Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mouse HER2-derived peptide, HER2p63 (A) (TYLPANASL), can induce K(d)-restricted mouse cytotoxic T lymphocytes (CTL) and also function as a tumor rejection antigen in an in vivo assay. Since the anchor motif of mouse K(d) for peptide binding has much similarity to that of human HLA-A2402, we asked if human HER2p63 (T) (TYLPTNASL) could induce HER2-specific CTL in HLA-A2402-positive individuals. Peripheral blood mononuclear cells (PBMC) of HLA-A2402-positive individuals were sensitized in vitro with HER2p63-pulsed autologous dendritic cells prepared from PBMC. CTL clone derived from these specifically lysed HER2-expressing cell lines bearing HLA-A2402. Cytotoxic activity of the CTL clone against the HER2-expressing cell line bearing HLA-A2402 was blocked by antibodies against CD3, CD8, HLA-A24 or MHC class I, and was also inhibited by the addition of excess HER2p63-pulsed C1R bearing HLA-A2402. Killer cells were generated from PBMC of seven healthy individuals and five ovarian cancer patients, all of HLA-A2402 type, by in vitro sensitization with HER2p63-pulsed autologous antigen presenting cells. These killer cells selectively lysed HER2-expressing SKOV3 transfected with HLA-A2402 cDNA, indicating high immunogenicity of HER2p63 in all 12 individuals examined.
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PMID:A novel human HER2-derived peptide homologous to the mouse K(d)-restricted tumor rejection antigen can induce HLA-A24-restricted cytotoxic T lymphocytes in ovarian cancer patients and healthy individuals. 1109 50

It has been proposed that adoptive immunotherapy, for the treatment of relapsed AML, with cytotoxic T lymphocytes which show a relative specificity for the leukemic cells may have the advantage of maximizing the beneficial anti-leukemic effect whilst minimizing the probability of graft-versus-host disease. In this study we differentiated peripheral blood AML cells in vitro into functional dendritic cells (DCs), as demonstrated by cell morphology, immunophenotype and functional activity, in the presence of GM-CSF, IL-4, TNF-alpha and FLT3 ligand. Such DCs could be differentiated from 77% of AML patients, irrespective of their FAB classification and clinical status and, in all cases tested, the DCs were shown to derive from the leukemic clone by FISH analysis. Importantly, from >60% of AML patients, autologous T lymphocytes stimulated with these in vitro generated leukemic DCs displayed specific cytotoxic activity against AML blasts but low reactivity against autologous non-leukemic targets and HLA-matched normal PBMNCs therefore suggesting that the CTLs were AML-specific. The use of FLT3 ligand in our system resulted in a significantly higher number of leukemic DCs as compared to cultures from which FLT3 ligand was omitted which is obviously advantageous if large numbers of specific CTLs are to be generated in the shortest possible time.
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PMID:Leukemic dendritic cells generated in the presence of FLT3 ligand have the capacity to stimulate an autologous leukemia-specific cytotoxic T cell response from patients with acute myeloid leukemia. 1123 40

Tumor specific CTLs are susceptible to tumor-mediated activated induced cell death (AICD) after target engagement. The presence of dendritic cells (DCs) at the site of tumors correlates with an improved prognosis in patients with a variety of histological tumor types. We examined whether DCs can modify the survival of tumor specific CTLs during encounter with tumor targets. HLA-A2+ gp100-specific CD8+ CTLs were used as effectors against gp100+, A2+ melanoma FEM-X, and Mel526 (A2-) targets as well as the melanoma target Mel397. Cytolytic assays and [3H]DNA fragmentation (JAM) assays were used to evaluate CTL specificity and tumor-mediated AICD, respectively. A functional assay, ARK (activity of rescued killer cells), was developed to measure cytolytic activity of surviving CTLs after a 12-h coincubation with tumor. In JAM assays, the CTLs proved more susceptible to apoptosis when exposed to the relevant tumors FEM-X and Mel526 than the irrelevant Mel397 (37 and 23% versus 3%; P < .001). The addition of human A2+ monocyte-derived immature DCs significantly (P < 0.001) limited this tumor-induced death of CTLs. In ARK assays, the presence of DCs decreased tumor-mediated suppression of CTLs, with increases in cytolytic function of CTLs reaching up to 2-fold. These findings suggest that DCs may play an important role during the effector phase of the immune response by enhancing the survival and function of CTLs in the tumor microenvironment.
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PMID:Dendritic cells prolong tumor-specific T-cell survival and effector function after interaction with tumor targets. 1130 May

