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Adrian L Harris

Publications and source records attributed to Adrian L Harris.

At least 91 records · Page 5Linked to original sources
PubMed2004

Non-linear survival analysis using neural networks.

We describe models for survival analysis which are based on a multi-layer perceptron, a type of neural network. These relax the assumptions of the traditional regression models, while including them as particular cases. They allow non-linear predictors to be fitted implicitly and the effect of the covariates to vary over time. The flexibility is included in the model only when it is beneficial, as judged by cross-validation. Such models can be used to guide a search for extra regressors, by comparing their predictive accuracy with that of linear models. Most also allow the estimation of the hazard function, of which a great variety can be modelled. In this paper we describe seven different neural network survival models and illustrate their use by comparing their performance in predicting the time to relapse for breast cancer patients.

Breast Neoplasms↗
PubMed2004

The hypoxia-regulated transcription factor DEC1 (Stra13, SHARP-2) and its expression in human tissues and tumours.

DEC1, also known as SHARP-2 or Stra13, is an important molecule in embryonic differentiation and has recently been identified to be strongly inducible by hypoxia. Its distribution in normal human tissues and most tumour types is unknown. In the present study, a polyclonal antiserum to a 10-amino acid peptide from DEC1 has been raised. Using this antiserum, DEC1 was shown to be widely expressed in most normal human tissues, but usually only in a proportion of cells and typically with a nuclear localization. In tumours, expression was either augmented (the commonest pattern) or occasionally decreased. Similarly, in most normal tissues, low or absent expression was observed in endothelial cells, whereas in many tumour samples endothelium was usually strongly positive. In tumours, there was a striking pattern of staining seen in connection with areas of necrosis, with absence of DEC1 expression within a zone of morphologically viable cells immediately adjacent to the necrotic zone. This suggests that while DEC1 may be up-regulated by hypoxia in cancer, in more extreme hypoxia it may have a role in cell death. Its interrelationship with other hypoxically regulated molecules, such as the hypoxia-inducible factors or carbonic anhydrase IX, and differentiation of tumours now requires further investigation.

Animals↗
PubMed2004

Hypoxia-inducible factors and hypoxic cell death in tumour physiology.

Hypoxic up-regulation of hypoxia-inducible factors (HIFs) during tumourigenesis presents an interesting paradox with respect to their role in tumour growth. Hypoxia-inducible factor 1 (HIF-1) plays a key role in the adaptive response to hypoxia, trans-activating many genes whose protein products are involved in pathways of angiogenesis, glucose metabolism and cell proliferation, thus facilitating tumour progression. However, it is also emerging that up-regulation of HIF-1 trans-activates anti-proliferative and pro-apoptotic genes (such as BNIP3, NIX and IGFBP3). This makes it unclear as to whether HIF-1 up-regulation provides a selective advantage or disadvantage to neoplastic progression under hypoxia. In addition, vagaries in the hypoxic microenvironment of the tumour such as pH changes, presence of reactive oxygen species and energy availability in the form of adenosine triphosphate (ATP), appear to influence the function of HIF-1 and up-regulated pathways and affect susceptibility to undergo hypoxic cell death. It is apparent that hypoxic cancer cells must be able to select against HIF-1 mediated cell death signals in order to survive and progress towards malignancy. Hypoxia-induced HIF-1 may in itself serve to select for increased malignancy by exerting pressure in the form of anti-proliferative signals that must be escaped. Understanding the mechanisms by which HIF-1 induces cell death and the manner in which the tumour cell can overcome such signals, is critical for our understanding of cancer progression and the development of effective therapeutics.

Animals↗
PubMed2004

Novel angiogenic signaling pathways and vascular targets.

Intense investigation into the molecular basis of angiogenesis is rapidly revealing novel signaling pathways involved in the generation of new vasculature. These range from elucidation of the mechanism by which hypoxia initiates expression of a proangiogenic gene repertoire via the hypoxia-inducible transcription factors (HIFs) to molecular pathways involved in extra- and intracellular signaling during new vessel formation. Extracellular pathways include those of the Notch/delta, ephrin/Eph receptor and roundabout/slit families, and intracellular pathway members of the hedgehog and sprouty families. The involvement of these pathways in angiogenesis is discussed, together with some comments on recently identified targets in the vasculature that present new therapeutic opportunities.

