Adult stem cell activity in naked mole rats for long-term tissue maintenance

The naked mole rat (NMR), Heterocephalus glaber, the longest-living rodent, provides a unique opportunity to explore how evolution has shaped adult stem cell (ASC) activity and tissue function with increasing lifespan. Using cumulative BrdU labelling and a quantitative imaging approach to track intestinal ASCs (Lgr5+) in their native in vivo state, we find an expanded pool of Lgr5+ cells in NMRs, and these cells specifically at the crypt base (Lgr5+CBC) exhibit slower division rates compared to those in short-lived mice but have a similar turnover as human LGR5+CBC cells. Instead of entering quiescence (G0), NMR Lgr5+CBC cells reduce their division rates by prolonging arrest in the G1 and/or G2 phases of the cell cycle. Moreover, we also observe a higher proportion of differentiated cells in NMRs that confer enhanced protection and function to the intestinal mucosa which is able to detect any chemical imbalance in the luminal environment efficiently, triggering a robust pro-apoptotic, anti-proliferative response within the stem/progenitor cell zone.

Novel Pathogenic Mutation Mapping of ASPM Gene in Consanguineous Pakistani Families with Primary Microcephaly

Autosomal recessive primary microcephaly (MCPH) is a neurodevelopmental disorder characterized by a congenitally reduced head circumference (-3 to -5 SD) and non-progressive intellectual disability. The objective of the study was to evaluate pathogenic mutations in the ASPM gene to understand etiology and molecular mechanism of primary microcephaly. Blood samples were collected from various families across different remote areas of Pakistan from February 2017 to May 2019 who were identified to be affected with primary microcephaly. DNA extraction was performed using the salting-out method; the quality and quantity of DNA were evaluated using spectrophotometry and 1% agarose gel electrophoresis, respectively in University of the Punjab. Mutation analysis was performed by whole exome sequencing from the Cologne Center for Genomics, University of Cologne. Sanger sequencing was done in University of the Punjab to confirm the pathogenic nature of mutation. A novel 4-bp deletion mutation c.3877_3880delGAGA was detected in exon 17 of the ASPM gene in two primary microcephaly affected families (A and B), which resulted in a frame shift mutation in the gene followed by truncated protein synthesis (p.Glu1293Lysfs*10), as well as the loss of the calmodulin-binding IQ domain and the Armadillo-like domain in the ASPM protein. Using the in-silico tools Mutation Taster, PROVEAN, and PolyPhen, the pathogenic effect of this novel mutation was tested; it was predicted to be "disease causing," with high pathogenicity scores. One previously reported mutation in exon 24 (c.9730C>T) of the ASPM gene resulting in protein truncation (p.Arg3244*) was also observed in family C. Mutations in the ASPM gene are the most common cause of MCPH in most cases. Therefore, enrolling additional affected families from remote areas of Pakistan would help in identifying or mapping novel mutations in the ASPM gene of primary microcephaly.

The NeST (Neoadjuvant systemic therapy in breast cancer) study: National Practice Questionnaire of United Kingdom multi-disciplinary decision making

BACKGROUND

Neoadjuvant systemic therapy (NST) is increasingly used in the treatment of breast cancer, yet it is clear that there is significant geographical variation in its use in the UK. This study aimed to examine stated practice across UK breast units, in terms of indications for use, radiological monitoring, pathological reporting of treatment response, and post-treatment surgical management.

METHODS

Multidisciplinary teams (MDTs) from all UK breast units were invited to participate in the NeST study. A detailed questionnaire assessing current stated practice was distributed to all participating units in December 2017 and data collated securely usingREDCap. Descriptive statistics were calculated for each questionnaire item.

RESULTS

Thirty-nine MDTs from a diverse range of hospitals responded. All MDTs routinely offered neoadjuvant chemotherapy (NACT) to a median of 10% (range 5-60%) of patients. Neoadjuvant endocrine therapy (NET) was offered to a median of 4% (range 0-25%) of patients by 66% of MDTs. The principal indication given for use of neoadjuvant therapy was for surgical downstaging. There was no consensus on methods of radiological monitoring of response, and a wide variety of pathological reporting systems were used to assess tumour response. Twenty-five percent of centres reported resecting the original tumour footprint, irrespective of clinical/radiological response. Radiologically negative axillae at diagnosis routinely had post-NACT or post-NET sentinel lymph node biopsy (SLNB) in 73.0 and 84% of centres respectively, whereas 16% performed SLNB pre-NACT. Positive axillae at diagnosis would receive axillary node clearance at 60% of centres, regardless of response to NACT.

