Cancer drug sensitivity prediction from routine histology images

Drug sensitivity prediction models can aid in personalising cancer therapy, biomarker discovery, and drug design. Such models require survival data from randomised controlled trials which can be time consuming and expensive. In this proof-of-concept study, we demonstrate for the first time that deep learning can link histological patterns in whole slide images (WSIs) of Haematoxylin & Eosin (H&E) stained breast cancer sections with drug sensitivities inferred from cell lines. We employ patient-wise drug sensitivities imputed from gene expression-based mapping of drug effects on cancer cell lines to train a deep learning model that predicts patients' sensitivity to multiple drugs from WSIs. We show that it is possible to use routine WSIs to predict the drug sensitivity profile of a cancer patient for a number of approved and experimental drugs. We also show that the proposed approach can identify cellular and histological patterns associated with drug sensitivity profiles of cancer patients.

AI-Based Risk Score from Tumour-Infiltrating Lymphocyte Predicts Locoregional-Free Survival in Nasopharyngeal Carcinoma

BACKGROUND

Locoregional recurrence of nasopharyngeal carcinoma (NPC) occurs in 10% to 50% of cases following primary treatment. However, the current main prognostic markers for NPC, both stage and plasma Epstein-Barr virus DNA, are not sensitive to locoregional recurrence.

METHODS

We gathered 385 whole-slide images (WSIs) from haematoxylin and eosin (H&E)-stained NPC sections (n = 367 cases), which were collected from Sun Yat-sen University Cancer Centre. We developed a deep learning algorithm to detect tumour nuclei and lymphocyte nuclei in WSIs, followed by density-based clustering to quantify the tumour-infiltrating lymphocytes (TILs) into 12 scores. The Random Survival Forest model was then trained on the TILs to generate risk score.

RESULTS

Based on Kaplan-Meier analysis, the proposed methods were able to stratify low- and high-risk NPC cases in a validation set of locoregional recurrence with a statically significant result (p < 0.001). This finding was also found in distant metastasis-free survival (p < 0.001), progression-free survival (p < 0.001), and regional recurrence-free survival (p < 0.05). Furthermore, in both univariate analysis (HR: 1.58, CI: 1.13-2.19, p < 0.05) and multivariate analysis (HR:1.59, CI: 1.11-2.28, p < 0.05), we also found that our methods demonstrated a strong prognostic value for locoregional recurrence.

CONCLUSION

The proposed novel digital markers could potentially be utilised to assist treatment decisions in cases of NPC.

A Novel Deep Learning Algorithm for Human Papillomavirus Infection Prediction in Head and Neck Cancers Using Routine Histology Images

The etiology of head and neck squamous cell carcinoma (HNSCC) involves multiple carcinogens, such as alcohol, tobacco, and infection with human papillomavirus (HPV). Because HPV infection influences the prognosis, treatment, and survival of patients with HNSCC, it is important to determine the HPV status of these tumors. In this article, we propose a novel deep learning pipeline for HPV infection status prediction with state-of-the-art performance in HPV detection using only whole-slide images of routine hematoxylin and eosin-stained HNSCC sections. We show that our Digital-HPV score generated from hematoxylin and eosin slides produces statistically significant patient stratifications in terms of overall and disease-specific survival. In addition, quantitative profiling of the spatial tumor microenvironment and analysis of the immune profiles show relatively high levels of lymphocytic infiltration in tumor and tumor-associated stroma. High levels of B cells and T cells and low macrophage levels were also identified in HPV-positive patients compared to HPV-negative patients, confirming different immune response patterns elicited by HPV infection in patients with HNSCC.

Advances in pathogenesis and precision medicine for nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a squamous carcinoma with apparent geographical and racial distribution, mostly prevalent in East and Southeast Asia, particularly concentrated in southern China. The epidemiological trend over the past decades has suggested a substantial reduction in the incidence rate and mortality rate due to NPC. These results may reflect changes in lifestyle and environment, and more importantly, a deeper comprehension of the pathogenic mechanism of NPC, leading to much progress in the preventing, screening, and treating for this cancer. Herein, we present the recent advances on the key signal pathways involved in pathogenesis of NPC, the mechanism of Epstein‐Barr virus (EBV) entry into the cell, and the progress of EBV vaccine and screening biomarkers. We will also discuss in depth the development of various therapeutic approaches including radiotherapy, chemotherapy, surgery, targeted therapy, and immunotherapy. These research advancements have led to a new era of precision medicine in NPC.

The EBV-Encoded Oncoprotein, LMP1, Recruits and Transforms Fibroblasts via an ERK-MAPK-Dependent Mechanism

Latent membrane protein 1 (LMP1), the major oncoprotein encoded by Epstein–Barr virus (EBV), is expressed at widely variable levels in undifferentiated nasopharyngeal carcinoma (NPC) biopsies, fueling intense debate in the field as to the importance of this oncogenic protein in disease pathogenesis. LMP1-positive NPCs are reportedly more aggressive, and in a similar vein, the presence of cancer-associated fibroblasts (CAFs) surrounding “nests” of tumour cells in NPC serve as indicators of poor prognosis. However, there is currently no evidence linking LMP1 expression and the presence of CAFs in NPC. In this study, we demonstrate the ability of LMP1 to recruit fibroblasts in vitro in an ERK-MAPK-dependent mechanism, along with enhanced viability, invasiveness and transformation to a myofibroblast-like phenotype. Taken together, these findings support a putative role for LMP1 in recruiting CAFs to the tumour microenvironment in NPC, ultimately contributing to metastatic disease.

Whole-genome profiling of nasopharyngeal carcinoma reveals viral-host co-operation in inflammatory NF-κB activation and immune escape

Interplay between EBV infection and acquired genetic alterations during nasopharyngeal carcinoma (NPC) development remains vague. Here we report a comprehensive genomic analysis of 70 NPCs, combining whole-genome sequencing (WGS) of microdissected tumor cells with EBV oncogene expression to reveal multiple aspects of cellular-viral co-operation in tumorigenesis. Genomic aberrations along with EBV-encoded LMP1 expression underpin constitutive NF-κB activation in 90% of NPCs. A similar spectrum of somatic aberrations and viral gene expression undermine innate immunity in 79% of cases and adaptive immunity in 47% of cases; mechanisms by which NPC may evade immune surveillance despite its pro-inflammatory phenotype. Additionally, genomic changes impairing TGFBR2 promote oncogenesis and stabilize EBV infection in tumor cells. Fine-mapping of CDKN2A/CDKN2B deletion breakpoints reveals homozygous MTAP deletions in 32-34% of NPCs that confer marked sensitivity to MAT2A inhibition. Our work concludes that NPC is a homogeneously NF-κB-driven and immune-protected, yet potentially druggable, cancer.

O26: SIGMA RECEPTORS IN BREAST CANCER – EXAMINING THEIR LIGAND MEDIATED MECHANISMS OF CANCER CELL DEATH AND POTENTIAL FOR CLINICAL DIAGNOSTICS

Introduction

Sigma receptors (SRs) are regularly overexpressed in cancer however their functions remain unknown. Certain Sigma1-receptor (Sig1R) ligands trigger death in breast cancer (BCa) cells but not in non-cancerous breast cells (NCB). In stressed cells, Sig1R is vital to the pro-survival unfolded protein response (UPR). Cancer cells depend on UPR signalling for survival, investigating Sig1R mediated mechanisms in BCa vs. NCB might uncover novel and targetable weaknesses in cancer.

