An investigation of the clinical impact and therapeutic relevance of a DNA damage immune response (DDIR) signature in patients with advanced gastroesophageal adenocarcinoma

BACKGROUND

An improved understanding of which gastroesophageal adenocarcinoma (GOA) patients respond to both chemotherapy and immune checkpoint inhibitors (ICI) is needed. We investigated the predictive role and underlying biology of a 44-gene DNA damage immune response (DDIR) signature in patients with advanced GOA.

MATERIALS AND METHODS

Transcriptional profiling was carried out on pretreatment tissue from 252 GOA patients treated with platinum-based chemotherapy (three dose levels) within the randomized phase III GO2 trial. Cross-validation was carried out in two independent GOA cohorts with transcriptional profiling, immune cell immunohistochemistry and epidermal growth factor receptor (EGFR) fluorescent in situ hybridization (FISH) (n = 430).

RESULTS

In the GO2 trial, DDIR-positive tumours had a greater radiological response (51.7% versus 28.5%, P = 0.022) and improved overall survival in a dose-dependent manner (P = 0.028). DDIR positivity was associated with a pretreatment inflamed tumour microenvironment (TME) and increased expression of biomarkers associated with ICI response such as CD274 (programmed death-ligand 1, PD-L1) and a microsatellite instability RNA signature. Consensus pathway analysis identified EGFR as a potential key determinant of the DDIR signature. EGFR amplification was associated with DDIR negativity and an immune cold TME.

CONCLUSIONS

Our results indicate the importance of the GOA TME in chemotherapy response, its relationship to DNA damage repair and EGFR as a targetable driver of an immune cold TME. Chemotherapy-sensitive inflamed GOAs could benefit from ICI delivered in combination with standard chemotherapy. Combining EGFR inhibitors and ICIs warrants further investigation in patients with EGFR-amplified tumours.

Fission chamber data acquisition system for neutron flux measurements on the Mega-Amp Spherical Tokamak Upgrade

Neutron flux measurements are important in fusion devices for both safety requirements and physics studies. A new system has been built for the Mega-Amp Spherical Tokamak Upgrade (MAST Upgrade) that provides neutron count, DC, and Campbell mode measurements for a 1 µs period at 1 MHz. The acquisition system uses a Red Pitaya board to sample current from two fission chambers mounted on the side of the MAST-U vessel. The system-on-chip design of the Zynq-7020 on the Red Pitaya also allows a web server implementation using Flask for data retrieval and diagnostic configuration over the MAST Upgrade network.

OTHR-03. Oxaliplatin as a hearing-sparing alternative to carboplatin in tandem autologous stem cell transplants in pediatric CNS malignancy

BACKGROUND: Intensive chemotherapy with tandem autologous stem cell transplants (autoSCT) is shown to improve survival for children with CNS malignancy. Platinum-based chemotherapeutic agents in these regimens, mainly cisplatin and carboplatin, have resulted in significant sensorineural hearing loss. Oxaliplatin, a newer platinum-based agent, is considered less ototoxic. Empiric substitution of oxaliplatin for carboplatin in preparative regimens for autoSCT have been tried. However, the survival and ototoxicity outcomes have not been studied. OBJECTIVE: To compare the overall survival and ototoxicity of oxaliplatin versus carboplatin preparatory chemotherapy regimens in children who received tandem autoSCT for treatment of CNS malignancy. METHODS: We performed a retrospective chart review of all pediatric patients with primary CNS tumors who received tandem autoSCT from 2011 to 2018 at Children’s Hospital Colorado. Demographics, clinical outcomes, and medication administration records were extracted from electronic medical records. Hearing evaluations, performed at pre-transplant, after each transplant episode, and at follow-up visits, were reviewed and graded by an audiologist. Comparisons were performed using Fisher’s exact tests and log rank test statistics. RESULTS: 32 pediatric patients with CNS tumors met inclusion criteria. Seven patients received oxaliplatin in place of carboplatin in one or more preparatory regimens. There was no statistically significant difference in overall survival between the two groups (p=0.99). A total of 85 follow-up audiograms were available for assessment, including long-term follow up. Of the 13 audiograms that showed hearing loss, one (8%) had prior oxaliplatin exposure, compared to 18/72 (25%) audiograms without hearing loss had prior oxaliplatin exposure (p=0.28). CONCLUSIONS: Oxaliplatin is effective and well-tolerated when used in lieu of carboplatin in preparatory regimen for autoSCT for pediatric CNS malignancy. This study is limited by its small size. A larger, multi-center study is warranted to confirm oxaliplatin’s safety and effect on survival and ototoxicity in pediatric autoHSCT.

Do European patients with peripeheral arterial disease receive optimal lipid lowering therapy and achieve LDL-C goals? Results from the DA VINCI study

Background

2016 and 2019 EAS/ESC dyslipidemia guidelines recommend lipid lowering therapy (LLT) to reduce LDL-C in patients with peripheral arterial disease (PAD) with or without established cardiovascular (CV) disease, and recommend target LDL-C goals based on individual CV risk. Data regarding the implementation of these guidelines in clinical practice across Europe is currently lacking.

