Epitope Lability of Phosphorylated Biomarkers of the DNA Damage Response Pathway Results in Increased Vulnerability to Effects of Delayed or Incomplete Formalin Fixation

Phosphorylated biomarkers are crucial for our understanding of drug mechanism of action and dose selection during clinical trials, particularly for drugs that target protein kinases, such as DNA-damage-response (DDR) inhibitors. However, tissue fixation conditions needed to preserve DDR-specific phospho-biomarkers have not been previously investigated. Using xenograft tissues and tightly controlled formalin fixation conditions, we assessed how preanalytical factors affect phosphorylated DDR biomarkers pRAD50(Ser635), ɣH2AX(Ser139), pKAP1(Ser824), and non-phosphorylated biomarkers cMYC and ATM. Cold ischemia times ranged from 15 min to 6 hr, and the fixation duration ranged from 24 hr to 4 weeks. Epitopes pRAD50 and pKAP1 appeared the most labile assessed with staining loss after just 15 min of cold ischemia time, while ATM was more robust showing consistent expression up to 1 hr of cold ischemia. Notably, ɣH2AX expression was lost with formalin fixation over 48 hr. The use of core needle biopsies where possible and novel fixation methods such as the 2-step temperature-controlled formalin approach may improve phosphorylated biomarker preservation; however, practical challenges may affect wider clinical application. The most essential tissue-processing step when downstream analysis includes DDR phosphorylated biomarkers is immediate tissue submersion in formalin, without delay, upon excision from the patient, followed by room temperature fixation for 24 hr.

Minimizing Sample Failure Rates for Challenging Clinical Tumor Samples

Identification of somatic variants in cancer by high-throughput sequencing has become common clinical practice, largely because many of these variants may be predictive biomarkers for targeted therapies. However, there can be high sample quality control (QC) failure rates for some tests that prevent the return of results. Stem-loop inhibition mediated amplification (SLIMamp) is a patented technology that has been incorporated into commercially available cancer next-generation sequencing testing kits. The claimed advantage is that these kits can interrogate challenging formalin-fixed, paraffin-embedded tissue samples with low tumor purity, poor-quality DNA, and/or low-input DNA, resulting in a high sample QC pass rate. The study aimed to substantiate that claim using Pillar Biosciences oncoReveal Solid Tumor Panel. Forty-eight samples that had failed one or more preanalytical QC sample parameters for whole-exome sequencing from the Australian Translational Genomics Center's ISO15189-accredited diagnostic genomics laboratory were acquired. XING Genomic Services performed an exploratory data analysis to characterize the samples and then tested the samples in their ISO15189-accredited laboratory. Clinical reports could be generated for 37 (77%) samples, of which 29 (60%) contained clinically actionable or significant variants that would not otherwise have been identified. Eleven samples were deemed unreportable, and the sequencing data were likely dominated by artifacts. A novel postsequencing QC metric was developed that can discriminate between clinically reportable and unreportable samples.

Retrospective analysis of Schlafen11 (SLFN11) to predict the outcomes to therapies affecting the DNA damage response

Background

The absence of the putative DNA/RNA helicase Schlafen11 (SLFN11) is thought to cause resistance to DNA-damaging agents (DDAs) and PARP inhibitors.

Methods

We developed and validated a clinically applicable SLFN11 immunohistochemistry assay and retrospectively correlated SLFN11 tumour levels to patient outcome to the standard of care therapies and olaparib maintenance.

Results

High SLFN11 associated with improved prognosis to the first-line treatment with DDAs platinum-plus-etoposide in SCLC patients, but was not strongly linked to paclitaxel–platinum response in ovarian cancer patients. Multivariate analysis of patients with relapsed platinum-sensitive ovarian cancer from the randomised, placebo-controlled Phase II olaparib maintenance Study19 showed SLFN11 tumour levels associated with sensitivity to olaparib. Study19 patients with high SLFN11 had a lower progression-free survival (PFS) hazard ratio compared to patients with low SLFN11, although both groups had the benefit of olaparib over placebo. Whilst caveated by small sample size, this trend was maintained for PFS, but not overall survival, when adjusting for BRCA status across the olaparib and placebo treatment groups, a key driver of PARP inhibitor sensitivity.

Conclusion

We provide clinical evidence supporting the role of SLFN11 as a DDA therapy selection biomarker in SCLC and highlight the need for further clinical investigation into SLFN11 as a PARP inhibitor predictive biomarker.

Intratumoral Transcriptome Heterogeneity Is Associated With Patient Prognosis and Sidedness in Patients With Colorectal Cancer Treated With Anti-EGFR Therapy From the CO.20 Trial

PURPOSE

Metastatic colorectal cancers (mCRCs) assigned to the transit-amplifying (TA) CRCAssigner subtype are more sensitive to anti-epidermal growth factor receptor (EGFR) therapy. We evaluated the association between the intratumoral presence of TA signature (TA-high/TA-low, dubbed as TA-ness classification) and outcomes in CRCs treated with anti-EGFR therapy.

PATIENTS AND METHODS

The TA-ness classes were defined in a discovery cohort (n = 84) and independently validated in a clinical trial (CO.20; cetuximab monotherapy arm; n = 121) and other samples using an established NanoString-based gene expression assay. Progression-free survival (PFS), overall survival (OS), and disease control rate (DCR) according to TA-ness classification were assessed by univariate and multivariate analyses.

RESULTS

The TA-ness was measured in 772 samples from 712 patients. Patients (treated with anti-EGFR therapy) with TA-high tumors had significantly longer PFS (discovery hazard ratio [HR], 0.40; 95% CI, 0.25 to 0.64; P < .001; validation HR, 0.65; 95% CI, 0.45 to 0.93; P = .018), longer OS (discovery HR, 0.48; 95% CI, 0.29 to 0.78; P = .003; validation HR, 0.67; 95% CI, 0.46 to 0.98; P = .04), and higher DCR (discovery odds ratio [OR]; 14.8; 95% CI, 4.30 to 59.54; P < .001; validation OR, 4.35; 95% CI, 2.00 to 9.09; P < .001). TA-ness classification and its association with anti-EGFR therapy outcomes were further confirmed using publicly available data (n = 80) from metastatic samples (PFS P < .001) and patient-derived xenografts (P = .042). In an exploratory analysis of 55 patients with RAS/BRAF wild-type and left-sided tumors, TA-high class was significantly associated with longer PFS and trend toward higher response rate (PFS HR, 0.53; 95% CI, 0.28 to 1.00; P = .049; OR, 5.88; 95% CI, 0.71 to 4.55; P = .09; response rate 33% in TA-high and 7.7% in TA-low).

CONCLUSION

TA-ness classification is associated with prognosis in patients with mCRC treated with anti-EGFR therapy and may further help understanding the value of sidedness in patients with RAS/BRAF wild-type tumors.

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1-3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10-18.

