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)

We tested the hypothesis that bispecific Abs (Bsab) with increased binding affinity for tumor Ags augment retargeted antitumor cytotoxicity. We report that an increase in the affinity of Bsab for the HER2/neu Ag correlates with an increase in the ability of the Bsab to promote retargeted cytotoxicity against HER2/neu-positive cell lines. A series of anti-HER2/neu extracellular domain-directed single-chain Fv fragments (scFv), ranging in affinity for HER2/neu from 10(-7) to 10(-11) M, were fused to the phage display-derived NM3E2 human scFV: NM3E2 associates with the extracellular domain of human FcgammaRIII (CD16). The resulting series of Bsab promoted cytotoxicity of SKOV3 human ovarian carcinoma cells overexpressing HER2/neu by human PBMC preparations containing CD16-positive NK cells. The affinity for HER2/neu clearly influenced the ability of the Bsab to promote cytotoxicity of (51)Cr-labeled SKOV3 cells. Lysis was 6.5% with an anti-HER2/neu K(D) = 1.7 x 10(-7) M, 14.5% with K(D) = 5.7 x 10(-9) M, and 21.3% with K(D) = 1.7 x 10(-10) M at 50:1 E:T ratios. These scFv-based Bsab did not cross-link receptors and induce leukocyte calcium mobilization in the absence of tumor cell engagement. Thus, these novel Bsab structures should not induce the dose-limiting cytokine release syndromes that have been observed in clinical trials with intact IgG BSAB: Additional manipulations in Bsab structure that improve selective tumor retention or facilitate the ability of Bsab to selectively cross-link tumor and effector cells at tumor sites should further improve the utility of this therapeutic strategy.
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PMID:Increasing the affinity for tumor antigen enhances bispecific antibody cytotoxicity. 1134 30

The activation of protein tyrosine kinase(s) (PTK) is a critical event required for the development of NK cell-mediated cytotoxicity. Here we demonstrate that the adaptor protein shc undergoes tyrosine phosphorylation during the generation of antibody-dependent cellular cytotoxicity (ADCC) and natural killing. In addition, we report that, upon direct or antibody-dependent target cell interaction, shc coprecipitates with the Src homology 2 (SH2)-containing inositol phosphatase, SHIP. To gain information on the functional role of shc in NK cytotoxicity, we overexpressed wild-type or dominant negative shc constructs in the human NKL cell line. Our findings show a consistent shc-mediated down-regulation of ADCC and natural killing. Such functional effect correlates with a perturbation of the phosphoinositide (PI) metabolism by means of a shc-mediated negative regulation of inositol 1,4,5 triphosphate (IP3) generation and intracellular calcium flux upon CD16 ligation. Furthermore, our data show that dominant-negative shc-mediated perturbation of shc/SHIP interaction leads to inhibition of ligand-dependent SHIP recruitment to CD16 zeta chain. We suggest that shc plays a role of negative adaptor by modulating SHIP recruitment to activation receptors involved in the generation of NK cytotoxic function.
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PMID:The adaptor protein shc is involved in the negative regulation of NK cell-mediated cytotoxicity. 1144 54

Clinical use of Herceptin (trastuzumab), which is a humanized monoclonal antibody against HER2, started for patients with HER2-overexpressing breast cancer. To potentiate the efficacy of the Herceptin therapy, this study focused on the combination of Herceptin with activated immune lymphocytes. We used peripheral blood mononuclear cells (PBMCs) as effector cells and used HER2-unexpressing K562 cells, HER2-weakly-expressing breast carcinoma cells (Breast-M), or HER2-strongly-expressing breast carcinoma cells (BT-474) as target cells. Interleukin-2 (IL-2)-activated PBMCs, IL-2/OKT-3-activated PBMCs and a streptococcal preparation OK-432-activated PBMCs were generated and used as effector cells. Cytotoxic activity was determined with 4-hour 51Cr release assay. Both fresh PBMCs and activated PBMCs exhibited Herceptin-dependent cytotoxicity. Importantly, Herceptin-dependent cytotoxicity was found even at a lower effector to target cell ratio (E/T ratio) than that of Herceptin-independent cytotoxicity. In addition, Herceptin-dependent cytotoxicity by these activated PBMCs was observed even in HER2-weakly-expressing Breast-M cells. Since gamma-globulin or anti-CD16 antibody abrogated Herceptin-dependent cytotoxicity, it seems likely that antibody-dependent cellular cytotoxicity (ADCC) plays an important role in the Herceptin-dependent cytotoxicity. We present a recurrent breast cancer patient with malignant pleural effusion, in which HER2-strongly-expressing tumor cells were present, who was undergoing Herceptin therapy. Cluster formation between tumor cells and intrapleural mononuclear cells was induced 24 hours after intravenous injection of Herceptin (4 mg/kg). Mononuclear cells bound specifically to HER2-strongly-expressing tumor cells but not to other cells, such as mesothelial cells, suggested a Herceptin-mediated binding like ADCC in vivo. Taken together, these findings suggest that the combination of Herceptin with various types of activated lymphocytes may be a new therapeutic strategy, not only for HER2-strongly-expressing breast cancer but also for HER2-weakly-expressing cancer.
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PMID:Combination of adoptive immunotherapy with Herceptin for patients with HER2-expressing breast cancer. 1466 32

