Multi-omic analysis of Esophageal Adenocarcinoma uncovers candidate therapeutic targets and cancer-selective post-transcriptional regulation

BACKGROUND

Efforts to address the poor prognosis associated with esophageal adenocarcinoma (EAC) have been hampered by a lack of biomarkers to identify early disease and therapeutic targets. Despite extensive efforts to understand the somatic mutations associated with EAC over the past decade, a gap remains in understanding how the atlas of genomic aberrations in this cancer impacts the proteome and which somatic variants are of importance for the disease phenotype.

METHODS

We performed a quantitative proteomic analysis of 23 EACs and matched adjacent normal esophageal and gastric tissues. We explored the correlation of transcript and protein abundance using tissue-matched RNA-seq and proteomic data from 7 patients and further integrated these data with a cohort of EAC RNA-seq data (n=264 patients), EAC whole-genome sequencing (n=454 patients) and external published datasets.

CENTRAL FINDINGS

We quantified protein expression from 5879 genes in EAC and patient-matched normal tissues. Several biomarker candidates with EAC-selective expression were identified including the transmembrane protein GPA33. We further verified the EAC-enriched expression of GPA33 in an external cohort of 115 patients and confirm this as an attractive diagnostic and therapeutic target. To further extend the insights gained from our proteomic data, an integrated analysis of protein and RNA expression in EAC and normal tissues revealed several genes with poorly correlated Protein and RNA abundance, suggesting post-transcriptional regulation of protein expression. These outlier genes including SLC25A30, TAOK2, and AGMAT, only rarely demonstrated somatic mutation suggesting post-transcriptional drivers for this EAC-specific phenotype. AGMAT was demonstrated to be over-expressed at the protein level in EAC compared to adjacent normal tissues with an EAC-selective, post-transcriptional mechanism of regulation of protein abundance proposed.

CONCLUSIONS

By quantitative proteomic analysis we have identified GPA33 as an EAC-selective biomarker. Integrated analysis of proteome, transcriptome, and genome in EAC has revealed several genes with tumor-selective, post-transcriptional regulation of protein expression which may be an exploitable vulnerability.

A Roadmap for the Human Gut Cell Atlas

The number of studies investigating the human gastrointestinal tract using various single-cell profiling methods has increased substantially in the past few years. Although this increase provides a unique opportunity for the generation of the first comprehensive Human Gut Cell Atlas (HGCA), there remains a range of major challenges ahead. Above all, the ultimate success will largely depend on a structured and coordinated approach that aligns global efforts undertaken by a large number of research groups. In this Roadmap, we discuss a comprehensive forward-thinking direction for the generation of the HGCA on behalf of the Gut Biological Network of the Human Cell Atlas. Based on the consensus opinion of experts from across the globe, we outline the main requirements for the first complete HGCA by summarizing existing data sets and highlighting anatomical regions and/or tissues with limited coverage. We provide recommendations for future studies and discuss key methodologies and the importance of integrating the healthy gut atlas with related diseases and gut organoids. Importantly, we critically overview the computational tools available and provide recommendations to overcome key challenges.

MYC sensitises cells to apoptosis by driving energetic demand

The MYC oncogene is a potent driver of growth and proliferation but also sensitises cells to apoptosis, which limits its oncogenic potential. MYC induces several biosynthetic programmes and primary cells overexpressing MYC are highly sensitive to glutamine withdrawal suggesting that MYC-induced sensitisation to apoptosis may be due to imbalance of metabolic/energetic supply and demand. Here we show that MYC elevates global transcription and translation, even in the absence of glutamine, revealing metabolic demand without corresponding supply. Glutamine withdrawal from MRC-5 fibroblasts depletes key tricarboxylic acid (TCA) cycle metabolites and, in combination with MYC activation, leads to AMP accumulation and nucleotide catabolism indicative of energetic stress. Further analyses reveal that glutamine supports viability through TCA cycle energetics rather than asparagine biosynthesis and that TCA cycle inhibition confers tumour suppression on MYC-driven lymphoma in vivo. In summary, glutamine supports the viability of MYC-overexpressing cells through an energetic rather than a biosynthetic mechanism.

Lynch syndrome screening in gynaecological cancers: results of an international survey with recommendations for uniform reporting terminology for mismatch repair immunohistochemistry results

AIMS

Lynch syndrome (LS) is associated with an increased risk of developing endometrial carcinoma (EC) and ovarian carcinoma (OC). There is considerable variability in current practices and opinions related to screening of newly diagnosed patients with EC/OC for LS. An online survey was undertaken to explore the extent of these differences.