Malignant cells may escape from the immune response in vivo because of a defective differentiation of professional antigen-presenting cells (APCs), i.e., dendritic cells (DCs). We recently reported that tumor cells release interleukin (IL)-6 and macrophage colony stimulating factor (M-CSF), which inhibit the differentiation of CD34+ cells into DCs and promote their commitment toward monocytic lineage with a poor APC function. The results presented here show that both IL-4 and IL-13 reverse the inhibitory effects of renal cell carcinoma conditioned media (RCC CM) or IL-6+M-CSF on the phenotypic and functional differentiation of CD34+ into DCs. IL-4 was found to act through a rapid blockade of the expression of M-CSF and the IL-6 receptor-transducing chain (gp130), along with a decrease of the secondary production of M-CSF, thereby preventing the loss of granulocyte macrophage colony stimulating factor (GM-CSF) receptor alpha chain expression on differentiating CD34+ cells. Consistent with these observations, the differentiation of DCs from monocytes cultured with GM-CSF and IL-4 was also impaired by RCC CM, but the minimal inhibitory concentrations of RCC CM were 10-fold higher than for CD34+ cells. In these conditions, monocytes cultured with GM-CSF and IL-4 also exhibited profound phenotypic changes (CD14+ D32+ CD86+ HLA-DR+ CD115(low) CD23(low) CD1a-) and a poor APC function. These alterations were overcome in a dose-dependent manner by IL-4 (5-500 IU/ml), although not beyond a 40% final concentration of RCC CM. The capacity of RCC CM to block DC differentiation from monocytes strongly correlated with IL-6 and M-CSF concentrations in medium. Taken together, these results demonstrate that IL-4 and IL-13 reverse the inhibitory effect of tumor cells on DC differentiation.
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PMID:IL-4 prevents the blockade of dendritic cell differentiation induced by tumor cells. 1130 93

Tolerance in vivo and its in vitro counterpart, anergy, are defined as the state in which helper T lymphocytes are alive but incapable of producing IL-2 and expanding in response to optimal antigenic stimulation. Anergy is induced when the T cell receptor (TCR) is engaged by antigen in the absence of costimulation or IL-2. This leads to unique intracellular signaling events that stand in contrast to those triggered by coligation of the TCR and costimulatory receptors. Specifically, anergy is characterized by lack of activation of lck, ZAP 70, Ras, ERK, JNK, AP-1, and NF-AT. In contrast, anergizing stimuli appear to activate the protein tyrosine kinase fyn, increase intracellular calcium levels, and activate Rap1. Moreover, anergizing TCR signals result in increased intracellular concentrations of the second messenger cAMP. This second messenger upregulates the cyclin-dependent kinase (cdk) inhibitor p27kip1, sequestering cyclin D2-cdk4, and cyclin E/cdk2 complexes and preventing progression of T cells through the G1 restriction point of the cell cycle. In contrast, costimulation through CD28 prevents p27kip1 accumulation by decreasing the levels of intracellular cAMP and promotes p27kip1 down-regulation due to direct degradation of the protein via the ubiquitin-proteasome pathway. Subsequent autocrine action of IL-2 leads to further degradation of p27kip1 and entry into S phase. Understanding the biochemical and molecular basis of T cell anergy will allow the development of new assays to evaluate the immune status of patients in a variety of clinical settings in which tolerance has an important role, including cancer, autoimmune diseases, and organ transplantation. Precise understanding of these biochemical and molecular events is necessary in order to develop novel treatment strategies against cancer. One of the mechanisms by which tumors down-regulate the immune system is through the anergizing inactivation of helper T lymphocytes, resulting in the absence of T cell help to tumor-specific CTLs. Although T-cells specific for tumor associated antigens are detected in cancer patients they often are unresponsive. Reversal of the defects that block the cell cycle progression is mandatory for clonal expansion of tumor specific T cells during the administration of tumor vaccines. Reversal of the anergic state of tumor specific T cells is also critical for the sufficient expansion of such T cells ex vivo for adoptive immunotherapy. On the other hand, understanding the molecular mechanisms of anergy will greatly improve our ability to design novel clinical therapeutic approaches to induce antigen-specific tolerance and prevent graft rejection and graft-versus-host disease. Such treatment approaches will allow transplantation of bone marrow and solid organs between individuals with increasing HLA disparity and therefore expand the donor pool, enable reduction in the need for nonspecific immunosuppression, minimize the toxicity of chemotherapy, and reduce the risk of opportunistic infections.
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PMID:Helper T cell anergy: from biochemistry to cancer pathophysiology and therapeutics. 1143 20