Method

UPR activation by Sig1R antagonist IPAG was examined in BCa cells by Western blotting. Sig1R and UPR marker localizations were examined by immunofluorescence. SR gene expression between 141 matched breast tumour tissue and tumour adjacent normal samples was compared using RNAseq data from The Cancer Genome Atlas (TCGA). Merged microarray datasets were used to compare SR expression in 399 primary breast tumours with relapse (BCaR) vs. 352 without relapse (BCaNR).

Result

Relative to non-cancerous human mammary epithelial cells, Sig1R expression was lowest in MCF7s and highest in MDA-MB-468s. IPAG induced differential temporal activation of all three branches of the UPR in MCF7 and tamoxifen-resistant, low Sig1R expressing cell line LY2. TCGA RNAseq data highlighted SR overexpression in BCa particularly in the basal subtype. Microarray data showed both oestrogen receptor (ER)+ and ER- BCaR primaries had elevated SIGMAR1 compared to BCaNR primaries of the same respective ER status.

Conclusion

BCa cells are dependent on Sig1R mediated signalling. Sig1R expression might indicate the propensity of breast tumours to relapse. Thus, Sig1R represents a potential target in BCa, particularly for aggressive subtypes.

Take-home message

The Sigma-1 receptor (Sig1R) has a vital but unknown pro-survival function in cancer; Sig1R ligands cause death in cancer cells while sparing non-cancerous ones. Characterizing Sig1R mediated signalling may reveal novel, selective therapeutic targets in cancer.

O12: IHC ANALYSIS OF RESIDUAL DISEASE POST NEOADJUVANT TRASTUZUMAB FOR EARLY STAGE BREAST CANCER REVEALS ER/HER2 CROSSTALK THROUGH INCREASED ER SIGNALLING

Introduction

Therapeutic pressure functionally affects oncogenes and related signalling pathways through dynamic alterations in transcriptional and epigenetic alterations. Altered receptor status occurs throughout tumour progression and may be influenced by adjuvant and neoadjuvant therapies. Recurrent transcriptional remodelling events have been described in the progression of primary breast cancer to metastasis, including increased tyrosine kinase signalling, specifically Her2, and loss of ESR1 gene expression. We hypothesise that in the setting of tyrosine kinase inhibition, an increase in estrogen receptor (ER) signalling is observed.

Method

A database of patients recruited to ICORG trial 07/09 was queried to identify patients with histologically confirmed, Her2-overexpressing or Her2 amplified, nonmetastatic, invasive breast cancer who received neoadjuvant trastuzumab, alone or in combination with neoadjuvant systemic chemotherapy. Clinicopathological characteristics recorded include age at diagnosis, clinical stage, receptor status and percentage positivity, and pathological complete response.

Result

A total of 55 patients identified on ICORG trial 09/07 received neoadjuvant trastuzumab. Of these, 27 achieved a complete pathological response (49%; n=27/55). In those with residual disease, a gain in mean ER staining percentage positivity was observed in the residual disease compared to diagnostic biopsy staining (59.22 vs 45.11; p=0.03). A corresponding loss in Her2 percentage staining positivity was also observed (p=0.006).

Conclusion

An inverse correlation was observed between loss of Her2 positivity and percentage gain in ER staining in patients with residual disease following treatment with neoadjuvant trastuzumab. Further study is needed to elucidate the regulatory mechanism of ER/Her2 crosstalk, which may be epigenetically regulated through DNA methylation.

Take-home message

ER/Her2 crosstalk can be demonstrated clinically in IHC analysis of patients with residual disease post neoadjuvant trastuzumab. Tyrosine kinase inhibition in the form of neoadjuvant trastuzumab results in loss of Her2 signalling and corresponding gain in ER signalling.

O43: CLINICAL IMPACT OF GENE FUSIONS IN BREAST CANCER BRAIN METASTASES

Introduction

The incidence of brain metastases is increasing despite longer survival rates for patients with advanced breast cancer. The identification of novel therapeutic targets for these patients is an urgent unmet clinical need. Sequencing of metastatic tumours have largely focused on mutations however gene fusions have an important, yet underappreciated role in tumorigenesis and disease progression. In this study, we investigate the role of gene fusions in brain metastatic disease and their impact on altered therapeutic responses.

Method

RNA sequencing was performed on the largest reported cohort of patient matched primary and resected brain metastatic tumours (45 patients n=90 samples). Expressed gene fusions were detected computationally using STAR-Fusion and Arriba.

Result

We identified differential gene fusion burden in brain metastatic tumours (medium of 58) vs. primary breast tumours (medium of 38) (p &lt; 0.05). Enrichment for fusions in pathways associated with tumour cell plasticity and proliferation with recurrent fusions in known cancer driver genes related to MAPK, HER signaling identified. Of note, a fusion in CDK12 is of clinical importance. Increased genomic alterations and over expression of CDK12 is associated with brain metastases free survival in an independent cohort of primary breast tumours with a recorded history of brain metastases. It has been proposed that inhibition of CDK12 may induce BRCAness in tumours making them sensitive to PARP inhibition.

Conclusion

These results highlight the significant role of gene fusions in breast cancer brain metastases.

Abbreviations

MAPK Mitogen Activated Protein Kinase, HER Human Epidermal Receptor, CDK12 Cyclin Dependent Kinase 12

Take-home message

We highlight the significant role of gene fusions in breast cancer brain metastases and offer specific actionable genomic alterations to be exploited.

The Role of EBV-Encoded LMP1 in the NPC Tumor Microenvironment: From Function to Therapy

Nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) infection. It is also characterized by heavy infiltration with non-malignant leucocytes. The EBV-encoded latent membrane protein 1 (LMP1) is believed to play an important role in NPC pathogenesis by virtue of its ability to activate multiple cell signaling pathways which collectively promote cell proliferation and survival, angiogenesis, invasiveness, and aerobic glycolysis. LMP1 also affects cell-cell interactions, antigen presentation, and cytokine and chemokine production. Here, we discuss how LMP1 modulates local immune responses that contribute to the establishment of the NPC tumor microenvironment. We also discuss strategies for targeting the LMP1 protein as a novel therapy for EBV-driven malignancies.

Single-cell transcriptomic analysis defines the interplay between tumor cells, viral infection, and the microenvironment in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-associated malignancy with a complex tumor ecosystem. How the interplay between tumor cells, EBV, and the microenvironment contributes to NPC progression and immune evasion remains unclear. Here we performed single-cell RNA sequencing on ~104,000 cells from 19 EBV⁺ NPCs and 7 nonmalignant nasopharyngeal biopsies, simultaneously profiling the transcriptomes of malignant cells, EBV, stromal and immune cells. Overall, we identified global upregulation of interferon responses in the multicellular ecosystem of NPC. Notably, an epithelial-immune dual feature of malignant cells was discovered and associated with poor prognosis. Functional experiments revealed that tumor cells with this dual feature exhibited a higher capacity for tumorigenesis. Further characterization of the cellular components of the tumor microenvironment (TME) and their interactions with tumor cells revealed that the dual feature of tumor cells was positively correlated with the expression of co-inhibitory receptors on CD8⁺ tumor-infiltrating T cells. In addition, tumor cells with the dual feature were found to repress IFN-γ production by T cells, demonstrating their capacity for immune suppression. Our results provide new insights into the multicellular ecosystem of NPC and offer important clinical implications.

