Tumor genomic, transcriptomic, and immune profiling characterizes differential response to first-line platinum chemotherapy in high grade serous ovarian cancer

Background

In high grade serous ovarian cancer (HGSOC), there is a spectrum of sensitivity to first line platinum‐based chemotherapy. This study molecularly characterizes HGSOC patients from two distinct groups of chemotherapy responders (good vs. poor).

Methods

Following primary debulking surgery and intravenous carboplatin/paclitaxel, women with stage III–IV HGSOC were grouped by response. Patients in the good response (GR) and poor response (PR) groups respectively had a progression‐free intervals (PFI) of ≥12 and ≤6 months. Analysis of surgical specimens interrogated genomic and immunologic features using whole exome sequencing. RNA‐sequencing detected gene expression outliers and inference of immune infiltrate, with validation by targeted NanoString arrays. PD‐L1 expression was scored by immunohistochemistry (IHC).

Results

A total of 39 patient samples were analyzed (GR = 20; PR = 19). Median PFI for GR and PR patient cohorts was 32 and 3 months, respectively. GR tumors were enriched for loss‐of‐function BRCA2 mutations and had a significantly higher nonsynonymous mutation rate compared to PR tumors (p = 0.001). Samples from the PR cohort were characterized by mutations in MGA and RAD51B and trended towards a greater rate of amplification of PIK3CA, MECOM, and ATR in comparison to GR tumors. Gene expression analysis by NanoString correlated increased PARP4 with PR and increased PD‐L1 and EMSY with GR. There was greater tumor immune cell infiltration and higher immune cell PD‐L1 protein expression in the GR group.

Conclusions

Our research demonstrates that tumors from HGSOC patients responding poorly to first line chemotherapy have a distinct molecular profile characterized by actionable drug targets including PARP4.

Proliferation Tumour Marker Network (PTM-NET) for the identification of tumour region in Ki67 stained breast cancer whole slide images

Uncontrolled proliferation is a hallmark of cancer and can be assessed by labelling breast tissue using immunohistochemistry for Ki67, a protein associated with cell proliferation. Accurate measurement of Ki67-positive tumour nuclei is of critical importance, but requires annotation of the tumour regions by a pathologist. This manual annotation process is highly subjective, time-consuming and subject to inter- and intra-annotator experience. To address this challenge, we have developed Proliferation Tumour Marker Network (PTM-NET), a deep learning model that objectively annotates the tumour regions in Ki67-labelled breast cancer digital pathology images using a convolution neural network. Our custom designed deep learning model was trained on 45 immunohistochemical Ki67-labelled whole slide images to classify tumour and non-tumour regions and was validated on 45 whole slide images from two different sources that were stained using different protocols. Our results show a Dice coefficient of 0.74, positive predictive value of 70% and negative predictive value of 88.3% against the manual ground truth annotation for the combined dataset. There were minimal differences between the images from different sources and the model was further tested in oestrogen receptor and progesterone receptor-labelled images. Finally, using an extension of the model, we could identify possible hotspot regions of high proliferation within the tumour. In the future, this approach could be useful in identifying tumour regions in biopsy samples and tissue microarray images.

RAD51 foci as a functional biomarker of homologous recombination repair and PARP inhibitor resistance in germline BRCA-mutated breast cancer

Background

BRCA1 and BRCA2 (BRCA1/2)-deficient tumors display impaired homologous recombination repair (HRR) and enhanced sensitivity to DNA damaging agents or to poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi). Their efficacy in germline BRCA1/2 (gBRCA1/2)-mutated metastatic breast cancers has been recently confirmed in clinical trials. Numerous mechanisms of PARPi resistance have been described, whose clinical relevance in gBRCA-mutated breast cancer is unknown. This highlights the need to identify functional biomarkers to better predict PARPi sensitivity.

Patients and methods

We investigated the in vivo mechanisms of PARPi resistance in gBRCA1 patient-derived tumor xenografts (PDXs) exhibiting differential response to PARPi. Analysis included exome sequencing and immunostaining of DNA damage response proteins to functionally evaluate HRR. Findings were validated in a retrospective sample set from gBRCA1/2-cancer patients treated with PARPi.

Results

RAD51 nuclear foci, a surrogate marker of HRR functionality, were the only common feature in PDX and patient samples with primary or acquired PARPi resistance. Consistently, low RAD51 was associated with objective response to PARPi. Evaluation of the RAD51 biomarker in untreated tumors was feasible due to endogenous DNA damage. In PARPi-resistant gBRCA1 PDXs, genetic analysis found no in-frame secondary mutations, but BRCA1 hypomorphic proteins in 60% of the models, TP53BP1-loss in 20% and RAD51-amplification in one sample, none mutually exclusive. Conversely, one of three PARPi-resistant gBRCA2 tumors displayed BRCA2 restoration by exome sequencing. In PDXs, PARPi resistance could be reverted upon combination of a PARPi with an ataxia-telangiectasia mutated (ATM) inhibitor.

Conclusion

Detection of RAD51 foci in gBRCA tumors correlates with PARPi resistance regardless of the underlying mechanism restoring HRR function. This is a promising biomarker to be used in the clinic to better select patients for PARPi therapy. Our study also supports the clinical development of PARPi combinations such as those with ATM inhibitors.

Appraising the relevance of DNA copy number loss and gain in prostate cancer using whole genome DNA sequence data

A variety of models have been proposed to explain regions of recurrent somatic copy number alteration (SCNA) in human cancer. Our study employs Whole Genome DNA Sequence (WGS) data from tumor samples (n = 103) to comprehensively assess the role of the Knudson two hit genetic model in SCNA generation in prostate cancer. 64 recurrent regions of loss and gain were detected, of which 28 were novel, including regions of loss with more than 15% frequency at Chr4p15.2-p15.1 (15.53%), Chr6q27 (16.50%) and Chr18q12.3 (17.48%). Comprehensive mutation screens of genes, lincRNA encoding sequences, control regions and conserved domains within SCNAs demonstrated that a two-hit genetic model was supported in only a minor proportion of recurrent SCNA losses examined (15/40). We found that recurrent breakpoints and regions of inversion often occur within Knudson model SCNAs, leading to the identification of ZNF292 as a target gene for the deletion at 6q14.3-q15 and NKX3.1 as a two-hit target at 8p21.3-p21.2. The importance of alterations of lincRNA sequences was illustrated by the identification of a novel mutational hotspot at the KCCAT42, FENDRR, CAT1886 and STCAT2 loci at the 16q23.1-q24.3 loss. Our data confirm that the burden of SCNAs is predictive of biochemical recurrence, define nine individual regions that are associated with relapse, and highlight the possible importance of ion channel and G-protein coupled-receptor (GPCR) pathways in cancer development. We concluded that a two-hit genetic model accounts for about one third of SCNA indicating that mechanisms, such haploinsufficiency and epigenetic inactivation, account for the remaining SCNA losses.

