2017; 17(1):19-31 [PubMed] Related Publications
We investigated the effect of gemcitabine (GEM), a key drug for pancreatic cancer treatment, on the expression of cell surface MICA/B in pancreatic cancer cells and resulting cytotoxicity of γδ T cells. We assessed the effect of GEM on the upregulation of cell surface MICA/B expression by flow cytometry, utilizing six pancreatic cancer cell lines. MICA and CD16 expressions from resected pancreatic cancer patient specimens, which received neoadjuvant chemotherapy (NAC) with GEM, were analyzed by immunohistochemistry. GEM could increase MICA/B expression on cell surface in pancreatic cancer cell lines (in 2 of 6 cell lines). This effect was most effectively at concentration not affecting cell growth of GEM (0.001 μM), because MICA/B negative population was appeared at concentration at cytostatic and cytotoxic effect to cell growth (0.1 and 10 μM). The cytotoxic activity of γδ T cells against PANC-1 was detected and functions through interactions between NKG2D and MICA/B. However, the enhancement of NKG2D-dependent cytotoxicity with increased MICA/B expression, by GEM treatment, was not observed. In addition, soluble MIC molecules were released from pancreatic cancer cell lines in culture supernatant with GEM treatment. Immunohistochemical staining demonstrated that MICA expression in tumor cells and CD16 positive cells surrounding tumors were significantly higher in the NAC group compared to that of the control group. There was a significant correlation between NAC and MICA expression, as well as NAC and CD16 positive cell expression. The present results indicate that low-dose GEM-induced MICA/B expression enhances innate immune function rather than cytotoxicity in pancreatic cancer. In addition, our result suggests that the inhibition of cleavage and release of MIC molecules from the tumor surface could potentially improve NKG2D-dependent cytotoxicity.

Siew YY, Neo SY, Yew HC, et al.
Oxaliplatin regulates expression of stress ligands in ovarian cancer cells and modulates their susceptibility to natural killer cell-mediated cytotoxicity.
Int Immunol. 2015; 27(12):621-32 [PubMed] Related Publications
Selected cytotoxic chemicals can provoke the immune system to recognize and destroy malignant tumors. Most of the studies on immunogenic cell death are focused on the signals that operate on a series of receptors expressed by dendritic cells to induce tumor antigen-specific T-cell responses. Here, we explored the effects of oxaliplatin, an immunogenic cell death inducer, on the induction of stress ligands and promotion of natural killer (NK) cell-mediated cytotoxicity in human ovarian cancer cells. The results indicated that treatment of tumor cells with oxaliplatin induced the production of type I interferons and chemokines and enhanced the expression of major histocompatibility complex class I-related chains (MIC) A/B, UL16-binding protein (ULBP)-3, CD155 and TNF-related apoptosis-inducing ligand (TRAIL)-R1/R2. Furthermore, oxaliplatin but not cisplatin treatment enhanced susceptibility of ovarian cancer cells to NK cell-mediated cytolysis. In addition, activated NK cells completely abrogated the growth of cancer cells that were pretreated with oxaliplatin. However, cancer cells pretreated with the same concentration of oxaliplatin alone were capable of potentiating regrowth over a period of time. These results suggest an advantage in combining oxaliplatin and NK cell-based therapy in the treatment of ovarian cancer. Further investigation on such potential combination therapy is warranted.

Xuan XY, Zhang JF, Hu GM, et al.
Upregulated expression of NKG2D and its ligands give potential therapeutic targets for patients with thymoma.
Cancer Gene Ther. 2015; 22(7):368-74 [PubMed] Related Publications
The activating receptor NKG2D (natural killer group 2, member D) of natural killer (NK) cells promotes tumor immune surveillance by targeting ligands selectively induced on cancer cells, and thus having an important role in antitumor immune response. Because these ligands are not widely expressed on healthy adult tissue, NKG2D ligands may present as useful target for immunotherapeutic approaches in cancer. In this study, to elucidate the role of NKG2D-NKG2D ligand interaction in thymoma tissues and to evaluate the potential role of NKG2D ligands as therapeutic target for thymoma, we examined the expression of NKG2D and its specific ligands: MICA (major histocompatibility complex class I chain-related protein A), MICB (major histocompatibility complex class I chain-related protein B) and ULBP (UL16-binding protein) in 36 thymomas (6 subtype A, 6 subtype AB, 8 subtype B1, 5 subtype B2, 6 subtype B3 and 5 subtype C), 15 thymic atrophy and 8 thymic hyperplasia by immunohistochemistry and reverse transcription-real-time-PCR methods. We demonstrated that both mRNA and protein levels of NKG2D, MICA, MICB and ULBP were upregulated in six types of thymomas compared with those in atrophic thymus or proliferating thymus. Furthermore, the NKG2D ligands were found to be frequently coexpressed on thymoma cells. Furthermore, the expression of MICA, MICB and ULBP in subtype C was higher compared with those in subtype A, AB, B1, B2 and B3. Thus, we concluded that high expressions of NKG2D, MICA, MICB and ULBP1 were shown in patients with thymoma, and this may enhance the recognition function of NK cells to eliminate tumor cells. MICA, MICB and ULBP presented an attractive target for thymoma therapy. The abnormal expression of NKG2D, MICA, MICB and ULBP1 can provide us with evidence of the occurrence of thymoma and could also be used as a target in the treatment of thymoma.

