Monoclonal Antireceptor Research Articles

Time-resolved fluorescence microspheres-antibody-penicillin-binding protein assisted construction of immunochromatographic assay for sensitive detection of 22 β-lactams in milk.

Asensitive immunochromatographic assay (ICA) using time-resolved fluorescence microspheres (TRFMs) coupled with anindirect-labeling mode was developed for simultaneously determining 22 kinds of β-lactams in milk samples. The TRFMs labeled anti-receptor monoclonal antibodies (mAbs) conjugated to penicillin-binding proteins (PBPs) as ternary TRFMs-mAb-PBPs (TMP) nanoscaffolds provide excellent solubility, brightness, and stability. Thanks to the fact that they not only fully expose the binding sites of PBPs, thereby enhancing the biological affinity of PBPs towards the target, but also generated superb fluorescence signals, the versatile TMP manifested unique possibilities as efficient probes for ICA with remarkable enhancement in sensitivity in β-lactams screening. The results showed that the standard curves of the 22 varying β-lactams displayed linearity in their respective concentration ranges (R2 > 0.98), with the cutoff values of 1-100 ng/mL. Theconstructed TMP-ICA was successfully applied to the analysis of real milk, with consistent results compared with liquid chromatography-tandem mass spectrometry (LC-MS), providing an effective method for sensing β-lactams in food matrices.

OR18-01 Massively Parallel Functional Assay Of Extracellular Insulin Receptor Variants

Abstract Disclosure: V. Aslanzadeh: None. G. Brierley: None. G. Kudla: None. R.K. Semple: None. Loss-of-function mutations in the gene for the human insulin receptor, INSR, cause either autosomal dominant or autosomal recessive severe insulin resistance. Biallelic mutations produce extreme insulin resistance which is commonly fatal in infancy or childhood. A wide and growing number of mutations have been associated with disease, with few recurring mutations, and only a small subset have been studied functionally to date. Discriminating loss-of-function pathogenic alleles from insignificant variants is an important barrier to diagnosis and translational studies of novel candidate treatments. Such candidate therapies include a variety of antibody, peptide and small molecule ligands that activate the receptor in a manner distinct to insulin. These show potential to activate mutant receptors that are expressed but show impaired insulin binding or responsiveness. To address this barrier to translation we have now used massively multiplexed, Flow-Seq-based assays simultaneously to determine the effects of 14,000 human INSR extracellular domain missense variants. We assayed receptor cell surface expression, insulin binding and signal transduction using heterologous expression of mutants in mouse embryonic cells in which endogenous Insr and Igf1r genes had been knocked out or knocked down. Preliminary analysis reliably discriminates A. variants that reduce or abolish receptor cell surface expression when measured with two different monoclonal anti-receptor antibodies B. variants with preserved cell surface expression but selectively impaired binding of insulin and C. an overlapping group of variants with severely impaired signalling response to insulin but preserved response to antibody. Our assay confirmed previously studied attributes of a panel of disease-causing variants, and shows strong agreement with prior alanine scanning mutagenesis studies and structural predictions. We thus provide a rich sequence-function map for INSR variant interpretation. A prediction tool trained on known pathogenic INSR alleles is currently being developed for access by the community both to accelerate confident molecular diagnosis of newly identified rare INSR variants, and also to aid stratification of mutations according to potential for activation by non canonical INSR ligands. Presentation: Saturday, June 17, 2023

Development of a highly sensitive lateral flow immunoassay based on receptor-antibody-amorphous carbon nanoparticles to detect 22 β-lactams in milk

This study aimed to improve the sensitivity of lateral flow immunoassay (LFIA) using two strategies, including using a high sensitivity label and an indirect-labeling format, which were simultaneously applied to develop a highly sensitive LFIA to detect 22 β-lactams. In the new format, β-lactam receptors were used without any labeling, and anti-receptor monoclonal antibodies (mAbs) were labeled with amorphous carbon nanoparticles (ACNs). The new LFIA is based on the following steps: 1) screening mAbs against the receptors for antigen-antibody binding sites away from the active site of the receptors; and 2) detecting immune complexes using receptor-mAb-ACNs. The cut-off values against ampicillin, amoxicillin, benzylpenicillin, dicloxacillin, cloxacillin, oxacillin, nafcillin, cefquinome, cefoperazone, cefapirin, ceftazidime, cephalothin, cefepime, cefoxitin, cefazolin, ceftriaxone, ceftiofur, cefotaxime, cefalexin, imipenem, meropenem, and ertapenem were 1, 2, 2, 10, 10, 10, 10, 3, 3, 3, 5, 10, 10, 20, 20, 20, 30, 30, 100, 10, 15, and 15 ng/mL, respectively, which is significantly lower than that of receptor-mAb-colloidal gold-LFIA using the same immune reagents.