The Epstein-Barr Virus-Encoded EBNA1 Protein Activates the Bone Morphogenic Protein (BMP) Signalling Pathway to Promote Carcinoma Cell Migration

The Epstein-Barr virus (EBV)-encoded nuclear antigen 1 (EBNA1) protein is expressed in all virus-associated malignancies, where it performs an essential role in the maintenance, replication and transcription of the EBV genome. In recent years, it has become apparent that EBNA1 can also influence cellular gene transcription. Here, we demonstrate that EBNA1 is able to stimulate the expression of the Transforming growth factor-beta (TGFβ) superfamily member, bone morphogenic protein 2 (BMP2), with consequential activation of the BMP signalling pathway in carcinoma cell lines. We show that BMP pathway activation is associated with an increase in the migratory capacity of carcinoma cells, an effect that can be ablated by the BMP antagonist, Noggin. Gene expression profiling of authentic EBV-positive nasopharyngeal carcinoma (NPC) tumours revealed the consistent presence of BMP ligands, established BMP pathway effectors and putative target genes, constituting a prominent BMP “signature” in this virus-associated cancer. Our findings show that EBNA1 is the major viral-encoded protein responsible for activating the BMP signalling pathway in carcinoma cells and supports a role for this pathway in promoting cell migration and possibly, metastatic spread.

Strategies for conjugating iridium(III) anticancer complexes to targeting peptides via copper-free click chemistry

We report the synthesis and characterization of novel pentamethylcyclopentadienyl (Cp*) iridium(III) complexes [(Cp*)Ir(4-methyl-4'-carboxy-2,2'-bipyridine)Cl]PF6 (Ir-I), the product (Ir-II) from amide coupling of Ir-I to dibenzocyclooctyne-amine, and its conjugate (Ir-CP) with the cyclic nona-peptide c(CRWYDENAC). The familiar three-legged 'piano-stool' configuration for complex Ir-I was confirmed by its single crystal X-ray structure. Significantly, copper-free click strategy has been developed for site-specific conjugation of the parent complex Ir-I to the tumour targeting nona-cyclic peptide. The approach consisted of two steps: (i) the carboxylic acid group of the bipyridine ligand in complex Ir-I was first attached to an amine functionalized dibenzocyclooctyne group via amide formation to generate complex Ir-II; and (ii) the alkyne bond of dibenzocyclooctyne in complex Ir-II underwent a subsequent strain-promoted copper-free cycloaddition with the azide group of the modified peptide. Interestingly, while complex Ir-I was inactive towards A2780 human ovarian cancer cells, complex Ir-II exhibited moderate cytotoxic activity. Targeted complexes such as Ir-CP offer scope for enhanced activity and selectivity of this class of anticancer complexes.

CD40L membrane retention enhances the immunostimulatory effects of CD40 ligation

In carcinomas, the nature of CD40 ligand shapes the outcome of CD40 ligation. To date, the consequences of membrane-bound CD40L (mCD40L) on its immune-stimulatory function are unknown. Here, we examined the impact of mCD40L versus soluble CD40L (sCD40L) on T24 bladder carcinoma gene expression profiling. Of 410 differentially expressed genes, 286 were upregulated and 124 downregulated by mCD40L versus sCD40L. Gene ontology enrichment analysis revealed immune-stimulatory function as the most significant enriched biological process affected by upregulated transcripts, while those downregulated were critical for cell growth and division. Furthermore, immature dendritic cells (iDC) responded to mCD40L with enhanced maturation and activation over sCD40L evidenced by higher expression levels of CD83, CD86, HLA-DR and CD54, increased secretion of IL12 and IL10 and higher tumour-antigen (TA) uptake capacity. Furthermore, autologus CD3+ T cells responded to TA-loaded mCD40L-activated DC with increased proliferation and cytotoxic response (CD107a and IFN-γ-producing CD3+ CD8+ T cells) to the tumour-loaded autologous PBMCs compared to sCD40L. Thus, these data indicate that mCD40L enhances the immunostimulatory capacity over sCD40L. Furthermore, the ability of mCD40L to also directly induce cell death in CD40-expressing carcinomas, subsequently releasing tumour-specific antigens into the tumour microenvironment highlights the potential for mCD40L as a multi-faceted anti-cancer immunotherapeutic.

Discovery of selective, antimetastatic and anti-cancer stem cell metallohelices via post-assembly modification

A remarkable array of mechanistic and pharmacological behaviours is discovered via click derivatisation of asymmetric, optically pure helicate-like compounds.

Helicates and related metallofoldamers, synthesised by dynamic self-assembly, represent an area of chemical space inaccessible by traditional organic synthesis, and yet with potential for discovery of new classes of drug. Here we report that water-soluble, optically pure Fe(ii)- and even Zn(ii)-based triplex metallohelices are an excellent platform for post-assembly click reactions. By these means, the in vitro anticancer activity and most importantly the selectivity of a triplex metallohelix Fe(ii) system are dramatically improved. For one compound, a remarkable array of mechanistic and pharmacological behaviours is discovered: inhibition of Na⁺/K⁺ ATPase with potency comparable to the drug ouabain, antimetastatic properties (including inhibition of cell migration, re-adhesion and invasion), cancer stem cell targeting, and finally colonosphere inhibition competitive with the drug salinomycin.

Photoactive platinum(iv) complex conjugated to a cancer-cell-targeting cyclic peptide

Conjugate of a cancer-cell targeting cyclic peptide with a photoactive platinum(iv) complex exhibits enhanced photocytotoxicity and cell accumulation.

Activation of sterol regulatory element-binding protein 1 (SREBP1)-mediated lipogenesis by the Epstein-Barr virus-encoded latent membrane protein 1 (LMP1) promotes cell proliferation and progression of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) infection. The EBV-encoded latent membrane protein 1 (LMP1), which is commonly expressed in NPC, engages multiple signaling pathways that promote cell growth, transformation, and metabolic reprogramming. Here, we report a novel function of LMP1 in promoting de novo lipogenesis. LMP1 increases the expression, maturation and activation of sterol regulatory element-binding protein 1 (SREBP1), a master regulator of lipogenesis, and its downstream target fatty acid synthase (FASN). LMP1 also induces de novo lipid synthesis and lipid droplet formation. In contrast, small interfering RNA (siRNA) knockdown of LMP1 in EBV-infected epithelial cells diminished SREBP1 activation and lipid biosynthesis. Furthermore, inhibition of the mammalian target of rapamycin (mTOR) pathway, through the use of either mTOR inhibitors or siRNAs, significantly reduced LMP1-mediated SREBP1 activity and lipogenesis, indicating that LMP1 activation of the mTOR pathway is required for SREBP1-mediated lipogenesis. In primary NPC tumors, FASN overexpression is common, with high levels correlating significantly with LMP1 expression. Moreover, elevated FASN expression was associated with aggressive disease and poor survival in NPC patients. Luteolin and fatostatin, two inhibitors of lipogenesis, suppressed lipogenesis and proliferation of nasopharyngeal epithelial cells, effects that were more profound in cells expressing LMP1. Luteolin and fatostatin also dramatically inhibited NPC tumor growth in vitro and in vivo. Our findings demonstrate that LMP1 activation of SREBP1-mediated lipogenesis promotes tumor cell growth and is involved in EBV-driven NPC pathogenesis. Our results also reveal the therapeutic potential of utilizing lipogenesis inhibitors in the treatment of locally advanced or metastatic NPC. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