Purpose

Describe LLT and achievement of the target LDL-C goals recommended in EAS/ESC dyslipidemia guidelines in patients with PAD.

Methods

The cross-sectional Da Vinci study enrolled consenting adults who had received LLT in the 12 months prior to the study visit and had at least one LDL-C measurement in the 14 months prior to the study visit, seen in a primary or secondary care setting across 18 European countries. Patients with coronary, peripheral and cerebral disease were enrolled at a ratio of 1:2:2. FH patients with prior CV events were excluded. Data were collected from medical records at a single visit between Jun '17–Nov '18, including LLT and most recent LDL-C. Primary outcome was LDL-C goal attainment ≥28 days after starting most recent LLT (treatment-stabilised LLT).

Results

Of 5888 patients enrolled, 2794 met our definition of atherosclerotic cardiovascular disease (ASCVD). Of these ASCVD patients, 1036 (37%) had PAD. 31% (323/1036) of PAD patients were female and mean (SD) age was 69 (9.4) years. Concomitant CV risk factors included diabetes mellitus (473/1036 patients [46%]), hypertension (809/1036 [78%]) and smoking (794/1036 [77%]). 26% (271/1036) of patients with PAD also had coronary vascular disease and 12% (122/1036) also had cerebrovascular disease. At the visit date, approximately half (497/1036 [48%]) of all PAD patients were receiving moderate intensity statins and 41% (421/1036) were receiving high intensity statins. 818 (73%) of the PAD patients had a treatment-stabilised LDL-C measurement (median, 2.20 mmol/L), of whom 40% (326/818) achieved the 2016 EAS/ESC LDL-C goal of 1.8 mmol/L and only 19% (159/818) achieved the 2019 goal of 1.4mmol/L.

Conclusions

European patients with PAD are not treated as per EAS/ESC recommendations, with a large proportion receiving suboptimal LLT and fewer than half achieving target LDL-C levels.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Amgen

What is the potential cardiovascular risk reduction associated with achieving LDL-C levels recommended in the ESC/EAS guidelines for very high-risk patients? Data from 18 European countries

Background/Introduction

For patients at very-high risk of cardiovascular (CV) events, the 2016 ESC/EAS dyslipidaemia guidelines recommended lipid-lowering therapy (LLT) to achieve an LDL-C level below 70 mg/dL. This was lowered to an LDL-C level below 55 mg/dL in the 2019 guidelines.

Purpose

To assess: 1) the risk profile of European patients with established atherosclerotic CV disease (ASCVD) receiving LLT; and 2) the treatment gap between the estimated risk and the population benefits if all patients were to achieve LDL-C levels of 70 mg/dL and 55 mg/dL.

Methods

We used data from Da Vinci, an observational cross-sectional study conducted across 18 European countries. Data were collected at a single visit between June 2017 and November 2018, for consented adults who had received any LLT in the prior 12 months and had an LDL-C measurement in the prior 14 months. LDL-C level was assessed at least 28 days after starting the most recent LLT (stabilised LLT). For each patient with established ASCVD receiving stabilised LLT, we: 1) calculated their absolute LDL-C reduction required to achieve LDL-C levels of 70 mg/dL and 55 mg/dL; 2) predicted their 10-year CV risk using the REACH score based on demographic and medical history; 3) simulated their relative risk reduction (RRR) by randomly sampling from the probability distribution of the rate ratio per 38.7 mg/dL (1 mmol/L) estimated by the Cholesterol Treatment Trialists Collaboration meta-analysis; and 4) calculated their absolute risk reduction (ARR) achieved by meeting LDL-C levels of 70 mg/dL and 55 mg/dL.

Results

A total of 2039 patients with established ASCVD were included in the analysis. Mean (SD) LDL-C was 83.1 (35.2) mg/dL. 40.4% and 19.3% of patients achieved LDL-C levels of 70 mg/dL and 55 mg/dL, respectively. Mean (SD) 10-year CV risk calculated using the REACH score was 36.3% (15.4%). Mean absolute LDL-C reductions of 19.6 mg/dL and 30.4 mg/dL were needed to reach LDL-C levels of 70 mg/dL and 55 mg/dL, respectively. When adjusted for the LDL-C reduction required to achieve an LDL-C level of 70 mg/dL, mean ARR was 3.0%, leaving a mean (SD) residual 10-year CV risk of 33.3% (15.5%). When adjusted for the LDL-C reduction required to achieve an LDL-C level of 55 mg/dL, mean ARR was 4.6%, leaving a mean (SD) residual 10-year CV risk of 31.7% (15.2%).