Olaratumab plus anthracyline in advanced/metastatic soft tissue sarcoma: Data of real-world utilization in Austria.

e22550 Background: Olaratumab is a humanized monoclonal anti platelet-derived growth factor receptor α antibody that has been approved in combination with doxorubicin for the treatment of patients with metastatic soft tissue sarcoma (STS). The purpose of this retrospective study was to assess the clinical efficacy in STS patients treated with olaratumab in a real-world setting in Austria. Methods: Retrospectively collected, longitudinal data from patients treated between November 2016 and September 2018 at 9 Austrian centers were obtained from respective medical charts. Eligible patients were all patients who received at least one dose of olaratumab. Parameters of most interest collected were response rates, progression-free survival (PFS) and overall survival (OS). Results: Altogether 55 patients were included into analysis. Median age was 58 years. In total, 65.5% (n = 36), 21.8% (n = 12) and 12.7% (n = 7) received olaratumab as first-, second- or ≥ third-line treatment, respectively. Olaratumab was administered either in combination with doxorubicin (81.8%, n = 45) or liposomal doxorubicin (16.4%, n = 9); 1 patient received olaratumab as upfront monotherapy. Median PFS and OS were 2.6 and 11.4 months. The objective response rate was 11.4 % and the disease control rate was 40.9 %. Conclusions: In this real-world analysis outcome was less pronounced compared to the results of the Phase Ib/II approval trial ( Tap WD et al. Lancet 2016). Thus, the results of the ongoing phase III trial (NCT02451943) are urgently needed to confirm the efficacy of the combination of olaratumab and doxorubicin in STS patients.

High-Dimensional Phenotypic Mapping of Human Dendritic Cells Reveals Interindividual Variation and Tissue Specialization

Given the limited efficacy of clinical approaches that rely on exvivo generated dendritic cells (DCs), it is imperative to design strategies that harness specialized DC subsets in situ. This requires delineating the expression of surface markers by DC subsets among individuals and tissues. Here, we performed a multiparametric phenotypic characterization and unbiased analysis of human DC subsets in blood, tonsil, spleen, and skin. We uncovered previously unreported phenotypic heterogeneity of human cDC2s among individuals, including variable expression of functional receptors such as CD172a. We found marked differences in DC subsets localized in blood and lymphoid tissues versus skin, and a striking absence of the newly discovered Axl+ DCs in the skin. Finally, we evaluated the capacity of anti-receptor monoclonal antibodies to deliver vaccine components to skin DC subsets. These results offer a promising path for developing DC subset-specific immunotherapies that cannot be provided by transcriptomic analysis alone.

Comparison of cell-based and non-cell-based assay platforms for the detection of clinically relevant anti-drug neutralizing antibodies for immunogenicity assessment of therapeutic proteins

Anti-drug neutralizing antibodies (NAbs) formed due to unwanted immunogenicity of a therapeutic protein point towards a mature immune response. NAb detection is important in interpreting the therapeutic's efficacy and safety in vivo. In vitro cell-based NAb assays provide a physiological system for NAb detection, however are complex assays. Non-cell-based competitive ligand binding (CLB) approaches are also employed for NAb detection. Instead of cells, CLB assays use soluble receptor and conjugated reagents and are easier to perform, however have reduced physiological relevance. The aim of this study was to compare the performance of CLB assays to established cell-based assays to determine the former's ability to detect clinically relevant NAbs towards therapeutics that (i) acted as an agonist or (ii) acted as antagonists by binding to a target receptor.We performed a head-to-head comparison of the performance of cell-based and CLB NAb assays for erythropoietin (EPO) and two anti-receptor monoclonal antibodies (AMG-X and AMG 317). Clinically relevant NAb-positive samples identified previously by a cell-based assay were assessed in the corresponding CLB format(s). A panel of 12 engineered fully human anti-EPO monoclonal antibodies (MAbs) was tested in both EPO NAb assay formats. Our results showed that the CLB format was (i) capable of detecting human anti-EPO MAbs of differing neutralizing capabilities and affinities and (ii) provided similar results as the cell-based assay for detecting NAbs in patient samples. The cell-based and CLB assays also behaved comparably in detecting NAbs in clinical samples for AMG-X. In the case of anti-AMG 317 NAbs, the CLB format failed to detect NAbs in more than 50% of the tested samples. We conclude that assay sensitivity, drug tolerance and the selected assay matrix played an important role in the inability of AMG 317 CLB assays to detect clinically relevant NAbs.