Animals↗
PubMed2004

Utilizing the adjuvant properties of CD1d-dependent NK T cells in T cell-mediated immunotherapy.

Activation of invariant CD1d-dependent NK T cells (iNKT cells) in vivo through administration of the glycolipid ligand alpha-galactosylceramide (alpha-GalCer) or the sphingosine-truncated alpha-GalCer analog OCH leads to CD40 signaling as well as the release of soluble molecules including type 1 and gamma interferons that contribute to DC maturation. This process enhances T cell immunity to antigens presented by the DC. The adjuvant activity is further amplified if APCs are stimulated through Toll-like receptor 4, suggesting that iNKT cell signals can amplify maturation induced by microbial stimuli. The adjuvant activity of alpha-GalCer enhances both priming and boosting of CD8(+) T cells to coadministered peptide or protein antigens, including a peptide encoding the clinically relevant, HLA-A2-restricted epitope of the human tumor antigen NY-ESO-1. Importantly, alpha-GalCer was used to induce CD8(+) T cells to antigens delivered orally, despite the fact that this route of administration is normally associated with blunted responses. Only T cell responses induced in the presence of iNKT cell stimulation, whether by the i.v. or oral route, were capable of eradicating established tumors. Together these data highlight the therapeutic potential of iNKT cell ligands in vaccination strategies, particularly "heterologous prime-boost" strategies against tumors, and provide evidence that iNKT cell stimulation may be exploited in the development of oral vaccines.

Animals↗
PubMed2004

Hypoxia inducible carbonic anhydrase IX, marker of tumour hypoxia, survival pathway and therapy target.

Over 50 genes are inducible by hypoxia, via hypoxia inducible factor 1alpha (HIF-1alpha). Carbonic anhydrase IX (CAIX) is one of the most inducible and most uniformly induced genes and because of its stability and membrane location provides a reliable histochemical marker of hypoxia. Recent studies have shown the importance of pH in cell death under hypoxia, thus mechanisms of pH regulation are likely to be vital pathways for survival. Carbonic anhydrases have a widespread role in normal tissues in regulating pH, with 14 isoforms described, so inhibition may have substantial normal tissue toxicity. Selective nonmembrane permeable inhibitors are available and may synergise with chemotherapy agents more active in acid conditions. CAIX has a major role in regulating hydrogen ion (H+) flux and blockade of CAIX results in increased cell death under hypoxia, indicating that it is one mechanism of hypoxic adaptation. As it is commonly expressed in tumours with the worst prognosis it is a potential target for therapy.

Animals↗
PubMed2004

Macrophage infiltration and angiogenesis in human malignancy.

It is well recognized that human tumours are hypoxic compared to normal adjacent tissues and that hypoxia is related to a poor outcome regardless of modality of treatment, including surgery alone, radiotherapy or chemotherapy. Hypoxia regulates a complex programme of gene transcription via hypoxia-inducible factors 1 and 2 (HIF-1, -2). We have shown that in breast cancer and many other tumour types, tumour-associated macrophages express high levels of HIF-2alpha compared to normal tissue macrophages and compared to the tumour. This high macrophage HIF-2alpha is an independent prognostic factor for poor outcome. The mechanisms up-regulating HLF-2alpha in macrophages may include inflammatory cytokines as well as hypoxia. Differentiation of monocytes into macrophages increases the basal level of HIF-2alpha protein and changes the programme of hypoxia. Many of these inducible genes are involved in inflammation and angiogenesis. Thus, the conversion of a peripheral monocyte into a macrophage generates a complex new programme of hypoxia-responsive genes that may contribute to angiogenesis and the complex microenvironment within the tumour, and as such provides important targets for therapy.

Animals↗
PubMed2003

Synergistic effect of metronomic dosing of cyclophosphamide combined with specific antitumor immunotherapy in a murine melanoma model.