Unconjugated monoclonal antibodies have emerged as important therapeutic agents for selected malignancies. One mechanism by which antibodies can exert cytotoxic effects is antibody-dependent cellular cytotoxicity (ADCC). In an effort to increase the efficiency of ADCC at tumor sites, we have focused on the construction of bispecific antibodies specific for the tumor antigen HER2/neu and the Fc gamma RIII-activating receptor (CD16) found on NK cells, mononuclear phagocytes, and neutrophils. Here, we describe the production of bispecific minibodies in two distinct binding formats. The parent minibody was constructed such that the IgG1 C(H)3 constant domain serves as the oligomerization domain and is attached to an anti-CD16 and an anti-HER2/ neu single-chain Fv via 19- and 29-amino acid linkers, respectively. This molecule can be expressed in mammalian cells from a dicistronic vector and has been purified using sequential affinity purification techniques. Analysis by surface plasmon resonance shows that the bispecific minibody can bind to HER2/neu and CD16, both individually and simultaneously. Furthermore, cytotoxicity studies show that the minibody can induce significant tumor cell lysis at a concentration as low as 20 nm. A trimeric, bispecific minibody (TriBi) that binds dimerically to HER2/neu and monomerically to CD16 induces equivalent cytotoxicity at lower antibody concentrations than either the parent minibody or the corresponding single-chain dimer. Both minibody constructs are stable in mouse and human serum for up to 72 h at 37 degrees C. These minibodies have the potential to target solid tumors and promote tumor lysis by natural killer cells and mononuclear phagocytes.
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PMID:Bispecific minibodies targeting HER2/neu and CD16 exhibit improved tumor lysis when placed in a divalent tumor antigen binding format. 1547 59

We investigated whether trastuzumab, a humanized anti-HER2 monoclonal antibody, could induce HER2-specific cytotoxic activity on lymphokine-activated killer (LAK) cells. Trastuzumab alone was not toxic to the HER2-positive breast cancer cell lines MDA-MB453 and ZR75-1, nor to the HER2-negative breast cancer cell lines MDA-MB468 and MCF-7. LAK cells, which were activated with 1000 U/ml IL-2 for 4 days (4-day LAK), showed cytotoxic activity against the MDA-MB453, ZR75-1 and MCF-7 cells, but not against MDA-MB468 cells. LAK cell cytotoxic activity against the HER2-positive breast cancer cell lines MDA-MB453 and ZR75-1 was significantly augmented in the presence of 10 nM trastuzumab, but that against the HER2-negative breast cancer cell lines MDA-MB468 and MCF-7 was not. The cytotoxic activity of LAK cells plus trastuzumab against the MDA-MB453 cells was significantly inhibited by the addition of cold MDA-MB453 cells or cold ZR75-1 cells, but not by addition of cold MDA-MB468 cells. Twenty-nine percent of the 4-day LAK cells were CD16+, and the cytotoxicity of LAK cells plus trastuzumab was abrogated with the anti-CD16 antibody treatment of the LAK cells in the cytotoxicity assay. Only 7% of the 10-day LAK cells were CD16+, and the 10-day LAK cells failed to exhibit cytotoxicity even with trastuzumab. These results suggest that HER2-specific cytotoxic activity, which is mediated by an antibody-dependent cellular cytotoxicity (ADCC) mechanism, can be induced on LAK cells by the addition of trastuzumab.
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PMID:HER2-specific cytotoxic activity of lymphokine-activated killer cells in the presence of trastuzumab. 1586 15