Negative effects of trastuzumab adjuvant chemotherapy on cardiac mechanics. role of specific myocardial layers

Background: Trastuzumab (TZB), an anti HER-2 receptor monoclonal antibody, has been shown to be very effective in patients with breast cancer overexpressing HER-2. It has a mild cardiac toxicity, which may increase when administered in combination with anthracyclines. Anthracycline treatment showed to induce a myocardial overexpression of HER-2 receptors. Myocardial deformation indexes associated with Speckle Tracking (ST) myocardial imaging have shown to be very sensitive identifying left ventricular (LV) dysfunction in this setting. The aim of the study is to assess the effect of TZB therapy on specific myocardial layers after anthracycline treatment. Patients and methods: The study was designed to assess TZB-induced cardiac damage by ST technique in patients with HER-2 positive breast cancer treated with TZB sequentially after Epirubicin treatment. Inclusion criteria: 18–70 yo, histologically confirmed HER-2 positive breast cancer, candidates for TZB-based regimen; LVEF ≥55%; ECOG PS score 0-2, no history of cardiac disease. The following assessments were carried out at baseline, after Epirubucin treatment, at each TZB treatment and every 3 months during 1 year follow-up: ECOG PS score, conventional echocardiography and 2D/3D ST parameters (circumferential and longitudinal S and SR, LV torsion) Results: At Dec 2012, 38 patients (mean ± SD age 51±10 yo) have been enrolled. A significant reduction of the longitudinal peak of SR (0.71±0.16 s-1 vs 0.81±0.14 s-1; p<0.05) was found after Epi treatment, while a significant increase of circumferential function (1.03±0.31 s-1 vs 0.71±0.13 s-1; p<0.01) was evidenced. From the third dose of TZB a maked reduction of the circumferential function (0.69±0.18 s-1 vs 1.03±0.31 s-1; p<0.01) and of LV rotation (15.26±5.38 vs 22.88±6.41; p<0.001) was found, while no further reduction in the longitudinal function was determined. Conclusions: The aim of the study was that to ascertain the amount, timing and type of the pre-clinical cardiac dysfunction induced by TZB when administered after anthracyclines. We evidenced that after anthracyclines longitudinal function is impaired while a compensatory increase of LV circumferential function and of LV torsion is present. After TZB we showed mostly a toxicity of mid and sub epicardial fibres, responsible mainly for the circumferential function and of the torsion of the left ventricle. These effects could be related to the higher toxicity of TZB on the hyperactive myocardial fibres after Epi treatment. Follow up data will show if this mid and sub epicardial myocardial impairment will persist over time.

Phase II trial of preoperative radiotherapy (RT) and panitumumab (PAN) in KRAS wild type (wt) rectal cancer (RC).