Zingoni A, Cecere F, Vulpis E, et al.
Genotoxic Stress Induces Senescence-Associated ADAM10-Dependent Release of NKG2D MIC Ligands in Multiple Myeloma Cells.
J Immunol. 2015; 195(2):736-48 [PubMed] Related Publications
Genotoxic stress can promote antitumor NK cell responses by upregulating the surface expression of activating ligands on cancer cells. Moreover, a number of studies suggested a role for soluble NK group 2D ligands in the impairment of NK cell tumor recognition and killing. We investigated whether genotoxic stress could promote the release of NK group 2D ligands (MHC class I-related chain [MIC]A and MICB), as well as the molecular mechanisms underlying this event in human multiple myeloma (MM) cells. Our results show that genotoxic agents used in the therapy of MM (i.e., doxorubicin and melphalan) selectively affect the shedding of MIC molecules that are sensitive to proteolytic cleavage, whereas the release of the short MICA*008 allele, which is frequent in the white population, is not perturbed. In addition, we found that a disintegrin and metalloproteinase 10 expression is upregulated upon chemotherapeutic treatment both in patient-derived CD138(+)/CD38(+) plasma cells and in several MM cell lines, and we demonstrate a crucial role for this sheddase in the proteolytic cleavage of MIC by means of silencing and pharmacological inhibition. Interestingly, the drug-induced upregulation of a disintegrin and metalloproteinase 10 on MM cells is associated with a senescent phenotype and requires generation of reactive oxygen species. Moreover, the combined use of chemotherapeutic drugs and metalloproteinase inhibitors enhances NK cell-mediated recognition of MM cells, preserving MIC molecules on the cell surface and suggesting that targeting of metalloproteinases in conjunction with chemotherapy could be exploited for NK cell-based immunotherapeutic approaches, thus contributing to avoid the escape of malignant cells from stress-elicited immune responses.

Lanier LL
NKG2D Receptor and Its Ligands in Host Defense.
Cancer Immunol Res. 2015; 3(6):575-82 [PubMed] Free Access to Full Article Related Publications
NKG2D is an activating receptor expressed on the surface of natural killer (NK) cells, CD8(+) T cells, and subsets of CD4(+) T cells, invariant NKT cells (iNKT), and γδ T cells. In humans, NKG2D transmits signals by its association with the DAP10 adapter subunit, and in mice alternatively spliced isoforms transmit signals either using DAP10 or DAP12 adapter subunits. Although NKG2D is encoded by a highly conserved gene (KLRK1) with limited polymorphism, the receptor recognizes an extensive repertoire of ligands, encoded by at least eight genes in humans (MICA, MICB, RAET1E, RAET1G, RAET1H, RAET1I, RAET1L, and RAET1N), some with extensive allelic polymorphism. Expression of the NKG2D ligands is tightly regulated at the level of transcription, translation, and posttranslation. In general, healthy adult tissues do not express NKG2D glycoproteins on the cell surface, but these ligands can be induced by hyperproliferation and transformation, as well as when cells are infected by pathogens. Thus, the NKG2D pathway serves as a mechanism for the immune system to detect and eliminate cells that have undergone "stress." Viruses and tumor cells have devised numerous strategies to evade detection by the NKG2D surveillance system, and diversification of the NKG2D ligand genes likely has been driven by selective pressures imposed by pathogens. NKG2D provides an attractive target for therapeutics in the treatment of infectious diseases, cancer, and autoimmune diseases.

Schilling D, Kühnel A, Tetzlaff F, et al.
NZ28-induced inhibition of HSF1, SP1 and NF-κB triggers the loss of the natural killer cell-activating ligands MICA/B on human tumor cells.
Cancer Immunol Immunother. 2015; 64(5):599-608 [PubMed] Free Access to Full Article Related Publications
The activity of natural killer (NK) cells is regulated by activating and inhibiting receptors, whereby the C-type lectin natural killer group 2D (NKG2D) receptor serves as the major activating receptor on NK cells which recognizes major histocompatibility class I chain-related proteins A and B (MICA/B). The MICA/B expression has been described to be regulated by the transcription factor heat shock factor 1 (HSF1). Inhibition of heat shock protein 90 (Hsp90) is known to induce the heat shock response via activation of HSF1 which is associated with tumor development, metastasis and therapy resistance and also with an increased susceptibility to NK cell-mediated lysis. Therefore, we compared the effects of Hsp90 inhibitor NVP-AUY922, HSF1 inhibitor NZ28 and HSF1 knockdown on the sensitivity of lung (H1339) and breast (MDA-MB-231, T47D) cancer cells to NK cell-mediated cytotoxicity and the expression of the NKG2D ligands MICA/B. Although NVP-AUY922 activates HSF1, neither the MICA/B surface density on tumor cells nor their susceptibility to NK cell-mediated lysis was affected. A single knockdown of HSF1 by shRNA decreased the surface expression of MICB but not that of MICA, and thereby, the NK cell-mediated lysis was only partially blocked. In contrast, NZ28 completely blocked the MICA/B membrane expression on tumor cells and thereby strongly inhibited the NK cell-mediated cytotoxicity. This effect might be explained by a simultaneous inhibition of the transcription factors HSF1, Sp1 and NF-κB by NZ28. These findings suggest that new anticancer therapeutics should be investigated with respect to their effects on the innate immune system.