Conclusion(s)

In a contemporary European cohort with ASCVD receiving LLT, the 10-year risk of CV events is high and many patients do not achieve LDL-C levels of 55 mg/dL or even of 70 mg/dL. Moreover, even if all patients were to achieve recommended LDL-C levels, they would still remain at a high residual risk of CV events. These data suggest these patients require even more intensive LLT.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Amgen

Recovery of an urbanised estuary: Clean-up, de-industrialisation and restoration of redundant dock-basins in the Mersey

For much of the 20th century, the Mersey in North West England was one of the worst polluted estuaries in Europe. Water from a range of polluting industries plus domestic sewage was discharged into the Mersey Catchment and Estuary. Recovery came through a concerted clean-up campaign and tightening environmental regulations, partly driven by European Commission Directives, coupled with de-industrialisation from the 1970s onward. Recovery of oxygen levels in the Estuary led to the return of a productive ecosystem. This led to conservation designations, but also concerns about transfer of pollutants to higher trophic levels in fish, birds and humans. As part of urban renewal, ecosystems in disused dock basins were restored using mussel biofiltration and artificial de-stratification, facilitating commercial redevelopment and creation of a tourist destination. The degradation and recovery of the Mersey from peak-pollution in the mid-20th century is put in the context of wider environmental change and briefly compared to other systems to develop a hysteresis model of degradation and recovery, often to novel ecosystems.

Distinguishing globally-driven changes from regional- and local-scale impacts: The case for long-term and broad-scale studies of recovery from pollution

Marine ecosystems are subject to anthropogenic change at global, regional and local scales. Global drivers interact with regional- and local-scale impacts of both a chronic and acute nature. Natural fluctuations and those driven by climate change need to be understood to diagnose local- and regional-scale impacts, and to inform assessments of recovery. Three case studies are used to illustrate the need for long-term studies: (i) separation of the influence of fishing pressure from climate change on bottom fish in the English Channel; (ii) recovery of rocky shore assemblages from the Torrey Canyon oil spill in the southwest of England; (iii) interaction of climate change and chronic Tributyltin pollution affecting recovery of rocky shore populations following the Torrey Canyon oil spill. We emphasize that "baselines" or "reference states" are better viewed as envelopes that are dependent on the time window of observation. Recommendations are made for adaptive management in a rapidly changing world.

An evaluation of carbon offset supplementation options for beef production systems on coastal speargrass in central Queensland, Australia

In 2014, the Australian Government implemented the Emissions Reduction Fund to offer incentives for businesses to reduce greenhouse gas (GHG) emissions by following approved methods. Beef cattle businesses in northern Australia can participate by applying the ‘reducing GHG emissions by feeding nitrates to beef cattle’ methodology and the ‘beef cattle herd management’ methods. The nitrate (NO3) method requires that each baseline area must demonstrate a history of urea use. Projects earn Australian carbon credit units (ACCU) for reducing enteric methane emissions by substituting NO3 for urea at the same amount of fed nitrogen. NO3 must be fed in the form of a lick block because most operations do not have labour or equipment to manage daily supplementation. NO3 concentrations, after a 2-week adaptation period, must not exceed 50 g NO3/adult animal equivalent per day or 7 g NO3/kg dry matter intake per day to reduce the risk of NO3 toxicity. There is also a ‘beef cattle herd management’ method, approved in 2015, that covers activities that improve the herd emission intensity (emissions per unit of product sold) through change in the diet or management. The present study was conducted to compare the required ACCU or supplement prices for a 2% return on capital when feeding a low or high supplement concentration to breeding stock of either (1) urea, (2) three different forms of NO3 or (3) cottonseed meal (CSM), at N concentrations equivalent to 25 or 50 g urea/animal equivalent, to fasten steer entry to a feedlot (backgrounding), in a typical breeder herd on the coastal speargrass land types in central Queensland. Monte Carlo simulations were run using the software @risk, with probability functions used for (1) urea, NO3 and CSM prices, (2) GHG mitigation, (3) livestock prices and (4) carbon price. Increasing the weight of steers at a set turnoff month by feeding CSM was found to be the most cost-effective option, with or without including the offset income. The required ACCU prices for a 2% return on capital were an order of magnitude higher than were indicative carbon prices in 2015 for the three forms of NO3. The likely costs of participating in ERF projects would reduce the return on capital for all mitigation options.

Exposure-response (E-R) analysis to facilitate phase III (P3) dose selection for AMG 479 (A479) in combination with gemcitabine (G) to treat metastatic pancreatic cancer (mPC)

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Background: A479 is an investigational, fully human monoclonal antibody against IGF1R. In a phase II study, 125 pts with mPC were randomized 1:1:1 to A479, placebo (P), or conatumumab in combination with G. Addition of A479 (12 mg/kg IV, Q2W) to G (1000 mg/m2) showed evidence of improved OS and PFS (Kindler, JCO 2010:28 abstr 4035). An E-R analysis was done to inform P3 dose selection for A479.

Methods: A population PK model of A479 was constructed using data from multiple studies. An E-R analysis was performed with pts from the A479+G and P+G arms (∼40 pts/arm). The effect of estimated steady-state area under the curve (AUCss) on OS and PFS was evaluated with a Cox proportional hazard model. Effects of potential confounding factors on OS- AUCss and PFS-AUCss associations were assessed by multivariate analysis. Exposure-safety data were analyzed with descriptive statistics and linear regression. P3 doses for A479 were explored with Monte Carlo simulations using population PK and parametric survival models.