METHODS AND RESULTS

An online questionnaire was developed by a panel of experts and sent to all members of the British Association of Gynaecological Pathologists (BAGP) and the International Society of Gynecological Pathologists (ISGyP). Anonymised results were received and analysed. Thirty-six BAGP and 44 ISGyP members completed the survey. More than 90% of respondents were aware of the association of LS with both EC and OC, but 34% were not aware of specific guidelines for LS screening. Seventy-one per cent of respondents agreed that universal screening for LS should be carried out in all newly diagnosed EC cases, with immunohistochemistry (IHC) alone as the preferred approach. Only 36% of respondents currently performed IHC or microsatellite instability testing on all newly diagnosed EC cases, with most of the remaining respondents practising selective screening, based on clinical or pathological features or both. A significant minority of respondents (35%) believed that patient consent was required before performance of mismatch repair (MMR) protein IHC. Almost all respondents favoured the use of standardised terminology for reporting MMR protein staining results, and this is proposed herein.

CONCLUSION

There is wide support for universal LS screening in patients with EC, but this survey highlights areas of considerable variation in practice.

A novel panel of short mononucleotide repeats linked to informative polymorphisms enabling effective high volume low cost discrimination between mismatch repair deficient and proficient tumours

Somatic mutations in mononucleotide repeats are commonly used to assess the mismatch repair status of tumours. Current tests focus on repeats with a length above 15bp, which tend to be somatically more unstable than shorter ones. These longer repeats also have a substantially higher PCR error rate, and tests that use capillary electrophoresis for fragment size analysis often require expert interpretation. In this communication, we present a panel of 17 short repeats (length 7-12bp) for sequence-based microsatellite instability (MSI) testing. Using a simple scoring procedure that incorporates the allelic distribution of the mutant repeats, and analysis of two cohort of tumours totalling 209 samples, we show that this panel is able to discriminate between MMR proficient and deficient tumours, even when constitutional DNA is not available. In the training cohort, the method achieved 100% concordance with fragment analysis, while in the testing cohort, 4 discordant samples were observed (corresponding to 97% concordance). Of these, 2 showed discrepancies between fragment analysis and immunohistochemistry and one was reclassified after re-testing using fragment analysis. These results indicate that our approach offers the option of a reliable, scalable routine test for MSI.

CCPG1 Is a Non-canonical Autophagy Cargo Receptor Essential for ER-Phagy and Pancreatic ER Proteostasis

Mechanisms of selective autophagy of the ER, known as ER-phagy, require molecular delineation, particularly in vivo. It is unclear how these events control ER proteostasis and cellular health. Here, we identify cell-cycle progression gene 1 (CCPG1), an ER-resident protein with no known physiological role, as a non-canonical cargo receptor that directly binds to core autophagy proteins via an LIR motif to mammalian ATG8 proteins and, independently and via a discrete motif, to FIP200. These interactions facilitate ER-phagy. The CCPG1 gene is inducible by the unfolded protein response and thus directly links ER stress to ER-phagy. In vivo, CCPG1 protects against ER luminal protein aggregation and consequent unfolded protein response hyperactivation and tissue injury of the exocrine pancreas. Thus, via identification of this autophagy protein, we describe an unexpected molecular mechanism of ER-phagy and provide evidence that this may be physiologically relevant in ER luminal proteostasis.

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CCPG1 is an ER stress-inducible ER-phagy cargo receptor in mammals

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CCPG1 binds directly to ATG8 proteins and FIP200 via distinct peptide motifs

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CCPG1 lysosomal degradation and ER-phagy both require these interactions

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CCPG1 maintains normal ER luminal proteostasis in pancreatic acinar cells in vivo

Molecular synergy underlies the co-occurrence patterns and phenotype of NPM1-mutant acute myeloid leukemia