Methods that allow expansion of myeloid dendritic cells (MDCs) from CD34(+) cells are potentially important for boosting anti-leukemic responses after cord blood (CB) hematopoietic stem cell transplantation (HSCT). We showed that the combination of early-acting cytokines FLT3-ligand (FL), stem cell factor (SCF), interleukin (IL)-3, and IL-6 supported the generation of CD11c(+)CD16() CD1a()/c() MDCs from CB CD34(+) cells or CB myeloid precursors. Early-acting cytokine-derived MDCs were maintained within the myeloid CD33(+)CD14()CD15() precursors with a mean of 4 x 10(6) cells generated from 1-4 x 10(4) CB CD34(+) cells or myeloid precursors after 2 weeks. After 8-12 days of culture the MDCs expressed higher levels of HLA-DR antigen but lower levels of CD40 and CD86 antigen, compared to adult blood MDCs. At this stage of differentiation, the early-acting cytokine-derived MDCs had acquired the ability to induce greater allogeneic T cell proliferation than monocytes or granulocytes derived from same culture. Early-acting cytokine-derived MDCs exposed to the cytokine cocktail (CC) comprising IL-1beta, IL-6, tumor necrosis factor (TNF)-alpha, and prostaglandin E (PGE)-2, upregulated the surface co-stimulatory molecules CD40 and CD86 and enhanced allogeneic T cell proliferation, as is characteristic of MDCs maturation. The reliable production of MDCs from CB CD34(+) cells provides a novel way to study their lineage commitment pathway(s) and also a potential means of enriching CB with MDCs to improve prospects for DC immunotherapy following CB HSCT.
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PMID:Cord blood CD34+ cells cultured with FLT3L, stem cell factor, interleukin-6, and IL-3 produce CD11c+CD1a-/c- myeloid dendritic cells. 1799 5

V gamma 9 V delta 2 T cells exert potent cytotoxicity toward various tumor cells and adoptive transfer of V gamma 9 V delta 2 T cells is an attractive proposition for cell based immunotherapy. V gamma 9 V delta 2 T cells expanded in the presence of Zoledronate and IL-2 express CD16 (Fc gamma RIII), which raises the possibility that V gamma 9 V delta 2 T cells could be used in conjunction with tumor targeting monoclonal antibody drugs to increase antitumor cytotoxicity by antibody dependent cellular cytotoxicity (ADCC). Cytotoxic activity against CD20-positive B lineage lymphoma or chronic lymphocytic leukemia (CLL) and HER2-positive breast cancer cells was assessed in the presence of rituximab and trastuzumab, respectively. Cytotoxicity of V gamma 9 V delta 2 T cells against CD20-positive targets was higher when used in combination with rituximab. Similarly, V gamma 9 V delta 2 T cells used in combination with trastuzumab resulted in greater cytotoxicity against HER2-positive cells in comparison with either agent alone and this effect was restricted to the CD16(+)V gamma 9 V delta 2 T cell population. Our results show that CD16(+)V gamma 9 V delta 2 T cells recognize monoclonal antibody coated tumor cells via CD16 and exert ADCC similar to that observed with NK cells, even when target cells are relatively resistant to monoclonal antibodies or V gamma 9 V delta 2 T cells alone. Combination therapy involving ex vivo expanded CD16(+)V gamma 9 V delta 2 T cells and monoclonal antibodies may enhance the clinical outcomes for patients treated with monoclonal antibody therapy.
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PMID:V gamma 9 V delta 2 T cell cytotoxicity against tumor cells is enhanced by monoclonal antibody drugs--rituximab and trastuzumab. 1830 55