Results: There was a positive association between OS or PFS and higher AUCss in the A479+G arm (P<0.001, <0.001) that remained even when data from the A479+G and P+G arms were combined (P=0.033, 0.022). Pts with AUCss ≥ median (19.2 mg·h/μL) had longer median OS and PFS (16.0, 7.6 months) than pts with AUCss < median (4.7, 1.9 months). OS-AUCss and PFS-AUCss associations were significant after adjusting for potential confounding factors. Sensitivity E-R analyses were done to confirm the modeling results. The incidence of most adverse events was similar between the AUCss < and ≥ median groups, although the incidence of grade ≥3 hyperglycemia, neutropenia, and thrombocytopenia trended higher in pts with AUCss ≥ median. Population PK indicated 1.7-fold higher clearance of A479 in mPC than non-mPC pts. No G-A479 PK interactions were identified. PK simulations showed similar AUCss of A479 in mPC pts at 20 mg/kg and in non-mPC pts at 12 mg/kg. Simulations projected improved OS and PFS with 20 mg/kg vs 12 mg/kg A479.

Conclusions: Increased exposure to A479 is associated with improved clinical outcomes in mPC. This supports the evaluation of 20 mg/kg A479 in P3.

[Table: see text]

NF-kB Complex Activation and Association of αB-Crystallin and Vimentin with Poor Prognosis in Primary Breast Cancer

Background: Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) is a protein complex found in almost all animal cell types and is involved in cellular responses to stimuli such as stress, free radicals, cytokines et.c. NF-kB plays a key role in regulating the immune response and incorrect regulation of NF-kB has been linked to the development of cancer, several inflammatory and autoimmune diseases. The role of NF-kB, its subunits and pathways in breast cancer and in the surrounding stromal tissues remains uncertain. αB-crystallin is a heat shock protein, which function as stress-induced molecular chaperones to inhibit the aggregation of denatured proteins. Previous studies have identified αB-crystallin as a marker of poor prognosis for breast cancer and have suggested that it is an excellent marker for tumours of basal origin. The aim of this study is to examine, for the first time, NF-kB and αB-crystallin, vimentin and HSPs in the same set of breast cancers and stroma and relate this to clinical parameters including outcome.Methods: Tissue Micro Arrays of 0.6mm cores of 246 breast cancers were stained with antibodies to αB-crystallin, vimentin, HSP27 (antibody ERD5) and HSP27 82P and 12 subsequent antibodies for NF-kB (IKKa, Ser276, Ser32/36, 180/181, P52, 1kkygmma, P65, RELB, P100/P52, IkBa, cREL, and P50) and scored using the Quick Score Method.Results: Positive associations have been found between αB-crystallin and IKBA (P=0.001 Fishers exact test (FET)), RELB (P&lt;0.001 (FET)) and SER32/36 (P=0.03 (FET)) whereas Vimentin was positively associated IKBA (P=0.003 (FET)), IKKA (P=0.001 (FET)), P50 (P=0.002 (FET)), RELB (P&lt;0.001 (FET)) and SER32/36 (P=0.01 (FET)). Positive associations have also been found between HSP27 and P50 (P=0.002 (FET)), SER32/36 (P&lt;0.001 (FET)). Antibodies such as 180/181 (P=0.04 Kaplan Meier Log Rank (KM), cREL (P=0.03 (KM)), IKBA (P=0.03 (KM)) and IKKA (P=0.01 (KM)) was associated with good survival and P50 (P=0.002 (KM)) and P65 (P=0.01 (KM)) to poor survival. Expression of αB-crystallin was associated with vimentin (P&lt;0.001 (FET)). Its expression was linked to a low expression of the estrogen receptor. Vimentin expression was associated with estrogen receptor (ER) negative cancers and poor survival (P &lt;0.001 (FET)), P=0.002 (KM Log Rank) respectively). In contrast to αB-crystallin, low expression of HSP27 was associated with low ER and progesterone receptor (PGR).Conclusions: Associations were found between various antibodies within the NF-kB pathway as well as the heat shock proteins αB-crystallin, vimentin and HSP27 with varying implications for overall survival. We aim to clarify the mechanisms to prevent the aggregation of stress-accumulated misfolded proteins and apoptosis resulting better survival.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2143.