NPM1 mutations define the commonest subgroup of acute myeloid leukemia (AML) and frequently co-occur with FLT3 internal tandem duplications (ITD) or, less commonly, NRAS or KRAS mutations. Co-occurrence of mutant NPM1 with FLT3-ITD carries a significantly worse prognosis than NPM1-RAS combinations. To understand the molecular basis of these observations, we compare the effects of the 2 combinations on hematopoiesis and leukemogenesis in knock-in mice. Early effects of these mutations on hematopoiesis show that compound Npm1cA/+;NrasG12D/+ or Npm1cA;Flt3ITD share a number of features: Hox gene overexpression, enhanced self-renewal, expansion of hematopoietic progenitors, and myeloid differentiation bias. However, Npm1cA;Flt3ITD mutants displayed significantly higher peripheral leukocyte counts, early depletion of common lymphoid progenitors, and a monocytic bias in comparison with the granulocytic bias in Npm1cA/+;NrasG12D/+ mutants. Underlying this was a striking molecular synergy manifested as a dramatically altered gene expression profile in Npm1cA;Flt3ITD , but not Npm1cA/+;NrasG12D/+ , progenitors compared with wild-type. Both double-mutant models developed high-penetrance AML, although latency was significantly longer with Npm1cA/+;NrasG12D/+ During AML evolution, both models acquired additional copies of the mutant Flt3 or Nras alleles, but only Npm1cA/+;NrasG12D/+ mice showed acquisition of other human AML mutations, including IDH1 R132Q. We also find, using primary Cas9-expressing AMLs, that Hoxa genes and selected interactors or downstream targets are required for survival of both types of double-mutant AML. Our results show that molecular complementarity underlies the higher frequency and significantly worse prognosis associated with NPM1c/FLT3-ITD vs NPM1/NRAS-G12D-mutant AML and functionally confirm the role of HOXA genes in NPM1c-driven AML.

Abstract A09: A next generation sequencing based microsatellite instability assay suitable for routine risk stratification in colorectal cancer

3-5% of CRCs show microsatellite instability (MSI) caused by germline defects in mismatch repair genes (MMR) predisposing to Lynch syndrome. In addition, 12% of sporadic CRCs show MSI. Currently, MSI is tested using a fragment analysis based assay not suitable for high throughput testing with suboptimal sensitivity and specificity. Knowledge of microsatellite instability affects prognosis (MSI is a positive prognostic factor in stage II CRC), risk stratification (for the affected and at risk relatives in Lynch syndrome), prediction of lymph node involvement (lymph node metastasis is unlikely in stage I MSI positive CRC) and treatment of CRCs (MMR deficient tumours showed observable benefit from PD-1 blocking agent pembrolizumab). For all these important benefits, MSI testing is now recommended for all newly diagnosed CRCs. As a result, development of a high throughput approach is desirable. We have developed and validated a high throughput sequence based MSI assay.

In this study, we tested 17 short (7-12bp) mononucleotide markers (previously identified by our team via an in silico analyses of whole genome sequencing data). These 17 markers were able to discriminate between MSI-high (MSI-H) and microsatellite stable (MSS) cases. To define the optimal parameters to discriminate between MSI-H and MSS samples, we tested these 17 markers across a panel of 141 CRC samples. This allowed us to define a scoring scheme for the 17 markers using allelic imbalance based on a linked SNP (called weighted scoring scheme), which achieved 96% sensitivity and 100% specificity. This scoring scheme was then validated using an independent cohort of 70 CRCs without knowing their MSI status. The assay achieved a 100% sensitivity and specificity.

We provide here a high throughput tool to detect microsatellite instability that is less costly, uses short mononucleotide markers (eliminating the need to test matched normal tissue) and is validated on formalin fixed paraffin embedded (FFPE) samples (similar to routine samples). The ability to test the microsatellite instability status in all the newly diagnosed CRC cases would have a great clinical impact on prognosis, risk stratification and treatment of CRCs.

Citation Format: Ghanim Alhilal, Lisa Redford, Angel Alonso, Sira Moreno, Mark Arends, Anca Oniscu, Ottilia O'Brien, Stephanie Needham, John Burn, Michael Jackson, Mauro Santibanez-Koref. A next generation sequencing based microsatellite instability assay suitable for routine risk stratification in colorectal cancer. [abstract]. In: Proceedings of the AACR Special Conference: Improving Cancer Risk Prediction for Prevention and Early Detection; Nov 16-19, 2016; Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(5 Suppl):Abstract nr A09.

A pathologist's survey on the reporting of sessile serrated adenomas/polyps

AIM

The purpose of this survey was to ascertain reporting habits of pathologists towards sessile serrated adenomas/polyps (SSA/P).

METHODS

A questionnaire designed to highlight diagnostic criteria, approach and clinical implications of SSA/P was circulated electronically to 45 pathologists in the UK and North America.