HER2/neu-derived peptides inducing MHC class II-restricted CD4+ T helper lymphocyte (Th) responses, although critical for tumour rejection, are not thoroughly characterized. Here, we report the generation and characterization of CD4+ T cell clones specifically recognizing a HER-2/neu-derived peptide (776-788) [designated HER2(776-788)]. Such clones yielded specific proliferative and cytokine [gamma-interferon(IFN)-gamma] responses when challenged with autologous dendritic cells (DCs) loaded with HER2(776-788). By performing blocking studies with monoclonal antibodies (MAbs) and by using DCs from allogeneic donors sharing certain HLA-DR alleles, we found that HER2(776-788) is a promiscuous peptide presented, at least, by DRB5*0101, DRB1*0701 and DRB1*0405 alleles. One TCRV beta 6.7+ clone recognized the HLA-DRB5*0101+ FM3 melanoma cell line transfected with a full length HER-2/neu cDNA. Moreover, this clone recognized the HER-2/neu+ SKBR3 breast cancer cell line induced to express HLA-DR, thus demonstrating that HER2(776-788) represents a naturally processed and presented epitope. Our data demonstrate that helper peptide HER2(776-788) represents a promiscuous epitope binding to at least three HLA-DR alleles, thus offering a broad population coverage. The use of antigenic peptides presented by major histocompatibility complex (MHC) class II in addition to those presented by class I may improve the therapeutic efficacy of active immunization.
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PMID:Peptide HER2(776-788) represents a naturally processed broad MHC class II-restricted T cell epitope. 1172 Apr 40

HER-2/neu is a tumor-associated antigen overexpressed in a large variety of human tumors. Eight HER-2/neu peptides displaying HLA-A*0201 anchoring motifs were selected and tested for their binding affinity to HLA-A*0201 and their capacity to elicit cytotoxic T lymphocyte (CTL) responses in both HLA-A*0201 transgenic mice and in HLA-A*0201(+) healthy donors. Two high-affinity (p5 and p48) and one intermediate-affinity (p1023) peptides triggered CTL responses in both transgenic mice and humans, comparable to those observed for the well-known HER2/neu dominant peptide p369. CTL induced in transgenic mice lysed HLA-A*0201(+) RMA cells infected with recombinant HER-2/neu but not cells infected with wild-type vaccinia virus. Human CTL lysed HLA-A*0201(+) HER-2/neu(+) tumor cells of different origins (breast, colon, lung and renal cancer) irrespective of the expression levels of HER-2/neu. Importantly, primed CTL specific for these epitopes were detected in freshly isolated tumor-infiltrating lymphocytes from three renal cell carcinoma patients. Therefore, the HER-2/neu peptides p5, p48 and p1023 may be good candidates for immunotherapy of a broad spectrum of tumors, including renal cell carcinoma.
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PMID:Identification of HER-2/neu immunogenic epitopes presented by renal cell carcinoma and other human epithelial tumors. 1174 43