The Effect of Neoadjuvant Metformin on Breast Cancer Related Genes Clinical Trial – A Preliminary Result

Other authoring group: Dougal Adamson, Lee Baker, Douglas C Brown, Sally Chalmers, Amanda Degabriele, Janet Flinn, Kenneth Fowler, Avril Gunning, Grahame Hardie, Julie Lindsay, Gillian Little, Denis McLean, Robert Murdoch, Colin Purdie, Marta Reis, Valerie Walker.IntroductionMetformin, used in the treatment of diabetes for 50 years, has been linked to a reduced incidence of breast cancer and to an enhanced pathological response when administered concurrent with neoadjuvant chemotherapy. It has been postulated that the anti-neoplastic effect of metformin is through activation of AMP-activated protein Kinase (AMPK). The aim of this open label, randomised clinical trial was to investigate the effect of neoadjuvant metformin on gene expression in primary breast cancer.MethodsNon-diabetic women with histologically proven, operable, primary invasive breast cancer of ≥1cm in size were offered the trial following regional Research Ethics Committee approval.The trial had 2 arms, A and B: in arm A (8 patients), patients had core biopsies at three time points: one at presentation; one after a week of no treatment (internal control); and a further biopsy at the time of definitive surgery after at least 2 weeks of metformin. In trial arm B (47 patients), patients had core biopsies at two time points: one before randomisation to either take metformin or not, and one at the time of definitive breast surgery. Metformin was given as 500mg o.d. orally for one week, increased to 1g b.d. orally for at least another week and until the day prior to excisional breast surgery.RNA was extracted from formalin fixed cores and examined using a Disease-Specific Array for breast cancer on an Affymetrix platform (ALMAC Diagnostics Group, Craigavon, UK). Subsequent confirmatory polymerase chain reaction and immunohistochemistry techniques were used to examine the histological material.ResultsType of results expected:[Change of target gene expression in response to neoadjuvant metformin; symptomatic drug toxicities; potential for therapeutic effects of metformin in non-diabetic patients in vivo.]Results from the first arm:The triplet of core biopsies from 6/8 (75%) of the A arm patients passed the GeneGhip QC and data integrity assessment. Patients were 41-65 (mean: 53) years, with IDC NST, grade II-III, and all ER positive. 270 genes were differentially expressed significantly by wounding, and 63 by metformin. Among the genes significantly over-expressed by metformin were AMPK-beta and PI3K; and those down regulated by metformin were AMPK-gamma and ADCY1. Samples from the B arm patients are in analysis.ConclusionThe gene expression changes identified in response to neoadjuvant metformin suggest that metformin improves DNA damage recognition and repair and regulates cancer cell metabolism. These results suggest mechanisms by which metformin could be efficacious in the treatment of breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3145.

Scotin expression and survival in breast cancer

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Background: The Scotin gene (3p21.3) is directly trans-activated by p53 in response to ionising radiation and produces a 25kD trans-membrane protein located in the endoplasmic reticulum and nuclear membrane which induces a caspase- dependent apoptosis. This study examines the expression of scotin and scotin isoforms in breast cancer in relation to clinical and pathological parameters. Methods: Scotin was examined in 145 breast cancers by DNA sequencing, nested PCR for mRNA expression and using novel antibodies to scotin (pantropic), the C-terminal or N-terminal domain, and the scotin-5 isoform with western blotting and immunohistochemistry on a tissue microarray of breast cancers. Results: Scotin was mutated in 10% of cancers and mRNA expression lost in a further 10%. Moreover, Scotin-5 was expressed in 40% of cancers, while it was not detectable in normal breast epithelium. We established that Scotin-5 is anti-apoptotic and inhibits scotin-mediated apoptosis. Cytoplasmic staining of scotin on TMAs demonstrated that loss of scotin expression was associated with earlier relapse (Mantel-Cox log rank p<0.01) and poor survival (Mantel-Cox log rank p<0.002). Furthermore, loss of Scotin expression identified 50% of the WTp53 patients or 50% of the ER+ patients who also had a poor survival. Conclusions: Scotin may be used as an independent biomarker in breast cancer. Loss of Scotin function may account for a significant proportion of p53 malfunction even in the presence of wild type p53 in breast cancer and adds a further level of complexity to p53 directed therapy in breast cancer.

No significant financial relationships to disclose.

The clinical relevance of p53 isoforms modifying the effects of p53 mutation on survival from breast cancer

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Background: p53 is a key gene in the development of breast cancer and response to therapy. Nine splice variants of p53 in breast cancer have been identified, with full length p53, p53beta and p53gamma (both 46kD, C terminal truncated proteins) commonly expressed. This study examined the clinical relevance of splice variants in breast cancer. Methods: Tumors from 248 patients with primary breast cancer were examined for mutation with the Roche p53 mutation chip and p53 isoform expression detected by RT-PCR followed by nested PCR; full clinical and pathological data included median follow up of 6.4 years. Results: p53 mutation, identified in 65/248 (26%) cancers, was significantly associated by Chi square test with shorter survival (p=0.001), histological grade 3 (p<0.001) and estrogen receptor (ER) negative cancers (p<0.001), as expected. Expression of p53 beta or p53 gamma mRNA was associated with p53 mutation (p=0.002, Fisher's exact test). Intriguingly, the patient groups with a mutant p53 cancer but expressing p53 gamma or p53 beta or both isoforms had survival curves comparable to patients with cancer containing wild type p53. Similarly, p53 gamma or p53 beta was associated with ER negative cancers (Chi square; p<0.001), but the group of ER negative tumors expressing p53 gamma or p53 beta had improved survival similar to ER positive cancers. Patients with p53 mutant, p53 beta negative and ER negative cancers comprised half of those who died within 3 years of diagnosis. Conclusions: p53 beta or p53 gamma isoform expression in breast cancer is associated with better prognosis and may moderate disease behaviour even in mutant p53 and ER negative cancers. Manipulation of p53 isoforms in breast cancer may thus offer therapeutic potential.