Clinical Utility of Real-Time Targeted Molecular Profiling in the Clinical Management of Ovarian Cancer: The ALLOCATE Study

PURPOSE

The ALLOCATE study was designed as a pilot to demonstrate the feasibility and clinical utility of real-time targeted molecular profiling of patients with recurrent or advanced ovarian cancer for identification of potential targeted therapies.

PATIENTS AND METHODS

A total of 113 patients with ovarian cancer of varying histologies were recruited from two tertiary hospitals, with 99 patient cases suitable for prospective analysis. Targeted molecular and methylation profiling of fresh biopsy and archived tumor samples were performed by screening for mutations or copy-number variations in 44 genes and for promoter methylation of BRCA1 and RAD51C.

RESULTS

Somatic genomic or methylation events were identified in 85% of all patient cases, with potentially actionable events with defined targeted therapies (including four resistance events) detected in 60% of all patient cases. On the basis of these findings, six patients received molecularly guided therapy, three patients had unsuspected germline cancer–associated BRCA1/ 2 mutations and were referred for genetic counseling, and two intermediate differentiated (grade 2) serous ovarian carcinomas were reclassified as low grade, leading to changes in clinical management. Additionally, secondary reversion mutations in BRCA1/ 2 were identified in fresh biopsy samples of two patients, consistent with clinical platinum/poly (ADP-ribose) polymerase inhibitor resistance. Timely reporting of results if molecular testing is done at disease recurrence, as well as early referral for patients with platinum-resistant cancers, were identified as factors that could improve the clinical utility of molecular profiling.

CONCLUSION

ALLOCATE molecular profiling identified known genomic and methylation alterations of the different ovarian cancer subtypes and was deemed feasible and useful in routine clinical practice. Better patient selection and access to a wider range of targeted therapies or clinical trials will further enhance the clinical utility of molecular profiling.

PI3K activation in neural stem cells drives tumorigenesis which can be ameliorated by targeting the cAMP response element binding protein

Background

Hyperactivation of phosphoinositide 3-kinase (PI3K) signaling is common in cancers, but the precise role of the pathway in glioma biology remains to be determined. Some understanding of PI3K signaling mechanisms in brain cancer comes from studies on neural stem/progenitor cells (NSPCs), where signals transmitted via the PI3K pathway cooperate with other intracellular pathways and downstream transcription factors to regulate critical cell functions.

Methods

To investigate the role of the PI3K pathway in glioma initiation and development, we generated a mouse model targeting the inducible expression of a PIK3CAH1047A oncogenic mutant and deletion of the PI3K negative regulator, phosphatase and tensin homolog (PTEN), to NSPCs.

Results

Expression of a Pik3caH1047A was sufficient to generate tumors with oligodendroglial features, but simultaneous loss of PTEN was required for the development of invasive, high-grade glioma. Pik3caH1047A-PTEN mutant NSPCs exhibited enhanced neurosphere formation which correlated with increased Wnt signaling, while loss of cAMP response element binding protein (CREB) in Pik3caH1047A-Pten mutant tumors led to longer symptom-free survival in mice.

Conclusion

Taken together, our findings present a novel mouse model for glioma demonstrating that the PI3K pathway is important for initiation of tumorigenesis and that disruption of downstream CREB signaling attenuates tumor expansion.

An evaluation of the challenges to developing tumor BRCA1 and BRCA2 testing methodologies for clinical practice

Ovarian cancer patients with germline or somatic pathogenic variants benefit from treatment with poly ADP ribose polymerase (PARP) inhibitors. Tumor BRCA1/2 testing is more challenging than germline testing as the majority of samples are formalin-fixed paraffin embedded (FFPE), the tumor genome is complex, and the allelic fraction of somatic variants can be low. We collaborated with 10 laboratories testing BRCA1/2 in tumors to compare different approaches to identify clinically important variants within FFPE tumor DNA samples. This was not a proficiency study but an inter-laboratory comparison to identify common issues. Each laboratory received the same tumor DNA samples ranging in genotype, quantity, quality, and variant allele frequency (VAF). Each laboratory performed their preferred next-generation sequencing method to report on the variants. No false positive results were reported in this small study and the majority of methods detected the low VAF variants. A number of variants were not detected due to the bioinformatics analysis, variant classification, or insufficient DNA. The use of hybridization capture or short amplicon methods are recommended based on a bioinformatic assessment of the data. The study highlights the importance of establishing standards and standardization for tBRCA testing particularly when the test results dictate clinical decisions regarding life extending therapies.

Preparing for genomic medicine: a real world demonstration of health system change

Organisations and governments seeking to implement genomics into clinical practice face numerous challenges across multiple, diverse aspects of the health care system. It is not sufficient to tackle any one aspect in isolation: to create a system that supports genomic medicine, they must be addressed simultaneously. The growing body of global knowledge can guide decision-making, but each jurisdiction or organisation needs a model for genomic (or personalised) medicine that is tailored to its unique context, its priorities and the funds available. Poor decisions could greatly reduce the benefits that could potentially arise from genomic medicine. Demonstration projects enable models to be tested, providing valuable evidence and experience for subsequent implementation. Here, we present the Melbourne Genomics Health Alliance demonstration project as an exemplar of a collaborative, holistic approach to phased implementation of genomics across multiple autonomous institutions. The approach and lessons learned may assist others in determining how best to integrate genomics into their healthcare system.

Clustered somatic mutations are frequent in transcription factor binding motifs within proximal promoter regions in melanoma and other cutaneous malignancies

Most cancer DNA sequencing studies have prioritized recurrent non-synonymous coding mutations in order to identify novel cancer-related mutations. Although attention is increasingly being paid to mutations in non-coding regions, standard approaches to identifying significant mutations may not be appropriate and there has been limited analysis of mutational clusters in functionally annotated non-coding regions. We sought to identify clustered somatic mutations (hotspot regions across samples) in functionally annotated regions in melanoma and other cutaneous malignancies (cutaneous squamous cell carcinoma, basal cell carcinoma and Merkel cell carcinoma). Sliding window analyses revealed numerous recurrent clustered hotspot mutations in proximal promoters, with some specific clusters present in up to 25% of cases. Mutations in melanoma were clustered within ETS and Sp1 transcription factor binding motifs, had a UV signature and were identified in other cutaneous malignancies. Clinicopathologic correlation and mutation analysis support a causal role for chronic UV irradiation generating somatic mutations in transcription factor binding motifs of proximal promoters.

Response to Cetuximab With or Without Irinotecan in Patients With Refractory Metastatic Colorectal Cancer Harboring the KRAS G13D Mutation: Australasian Gastro-Intestinal Trials Group ICECREAM Study

Purpose

RAS mutations predict lack of response to epidermal growth factor receptor monoclonal antibody therapy in patients with metastatic colorectal cancer (mCRC), but preclinical studies and retrospective clinical data suggest that patients with tumors harboring the exon 2 KRAS G13D mutation may benefit from cetuximab. We aimed to assess cetuximab monotherapy and cetuximab plus irinotecan in patients with molecularly selected (G13D mutation) chemotherapy-refractory mCRC in a randomized phase II trial of this rare molecular subtype.