Abstract 150: Identification of determinants of sensitivity to AKT inhibition using breast cancer (BC) patient-derived tumor xenografts (PDX)

The antitumor activity of AKT inhibitors is being investigated for the treatment of BC with activation of the PI3K/AKT pathway. Putative predictive biomarkers that are being tested in ongoing trials are PTEN loss/mutation (mut) (around 40% of triple negative BC) and AKT1 mutation (4-5% ER+/HER2- BC). The BEECH trial is evaluating the activity of the pan-AKT1/2/3 inhibitor (AKTi) AZD5363 in combination with the antimicrotubule agent paclitaxel in HER2-negative (HER2-) metastatic BC. We aimed to identify response biomarkers to the single agent AKTi and its degree of synergy in combination with paclitaxel, using HER2- patient-derived tumor xenografts (PDX).

Fifteen PDX have been established from BC patients receiving standard treatment at our Hospital, as well as from those participating in the BEECH trial, when sample was available, by implanting their tumor biopsies at baseline, on-treatment and at progression. The antitumor activity of AZD5363 as single agent and in combination with paclitaxel has been measured in these PDX. Genotyping and protein levels have been analyzed by exome sequencing, capture-based sequencing, Western blot and immunohistochemistry (IHC).

AZD5363 monotherapy results in disease stabilization or tumor regression in 3 out of 15 PDX (2/9 ER-/HER2- and 1/6 ER+/HER2-). We found a positive association between high levels of pAKT S473 by Western blot and antitumor response. Interestingly, the two ER-/HER2- responding PDX harbor a PTEN frameshift mutation or gene loss concomitant with an activating mutation within the PI3K pathway (PIK3CA or PIK3R1). The ER+/HER2- PDX responder harbors an AKT1-p.E17K mutation. AZD5363 plus paclitaxel, at a clinically relevant dose, results in disease stabilization in 2/11 PDX that progress to either single agent (1/7 ER-/HER2- and 1/4 ER+/HER2-); the latter PDX being derived from the baseline tumor biopsy of a BEECH trial patient who benefited from this combination for one year.

Altogether these results suggest that double-altering events in the PI3K pathway, including PTEN loss/mut and a second PI3K-pathway alteration in ER-/HER2- tumors, or AKT1-p.E17K in ER+/HER2- tumors, and consequent high pAkt S473 levels could be associated with intrinsic sensitivity to AKT inhibition. The predictive value of these alterations as determinants of response to AKTi deserves further investigation.

Citation Format: Albert Gris-Oliver, Mafalda Oliveira, Marta Guzman, Olga Rodríguez, Judit Grueso, Maurizio Scaltriti, William J. Howat, J Carl Barrett, Javier Cortés, José Baselga, Gaia Schiavon, Barry R. Davies, Cristina Saura, Violeta Serra. Identification of determinants of sensitivity to AKT inhibition using breast cancer (BC) patient-derived tumor xenografts (PDX) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 150. doi:10.1158/1538-7445.AM2017-150

Rapid Imaging of Tumor Cell Death In Vivo Using the C2A Domain of Synaptotagmin-I

Cell death is an important target for imaging the early response of tumors to treatment. We describe here the validation of a phosphatidylserine-binding agent for detecting tumor cell death in vivo based on the C2A domain of synaptotagmin-I. Methods: The capability of near-infrared fluorophore-labeled and 99mTc- and 111In-labeled derivatives of C2Am for imaging tumor cell death, using planar near-infrared fluorescence imaging and SPECT, respectively, was evaluated in implanted and genetically engineered mouse models of lymphoma and in a human colorectal xenograft. Results: The fluorophore-labeled C2Am derivative showed predominantly renal clearance and high specificity and sensitivity for detecting low levels of tumor cell death (2%-5%). There was a significant correlation (R > 0.9, P < 0.05) between fluorescently labeled C2Am binding and histologic markers of cell death, including cleaved caspase-3, whereas there was no such correlation with a site-directed mutant of C2Am (iC2Am) that does not bind phosphatidylserine. 99mTc-C2Am and 111In-C2Am also showed favorable biodistribution profiles, with predominantly renal clearance and low nonspecific retention in the liver and spleen at 24 h after probe administration. 99mTc-C2Am and 111In-C2Am generated tumor-to-muscle ratios in drug-treated tumors of 4.3× and 2.2×, respectively, at 2 h and 7.3× and 4.1×, respectively, at 24 h after administration. Conclusion: Given the favorable biodistribution profile of 99mTc- and 111In-labeled C2Am, and their ability to produce rapid and cell death-specific image contrast, these agents have potential for clinical translation.

Crowdsourcing for translational research: analysis of biomarker expression using cancer microarrays

BACKGROUND

Academic pathology suffers from an acute and growing lack of workforce resource. This especially impacts on translational elements of clinical trials, which can require detailed analysis of thousands of tissue samples. We tested whether crowdsourcing - enlisting help from the public - is a sufficiently accurate method to score such samples.

METHODS

We developed a novel online interface to train and test lay participants on cancer detection and immunohistochemistry scoring in tissue microarrays. Lay participants initially performed cancer detection on lung cancer images stained for CD8, and we measured how extending a basic tutorial by annotated example images and feedback-based training affected cancer detection accuracy. We then applied this tutorial to additional cancer types and immunohistochemistry markers - bladder/ki67, lung/EGFR, and oesophageal/CD8 - to establish accuracy compared with experts. Using this optimised tutorial, we then tested lay participants' accuracy on immunohistochemistry scoring of lung/EGFR and bladder/p53 samples.

RESULTS

We observed that for cancer detection, annotated example images and feedback-based training both improved accuracy compared with a basic tutorial only. Using this optimised tutorial, we demonstrate highly accurate (>0.90 area under curve) detection of cancer in samples stained with nuclear, cytoplasmic and membrane cell markers. We also observed high Spearman correlations between lay participants and experts for immunohistochemistry scoring (0.91 (0.78, 0.96) and 0.97 (0.91, 0.99) for lung/EGFR and bladder/p53 samples, respectively).

CONCLUSIONS

These results establish crowdsourcing as a promising method to screen large data sets for biomarkers in cancer pathology research across a range of cancers and immunohistochemical stains.