No significant financial relationships to disclose.

Recovery of polluted ecosystems: the case for long-term studies

Recovery of marine ecosystems from pollution has tended to receive less attention than the study of new or continuing impacts, but such studies are important in charting recovery from acute incidents and following legislation to deal with chronic contamination. Recovery is inevitably a long-term process, and where such studies have been made they are often too short-lived. Interest quickly wanes following an acute incident and governmental bodies rapidly switch to new legislative priorities for chronic inputs. We review three case studies: recovery of dogwhelk populations after local extinction by tributyl tin leachates from anti-fouling paints; recovery of rocky shore communities from oil spills; and recovery of estuarine ecosystems from industrial and urban development. We then make some generalisations about recovery processes before making a plea for long-term studies of polluted areas.

Scalar timing without reference memory? Episodic temporal generalization and bisection in humans

Three experiments tested whether the scalar property of timing could occur when humans timed short durations under conditions in which it was unlikely that they developed reference memories of temporal "standards". Experiment 1 used an episodic version of a temporal generalization task where judgements were made of the potential equality of two durations presented on each trial. Unknown to the subject, one of these was always 200, 400, 600, or 800 ms, and the other was of variable duration. Temporal generalization gradients showed the scalar property of superimposition at standard values greater than 200 ms. Experiment 2 used a variant of the "roving bisection" method invented by Rodriguez-Girones and Kacelnik (1998) modified so that the scalar property of timing could be observed empirically. Data from bisection with short/long standard pairs of 100/400, 200/800, and 300/1,200 ms showed nearly perfect scalar-type superimposition. Experiment 3 again used episodic temporal generalization, but durations were never repeated and came from three distinct time ranges. Superimposition was found across these ranges except for the shortest visual stimuli timed. The data suggested that scalar timing could occur in humans in conditions where the formation of reference memories of temporal standards was highly improbable.

Notch pathway: making sense of suppressor of hairless

Suppressor of Hairless (Su(H)) is a DNA-binding protein component of the Notch signalling pathway, thought to be required, with a fragment of the Notch receptor, for target gene activation. Recent studies show that this is only one side of the story: target gene enhancers may be regulated by Su(H) in a variety of different ways.

A model Notch response element detects Suppressor of Hairless-dependent molecular switch

Cell-cell signaling mediated by Notch is critical during many different developmental processes for the specification or restriction of cell fates. Currently, the only known transduction pathway involves a DNA binding protein, Suppressor of Hairless [Su(H)] in Drosophila and CBF1 in mammals, and results in the direct activation of target genes. It has been proposed that in the absence of Notch, Su(H)/CBF1 acts as a repressor and is converted into an activator through interactions with the Notch intracellular domain [1--4]. Recently, we have also suggested that the activation of specific target genes requires synergy between Su(H) and other transcriptional activators [5]. Here we have designed an assay that allows us to directly test these hypotheses in vivo. Our results clearly demonstrate that Su(H) is able to function as the core of a molecular switch, repressing transcription in the absence of Notch and activating in the presence of Notch. In its capacity as an activator, Su(H) can cooperate synergistically with a DNA-bound transcription factor, Grainyhead. These interactions indicate a simple model for Notch target-gene regulation that could explain the precision of gene activation elicited by Notch signaling in different developmental fate decisions.

Dissecting the mechanisms of suppressor of hairless function

Suppressor of Hairless [Su(H)] is a DNA-binding protein that is the main intracellular transducer of the Notch signaling pathway in Drosophila. Several different mechanisms have been proposed to account for the activation of Su(H) by Notch. To further investigate how Su(H) activity is regulated we have used misexpression assays with wild-type Su(H) and with modified forms of Su(H) that contained a nuclear localization signal [Su(H)NLS], a transcriptional activation domain [Su(H)VP16], or a deletion of the domain required for interaction with the antagonist Hairless [Su(H)DeltaH]. Only Su(H)VP16 was able to mimic Notch activation effectively in the Drosophila wing, in agreement with the model that Notch activity normally confers coactivator function on Su(H). Neither nuclear localization nor elimination of Hairless binding was sufficient for activation. The phenotypes produced by overexpression of Su(H)wt and Su(H)NLS indicated a mixture of both increased and reduced Notch pathway activity and point to a role for Su(H) in both activation and repression of gene expression, as has been proposed for the mammalian homologue CBF1. Some phenotypes were equivalent to Notch loss-of-function, with wing-nicks and inhibition of a subset of target genes, which is most consistent with the ectopic proteins displacing a Su(H)-coactivator complex. Conversely, other phenotypes were equivalent to Notch gain-of-function, with wing-overgrowths and ectopic target-gene expression. These effects can be explained by the ectopic Su(H)/Su(H)NLS titrating a repressor complex. The wing-overgrowth phenotype is sensitive to the dose of Hairless and the phenotypes produced by coexpressing Su(H) and Hairless suggest that Hairless could form a component of this repressive complex.