Amin PJ, Shankar BS
Sulforaphane induces ROS mediated induction of NKG2D ligands in human cancer cell lines and enhances susceptibility to NK cell mediated lysis.
Life Sci. 2015; 126:19-27 [PubMed] Related Publications
AIMS: The goal of this study is to investigate the tumor cytotoxic effects of sulforaphane (SFN) and ionizing radiation (IR) as well as their ability to up-regulate natural killer group 2, member D (NKG2D) ligands and modulate the susceptibility of tumor cells to natural killer (NK) cell-mediated killing.
MAIN METHODS: Expression of MHC class I-related chain molecules A and B (MICA/MICB) and total reactive oxygen species (ROS) were assessed by flow cytometry following labeling with appropriate dyes or antibodies. NK cell cytotoxicity was determined by calcein release of target cells.
KEY FINDINGS: The expression of NKG2D ligands MICA/MICB was found to vary in all the four tumor cell lines tested (MCF7 < A549 < MDA-MB-231 < U937). Exposure of these cells to IR and SFN resulted in a differential induction of these ligands. IR induced an increase in expression of MICA/MICB in MCF7 cells and SFN induced MICA/MICB expression in A549 and MDA-MB-231 cells. This SFN induced increase in receptor expression resulted in increased susceptibility to NK cell mediated killing of tumor cells which was abrogated by blocking with anti-MICA/MICB antibody. SFN induced increase in MICA/MICB expression as well as increased susceptibility to NK cell mediated killing was abrogated by N-acetyl cysteine in A549 and MDA-MB-231 cells suggesting a ROS mediated mechanism.
SIGNIFICANCE: Our results indicate that SFN has an immunotherapeutic potential to be used in cancer therapy.

Lu Y, Hu J, Sun W, et al.
Hypoxia-mediated immune evasion of pancreatic carcinoma cells.
Mol Med Rep. 2015; 11(5):3666-72 [PubMed] Related Publications
Hypoxia is one of the characteristics of human and animal tumors. To investigate the association between hypoxia and the immune evasion of cancer cells, the present study examined paraffin sections of pancreatic tissues from patients with pancreatic carcinoma, chronic pancreatitis and normal pancreatic tissue and established a series of PANC‑1 cell lines, which were cultured under various hypoxic and normoxic conditions. The results demonstrated that the expression of hypoxia‑inducible 1α (HIF‑1α) in pancreatic carcinoma was significantly higher compared with that in the chronic pancreatitis and normal pancreatic tissues, which revealed that a hypoxic microenvironment existed in pancreatic carcinoma. HIF‑1α was inversely correlated with major histocompatibility complex class I chain‑related (MIC) genes, which indicated that hypoxia was involved in tumor immune evasion. The cell experiments demonstrated that the mechanism involved shedding of the MIC from the membrane of the pancreatic carcinoma cells, which then formed soluble (s)MIC. The sMIC genes downregulated natural killer (NK) group 2, member D and the cytotoxic activity of NK cells. Depending on its activity, the nitric oxide‑cyclic guanosine monophosphate‑protein kinase G signaling pathway can either increase or inhibit immune evasion of pancreatic cancer cells.

Tsukerman P, Yamin R, Seidel E, et al.
MiR-520d-5p directly targets TWIST1 and downregulates the metastamiR miR-10b.
Oncotarget. 2014; 5(23):12141-50 [PubMed] Free Access to Full Article Related Publications
MicroRNAs are key players in most biological processes. Some microRNAs are involved in the genesis of tumors and are therefore termed oncomiRs, while others, termed metastamiRs, play a significant role in the formation of cancer metastases. Previously, we identified ten different cellular microRNAs that downregulate the expression of MICB, a ligand of the activating NK receptor NKG2D. Interestingly, several of the ten MICB-targeting microRNAs, such as miR-10b, are involved in tumor formation and metastasis. In this work, we identify a complex interplay between these different microRNAs. Specifically, we demonstrate that three of the MICB-targeting microRNAs: miR-20a, miR-17-5p and miR-93, also target the same site in the 3'UTR of TWIST1, a transcription factor implicated in cancer metastasis. Additionally, we show that miR-520d-5p targets a different site in the 3'UTR of TWIST1. We next show that the miR-520d-5p-mediated decrease of TWIST1 expression results in reduced expression of one of its targets, miR-10b, and in the restoration of E-Cadherin expression, which in turn results in reduced cellular motility and invasiveness. Finally, we show that miR-520d-5p leads to reduced proliferation of tumor cells, and that high levels of miR-520d-5p correlate with higher survival rates of cancer patients.

Yang H, Lan P, Hou Z, et al.
Histone deacetylase inhibitor SAHA epigenetically regulates miR-17-92 cluster and MCM7 to upregulate MICA expression in hepatoma.
Br J Cancer. 2015; 112(1):112-21 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Epigenetic therapy using histone deacetylase inhibitors (HDACi) has shown promise in clinical trials for the treatment of human malignancies. In addition to the immediate effects on the tumour cell growth, HDACi upregulates the expression of MHC class I-related chain molecules A and B (MICA and MICB), resulting in an enhanced susceptibility of tumour cells to natural killer cell-mediated lysis. The molecular mechanism underlying is still unclear.
METHODS: The transcriptional regulation mechanism underlying suberoylanilide hydroxamic acid (SAHA)-mediated regulation of MICA and related miRNA expression was investigated using promoter acetylation assays, bioinformatics analysis and chromatin immunoprecipitation assay.
RESULTS: SAHA upregulates the transcription of MICA/B by promoting MICA-associated histone acetylation while suppressing the MICA/B-targeting miRNAs miR-20a, miR-93 and miR-106b. The mechanism by which SAHA repressed miRNAs transcription involved repression of their host genes (miR-17-92 cluster and MCM7). SAHA downregulated the miR-17-92 cluster by abolishing tyrosine phosphorylation of STAT3 and decreased MCM7 transcription through localised histone deacetylation.
CONCLUSIONS: The HDACi SAHA epigenetically upregulates MICA expression through regulating the expression of miR-17-92 cluster and MCM7 in hepatoma, thus enhancing the sensitivity of HCC to natural killer cell-mediated lysis. This novel mechanism of action provides promise for HDACi in therapy of HCC.