Patients and Methods

Patients with chemotherapy-refractory KRAS G13D mutation–positive mCRC who had progressed within 6 months of irinotecan therapy were randomly assigned to cetuximab 400 mg/m2 loading dose and then 250 mg/m2 once per week with or without irinotecan 180 mg/m2 once every 2 weeks. The primary end point was 6-month progression-free survival; secondary end points were response rate, overall survival, quality of life, and toxicity.

Results

Fifty-one of 53 patients recruited over 2 years were eligible. The 6-month progression-free survival rate was 10% (95% CI, 2% to 26%) for cetuximab versus 23% (95% CI, 9% to 40%) for cetuximab plus irinotecan with a hazard ratio of 0.74 (95% CI, 0.42 to 1.32). Response and stable disease rates were 0% and 58% for monotherapy versus 9% and 70% for combination treatment, respectively. Overall survival and quality of life were similar; toxicities were higher with combination therapy.

Conclusion

In patients with G13D-mutated chemotherapy-refractory mCRC, there was no statistically significant improvement in disease control at 6 months with either cetuximab monotherapy or cetuximab plus irinotecan. No responses were seen with single-agent cetuximab. The responses observed with the combination of cetuximab and irinotecan may reflect true drug synergy or persistent irinotecan sensitivity. The ICECREAM (Irinotecan Cetuximab Evaluation and Cetuximab Response Evaluation Among Patients with a G13D Mutation) study demonstrates the need to prospectively evaluate hypotheses that were previously supported by retrospective analyses and exemplifies the value of international collaboration in trials of rare molecular subtypes.

High-Throughput Amplicon-Based Copy Number Detection of 11 Genes in Formalin-Fixed Paraffin-Embedded Ovarian Tumour Samples by MLPA-Seq

Whilst next generation sequencing can report point mutations in fixed tissue tumour samples reliably, the accurate determination of copy number is more challenging. The conventional Multiplex Ligation-dependent Probe Amplification (MLPA) assay is an effective tool for measurement of gene dosage, but is restricted to around 50 targets due to size resolution of the MLPA probes. By switching from a size-resolved format, to a sequence-resolved format we developed a scalable, high-throughput, quantitative assay. MLPA-seq is capable of detecting deletions, duplications, and amplifications in as little as 5ng of genomic DNA, including from formalin-fixed paraffin-embedded (FFPE) tumour samples. We show that this method can detect BRCA1, BRCA2, ERBB2 and CCNE1 copy number changes in DNA extracted from snap-frozen and FFPE tumour tissue, with 100% sensitivity and >99.5% specificity.

AmpliVar: mutation detection in high-throughput sequence from amplicon-based libraries

Conventional means of identifying variants in high-throughput sequencing align each read against a reference sequence, and then call variants at each position. Here, we demonstrate an orthogonal means of identifying sequence variation by grouping the reads as amplicons prior to any alignment. We used AmpliVar to make key-value hashes of sequence reads and group reads as individual amplicons using a table of flanking sequences. Low-abundance reads were removed according to a selectable threshold, and reads above this threshold were aligned as groups, rather than as individual reads, permitting the use of sensitive alignment tools. We show that this approach is more sensitive, more specific, and more computationally efficient than comparable methods for the analysis of amplicon-based high-throughput sequencing data. The method can be extended to enable alignment-free confirmation of variants seen in hybridization capture target-enrichment data.

Ubiquitous expression of the Pik3caH1047R mutation promotes hypoglycemia, hypoinsulinemia, and organomegaly

Mutations in PIK3CA, the gene encoding the p110α catalytic subunit of PI3K, are among the most common mutations found in human cancer and have also recently been implicated in a range of overgrowth syndromes in humans. We have used a novel inducible "exon-switch" approach to knock in the constitutively active Pik3ca(H1047R) mutation into the endogenous Pik3ca gene of the mouse. Ubiquitous expression of the Pik3ca(H1047R) mutation throughout the body resulted in a dramatic increase in body weight within 3 weeks of induction (mutant 150 ± 5%; wild-type 117 ± 3%, mean ± sem), which was associated with increased organ size rather than adiposity. Severe metabolic effects, including a reduction in blood glucose levels to 59 ± 4% of baseline (11 days postinduction) and undetectable insulin levels, were also observed. Pik3ca(H1047R) mutant mice died earlier (median survival 46.5 d post-mutation induction) than wild-type control mice (100% survival > 250 days). Although deletion of Akt2 increased median survival by 44%, neither organ overgrowth, nor hypoglycemia were rescued, indicating that both the growth and metabolic functions of constitutive PI3K activity can be Akt2 independent. This mouse model demonstrates the critical role of PI3K in the regulation of both organ size and glucose metabolism at the whole animal level.

Resistance to CDK2 inhibitors is associated with selection of polyploid cells in CCNE1-amplified ovarian cancer

PURPOSE

Amplification of cyclin E1 (CCNE1) is associated with poor outcome in breast, lung, and other solid cancers, and is the most prominent structural variant associated with primary treatment failure in high-grade serous ovarian cancer (HGSC). We have previously shown that CCNE1-amplified tumors show amplicon-dependent sensitivity to CCNE1 suppression. Here, we explore targeting CDK2 as a novel therapeutic strategy in CCNE1-amplified cancers and mechanisms of resistance.

EXPERIMENTAL DESIGN

We examined the effect of CDK2 suppression using RNA interference and small-molecule inhibitors in SK-OV-3, OVCAR-4, and OVCAR-3 ovarian cancer cell lines. To identify mechanisms of resistance, we derived multiple, independent resistant sublines of OVCAR-3 to CDK2 inhibitors. Resistant cells were extensively characterized by gene expression and copy number analysis, fluorescence-activated cell sorting profiling and conventional karyotyping. In addition, we explored the relationship between CCNE1 amplification and polyploidy using data from primary tumors.

RESULTS

We validate CDK2 as a therapeutic target in CCNE1-amplified cells by showing selective sensitivity to suppression, either by gene knockdown or using small-molecule inhibitors. In addition, we identified two resistance mechanisms, one involving upregulation of CDK2 and another novel mechanism involving selection of polyploid cells from the pretreatment tumor population. Our analysis of genomic data shows that polyploidy is a feature of cancer genomes with CCNE1 amplification.

CONCLUSIONS

These findings suggest that cyclinE1/CDK2 is an important therapeutic target in HGSC, but that resistance to CDK2 inhibitors may emerge due to upregulation of CDK2 target protein and through preexisting cellular polyploidy.