Spatially restricted factors cooperate with notch in the regulation of Enhancer of split genes

Expression of the Drosophila Enhancer of split [E(spl)] genes, and their homologues in other species, is dependent on Notch activation. The seven E(spl) genes are clustered in a single complex and their functions overlap significantly; however, the individual genes have distinct patterns of expression. To investigate how this regulation is achieved and to find out whether there is shared or cross regulation between E(spl) genes, we have analysed the enhancer activity of sequences from the adjacent E(spl)mbeta, E(spl)mgamma and E(spl)mdelta genes and made comparisons to E(spl)m8. We find that although regulatory elements can be shared, most aspects of the expression of each individual gene are recapitulated by small (400-500 bp) evolutionarily conserved enhancers. Activated Notch or a Suppressor of Hairless-VP16 fusion are only sufficient to elicit transcription from the E(spl) enhancers in a subset of locations, indicating a requirement for other factors. In tissue culture cells, proneural proteins synergise with Suppressor of Hairless and Notch to promote expression from E(spl)mgamma and E(spl)m8, but this synergy is only observed in vivo with E(spl)m8. We conclude that additional factors besides the proneural proteins limit the response of E(spl)mgamma in vivo. In contrast to the other genes, E(spl)mbeta exhibits little response to proneural proteins and its high level of activity in the wing imaginal disc suggests that wing-specific factors cooperate with Notch to activate the E(spl)mbeta enhancer. These results demonstrate that Notch activity must be integrated with other transcriptional regulators and, since the activation of target genes is critical in determining the developmental consequences of Notch activity, provide a framework for understanding Notch function in different developmental contexts.

Pattern formation: Wingless on the move

Wingless is a key morphogen in Drosophila. Although it is evident that Wingless acts at a distance from its site of synthesis, there is considerable debate about how the protein travels across a field of cells. Recent studies have provided important new insights into this process, though the issue is still far from being resolved.

Planar polarity: out of joint?

Epithelial structures, such as the wing hairs and ommatidia in Drosophila, are aligned in the plane of the epithelium. This planar polarity requires the transmembrane receptor Frizzled. Recent studies have shed new light on mechanisms that could be involved in generating or transducing the polarity signal.

Time- and dose-related changes in the thickness of skin in the pig after irradiation with single doses of thulium-170 beta particles

Time-related changes in skin thickness have been evaluated in the pig using a noninvasive ultrasound technique after exposure to a range of single doses of 0.97 MeV beta particles from (170)Tm plaques. The reduction in relative skin thickness developed in two phases; the separation into two phases was statistically justified only after 120 Gy (P = 0.04). The first phase was between 12 weeks and 24 weeks after irradiation. No further changes were seen until 48-60 weeks after irradiation, when a second phase of skin thinning was observed. No further changes in relative skin thickness were seen in the follow-up period of 104 weeks. The timing of these phases of relative skin thinning was totally independent of the radiation dose; however, the severity of each phase of radiation-induced skin thinning was related to the dose. The pattern of changes was similar to that reported previously after irradiation with 2.27 MeV beta particles from (90)Sr/(90)Y, but the degree of dermal thinning was less for a similar skin surface dose. From a comparison of the depth-dose distribution of the beta particles from the two radionuclides, it was concluded that the target cell population responsible for both the first and second phase of skin thinning in pig skin after irradiation may be located at approximately 800 microm depth. This corresponds to an area in the reticular dermis in pig skin and may be the appropriate site at which to measure the average dose to the dermal tissue.

Distinct expression patterns of different enhancer of split bHLH genes during embryogenesis of Drosophila melanogaster

E(spl) bHLH genes are targets of the Notch pathway: they are transcriptionally activated in response to the Notch signal. Yet, during imaginal development, additional regulatory factors appear to modulate transcription resulting in different expression patterns. During early embryogenesis all E(spl) bHLH genes are expressed in roughly the same domain, namely the neurogenic ectoderm. Within this region these seven genes show a highly dynamic, yet distinct transcriptional activity. Our analysis further detected tissue specific expression of some E(spl) genes at later embryonic stages. Prominent differences were observed in the dorsolateral and procephalic neuroectodermal regions as well as in the mesoderm. These observations indicate that other factors in addition to the Notch signal participate in the regulation of the individual E(spl) genes not only in imaginal tissues but also during neuroblast specification and other cell fate determination events in the embryo.