Ren J, Nie Y, Lv M, et al.
Estrogen upregulates MICA/B expression in human non-small cell lung cancer through the regulation of ADAM17.
Cell Mol Immunol. 2015; 12(6):768-76 [PubMed] Free Access to Full Article Related Publications
Estrogen is involved in promoting lung cancer cell division and metastasis. MICA and MICB function as ligands for NKG2D, an important immunoreceptor expressed on natural killer (NK) cells. However, whether estrogen regulates MICA/B expression and affects tumor immune escape remains unknown. In this study, we measured the mRNA levels of MICA, MICB and ADAM17in non-small cell lung cancer (NSCLC) cell lines treated with estrogen. Surface expression of MICA/B on LTEP-a2 and A549 was detected using flow cytometry. We demonstrate that both mRNA and secretory protein levels of MICA/B in lung adenocarcinoma cell lines were upregulated by estradiol. Estradiol enhanced the expression of ADAM17, which was associated with the secretion of MICA/B. This secretion of MICA/B downregulated the NKG2D receptor on the surface of NK92 cells and impaired the cytotoxic activity of NK cells. Estradiol enhanced the expression of ADAM17, which was associated with the secretion of MICA/B. Furthermore, a significant correlation between the concentration of estradiol and the expression of MICA was found in tumor tissues of NSCLC patients. Therefore, we conclude that estrogen can regulate the expression and secretion of MICA/B through ADAM17, which helps lung cancer cells escape NKG2D-mediated immune surveillance.

Fang L, Gong J, Wang Y, et al.
MICA/B expression is inhibited by unfolded protein response and associated with poor prognosis in human hepatocellular carcinoma.
J Exp Clin Cancer Res. 2014; 33:76 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: MICA/B are major ligands for NK cell activating receptor NKG2D and previous studies showed that the serum level of soluble MICA (sMICA) is an independent prognostic factor for advanced human hepatocellular carcinoma. However, the correlation between cellular MICA/B expression pattern and human hepatocellular carcinoma progression has not been well explored. The unfolded protein response is one of the main causes of resistance to chemotherapy and radiotherapy in tumor cells. However, whether the UPR in HCC could regulate the expression levels of MICA/B and affect the sensitivity of HCC cells to NK cell cytolysis has not been established yet.
METHODS: MICA/B expression pattern was evaluated by immunohistochemistry and Kaplan-Meier survival analysis was done to explore the relationship between MICA/B expression level and patient survival. The protein and mRNA expression levels of MICA/B in SMMC7721 and HepG2 cells treated by tunicamycin were evaluated by flow cytometry, Western Blot and RT-PCR. The cytotoxicity analysis was performed with the CytoTox 96 Non-Radioactive LDH Cytotoxicity Assay.
RESULTS: MICA/B was highly expressed in human hepatocellular carcinoma and the expression level was significantly and negatively associated with tumor-node metastasis (TNM) stages. Patients with low level of MICA/B expression showed a trend of shorter survival time. The unfolded protein response (UPR) downregulated the expression of MICA/B. This decreased protein expression occurred via post-transcriptional regulation and was associated with proteasomal degradation. Moreover, decreased expression level of MICA/B led to the attenuated sensitivity of human HCC to NK cell cytotoxicity.
CONCLUSION: These new findings of the connection of MICA/B, UPR and NK cells may represent a new concrete theory of NK cell regulation in HCC, and suggest that targeting this novel NK cell-associated immune evasion pathway may be meaningful in treating patients with HCC.

Jasinski-Bergner S, Mandelboim O, Seliger B
The role of microRNAs in the control of innate immune response in cancer.
J Natl Cancer Inst. 2014; 106(10) [PubMed] Related Publications
Ligands for receptors of natural killer (NK) cells and CD8(+) cytotoxic T lymphocytes (CTL), such as the inhibitory nonclassical HLA-G, the activating stress-induced major histocompatibility complex class I-related antigens MICA and MICB, and/or the UL16-binding proteins (ULBPs), are often aberrantly expressed upon viral infection and neoplastic transformation, thereby preventing virus-infected or malignant-transformed cells from elimination by immune effector cells. Recently, it has been shown that ligands of both NK and CD8(+) T cells are regulated by a number of cellular and/or viral microRNAs (miRs). These miRs are involved in shaping the antiviral and/or antitumoral immune responses as well as neoplastic growth properties. This review summarizes the expression pattern and function of miRs directed against selected NK and T cell receptor ligands, their putative role in shaping immune surveillance and tumorigenicity, and their clinical relevance. In addition, the potential role of RNA-binding proteins in the post-transcriptional gene regulation of these ligands will be discussed.

Wang B, Wang Q, Wang Z, et al.
Metastatic consequences of immune escape from NK cell cytotoxicity by human breast cancer stem cells.
Cancer Res. 2014; 74(20):5746-57 [PubMed] Related Publications
Breast cancer stem-like cells (BCSC) are crucial for metastasis but the underlying mechanisms remain elusive. Here, we report that tumor-infiltrating natural killer (NK) cells failed to limit metastasis and were not associated with improved therapeutic outcome of BCSC-rich breast cancer. Primary BCSCs were resistant to cytotoxicity mediated by autologous/allogeneic NK cells due to reduced expression of MICA and MICB, two ligands for the stimulatory NK cell receptor NKG2D. Furthermore, the downregulation of MICA/MICB in BCSCs was mediated by aberrantly expressed oncogenic miR20a, which promoted the resistance of BCSC to NK cell cytotoxicity and resultant lung metastasis. The breast cancer cell differentiation-inducing agent, all-trans retinoic acid, restored the miR20a-MICA/MICB axis and sensitized BCSC to NK cell-mediated killing, thereby reducing immune escape-associated BCSC metastasis. Together, our findings reveal a novel mechanism for immune escape of human BCSC and identify the miR20a-MICA/MICB signaling axis as a therapeutic target to limit metastatic breast cancer.