High-throughput automated scoring of Ki67 in breast cancer tissue microarrays from the Breast Cancer Association Consortium

Automated methods are needed to facilitate high-throughput and reproducible scoring of Ki67 and other markers in breast cancer tissue microarrays (TMAs) in large-scale studies. To address this need, we developed an automated protocol for Ki67 scoring and evaluated its performance in studies from the Breast Cancer Association Consortium. We utilized 166 TMAs containing 16,953 tumour cores representing 9,059 breast cancer cases, from 13 studies, with information on other clinical and pathological characteristics. TMAs were stained for Ki67 using standard immunohistochemical procedures, and scanned and digitized using the Ariol system. An automated algorithm was developed for the scoring of Ki67, and scores were compared to computer assisted visual (CAV) scores in a subset of 15 TMAs in a training set. We also assessed the correlation between automated Ki67 scores and other clinical and pathological characteristics. Overall, we observed good discriminatory accuracy (AUC = 85%) and good agreement (kappa = 0.64) between the automated and CAV scoring methods in the training set. The performance of the automated method varied by TMA (kappa range= 0.37-0.87) and study (kappa range = 0.39-0.69). The automated method performed better in satisfactory cores (kappa = 0.68) than suboptimal (kappa = 0.51) cores (p-value for comparison = 0.005); and among cores with higher total nuclei counted by the machine (4,000-4,500 cells: kappa = 0.78) than those with lower counts (50-500 cells: kappa = 0.41; p-value = 0.010). Among the 9,059 cases in this study, the correlations between automated Ki67 and clinical and pathological characteristics were found to be in the expected directions. Our findings indicate that automated scoring of Ki67 can be an efficient method to obtain good quality data across large numbers of TMAs from multicentre studies. However, robust algorithm development and rigorous pre- and post-analytical quality control procedures are necessary in order to ensure satisfactory performance.

Detection of colorectal dysplasia using fluorescently labelled lectins

Colorectal cancer screening using conventional colonoscopy lacks molecular information and can miss dysplastic lesions. We tested here the ability of fluorescently labelled lectins to distinguish dysplasia from normal tissue when sprayed on to the luminal surface epithelium of freshly resected colon tissue from the Apc(min) mouse and when applied to fixed human colorectal tissue sections. Wheat germ agglutinin (WGA) showed significantly decreased binding to adenomas in the mouse tissue and in sections of human colon from 47 patients. Changes in WGA binding to the human surface epithelium allowed regions containing normal epithelium (NE) or hyperplastic polyps (HP) to be distinguished from regions containing low-grade dysplasia (LGD), high-grade dysplasia (HGD) or carcinoma (C), with 81% sensitivity, 87% specificity and 93% positive predictive value (PPV). Helix pomatia agglutinin (HGA) distinguished epithelial regions containing NE from regions containing HP, LGD, HGD or C, with 89% sensitivity, 87% specificity and 97% PPV. The decreased binding of WGA and HPA to the luminal surface epithelium in human dysplasia suggests that these lectins may enable more sensitive detection of disease in the clinic using fluorescence colonoscopy.

An Examination of the Association between FOXA1 Staining Level and Biochemical Recurrence following Salvage Radiation Therapy for Recurrent Prostate Cancer

BACKGROUND

Standardly collected clinical and pathological patient information has demonstrated only moderate ability to predict risk of biochemical recurrence (BCR) of prostate cancer in men undergoing salvage radiation therapy (SRT) for a rising PSA after radical prostatectomy (RP). Although elevated FOXA1 staining has been associated with poor patient outcomes following RP, it has not been studied in the specific setting of SRT after RP. The aim of this study was to evaluate the association between FOXA1 staining level and BCR after SRT for recurrent prostate cancer.

METHODS

A total of 141 men who underwent SRT at our institution were included. FOXA1 staining levels in primary tumor samples were detected using immunohistochemistry. FOXA1 staining percentage and intensity were measured and multiplied together to obtain a FOXA1 H-score (range 0-12) which was our primary staining measure. P-values ≤ 0.0056 were considered as statistically significant after applying a Bonferroni correction for multiple comparisons.

RESULTS

There was not a significant association between FOXA1 H-score and risk of BCR when considering H-score as an ordinal variable or as a categorical variable (all P ≥ 0.090). Similarly, no significant associations with BCR were observed for FOXA1 staining percentage or staining intensity (all P ≥ 0.14).

CONCLUSIONS

FOXA1 staining level does not appear to have a major impact on risk of BCR after SRT.

Hypoxia-induced nitric oxide production and tumour perfusion is inhibited by pegylated arginine deiminase (ADI-PEG20)

The hypoxic tumour microenvironment represents an aggressive, therapy-resistant compartment. As arginine is required for specific hypoxia-induced processes, we hypothesised that arginine-deprivation therapy may be useful in targeting hypoxic cancer cells. We explored the effects of the arginine-degrading agent ADI-PEG20 on hypoxia-inducible factor (HIF) activation, the hypoxia-induced nitric oxide (NO) pathway and proliferation using HCT116 and UMUC3 cells and xenografts. The latter lack argininosuccinate synthetase (ASS1) making them auxotrophic for arginine. In HCT116 cells, ADI-PEG20 inhibited hypoxic-activation of HIF-1α and HIF-2α, leading to decreased inducible-nitric oxide synthase (iNOS), NO-production, and VEGF. Interestingly, combining hypoxia and ADI-PEG20 synergistically inhibited ASS1. ADI-PEG20 inhibited mTORC1 and activated the unfolded protein response providing a mechanism for inhibition of HIF and ASS1. ADI-PEG20 inhibited tumour growth, impaired hypoxia-associated NO-production, and decreased vascular perfusion. Expression of HIF-1α/HIF-2α/iNOS and VEGF were reduced, despite an increased hypoxic tumour fraction. Similar effects were observed in UMUC3 xenografts. In summary, ADI-PEG20 inhibits HIF-activated processes in two tumour models with widely different arginine biology. Thus, ADI-PEG20 may be useful in the clinic to target therapy-resistant hypoxic cells in ASS1-proficient tumours and ASS1-deficient tumours.

MRI with hyperpolarised [1-13C]pyruvate detects advanced pancreatic preneoplasia prior to invasive disease in a mouse model

OBJECTIVES

Pancreatic cancer (PCa) is treatable by surgery when detected at an early stage. Non-invasive imaging methods able to detect both established tumours and their precursor lesions are needed to select patients for surgery. We investigated here whether pancreatic preneoplasia could be detected prior to the development of invasive cancers in genetically engineered mouse models of PCa using metabolic imaging.

DESIGN

The concentrations of alanine and lactate and the activities of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) were measured in extracts prepared from the pancreas of animals at different stages of disease progression; from pancreatitis, through tissue with predominantly low-grade and then high-grade pancreatic intraepithelial neoplasia and then tumour. (13)C magnetic resonance spectroscopic imaging ((13)C-MRSI) was used to measure non-invasively changes in (13)C labelling of alanine and lactate with disease progression, following injection of hyperpolarised [1-(13)C]pyruvate.