Immunotherapy could be combined with conventional chemotherapeutic modalities aimed at reducing tumor burden. Such combination therapy may be most useful when "metronomic" doses of antineoplastic drugs are used, thereby potentially avoiding some of the immunosuppressive effects of these drugs. Recent studies have shown that some conventional antineoplastic drugs can be exploited for antiangiogenic capacities, a strategy that requires drugs to be administered at regular intervals. We therefore investigated whether such metronomic therapy with the alkylating agent cyclophosphamide (CTX) could be effectively combined with immunotherapy eliciting tumor-reactive CTLs. An immunization protocol using injection of recombinant DNA followed by injection of recombinant modified vaccinia virus Ankara strain was used to initiate a specific CTL response in mice capable of providing resistance to challenge with the murine melanoma B16.F10. Combining this immunotherapeutic regime with metronomic delivery of CTX resulted in antitumor activity that was dramatically enhanced over either treatment administered alone and was also significantly greater than combining immunotherapy with CTX administered by a maximum tolerated dose regime. Whereas both metronomic and maximum tolerated dose delivery of CTX did cause deletion of proliferating tumor-specific CTLs in the blood, this deletion occurred with slower kinetics with the metronomic schedule. Further analysis showed that metronomic CTX treatment did not delete cells with low expression of CD43, a "memory" phenotype, and that these cells maintained potent restimulatory capacity. The combination of immunotherapy and metronomic CTX therapy may be well suited to clinical management of cancer.

Animals↗
PubMed2003

The cardiovascular safety of high-dose intravenous granisetron in cancer patients receiving highly emetogenic chemotherapy.

OBJECTIVES: To assess the cardiovascular safety, tolerability and efficacy of high doses of granisetron for the treatment of nausea and vomiting in patients undergoing highly emetogenic chemotherapy. METHODS: Patients with histologically confirmed malignant disease were given an intravenous infusion of granisetron, 160 microg/kg, over 30 min, starting 15 min after highly emetogenic chemotherapy. Patients underwent cardiac monitoring for 24 h following the granisetron infusion. Pulse, blood pressure and electrocardiogram (lead II and ambulatory) measurements were taken, and routine clinical chemistry and haematology tests performed. Blood samples for pharmacokinetic analysis were taken before the granisetron infusion, and at intervals afterwards. Adverse events were self-assessed using a symptom checklist. Self-assessment categorical rating scales were used to evaluate patient nausea, vomiting and retching. RESULTS: Ten patients (eight females and two males; average age 41.5 years) completed the trial and were included in the safety and efficacy assessments. No clinically relevant changes in electrocardiogram, pulse rate, blood pressure or laboratory parameters were observed. Furthermore, in the 7 days following dosing there were no serious adverse events leading to withdrawal from the trial. A complete response (no vomiting, retching or, at most, mild nausea) was experienced by five patients. Six patients had no, or mild, nausea and an additional two patients vomited on a maximum of two occasions. Additional antiemetic rescue medication was given to three patients during the 24-h trial period. Despite considerable interpatient variability, C(max) and AUC parameters were proportionally greater than values reported for lower doses of granisetron. CONCLUSIONS: Granisetron administered at four times the upper recommended dose demonstrated good efficacy and tolerability with no clinically important cardiac effects.

Adult↗
PubMed2003

NKT cells enhance CD4+ and CD8+ T cell responses to soluble antigen in vivo through direct interaction with dendritic cells.

Modification in the function of dendritic cells (DC), such as that achieved by microbial stimuli or T cell help, plays a critical role in determining the quality and size of adaptive responses to Ag. NKT cells bearing an invariant TCR (iNKT cells) restricted by nonpolymorphic CD1d molecules may constitute a readily available source of help for DC. We therefore examined T cell responses to i.v. injection of soluble Ag in the presence or the absence of iNKT cell stimulation with the CD1d-binding glycolipid alpha-galactosylceramide (alpha-GalCer). Considerably enhanced CD4(+) and CD8(+) T cell responses were observed when alpha-GalCer was administered at the same time as or close to OVA injection. This enhancement was dependent on the involvement of iNKT cells and CD1d molecules and required CD40 signaling. Studies in IFN-gammaR(-/-) mice indicated that IFN-gamma was not required for the adjuvant effect of alpha-GalCer. Consistent with this result, enhanced T cell responses were observed using OCH, an analog of alpha-GalCer with a truncated sphingosine chain and a reduced capacity to induce IFN-gamma. Splenic DC from alpha-GalCer-treated animals expressed high levels of costimulatory molecules, suggesting maturation in response to iNKT cell activation. Furthermore, studies with cultured DC indicated that potentiation of T cell responses required presentation of specific peptide and alpha-GalCer by the same DC, implying conditioning of DC by iNKT cells. The iNKT-enhanced T cell responses resisted challenge with OVA-expressing tumors, whereas responses induced in the absence of iNKT stimulation did not. Thus, iNKT cells exert a significant influence on the efficacy of immune responses to soluble Ag by modulating DC function.