EBV-encoded miRNAs target ATM-mediated response in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a highly invasive epithelial malignancy that is prevalent in southern China and Southeast Asia. It is consistently associated with latent Epstein-Barr virus (EBV) infection. In NPC, miR-BARTs, the EBV-encoded miRNAs derived from BamH1-A rightward transcripts, are abundantly expressed and contribute to cancer development by targeting various cellular and viral genes. In this study, we establish a comprehensive transcriptional profile of EBV-encoded miRNAs in a panel of NPC patient-derived xenografts and an EBV-positive NPC cell line by small RNA sequencing. Among the 40 miR-BARTs, predominant expression of 22 miRNAs was consistently detected in these tumors. Among the abundantly expressed EBV-miRNAs, BART5-5p, BART7-3p, BART9-3p, and BART14-3p could negatively regulate the expression of a key DNA double-strand break (DSB) repair gene, ataxia telangiectasia mutated (ATM), by binding to multiple sites on its 3'-UTR. Notably, the expression of these four miR-BARTs represented more than 10% of all EBV-encoded miRNAs in tumor cells, while downregulation of ATM expression was commonly detected in all of our tested sequenced samples. In addition, downregulation of ATM was also observed in primary NPC tissues in both qRT-PCR (16 NP and 45 NPC cases) and immunohistochemical staining (35 NP and 46 NPC cases) analysis. Modulation of ATM expression by BART5-5p, BART7-3p, BART9-3p, and BART14-3p was demonstrated in the transient transfection assays. These findings suggest that EBV uses miRNA machinery as a key mechanism to control the ATM signaling pathway in NPC cells. By suppressing these endogenous miR-BARTs in EBV-positive NPC cells, we further demonstrated the novel function of miR-BARTs in inhibiting Zta-induced lytic reactivation. These findings imply that the four viral miRNAs work co-operatively to modulate ATM activity in response to DNA damage and to maintain viral latency, contributing to the tumorigenesis of NPC. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Abstract P4-04-13: Androstenedione initiates rapid non-genomic signalling mediated by cytoplasmic androgen receptor in aromatase inhibitor resistant breast cancer

Aromatase inhibitors (AI) are the recommended first line therapy used to treat postmenopausal breast cancer. These compounds work by inhibiting the aromatase enzyme thus preventing the conversion of circulating androgens to estrogen; as a consequence they alter the tumour intracrinology and create an unopposed highly androgenic steroid environment.

We have previously reported androgen receptor (AR) protein levels to be up-regulated in an AI resistant cell line (LetR cells), and subsequently identified a mechanism by which AR drives a more aggressive phenotype in AI resistant breast cancer [1]. In this current study, LetR cells are shown to be responsive to the weak androgen androstenedione (4AD), and treatment with this steroid drives an invasive phenotype in vitro. In support of this data, clinical studies have also reported increases in the serum levels of 4AD in patients that recur on AI therapy [2].

In the canonical pathway, androgens bind to the AR which results in a conformational change to an active state. Non-canonical AR activation occurs when ligand-transformed AR interacts with molecular partners within the cytosol to induce rapid intracellular signalling cascades. These events do not depend upon AR mediated gene transcription and occur extremely quickly within a manner of minutes [3]. In vitro studies using western blot analysis and co-localisation experiments have indicated 4AD treatment potentiates a resistant phenotype through non-genomic AR actions initiated by rapid second messenger signalling within the cytoplasm. Mass spectrometry (LC–MS/MS) analysis has identified androgen-mediated, rapid cytoplasmic AR protein interactions, resulting in the identification of AR partners unique to our resistant model. Of note, evaluation of AR protein and p-ERK1/2 in a cohort of primary breast cancer patients (n=363) demonstrated that high levels of cytoplasmic AR significantly diminished survival in ER+ PR- patients (p=0.023, Fisher's exact). Elevated pERK1/2 when concomitant with increased levels of cytoplasmic AR result in a significant decrease in the period of disease free survival (p=0.018). Further investigations into these AR interactors will help elucidate mechanisms of resistance to AI therapy, and in turn these novel AR protein partners will aid the identification of patients who would benefit from anti-AR therapy.

References

1. Ali, A., et al., Prosaposin activates the androgen receptor and potentiates resistance to endocrine treatment in breast cancer. Breast Cancer Research : BCR, 2015. 17(1): p. 123.

2. Elliott, K.M., et al., Effects of aromatase inhibitors and body mass index on steroid hormone levels in women with early and advanced breast cancer. British Journal of Surgery, 2014. 101(8): p. 939-948.

3. Foradori, C.D., M.J. Weiser, and R.J. Handa, Non-genomic actions of androgens. Front Neuroendocrinol, 2008. 29(2): p. 169-81.

Citation Format: Bleach RM, Creevey L, Hill ADK, Madden S, Young LS, Pennington SR, McIlroy M. Androstenedione initiates rapid non-genomic signalling mediated by cytoplasmic androgen receptor in aromatase inhibitor resistant breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-04-13.

The role of metabolic reprogramming in γ-herpesvirus-associated oncogenesis

The γ-herpesviruses, EBV and KSHV, are closely associated with a number of human cancers. While the signal transduction pathways exploited by γ-herpesviruses to promote cell growth, survival and transformation have been reported, recent studies have uncovered the impact of γ-herpesvirus infection on host cell metabolism. Here, we review the mechanisms used by γ-herpesviruses to induce metabolic reprogramming in host cells, focusing on their ability to modulate the activity of metabolic regulators and manipulate metabolic pathways. While γ-herpesviruses alter metabolic phenotypes as a means to support viral infection and long-term persistence, this modulation can inadvertently contribute to cancer development. Strategies that target deregulated metabolic phenotypes induced by γ-herpesviruses provide new opportunities for therapeutic intervention.

Abstract P3-04-03: S100β as a predictive biomarker and monitoring tool in endocrine resistant breast cancer

In estrogen receptor positive breast cancer, endocrine therapy is the standard line of treatment and even though it results in reduced recurrence and mortality, a significant number of patients will eventually relapse. Early detection of metastatic disease would significantly enhance management of endocrine resistant breast cancer. Here we investigate the potential of the calcium-binding protein S100β as a predictive biomarker and monitoring tool in endocrine treated patients. Furthermore, the efficacy of S100β inhibition as therapy in patients that fail first line endocrine therapy was examined.

Primary tumor tissue expression of S100β protein was assessed in a retrospective cohort of endocrine treated breast cancer patients. Expression of S100β indicated a significant reduction in time to disease recurrence (n=509, Wilcoxon p&lt;0.0001, hazard ratio 2.43, 95% C.I. is 1.607 to 3.69, p&lt;0.0001, Cox proportional hazard model).

S100β protein is also detectable in serum of breast cancer patients and elevated levels of serum S100β prior to removal of primary tumor is associated with poor disease free survival in endocrine treated patients (n=190, Wilcoxon p=0.0367, hazard ratio 2.68, 95% C.I. is 1.12 to 6.41, p=0.026, Cox proportional hazard model). Serum levels of S100β are significantly reduced after primary tumor resection (n=19, p=0.0003). In serial samples taken during the treatment period, elevated levels of S100β significantly associated with disease progression and with the emergence of metastatic disease (p=0.0031).

In an in-vivo model of endocrine resistant breast cancer, raised levels of S100β marked the emergence of disease progression. The oncogene steroid receptor co-activator 1 (SRC1) and its interaction with homeobox protein (HOXC11) regulates S100β production in a src-kinase dependent manner. Here, src-kinase inhibition reduced tumor burden with a concomitant reduction in serum S100β. We also observed a marked reduction in expression of proliferative marker Ki67 and S100β protein following the treatment of endocrine resistant patient tumor explants with src-kinase inhibitor.

Associations between elevated levels of serum S100β and subsequent disease progression in endocrine treated patients, suggests S100β as a monitoring tool for early detection of disease progression. Additionally high level of S100β can be used as a potential companion diagnostic tool for stratifying patients on endocrine therapy suitable for treatment with small molecule src-kinase inhibitor.

Citation Format: Charmsaz S, Hughes É, Byrne C, Bane F, Tibbitts P, McIlroy M, Hill AD, Young LS. S100β as a predictive biomarker and monitoring tool in endocrine resistant breast cancer [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 P3-04-03.