RESULTS

Progressive decreases in the alanine/lactate concentration ratio and ALT/LDH activity ratio with disease progression were accompanied by a corresponding decrease in the [1-(13)C]alanine/[1-(13)C]lactate signal ratio observed in (13)C-MRSI images of the pancreas.

CONCLUSIONS

Metabolic imaging with hyperpolarised [1-(13)C]pyruvate enables detection and monitoring of the progression of PCa precursor lesions. Translation of this MRI technique to the clinic has the potential to improve the management of patients at high risk of developing PCa.

Heterogeneity of luminal breast cancer characterised by immunohistochemical expression of basal markers

BACKGROUND

Luminal A breast cancer defined as hormone receptor positive and human epidermal growth factor receptor 2 (HER2) negative is known to be heterogeneous. Previous study showed that luminal A tumours with the expression of basal markers ((cytokeratin (CK) 5 or CK5/6) or epidermal growth factor receptor (EGFR)) were associated with poorer prognosis compared with those that stained negative for basal markers. Prompted by this study, we assessed whether tumour characteristics and risk factors differed by basal marker status within luminal A tumours.

METHODS

We pooled 5040 luminal A cases defined by immunohistochemistry (4490 basal-negative ((CK5 (or CK5/6))- and EGFR-) and 550 basal-positive ((CK5 (or CK5/6+)) or EGFR+)) from eight studies participating in the Breast Cancer Association Consortium. Case-case comparison was performed using unconditional logistic regression.

RESULTS

Tumour characteristics and risk factors did not vary significantly by the expression of basal markers, although results suggested that basal-positive luminal tumours tended to be smaller and node negative, and were more common in women with a positive family history and lower body mass index.

CONCLUSIONS

Most established breast cancer risk factors were similar in basal-positive and basal-negative luminal A tumours. The non-significant but suggestive differences in tumour features and family history warrant further investigations.

Carbonic Anhydrase Activity Monitored In Vivo by Hyperpolarized 13C-Magnetic Resonance Spectroscopy Demonstrates Its Importance for pH Regulation in Tumors

Carbonic anhydrase buffers tissue pH by catalyzing the rapid interconversion of carbon dioxide (CO2) and bicarbonate (HCO3 (-)). We assessed the functional activity of CAIX in two colorectal tumor models, expressing different levels of the enzyme, by measuring the rate of exchange of hyperpolarized (13)C label between bicarbonate (H(13)CO3(-)) and carbon dioxide ((13)CO2), following injection of hyperpolarized H(13)CO3(-), using (13)C-magnetic resonance spectroscopy ((13)C-MRS) magnetization transfer measurements. (31)P-MRS measurements of the chemical shift of the pH probe, 3-aminopropylphosphonate, and (13)C-MRS measurements of the H(13)CO3(-)/(13)CO2 peak intensity ratio showed that CAIX overexpression lowered extracellular pH in these tumors. However, the (13)C measurements overestimated pH due to incomplete equilibration of the hyperpolarized (13)C label between the H(13)CO3(-) and (13)CO2 pools. Paradoxically, tumors overexpressing CAIX showed lower enzyme activity using magnetization transfer measurements, which can be explained by the more acidic extracellular pH in these tumors and the decreased activity of the enzyme at low pH. This explanation was confirmed by administration of bicarbonate in the drinking water, which elevated tumor extracellular pH and restored enzyme activity to control levels. These results suggest that CAIX expression is increased in hypoxia to compensate for the decrease in its activity produced by a low extracellular pH and supports the hypothesis that a major function of CAIX is to lower the extracellular pH.

Use of Ex Vivo Normothermic Perfusion for Quality Assessment of Discarded Human Donor Pancreases

A significant number of pancreases procured for transplantation are deemed unsuitable due to concerns about graft quality and the associated risk of complications. However, this decision is subjective and some declined grafts may be suitable for transplantation. Ex vivo normothermic perfusion (EVNP) prior to transplantation may allow a more objective assessment of graft quality and reduce discard rates. We report ex vivo normothermic perfusion of human pancreases procured but declined for transplantation, with ABO-compatible warm oxygenated packed red blood cells for 1-2 h. Five declined human pancreases were assessed using this technique after a median cold ischemia time of 13 h 19 min. One pancreas, with cold ischemia over 30 h, did not appear viable and was excluded. In the remaining pancreases, blood flow and pH were maintained throughout perfusion. Insulin secretion was observed in all four pancreases, but was lowest in an older donation after cardiac death pancreas. Amylase levels were highest in a gland with significant fat infiltration. This is the first study to assess the perfusion, injury, as measured by amylase, and exocrine function of human pancreases using EVNP and demonstrates the feasibility of the approach, although further refinements are required.

Crowdsourcing the General Public for Large Scale Molecular Pathology Studies in Cancer

BACKGROUND

Citizen science, scientific research conducted by non-specialists, has the potential to facilitate biomedical research using available large-scale data, however validating the results is challenging. The Cell Slider is a citizen science project that intends to share images from tumors with the general public, enabling them to score tumor markers independently through an internet-based interface.

METHODS

From October 2012 to June 2014, 98,293 Citizen Scientists accessed the Cell Slider web page and scored 180,172 sub-images derived from images of 12,326 tissue microarray cores labeled for estrogen receptor (ER). We evaluated the accuracy of Citizen Scientist's ER classification, and the association between ER status and prognosis by comparing their test performance against trained pathologists.

FINDINGS

The area under ROC curve was 0.95 (95% CI 0.94 to 0.96) for cancer cell identification and 0.97 (95% CI 0.96 to 0.97) for ER status. ER positive tumors scored by Citizen Scientists were associated with survival in a similar way to that scored by trained pathologists. Survival probability at 15 years were 0.78 (95% CI 0.76 to 0.80) for ER-positive and 0.72 (95% CI 0.68 to 0.77) for ER-negative tumors based on Citizen Scientists classification. Based on pathologist classification, survival probability was 0.79 (95% CI 0.77 to 0.81) for ER-positive and 0.71 (95% CI 0.67 to 0.74) for ER-negative tumors. The hazard ratio for death was 0.26 (95% CI 0.18 to 0.37) at diagnosis and became greater than one after 6.5 years of follow-up for ER scored by Citizen Scientists, and 0.24 (95% CI 0.18 to 0.33) at diagnosis increasing thereafter to one after 6.7 (95% CI 4.1 to 10.9) years of follow-up for ER scored by pathologists.