RESULTS

Forty-three of 45 pathologists agreed to participate. The vast majority (88%) had a special interest in gastrointestinal (GI) pathology, had great exposure to GI polyps in general with 40% diagnosing SSA/P at least once a week if not more, abnormal architecture was thought by all participants to be histologically diagnostic, and 11% would make the diagnosis if a single diagnostic histological feature was present in one crypt only, while a further 19% would diagnose SSA/P in one crypt if more than one diagnostic feature was present. The vast majority agreed that deeper sections were useful and 88% did not feel proliferation markers were useful. More than one-third did not know whether, or did not feel that, their clinicians were aware of the implications of SSA/P.

CONCLUSIONS

98% of pathologists surveyed are aware that SSA/P is a precursor lesion to colorectal cancer, the majority agree on diagnostic criteria, and a significant number feel that there needs to be greater communication and awareness among pathologists and gastroenterologists about SSA/P.

High frequency microsatellite instability has a prognostic value in endometrial endometrioid adenocarcinoma, but only in FIGO stage 1 cases

OBJECTIVES

To analyze the prognostic value of microsatellite instability (MSI) in a population-based study of FIGO stage 1-4 endometrial endometrioid adenocarcinomas.

STUDY DESIGN

Survival analysis in 273 patients of MSI status and clinico-pathologic features. Using a highly sensitive pentaplex polymerase chain reaction to establish MSI status, cases were divided into microsatellite stable (MSS), MSI-low (MSI-L, 1 marker positive) and MSI-high (MSI-H, 2-5 markers positive).

RESULTS

After 61 months median follow-up (1-209), 34 (12.5%) of the patients developed metastases but only 6.4% of the FIGO-1. MSI (especially as MSI-H versus MSS/MSI-Lcombined) was prognostic in FIGO-1 but not in FIGO2-4. The 5 and 10 year recurrence-free survival rates were 98% and 95% in the MSS/MSI-L versus 85% and 73% in the MSI-H patients (P = 0.005).

CONCLUSIONS

MSI-H status assessed by pentaplex polymerase chain reaction is an indicator of poor prognosis in FIGO 1, but not in FIGO 2-4 endometrial endometrioid adenocarcinomas.

Mutant nucleophosmin and cooperating pathways drive leukemia initiation and progression in mice

Acute myeloid leukemia (AML) is a molecularly diverse malignancy with a poor prognosis whose largest subgroup is characterized by somatic mutations in NPM1, which encodes nucleophosmin. These mutations, termed NPM1c, result in cytoplasmic dislocation of nucleophosmin and are associated with distinctive transcriptional signatures, yet their role in leukemogenesis remains obscure. Here we report that activation of a humanized Npm1c knock-in allele in mouse hemopoietic stem cells causes Hox gene overexpression, enhanced self renewal and expanded myelopoiesis. One third of mice developed delayed-onset AML, suggesting a requirement for cooperating mutations. We identified such mutations using a Sleeping Beauty transposon, which caused rapid-onset AML in 80% of mice with Npm1c, associated with mutually exclusive integrations in Csf2, Flt3 or Rasgrp1 in 55 of 70 leukemias. We also identified recurrent integrations in known and newly discovered leukemia genes including Nf1, Bach2, Dleu2 and Nup98. Our results provide new pathogenetic insights and identify possible therapeutic targets in NPM1c+ AML.

The tolerability of rTMS treatment in schizophrenia with respect to cognitive function

INTRODUCTION

The purpose of this study was to assess tolerability and safety of high-frequency rTMS with regard to cognitive performance when conducted as "add-on" treatment in chronic schizophrenia in-patients (n=32).

METHODS

Patients, who were on stable antipsychotic treatment, were randomly assigned to verum or sham condition (double-blind). In the verum group, ten sessions of 10 Hz rTMS with a total of 10 000 stimuli were applied over the left dorsolateral prefrontal cortex (PFC) at 110% of motor threshold over a period of two weeks. The sham group received corresponding sham stimulation. RTMS effects on cognitive performance were assessed with a neuropsychological test battery consisting of the following tests: trail making test A and B (TMT), Wisconsin card sorting test (WCST), D2 attention task and the "short test of general intelligence" (KAI).