DISCUSSION

There is wide variation in the stated use of neoadjuvant systemic therapy across the UK, with general low usage of NET. Surgical downstaging remains the most common indication of the use of NAC, although not all centres leverage the benefits of NAC for de-escalating surgery to the breast and/or axilla. There is a need for agreed multidisciplinary guidance for optimising selection and management of patients for NST. These findings will be corroborated in phase II of the NeST study which is a national collaborative prospective audit of NST utilisation and clinical outcomes.

The NeST (neoadjuvant systemic therapy in breast cancer) study - Protocol for a prospective multi-centre cohort study to assess the current utilization and short-term outcomes of neoadjuvant systemic therapies in breast cancer

INTRODUCTION

Neoadjuvant systemic therapy (NST) has several potential advantages in the treatment of breast cancer. However, there is currently considerable variation in NST use across the UK. The NeST study is a national, prospective, multicentre cohort study that will investigate current patterns of care with respect to NST in the UK.

METHODS AND ANALYSIS

Phase 1 - a national practice questionnaire (NPQ) to survey current practice.Phase 2 - a multi-centre prospective cohort study of breast cancer patients, undergoing NST.Women undergoing NST as their MDT recommended primary breast cancer treatment between December 2017 and May 2018 will be included. The breast surgery and oncological professional associations and the trainee research collaborative networks will encourage participation by all breast cancer centres.Patient demographics, radiological, oncological, surgical and pathological data will be collected, including complications and the need for further intervention/treatment. Data will be collated to establish current practice in the UK, regarding NST usage and variability of access and provision of these therapies. Prospective data on 600 patients from ~50 centres are anticipated.Trial registration: ISRCTN11160072.

ETHICS AND DISSEMINATION

Research ethics approval is not required for this study, as per the online Health Research Authority decision tool. The information obtained will provide valuable insights to help patients make informed decisions about their treatment. These data should establish current practice in the UK concerning NST, inform future service delivery as well as identifying further research questions.This protocol will be disseminated through the Mammary Fold Academic Research Collaborative (MFAC), the Reconstructive Surgery Trials Network and the Association of Breast Surgery. Participating units will have access to their own data and collective results will be presented at relevant conferences and published in appropriate peer-reviewed journals, as well as being made accessible to relevant patient groups.

Serum- and Glucocorticoid-induced Kinase Sgk1 Directly Promotes the Differentiation of Colorectal Cancer Cells and Restrains Metastasis

PURPOSE

The molecular events that determine intestinal cell differentiation are poorly understood and it is unclear whether it is primarily a passive event or an active process. It is clinically important to gain a greater understanding of the process, because in colorectal cancer, the degree of differentiation of a tumor is associated with patient survival. SGK1 has previously been identified as a gene that is principally expressed in differentiated intestinal cells. In colorectal cancer, there is marked downregulation of SGK1 compared with normal tissue.Experimental Design: An inducible SGK1 viral overexpression system was utilized to induce reexpression of SGK1 in colorectal cancer cell lines. Transcriptomic and phenotypic analyses of these colorectal cancer lines was performed and validation in mouse and human cohorts was performed.

RESULTS

We demonstrate that SGK1 is upregulated in response to, and an important controller of, intestinal cell differentiation. Reexpression of SGK1 in colorectal cancer cell lines results in features of differentiation, decreased migration rates, and inhibition of metastasis in an orthotopic xenograft model. These effects may be mediated, in part, by SGK1-induced PKP3 expression and increased degradation of MYC.

CONCLUSIONS

Our results suggest that SGK1 is an important mediator of differentiation of colorectal cells and may inhibit colorectal cancer metastasis.

AllergoOncology: Opposite outcomes of immune tolerance in allergy and cancer

While desired for the cure of allergy, regulatory immune cell subsets and nonclassical Th2-biased inflammatory mediators in the tumour microenvironment can contribute to immune suppression and escape of tumours from immunological detection and clearance. A key aim in the cancer field is therefore to design interventions that can break immunological tolerance and halt cancer progression, whereas on the contrary allergen immunotherapy exactly aims to induce tolerance. In this position paper, we review insights on immune tolerance derived from allergy and from cancer inflammation, focusing on what is known about the roles of key immune cells and mediators. We propose that research in the field of AllergoOncology that aims to delineate these immunological mechanisms with juxtaposed clinical consequences in allergy and cancer may point to novel avenues for therapeutic interventions that stand to benefit both disciplines.