INTERPRETATION

Crowdsourcing of the general public to classify cancer pathology data for research is viable, engages the public and provides accurate ER data. Crowdsourced classification of research data may offer a valid solution to problems of throughput requiring human input.

Performance of automated scoring of ER, PR, HER2, CK5/6 and EGFR in breast cancer tissue microarrays in the Breast Cancer Association Consortium

Breast cancer risk factors and clinical outcomes vary by tumour marker expression. However, individual studies often lack the power required to assess these relationships, and large-scale analyses are limited by the need for high throughput, standardized scoring methods. To address these limitations, we assessed whether automated image analysis of immunohistochemically stained tissue microarrays can permit rapid, standardized scoring of tumour markers from multiple studies. Tissue microarray sections prepared in nine studies containing 20 263 cores from 8267 breast cancers stained for two nuclear (oestrogen receptor, progesterone receptor), two membranous (human epidermal growth factor receptor 2 and epidermal growth factor receptor) and one cytoplasmic (cytokeratin 5/6) marker were scanned as digital images. Automated algorithms were used to score markers in tumour cells using the Ariol system. We compared automated scores against visual reads, and their associations with breast cancer survival. Approximately 65-70% of tissue microarray cores were satisfactory for scoring. Among satisfactory cores, agreement between dichotomous automated and visual scores was highest for oestrogen receptor (Kappa = 0.76), followed by human epidermal growth factor receptor 2 (Kappa = 0.69) and progesterone receptor (Kappa = 0.67). Automated quantitative scores for these markers were associated with hazard ratios for breast cancer mortality in a dose-response manner. Considering visual scores of epidermal growth factor receptor or cytokeratin 5/6 as the reference, automated scoring achieved excellent negative predictive value (96-98%), but yielded many false positives (positive predictive value = 30-32%). For all markers, we observed substantial heterogeneity in automated scoring performance across tissue microarrays. Automated analysis is a potentially useful tool for large-scale, quantitative scoring of immunohistochemically stained tissue microarrays available in consortia. However, continued optimization, rigorous marker-specific quality control measures and standardization of tissue microarray designs, staining and scoring protocols is needed to enhance results.

Elevated levels of G-quadruplex formation in human stomach and liver cancer tissues

Four-stranded G-quadruplex DNA secondary structures have recently been visualized in the nuclei of human cultured cells. Here, we show that BG4, a G-quadruplex-specific antibody, can be used to stain DNA G-quadruplex structures in patient-derived tissues using immunohistochemistry. We observe a significantly elevated number of G-quadruplex-positive nuclei in human cancers of the liver and stomach as compared to background non-neoplastic tissue. Our results suggest that G-quadruplex formation can be detected and measured in patient-derived material and that elevated G-quadruplex formation may be a characteristic of some cancers.

SPARC independent drug delivery and antitumour effects of nab-paclitaxel in genetically engineered mice

DESIGN

Pharmacokinetic and pharmacodynamic parameters of cremophor-paclitaxel, nab-paclitaxel (human-albumin-bound paclitaxel, Abraxane) and a novel mouse-albumin-bound paclitaxel (m-nab-paclitaxel) were evaluated in genetically engineered mouse models (GEMMs) by liquid chromatography-tandem mass spectrometry (LC-MS/MS), histological and biochemical analysis. Preclinical evaluation of m-nab-paclitaxel included assessment by three-dimensional high-resolution ultrasound and molecular analysis in a novel secreted protein acidic and rich in cysteine (SPARC)-deficient GEMM of pancreatic ductal adenocarcinoma (PDA).

RESULTS

nab-Paclitaxel exerted its antitumoural effects in a dose-dependent manner and was associated with less toxicity compared with cremophor-paclitaxel. SPARC nullizygosity in a GEMM of PDA, Kras(G12D);p53(flox/-);p48Cre (KPfC), resulted in desmoplastic ductal pancreas tumours with impaired collagen maturation. Paclitaxel concentrations were significantly decreased in SPARC null plasma samples and tissues when administered as low-dose m-nab-paclitaxel. At the maximally tolerated dose, SPARC deficiency did not affect the intratumoural paclitaxel concentration, stromal deposition and the immediate therapeutic response.

CONCLUSIONS

nab-Paclitaxel accumulates and acts in a dose-dependent manner. The interaction of plasma SPARC and albumin-bound drugs is observed at low doses of nab-paclitaxel but is saturated at therapeutic doses in murine tumours. Thus, this study provides important information for future preclinical and clinical trials in PDA using nab-paclitaxel in combination with novel experimental and targeted agents.

HES6 drives a critical AR transcriptional programme to induce castration-resistant prostate cancer through activation of an E2F1-mediated cell cycle network

Castrate-resistant prostate cancer (CRPC) is poorly characterized and heterogeneous and while the androgen receptor (AR) is of singular importance, other factors such as c-Myc and the E2F family also play a role in later stage disease. HES6 is a transcription co-factor associated with stem cell characteristics in neural tissue. Here we show that HES6 is up-regulated in aggressive human prostate cancer and drives castration-resistant tumour growth in the absence of ligand binding by enhancing the transcriptional activity of the AR, which is preferentially directed to a regulatory network enriched for transcription factors such as E2F1. In the clinical setting, we have uncovered a HES6-associated signature that predicts poor outcome in prostate cancer, which can be pharmacologically targeted by inhibition of PLK1 with restoration of sensitivity to castration. We have therefore shown for the first time the critical role of HES6 in the development of CRPC and identified its potential in patient-specific therapeutic strategies.

Antibody validation of immunohistochemistry for biomarker discovery: recommendations of a consortium of academic and pharmaceutical based histopathology researchers

As biomarker discovery takes centre-stage, the role of immunohistochemistry within that process is increasing. At the same time, the number of antibodies being produced for “research use” continues to rise and it is important that antibodies to be used as biomarkers are validated for specificity and sensitivity before use. This guideline seeks to provide a stepwise approach for the validation of an antibody for immunohistochemical assays, reflecting the views of a consortium of academic and pharmaceutical based histopathology researchers. We propose that antibodies are placed into a tier system, level 1–3, based on evidence of their usage in immunohistochemistry, and that the degree of validation required is proportionate to their place on that tier.

A metadata-aware application for remote scoring and exchange of tissue microarray images

BACKGROUND

The use of tissue microarrays (TMA) and advances in digital scanning microscopy has enabled the collection of thousands of tissue images. There is a need for software tools to annotate, query and share this data amongst researchers in different physical locations.

RESULTS

We have developed an open source web-based application for remote scoring of TMA images, which exploits the value of Microsoft Silverlight Deep Zoom to provide a intuitive interface for zooming and panning around digital images. We use and extend existing XML-based standards to ensure that the data collected can be archived and that our system is interoperable with other standards-compliant systems.