Adjuvants, Immunologic↗
PubMed2003

Anoxic induction of ATF-4 through HIF-1-independent pathways of protein stabilization in human cancer cells.

Hypoxia is a key factor in tumor development, contributing to angiogenesis and radiotherapy resistance. Hypoxia-inducible factor-1 (HIF-1) is a major transcription factor regulating the response of cancer cells to hypoxia. However, tumors also contain areas of more severe oxygen depletion, or anoxia. Mechanisms for survival under anoxia are HIF-1alpha independent in Caenorhabditis elegans and, thus, differ from the hypoxic response. Here we report a differential response of cancer cells to hypoxia and anoxia by demonstrating the induction of activating transcription factor-4 (ATF-4) and growth arrest DNA damage 153 (GADD153) protein specifically in anoxia and the lack of induction in hypoxia. By applying RNAi, ATF-4 induction in anoxia was shown to be independent of HIF-1alpha, and desferrioxamine mesylate (DFO) and cobalt chloride induced HIF-1alpha but not ATF-4 or GADD153. Furthermore, the inductive response of ATF-4 and GADD153 was not related to alterations in or arrest of mitochondrial respiration and was independent of von Hippel-Lindau (VHL) disease mutations. In reoxygenated anoxic cells, ATF-4 had a half-life of less than 5 minutes; adding the proteasome inhibitor to normoxic cells up-regulated ATF-4 protein. Extracts from primary human tumors demonstrated more ATF-4 expression in tumors near necrotic areas. Thus, this study demonstrates a novel HIF-1alpha-independent anoxic mechanism that regulates ATF-4 induction at the protein stability level in tumor cells.

Activating Transcription Factor 4↗
PubMed2003

Amifostine induces anaerobic metabolism and hypoxia-inducible factor 1 alpha.

PURPOSE: The cytoprotective mechanism of amifostine (WR-2721) implies free radical scavenging and DNA repair activities. We investigated additional cytoprotective pathways involving intracellular hypoxia and the activation of the hypoxia-inducible factor (HIF) pathway, a key transcription factor regulating glycolysis, angiogenesis and apoptosis, which is also linked with radioresistance. MATERIALS AND METHODS: The glucose and oxygen levels in the peripheral blood of patients receiving 1000 mg amifostine were determined at various time-points in order to investigate the metabolic changes induced by amifostine. MDA468 breast tumor cell lines were incubated with a high amifostine concentration (10 m M) to overcome the natural resistance of cancer cells to influx of the non-hydrolyzed WR-2721, and the HIF1 alpha protein levels were determined by Western blot analysis. In vivo experiments with Wistar rats were performed in order to assess immunohistochemically changes in the intracellular accumulation of HIF1 alpha induced by amifostine (200 mg/kg). RESULTS: By 30 min following amifostine administration, the hemoglobin oxygen saturation and pO(2) levels had increased in the peripheral blood while glucose levels had reduced, providing evidence that normal tissue metabolism switches to glycolytic pathways. Incubation of cell lines with amifostine resulted in HIF1 alpha induction. In Wistar rats administration of amifostine resulted in increased HIF1 alpha accumulation in normal tissues. CONCLUSIONS: Since it is doubtful whether dephosphorylation of amifostine to the active metabolite WR-1065 occurs within tumoral tissues (an acidic environment that lacks vascular alkaline phosphatase activity), intracellular hypoxia and upregulation of HIF1 alpha represents an additional, normal tissue-specific, amifostine cytoprotective pathway.

Amifostine↗
PubMed2003

Pharmacokinetic study of cisplatin and infusional etoposide phosphate in advanced breast cancer with correlation of response to topoisomerase IIalpha expression.

