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Biomedical subjects

Bruce W S Robinson

Publications and source records attributed to Bruce W S Robinson.

At least 19 recordsLinked to original sources
PubMed2006

A novel SV40 TAg transgenic model of asbestos-induced mesothelioma: malignant transformation is dose dependent.

Although it has been clear for >40 years that mesothelioma can be caused by asbestos, not all patients with this disease have a history of asbestos exposure. Other factors, including non-asbestos fibers and ionizing radiation, are known to cause malignant transformation of mesothelial cells. In addition, it is likely that genetics will play some role in susceptibility. Recently, it has been suggested that SV40 viral oncogenes could contribute to the carcinogenicity of asbestos. To better understand the role of SV40, we used the mesothelin promoter to construct MexTAg mice that express SV40 large T antigen (TAg) in the mesothelial compartment. We generated four MexTAg lines that carry high, intermediate, and low copy numbers of the transgene. All of these mice show a relatively low level of spontaneous tumor development. High-copy, 299h mice rapidly developed mesotheliomas when exposed to asbestos, and these tumors were faster growing and more invasive than those developing in wild-type and single-copy (266s) mice. In addition, we found a direct relationship between transgene copy number and survival after exposure to asbestos. A single copy of TAg was sufficient to immortalize mesothelial cells in vitro, but these cells did not show evidence of malignant transformation. In contrast, cell lines developed from mesothelial cells of animals carrying multiple copies of TAg were growth factor independent and could be cloned at limiting dilution in soft agar. These data provide the first in vivo demonstration of co-carcinogenicity between SV40 and asbestos.

Animals↗
PubMed2006

A molecular diagnostic test for distinguishing lung adenocarcinoma from malignant mesothelioma using cells collected from pleural effusions.

PURPOSE: Patients with malignant mesothelioma or adenocarcinoma of the lung often present with respiratory complications associated with a malignant pleural effusion. Distinguishing between these malignancies is frequently problematic, as many of the clinical, cytologic, and histologic features of the diseases overlap. Following cytologic analysis of pleural effusions, subsequent confirmatory tissue biopsies involve increased patient morbidity and expense. We have therefore designed a gene expression-based test to classify the primary tumor causing a malignant pleural effusion, using cells collected from the effusion itself. EXPERIMENTAL DESIGN: We have used microarray data for 190 lung adenocarcinomas and 33 malignant mesotheliomas to identify genes differentially expressed between the two diseases. Genes expressed in normal mesothelial cells were removed, allowing the development of a PCR-based test to measure the expression of genes that discriminate between mesothelioma and lung adenocarcinoma from cytology specimens. RESULTS: Applying an real-time PCR-based assay involving 17 genes to 13 independent samples from biopsy-proven malignant mesothelioma and lung adenocarcinomas resulted in the correct identification of all samples. CONCLUSIONS: We have developed a test that is able to distinguish between lung adenocarcinoma and mesothelioma in cells collected from pleural effusions.

Adenocarcinoma↗
PubMed2006

Combined chemoimmunotherapy of solid tumours: improving vaccines?

Cytotoxic chemotherapy not only affects the tumour but also targets dividing lymphocytes, the very cells required to develop an immune response. Hence, chemo- and immunotherapy have been seen as antagonistic. It is now clear that the way a chemotherapeutic drug kills a tumour cell determines how that dying cell interacts with the immune system and whether the interaction leads to an immune response. Chemotherapy also depletes regulatory T cells, potentially enhancing immune responses. Furthermore, lymphodepletion triggers homeostatic T cell reconstitution, creating new populations of pre-T cells that need education in the thymic environment. Post-chemotherapy immune system reconstitution may provide a unique opportunity for therapeutic intervention by shaping the repertoire towards reactivity to tumour antigens. An understanding of the underlying cellular and immunological events in both animal models and patients undergoing chemotherapy will guide decisions about which immunomodulatory approaches may be effective with different cytostatic drugs and hence to develop appropriate scheduling for integration of the treatment modalities.

Animals↗
PubMed2006

ERK1/2 and p38 MAP kinase control MMP-2, MT1-MMP, and TIMP action and affect cell migration: a comparison between mesothelioma and mesothelial cells.