Bone morphogenetic protein and Notch signalling crosstalk in poor-prognosis, mesenchymal-subtype colorectal cancer

The functional role of bone morphogenetic protein (BMP) signalling in colorectal cancer (CRC) is poorly defined, with contradictory results in cancer cell line models reflecting the inherent difficulties of assessing a signalling pathway that is context-dependent and subject to genetic constraints. By assessing the transcriptional response of a diploid human colonic epithelial cell line to BMP ligand stimulation, we generated a prognostic BMP signalling signature, which was applied to multiple CRC datasets to investigate BMP heterogeneity across CRC molecular subtypes. We linked BMP and Notch signalling pathway activity and function in human colonic epithelial cells, and normal and neoplastic tissue. BMP induced Notch through a γ-secretase-independent interaction, regulated by the SMAD proteins. In homeostasis, BMP/Notch co-localization was restricted to cells at the top of the intestinal crypt, with more widespread interaction in some human CRC samples. BMP signalling was downregulated in the majority of CRCs, but was conserved specifically in mesenchymal-subtype tumours, where it interacts with Notch to induce an epithelial-mesenchymal transition (EMT) phenotype. In intestinal homeostasis, BMP-Notch pathway crosstalk is restricted to differentiating cells through stringent pathway segregation. Conserved BMP activity and loss of signalling stringency in mesenchymal-subtype tumours promotes a synergistic BMP-Notch interaction, and this correlates with poor patient prognosis. BMP signalling heterogeneity across CRC subtypes and cell lines can account for previous experimental contradictions. Crosstalk between the BMP and Notch pathways will render mesenchymal-subtype CRC insensitive to γ-secretase inhibition unless BMP activation is concomitantly addressed. © 2017 The Authors. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Abstract P2-04-07: Immune profiling of post neoadjuvant high metastatic risk (RCB-II/III) residual disease in patients with early triple negative breast cancers

Background: Poor prognosis in TNBC can be predicted in the significant fraction of patients with large volume residual cancer burden (RCB-II/III) after neoadjuvant chemotherapy (NACT). Whilst residual disease has been characterised to identify “driver” mutations and copy number variations, the contribution of the immune response within its tumour microenvironment remains unclear. Here we aimed to: 1) assess the potential spatial heterogeneity of immune transcript related gene expression between areas of tumour approximately 1cm apart as might still occur with a radiologically guided biopsy through the residual disease; and 2) assess the immune stroma composition of the TNBC high metastatic risk RCB II/III disease.

Method: 12 TNBC post NACT RCB II/III residual cases were identified from the KHP biobank. H&E sections were reviewed and areas of tumor 1cm apart within a residual resection specimen marked as area A and area B. HistoQuest analysis software was used to quantify the proportion of tumor infiltrating lymphocytes (per total cell count) within both areas. RNA was extracted from both areas and immune gene expression profiling performed using a Nanostring nCounter® on all 24 samples. The immune PanCancer panel consisted of 770 genes combining markers for different immune cell populations. Differential genes between paired samples were compared and unsupervised hierarchical clustering using 770 genes and immune cell types performed.

Results:Quantitative comparison of the tumour infiltrating lymphocytes (TILS) between area A and B revealed that 73% (8/11) of the cases had a <2-fold difference in the percentage of TILS within a residual specimen; and 27% (3/11) displayed a >2-fold (range 2.03-3.16) difference in the TILS. When comparing the 770 gene expression profiles between sampling areas in the same tumour, we found little spatial heterogeneity with areas A/B clustering together in 10 out of 12 cases. Interestingly, the two cases that revealed spatial heterogeneity within the paired samples displayed little immune cell heterogeneity histologically (i.e. <1-fold change in the TILS percentage score between area A and B). Comparing patient samples by immune gene expression profiling divided the patients into two groups: i) those with immunologically enriched tumors in whom gene signatures for majority of the immune cell types (DC, Macrophages, CD8+T-cells, T-helper cells (Th17, Th2, Th1), Tregs, NK, B-cells, Neutrophils, Mast cells) were highly expressed and ii) those with immunologically inert tumors in whom the immune cell signatures were not highly expressed. Within our patient cohort, patients with immunologically enriched gene expression profiles were also seen to display higher TILS score (ranging between 28.17% to 40.66%) as compared to patients with immunologically inert gene expression with scores ranging from 11.82% to 16.80%.

Conclusion: The findings that high metastatic risk residual disease can be further characterized as either “immunologically inert” or “immunologically enriched” at the level of extensive immunological transcript gene expression and by histological assessment of TILS requires further investigation; and is being validated in a larger sample set.