Abstract C27: Detection of the BRAF V600E mutation in colon cancer and thyroid cancer by immunohistochemistry

Background: The most common of all activating BRAF mutations (T1799A point mutation) leads to a substitution of valine (V) to glutamic acid (E) at the position 600 of the amino acid sequence. This oncogenic mutation in the BRAF gene constitutively activates the MAPK signaling pathway and results in increased proliferation and inhibition of apoptosis. Currently, the gold standard is sequencing of the tumor DNA, but this method is not practical for routine practice. In contrast, immunohistochemistry (IHC) is a relatively easy diagnostic tool to detect proteins in paraffin-embedded tissues. The major goal of this study was to compare detection of BRAF V600E by sequencing and IHC using anti-BRAF V600E (VE1) antibody. This antibody is mutation specific and can distinguish the V600E mutation in BRAF from the wild type BRAF protein.

Methods: Tissues from 352 patients with colon cancer (N=279) and thyroid cancer (N=73) were evaluated for the BRAF V600E mutation. Genomic DNA was extracted from 20 μm tissue sections and analyzed by PCR amplification followed by DNA sequencing. Immunohistochemical staining using anti-BRAF V600E (VE1) antibody was done on VENTANA BenchMark XT platform with OptiView DAB IHC Detection Kit. Furthermore, the effect of six different fixatives, time of fixation and ischemia on BRAF V600E staining intensity was evaluated in two mouse xenograft models since the BRAF V600E antigen may be affected by fixation conditions or delay to fixation,.

Results: In our cohort 212 cases were negative for BRAF V600E mutation by IHC. Out of these 212 cases 206 cases (97.2%) were also negative for BRAF V600E mutation by sequencing and 6 cases (2.8%) were discordant. Of the 140 cases that were IHC positive for BRAF V600E mutation, 133 cases were confirmed by sequencing (95.0%) and 7 cases were discordant (5.0%). Overall, there was high concordance between IHC and DNA sequencing: negative predictive value was 97.2%, positive predictive value was 95.0%, sensitivity was 95.7%, and specificity was 96.7%. The overall percentage agreement across all cases was 96.6% (339/352 cases). In addition, tissue fixation studies indicate that 10% neutral buffered formalin or zinc formalin are the only appropriate fixatives and tissues should be fixed within 2 hours following tissue collection.

Conclusion: In summary, our data indicate that there is high concordance between sequencing and IHC using anti-BRAF V600E (VE1) antibody for the detection of the BRAF V600E mutation in colorectal cancer and thyroid cancer in FFPE tissues. In addition, these studies demonstrated that the appropriate tissue fixation protocol is critical for BRAF V600E immunohistochemical studies. Overall, IHC with anti-BRAF V600E (VE1) antibody is highly sensitive and specific detection method for determination of BRAF V600E mutation.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C27.

Citation Format: Katerina Dvorak, John Palting, Paul M. Waring. Detection of the BRAF V600E mutation in colon cancer and thyroid cancer by immunohistochemistry. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C27.

Mutation detection by clonal sequencing of PCR amplicons and grouped read typing is applicable to clinical diagnostics

We describe a sensitive technique for mutation detection using clonal sequencing. We analyzed DNA extracted from 13 cancer cell lines and 35 tumor samples and applied a novel approach to identify disease-associated somatic mutations. By matching reads against an index of known variants, noise can be dramatically reduced, enabling the detection and quantification of those variants, even when they are present at less than 1% of the total sequenced population; this is comparable to, or better than, current diagnostic methods. Following the identification or exclusion of known variants, unmatched reads are grouped for BLAST searching to identify novel variants or contaminants. Known variants, novel variants, and contaminants were readily identified in tumor tissue using this approach. Our approach also enables an estimation of the per-base sequencing error rate, providing a confidence threshold for interpretation of the results in the clinic. This novel approach has immediate applicability to clinical testing for disease-associated genetic variants.

Menin and p53 have non-synergistic effects on tumorigenesis in mice

BACKGROUND

While it is now more than a decade since the first description of the gene mutation underlying the tumour predisposition syndrome multiple endocrine neoplasia type 1 (MEN1), the mechanism by which its protein product menin acts to prevent development of tumours is still poorly understood.

METHODS

We undertook a genetic experiment to assess whether menin synergises with p53. Mice carrying various combinations of Men1 and Trp53 mutations were generated then survival and pathology assessed.

RESULTS

While homozygous loss of Trp53 in mice resulted in early onset, aggressive tumours and profoundly reduced lifespan, heterozygous loss of either Trp53 or Men1 caused later onset disease, with a spectrum of tumours characteristic of each tumour suppressor gene. Loss of one copy of Men1 in animals also lacking both alleles of Trp53 did not exacerbate phenotype, based on survival, animal weight or sites of pathology, compared to Trp53 deletion alone. Dual heterozygous deletion of Men1 and Trp53 resulted in a small reduction in lifespan compared to the individual mutations, without new tumour sites. In the adrenal, we observed development of cortical tumours in dual heterozygous animals, as we have previously seen in Men1+/- animals, and there was loss of heterozygosity at the Men1 allele in these tumours. Median number of pathology observations per animal was increased in dual heterozygous animals compared with heterozygous loss of Trp53 alone.

CONCLUSIONS

Simultaneous heterozygous deletion of Men1 in animals with either heterozygous or homozygous deletion of Trp53 did not result in formation of tumours at any new sites, implying additive rather than synergistic effects of these pathways. Mice that were Men1+/- in addition to Trp53+/- had tumours in endocrine as well as other sites, implying that increase in total tumour burden, at sites typically associated with either Men1 or Trp53 loss, contributed to the slight decrease in survival in Men1+/-: Trp53+/- animals in comparison with their littermates.

Elevated Dnmt3a activity promotes polyposis in Apc(Min) mice by relaxing extracellular restraints on Wnt signaling

BACKGROUND & AIMS

Aberrant DNA methylation is a common early event in neoplasia, but it is unclear how this relates to dysregulation of DNA (cytosine-5) methyltransferases (Dnmts). Here we use knock-in transgenic mice to investigate the consequences of intestinal epithelium-specific overexpression of de novo Dnmt3a.

METHODS

A novel gene targeting strategy, based on the intestinal epithelium-specific, uniform expression of the A33 glycoprotein, is employed to restrict Dnmt3a overexpression in homozygous A33(Dnmt3a) mutant mice.

RESULTS

A33(Dnmt3a) mice infrequently develop spontaneous intestinal polyps. However, when genetically challenged, tumor multiplicity in A33(Dnmt3a);Apc(Min) compound mice is 3-fold higher than in Apc(Min) mice. Although we observe a requirement for spontaneous loss of heterozygosity of the adenomatous polyposis coli (Apc) gene to trigger tumorigenesis in Apc(Min) mice, lesions in A33(Dnmt3a);Apc(Min) mice frequently retain the wild-type Apc allele. However, epithelia from normal mucosa and polyps of A33(Dnmt3a);Apc(Min) mice show hypermethylation-mediated transcriptional silencing of the Wnt antagonists Sfrp5, and to a lesser extent, Sfrp1 and increased nuclear beta-catenin alongside activation of the Wnt-target gene Axin2/Conductin. Conversely, enforced Sfrp5 expression suppresses canonical Wnt-signaling more effectively in wild-type than in Apc(Min) cells.