Pleural malignant mesothelioma is a locally aggressive tumor of mesothelial cell origin. In other tumor types high expression of matrix metalloproteinase (MMP)-2, together with membrane-type1-MMP (MT1-MMP), and low levels of the tissue inhibitor of MMP (TIMP)-2 have been correlated with aggressive tumor progression and low survival rates. Therefore, we compared the expression and activation of these three factors and their regulation by two mesothelioma associated growth factors, platelet-derived growth factor (PDGF)-BB, and transforming growth factor (TGF)-beta1 in six human mesothelioma and one mesothelial cell line. Polymerase chain reaction (PCR), immunoblotting, zymography, and small inhibitory RNAs (siRNA) were used to study gene expression, protein activation, and signal transduction. To proof the relevance of our in vitro data immunohistochemistry was performed in tissue sections. PDGF-BB induced, while TGF-beta1 inhibited cell proliferation. PDGF-BB was a chemoattractant for mesothelial cells, and its effect was increased in the presence of TGF-beta1. TGF-beta1 stimulated the de novo synthesis of pro-MMP-2 in both cell types. Pro-MMP-2 synthesis involved p38 MAP kinase. In cell culture and tissue sections only mesothelial cells expressed MT1-MMP. Migration of mesothelioma cells was dependent on the presence of MT1-MMP. Migration, but not proliferation of mesothelioma cells was inhibited by oleoyl-N-hydroxylamide, TIMP-2, and siRNA for MT1-MMP. Our data suggest that in mesothelioma cells the phosphorylation of p38 MAP kinase is deregulated and is involved in pro-MMP-2 expression. Mesothelioma progression depends on an interaction with mesothelial cells that provide MT1-MMP necessary to activate pro-MMP-2 to facilitate migration through an extracellular matrix (ECM) layer.

Becaplermin↗
PubMed2005

Functional endogenous cytotoxic T lymphocytes are generated to multiple antigens co-expressed by progressing tumors; after intra-tumoral IL-2 therapy these effector cells eradicate established tumors.

Tumors contain many antigens that may be recognized by the immune system. It is not known whether these antigens, and the epitopes within these antigens, can all be recognized by the anti-tumor immune response or if such responses are restricted to a few dominant epitopes. Effector function of endogenous cytotoxic T lymphocytes (CTL) generated during tumor progression has previously been assessed by indirect, ex vivo assays, which often focused on a single antigen. Therefore, we evaluated the endogenous in vivo CTL response to multiple neo tumor antigens using murine Lewis lung carcinoma tumor cells transfected with ovalbumin or a polyepitope construct. Both express multiple MHC class I-restricted epitopes. Ovalbumin contains a known hierarchy of epitopes for given MHC molecules, whilst the polyepitope expresses a number of dominant epitopes. We show that as tumors progress, potent effector CTL are generated in vivo that are restricted to dominant epitopes; we did not see the responses to subdominant or cryptic epitopes. Our data show that the CTL recognizing tumor antigens vary in their lytic capacity, as the CTL responding to two of the four epitopes were particularly potent killers. The presence of these effector CTLs did not prevent tumor growth. However, intra-tumoral IL-2 treatment altered the potency, but not the hierarchy, of these CTL such that they mediated tumor regression. These results have implications for immunotherapy protocols.

Animals↗
PubMed2005

Partial, but not complete, tumor-debulking surgery promotes protective antitumor memory when combined with chemotherapy and adjuvant immunotherapy.

Resection alone is rarely curative for advanced tumors, but the outcome generally improves with adjuvant therapy. We have previously shown that a combination of traditional chemotherapy (gemcitabine) and immunotherapy (anti-CD40/FGK-45) without surgery is synergistic and can lead to long-term cure when applied to small tumors. Such cured animals have immunologic memory and are protected from rechallenge. Here we investigate the effectiveness of combination chemotherapy and immunotherapy after partial or complete surgical debulking of large tumors. We found that complete resection followed by combination chemotherapy/immunotherapy led to a high rate of cure (>80%) but failed to induce a long-term, tumor-specific memory. Partial debulking followed by combination therapy elicited the same proportion of cured animals but in contrast to complete resection, a memory response was invoked. We postulate that chemotherapy induced apoptosis of the residual tumor cells following incomplete resection is absolutely required for the induction of long-term immunologic memory.

Animals↗
PubMed2005

Detection of malignant mesothelioma in asbestos-exposed individuals: the potential role of soluble mesothelin-related protein.

Malignant mesothelioma (MM) is strongly associated with asbestos exposure. Measurement of soluble mesothelin-related protein (SMRP) levels in the serum may prove valuable as an adjunct to current tests for the diagnosis of MM and for monitoring MM patients for the early detection of disease recurrence. SMRP measures also may be useful in an overall screening program for MM because early results show that some individuals have elevated levels 1 to 4 years before symptom development. Although individuals with occupational and nonoccupational asbestos exposure are justifiably concerned about their risk of developing MM, consideration must be given to the complex issues surrounding screening for this disease, and a more substantial evaluation of the SMRP marker must be undertaken before deciding to promote a screening program.

Asbestos↗
PubMed2005

Soluble mesothelin-related protein--a blood test for mesothelioma.