Epstein-Barr virus: more than 50 years old and still providing surprises

It is more than 50 years since the Epstein-Barr virus (EBV), the first human tumour virus, was discovered. EBV has subsequently been found to be associated with a diverse range of tumours of both lymphoid and epithelial origin. Progress in the molecular analysis of EBV has revealed fundamental mechanisms of more general relevance to the oncogenic process. This Timeline article highlights key milestones in the 50-year history of EBV and discusses how this virus provides a paradigm for exploiting insights at the molecular level in the diagnosis, treatment and prevention of cancer.

The Epstein-Barr virus encoded LMP1 oncoprotein modulates cell adhesion via regulation of activin A/TGFβ and β1 integrin signalling

Approximately 20% of global cancer incidence is causally linked to an infectious agent. Epstein-Barr virus (EBV) accounts for around 1% of all virus-associated cancers and is associated with nasopharyngeal carcinoma (NPC). Latent membrane protein 1 (LMP1), the major oncoprotein encoded by EBV, behaves as a constitutively active tumour necrosis factor (TNF) receptor activating a variety of signalling pathways, including the three classic MAPKs (ERK-MAPK, p38 MAPK and JNK/SAPK). The present study identifies novel signalling properties for this integral membrane protein via the induction and secretion of activin A and TGFβ1, which are both required for LMP1’s ability to induce the expression of the extracellular matrix protein, fibronectin. However, it is evident that LMP1 is unable to activate the classic Smad-dependent TGFβ signalling pathway, but rather elicits its effects through the non-Smad arm of TGFβ signalling. In addition, there is a requirement for JNK/SAPK signalling in LMP1-mediated fibronectin induction. LMP1 also induces the expression and activation of the major fibronectin receptor, α5β1 integrin, an effect that is accompanied by increased focal adhesion formation and turnover. Taken together, these findings support the putative role for LMP1 in the pathogenesis of NPC by contributing to the metastatic potential of epithelial cells.

Epstein-Barr virus at 50-future perspectives

The special November and December issues of the Chinese Journal of Cancer celebrate the 50th anniversary of the discovery of Epstein-Barr virus (EBV) with a series of reviews covering the association of the virus with various cancers, with special emphasis on the role of EBV in the pathogenesis of nasopharyngeal cancer (NPC). The restricted geographic prevalence of NPC along with the tumor's consistent association with EBV infection has fascinated scientists and clinicians ever since it was first suggested in 1966. As in all cancers, NPC development reflects the complex interplay between host genes and environmental factors, but the essential role of EBV infection provides important insight into the etiology of this tumor. Indeed, it is this understanding that is now translating into exciting diagnostic and therapeutic opportunities.

Activation of the FGFR1 signalling pathway by the Epstein-Barr virus-encoded LMP1 promotes aerobic glycolysis and transformation of human nasopharyngeal epithelial cells

Non-keratinizing nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) infection. The EBV-encoded latent membrane protein 1 (LMP1) is believed to play an important role in NPC pathogenesis by virtue of its ability to activate multiple cell signalling pathways which collectively promote cell proliferation, transformation, angiogenesis, and invasiveness, as well as modulation of energy metabolism. In this study, we report that LMP1 increases cellular uptake of glucose and glutamine, enhances LDHA activity and lactate production, but reduces pyruvate kinase activity and pyruvate concentrations. LMP1 also increases the phosphorylation of PKM2, LDHA, and FGFR1, as well as the expression of PDHK1, FGFR1, c-Myc, and HIF-1α, regardless of oxygen availability. Collectively, these findings suggest that LMP1 promotes aerobic glycolysis. With respect to FGFR1 signalling, LMP1 not only increases FGFR1 expression, but also up-regulates FGF2, leading to constitutive activation of the FGFR1 signalling pathway. Furthermore, two inhibitors of FGFR1 (PD161570 and SU5402) attenuate LMP1-mediated aerobic glycolysis, cellular transformation (proliferation and anchorage-independent growth), cell migration, and invasion in nasopharyngeal epithelial cells, identifying FGFR1 signalling as a key pathway in LMP1-mediated growth transformation. Immunohistochemical staining revealed that high levels of phosphorylated FGFR1 are common in primary NPC specimens and that this correlated with the expression of LMP1. In addition, FGFR1 inhibitors suppress cell proliferation and anchorage-independent growth of NPC cells. Our current findings demonstrate that LMP1-mediated FGFR1 activation contributes to aerobic glycolysis and transformation of epithelial cells, thereby implicating FGF2/FGFR1 signalling activation in the EBV-driven pathogenesis of NPC.

Abstract LB-093: Activation of the FGFR1 signaling pathway by the epstein-barr virus-encoded LMP1 promotes aerobic glycolysis and transformation of human nasopharyngeal epithelial cells

Undifferentiated nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) latent infection. The EBV-encoded latent membrane protein 1 (LMP1) oncogene is believed to be important in NPC pathogenesis by virtue of its ability to activate multiple cell signaling pathways to induce proliferation, transformation, angiogenesis and invasiveness as well as modulation of energy metabolism. In this study, we report that LMP1 increases cell uptake of glucose and glutamine, enhances LDHA activity and lactate production, but reduces pyruvate kinase activity and pyruvate concentration. LMP1 also increases the phosphorylation of PKM2, LDHA and FGFR1 as well as expression of PDHK1, FGFR1, c-Myc and HIF-1α regardless of oxygen availability. This suggests that LMP1 promotes aerobic glycolysis. In addition to FGFR1, LMP1 also upregulates FGF2, the FGFR1 ligand, setting up a constitutive activation loop of FGFR1 signaling to promote aerobic glycolysis. FGFR1 inhibitors also abolish LMP1-mediated cellular transformation (proliferation and anchorage-independent growth) as well as cell migration and invasion in nasopharyngeal epithelial cells. Immunohistochemical staining revealed that a high level of phosphorylated FGFR1 is common in primary NPC specimens, and that this correlated with the expression of LMP1. Inhibition of FGFR1 activity in NPC cells results in the suppression of cell proliferation and anchorage-independent growth. Our current findings demonstrate that LMP1-mediated FGFR1 activation contributes to growth and transformation of epithelial cells, thereby implicating FGF2/FGFR1 signaling activation in the EBV-driven pathogenesis of NPC.

Citation Format: Kwok Fung Lo, Christopher W Dawson, Lawrence S Young, Kwok Wai Lo. Activation of the FGFR1 signaling pathway by the epstein-barr virus-encoded LMP1 promotes aerobic glycolysis and transformation of human nasopharyngeal epithelial cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-093. doi:10.1158/1538-7445.AM2015-LB-093

Genomic interaction between ER and HMGB2 identifies DDX18 as a novel driver of endocrine resistance in breast cancer cells

Breast cancer resistance to endocrine therapies such as tamoxifen and aromatase inhibitors is a significant clinical problem. Steroid receptor coactivator-1 (SRC-1), a coregulatory protein of the oestrogen receptor (ER), has previously been shown to have a significant role in the progression of breast cancer. The chromatin protein high mobility group box 2 (HMGB2) was identified as an SRC-1 interacting protein in the endocrine-resistant setting. We investigated the expression of HMGB2 in a cohort of 1068 breast cancer patients and found an association with increased disease-free survival time in patients treated with endocrine therapy. However, it was also verified that HMGB2 expression could be switched on in endocrine-resistant tumours from breast cancer patients. To explore the function of this poorly characterized protein, we performed HMGB2 ChIPseq and found distinct binding patterns between the two contexts. In the resistant setting, the HMGB2, SRC-1 and ER complex are enriched at promoter regions of target genes, with bioinformatic analysis indicating a switch in binding partners between the sensitive and resistant phenotypes. Integration of binding and gene expression data reveals a concise set of target genes of this complex including the RNA helicase DDX18. Modulation of DDX18 directly affects growth of tamoxifen-resistant cells, suggesting that it may be a critical downstream effector of the HMGB2:ER complex. This study defines HMGB2 interactions with the ER complex at specific target genes in the tamoxifen-resistant setting.