PURPOSE: There is substantial interpatient variability in etoposide pharmacokinetics. Pharmacokinetic adjustment to specific plasma concentrations may make it possible to define a therapeutic plasma concentration and relate drug target expression in the tumor to response. This study evaluated the combination of cisplatin with a prolonged infusion of etoposide phosphate (EP) in advanced breast cancer and correlated response to topoisomerase II expression. EXPERIMENTAL DESIGN: Eligible patients, previously treated with an anthracycline, received 60 mg/m(2) cisplatin, followed by a 5-day infusion of EP. Plasma etoposide levels were measured on days 2 and 4 of each cycle with adjustment of the infusion rate to achieve an initial target etoposide concentration of 2 micro g/ml or 1.5 micro g/ml. Primary tumor blocks were stained by immunohistochemistry for topoisomerase IIalpha and beta. RESULTS: Thirty-six patients, treated in three consecutive cohorts, received 145 cycles of chemotherapy. Targeting plasma etoposide concentration reduced interpatient pharmacokinetic variability (32% and 62% of patients, respectively, within 10% of target concentration on days 2 and 4; cycle 1). Significant hematological toxicity (89% of patients with at least one episode of grade III/IV neutropenia, 64% of patients with at least one episode of grade III/IV thrombocytopenia) was observed. Thirty-nine percent of patients achieved a partial response, and 19% had stable disease for at least 3 months. The median time to tumor progression was 4 months, with a median survival of 11 months. Topoisomerase IIalpha expression was significantly higher (P < 0.001) in responding patients compared with those with stable or progressive disease. There was no difference in topoisomerase IIbeta expression between groups. CONCLUSION: Cisplatin and infusional EP is an active, but intensive, schedule in heavily pretreated patients with breast cancer. Clinical response correlates with tumor topoisomerase IIalpha expression.

Adult↗
PubMed2003

Cytoplasmic p21WAF1/CIP1 expression is correlated with HER-2/ neu in breast cancer and is an independent predictor of prognosis.

BACKGROUND: HER-2 (c-erbB2/Neu) predicts the prognosis of and may influence treatment responses in breast cancer. HER-2 activity induces the cytoplasmic location of p21WAFI/CIPI in cell culture, accompanied by resistance to apoptosis. p21WAFI/CIPI is a cyclin-dependent kinase inhibitor activated by p53 to produce cell cycle arrest in association with nuclear localisation of p21WAFI/CIPI. We previously showed that higher levels of cytoplasmic p21WAFI/CIPI in breast cancers predicted reduced survival at 5 years. The present study examined HER-2 and p21WAFI/CIPI expression in a series of breast cancers with up to 9 years of follow-up, to evaluate whether in vitro findings were related to clinical data and the effect on outcome. METHODS: The CB11 anti-HER2 monoclonal antibody and the DAKO Envision Plus system were used to evaluate HER-2 expression in 73 patients. p21WAFI/CIPI staining was performed as described previously using the mouse monoclonal antibody Ab-1 (Calbiochem, Cambridge, MA, USA). RESULTS: HER-2 was evaluable in 67 patients and was expressed in 19% of cases, predicting reduced overall survival (P = 0.02) and reduced relapse-free survival (P = 0.004; Cox regression model). HER-2-positive tumours showed proportionately higher cytoplasmic p21WAFI/CIPI staining using an intensity distribution score (median, 95) compared with HER-2-negative cancers (median, 47) (P = 0.005). There was a much weaker association between nuclear p21WAFI/CIPI and HER-2 expression (P = 0.05), suggesting an inverse relationship between nuclear p21WAF1/CIP1 and HER-2. CONCLUSION: This study highlights a new pathway by which HER-2 may modify cancer behaviour. HER-2 as a predictor of poor prognosis may partly relate to its ability to influence the relocalisation of p21WAFI/CIPI from the nucleus to the cytoplasm, resulting in a loss of p21WAFI/CIPItumour suppressor functions. Cytoplasmic p21WAFI/CIPI may be a surrogate marker of functional HER-2 in vivo.

Adult↗
PubMed2003

The relationship of human wound vascular endothelial growth factor (VEGF) after breast cancer surgery to circulating VEGF and angiogenesis.