CONCLUSION

The application has been used for multi-centre scoring of TMA slides composed of tissues from several Phase III breast cancer trials and ten different studies participating in the International Breast Cancer Association Consortium (BCAC). The system has enabled researchers to simultaneously score large collections of TMA and export the standardised data to integrate with pathological and clinical outcome data, thereby facilitating biomarker discovery.

Gamma secretase inhibition promotes hypoxic necrosis in mouse pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) is a highly lethal disease that is refractory to medical intervention. Notch pathway antagonism has been shown to prevent pancreatic preneoplasia progression in mouse models, but potential benefits in the setting of an established PDA tumor have not been established. We demonstrate that the gamma secretase inhibitor MRK003 effectively inhibits intratumoral Notch signaling in the KPC mouse model of advanced PDA. Although MRK003 monotherapy fails to extend the lifespan of KPC mice, the combination of MRK003 with the chemotherapeutic gemcitabine prolongs survival. Combination treatment kills tumor endothelial cells and synergistically promotes widespread hypoxic necrosis. These results indicate that the paucivascular nature of PDA can be exploited as a therapeutic vulnerability, and the dual targeting of the tumor endothelium and neoplastic cells by gamma secretase inhibition constitutes a rationale for clinical translation.

Bcl-2 and β1-integrin predict survival in a tissue microarray of small cell lung cancer

INTRODUCTION

Survival in small cell lung cancer (SCLC) is limited by the development of chemoresistance. Factors associated with chemoresistance in vitro have been difficult to validate in vivo. Both Bcl-2 and β(1)-integrin have been identified as in vitro chemoresistance factors in SCLC but their importance in patients remains uncertain. Tissue microarrays (TMAs) are useful to validate biomarkers but no large TMA exists for SCLC. We designed an SCLC TMA to study potential biomarkers of prognosis and then used it to clarify the role of both Bcl-2 and β(1)-integrin in SCLC.

METHODS

A TMA was constructed consisting of 184 cases of SCLC and stained for expression of Bcl-2 and β(1)-integrin. The slides were scored and the role of the proteins in survival was determined using Cox regression analysis. A meta-analysis of the role of Bcl-2 expression in SCLC prognosis was performed based on published results.

RESULTS

Both proteins were expressed at high levels in the SCLC cases. For Bcl-2 (n=140), the hazard ratio for death if the staining was weak in intensity was 0.55 (0.33-0.94, P=0.03) and for β(1)-integrin (n=151) was 0.60 (0.39-0.92, P=0.02). The meta-analysis showed an overall hazard ratio for low expression of Bcl-2 of 0.91(0.74-1.09).

CONCLUSIONS

Both Bcl-2 and β(1)-integrin are independent prognostic factors in SCLC in this cohort although further validation is required to confirm their importance. A TMA of SCLC cases is feasible but challenging and an important tool for biomarker validation.

Abstract PR2: Therapeutic intervention targeting a Hedgehog-dependent barrier to drug delivery in pancreatic cancer

Ductal pancreatic tumors are unusually resistant to chemotherapy, exhibiting primary resistance to each of the numerous regimens tested to date. These tumors are also unusually desmoplastic and harbor a sparse and inefficient vasculature. The resulting lack of perfusion appears to play a role in the inefficient delivery of numerous chemotherapeutic agents to the parenchyma of pancreatic tumors. Recent evidence has implicated the sonic hedgehog pathway in promoting desmoplasia through a paracrine signaling mechanism active in pancreatic tumors of both humans and the Kras/p53/PdxCre (KPC) mouse model. We sought to evaluate the dependence of stromal desmoplasia on Hedgehog (Hh) pathway signaling and, by extension, assess the effects of Hh pathway inhibition on drug delivery and chemoresistance.

Using IPI-926, a semisynthetic inhibitor of the Smoothened protein, we found that stromal contribution was markedly diminished within 10 days of inhibition of the Hh pathway. Paradoxically, the depletion of stromal cells was coincident with an increase in microvessel density, despite previous data indicating a pro-angiogenic role for the Hh pathway. These non-cell autonomous changes resulted in an increase in the delivery of small molecules to KPC pancreatic tumors and an increase in apoptosis when administered in combination with gemcitabine. Ultimately, mice treated with both IPI-926 and gemcitabine had a significant extension of survival and a decrease in the incidence of liver metastases. We conclude that the Hh pathway plays an important role in the maintenance of pancreatic tumor stroma and that this contributes to the primary chemoresistance of pancreatic tumors. These data also support the clinical evaluation of agents that target the stroma in pancreatic cancer.

Citation Information: Clin Cancer Res 2010;16(14 Suppl):PR2.

Assessment of automated image analysis of breast cancer tissue microarrays for epidemiologic studies

BACKGROUND

A major challenge in studies of etiologic heterogeneity in breast cancer has been the limited throughput, accuracy, and reproducibility of measuring tissue markers. Computerized image analysis systems may help address these concerns, but published reports of their use are limited. We assessed agreement between automated and pathologist scores of a diverse set of immunohistochemical assays done on breast cancer tissue microarrays (TMA).

METHODS

TMAs of 440 breast cancers previously stained for estrogen receptor (ER)-alpha, progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), ER-beta, and aromatase were independently scored by two pathologists and three automated systems (TMALab II, TMAx, and Ariol). Agreement between automated and pathologist scores of negative/positive was measured using the area under the receiver operating characteristics curve (AUC) and weighted kappa statistics for categorical scores. We also investigated the correlation between immunohistochemical scores and mRNA expression levels.

RESULTS

Agreement between pathologist and automated negative/positive and categorical scores was excellent for ER-alpha and PR (AUC range = 0.98-0.99; kappa range = 0.86-0.91). Lower levels of agreement were seen for ER-beta categorical scores (AUC = 0.99-1.0; kappa = 0.80-0.86) and both negative/positive and categorical scores for aromatase (AUC = 0.85-0.96; kappa = 0.41-0.67) and HER2 (AUC = 0.94-0.97; kappa = 0.53-0.72). For ER-alpha and PR, there was a strong correlation between mRNA levels and automated (rho = 0.67-0.74) and pathologist immunohistochemical scores (rho = 0.67-0.77). HER2 mRNA levels were more strongly correlated with pathologist (rho = 0.63) than automated immunohistochemical scores (rho = 0.41-0.49).

CONCLUSIONS

Automated analysis of immunohistochemical markers is a promising approach for scoring large numbers of breast cancer tissues in epidemiologic investigations. This would facilitate studies of etiologic heterogeneity, which ultimately may allow improved risk prediction and better prevention approaches.