e14060 Background: The addition of anti Epidermal Growth Factor Receptor (EGFR) monoclonal antibodies (mabs) to preoperative chemoradiation in RC has produced low pathological complete response (pCR) rate. The postulated reasons for the poor outcome are: lack of patient selection, suboptimal treatment sequencing, and potential negative interaction between anti EGFR mabs and chemotherapy (CT) when used concurrently as radiosensitizers. Given these issues, we conducted a phase II trial of PAN in combination with preoperative RT in Kras wt RC. Methods: We studied several treatment sequences in murine models of Kras wt human colorectal cancer. Next, we used our preclinical results to design the treatment schedule of the phase II trial. PAN (6mg/kg/q2w) was combined with RT (45 Gy) to treat T3-4, Kras wt RC. Surgery was done 6-8 weeks after the end of RT. The primary endpoint, the pCR rate on surgical specimen, was assessed centrally (Simon: H0=5%, H1=17%, α=0.05, β=0.2). Results: In our murine models, the addition of anti EGFR mabs to RT significantly improved response when anti EGFR mabs were started during RT and extended after the end of RT (p&lt;0.05). No benefit was found when anti EGFR mabs were given before the start of RT. In the phase II trial, we therefore started RT on day 1 and introduced PAN 7 days later (day 8). After RT ended (day 36), PAN treatment was continued to day 50. To fully explore PAN’s potential as radiosensitizer, CT was not given during RT but postoperatively. 19 patients were evaluable for pCR. 47% of tumours were cT3N+. Hypomagnesemia (16%) and hypophosphatemia (16%) were most common grade ≥3 toxicities. As no pCR was found, the study was closed prematurely for lack of efficacy according to the statistical rule. 7 patients (41%) had &gt;50% pathological tumour regression (grade 3 Dworak) and 12 (70%) showed &gt;2mm of tumour-free circumferential resection margin. Conclusions: Preclinical data confirm the need of optimal treatment sequencing to potentiate synergism between anti EGFR mabs and RT. However, the pCR rate in our phase II trial remains low despite adequate patient selection and optimized study design. Thus, we do not recommend the concurrent use of anti EGFR mabs and RT in the neoadjuvant treatment of RC.

Abstract 599: TMPRSS2-ERG gene fusion sensitizes VCaP human prostate tumors to the fully human anti-IGF-IR monoclonal antibody SCH 717454

Abstract A gene fusion of the androgen-regulated gene transmembrane protease, serine 2, (TMPRSS2) to the v-ets erythroblastosis virus E26 oncogene homolog (avian), ERG, of the erythroblast transformation-specific (ETS) family of transcription factors is a recently discovered genetic alteration in prostate cancer. Expression of the TMPRSS2-ERG fusion in prostate cancer patients is associated with an aggressive clinical phenotype and an early recurrence of the disease. Interestingly, in TMPRSS2-ERG positive prostate cancer cells, expression of this gene fusion is regulated by both estrogens and androgens. However, while the hormonal regulation of this fusion has been established the downstream effects of TPRSS2-ERG fusion gene have not been determined. Quantitative PCR analyses of 134 cancer cell lines, including 10 prostate cancer models, for expression of the TMPRSS2-ERG gene fusion showed that it was only present in VCaP, DuCaP, and NCI-H660 prostate cancer cells. We report here that VCaP human prostate cancer cells and tumor xenografts are sensitive to treatment with the fully human anti insulin-like growth factor-I receptor (IGF-IR) monoclonal antibody SCH 717454. After 28 days of treatment, single-agent SCH 717454 (0.5 mg, ip, 2 × week) caused complete inhibition of VCaP tumor growth. MDA PCa-2b, 22Rv1, DU-145, and LNCaP human prostate cancer tumor xenografts (negative for expression of the TMPRSS2-ERG gene fusion) did not respond to treatment with SCH 717454. Further, PTEN null NCI-H660 prostate tumors that also express the TMPRSS2-ERG gene fusion also did not respond to treatment with SCH 717454. When male SCID mice bearing established VCaP prostate cancer tumor xenografts were treated with the combination of surgical castration and SCH 717454 we observed 100% tumor regressions in all of the animals so that after 28 days of treatment there were no detectable tumors. When SCH 717454 was combined with the antiandrogen bicalutamide (50 mpk, po, bid), VCaP tumors regressed by 42%. That the combination of SCH 717454 and castration produced superior anti-tumor activity than the combination of SCH 717454 and bicalutamide provides further evidence that expression of the TMPRSS2-ERG gene fusion in VCaP prostate cancer tumors is regulated by both estrogens and androgens. TMPRSS2-ERG gene fusion expressing prostate cancer represents a new sub-classification of human prostate cancer. The precise role that the TMPRSS2-ERG fusion plays in the biology of human prostate cancer remains to be fully determined. These data indicate that PTEN wild-type VCaP prostate tumors that express the TMPRSS2-ERG gene fusion are sensitive to anti-IGF-IR treatment with SCH 717454 and that combining SCH 717454 with an androgen ablation therapy results in impressive anti-tumor activity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 599. doi:10.1158/1538-7445.AM2011-599

Effect of bevacizumab on postoperative adhesion formation in a rat uterine horn adhesion model and the correlation with vascular endothelial growth factor and Ki-67 immunopositivity

We investigated whether adhesion formation is prevented by the inhibition of angiogenesis in a rat uterine horn adhesion model. A single-dose of bevacizumab was effective in preventing postoperative intraperitoneal adhesion formation among 30 Wistar albino rats that underwent serosal injury by use of a standard technique after laparotomy with intraperitoneal bevacizumab.