Zhao L, Wang WJ, Zhang JN, Zhang XY
5-Fluorouracil and interleukin-2 immunochemotherapy enhances immunogenicity of non-small cell lung cancer A549 cells through upregulation of NKG2D ligands.
Asian Pac J Cancer Prev. 2014; 15(9):4039-44 [PubMed] Related Publications
BACKGROUND: The aim of this study was to investigate the anti-cancer effects and mechanisms of immunochemotherapy of 5-fluorouracil (5-FU) and interleukin-2 (IL-2) on non-small cell lung cancer (NSCLC) A549 cells.
MATERIALS AND METHODS: In order to detect whether 5-FU+IL-2 could effectively inhibit tumor growth in vivo, we established an A549-bearing nude mouse model. The cytotoxicity of natural killer (NK) cells was evaluated using a standard chromium release assay. To evaluate the relevance of NK cells in 5-FU+IL-2- mediated tumor inhibitory effects, we depleted NK cells in A549-bearing mice by injecting anti-asialo-GM-1 antibodies. Effects of 5-FU+IL-2 on the expression and promoter activity of NKG2D ligands (MICA/MICB) in A549 cells in vitro were also assessed.
RESULTS: In A549-bearing nude mice, combination therapy significantly inhibited tumor growth in comparison with monotherapy with 5-FU or IL-2 and enhanced the recognition and lysis of tumor cells by NK cells. Further study of mechanisms showed that NK cells played a vital role in the anticancer immune response of 5-FU+IL-2 immunochemotherapy. In addition, the combination therapy synergistically stimulated the expression and promoter activity of MICA/MICB.
CONCLUSIONS: 5-FU and IL-2 immunochemotherapy significantly inhibited tumor growth and activated NK cytotoxicity in vivo, and these effects were partly impaired after depleting NK cells in tumor-bearing mice. Combination treatment of 5-FU and IL-2 upregulated the expression and the promoter activity of MICA/MICB in A549 cells, which enhanced the recognition of A549 cells by NK cells. All of the data indicated that immunochemotherapy of 5-FU and IL-2 may provide a new treatment option for patients with lung cancer.

Shi P, Yin T, Zhou F, et al.
Valproic acid sensitizes pancreatic cancer cells to natural killer cell-mediated lysis by upregulating MICA and MICB via the PI3K/Akt signaling pathway.
BMC Cancer. 2014; 14:370 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, is reported to exert anti-tumor effects by upregulating the expression of the natural killer group 2D (NKG2D) ligands on tumor cells; however, the mechanisms vary in different tumor types, and the effect and mechanism of action of VPA in pancreatic cancer cells are unknown.
METHODS: The present study evaluated the effect of VPA to susceptibility of pancreatic cancer cells to the NK cell-mediated lysis in vitro and in vivo. Then we investigated the mechanism which the effect of VPA depend on.
RESULTS: The lactate dehydrogenase assay (LDH) and xenograft experiment demonstrated that VPA significantly sensitized pancreatic cancer cells to NK cell-mediated lysis in vitro and in vivo. Quantitative real time- polymerase chain reaction (qRT-PCR) and flow cytometry demonstrated that VPA upregulated the mRNA and cell surface expression of the NKG2D ligands major histocompatibility complex class I-related chain A and B (MICA and MICB) in pancreatic cancer cells. Effects of VPA both in vitro and in vivo were significantly attenuated by the PI3K/Akt pathway inhibitor LY294002 or a siRNA targeting PI3K catalytic subunit alpha isoform (PI3KCA).
CONCLUSION: VPA enhances the susceptibility of pancreatic cancer cells to NK cell-mediated cytotoxicity both in vitro and in vivo by upregulating the expression of MICA and MICB via a PI3K/Akt signaling pathway-dependent mechanism.

Satwani P, Bavishi S, Saha A, et al.
Upregulation of NKG2D ligands in acute lymphoblastic leukemia and non-Hodgkin lymphoma cells by romidepsin and enhanced in vitro and in vivo natural killer cell cytotoxicity.
Cytotherapy. 2014; 16(10):1431-40 [PubMed] Related Publications
BACKGROUND AIMS: There is a critical need to prevent and/or treat hematological relapse after allogeneic hematopoietic stem cell transplantation. The activating NKG2D receptor expressed on natural killer (NK) cells, when engaged by its corresponding ligands (MIC A/B), activates NK cells to become cytotoxic against malignant cells.
METHODS: We incubated acute lymphoblastic leukemia and non-Hodgkin lymphoma cells for 24 h with 10 ng/mL of romidepsin. Flow cytometry was performed to demonstrate changes in surface expression of NKG2D ligands MIC A/B. In vitro and in vivo cytotoxicity was measured by means of modified Europium assay, and non-obese diabetic/severe combined immunodeficiency mice were xenografted with RS 4:11 cells.
RESULTS: We demonstrated an approximately 50, 200, 1300 and 180-fold increase in the number of cells positive for the surface expression of MIC A/B in RS 4:11 (P < 0.001), REH (P < 0.001), Ramos (P < 0.001) and Jurkat cells (P < 0.001), respectively. We further demonstrated a significant increase in NK cell-mediated in vitro cytotoxicity against RS 4:11 (P < 0.004), Ramos (P < 0.05), Jurkat (P < 0.001) and REH cells (P < 0.01), respectively. Romidepsin-mediated NK cytotoxicity was blocked by pre-incubating NK cells with anti-NKG2D-Fc in RS 4:11 (P < 0.03) and Ramos cells (P < 0.01), respectively. Finally, non-obese diabetic/severe combined immunodeficiency mice xenografted with RS 4:11 cells had a significant increase in survival (P < 0.02) in mice treated with romidepsin and interleukin-2-activated NK cells compared with each of these other treatment groups.
CONCLUSIONS: Romidepsin significantly enhanced in vitro and in vivo NK cell cytotoxicity mediated in part by increased MIC A/B expression on malignant cells. This translational approach of the use of romidepsin and interleukin-2-activated NK cells should be considered in patients with relapsed/refractory leukemia or lymphoma.