CONCLUSIONS

Aberrant activation of the canonical Wnt pathway, either by mono-allelic Apc loss or transcriptional silencing of Sfrp5 is largely insufficient to promote polyposis, but epistatic interactions between these genetic and epigenetic events enables initiation and promotion of disease. This mechanism is likely to play a role in human colorectal cancer, because we also show that elevated DNMT3A expression coincides with repressed SFRP5 and enhanced AXIN2/CONDUCTIN expression in paired patient biopsies.

Pathology features in Bethesda guidelines predict colorectal cancer microsatellite instability: a population-based study

BACKGROUND & AIMS

The revised Bethesda guidelines for Lynch syndrome recommend microsatellite instability (MSI) testing all colorectal cancers in patients diagnosed before age 50 years and colorectal cancers diagnosed in patients between ages 50 and 59 years with particular pathology features. Our aim was to identify pathology and other features that independently predict high MSI (MSI-H).

METHODS

Archival tissue from 1098 population-based colorectal cancers diagnosed before age 60 years was tested for MSI. Pathology features, site, and age at diagnosis were obtained. Multiple logistic regression was performed to determine the predictive value of each feature, as measured by an odds ratio (OR), from which a scoring system (MsPath) was developed to estimate the probability a colorectal cancer is MSI-H.

RESULTS

Fifteen percent of tumors (162) were MSI-H. Independent predictors were tumor-infiltrating lymphocytes (OR, 9.1; 95% confidence interval [CI], 5.9-14.1), proximal subsite (OR, 4.7; 95% CI, 3.1-7.3), mucinous histology (OR, 2.8; 95% CI, 1.7-4.8), poor differentiation (OR, 1.9; 95% CI, 1.2-3.1), Crohn's-like reaction (OR, 1.9; 95% CI, 1.2-2.9), and diagnosis before age 50 years (OR, 1.9; 95% CI, 1.3-2.9). MsPath score >or=1.0 had a sensitivity of 93% and a specificity of 55% for MSI-H.

CONCLUSIONS

The probability an individual colorectal cancer is MSI-H is predicted well by the MsPath score. There is little value in testing for DNA mismatch repair loss in tumors, or for germline mismatch repair mutations, for colorectal cancers diagnosed in patients before age 60 years with an MSPath score <1 (approximately 50%). Pathology can identify almost all MSI-H colorectal cancers diagnosed before age 60 years.

Incorporation of somatic BRAF mutation testing into an algorithm for the investigation of hereditary non-polyposis colorectal cancer

Patients suspected on clinical grounds to have hereditary non-polyposis colorectal cancer (HNPCC) may be offered laboratory testing in order to confirm the diagnosis and to facilitate screening of pre-symptomatic family members. Tumours from an affected family member are usually pre-screened for microsatellite instability (MSI) and/or loss of immunohistochemical expression of mismatch repair (MMR) genes prior to germline MMR gene mutation testing. The efficiency of this triage process is compromised by the more frequent occurrence of sporadic colorectal cancer (CRC) showing high levels of MSI (MSI-H) due to epigenetic loss of MLH1 expression. Somatic BRAF mutations, most frequently V600E, have been described in a significant proportion of sporadic MSI-H CRC but not in HNPCC-associated cancers. BRAF mutation testing has therefore been proposed as a means to more definitively identify and exclude sporadic MSI-H CRC cases from germline MMR gene testing. However, the clinical validity and utility of this approach have not been previously evaluated in a familial cancer clinic setting. Testing for the V600E mutation was performed on MSI-H CRC samples from 68 individuals referred for laboratory investigation of suspected HNPCC. The V600E mutation was identified in 17 of 40 (42%) tumours showing loss of MLH1 protein expression by immunohistochemistry but in none of the 28 tumours that exhibited loss of MSH2 expression (P < 0.001). The assay was negative in all patients with an identified germline MMR gene mutation. Although biased by the fact that germline testing was not pursued beyond direct sequencing in many cases lacking a high clinical index of suspicion of HNPCC, BRAF V600E detection was therefore considered to be 100% specific and 48% sensitive in detecting sporadic MSI-H CRC amongst those cases showing loss of MLH1 protein expression, in a population of patients with MSI-H CRC and clinical features suggestive of HNPCC. Accordingly, we recommend the incorporation of BRAF V600E mutation testing into the laboratory algorithm for pre-screening patients with suspected HNPCC, whose CRCs show loss of expression of MLH1. In such tumours, the presence of a BRAF V600E mutation indicates the tumour is not related to HNPCC and that germline testing of MLH1 in that individual is not warranted. We also recommend that in families where the clinical suspicion of HNPCC is high, germline testing should not be performed on an individual whose CRC harbours a somatic BRAF mutation, as this may compromise identification of the familial mutation.

Matching patients with drugs: triumphs and challenges

The foundations of personalized medicine are built on the premise that laboratory tests can accurately predict the response of individual patients to a particular treatment. Herceptin® and the HercepTest®, which is used to select patients with human epidermal growth factor receptor (HER2)-positive breast cancer, are rightfully the jewels in the crown of this new treatment paradigm. Although over 8 years have past since their joint approval, there remain ongoing concerns about the quality of HER2 testing in community pathology laboratories. The development of predictive epidermal growth factor receptor (EGFR) tests for treatment with Tarceva®, Iressa® and Erbitux® has proven more difficult due to the complex biology of the target. It has also exposed some of the business challenges of co-developing both a drug and a companion diagnostic test. This article describes Genentech’s experience of developing predictive tests for HER2 and EGFR and highlights the need for close collaboration between all parties involved in incorporating predictive diagnostic tests into clinical trials and clinical practice.

KIT immunohistochemistry and mutation status in gastrointestinal stromal tumours (GISTs) evaluated for treatment with imatinib

AIMS

With the availability of effective but expensive treatment in the form of imatinib, accurate diagnosis of gastrointestinal stromal tumour (GIST) is extremely important. The aims of this study were: to describe the clinicopathological, immunohistochemical and molecular features of cases referred to a cancer centre with a possible diagnosis of GIST; to identify pitfalls in the performance and interpretation of KIT immunohistochemistry; to define the role of KIT mutation testing in making a diagnosis of GIST.