Genome diversity of Epstein-Barr virus from multiple tumor types and normal infection

Epstein-Barr virus (EBV) infects most of the world's population and is causally associated with several human cancers, but little is known about how EBV genetic variation might influence infection or EBV-associated disease. There are currently no published wild-type EBV genome sequences from a healthy individual and very few genomes from EBV-associated diseases. We have sequenced 71 geographically distinct EBV strains from cell lines, multiple types of primary tumor, and blood samples and the first EBV genome from the saliva of a healthy carrier. We show that the established genome map of EBV accurately represents all strains sequenced, but novel deletions are present in a few isolates. We have increased the number of type 2 EBV genomes sequenced from one to 12 and establish that the type 1/type 2 classification is a major feature of EBV genome variation, defined almost exclusively by variation of EBNA2 and EBNA3 genes, but geographic variation is also present. Single nucleotide polymorphism (SNP) density varies substantially across all known open reading frames and is highest in latency-associated genes. Some T-cell epitope sequences in EBNA3 genes show extensive variation across strains, and we identify codons under positive selection, both important considerations for the development of vaccines and T-cell therapy. We also provide new evidence for recombination between strains, which provides a further mechanism for the generation of diversity. Our results provide the first global view of EBV sequence variation and demonstrate an effective method for sequencing large numbers of genomes to further understand the genetics of EBV infection.

IMPORTANCE

Most people in the world are infected by Epstein-Barr virus (EBV), and it causes several human diseases, which occur at very different rates in different parts of the world and are linked to host immune system variation. Natural variation in EBV DNA sequence may be important for normal infection and for causing disease. Here we used rapid, cost-effective sequencing to determine 71 new EBV sequences from different sample types and locations worldwide. We showed geographic variation in EBV genomes and identified the most variable parts of the genome. We identified protein sequences that seem to have been selected by the host immune system and detected variability in known immune epitopes. This gives the first overview of EBV genome variation, important for designing vaccines and immune therapy for EBV, and provides techniques to investigate relationships between viral sequence variation and EBV-associated diseases.

Epstein-Barr virus and nasopharyngeal carcinoma

Since its discovery 50 years ago, Epstein-Barr virus (EBV) has been linked to the development of cancers originating from both lymphoid and epithelial cells. Approximately 95% of the world's population sustains an asymptomatic, life-long infection with EBV. The virus persists in the memory B-cell pool of normal healthy individuals, and any disruption of this interaction results in virus-associated B-cell tumors. The association of EBV with epithelial cell tumors, specifically nasopharyngeal carcinoma (NPC) and EBV-positive gastric carcinoma (EBV-GC), is less clear and is currently thought to be caused by the aberrant establishment of virus latency in epithelial cells that display premalignant genetic changes. Although the precise role of EBV in the carcinogenic process is currently poorly understood, the presence of the virus in all tumor cells provides opportunities for developing novel therapeutic and diagnostic approaches. The study of EBV and its role in carcinomas continues to provide insight into the carcinogenic process that is relevant to a broader understanding of tumor pathogenesis and to the development of targeted cancer therapies.

Epstein-Barr virus induction of the Hedgehog signalling pathway imposes a stem cell phenotype on human epithelial cells

Nasopharyngeal carcinoma (NPC) is a cancer common in southern China and South East Asia that is causally linked to Epstein-Barr virus (EBV) infection. Here, we demonstrate that NPC displays frequent dysregulation of the Hedgehog (HH) pathway, a pathway implicated in the maintenance of stem cells, but whose aberrant activation in adult tissues can lead to cancer. Using authentic EBV-positive carcinoma-derived cell lines and nasopharyngeal epithelial cell lines latently infected with EBV as models for NPC in vitro, we show that EBV activates the HH signalling pathway through autocrine induction of SHH ligand. Moreover, we find that constitutive engagement of the HH pathway induces the expression of a number of stemness-associated genes and imposes stem-like characteristics on EBV-infected epithelial cells in vitro. Using epithelial cells expressing individual EBV latent genes detected in NPC, we show that EBNA1, LMP1, and LMP2A are all capable of inducing SHH ligand and activating the HH pathway, but only LMP1 and LMP2A are able to induce expression of stemness-associated marker genes. Our findings not only identify a role for dysregulated HH signalling in NPC oncogenesis, but also provide a novel rationale for therapeutic intervention.

Abstract PD3-5: Survival benefit conferred by the androgen receptor is lost in aromatase inhibitor treated breast cancer

Aromatase Inhibitors have proven to be most effective in the treatment of post-menopausal breast cancer. Their mode of action is to inhibit the synthesis of estrogen (estrone) by the aromatase enzyme Cyp 19 thereby blocking ligand-dependent activation of the estrogen receptor. What has not been addressed to date is how cells that are deprived of estrogen, may potentially, adapt to the more androgenic environment resulting from long-term treatment with AI therapy. Research from our lab has identified the homeobox protein, HOXC11, to be an indicator of poor response to endocrine therapy and development of metastasis. To further our understanding of HOXC11 and its role in the development of endocrine-resistance and metastatic spread we undertook an RNA-seq experiment to identify its target genes in resistant breast cancer. This analysis identified PSAP, IFIT1 and HSP90AA1. Both PSAP (an androgen agonist) and HSP90AA1 (AR chaperone) are closely associated with AR which led to further investigation into the role of HOXC11 in the development of steroidal adaptability in Letrozole-resistant breast cancer. We hypothesize that HOXC11 regulated expression of PSAP results in oncogenic activation of AR in an AI resistant setting. Our findings have shown that AI-resistant cell lines in vitro have significantly elevated levels of AR and that loss of HOXC11 results in concommitant decrease in AR mRNA. In AI resistance expression of HOXC11 results in upregulation/stabilization of AR by PSAP thus enabling the tumour to adapt to use androgenic steroids for cell proliferation. The anti-androgen, Bicalutamide, reduces cell proliferation and cell motility in AI resistant cell lines. Survival analysis of AR in a TMA (n = 488) indicates that AR confers a survival benefit in the tamoxifen treated population. This protective effect is diminished in patients receiving AI therapy and is reflected in the altered Hazard Ratio of AR from the total population (HR: 0.485) to the AI treated cohort (HR: 1.197). Secreted PSAP was readily detectable in breast cancer patient serum and associates significantly with expression of HOXC11 in matched patient tissue (∼20). PSAP is associated with poor response to endocrine therapy and metastatic spread of prostate cancer and as it is secreted it could potentially be used to monitor patients on AI who might benefit from dual targeted therapy treatment.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD3-5.