The inhibition of the interaction between the anthrax toxin and its cellular receptor by an anti-receptor monoclonal antibody

The high affinity binding of the anthrax protective antigen (PA) to one of its receptors, capillary morphogenesis protein 2 (CMG2), is essential for the intoxication process of anthrax toxin. To acquire novel research tools to study the PA–CMG2 interaction, we generated several anti-CMG2 monoclonal antibodies (MAbs). We demonstrated that one of the MAbs, 4B5, could inhibit PA–CMG2 binding and could also protect the sensitive cells against an anthrax lethal toxin challenge. We identified the epitope recognized by 4B5 and confirmed that the key residues of the epitope were the residues 119YI–LK 125 of CMG2. Based on our results, we propose that 4B5 binds to the E122 pocket of CMG2 and interrupts the interaction between the pocket and the PA 2β3–2β4 loop. To our knowledge, this is the first report to illustrate that an anti-CMG2 antibody could inhibit the PA–CMG2 interaction and therefore interfere with the intoxication of anthrax toxin.

Deficiency of Immunophilin FKBP52 Promotes Endometriosis

Endometriosis is a common gynecological disease that affects approximately 10% of women of childbearing age. It is characterized by endometrial growth outside the uterus and often results in inflamed lesions, pain, and reduced fertility. Although heightened estrogenic activity and/or reduced progesterone responsiveness are considered to be involved in the etiology of endometriosis, neither the extent of their participation nor the underlying mechanisms are clearly understood. Heterogeneous uterine cell types differentially respond to estrogen and progesterone (P(4)). P(4), primarily acting via its nuclear receptor (PR), activates gene transcription and impacts many reproductive processes. Deletion of Fkbp52, an immunophilin cochaperone for PR, results in uterine-specific P(4) resistance in mice, creating an opportunity to study the unique aspects of P(4) signaling in endometriosis. Here we explored the roles of FKBP52 in this disease using Fkbp52(-/-) mice. We found that the loss of FKBP52 encourages the growth of endometriotic lesions with increased inflammation, cell proliferation, and angiogenesis. We also found remarkable down-regulation of FKBP52 in cases of human endometriosis. Our results provide the first evidence corroborated by genetic studies in mice for a potential role of an immunophilin cochaperone in the etiology of human endometriosis. This investigation is highly relevant for clinical application, particularly because P(4) resistance is favorably indicated in endometriosis and other gynecological diseases.

Production of the Soluble Form of KIT, s-KIT, Abolishes Stem Cell Factor-Induced Melanogenesis in Human Melanocytes

The signaling of stem cell factor (SCF) and its receptor KIT (membrane-bound KIT; m-KIT) plays an important role in melanocyte development, survival, proliferation, and melanogenesis. It has been demonstrated in other systems that a soluble form of m-KIT released from the cell surface (s-KIT) regulates SCF signaling, although there have been no reports pertaining to the existence and the biological role of s-KIT in melanocytes. In this study, we therefore examined the involvement of s-KIT in melanogenesis. Western blotting analysis revealed that treatment with phorbol 12-myristate-13-acetate (PMA) or 4-aminophenylmercuric acetate (APMA) induced s-KIT production in cultured human melanocytes. Inhibitors of tumor necrosis factor-alpha-converting enzyme (TACE) and metalloproteinases (MMPs) muted this release of s-KIT into the media. Human recombinant s-KIT added to melanocytes inhibited SCF-induced phosphorylation of m-KIT, resulting in suppression of SCF-induced melanogenesis. Additionally, APMA-induced s-KIT production abolished SCF-induced melanogenesis as effectively as a KIT-neutralizing antibody. Concomitantly, APMA and TACE inhibitors significantly decreased and increased melanin synthesis, respectively, in an in vitro skin model. Taken together, these findings provided an insight into the elaborate mechanism of SCF/m-KIT signaling in human melanocytes and suggested that production of s-KIT contributes to the regulation of human skin pigmentation. Journal of Investigative Dermatology (2008) 128, 1763-1772; doi:10.1038/jid.2008.9; published online 31 January 2008.