Xie J, Liu M, Li Y, et al.
Ovarian tumor-associated microRNA-20a decreases natural killer cell cytotoxicity by downregulating MICA/B expression.
Cell Mol Immunol. 2014; 11(5):495-502 [PubMed] Free Access to Full Article Related Publications
MicroRNAs (miRNAs) are a class of small non-coding regulatory RNAs, and changes in miRNAs are involved in tumor origin and progression. Studies have shown that miR-20a is overexpressed in human ovarian cancer tissues and that this miRNA enhances long-term cellular proliferation and invasion capabilities. In this study, a positive correlation between serum miR-20a expression and ovarian cancer stage was observed. We found that miR-20a binds directly to the 3'-untranslated region of MICA/B mRNA, resulting in its degradation and reducing its protein levels on the plasma membrane. Reduction of membrane-bound MICA/B proteins, which are ligands of the natural killer group 2 member D (NKG2D) receptor found on natural killer (NK) cells, γδ(+) T cells and CD8(+) T cells, allows tumor cells to evade immune-mediated killing. Notably, antagonizing miR-20a action enhanced the NKG2D-mediated killing of tumor cells in both in vitro and in vivo models of tumors. Taken together, our data indicate that increased levels of miR-20a in tumor cells may indirectly suppress NK cell cytotoxicity by downregulating MICA/B expression. These data provide a potential link between metastasis capability and immune escape of tumor cells from NK cells.

Fu M, Gao Y, Zhou Q, et al.
Human cytomegalovirus latent infection alters the expression of cellular and viral microRNA.
Gene. 2014; 536(2):272-8 [PubMed] Related Publications
BACKGROUND: MicroRNAs (miRNAs) play important roles in regulating gene expression of plants, animals and viruses. Comprehensive characterization of host and viral miRNA will help uncover the molecular mechanisms that underlie the progression of human cytomegalovirus (HCMV) latent infection. To investigate the miRNA expression profile of HCMV and host cells during latent infection, we performed deep-sequencing analysis of the small RNAs isolated from HCMV-infected and mock-infected human monocytic leukemia cell line, THP-1.
RESULTS: We established a HCMV latent infection cell model using the THP-1 cells. High-throughput sequencing technology was used to sequence small RNA libraries of the HCMV-infected and mock-infected THP-1 and to investigate their small RNA transcriptomes. We found eight miRNAs including miR-US25-1, miR-US25-2-5p and miR-UL112 that were expressed by HCMV during latent infection. The expressions of the host miRNAs were also affected by HCMV latent infection. At least 49 cellular miRNAs were differentially expressed: 39 were up-regulated and 10 were down-regulated upon HCMV latent infection. The expression of the human miRNA hsa-miR-124-3p was significantly up-regulated in the HCMV latent infection library. In addition, we found 14 cellular novel miRNAs in the HCMV-infected and mock-infected THP-1 libraries. Functional annotation of the target genes of the differentially expressed miRNAs suggested that the majority of the genes are involved in melanogenesis, pathways in cancer, endocytosis and wnt signaling pathway.
CONCLUSIONS: The small RNA transcriptomes obtained in this study demonstrate the usefulness of the deep-sequencing combined with bioinformatics approach in understanding of the expression and function of host and viral small RNAs in HCMV latent infection. This approach can also be applied to the study of other kinds of viruses.

Xiao W, Dong W, Zhang C, et al.
Effects of the epigenetic drug MS-275 on the release and function of exosome-related immune molecules in hepatocellular carcinoma cells.
Eur J Med Res. 2013; 18:61 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Tumor-derived exosomes have been viewed as a source of tumor antigens that can be used to induce anti-tumor immune responses. In the current study, we aim to investigate the regulatory effect of the epigenetic drug MS-275 on hepatoma G2 (HepG2) cell-derived exosomes, especially for their immunostimulatory properties and alteration of some non-specific immune protein expression, such as heat shock protein (HSP) 70, major histocompatibility complex (MHC) class I polypeptide-related sequence A (MICA) and MICB.
METHODS: MS-275 was used to modulate the secretion of exosomes in human HepG2 cells, and exosomes from untreated HepG2 cells served as negative controls. RT-PCR was used to test the expression of HSP70, MICA and MICB in HepG2 cells. Immunogold labeling of exosomes and western blotting analysis were carried out to compare the expression of HSP70, MICA and MICB proteins in exosomes with or without MS-275 treatment. A natural killer (NK) cell cytotoxicity assay and peripheral blood mononuclear cell (PBMC) proliferation assay were used to evaluate the effect of MS-275 on the immunostimulatory ability of exosomes.
RESULTS: Immunogold labeling and western blot analysis showed that modification of MS-275 increased the expression of HSP70 and MICB in exosomes. RT-PCR showed the mRNA levels of HSP70 and MICB were upregulated in HepG2 cells and were consistent with their protein levels in exosomes. The exosomes modified by MS-275 could significantly increase the cytotoxicity of NK cells and proliferation of PBMC (P < 0.05).
CONCLUSIONS: The non-specific immune response of exosomes derived from HepG2 cells could be enhanced with treatment by the histone deacetylase inhibitor (HDACi) drug MS-275; this could provide a potential tumor vaccine strategy against liver cancer.