PURPOSE: The assessment of locally produced proangiogenic cytokines may be an indicator of the stromal response of an individual to wounding or cancer. This study describes the profile of VEGF production in human surgical wounds in both breast cancer patients and reduction mammoplasty controls, and assesses the changes in systemic VEGF levels and platelet profiles perioperatively. EXPERIMENTAL DESIGN: Perioperative surgical wound fluid samples and blood were collected daily up to 13 days from 52 patients undergoing breast cancer surgery (local tumor burden), delayed breast reconstruction (previous tumor burden but none present at the time of surgery), or breast reduction surgery (noncancer control). Samples were analyzed for VEGF by ELISA RESULTS: VEGF levels in surgical wound fluid were lowest on day 1 followed by an early peak on day 2 of >900% the corresponding serum value. There was a trend in the VEGF response at the day-2 time point: reduction > reconstruction > cancer subgroups, with a significant difference between the reduction and cancer subgroups (P < 0.05). There was a 20-30-fold variation in the response between days 1 and 2, and within subgroups. CONCLUSIONS: Much higher local concentrations of angiogenic factors may need to be antagonized for effective antiangiogenic therapy, and there is great heterogeneity between patients. The small peripheral blood changes compared with large tumor fluid changes show that there is a tissue barrier. This has relevance for design of antiangiogenic therapy trials, highlighting the need for individually tailored treatment with biologically targeted interventions.

Adolescent↗
PubMed2003

Predominant role of hypoxia-inducible transcription factor (Hif)-1alpha versus Hif-2alpha in regulation of the transcriptional response to hypoxia.

Tumor hypoxia induces the up-regulation of a gene program associated with angiogenesis, glycolysis, adaptation to pH, and apoptosis via the hypoxia-inducible transcription factors (Hifs) 1 and 2. Disruption of this pathway has been proposed as a cancer therapy. Here, we use short interfering RNAs to compare specific inactivation of Hif-1alpha or Hif-2alpha and show markedly different cell type-specific effects on gene expression and cell migration. Remarkably, among a panel of hypoxia-inducible genes, responses were critically dependent on Hif-1 alpha but not Hif-2 alpha in both endothelial and breast cancer cells but critically dependent on Hif-2 alpha in renal carcinoma cells.

Basic Helix-Loop-Helix Proteins↗
PubMed2003

Enhanced expression of SPARC/osteonectin in the tumor-associated stroma of non-small cell lung cancer is correlated with markers of hypoxia/acidity and with poor prognosis of patients.

Secreted Protein Acidic and Rich in Cystein (SPARC)/osteonectin is a nonstructural matricellular protein involved in cell-matrix interaction during tissue remodeling and embryonic development. Using a novel monoclonal antibody (10-255), we examined immunohistochemically the patterns of SPARC expression in non-small cell lung cancer (NSCLC). High levels of SPARC in normal lung were confined exclusively to the bronchial cartilage. In NSCLC tissues, cancer cells were unreactive in 107 of 113 cases analyzed (95%), whereas substantial production of SPARC by stromal fibroblasts was noted in 42 of 113 cases (37%). Stromal SPARC was linked with tumor necrosis (P = 0.01) and, marginally, with node metastasis (P = 0.07), as well as with high levels of carbonic anhydrase 9 and LDH in cancer cells (P = 0.0001 and P = 0.01, respectively). SPARC was also coincident with enhanced levels of cancer cell differentiated embryo-chondrocyte expressed gene 1, hypoxia inducible factor 2alpha, and thymidine phosphorylase (P = 0.01, P = 0.05, and P = 0.03, respectively). Although endothelial reactivity for SPARC was noted only in small, immature vessels, SPARC production by stroma cells supported a high degree of vascular maturation (indicated by the presence of subendothelial lamina lucida). Survival analysis revealed a significant association of stromal SPARC with poor prognosis (P = 0.006), a finding that was also confirmed in multivariate models. In NSCLC, SPARC is selectively synthesized by the cells of the tumoral stroma. The strong association of this feature with markers of intratumoral hypoxia and acidity indicates an interesting link between cancer cell metabolism and the induction of a supportive stroma that favors cancer cell invasion and migration that lead to an ominous clinical outcome.

Adenocarcinoma↗