205 POSTER AMG 479, a fully human anti IGF-1 receptor monoclonal antibody, enhances the response of established colon and pancreatic xenografts to chemotherapeutic agents

205 POSTER AMG 479, a fully human anti IGF-1 receptor monoclonal antibody, enhances the response of established colon and pancreatic xenografts to chemotherapeutic agents

Oncogenic growth factor receptors: implications for signal transduction therapy

Growth factors of the EGF family and their respective ErbB/HER receptor tyrosine kinases underlie many landmarks of tumor cells, including excessive growth, invasive behavior and attraction of blood vessels. Enhanced expression of ErbB proteins, existence of permanently active receptor mutants and occurrence of autocrine loops are frequently observed in human cancer, and in some cases they associate with poor disease outcome. The four ErbB proteins and their 11 ligands act within a layered signaling network coordinated by ErbB-2/HER2, the most oncogenic family member. Drugs that intercept signals emanating from ErbB-2 and ErbB-1 are already in routine clinical application. Here we review three major strategies to develop new ErbB-targeted therapies. These are monoclonal anti-receptor antibodies, specific tyrosine kinase inhibitors and antagonists of heat shock protein 90. The underlying mechanisms are critically examined, with an emphasis on potential drug combinations, which hold promise for enhanced clinical efficacy.

Results of a phase I trial of the humanized anti epidermal growth factor receptor (EGFr) monoclonal antibody emd 72000 in patients with EGFr expressing solid tumors

Results of a phase I trial of the humanized anti epidermal growth factor receptor (EGFr) monoclonal antibody emd 72000 in patients with EGFr expressing solid tumors

Role of Insulin Receptor Dimerization Domains in Ligand Binding, Cooperativity, and Modulation by Anti-receptor Antibodies

To define the structures within the insulin receptor (IR) that are required for high affinity ligand binding, we have used IR fragments consisting of four amino-terminal domains (L1, cysteine-rich, L2, first fibronectin type III domain) fused to sequences encoded by exon 10 (including the carboxyl terminus of the alpha-subunit). The fragments contained one or both cysteine residues (amino acids 524 and 682) that form disulfides between alpha-subunits in native IR. A dimeric fragment designated IR593.CT (amino acids 1-593 and 704-719) bound (125)I-insulin with high affinity comparable to detergent-solubilized wild type IR and mIR.Fn0/Ex10 (amino acids 1-601 and 650-719) and greater than that of dimeric mIR.Fn0 (amino acids 1-601 and 704-719) and monomeric IR473.CT (amino acids 1-473 and 704-719). However, neither IR593.CT nor mIR.Fn0 exhibited negative cooperativity (a feature characteristic of the native insulin receptor and mIR.Fn0/Ex10), as shown by failure of unlabeled insulin to accelerate dissociation of bound (125)I-insulin. Anti-receptor monoclonal antibodies that recognize epitopes in the first fibronectin type III domain (amino acids 471-593) and inhibit insulin binding to wild type IR inhibited insulin binding to mIR.Fn0/Ex10 but not IR593.CT or mIR.Fn0. We conclude the following: 1) precise positioning of the carboxyl-terminal sequence can be a critical determinant of binding affinity; 2) dimerization via the first fibronectin domain alone can contribute to high affinity ligand binding; and 3) the second dimerization domain encoded by exon 10 is required for ligand cooperativity and modulation by antibodies.

Hyperthermic stress stimulates the association of both constitutive and inducible isoforms of 70 kDa heat shock protein with rat liver glucocorticoid receptor

Glucocorticoid hormone receptor exists in the cytoplasm of target cells in the form of dynamic multiprotein heterocomplexes with heat shock proteins Hsp90 and Hsp70, and additional components of the molecular chaperone machinery. Whole body hyperthermic stress was previously shown to induce alterations in protein composition of these complexes increasing the share of Hsp70, but participation of individual Hsp70 family members was not investigated. In the present study the association of glucocorticoid receptor with constitutive and inducible forms of Hsp70 in the liver cytosol of rats exposed to 41 °C whole body hyperthermic stress was examined. Immunoprecipitation of glucocorticoid receptor heterocomplexes by monoclonal anti-receptor antibody (BuGR2) followed by quantitative immunoblotting revealed the presence of both nucleocytoplasmic Hsp70 family members, constitutive—Hsc70 and inducible—Hsp72, within the complexes. Immediately after the stress only Hsc70 was found in association with glucocorticoid receptor. However, after the induction of Hsp72 by stress, its appearance within the glucocorticoid receptor heterocomplexes was also recorded and the presence of both Hsp70 forms within the heterocomplexes was evident by the end of examined 24 h period after the stress. This study confirms that heat stress affects protein composition of rat liver glucocorticoid receptor heterocomplexes increasing the share of Hsp70 and shows that this increase could be equally ascribed to constitutive and inducible forms of Hsp70.