Resin technologies: construction and staining of resin TMA's

The traditional formaldehyde-fixed paraffin-embedded tissue, and therefore the tissue microarrays created from it, provide good morphology but with a compromised antigenicity when compared to frozen tissue. In contrast, while solving the issue of antigenicity, frozen tissue suffers from a lack of morphology. We have demonstrated that tissue microarrays constructed in glycol methacrylate resin, when combined with a cold acetone fixation step, have been able to combine the superior morphology of resin-embedded sections with the superior antigenicity of frozen tissue for prospectively collected material.

Irradiated Blm-deficient mice are a highly tumor prone model for analysis of a broad spectrum of hematologic malignancies

Mutations in the BLM gene cause human Bloom syndrome (BS), an autosomal recessive disorder of growth retardation, immunodeficiency and cancer predisposition. Homozygous null Blm(m3/m3) mice are cancer prone with a 5-fold increased risk of cancer compared with Blm(m3/+) and Blm(+/+) mice. Irradiation of Blm(m3/m3) mice increased the risk to 28-fold. Tumors occurred mainly in the hematopoietic system and were similar to those in BS based on detailed histologic and immunohistochemical analyses. Irradiated Blm-deficient mice thus provide a novel model for understanding accelerated malignancies in BS and a new platform for investigating the molecular basis for a wide range of hematopoietic neoplasms.

Inhibition of Hedgehog signaling enhances delivery of chemotherapy in a mouse model of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is among the most lethal human cancers in part because it is insensitive to many chemotherapeutic drugs. Studying a mouse model of PDA that is refractory to the clinically used drug gemcitabine, we found that the tumors in this model were poorly perfused and poorly vascularized, properties that are shared with human PDA. We tested whether the delivery and efficacy of gemcitabine in the mice could be improved by coadministration of IPI-926, a drug that depletes tumor-associated stromal tissue by inhibition of the Hedgehog cellular signaling pathway. The combination therapy produced a transient increase in intratumoral vascular density and intratumoral concentration of gemcitabine, leading to transient stabilization of disease. Thus, inefficient drug delivery may be an important contributor to chemoresistance in pancreatic cancer.

Inhibition of Hedgehog signaling enhances delivery of chemotherapy in a mouse model of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is among the most lethal human cancers in part because it is insensitive to many chemotherapeutic drugs. Studying a mouse model of PDA that is refractory to the clinically used drug gemcitabine, we found that the tumors in this model were poorly perfused and poorly vascularized, properties that are shared with human PDA. We tested whether the delivery and efficacy of gemcitabine in the mice could be improved by coadministration of IPI-926, a drug that depletes tumor-associated stromal tissue by inhibition of the Hedgehog cellular signaling pathway. The combination therapy produced a transient increase in intratumoral vascular density and intratumoral concentration of gemcitabine, leading to transient stabilization of disease. Thus, inefficient drug delivery may be an important contributor to chemoresistance in pancreatic cancer.

Inhibition of Hedgehog signaling enhances delivery of chemotherapy in a mouse model of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is among the most lethal human cancers in part because it is insensitive to many chemotherapeutic drugs. Studying a mouse model of PDA that is refractory to the clinically used drug gemcitabine, we found that the tumors in this model were poorly perfused and poorly vascularized, properties that are shared with human PDA. We tested whether the delivery and efficacy of gemcitabine in the mice could be improved by coadministration of IPI-926, a drug that depletes tumor-associated stromal tissue by inhibition of the Hedgehog cellular signaling pathway. The combination therapy produced a transient increase in intratumoral vascular density and intratumoral concentration of gemcitabine, leading to transient stabilization of disease. Thus, inefficient drug delivery may be an important contributor to chemoresistance in pancreatic cancer.

High Numbers of Tumor-Infiltrating Programmed Cell Death 1–Positive Regulatory Lymphocytes Are Associated With Improved Overall Survival in Follicular Lymphoma

Purpose

Tumor microenvironment influences the behavior of follicular lymphoma (FL), although the specific cell subsets involved are not well known. The aim of this study was to determine the impact of programmed cell death 1 (PD-1) –positive inhibitory immunoregulatory lymphoid cells in the clinicobiologic features and outcome of patients with FL.

Patients and Methods

We examined samples from 100 patients (53 men and 47 women; median age, 54 years) at diagnosis, as well as in 32 patients at first relapse, with a recently generated monoclonal antibody against PD-1. The cells were quantified using computerized image analysis. Additional analysis consisted of double immunofluorescence and flow cytometry.

Results

PD-1 expression was alternative to FOXP3 in lymphoid cells from both reactive tonsils and FL. At diagnosis, the median percentage of PD-1–positive cells was 14% (range, 0.1% to 74%). Patients with grade 3 FL, poor performance status, and high serum lactate dehydrogenase showed lower numbers of PD-1–positive cells. After a median follow-up of 6.2 years, patients with PD-1–positive cells ≤ 5% (n = 25), 6% to 33% (n = 50), and more than 33% (n = 25) had a 5-year progression-free survival rate of 20%, 46%, and 48% (P = .038) and overall survival (OS) of 50%, 77%, and 95% (P = .004), respectively. PD-1 and FL International Prognostic Index maintained prognostic value for OS in multivariate analysis. Patients with PD-1–positive cells ≤ 5% showed a higher risk of histologic transformation. At that time, transformed diffuse large B-cell lymphomas had lower percentage of PD-1–positive cells than FL.

Conclusion

A high content of PD-1–positive cells predicted favorable outcome of FL patients, whereas a marked reduction is observed in transformation.

Regulation of ERBB2 by oestrogen receptor-PAX2 determines response to tamoxifen

Crosstalk between the oestrogen receptor (ER) and ERBB2/HER-2 pathways has long been implicated in breast cancer aetiology and drug response, yet no direct connection at a transcriptional level has been shown. Here we show that oestrogen-ER and tamoxifen-ER complexes directly repress ERBB2 transcription by means of a cis-regulatory element within the ERBB2 gene in human cell lines. We implicate the paired box 2 gene product (PAX2), in a previously unrecognized role, as a crucial mediator of ER repression of ERBB2 by the anti-cancer drug tamoxifen. We show that PAX2 and the ER co-activator AIB-1/SRC-3 compete for binding and regulation of ERBB2 transcription, the outcome of which determines tamoxifen response in breast cancer cells. The repression of ERBB2 by ER-PAX2 links these two breast cancer subtypes and suggests that aggressive ERBB2-positive tumours can originate from ER-positive luminal tumours by circumventing this repressive mechanism. These data provide mechanistic insight into the molecular basis of endocrine resistance in breast cancer.