Citation Format: Irshad S, Cheang M, Gazinka P, Naidoo K, Buus R, Pinder S, Dowsett M, Tutt A. Immune profiling of post neoadjuvant high metastatic risk (RCB-II/III) residual disease in patients with early triple negative breast cancers [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-04-07.

Microenvironmental control of stem cell fate in intestinal homeostasis and disease

The conventional model of intestinal epithelial architecture describes a unidirectional tissue organizational hierarchy with stem cells situated at the crypt base and daughter cells proliferating and terminally differentiating as they progress along the vertical (crypt-luminal) axis. In this model, the fate of a cell that has left the niche is determined and its lifespan limited. Evidence is accumulating to suggest that stem cell control and daughter cell fate determination is not solely an intrinsic, cell autonomous property but is heavily influenced by the microenvironment including paracrine, mesenchymal, and endogenous epithelial morphogen gradients. Recent research suggests that in intestinal homeostasis, stem cells transit reversibly between states of variable competence in the niche. Furthermore, selective pressures that disrupt the homeostatic balance, such as intestinal inflammation or morphogen dysregulation, can cause committed progenitor cells and even some differentiated cells to regain stem cell properties. Importantly, it has been recently shown that this disruption of cell fate determination can lead to somatic mutation and neoplastic transformation of cells situated outside the crypt base stem cell niche. This paper reviews the exciting developments in the study of stem cell dynamics in homeostasis, intestinal regeneration, and carcinogenesis, and explores the implications for human disease and cancer therapies.

Aberrant epithelial GREM1 expression initiates colonic tumorigenesis from cells outside the stem cell niche

Hereditary mixed polyposis syndrome (HMPS) is characterized by the development of mixed-morphology colorectal tumors and is caused by a 40-kb genetic duplication that results in aberrant epithelial expression of the gene encoding mesenchymal bone morphogenetic protein antagonist, GREM1. Here we use HMPS tissue and a mouse model of the disease to show that epithelial GREM1 disrupts homeostatic intestinal morphogen gradients, altering cell fate that is normally determined by position along the vertical epithelial axis. This promotes the persistence and/or reacquisition of stem cell properties in Lgr5-negative progenitor cells that have exited the stem cell niche. These cells form ectopic crypts, proliferate, accumulate somatic mutations and can initiate intestinal neoplasia, indicating that the crypt base stem cell is not the sole cell of origin of colorectal cancer. Furthermore, we show that epithelial expression of GREM1 also occurs in traditional serrated adenomas, sporadic premalignant lesions with a hitherto unknown pathogenesis, and these lesions can be considered the sporadic equivalents of HMPS polyps.

Abstract 2873: A molecular signature predictive of indolent prostate cancer

With more than 230,000 estimated new cases in 2013, prostate cancer represents the most commonly diagnosed cancer in American men. While a subgroup of patients will develop an aggressive and lethal prostate cancer, most present with a low-risk form of the disease that requires little or no treatment. It is therefore crucial to distinguish patients whose tumors are likely to progress to aggressive disease from those whose tumors will remain indolent and for whom treatment may be more detrimental than beneficial.

In our recent study, we hypothesized that low Gleason score prostate tumors can be distinguished as indolent and aggressive based on expression of genes associated with aging and senescence (1). Using gene set enrichment analyses and a decision tree learning model, we identified a 3-gene panel_FGFR1, PMP22, and CDKN1A_that is enriched in indolent prostate cancers and accurately predicts outcome of low Gleason score tumors at both the RNA and protein levels. In particular, protein expression of this 3-gene panel in biopsy samples correctly distinguished Gleason 6 patients who failed active surveillance over a 10-year period.

Following from our initial study, our current efforts are focused on exploiting this 3-gene panel to develop a robust clinical assay for distinguishing indolent and aggressive tumors. We are currently using qRT-PCR, immunofluorescence, and immunohistochemistry assays to assess the most effective way to quantify the simultaneous expression of the 3-gene panel in low Gleason score tumor biopsies/tissues. This quantitative assay will ultimately be applied to a large cohort study assessing the predictive power of the 3-gene signature in patients under active surveillance. We envision that such a prognostic test will significantly improve our ability to predict the outcome of patients with low Gleason score tumors and facilitate appropriate decisions of treatment for men under active surveillance.

1. Irshad S, et al. (2013) A molecular signature predictive of indolent prostate cancer. Science translational medicine 5(202):202ra122.