Identification of tumor marker for mesothelioma (MM) might prove useful in diagnosis as well as for monitoring tumor in response to therapy and for screening at-risk individuals. We tested the hypothesis that soluble mesothelin-related protein (SMRP), a mesothelin family member, in the serum would be such a marker. Our data show that determination of SMRP in serum is a marker of MM with a sensitivity of sensitivity 83% and specificity 95% in the first 48 MM patients tested. Changes in serum SMRP levels parallel clinical course/tumor size and SMRP is elevated in 75% of patients at diagnosis. SMRP should also be useful for monitoring disease progression, and importantly, may prove useful for screening asbestos-exposed individuals for early MM.

Adult↗
PubMed2005

Immunotherapy and chemotherapy--a practical partnership.

This article discusses how recent data have altered the way we understand how dying tumour cells, particularly those killed by chemotherapy, engage with antitumour immune responses. These data have significant implications for the development of new protocols combining chemotherapy with immunotherapy, indicating an exciting potential for therapeutic synergy with general applicability to many cancer types.

Animals↗
PubMed2005

Gene therapy of mesothelioma.

Despite improved diagnostic skills and new chemotherapeutic regimens, malignant mesothelioma (MM) remains a pathological disease with survival expectations after diagnosis remaining < 1 year. As the incidence of this disease has yet to peak, there is a pressing need for new therapeutic approaches. One such approach is gene therapy, which inserts 'therapeutic' genes into (generally) tumour cells seeking to induce tumour regression via a number of different theoretical mechanisms. This approach may be particularly relevent for mesothelioma as it is localised to body cavities and is readily accessible for biopsy sampling or for gene delivery. Furthermore, as MM patients rarely die from distant metastases, treating the primary tumour site may result in significant symptomatic and survival benefit. Herein, the paper discusses past, present and future views on gene therapy in the treatment of MM.

Animals↗
PubMed2004

Cutting edge: tumor-specific CTL are constitutively cross-armed in draining lymph nodes and transiently disseminate to mediate tumor regression following systemic CD40 activation.

The cross-arming of effector CTL in response to cross-presented tumor Ags is predicted to fail in the absence of CD40 stimulation. However, questions remain regarding the role of CD40 signaling and additional CD4+ T cell-derived signals in this process. To address this, we have analyzed the cross-arming of tumor-specific CTL effectors in vivo in a mouse model of established tumor and tumor regression following CD40 activation. We found that tumor-specific CTL were constitutively cross-armed in tumor-draining lymph nodes during tumor growth and that systemic CD40 activation did not alter CTL cross-arming in the tumor-draining lymph nodes. Rather, CD40 activation induced peripheral dissemination of tumor-specific CTL effectors that required continual CD40 stimulation to maintain peripheral CTL and tumor regression. These data indicate that CD40 activation enhances the peripheral survival of constitutively cross-armed CTL and that persistent CD4+ T cell signals are required for their long-term activity.

Animals↗
PubMed2004

CD4+ T cells cross-compete for MHC class II-restricted peptide antigen complexes on the surface of antigen presenting cells.

CD4(+) T cells are activated upon recognition of peptide antigen in the context of MHC class II molecules, expressed by specialized APC. In this study, we show that CD4(+) T cells cross-compete for antigenic complexes on the surface of APC, inhibiting activation of other potentially reactive T cells of the same and differing specificities. T cells with either a higher affinity receptor for antigen or which have undergone prior activation compete more efficiently than low affinity or resting T cells. This implies that T-cell avidity for the APC is primarily responsible for the competitive advantage. We also provide evidence that the mechanism for competition is steric hindrance of the surface of the APC, rather than T-cell-mediated sequestration or internalization of antigenic complexes. This is because removal of competing T cells restores the antigenic potential of the APC, and APC fixation does not abrogate competition. Demonstration that competition for access to APC can also occur in vivo suggests that this process may represent a physiologically important mechanism for influencing the quality and quantity of CD4(+) T-cell responses.

Animals↗
PubMed2004

Current chemotherapeutic treatment of malignant pleural mesothelioma.

Malignant pleural mesothelioma is an aggressive malignancy which is almost always fatal; median survival is usually < 1 year. Most patients present with symptoms including pain, dyspnoea, pleural effusions and chest wall masses. Until recently, there has been no effective treatment which can improve symptoms and prolong survival. This article reviews recent developments in the treatment of mesothelioma, particularly advances in drug therapy and the use of the current most active drug combination: pemetrexed and cisplatin. Pemetrexed is a novel antifolate drug with multiple enzyme targets. The combination of pemetrexed and cisplatin demonstrated a survival advantage over cisplatin alone in patients with pleural mesothelioma, and can give symptomatic benefits. This combination has become the standard of care in mesothelioma treatment.

Antineoplastic Agents↗
PubMed2003

Mesothelin-family proteins and diagnosis of mesothelioma.