Inhibition of the LKB1-AMPK pathway by the Epstein-Barr virus-encoded LMP1 promotes proliferation and transformation of human nasopharyngeal epithelial cells

The association of Epstein-Barr virus (EBV) infection with the development of nasopharyngeal carcinoma (NPC) is well established. Latent membrane protein 1 (LMP1), the major oncogene encoded by EBV, is believed to play a crucial role in NPC pathogenesis by virtue of its ability to constitutively activate multiple cell signalling pathways. The LKB1-AMPK pathway is a master regulator of cellular metabolism that, via modulation of energy metabolism, has tumour suppressor activity. In this study we identify a novel ability of LMP1 to inhibit the LKB1-AMPK pathway through phosphorylation of LKB1 at serine 428 with subsequent suppression of the phosphorylation of AMPK and its substrates, ACC and Raptor. We show that MEK/ERK-MAPK signalling, activated by the CTAR1 domain of LMP1, is responsible for LKB1-AMPK inactivation. In addition, reactivation of AMPK signalling by AMPK activator, AICAR, abolished LMP1-induced cellular transformation (proliferation and anchorage-independent growth) in nasopharyngeal epithelial cells. Immunohistochemical staining revealed that a low level of phosphorylated AMPK is common in primary NPC specimens, and that this correlated significantly with the expression of LMP1. AICAR treatment inhibited the proliferation and anchorage-independent growth of NPC cells as well as potentiating the cytotoxic effect of the chemotherapeutic drug 5-fluorouracil. The current findings demonstrate that LMP1-mediated AMPK inactivation contributes to the proliferation and transformation of epithelial cells, thereby implicating the LKB1-AMPK pathway in the EBV-driven pathogenesis of NPC. Our findings also suggest that AMPK activators could be used to enhance the efficacy of conventional chemotherapeutic agents in the treatment of local and metastatic NPC.

A global view of the oncogenic landscape in nasopharyngeal carcinoma: an integrated analysis at the genetic and expression levels

Previous studies have reported that the tumour cells of nasopharyngeal carcinoma (NPC) exhibit recurrent chromosome abnormalities. These genetic changes are broadly assumed to lead to changes in gene expression which are important for the pathogenesis of this tumour. However, this assumption has yet to be formally tested at a global level. Therefore a genome wide analysis of chromosome copy number and gene expression was performed in tumour cells micro-dissected from the same NPC biopsies. Cellular tumour suppressor and tumour-promoting genes (TSG, TPG) and Epstein-Barr Virus (EBV)-encoded oncogenes were examined. The EBV-encoded genome maintenance protein EBNA1, along with the putative oncogenes LMP1, LMP2 and BARF1 were expressed in the majority of NPCs that were analysed. Significant downregulation of expression in an average of 76 cellular TSGs per tumour was found, whilst a per-tumour average of 88 significantly upregulated, TPGs occurred. The expression of around 60% of putative TPGs and TSGs was both up-and down-regulated in different types of cancer, suggesting that the simplistic classification of genes as TSGs or TPGs may not be entirely appropriate and that the concept of context-dependent onco-suppressors may be more extensive than previously recognised. No significant enrichment of TPGs within regions of frequent genomic gain was seen but TSGs were significantly enriched within regions of frequent genomic loss. It is suggested that loss of the FHIT gene may be a driver of NPC tumourigenesis. Notwithstanding the association of TSGs with regions of genomic loss, on a gene by gene basis and excepting homozygous deletions and high-level amplification, there is very little correlation between chromosomal copy number aberrations and expression levels of TSGs and TPGs in NPC.

Junctional adhesion molecule-A is co-expressed with HER2 in breast tumors and acts as a novel regulator of HER2 protein degradation and signaling

Junctional adhesion molecule-A (JAM-A) is a membranous cell-cell adhesion protein involved in tight-junction formation in epithelial and endothelial cells. Its overexpression in breast tumors has recently been linked with increased risk of metastasis. We sought to identify if JAM-A overexpression was associated with specific subtypes of breast cancer as defined by the expression of human epidermal growth factor receptor-2 (HER2), estrogen receptor (ER) and progesterone receptor. To this end, JAM-A immunohistochemistry was performed in two breast cancer tissue microarrays. In parallel, cross-talk between JAM-A, HER2 and ER was examined in several breast cell lines, using complementary genetic and pharmacological approaches. High JAM-A expression correlated significantly with HER2 protein expression, ER negativity, lower patient age, high-grade breast cancers, and aggressive luminal B, HER2 and basal subtypes of breast cancer. JAM-A and HER2 were co-expressed at high levels in vitro in SKBR3, UACC-812, UACC-893 and MCF7-HER2 cells. Knockdown or functional antagonism of HER2 did not alter JAM-A expression in any cell line tested. Interestingly, however, JAM-A knockdown decreased HER2 and ER-α expression, resulting in reduced levels of phospho-(active) AKT without an effect on the extracellular signal-related kinase phosphorylation. The downstream effects of JAM-A knockdown on HER2 and phospho-AKT were partially reversed upon treatment with the proteasomal inhibitor MG132. We conclude that JAM-A is co-expressed with HER2 and associates with aggressive breast cancer phenotypes. Furthermore, we speculate that JAM-A may regulate HER2 proteasomal degradation and activity, potentially offering a promise as a therapeutic target in HER2-positive breast cancers.

The role of the EBV-encoded latent membrane proteins LMP1 and LMP2 in the pathogenesis of nasopharyngeal carcinoma (NPC)

Although frequently expressed in EBV-positive malignancies, the contribution of the oncogenic latent membrane proteins, LMP1 and LMP2, to the pathogenesis of nasopharyngeal carcinoma (NPC) is not fully defined. As a key effector in EBV-driven B cell transformation and an established "transforming" gene, LMP1 displays oncogenic properties in rodent fibroblasts and induces profound morphological and phenotypic effects in epithelial cells. LMP1 functions as a viral mimic of the TNFR family member, CD40, engaging a number of signalling pathways that induce morphological and phenotypic alterations in epithelial cells. Although LMP2A plays an essential role in maintaining viral latency in EBV infected B cells, its role in epithelial cells is less clear. Unlike LMP1, LMP2A does not display "classical" transforming functions in rodent fibroblasts but its ability to engage a number of potentially oncogenic cell signalling pathways suggests that LMP2A can also participate in EBV-induced epithelial cell growth transformation. Here we review the effects of LMP1 and LMP2 on various aspects of epithelial cell behaviour highlighting key aspects that may contribute to the pathogenesis of NPC.

P5-12-01: Aromatase Inhibitor Specific Metastasis Is Driven by the Steroid Receptor Coactivator SRC-1

Aromatase Inhibitors are currently one of the most promising therapies of estrogen-receptor positive breast cancer in postmenopausal women. Even though many women initially respond to the treatment, approximately 30–40% will acquire resistance and relapse within 5 years. The mechanisms involved in the development of resistance to AIs however are poorly understood as long term follow up is only now becoming available. To investigate the mechanisms involved in AI-specific tumour recurrence, we generated a cell line resistant to the AI Letrozole (LetR) and examined a cohort of endocrine treated breast cancer patients (n=150). In patients treated with a first-line AI (n=89), we found that hormone receptor switching between the primary tumour and the resistant metastasis was a common feature of disease recurrence. More so, this switch accompanied the development of a phenotype displaying an increase in migratory capacity and loss of organisation. Both the resistant cell model and AI resistant tumour samples expressed high levels of the steroid receptor coactivator SRC-1. We also found that the interaction between SRC-1 and the transcription factor Ets2 was involved in the regulation of Myc and MMP9 expression and that SRC-1 was required for the aggressive AI resistant phenotype. Expression of SRC-1 in the primary and/or recurrent tumour associated with poor disease free survival (p=0.01, n=89) in the AI treated population. A significant coassociation between SRC-1 and Ets2 in the nucleus of the recurrent tissue compared with the matched primary tumour was also observed (p=0.0004, n=3). These data describe a novel signaling mechanism of AI-specific metastatic progression where SRC-1 utilizes Ets2 to promote de-differentiation and migration to drive disease progression.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-12-01.