Citation Format: Shazia Irshad, Mukesh Bansal, Clementine Le Magnen, Risham Dillon, Mireia Castillo-Martin, Tian Zheng, Alvaro Aytes, Sven Wenske, Paolo Guarnieri, Pavel Sumazin, Mitchell Benson, Michael M. Shen, Andrea Califano, Cory Abate-Shen. A molecular signature predictive of indolent prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2873. doi:10.1158/1538-7445.AM2014-2873

A molecular signature predictive of indolent prostate cancer

Many newly diagnosed prostate cancers present as low Gleason score tumors that require no treatment intervention. Distinguishing the many indolent tumors from the minority of lethal ones remains a major clinical challenge. We now show that low Gleason score prostate tumors can be distinguished as indolent and aggressive subgroups on the basis of their expression of genes associated with aging and senescence. Using gene set enrichment analysis, we identified a 19-gene signature enriched in indolent prostate tumors. We then further classified this signature with a decision tree learning model to identify three genes--FGFR1, PMP22, and CDKN1A--that together accurately predicted outcome of low Gleason score tumors. Validation of this three-gene panel on independent cohorts confirmed its independent prognostic value as well as its ability to improve prognosis with currently used clinical nomograms. Furthermore, protein expression of this three-gene panel in biopsy samples distinguished Gleason 6 patients who failed surveillance over a 10-year period. We propose that this signature may be incorporated into prognostic assays for monitoring patients on active surveillance to facilitate appropriate courses of treatment.

The use of molecular imaging combined with genomic techniques to understand the heterogeneity in cancer metastasis

Tumour heterogeneity has, in recent times, come to play a vital role in how we understand and treat cancers; however, the clinical translation of this has lagged behind advances in research. Although significant advancements in oncological management have been made, personalized care remains an elusive goal. Inter- and intratumour heterogeneity, particularly in the clinical setting, has been difficult to quantify and therefore to treat. The histological quantification of heterogeneity of tumours can be a logistical and clinical challenge. The ability to examine not just the whole tumour but also all the molecular variations of metastatic disease in a patient is obviously difficult with current histological techniques. Advances in imaging techniques and novel applications, alongside our understanding of tumour heterogeneity, have opened up a plethora of non-invasive biomarker potential to examine tumours, their heterogeneity and the clinical translation. This review will focus on how various imaging methods that allow for quantification of metastatic tumour heterogeneity, along with the potential of developing imaging, integrated with other in vitro diagnostic approaches such as genomics and exosome analyses, have the potential role as a non-invasive biomarker for guiding the treatment algorithm.

Assessment of microtubule-associated protein (MAP)-Tau expression as a predictive and prognostic marker in TACT; a trial assessing substitution of sequential docetaxel for FEC as adjuvant chemotherapy for early breast cancer

The TACT trial is the largest study assessing the benefit of taxanes as part of adjuvant therapy for early breast cancer. The goal of this translational study was to clarify the predictive and prognostic value of Tau within the TACT trial. Tissue microarrays (TMA) were available from 3,610 patients. ER, PR, HER2 from the TACT trial and Tau protein expression was determined by immunohistochemistry on duplicate TMAs. Two parallel scoring systems were generated for Tau expression ('dichotomised' vs. 'combined' score). The positivity rate of Tau expression was 50 % in the trial population (n = 2,483). Tau expression correlated positively with ER (p < 0.001) and PR status (p < 0.001); but negatively with histological grade (p < 0.001) and HER2 status (p < 0.001). Analyses with either scoring systems for Tau expression demonstrated no significant interaction between Tau expression and efficacy of docetaxel. Contrary to the hypothesis that taxane benefit would be enriched in Tau negative/low patients, the only groups with a suggestion of a reduced event rate in the taxane group were the HER2-positive, Tau positive subgroups. Tau expression was seen to be a prognostic factor on univariate analysis associated with an improved DFS, independent of the treatment group (p < 0.001). It had no prognostic value in ER-negative tumours and the weak prognostic effect of Tau in ER-positive tumours (p = 0.02) diminished, when considering ER as an ordinal variable. On multivariable analyses, Tau had no prognostic value in either group. In addition, no significant interaction between Tau expression and benefit from docetaxel in patients within the PR-positive and negative subsets was seen. This is now the second large adjuvant study, and the first with quantitative analysis of ER and Tau expression, failing to show an association between Tau and taxane benefit with limited utility as a prognostic marker for Tau in ER-positive early breast cancer patients.