RESULTS

No statistically significant deterioration of cognitive performance was observed as a result of rTMS treatment. Moreover it was shown that in the verum group patients with a less favourable performance on the WCST at baseline tend to improve after rTMS treatment with regard to psychopathology as opposed to patients in the control group.

DISCUSSION

The stability of cognitive function suggests good tolerability of rTMS treatment in schizophrenia. The absence of evidence for cognitive deterioration could be due to low and short stimulation parameters.

High frequency microsatellite instability has a prognostic value in endometrial endometrioid adenocarcinoma, but only in FIGO stage 1 cases

OBJECTIVES

to analyze the prognostic value of microsatellite instability (MSI) in a population-based study of FIGO stage 1-4 endometrial endometrioid adenocarcinomas.

STUDY DESIGN

survival analysis in 273 patients of MSI status and clinico-pathologic features. Using a highly sensitive pentaplex polymerase chain reaction to establish MSI status, cases were divided into microsatellite stable (MSS), MSI-low (MSI-L, 1 marker positive) and MSI-high (MSI-H, 2-5 markers positive).

RESULTS

after 61 months median follow-up (1-209), 34 (12.5%) of the patients developed metastases but only 6.4% of the FIGO 1. MSI (especially as MSI-H vs. MSS/MSI-Lcombined) was prognostic in FIGO 1 but not in FIGO 2-4. The 5 and 10 year recurrence-free survival rates were 98% and 95% in the MSS/MSI-L vs. 85% and 73% in the MSI-H patients (p=0.005).

CONCLUSIONS

MSI-H status assessed by pentaplex polymerase chain reaction is an indicator of poor prognosis in FIGO 1, but not in FIGO 2-4 endometrial endometrioid adenocarcinomas.

Repetitive transcranial magnetic stimulation for the treatment of negative symptoms in residual schizophrenia: rationale and design of a sham-controlled, randomized multicenter study

Current meta-analysis revealed small, but significant effects of repetitive transcranial magnetic stimulation (rTMS) on negative symptoms in patients with schizophrenia. There is a need for further controlled, multicenter trials to assess the clinical efficacy of rTMS on negative symptoms in schizophrenia in a larger sample of patients. The objective of this multicenter, randomized, sham-controlled, rater- and patient-blind clinical trial is to investigate the efficacy of 3-week 10-Hz high frequency rTMS add on to antipsychotic therapy, 15 sessions per 3 weeks, 1,000 stimuli per session, stimulation intensity 110% of the individual motor threshold) of the left dorsolateral prefrontal cortex for treating negative symptoms in schizophrenia, and to evaluate the effect during a 12 weeks of follow-up. The primary efficacy endpoint is a reduction of negative symptoms as assessed by the negative sum score of the positive and negative symptom score (PANSS). A sample size of 63 in each group will have 80% power to detect an effect size of 0.50. Data analysis will be based on the intention to treat population. The study will be conducted at three university hospitals in Germany. This study will provide information about the efficacy of rTMS in the treatment of negative symptoms. In addition to psychopathology, other outcome measures such as neurocognition, social functioning, quality of life and neurobiological parameters will be assessed to investigate basic mechanisms of rTMS in schizophrenia. Main limitations of the trial are the potential influence of antipsychotic dosage changes and the difficulty to ensure adequate blinding.

Potential clinical targets of repetitive transcranial magnetic stimulation treatment in schizophrenia

Despite the introduction of atypical antipsychotic drugs, treatment-resistant symptoms still represent a serious problem in schizophrenia. Currently, there is evidence from clinical studies suggesting that treatment with repetitive transcranial magnetic stimulation (rTMS) may improve schizophrenia symptoms. Our review provides an overview of clinical rTMS studies in schizophrenic patients. A systematic search of the literature (Cochrane and Medline databases up to December 2005) was conducted. Most studies showed methodological problems due to their explorative character and small sample sizes. In some studies, a treatment effect of high-frequency rTMS applied over the prefrontal cortex was seen with respect to negative symptoms. On the other hand, low-frequency rTMS in the temporal lobe area might lead to a suppression of auditory hallucinations. It is concluded that larger sham-controlled studies are required to allow an adequate assessment of the clinical and neurobiological effects of rTMS in schizophrenic patients. The currently available data provide insufficient evidence to support the use of rTMS as an adjuvant treatment for schizophrenic psychopathology, but encourage further investigation of rTMS as a novel treatment approach.