METHODS AND RESULTS

Morphological review, KIT immunohistochemistry and mutation testing were performed on all cases referred with a diagnosis of GIST or where the diagnosis was under serious consideration on the basis of KIT immunopositivity with a view to treating with imatinib. Thirty-seven cases met the inclusion criteria. Of these, 26 were classified as GIST and 11 as non-GIST. Most GISTs showed strong diffuse membranous, cytoplasmic or paranuclear KIT immunopositivity. Some non-GISTs demonstrated patchy cytoplasmic KIT immunopositivity related to the immunohistochemical protocol used in the external laboratory, which led to erroneous diagnoses of GIST in nine (24%) cases. KIT mutations involving exons 11 or 9 were identified in 22 (88%) GISTs tested and none of the non-GISTs.

CONCLUSIONS

An accurate diagnosis of GIST can be made on clinicopathological and immunohistochemical criteria without the need for mutational analysis in most cases, provided proper attention is paid to the immunohistochemical protocol used and, most importantly, control material. False-positive diagnoses of GIST potentially leading to inappropriate treatment with imatinib are more common than missed diagnoses.

Gastrointestinal stromal tumour treated with neoadjuvant imatinib

This report describes a case of unresectable primary gastrointestinal stromal tumour (GIST) treated with imatinib on a neoadjuvant basis, before subsequent successful surgical resection. After six months of imatinib, computed tomography and positron emission tomography imaging demonstrated a significant size reduction and complete metabolic response to treatment, rendering the tumour resectable. Mutational analysis showed an activating KIT mutation in exon 11. The pathological appearance of the resected tumour was heterogeneous with extensive necrosis, cystic and myxoid change, extensive hypocellularity, and patchy foci of residual viable tumour. The implications for this management option of radiological, pathological, and molecular assessment are discussed.

An expression-based site of origin diagnostic method designed for clinical application to cancer of unknown origin

Gene expression profiling offers a promising new technique for the diagnosis and prognosis of cancer. We have applied this technology to build a clinically robust site of origin classifier with the ultimate aim of applying it to determine the origin of cancer of unknown primary (CUP). A single cDNA microarray platform was used to profile 229 primary and metastatic tumors representing 14 tumor types and multiple histologic subtypes. This data set was subsequently used for training and validation of a support vector machine (SVM) classifier, demonstrating 89% accuracy using a 13-class model. Further, we show the translation of a five-class classifier to a quantitative PCR-based platform. Selecting 79 optimal gene markers, we generated a quantitative-PCR low-density array, allowing the assay of both fresh-frozen and formalin-fixed paraffin-embedded (FFPE) tissue. Data generated using both quantitative PCR and microarray were subsequently used to train and validate a cross-platform SVM model with high prediction accuracy. Finally, we applied our SVM classifiers to 13 cases of CUP. We show that the microarray SVM classifier was capable of making high confidence predictions in 11 of 13 cases. These predictions were supported by comprehensive review of the patients' clinical histories.

Plasma granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor levels in critical illness including sepsis and septic shock: relation to disease severity, multiple organ dysfunction, and mortality

OBJECTIVE

To define the circulating levels of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) during critical illness and to determine their relationship to the severity of illness as measured by the Acute Physiology and Chronic Health Evaluation (APACHE) II score, the development of multiple organ dysfunction, or mortality.

DESIGN

Prospective cohort study.

SETTING

University hospital intensive care unit.

PATIENTS

A total of 82 critically ill adult patients in four clinically defined groups, namely septic shock (n = 29), sepsis without shock (n = 17), shock without sepsis (n = 22), and nonseptic, nonshock controls (n = 14).

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

During day 1 of septic shock, peak plasma levels of G-CSF, interleukin (IL)-6, and leukemia inhibitory factor (LIF), but not GM-CSF, were greater than in sepsis or shock alone (p < .001), and were correlated among themselves (rs = 0.44-0.77; p < .02) and with the APACHE II score (rs = 0.25-0.40; p = .03 to .18). G-CSF, IL-6, and UF, and sepsis, shock, septic shock, and APACHE II scores were strongly associated with organ dysfunction or 5-day mortality by univariate analysis. However, multiple logistic regression analysis showed that only septic shock remained significantly associated with organ dysfunction and only APACHE II scores and shock with 5-day mortality. Similarly, peak G-CSF, IL-6, and LIF were poorly predictive of 30-day mortality.

CONCLUSIONS

Plasma levels of G-CSF, IL-6, and LIF are greatly elevated in critical illness, including septic shock, and are correlated with one another and with the severity of illness. However, they are not independently predictive of mortality, or the development of multiple organ dysfunction. GM-CSF was rarely elevated, suggesting different roles for G-CSF and GM-CSF in human septic shock.

Continuous plasmafiltration in sepsis syndrome. Plasmafiltration in Sepsis Study Group

OBJECTIVE

To assess the effect of plasmafiltration (PF) on biochemical markers of inflammation, cytokines, organ dysfunction, and 14-day mortality in human sepsis.

DESIGN

Multicenter, prospective, randomized, controlled clinical trial.

SETTING

Seven university-affiliated intensive care units.

PATIENTS

Thirty patients (22 adults, eight children) with new (<24 hrs) clinical evidence of infection and sepsis syndrome were enrolled. Fourteen of 30 (nine adults, five children) were randomized to PF.

INTERVENTIONS

All patients received protocol-driven supportive intensive care, and those randomized to PF received continuous plasma exchange for 34 hrs using a hollow-fiber plasma filter.

MEASUREMENTS AND MAIN RESULTS

Illness severity and risk of death were calculated with the Pediatric Risk of Mortality (children) and the Acute Physiology and Chronic Health Evaluation II (adults) scales. Plasma samples (0, 6, 24, and 48 hrs) were assayed for acute-phase proteins (albumin, globulin, C-reactive protein, alpha1-antitrypsin, haptoglobin), inflammatory mediators (complement fragment C3, thromboxane B2), and cytokines (interleukin-6, granulocyte colony-stimulating factor, leukemia inhibitory factor). Sieving coefficients were estimated from filtrate concentrations at 3 hrs. The two groups were matched for incidence of septic shock (13 of 14 vs. 11 of 16), refractory shock (three of 14 vs. six of 16), bacteremia (six of 14 vs. five of 16), severity of illness, and calculated risk of death (0.68 vs. 0.64). There was no difference in mortality. Eight of 14 PF patients (57%) and eight of 16 controls (50%) survived for 14 days (p = .73, Fisher's exact test). Multiple logistic regression revealed age (odds ratio, 16.4:1; 95% confidence interval, 2.12-infinity) and shock (10.6:1; 1.32-infinity) as significant predictors of death; plasmafiltration was associated with a nonsignificant reduction in the risk of death (odds ratio, 1.78:1; 95% confidence interval, 0.20-18.1). The mean (SD) number of organs failing in the first 7 days in the PF group was 2.57 (0.94) vs. 2.94 (0.85) in controls (p = .37, Mann-Whitney U test). Both groups had similarly elevated plasma concentrations of all inflammatory mediators except complement fragment C3 at study entry. Leukemia inhibitory factor was detectable in four patients only. PF did not influence mean concentrations of interleukin-6, granulocyte colony-stimulating factor, thromboxane B2, total white cell count, neutrophil count, or platelet count, but it was associated with significant reductions of alpha1-antitrypsin, haptoglobin, C-reactive protein, and complement fragment C3 in the first 6 hrs (p < .05). The sieving coefficients for all inflammatory mediators approached unity.