TGF-beta can be a potent suppressor of lymphocyte effector cell functions and can mediate these effects via distinct molecular pathways. The role of TGF-beta in regulating CD16-mediated NK cell IFN-gamma production and antibody-dependent cellular cytotoxicity (ADCC) is unclear, as are the signaling pathways that may be utilized. Treatment of primary human NK cells with TGF-beta inhibited IFN-gamma production induced by CD16 activation with or without IL-12 or IL-2, and it did so without affecting the phosphorylation/activation of MAP kinases ERK and p38, as well as STAT4. TGF-beta treatment induced SMAD3 phosphorylation, and ectopic overexpression of SMAD3 resulted in a significant decrease in IFN-gamma gene expression following CD16 activation with or without IL-12 or IL-2. Likewise, NK cells obtained from smad3(-/-) mice produced more IFN-gamma in response to CD16 activation plus IL-12 when compared with NK cells obtained from wild-type mice. Coactivation of human NK cells via CD16 and IL-12 induced expression of T-BET, the positive regulator of IFN-gamma, and T-BET was suppressed by TGF-beta and by SMAD3 overexpression. An extended treatment of primary NK cells with TGF-beta was required to inhibit ADCC, and it did so by inhibiting granzyme A and granzyme B expression. This effect was accentuated in cells overexpressing SMAD3. Collectively, our results indicate that TGF-beta inhibits CD16-mediated human NK cell IFN-gamma production and ADCC, and these effects are mediated via SMAD3.
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PMID:TGF-beta utilizes SMAD3 to inhibit CD16-mediated IFN-gamma production and antibody-dependent cellular cytotoxicity in human NK cells. 1876 31

Myeloid-derived suppressor cells (MDSC) producing arginase I are increased in the peripheral blood of patients with renal cell carcinoma (RCC). MDSC inhibit T-cell function by reducing the availability of L-arginine and are therefore considered an important tumor escape mechanism. We aimed to determine the origin of arginase I-producing MDSC in RCC patients and to identify the mechanisms used to deplete extracellular L-arginine. The results show that human MDSC are a subpopulation of activated polymorphonuclear (PMN) cells expressing high levels of CD66b, CD11b, and VEGFR1 and low levels of CD62L and CD16. In contrast to murine MDSC, human MDSC do not deplete L-arginine by increasing its uptake but instead release arginase I into the circulation. Activation of normal PMN induces phenotypic and functional changes similar to MDSC and also promotes the release of arginase I from intracellular granules. Interestingly, although activation of normal PMN usually ends with apoptosis, MDSC showed no increase in apoptosis compared with autologous PMN or PMN obtained from normal controls. High levels of VEGF have been shown to increase suppressor immature myeloid dendritic cells in cancer patients. Treatment of RCC patients with anti-VEGF antibody bevacizumab, however, did not reduce the accumulation of MDSC in peripheral blood. In contrast, the addition of interleukin-2 to the treatment increased the number of MDSC in peripheral blood and the plasma levels of arginase I. These results may provide new insights on the mechanisms of tumor-induced anergy/tolerance and may help explain why some immunotherapies fail to induce an antitumor response.
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PMID:Arginase I-producing myeloid-derived suppressor cells in renal cell carcinoma are a subpopulation of activated granulocytes. 1920 93

Human embryonic stem cells (hESCs) proliferate infinitely and are pluripotent. Only a few reports, however, describe specific and efficient methods to induce hESCs to differentiate into mature blood cells. It is important to determine whether and how these cells, once generated, behave similarly with their in vivo-produced counterparts. We developed a method to induce hESCs to differentiate into mature neutrophils. Embryoid bodies were formed with bone morphogenic protein-4, stem cell factor (SCF), Flt-3 ligand (FL), interleukin-6 (IL-6)/IL-6 receptor fusion protein (FP6), and thrombopoietin (TPO). Cells derived from the embryoid bodies were cultured on a layer of irradiated OP9 cells with a combination of SCF, FL, FP6, IL-3, and TPO, which was later changed to granulocyte-colony-stimulating factor. Morphologically mature neutrophils were obtained in approximately 2 weeks with a purity and efficiency sufficient for functional analyses. The population of predominantly mature neutrophils (hESC-Neu's) showed superoxide production, phagocytosis, bactericidal activity, and chemotaxis similar to peripheral blood neutrophils from healthy subjects, although there were differences in the surface antigen expression patterns, such as decreased CD16 expression and aberrant CD64 and CD14 expression in hESC-Neu's. Thus, this is the first description of a detailed functional analysis of mature hESC-derived neutrophils.
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PMID:Derivation of functional mature neutrophils from human embryonic stem cells. 1955 31


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