[A new method for the treatment of depression: repetitive transcranial magnetic stimulation]

Recent data suggest that repetitive transcranial magnetic stimulation (rTMS) is effective in treating depressive symptoms to a lesser extent compared with classical electroconvulsive therapy. However, rTMS represents an economical and well tolerable procedure in relation to the expenditure of electroconvulsive therapy with anaesthesia. Usually, rTMS is applicated as an add-on-therapy accompanying psychopharmacological treatment. So far, it has predominantly been used for patients with long-standing and so called treatment-refractory symptoms. However, even in the early phase of a depressive episode rTMS would be possibly more effective. In many cases, the standard procedure-application of up to 10 rTMS-sessions will not be enough to produce therapeutic benefit. Therefore rTMS series including up to 20 sessions are recommended. Long-term studies are needed to clarify the role of rTMS for relapse prevention and to determine the optimal frequency and duration of rTMS in such an indication. Although numerous results of newer studies suggest a moderate antidepressive effect of rTMS, its application in daily clinical routine practice cannot be recommended yet. Larger, accurate designed and controlled studies, especially involving patients of old age, are needed to evaluate the true tolerability and effectiveness of rTMS as a new treatment option for depressive symptoms.

Increased expression of minichromosome maintenance protein 2 in active inflammatory bowel disease

OBJECTIVE

Minichromosome maintenance protein 2 (Mcm2) is an accurate indicator of cell cycle entry in tissue samples, but its expression in inflammatory bowel disease (IBD) has not previously been investigated. We have used immunohistochemistry to assess the expression of Mcm2, in comparison to the existing proliferation marker Ki-67, in active IBD and IBD without inflammatory activity.

MATERIALS AND METHODS

For this experimental study, sections from colonic biopsy and resection specimens of 48 patients with IBD (5 inactive/quiescent Crohn's disease (CD), 13 active CD, 19 inactive/quiescent ulcerative colitis (UC) and 11 active UC) and 15 normal controls were immunostained with antibodies to Mcm2 and Ki-67. The percentage of immunopositive epithelial nuclei was determined by calculating a labelling index (LI) for entire glands and for gland thirds (superficial, middle and basal).

RESULTS

The Mcm2 LI was significantly increased in the superficial third of glands in active vs. inactive/quiescent UC (P < 0.0001) and active vs. inactive/quiescent CD (P = 0.001). The Mcm2 LI was significantly greater than the Ki-67 LI in active IBD, both in entire glands (P < 0.0001) and in the superficial third of glands (UC, P = 0.001; CD, P = 0.0002). Mcm2 LIs for entire glands were significantly higher in UC (all cases) compared to CD (all cases) (P = 0.032).

CONCLUSIONS

There is increased cell cycle entry, as indicated by expression of Mcm2 and to a lesser extent Ki-67, in the superficial third of colonic glands in active IBD compared to inactive/quiescent IBD. Detection of Mcm2 may contribute to improved histological assessment of small tissue biopsies and may enable the development of a direct stool-based test for detection of active IBD and potentially for assessment of disease activity.

Baseline blood pressure but not early computed tomography changes predicts major hemorrhage after streptokinase in acute ischemic stroke

BACKGROUND AND PURPOSE

Intracerebral hemorrhage is the most serious complication of thrombolytic therapy for stroke. We explored factors associated with this complication in the Australian Streptokinase Trial.

METHODS

The initial CT scans (< or =4 hours after stroke) of 270 patients were reviewed retrospectively by an expert panel for early signs of ischemia and classified into the following 3 categories: no signs or < or =1/3 or >1/3 of the vascular territory. Hemorrhage on late CT scans was categorized as major or minor on the basis of location and mass effect. Stepwise, backward elimination, multivariate logistic regression analysis was used to identify risk factors for each hemorrhage category.

RESULTS

Major hemorrhage occurred in 21% of streptokinase (SK) and 4% of placebo patients. Predictors of major hemorrhage were SK treatment (odds ratio [OR], 6.40; 95% CI, 2.50 to 16.36) and elevated systolic blood pressure before therapy (OR, 1.03; 95% CI, 1.01 to 1.05). Baseline systolic blood pressure >165 mm Hg in SK-treated patients resulted in a >25% risk of major secondary hemorrhage. Early ischemic CT changes, either < or =1/3 or >1/3, were not associated with major hemorrhage (OR, 1.58; 95% CI, 0.65 to 3.83; and OR, 1.11; 95% CI, 0.45 to 2.76, respectively). Minor hemorrhage occurred in 30% of the SK and 26% of the placebo group. Predictors of minor hemorrhage were male sex, severe stroke, early CT changes, and SK treatment. Ninety-one percent of patients with major hemorrhage deteriorated clinically compared with 23% with minor hemorrhage.