Zhu S, Denman CJ, Cobanoglu ZS, et al.
The narrow-spectrum HDAC inhibitor entinostat enhances NKG2D expression without NK cell toxicity, leading to enhanced recognition of cancer cells.
Pharm Res. 2015; 32(3):779-92 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Natural killer (NK) cell cytotoxicity correlates with the ligation of activating receptors (e.g., NKG2D) by their ligands (e.g., MHC class I-related chains [MIC] A and B) on target cells. Histone deacetylase inhibitors (HDACi) at high concentrations inhibit tumor growth and can increase NKG2D ligand expression on tumor targets, but are widely regarded as toxic to NK cells.
METHODS: We investigated the mechanism of entinostat, a benzamide-derivative narrow-spectrum HDACi, in augmenting the cytotoxicity of NK cells against human colon carcinoma and sarcoma by assessing gene and protein expression, histone acetylation, and cytotoxicity in in vitro and murine models.
RESULTS: We observed that entinostat dose- and time-dependent increase in MIC expression in tumor targets and NKG2D in primary human NK cells, both correlating with increased acetylated histone 3 (AcH3) binding to associated promoters. Entinostat pretreatment of colon carcinoma and sarcoma cells, NK cells, or both led to enhanced overall cytotoxicity in vitro, which was reversed by NKG2D blockade, and inhibited growth of tumor xenografts. Lastly, we showed decreased expression of MICA and ULBP2 transcription in primary human osteosarcoma.
CONCLUSIONS: Entinostat enhances NK cell killing of cancer cells through upregulation of both NKG2D and its ligands, suggesting an attractive approach for augmenting NK cell immunotherapy of solid tumors such as colon carcinoma and sarcomas.

Leung WH, Vong QP, Lin W, et al.
Modulation of NKG2D ligand expression and metastasis in tumors by spironolactone via RXRγ activation.
J Exp Med. 2013; 210(12):2675-92 [PubMed] Free Access to Full Article Related Publications
Tumor metastasis and lack of NKG2D ligand (NKG2DL) expression are associated with poor prognosis in patients with colon cancer. Here, we found that spironolactone (SPIR), an FDA-approved diuretic drug with a long-term safety profile, can up-regulate NKG2DL expression in multiple colon cancer cell lines by activating the ATM-Chk2-mediated checkpoint pathway, which in turn enhances tumor elimination by natural killer cells. SPIR can also up-regulate the expression of metastasis-suppressor genes TIMP2 and TIMP3, thereby reducing tumor cell invasiveness. Although SPIR is an aldosterone antagonist, its antitumor effects are independent of the mineralocorticoid receptor pathway. By screening the human nuclear hormone receptor siRNA library, we identified retinoid X receptor γ (RXRγ) instead as being indispensable for the antitumor functions of SPIR. Collectively, our results strongly support the use of SPIR or other RXRγ agonists with minimal side effects for colon cancer prevention and therapy.

Dambrauskas Z, Svensson H, Joshi M, et al.
Expression of major histocompatibility complex class I-related chain A/B (MICA/B) in pancreatic carcinoma.
Int J Oncol. 2014; 44(1):99-104 [PubMed] Related Publications
Major histocompatibility complex class I-related chain A and B (MICA/B) are two stress-inducible ligands that bind to the immunoreceptor NKG2D and play an important role in mediating cytotoxicity of NK and T cells. Release of MIC molecules from the cell surface is thought to constitute an immune escape mechanism of tumor cells and thus could be associated with more aggressive course of tumor growth. In this study, we investigated the expression of MICA/B in ductal pancreatic carcinoma and serum in relation to tumor stage, differentiation and survival. MICA/B expression in tumor tissues and sera from patients with pancreatic cancer were analyzed by immunohistochemical staining (IHC), western blotting and ELISA, respectively. MICA/B expression was present in 17 of 22 (77%) of the tumors but not in normal pancreatic ductal epithelial cells. Poorly differentiated tumors showed more pronounced MICA/B expression compared to differentiated tumors, but did not correlate significantly to other tumor characteristics. MICA/B-negative tumors displayed significantly lower incidence of lymph node metastases (p<0.01), and less mortality within 3 years following resection (p<0.02). In conclusion, tissue levels of MICA/B expression were elevated in pancreatic cancer cells without elevated levels in serum, despite well-recognized acute phase reactants in serum. Poorly differentiated tumors showed high MICA/B expression, which was related to extended tumor lymph node metastases and less frequent long-term survival.