The epidermal growth factor receptor as a target for cancer therapy.

Epidermal growth factor (EGF) receptors are expressed at high levels in about one third of epithelial cancers, and autocrine activation of EGF receptors appears to be critical for the growth of many tumors. We hypothesized that blockade of the binding sites for EGF and transforming growth factor-alpha on EGF receptors with an antireceptor monoclonal antibody (mAb) might be an effective anti-cancer therapy. We produced murine mAb 225 against EGF receptors and demonstrated blockade of receptor function, as well as inhibition of cell growth in cultures and in nude mouse xenografts. mAb C225 is the human:murine chimeric version of mAb 225. Cell cycle inhibition occurred in G(1) phase, and was due to upregulation of p27(Kip1), resulting in inhibition of cyclin E/cyclin dependent kinase-2 activity and hypophosphorylation of Rb. In addition, the amount and/or activities of a number of proapoptotic molecules were enhanced. The antitumor activity in vivo against xenografts was at least partly attributable to reduced vascularization, resulting from decreased vascular endothelial growth factor and basic fibroblast growth factor production by the tumor cells. Metastasis of xenografts was curtailed with mAB C225 treatment, accompanied by a decrease in tumor production of MMP-9. Further studies showed that mAbs 225 and C225 enhanced the cytotoxicity of chemotherapy against xenografts of a variety of human cancer cell lines. Well established xenografts resistant to either mAb or drug treatment alone were eradicated by the combination therapy. Drugs for which this has been demonstrated include doxorubicin, paclitaxel, cisplatin, and topotecan. Antibody treatment also potentiated the responsiveness of human tumor xenografts to radiation therapy. These findings led to clinical trials of human:murine chimeric mAb C225 in combination with chemotherapy or radiotherapy. Results from phase I and II trials involving more than 500 patients are quite promising, in particular in advanced head and neck cancer treated with C225 plus cisplatin or radiation, in advanced colon cancer treated with C225 plus CPT-11, and in advanced pancreatic cancer treated with C225 plus gemcitabine. Phase III trials are now underway.

Localization of a binding site for herpes simplex virus glycoprotein D on herpesvirus entry mediator C by using antireceptor monoclonal antibodies.

The human herpesvirus entry mediator C (HveC), also known as the poliovirus receptor-related protein 1 (PRR1) and as nectin-1, allows the entry of herpes simplex virus type 1 (HSV-1) and HSV-2 into mammalian cells. The interaction of virus envelope glycoprotein D (gD) with such a receptor is an essential step in the process leading to membrane fusion. HveC is a member of the immunoglobulin (Ig) superfamily and contains three Ig-like domains in its extracellular portion. The gD binding site is located within the first Ig-like domain (V domain) of HveC. We generated a panel of monoclonal antibodies (MAbs) against the ectodomain of HveC. Eleven of these, which detect linear or conformational epitopes within the V domain, were used to map a gD binding site. They allowed the detection of HveC by enzyme-linked immunosorbent assay, Western blotting, and biosensor analysis or directly on the surface of HeLa cells and human neuroblastoma cell lines, as well as simian Vero cells. The anti-HveC V-domain MAbs CK6, CK8, and CK41, as well as the previously described MAb R1.302, blocked HSV entry. Their binding to soluble HveC was blocked by the association of gD with the receptor, indicating that their epitopes overlap a gD binding site. Competition assays on an optical biosensor showed that CK6 and CK8 (linear epitopes) inhibited the binding of CK41 and R1.302 (conformational epitopes) to HveC and vice versa. Epitope mapping showed that CK6 and CK8 bound between residues 80 and 104 of HveC, suggesting that part of the gD binding site colocalizes in the same region.