CONCLUSIONS

SK increased the risk of both minor and major hemorrhage. Major hemorrhage was also more likely in patients with elevated baseline systolic blood pressure. However, early CT changes did not predict major hemorrhage. Results from this study highlight the importance of baseline systolic blood pressure as a potential cause of hemorrhage in patients undergoing thrombolysis.

Molecular characteristics of serrated adenomas of the colorectum

BACKGROUND

Serrated adenomas (SAs) of the colorectum combine architectural features of hyperplastic polyps and cytological features of classical adenomas. Molecular studies comparing SAs and classical adenomas suggest that each may be a distinct entity; in particular, it has been proposed that microsatellite instability (MSI) distinguishes SAs from classical adenomas and that SAs and the colorectal cancers arising from them develop along a pathway driven by low level microsatellite instability (MSI-L).

AIMS

To define the molecular characteristics of SAs of the colorectum.

MATERIALS AND METHODS

We analysed 39 SAs from 27 patients, including eight SAs from patients with familial adenomatous polyposis (FAP). We screened these polyps for selected molecular changes, including loss of heterozygosity (LOH) close to APC (5q21) and CRAC1 (15q13-q22), MSI, and mutations of K-ras, APC, p53, and beta-catenin. Expression patterns of beta-catenin, p53, MLH1, MSH2, E-cadherin, and O(6)-methylguanine DNA methyltransferase (MGMT) were assessed by immunohistochemistry. Comparative genomic hybridisation was performed on several polyps.

RESULTS

MSI was rare (<5% cases) and there was no loss of expression of mismatch repair proteins. Wnt pathway abnormalities (APC mutation/LOH, beta-catenin mutation/nuclear expression) occurred in 11 SAs, including 6/31 (19%) non-FAP tumours. CRAC1 LOH occurred in 23% of tumours. K-ras mutations and p53 mutations/overexpression were found in 15% and 8% of SAs, respectively. Loss of MGMT expression occurred in 18% of polyps and showed a borderline association with K-ras mutations. Aberrant E-cadherin expression was found in seven polyps. Comparative genomic hybridisation detected no gains or deletions of chromosomal material.

CONCLUSIONS

The serrated pathway of colorectal tumorigenesis appears to be heterogeneous. In common with classical adenomas, some SAs develop along pathways involving changes in APC/beta-catenin. SAs rarely show MSI or any evidence of chromosomal-scale genetic instability. K-ras mutations may however be less common in SAs than in classical adenomas. Some SAs may harbour changes in the CRAC1 gene. Changes in known genes do not account for the growth of the majority of SAs.

Rho-regulated signals induce apoptosis in vitro and in vivo by a p53-independent, but Bcl2 dependent pathway

Rho proteins are a branch of GTPases that belongs to the Ras superfamily which are critical elements of signal transduction pathways leading to a variety of cellular responses. This family of small GTPases has been involved in diverse biological functions such as cytoskeleton organization, cell growth and transformation, cell motility, migration, metastasis, and responses to stress. We report that several human Rho proteins including Rho A, Rho C and Rac 1, are capable of inducing apoptosis in different cell systems like murine NIH3T3 fibroblasts and the human erythroleukemia K562 cell line. Since K562 cells are devoid of p53, apoptosis induced by Rho in this system is independent of p53. Rho-dependent apoptosis is mediated by the generation of ceramides, and it is drastically inhibited by ectopic expression of Bcl2, both under in vitro and in vivo conditions. Furthermore, the human oncogenes vav and ost that have been shown to function as guanine exchange factors for Rho proteins, were also able to induce apoptosis under similar conditions. Finally, we also report that the levels of endogenous Rho proteins are increased when U937 myeloid leukemia cells are exposed to apoptosis-inducing conditions such as TNF alpha treatment. Furthermore, TNF alpha-induced apoptosis in these cells is inhibited by expression of a dominant negative mutant of Rac 1 but it is not affected by a similar mutant of Rho A. These results suggest that Rho proteins play an important role in the physiological regulation of the apoptotic response to stress-inducing agents.