Drosophila development: Scalloped and Vestigial take wing

The proteins Scalloped and Vestigial are known from genetic studies to play a part in Drosophila wing development. Recent results show how they interact with each other, and in combination with other transcription factors, to confer specific patterns of expression within the wing.

Notch signalling in Drosophila: three ways to use a pathway

Cell-cell interactions mediated by Notch are critical at multiple stages of development. Our current understanding of the Notch signalling pathway suggests a comparatively simple transduction mechanism. However, this core pathway can be deployed in three different types of developmental process: lateral inhibition, lineage decisions and boundary formation. These illustrate how the activity of the pathway can be modulated both at the cell surface, through availability and effectiveness of ligand interactions, and inside the cell, through effects on the transduction pathway and the responsiveness of target genes.

Homeotic regulation of segment-specific differences in neuroblast numbers and proliferation in the Drosophila central nervous system

The number and pattern of neuroblasts that initially segregate from the neuroectoderm in the early Drosophila embryo is identical in thoracic and abdominal segments. However, during late embryogenesis differences in the numbers of neuroblasts and in the extent of neuroblast proliferation arise between these regions. We show that the homeotic genes Ultrabithorax and abdominal-A regulate these late differences, and that misexpression of either gene in thoracic neuroblasts after segregation is sufficient to induce abdominal behaviour. However, in wild type embryos we only detect abdominal-A and Ultrabithorax proteins in early neuroblasts. Furthermore, transplantation experiments reveal that segment-specific behaviour is determined prior to neuroblast segregation. Thus, the segment-specific differences in neuroblast behaviour seem to be determined in the early embryo, mediated through the expression of homeotic genes in early neuroblasts, and executed in later programmes controlling neuroblast numbers and proliferation.

Feed-back mechanisms affecting Notch activation at the dorsoventral boundary in the Drosophila wing

Notch function is required at the dorsoventral boundary of the developing Drosophila wing for its normal growth and patterning. We find that clones of cells expressing either Notch or its ligands Delta and Serrate in the wing mimic Notch activation at the dorsoventral boundary producing non-autonomous effects on proliferation, and activating expression of the target genes E(spl), wingless and cut. The analysis of these clones reveals several mechanisms important for maintaining and delimiting Notch function at the dorsoventral boundary. First, Notch activation in the wing leads to increased production of Delta and Serrate generating a positive feedback loop that maintains signalling. We propose that during normal development, wingless co-operates with Notch to reinforce this positive feedback and Cut, which is activated by Notch at late stages, acts antagonistically to prevent Delta and Serrate expression. Second, high levels of Delta and Serrate have a dominant negative effect on Notch, so that at late stages Notch can only be activated in cells next to the ligand-producing cells. Thus the combined effects of Notch and its target genes cut and wingless regulate the expression of Notch ligands which restrict Notch activity to the dorsoventral boundary.

Synergy between suppressor of Hairless and Notch in regulation of Enhancer of split m gamma and m delta expression

The Notch signaling pathway is known to regulate cell fate decisions in a variety of organisms from worms to humans. Although several components of the pathway have been characterized, the actual mechanism and molecular results of signaling remain elusive. We have examined the role of the Notch signaling pathway in the transcriptional regulation of two Drosophila Enhancer of split [E(spl)] genes, whose gene products have been shown to be downstream players in the pathway. Using a reporter assay system in Drosophila tissue culture cells, we have observed a significant induction of E(spl) m gamma and m delta expression after cotransfection with activated Notch. Characterization of the 5' regulatory regions of these two genes led to the identification of a number of target sites for the Suppressor of Hairless [Su(H)] protein, a transcription factor activated by Notch signaling. We show that Notch-inducible expression of E(spl) m gamma and m delta both in cultured cells and in vivo is dependent on functional Su(H). Although overexpression of Su(H) augments the level of induction of the reporter genes by activated Notch, Su(H) alone is insufficient to produce high levels of transcriptional activation. Despite the synergy observed between activated Notch and Su(H), the former affects neither the nuclear localization nor the DNA binding activity of the latter.

Notch signalling regulates veinlet expression and establishes boundaries between veins and interveins in the Drosophila wing

The veins in the Drosophila wing have a characteristic width, which is regulated by the activity of the Notch pathway. The expression of the Notch-ligand Delta is restricted to the developing veins, and coincides with places where Notch transcription is lower. We find that this asymmetrical distribution of ligand and receptor leads to activation of Notch on both sides of each vein within a territory of Delta-expressing cells, and to the establishment of boundary cells that separate the vein from adjacent interveins. In these cells, the expression of the Enhancer of split gene m beta is activated and the transcription of the vein-promoting gene veinlet is repressed, thus restricting vein differentiation. We propose that the establishment of vein thickness utilises a combination of mechanisms that include: (1) independent regulation of Notch and Delta expression in intervein and vein territories, (2) Notch activation by Delta in cells where Notch and Delta expression overlaps, (3) positive feedback on Notch transcription in cells where Notch has been activated and (4) repression of veinlet transcription by E(spl)m beta and maintenance of Delta expression by veinlet/torpedo activity.