CONCLUSIONS

PF caused a significant attenuation of the acute-phase response in sepsis. There was no significant difference in mortality, but there was a trend toward fewer organs failing in the PF group that suggests that this procedure might be beneficial.

Differential alterations in plasma colony-stimulating factor concentrations in meningococcaemia

To determine whether circulating levels of any of the colony-stimulating factors (CSF) might contribute to the host response in severe sepsis, plasma concentrations of granulocyte CSF (G-CSF), granulocyte-macrophage CSF (GM-CSF), and macrophage CSF (M-CSF) were measured by immunoassays in 20 subjects with meningococcaemia, a bloodstream infection caused by Neisseria meningitidis, that has proven to be a valuable model to study the responses of other inflammatory mediators during sepsis and septic shock in humans. Plasma G-CSF concentrations were transiently elevated in most subjects during the early phase of meningococcaemia, and were higher in subjects with septic shock (mean +/- s.d. = 165 +/- 142 ng/ml, n = 9) compared with those who remained normotensive (mean +/- s.d. = 7 +/- 2 ng/ml, n = 10) (P < 0.05). Peak plasma G-CSF concentrations > 10 ng/ml were associated with the development of septic shock (P < 0.01), disseminated intravascular coagulation (P < 0.01), fulminant infection (P < 0.05), and a fatal outcome (P < 0.01). Plasma GM-CSF concentrations > 1 ng/ml were briefly present in subjects with life-threatening septic shock (1-15 ng/ml, n = 5), and were strongly associated with fulminant meningococcaemia (P < 0.01). Plasma M-CSF concentrations were marginally elevated in all subjects, but were not associated with complications related to or arising from sepsis-induced organ injury. This study demonstrates that plasma levels of G-CSF, GM-CSF and M-CSF show very different responses during meningococcaemia, changes which presumably reflect the different roles played by these mediators in sepsis and, potentially, in septic shock.

Leukemia inhibitory factor protects against experimental lethal Escherichia coli septic shock in mice

Leukemia inhibitory factor (LIF) has recently been associated with septic shock in humans. In this study we sought to determine, in mice, the role of LIF in septic shock. During sublethal endotoxemia, serum LIF levels, as determined by radio-receptor competition assay, peaked at 2 h and were low (3 ng/ml), whereas in lethal Escherichia coli septic shock serum LIF levels rose progressively (> 30 ng/ml) in the premorbid phase coincident with the development of tissue injury. Single i.v. injections of high doses (up to 50 micrograms per mouse) of recombinant murine LIF had no obvious acute detrimental effects, whereas continued i.p. administration (30 micrograms per mouse per day) for 3-4 days induced a fatal catabolic state without evidence of preceding hemodynamic collapse or shock. Simultaneous or subsequent administration of high doses of LIF had no effect on mortality from sublethal and lethal E. coli septic shock, whereas prior administration conferred significant protection against lethality (P << 0.001 by log-rank test), an effect that was dose and interval dependent. This protective effect resembled endotoxin tolerance and was characterized by suppression of E. coli-induced serum tumor necrosis factor concentration (P < 0.05), reduction in the number of viable bacteria (P < 0.05), and prevention of sepsis-induced tissue injury. These observations suggest that systemic LIF production is part of the host response to both endotoxin and sepsis-induced tissue injury.

Circulating leukemia inhibitory factor levels correlate with disease severity in meningococcemia

Circulating concentrations of the proinflammatory cytokine leukemia inhibitory factor (LIF) were prospectively determined by radioreceptor competition assay (sensitivity, 1 ng/mL) in 33 subjects with meningococcemia. LIF was detected in the plasma of 13 subjects and was associated with development of septic shock (P < .01), disseminated intravascular coagulation (P < .05), multiorgan failure (P < .05), and death (P < .01). Plasma LIF concentrations were highest (1-1772 ng/mL) at hospital admission and became undetectable within 36 h, and the peak levels correlated inversely with systolic blood pressure (r, -.70, P < .001), peripheral blood leukocyte count (r, -.58, P < .01), and prodromal interval (r, -.60, P < .001). Plasma LIF concentrations > 400 ng/mL were present only in subjects with fatal fulminant infection. LIF concentrations in plasma collected within 12 h of hospital admission correlated with disease severity in patients with meningococcemia. It is likely that LIF participates in the host response to infection, and it may contribute to the pathogenesis of septic shock.

Leukemia inhibitory factor: association with intraamniotic infection

OBJECTIVE

Our purpose was to investigate whether leukemia inhibitory factor is associated with intraamniotic infection.

STUDY DESIGN

A comparative clinical study of amniotic fluid leukemia inhibitory factor concentrations was performed.

RESULTS

Leukemia inhibitory factor was undetectable (< 1 ng/ml) by radioreceptor assay during normal pregnancy at midtrimester and at term. Among women in labor those with intraamniotic infection had higher leukemia factor concentrations than those without infection before term (p < 0.001) and at term (p < 0.005). The leukemia inhibitory factor concentrations correlated with the amniotic fluid white blood cell counts (r = 0.47) (p < 0.001). In cultured human gestational tissue explants, leukemia inhibitory factor release was significantly enhanced by endotoxin, interleukin-1 alpha, and tumor necrosis factor-alpha however, leukemia inhibitory factor did not enhance the release of prostaglandin E2 by these tissues.

CONCLUSIONS

Amniotic fluid leukemia inhibitory factor concentrations were elevated during intraamniotic infection and gestational tissues released leukemia inhibitory factor in response to bacterial products and inflammatory mediators.

Increased levels of leukemia inhibitory factor in synovial fluid from patients with rheumatoid arthritis and other inflammatory arthritides

OBJECTIVE

To examine synovial fluid (SF) from patients with arthritis, for the presence of the cytokine leukemia inhibitory factor (LIF).

METHODS

SF from 152 subjects was examined for LIF, using a radioreceptor competition assay.

RESULTS

LIF was present at concentrations of 1-43 ng/ml in the SF of 23% of patients with rheumatoid arthritis (RA) or other inflammatory or infectious arthritides but in only 1 of 29 patients with osteoarthritis (P < 0.01). In the RA patients, the SF LIF concentration correlated significantly with the peripheral blood white blood cell count (WBC) (P < 0.05) and the SF WBC count (P < 0.01), but not with other clinical or radiologic parameters of disease activity or progression.

CONCLUSION

LIF is implicated as a potential mediator of the local or systemic inflammatory response or the joint destruction seen in inflammatory arthritis.