Abstract P5-01-01: Lymphoid tissue inducer cells: Identification of a novel immune cell within the breast tumour microenvironment and its role in promoting tumour cell invasion

Within breast cancers, trans-endothelial migration of tumour cells through lymphatic vessels is the first step to tumour dissemination and lympho-vascular invasion has been shown to stratify breast cancer phenotypes into distinct prognostic groups. The exact molecular mechanisms mediating tumor cell entry and persistence within the lymphatic system remain unclear. Lymphoid tissue inducer (LTi) cells are members of the emerging family of retinoic acid related orphan receptor (ROR)gt+ innate lymphoid cells (ILCs), and their interaction with stromal cells induces production by the stromal cells of VEGF-C and “lymphoid” chemokines, essential for lymphoid organogenesis. We hypothesized that tumour cells manipulate the normal processes that govern chemokine-dependent, trans-lymphatic migration of immune cells, including LTi cells; shaping its microenvironment. Results: We analyzed the expression of lymphoid chemokines genes (CXCL12, CXCL13, CCL19, CCL20 and CCL21) and their corresponding receptors (CXCR4, CXCR5, CCR6 and CCR7) within the METABRIC (Molecular Taxonomy of Breast Cancer International Consortium) Tissue Bank. An unsupervised hierarchical cluster analysis revealed co-expression of these genes, categorizing breast tumors as relatively high/low expressors. Tumors exhibiting relatively high expression of these genes were found to be enriched for “basal-like” breast cancers according to PAM50 intrinsic subtype assignments. Immunofluorescence of the primary tumour sections identified cells that were comparable in phenotype to LTi cells. In a blinded study, we observed that patients with high LTi counts within the tumour microenvironment were also likely to have a gene expression corresponding to high expression for the lymphoid chemokines. IHC for the lymphatic marker, podoplanin found that the LTi count correlated with both an increased lymphatic vessel density and tumor invasion into lymphatic vessels. Within the basal and HER2+ve subtypes, patients with more than 4 lymph nodes were found to exhibit higher numbers of intratumoural LTi cells. In vitro studies, alongside multi-photon in vivo imaging were performed to investigate the interaction between intra-tumoural LTi and mesenchymal stromal cells. CXCL13 was shown to be essential for LTi clustering around stromal cells in vitro, and, the administration of a blocking antibody in vivo delayed the onset of lymph node metastasis in a murine mammary tumour (4T1.2) model. CXCLl3 has been identified as having independent prognostic significance in breast cancer, but we and others report that breast cancer cell lines are not the source of CXCL13. We show that an increase in stromal CXCL13 concentration within the tumour microenvironment following LTi recruitment promotes an EMT phenotype in the 4T1.2 cancer cell line, possibly via activation of the RANKL/RANK axis promoting tumorigenesis. We report for the first time, the identification of LTi cells within the human breast cancer tumour microenvironment and propose a pivotal role for these cells, through stromal cell interactions in the tumour microenvironment, in facilitating lymphatic invasion of tumour cells by modulation of the local lymphoid chemokine profile.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-01-01.

Modeling prostate cancer in mice: something old, something new, something premalignant, something metastatic

More than 15 years ago, the first generation of genetically engineered mouse (GEM) models of prostate cancer was introduced. These transgenic models utilized prostate-specific promoters to express SV40 oncogenes specifically in prostate epithelium. Since the description of these initial models, there have been a plethora of GEM models of prostate cancer representing various perturbations of oncogenes or tumor suppressors, either alone or in combination. This review describes these GEM models, focusing on their relevance for human prostate cancer and highlighting their strengths and limitations, as well as opportunities for the future.

BRCA1 mutations and luminal-basal transformation

The multifunctional roles of BRCA1 include its ability to regulate transcriptional processes that control differentiation at multiple levels, as well as functioning as a tumor suppressor. Data herein demonstrate that germline mutations in Brca1 impair luminal cell lineage and mammary development, with its deficiency converting ER-positive luminal tumors into basal-like cancers. Heterozygous mutations in Brca1 lead to downregulation of a number of luminal differentiation genes, explaining how it suppresses basal-like tumors, also highlighting its importance outside of its known highly publicized role in DNA repair.