Oncogenic anaplastic lymphoma kinase (ALK) fusion proteins (NPM/ALK and associated variants) are expressed in about 60% of anaplastic large cell lymphomas (ALCLs) but are absent in normal tissues. In this study, we investigated whether ALK, which is expressed at high levels in lymphoma cells, could be a target for antigen-specific cell-mediated immunotherapy. A panel of ALK-derived peptides was tested for their binding affinity to HLA-A*0201 molecules. Binding peptides were assessed for their capacity to elicit a specific immune response mediated by cytotoxic T lymphocytes (CTLs) both in vivo, in HLA-A*0201 transgenic mice, and in vitro in the peripheral blood lymphocytes (PBLs) from healthy donors. Two HLA-A*0201-restricted CTL epitopes, p280-89 (SLAMLDLLHV) and p375-86 (GVLLWEIFSL), both located in the ALK kinase domain were identified. The p280-89- and p375-86-induced peptide-specific CTL lines were able to specifically release interferon-gamma (IFN-gamma) on stimulation with ALK peptide-pulsed autologous Epstein-Barr virus-transformed B cells (LCLs) or T2 cells. Anti-ALK CTLs lysed HLA-matched ALCL and neuroblastoma cell lines endogenously expressing ALK proteins. CTL activity was inhibited by anti-HLA-A2 monoclonal antibody CR11.351, consistent with a class I-restricted mechanism of cytotoxicity. These results show the existence of functional anti-ALK CTL precursors within the peripheral T-cell repertoire of healthy donors, clearly indicating ALK as a tumor antigen and ALK-derived peptides, p280-89 and p375-86, as suitable epitopes for the development of vaccination strategies.
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PMID:ALK as a novel lymphoma-associated tumor antigen: identification of 2 HLA-A2.1-restricted CD8+ T-cell epitopes. 1187 85

Recognition of the essential role of dendritic cells (DCs) as professional antigen-presenting cells has prompted investigators to search for methods to use DCs as natural adjuvants in immunotherapy. A number of antigenic oligopeptides, recognized by CD8(+) cytotoxic T lymphocytes (CTLs) specific for cancer cells, have been applied in clinical trials using DCs. Such a monovalent vaccine with a single epitope for a particular type of HLA class 1 molecule would be effective. However, a polyvalent vaccine might be more potent. We designed a novel protein delivery system consisting of hydrophobized polysaccharides complexed with target proteins. The truncated HER2 protein encompassing 147 N-terminal amino acids, including the 9-mer HER2p63-71 peptide (HER2p63), TYLPTNASL, the human homologue of an antigenic murine tumor rejection peptide, was prepared. We report here that HLA-A2402(+) DCs could incorporate hydrophobized polysaccharide-truncated HER2 protein complexes and process the protein to present major histocompatibility complex class 1-binding HER2p63 peptide. The complexes enter DCs by phagocytosis, and then the truncated protein is processed through a pathway similar to that for endogenous proteins. DCs sensitized by these complexes primed and boosted HER2p63-specific CD8(+) T cells in the context of HLA-A2402. Vaccination with DCs incorporating these complexes completely suppressed lung metastases in a HER2-expressing murine tumor model. We also generated 3 CD4(+) clones reactive with different HER2- derived 25-mer peptides from lymph node cells in mice treated with CHP/HER2-147. Thus, hydrophobized polysaccharide-protein complexes are promising candidates for the construction of polyvalent vaccines.
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PMID:Presentation of a major histocompatibility complex class 1-binding peptide by monocyte-derived dendritic cells incorporating hydrophobized polysaccharide-truncated HER2 protein complex: implications for a polyvalent immuno-cell therapy. 1198 28

HA(306-318) is an immunodominant peptide of the hemagglutinin of influenza virus that binds to most human leukocyte antigen (HLA-DR) alleles, while p18(73-85) is a HIV peptide characterized as a DR101 binding peptide. Our results demonstrate that crystal relaxation leads to the loss of a hydrogen bond between the beta81 histidine and the HA(306-318) peptide. This histidine is also involved in the binding of superantigens like SEA via a coordination of a zinc atom. To monitor the interaction of these peptides with this histidine of HLA-DR molecules, chemical modification, peptide binding on HLA-DR101 wild type and mutated molecules, and proliferation experiments were conducted, together with molecular simulation of HLA-DR/peptide molecular complexes. Our data suggest a different binding peptide pattern, depending of whether the peptide is HLA-DR101 allele specific or a shared one. Furthermore, tyrosine substitution at position beta81 does not affect either peptide binding or HA(306-318) clone-specific T-cell proliferation. On the contrary, the alanine substitution at position HLA-DR101 beta81 abrogated both peptide binding and T-cell proliferation. These results suggest that the histidine 81 on the DRbeta chain plays an important role in the HLA-DR peptide binding, more likely by polar interactions of the amino acid side chain ring with the peptide.
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PMID:Influence of histidine beta81 of HLA-DR101 on peptide binding and presentation to T-cell receptor. 1203 21


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