Induction of leukemia inhibitory factor in human synovial fibroblasts by IL-1 and tumor necrosis factor-alpha

The cytokines, IL-1 alpha and TNF-alpha, induced a dose-dependent production of leukemia inhibitory factor (LIF) in cultured human synovial fibroblast-like cells, as measured by a radioreceptor competition assay. Significant levels of LIF were first detected in cell supernatants between 2 and 4 h after cytokine addition. Increases were also observed in LIF mRNA steady-state expression. Evidence is presented for down-regulation of the IL-1-induced LIF activity by an endogenous cyclo-oxygenase product(s); the glucocorticoid, dexamethasone, lowered the IL-1-induced LIF activity and mRNA expression. A synergistic effect was noted between the actions of IL-1 alpha and TNF-alpha, and between IL-1 and transforming growth factor-beta. IFN-gamma could not induce LIF formation in the synovial cells but inhibited the stimulatory effect of IL-1. These results suggest that cytokine-stimulated synovial fibroblasts may be a major source of intraarticular LIF production in the joints of patients with inflammatory arthritis. Synoviocyte-derived LIF may activate monocyte/macrophages in the lesions and may contribute to the bone changes and certain systemic manifestations in patients with inflammatory joint disease.

Induction of leukemia inhibitory factor in human synovial fibroblasts by IL-1 and tumor necrosis factor-alpha

The cytokines, IL-1 alpha and TNF-alpha, induced a dose-dependent production of leukemia inhibitory factor (LIF) in cultured human synovial fibroblast-like cells, as measured by a radioreceptor competition assay. Significant levels of LIF were first detected in cell supernatants between 2 and 4 h after cytokine addition. Increases were also observed in LIF mRNA steady-state expression. Evidence is presented for down-regulation of the IL-1-induced LIF activity by an endogenous cyclo-oxygenase product(s); the glucocorticoid, dexamethasone, lowered the IL-1-induced LIF activity and mRNA expression. A synergistic effect was noted between the actions of IL-1 alpha and TNF-alpha, and between IL-1 and transforming growth factor-beta. IFN-gamma could not induce LIF formation in the synovial cells but inhibited the stimulatory effect of IL-1. These results suggest that cytokine-stimulated synovial fibroblasts may be a major source of intraarticular LIF production in the joints of patients with inflammatory arthritis. Synoviocyte-derived LIF may activate monocyte/macrophages in the lesions and may contribute to the bone changes and certain systemic manifestations in patients with inflammatory joint disease.

Prostatic embryonal rhabdomyosarcoma in adults. A clinicopathologic review

Embryonal rhabdomyosarcoma of the prostate is a rare, highly malignant tumor that occurs predominantly in male infants and children, in whom it is the most common prostatic sarcoma. Six cases occurring in adults have been published, and the authors report three additional cases. The natural history is characterized by rapid growth, with the typical formation of large pelvic or abdominal masses, often leading renal failure due to bilateral ureteric obstruction. The tumor eventually disseminates widely, mainly to the lungs, bone, liver, and serosal surfaces, and unlike most other sarcomas, regional lymph node metastases are common. Combined modality therapy has resulted in marked improvement in survival rates and reduced surgical morbidity for children with these tumors. However, in adults the prognosis remains poor, with all patients dying of disseminated disease within 16 months of histologic diagnosis (mean survival, 8 months).

Clearance and fate of leukemia-inhibitory factor (LIF) after injection into mice

Leukemia-inhibitory factor (LIF) elicits effects on a broad range of cell types, including cells of the monocytic and megakaryocytic series, embryonal stem cells, hepatocytes, adipocytes, and osteoblasts. Native and recombinant LIF, injected intravenously into adult mice, had an initial half-life of 6-8 min and a more prolonged second clearance phase. Clearance of 125I-LIF from the circulation was paralleled by a rapid accumulation in the kidneys, liver, lungs, and spleen and a more gradual accumulation in the thyroid gland. Labeling of the renal glomerular tufts, parenchymal hepatocytes, splenic red pulp, alveolar pneumocytes, and thyroid follicular cells as well as of megakaryocytes and osteoblasts in the bone cavities, placental trophoblasts, and cells of the choroid plexus was demonstrable autoradiographically. The appearance of a large amount of nonprecipitable 125I in the urine suggested that the kidneys were the major route of LIF clearance from the body.

Rare earth deposits in a deceased movie projectionist. A new case of rare earth pneumoconiosis?

The subject described in this case report, a movie projectionist, had approximately 25 years of occupational exposure to carbon arc lamp fumes. The carbon arc deposits were visible in histological sections as small granules within macrophages of the tracheobronchial lymph nodes and hepatic Kupffer's cells. Electron microprobe analysis by energy dispersive analysis of x-rays showed the granules to be composed of the rare earth elements cerium, lanthanum and neodymium, which are the major constituents of carbon arc rods. Tissue concentrations, as determined by inductively coupled plasma spectroscopy, were approximately 250-2000 times those of unexposed controls, and there was evidence of their redistribution throughout the reticuloendothelial system. There were no respiratory symptoms, or radiographic or histological pulmonary changes attributable to the progressive accumulation of the rare earth elements, and as such the patient cannot be considered to have suffered from pneumoconiosis. Twenty-one published cases of rare earth pneumoconiosis, mainly in photoengravers exposed to carbon arc fumes, are reviewed and suggest that rare earth oxides are not innocuous dusts. With the increasingly widespread use of rare earth elements there is a likelhood that further occupational groups may have significant but unrecognised exposure.

'Corkscrew-like' bacteria associated with gastritis

Gastric spiral bacteria morphologically unlike Campylobacter pylori have recently been described in patients with gastritis. We report an additional case. These organisms are as yet unnamed, remain uncultured and are morphologically similar to organisms present in the gastric mucosa of various mammalian species. Their possible role in the pathogenesis of gastritis is discussed.

Bladder granulomata after bladder surgery

Bladder granulomata were found in 17 (3%) of 539 patients who had bladder biopsy or resection. The finding of granulomata in 13.6% of patients who had at least two surgical procedures, but never in the first biopsy specimen of any patient was highly significant statistically (P much less than 0.001). The occurrence of granulomata exclusively in patients with bladder carcinoma was related to the significantly greater number of biopsies performed in these patients and not to carcinoma, per se. There were two types of granulomata: necrotizing, palisading granulomata (NPG) resembling rheumatoid granulomata; and foreign-body-type granulomata (FBG). They often occurred together in the same specimen, and transitions from FBG to NPG were evident histologically. The granulomata apparently healed by fibrous scarring. Energy-dispersive analysis of x-rays (EDAX) did not reveal any inorganic foreign material, but showed sulphur in some granulomata, possibly released from necrotic stroma and urothelium. Clinical and morphologic evidence is presented indicating that the granulomata arose as a local reaction to tissue necrosis caused by surgery and/or cautery.