Induction of apoptosis in NIH3T3 cells after serum deprivation by overexpression of rho-p21, a GTPase protein of the ras superfamily

Oncogenes appear to influence apoptosis in two ways. Some activate cells from a growth-arrested state to one in which both apoptosis and entry to S-phase become possible, the choice between them being determined by a second signal, such as cytokine or growth factor. Cells in this state are often sensitive to apoptosis induced by a wide variety of agents, including several drugs used in cancer chemotherapy. Other oncogenes prevent activation of the apoptosis effector pathway, even in the presence of a death stimulus, the affected cells therefore being resistant to chemotherapeutic agents. In rodent fibroblasts, c-myc or the adenovirus oncogene E1A effect the first type of change, whereas bcl-2, v-abl, E1B or activated ras effect the second. Here we study in rodent fibroblast the effect of expression of rho genes, members of the ras superfamily which we have previously shown to be tumorigenic when highly expressed in this cell type. We show that expression of wild-type rho from Aplysia californica stimulates apoptosis in cultured cell lines and that the apoptotic index in tumors generated by these cell lines is similar to those induced by E1A-transformed cells. In contrast, mutated rho, activated by Val14 substitution in the GTP binding site, it less potent as a stimulator of apoptosis, generating a phenotype more similar to that obtained with activated ras. Thus, rho genes may play a critical role in the regulation of apoptosis.

Antiperinuclear factor, a marker autoantibody for rheumatoid arthritis: colocalisation of the perinuclear factor and profilaggrin

The antiperinuclear factor, an autoantibody specific for rheumatoid arthritis, was found in 51/63 (81%) patients with rheumatoid arthritis by indirect immunofluorescence on human buccal mucosa cells. The sensitivity of the antiperinuclear factor test was increased by pretreating the buccal mucosa cells with 0.5% Triton-X100. The specificity of the test for rheumatoid arthritis as compared with control serum samples was maintained. The localisation of the perinuclear factor in the keratohyalin granules of the buccal mucosa cells was verified by immunoelectron microscopy. The perinuclear factor was found to be an insoluble protein whose antigenicity was sensitive to various fixation procedures. In serum samples from patients with rheumatoid arthritis there was a positive correlation between the presence of antiperinuclear factor and the presence of the so called antikeratin antibodies as detected by immunofluorescence on unfixed rat oesophagus cryostat sections. No relation was found between the presence of the perinuclear factor and either the rheumatoid factor, Epstein-Barr virus components, or any cytokeratin. By double immunofluorescence an exact colocalisation of the perinuclear factor and profilaggrin was found. Although the precise biochemical identity of the perinuclear factor remains unclear, our results suggest that it is a protein only present in the fully differentiated squamous epithelial cell layer.

Experimental autoimmune retinitis in the rat induced by immunization with rhodopsin: an ultrastructural study

Experimental autoimmune retinitis induced by immunization with rhodopsin was investigated in the Lewis rat using transmission electron microscopy and light microscopy. The first signs of retinitis consisted of scattered infiltrations of lymphocytes and other mononuclear cells, predominantly in the inner nuclear layer and outer plexiform layer. Occasionally, some macrophages were detected in the photoreceptor cell layer. Eyes exhibiting a clinically moderate or severe inflammation contained areas of normal retina coexistent with mildly to severely inflamed foci. The central retina was more frequently affected than the peripheral area. In moderately inflamed foci, macrophages infiltrated the photoreceptor cell layer, damaging and eliminating its structures. Inflammatory cells penetrated the photoreceptor outer segment layer which remained unaltered so far in spite of a high serum anti-(rhod)opsin antibody titer. In stages of severe inflammation, massive infiltrations of macrophages and polymorphonuclear cells destroyed the photoreceptor cells focally, leaving the retinal pigment epithelium virtually unaffected. Adjacent to these foci the pigment epithelial cells sometimes exhibited increased numbers of phagosomes and swelling. The locations of the cell infiltrations and lesions in progressive stages of development suggest that the rod outer segments are the target for the autoimmune damage. The described patterns of inflammation were compared with those of previous studies using other animal species and inciting antigens. Especially in rhodopsin-induced retinitis, the blood-retina barrier at the level of the Bruch's membrane/pigment epithelium appears to be highly resistant to cytotoxic cells. The present observations are in agreement with the concept that the cellular immune response plays a major role in the pathogenesis of (rhod)opsin-induced retinitis.