ERK and AKT signaling drive MED1 overexpression in prostate cancer in association with elevated proliferation and tumorigenicity

MED1 is a key coactivator of the androgen receptor (AR) and other signal-activated transcription factors. Whereas MED1 is overexpressed in prostate cancer cell lines and is thought to coactivate distinct target genes involved in cell-cycle progression and castration-resistant growth, the underlying mechanisms by which MED1 becomes overexpressed and its oncogenic role in clinical prostate cancer have remained unclear. Here, we report that MED1 is overexpressed in the epithelium of clinically localized human prostate cancer patients, which correlated with elevated cellular proliferation. In a Nkx3.1:Pten mutant mouse model of prostate cancer that recapitulates the human disease, MED1 protein levels were markedly elevated in the epithelium of both invasive and castration-resistant adenocarcinoma prostate tissues. Mechanistic evidence showed that hyperactivated ERK and/or AKT signaling pathways promoted MED1 overexpression in prostate cancer cells. Notably, ectopic MED1 overexpression in prostate cancer xenografts significantly promoted tumor growth in nude mice. Furthermore, MED1 expression in prostate cancer cells promoted the expression of a number of novel genes involved in inflammation, cell proliferation, and survival. Together, these findings suggest that elevated MED1 is a critical molecular event associated with prostate oncogenesis.

Proliferation-associated Brn-3b transcription factor can activate cyclin D1 expression in neuroblastoma and breast cancer cells

Brn-3b transcription factor enhances proliferation of neuroblastoma (NB) and breast cancer cell lines in vitro and increases the rate and size of in vivo tumour growth, whereas reducing Brn-3b slows growth, both in vitro and in vivo. Brn-3b is elevated in >65% of breast cancer biopsies, and here we demonstrate that Brn-3b is also elevated in NB tumours. We show a significant correlation between Brn-3b and cyclin D1 (CD1) in breast cancers and NB tumours and cell lines. Brn-3b directly transactivates the CD1 promoter in co-transfection experiments, whereas electrophoretic mobility shift assay and chromatin immunoprecipitation assays demonstrate that Brn-3b protein binds to an octamer sequence located in the proximal CD1 promoter. Site-directed mutagenesis of this sequence resulted in loss of transactivation of the CD1 promoter by Brn-3b. Thus, Brn-3b may act to alter growth properties of breast cancer and NB cells by enhancing CD1 expression in these cells.

Cannabis-induced psychotic-like experiences are predicted by high schizotypy. Confirmation of preliminary results in a large cohort

BACKGROUND

Cannabis use has been identified as a possible risk factor for developing schizophrenia. In a previous paper we reported preliminary evidence that cannabis use increases the likelihood of psychosis-like experiences in non-clinical respondents who scored highly on a measure of schizotypy. We now present findings from pooled data from 3 new follow-up studies comprising a sample of 477 respondents, of whom 332 reported using cannabis at least once.

SAMPLING AND METHODS

As in our previous study, the psychological effects of cannabis were assessed with the Cannabis Experiences Questionnaire, from which 3 subscales can be derived; encompassing pleasurable experiences, psychosis-like experiences and after-effects. The respondents also completed the brief Schizotypal Personality Questionnaire.

RESULTS

Cannabis use was reported by 70% of the sample. Use per se was not significantly related to schizotypy. However, high scoring schizotypes were more likely to report both psychosis-like experiences and unpleasant after-effects associated with cannabis use. The pleasurable effects of cannabis use were not related to schizotypy. Exploratory factor analysis of the pooled data from this study and our previous report (providing a sample of >400 cannabis users) suggested a 3-factor solution. These were characterised as a psychotic-dysphoric index (factor 1), an expansive index (factor 2) and an intoxicated index (factor 3). Schizotypy was highly correlated with factors 1 and 3, though not with factor 2.

CONCLUSION

High scoring schizotypes who use cannabis are more likely to experience psychotic-dysphoric phenomena and intoxicating effects during and after use. Our results confirm and expand the findings reported in our previous study. They are consistent with the hypothesis that cannabis use may be a risk factor for full psychosis in this group.

Localization of a novel autosomal recessive non-syndromic hearing impairment locus DFNB55 to chromosome 4q12-q13.2

Hereditary hearing impairment (HI) is the most genetically heterogeneous trait known in humans. So far, 54 autosomal recessive non-syndromic hearing impairment (ARNSHI) loci have been mapped, and 21 ARNSHI genes have been identified. Here is reported the mapping of a novel ARNSHI locus, DFNB55, to chromosome 4q12-q13.2 in a consanguineous Pakistani family. A maximum multipoint LOD score of 3.5 was obtained at marker D4S2638. The region of homozygosity and the 3-unit support interval are flanked by markers D4S2978 and D4S2367. The region spans 8.2 cm on the Rutgers combined linkage-physical map and contains 11.5 Mb. DFNB55 represents the third ARNSHI locus mapped to chromosome 4.