Application of phage display to high throughput antibody generation and characterization

A phage display library has been constructed containing over 1010 human antibodies, allowing the large-scale generation of antibodies. Over 38,000 recombinant antibodies against 292 antigens were selected, screened and sequenced, and 4,400 resultant unique clones characterized further.

We have created a high quality phage display library containing over 10¹⁰ human antibodies and describe its use in the generation of antibodies on an unprecedented scale. We have selected, screened and sequenced over 38,000 recombinant antibodies to 292 antigens, yielding over 7,200 unique clones. 4,400 antibodies were characterized by specificity testing and detailed sequence analysis and the data/clones are available online. Sensitive detection was demonstrated in a bead based flow cytometry assay. Furthermore, positive staining by immunohistochemistry on tissue microarrays was found for 37% (143/381) of antibodies. Thus, we have demonstrated the potential of and illuminated the issues associated with genome-wide monoclonal antibody generation.

Resin Tissue Microarrays: a Universal Format for Immunohistochemistry

Tissue microarray (TMA) technology allows the miniaturization and characterization of multiple tissue samples on a single slide and commonly uses formalin-fixed paraffin-embedded (FFPE) tissue or acetone-fixed frozen tissue. The former provides good morphology but can compromise antigenicity, whereas the latter provides compromised morphology with good antigenicity. Here, we report the development of TMAs in glycol methacrylate resin, which combine the advantages of both methods in one embedding format. Freshly collected tissue fixed in -20C acetone or 10% neutral buffered formaldehyde were cored and arrayed into an intermediary medium of 2% agarose before infiltration of the agarose array with glycol methacrylate resin. Acetone-fixed resin TMA demonstrated improved morphology over acetone-fixed frozen TMA, with no loss of antigenicity. Staining for extracellular, cell surface, and nuclear antigens could be realized with monoclonal and polyclonal antibodies as well as with monomeric single-chain Fv preparations. In addition, when compared with FFPE TMA, formalin-fixed tissue in a resin TMA gave enhanced morphology and subcellular detail. Therefore, resin provides a universal format for the construction of TMAs, providing improved tissue morphology while retaining antigenicity, allows thin-section preparation, and could be used to replace preparation of frozen and FFPE TMAs for freshly collected tissue.

Distribution of basement membrane pores in bronchus revealed by microscopy following epithelial removal

The basement membrane of the bronchial epithelium separates the epithelial and mesenchymal compartments. Basement membrane pores allow cells to cross this boundary. We present a method for preparation of samples of human basement membrane allowing us easy visualisation and characterisation of the distribution and persistence of these pores. Columnar epithelial cells were removed from airway samples with gentle scraping with a circular glass coverslip. In contrast, the underlying basal cells required incubation once in dithiothreitol and twice in ethylenediaminetetraacetic acid. Scanning electron microscopy (SEM) at each stage of the epithelial stripping process showed the selective removal of epithelial cells with eventual visualisation of the pores. Using confocal microscopy on blocks of viable tissue, pores were shown to persist in culture for at least 5 days, despite the presence of viable cells in the submucosa. The distribution of pores in tissues determined by SEM was compared to simulations of three distribution patterns (random, clumped, and distributed). The pattern of pores in the samples was consistent with a random distribution. We suggest that basement membrane pores can be generated by the passage of infiltrating cells into the epithelium providing a network suitable for intraepithelial surveillance.

TGF-beta isoform release and activation during in vitro bronchial epithelial wound repair

Restitution of an epithelial layer after environmental or biological damage is important to maintain the normal function of the respiratory tract. We have investigated the role of transforming growth factor (TGF)-beta isoforms in the repair of layers of 16HBE 14o(-) bronchial epithelial-derived cells after damage by multiple scoring. ELISA showed that both latent TGF-beta1 and TGF-beta2 were converted to their active forms 2 h after wounding. Time-lapse microscopy showed that the addition of TGF-beta1, but not TGF-beta2, progressively increased the rate of migration of damaged monolayers at concentrations down to 250 pg/ml. This increase was blocked by addition of a neutralizing TGF-beta1 antibody. Phase-contrast microscopy and inhibition of proliferation with mitomycin C showed that proliferation was not required for migration. These results demonstrate that conversion of latent to active TGF-beta1 and TGF-beta2 during in vitro epithelial wound repair occurs quickly and that TGF-beta1 speeds epithelial repair. A faster repair may be advantageous in preventing access of environmental agents to the internal milieu of the lung although the production of active TGF-beta molecules may augment subepithelial fibrosis.

Basement membrane pores in human bronchial epithelium: a conduit for infiltrating cells?

This study reports the presence of oval-shaped pores in the basement membrane of the human bronchial airway that may be used as conduits for immune cells to traffic between the epithelial and mesenchymal compartments. Human bronchial mucosa collected after surgery was stripped of epithelial cells without damaging the basement membrane. Both scanning and transmission electron microscopy showed oval-shaped pores 0.75 to 3.85 microm in diameter in the bronchial basement membrane at a density of 863 pores/mm2. Transmission electron microscopy showed that the pores spanned the full depth of the basement membrane, with a concentration of collagen-like fibers at the lateral edges of the pore. Infiltrating cells apparently moved through the pores, both in the presence and absence of the epithelium. Taken together, these results suggest that immune cells use basement membrane pores as predefined routes to move between the epithelial and mesenchymal compartments without disruption of the basement membrane. As a persistent feature of the basement membrane, pores could facilitate inflammatory cell access to the epithelium and greatly increase the frequency of intercellular contact between trafficking cells.

Pulmonary immunopathology of sudden infant death syndrome

Sudden infant death syndrome (SIDS) is the most common cause of postneonatal mortality in the UK. Pathological investigations have shown evidence suggestive of respiratory obstruction with subsequent hypoxia leading to death. We examined 48 infants who died of SIDS and 30 who died of other, non-pulmonary, causes and identified pulmonary eosinophil and neutrophil leucocytes, mast cells, and T and B lymphocytes by immunocytochemistry. Positively stained cells were counted in the parenchyma and around the bronchi without knowledge of the tissue source. The results showed three times more eosinophils in the lungs of infants who died of SIDS (27.61 vs 7.91 [99% CI 1.76-5.87] cells/mm2 for parenchyma) accompanied by increased T lymphocytes and B lymphocytes. There were more peribronchial mast cells in the SIDS group (22.1 vs 14.7 [1.03-2.10] cells/mm2) and insignificant differences in neutrophils and parenchymal mast cells. There were significant associations between eosinophil, B lymphocyte, and T lymphocyte numbers. These findings provide evidence for an abnormal T lymphocyte-mediated pulmonary inflammatory response in SIDS. Products of eosinophil degranulation can cause epithelial damage and pulmonary oedema, which could cause the respiratory obstruction and hypoxia associated with SIDS.