BACKGROUND: Mesothelioma is a highly aggressive tumour for which there are no reliable serum tumour markers. Identification of such a marker would be useful in diagnosis of mesothelioma and for monitoring responses to treatment and screening at-risk individuals. METHODS: We assayed serum concentrations of soluble mesothelin-related proteins (SMR) using a double determinant (sandwich) ELISA in a blinded study of serum samples from 44 patients with histologically proven mesothelioma; 68 matched healthy controls, 40 of whom had been exposed to asbestos; and 160 patients with other inflammatory or malignant lung and pleural diseases. FINDINGS: 37 (84%) of 44 patients with mesothelioma had raised concentrations of SMR at a serum dilution of 1/80, compared with three (2%) of 160 patients with other cancers or other inflammatory lung or pleural diseases, and with none of 28 controls who had not been exposed to asbestos. SMR concentrations correlated with tumour size and increased during tumour progression. Seven of the 40 asbestos-exposed individuals had increased serum concentrations of SMR; three of those seven developed mesothelioma and one developed lung carcinoma within 1-5 years. None of the 33 asbestos-exposed participants whose serum samples had normal concentrations of SMR and who were followed up over 8 years developed mesothelioma. INTERPRETATION: Determination of SMR in serum could be a useful marker for diagnosis of mesothelioma and to monitor disease progression. It might also prove helpful for screening asbestos-exposed individuals for early evidence of mesothelioma.

Antigens, Neoplasm↗
PubMed2003

IL-2 intratumoral immunotherapy enhances CD8+ T cells that mediate destruction of tumor cells and tumor-associated vasculature: a novel mechanism for IL-2.

Therapeutic use of IL-2 can generate antitumor immunity; however, a variety of different mechanisms have been reported. We injected IL-2 intratumorally (i.t.) at different stages of growth, using our unique murine model of mesothelioma (AE17; and AE17 transfected with secretory OVA (AE17-sOVA)), and systematically analyzed real-time events as they occurred in vivo. The majority of mice with small tumors when treatment commenced displayed complete tumor regression, remained tumor free for >2 mo, and survived rechallenge with AE17 tumor cells. However, mice with large tumors at the start of treatment failed to respond. Timing experiments showed that IL-2-mediated responses were dependent upon tumor size, not on the duration of disease. Although i.t. IL-2 did not alter tumor Ag presentation in draining lymph nodes, it did enhance a previously primed, endogenous, tumor-specific in vivo CTL response that coincided with regressing tumors. Both CD4(+) and CD8(+) cells were required for IL-2-mediated tumor eradication, because IL-2 therapy failed in CD4(+)-depleted, CD8(+)-depleted, and both CD4(+)- and CD8(+)-depleted C57BL/6J animals. Tumor-infiltrating CD8(+) T cells, but not CD4(+) T cells, increased in association with a marked reduction in tumor-associated vascularity. Destruction of blood vessels required CD8(+) T cells, because this did not occur in nude mice or in CD8(+)-depleted C57BL/6J mice. These results show that repeated doses of i.t. (but not systemic) IL-2 mediates tumor regression via an enhanced endogenous tumor-specific CTL response concomitant with reduced vasculature, thereby demonstrating a novel mechanism for IL-2 activity.

Adjuvants, Immunologic↗
PubMed2003

Synergy between chemotherapy and immunotherapy in the treatment of established murine solid tumors.

Cytotoxic chemotherapy is generally considered immunosuppressive, with neutropenia and lymphopenia being common adverse side effects. In this context, we have shown previously that the cytidine analogue, gemcitabine, abolishes humoral responses but, in contrast, augments antigen-specific cellular antitumor immunity. This augmentation occurs in the context of increased antigen cross-presentation, T lymphocyte expansion, and infiltration of the tumor. Here, we combine an immunotherapy (CD40 ligation using FGK45; 100 micro g; i.p., q2dx3) with gemcitabine (120 microg/gram; i.p.; q3dx5) to treat established solid tumors. This protocol induced long-term cures in < or =80% of mice, and all of the cured mice were resistant to tumor rechallenge. Synergy between the drug and immunotherapy could not be established in vitro and was only seen in the context of tumor cell death. It was associated with an increase in both CD4 and CD8 T-cell infiltration of the tumor, but depletion studies clearly showed that CD4 T cells were not a necessary component of the cure. In contrast, CD8 T cells were absolutely required for the success of this treatment regimen. The priming effect of gemcitabine was not limited to debulking, because mice resected to an equivalent, or lesser residual tumor volume did not eradicate tumor with subsequent immunotherapy. This study provides evidence that chemotherapy has the capacity to augment cellular antitumor immunity, a finding with wider implications for the management of treatment-resistant solid tumors.

Animals↗