The Brn-3b transcription factor regulates the growth, behavior, and invasiveness of human neuroblastoma cells in vitro and in vivo

Neuroblastomas are the second most common solid tumor in children but the molecular mechanisms underlying the initiation and progression of this disease are poorly understood. We previously showed that the Brn-3b transcription factor is highly expressed in actively proliferating neuroblastoma cells but is significantly decreased when these cells are induced to differentiate. In this study, we analyzed the effects of manipulating Brn-3b levels in the human neuroblastoma cell line, IMR-32 and showed that constitutive overexpression of Brn-3b consistently increased cellular growth and proliferation in monolayer as well as in an anchorage-independent manner compared with controls whereas stably decreasing Brn-3b can reduce the rate of growth of these cells. Cells with high Brn-3b also fail to respond to growth inhibitory retinoic acid, as they continue to proliferate. Moreover, Brn-3b levels significantly modified tumor growth in vivo with elevated Brn-3b resulting in faster tumor growth in xenograft models whereas decreasing Brn-3b resulted in slower growth compared with controls. Interestingly, elevated Brn-3b levels also enhances the invasive capacity of these neuroblastoma cells with significantly larger numbers of migrating cells observed in overexpressing clones compared with controls. Because invasion and metastasis influence morbidity and mortality in neuroblastoma and so significantly affect the course and outcome of neuroblastomas, this finding is very important. Our results therefore suggest that Brn-3b transcription factor contributes to proliferation of neuroblastoma cells in vivo and in vitro but may also influence progression and/or invasion during tumorigenesis. It is possible that decreasing Brn-3b levels may reverse some effects on growth and proliferation of these cells.

The Brn-3a POU family transcription factor stimulates p53 gene expression in human and mouse tumour cells

The Brn-3a POU family transcription factor is able to induce the expression of genes encoding anti-apoptotic proteins such as Bcl-2 and Bcl-x and protects neuronal cells from apoptosis. This effect is opposed by the pro-apoptotic p53 protein which completely inhibits the ability of Brn-3a to activate the Bcl-2 and Bcl-x promoters. Here we demonstrate that Brn-3a is able to stimulate p53 expression. Thus, in co-transfection experiments, Brn-3a activates the p53 promoter acting via a region from +22 to +67, located between the most proximal (+1) and the most distal (+105) transcriptional start sites. Similarly, reduction of Brn-3a expression using anti-sense constructs reduces endogenous p53 expression in human neuroblastoma or cervical carcinoma cell lines growing in vitro and as tumours in nude mice whilst increasing Brn-3a levels enhances p53 expression. These results suggest the existence of a negative feedback loop in which elevated Brn-3a expression induces the expression of p53 which, in turn, antagonises the anti-apoptotic activity of Brn-3a.

Differential expression of beta1 and beta2 integrins and L-selectin on CD4+ and CD8+ T lymphocytes in human blood: comparative analysis between isolated cells, whole blood samples and cryopreserved preparations

Flow cytometric analysis was used to compare the expression of adhesion molecules on human CD4+ and CD8+ T lymphocytes in isolated blood mononuclear cells (MNCs) in whole blood samples and in cryopreserved MNC preparations. Examination of MNCs revealed that the CD11b and CD11c components of the beta2 integrins were preferentially expressed on CD8+ T cells, whereas CD62L was present on more CD4+ T cells. All CD4+ and CD8+ T lymphocytes were positive for CD11a but the CD8+ population had a higher intensity of expression of CD11a and also CD11b. Virtually identical results were obtained with T cells in whole blood samples. In relation to the beta1 integrins, the only difference between isolated CD4+ and CD8+ T cells was that the latter subset had a greater proportion of cells bearing CD49d. The naive cell marker CD45RA was present on the majority of CD8+ T cells whereas CD45RA and the memory marker CD45RO were evenly distributed within the CD4+ T cell subset. Although cryopreservation of lymphocytes did not modify the expression of beta1 and beta2 integrins it produced a marked reduction in the percentage of CD4+ and CD8+ T cells bearing CD62L. With regard to endothelial interactions, it appears that cryopreserved lymphocytes are suitable for inclusion in studies of integrin-mediated adhesion but not for those relating to tethering or recognition of addressins on high endothelial venules. Differences in adhesion molecule expression between CD4+ and CD8+ T lymphocytes could underlie the selective extravasation of these subsets into sites of infection and inflammation.