Gadji M, Crous-Tsanaclis AM, Mathieu D, et al.
A new der(1;7)(q10;p10) leading to a singular 1p loss in a case of glioblastoma with oligodendroglioma component.
Neuropathology. 2014; 34(2):170-8 [PubMed] Related Publications
The combined 1p-/19q- deletions in oligodendrogliomas originate from translocation between both chromosomes. In the few cases of oligoastrocytomas and glioblastomas with an oligodendroglioma component (GBMO) where only 1p deletion was described, the origin remains unknown. We report the first case of GBMO, in which a single 1p deletion was detected and was linked to a translocation between chromosomes 1 and 7. Fresh surgical specimens were collected during surgery and the samples were used for cell culture, touch preparation smear slides (TP slides) and DNA extraction. Peripheral venous blood was also collected from the patient. G-banding using Trypsin and stained with Giemsa (GTG) banding and karyotyping were performed and 1p-/19q-, TP53, PTEN and c-MYC were analyzed by fluorescent in situ hybridization (FISH). Multicolor FISH (mFISH) and microsatellites analyses were also performed to complete the investigation. Three-dimensional quantitative FISH (3D-QFISH) of telomeres was performed on nuclei from TP slides and analyzed using TeloView(TM) to determine whether the 3D telomere profile as an assessment of telomere dysfunction and a characterization of genomic instability could predict the disease aggressiveness. An unbalanced chromosomal translocation was found in all metaphases and confirmed by mFISH. The karyotype of the case is: 50∼99,XXX, +der(1;7)(q10;p10),inc[47] The derivative chromosome was found in all 47 analyzed cells, but the number of derivatives varied from one to four. There was neither imbalance in copy number for genes TP53 and PTEN, nor amplification of c-MYC gene. We did not find loss of heterozygosity with analysis of microsatellite markers for chromosomes 1p and 19q in tumor cells. The 3D-telomere profile predicted a very poor prognostic and short-term survival of the patient and highlights the potential clinical power of telomere signatures as a solid biomarker of GBMO. Furthermore, this translocation between chromosomes 1 and 7 led to a singular 1p deletion in this GBMO and may generate the 1p and 7q deletions.

Wu J, Zhang XJ, Shi KQ, et al.
Hepatitis B surface antigen inhibits MICA and MICB expression via induction of cellular miRNAs in hepatocellular carcinoma cells.
Carcinogenesis. 2014; 35(1):155-63 [PubMed] Related Publications
Hepatitis B surface antigen (HBsAg) seropositivity is an important risk factor for hepatocellular carcinoma (HCC), and HBsAg-transgenic mice have been reported to spontaneously develop HCC. The major histocompatibility complex class I-related molecules A and B (MICA and MICB) are NKG2D ligands that play important roles in tumor immune surveillance. In the present study, we found that HBsAg overexpression in HepG2 cells led to upregulation of 133 and downregulation of 9 microRNAs (miRNAs). Interestingly, several HBsAg-induced miRNAs repressed the expression of MICA and MICB via targeting their 3'-untranslated regions. In addition, the expression of MICA and MICB was significantly reduced upon HBsAg overexpression, which was partially restored by inhibiting the activities of HBsAg-induced miRNAs. Moreover, HBsAg-overexpressing HCC cells exhibited reduced sensitivity to natural killer cell-mediated cytolysis. Taken together, our data suggest that HBsAg supresses the expression of MICA and MICB via induction of cellular miRNAs, thereby preventing NKG2D-mediated elimination of HCC cells.

Sauer M, Reiners KS, Hansen HP, et al.
Induction of the DNA damage response by IAP inhibition triggers natural immunity via upregulation of NKG2D ligands in Hodgkin lymphoma in vitro.
Biol Chem. 2013; 394(10):1325-31 [PubMed] Related Publications
Evasion of apoptosis is a hallmark of cancer cells. Inhibitor of apoptosis proteins (IAPs) act as endogenous inhibitors of programmed cell death and are overexpressed in several tumors including Hodgkin lymphoma (HL). Preclinical studies indicate antitumor activity of IAP antagonists and clinical studies in hematological malignancies are underway. Here, we investigate the impact of the small molecule IAP antagonist LCL161 on HL cell lines. Although the antagonist caused rapid degradation of cIAP1 leading to TNFα secretion, LCL161 did not promote apoptosis significantly. However, LCL161 induced expression of MICA and MICB, ligands for the activating immune receptor NKG2D, and enhanced the susceptibility of HL cells to NKG2D-dependent lysis by NK cells. MICA/B upregulation was dependent on activation of the DNA damage response upon LCL161 treatment. Taken together, we demonstrate a novel link between IAP inhibition, DNA damage and immune recognition.

Jung TY, Choi YD, Kim YH, et al.
Immunological characterization of glioblastoma cells for immunotherapy.
Anticancer Res. 2013; 33(6):2525-33 [PubMed] Related Publications
The aim of this study was the immunological characterization of glioblastoma cells. Glioblastoma cell lines were cultured in serum and serum-free neurobasal (NBE) medium conditions. These cell lines were characterized by flow cytometry, reverse transcription-polymerase chain reaction (RT-PCR), western blot and natural killer (NK) cell-cytotoxicity assays. A previously described NK cell expansion method that uses K562 cells expressing interleukin (IL)-15 and 4-1 BB Ligand (BBL) (K562-mb15-41BBL) was used. RT-PCR and western blots for the expression of tumor-associated antigens (TAAs), were carried out in 32 glioblastoma and seven normal brain tissues. U87 and U343 tumor cell lines showed increased expression for major histocompatibility complex (MHC)-I and -II molecules. No significant differences in the levels of CD133, MHC class I/II, MHC class I-related chain A (MICA), MICB, UL16 binding protein 1-3 (ULBP 1-3) expression in these cell lines and in NK cell cytotoxicity were observed between serum and NBE conditions. Regardless of culture conditions, U87 and U343 cell lines were sensitive to expanded NK cells, with median cytotoxicities at 4:1 effector/target ratio of 43.2% and 46.5%, respectively. In RT-PCR, U343 and U87 showed the expression of most TAAs at a high ratio compared with U251. Western blots demonstrated positive expression for BIRC5, CD99 and ERBB2 in U251, U87 and U343 cell lines and tissues. These highly-expressed TAAs such as BIRC5, CD99 and ERBB2 in glioblastoma tissue could be the targets for immunotherapy. U87 and U343 cell lines could be useful for studying the efficacy of immunotherapy related to various TAAs and NK cell immunotherapy.

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