P4-01-10: The Role of the Steroid Receptor Coactivator SRC1 and Its Functional Partner HOXC11 in the Development of Endocrine Resistant Breast Cancer

Background: The steroid receptor coactivator; SRC1, has been well described in the development of endocrine resistant breast cancer. SRC1 associates with clinically aggressive tumours and promotion of distant metastasis. It directly interacts with the developmental transcription factor, HOXC11 and together they are found to strongly predict poor disease-free survival in breast cancer patients (hazard ratios: 5.79; P &lt; 0.0001). In this study, we investigate the mechanism of SRC1 and HOXC11 action in tumour adaptability and subsequent resistance to endocrine therapy.

Materials and Methods: Cells which are resistant to tamoxifen (LY2s) have enhanced SRC1 and HOXC11 mRNA and protein expression in comparison to their endocrine sensitive parent cells (MCF-7s). ChIP-sequencing data for SRC1- and HOXC11- DNA interactions in conjunction with DNA microarray and RNA-sequencing data identified potential signalling targets at play in the LY2 model of endocrine resistance. Real-time analysis and flow cytometry confirmed these interactions at a transcriptional and protein level. These observations were further confirmed in primary breast cancer cultures using flow cytometry.

Results: SRC1 and HOXC11 interactions are driven in tamoxifen treated LY2 resistant cells. Combined SRC1 ChIP-sequencing and expression array data analysed in conjunction with HOXC11 ChIP-sequencing and RNA-sequencing data reveal that the SRC1/HOXC11 transcriptional process can orchestrate the loss of luminal cell markers such as ERα, CD24 and PTCH1 whilst concomitantly upregulating mediators of tumourigenicity such as CD44 and MSI2. Primary breast cancer cultures confirm the loss of CD24 in tamoxifen resistant patients. In these patients, loss of CD24 was accompanied by loss of steroid receptor expression (ERα and PR) and by a gain of the basal marker CD44.

Discussion: Here, we describe a new signalling pathway where SRC1 and HOXC11 regulate two distinct but complementary mechanisms to drive tumour adaptability. Silencing of luminal cell markers and a concomitant increase in a basal cell phenotype has the potential to alter the survival mechanism of breast cancer cells to evade targeted therapy.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-01-10.

Smoking initiation is followed by the early acquisition of epigenetic change in cervical epithelium: a longitudinal study

BACKGROUND

To prove a causal link between an epigenetic change and an environmental or behavioural risk factor for a given disease, it is first necessary to show that the onset of exposure precedes the first detection of that epigenetic change in subjects who are still free of disease.

METHODS

Towards this end, a cohort of women aged 15-19 years, recruited soon after they first had sexual intercourse, were used to provide sequential observations on the relationship between cigarette smoking and the detection in cervical cytological samples of methylated forms of CDKN2A (p16) using nested methylation-specific polymerase chain reaction.

RESULTS

Among women who remained cytologically normal and who tested negative for human papillomavirus DNA in cervical smears during follow-up, those who first started to smoke during follow-up had an increased risk of acquiring CDKN2A methylation compared with never-smokers (odds ratio=3.67; 95% confidence interval 1.09-12.33; P=0.04).

CONCLUSION

Smoking initiation is associated with the appearance of methylated forms of CDKN2A.

Phase I/II trial of a dendritic cell vaccine transfected with DNA encoding melan A and gp100 for patients with metastatic melanoma

This trial tested a dendritic cell (DC) therapeutic cancer vaccine in which antigen is loaded using a novel non-viral transfection method enabling the uptake of plasmid DNA condensed with a cationic peptide. Proof of principle required the demonstration of diverse T lymphocyte responses following vaccination, including multiple reactivities restricted through both major histocompatibility complex (MHC) class I and II. Patients with advanced melanoma were offered four cycles of vaccination with autologous DC expressing melan A and gp100. Disease response was measured using Response Evaluation Criteria in Solid Tumours. Circulating MHC class I- and II-restricted responses were measured against peptide and whole antigen targets using interferon-γ ELIspot and enzyme-linked immunosorbent assay assays, respectively. Responses were analyzed across the trial population and presented descriptively for some individuals. Twenty-five patients received at least one cycle. Vaccination was well tolerated. Three patients had reduction in disease volume. Across the trial population, vaccination resulted in an expansion of effector responses to both antigens, to the human leukocyte antigen A2-restricted modified epitope, melan A ELAGIGILTV, and to a panel of MHC class I- and II-restricted epitopes. Vaccination with mature DC non-virally transfected with DNA encoding antigen had biological effect causing tumour regression and inducing diverse T lymphocyte responses.

Epstein-Barr virus-encoded EBNA1 enhances RNA polymerase III-dependent EBER expression through induction of EBER-associated cellular transcription factors

BACKGROUND

Epstein-Barr Virus (EBV)-encoded RNAs (EBERs) are non-polyadenylated RNA molecules transcribed from the EBV genome by RNA polymerase III (pol III). EBERs are the most abundant viral latent gene products, although the precise mechanisms by which EBV is able to achieve such high levels of EBER expression are not fully understood. Previously EBV has been demonstrated to induce transcription factors associated with EBER expression, including pol III transcription factors and ATF-2. We have recently demonstrated that EBV-encoded nuclear antigen-1 (EBNA1) induces cellular transcription factors, and given these findings, we investigated the role of EBNA1 in induction of EBER-associated transcription factors.

RESULTS

Our data confirm that in epithelial cells EBNA1 can enhance cellular pol III transcription. Transient expression of EBNA1 in Ad/AH cells stably expressing the EBERs led to induction of both EBER1 and EBER2 and conversely, expression of a dominant negative EBNA1 led to reduced EBER expression in EBV-infected Ad/AH cells. EBNA1 can induce transcription factors used by EBER genes, including TFIIIC, ATF-2 and c-Myc. A variant chromatin precipitation procedure showed that EBNA1 is associated with the promoters of these genes but not with the promoters of pol III-transcribed genes, including the EBERs themselves. Using shRNA knock-down, we confirm the significance of both ATF-2 and c-Myc in EBER expression. Further, functional induction of a c-Myc fusion protein led to increased EBER expression, providing c-Myc binding sites upstream of EBER1 were intact. In vivo studies confirm elevated levels of the 102 kD subunit of TFIIIC in the tumour cells of EBV-positive nasopharyngeal carcinoma biopsies.

CONCLUSIONS

Our findings reveal that EBNA1 is able to enhance EBER expression through induction of cellular transcription factors and add to the repertoire of EBNA1's transcription-regulatory properties.

A short 5' flanking region containing conserved sequences is required for silkworm alanine tRNA gene activity

Using partially deleted genes, we have identified an upstream control signal required for transcription of a Bombyx mori (silkworm) tRNA(2) (Ala) gene. The 5' boundary of this essential region lies between 34 and 11 nucleotides preceding the transcription initiation site. Sequences in the 5' half of the tRNA(2) (Ala) coding region are also important. Both regions contain oligonucleotides that are conserved among several Bombyx genes transcribed by RNA polymerase III, suggesting that these sequences may have a general control function.

Expression of B7 (CD80) and CD40 antigens and the CD40 ligand in Hodgkin's disease is independent of latent Epstein-Barr virus infection

Aim-To examine the expression of CD40 and B7 (CD80) antigens and the CD40 ligand in Hodgkin's disease.Methods-Antigen and ligand expression was studied in 17 cases of Hodgkin's disease using immunohistochemistry. The study included 11 cases of Hodgkin's disease in which latent Epstein-Barr virus (EBV) infection could be demonstrated within tumour cells by in situ hybridisation for the EBV encoded early RNAs (EBERs).Results-In all cases, irrespective of EBV status, Reed-Sternberg cells and their variants (HRS cells) showed strong expression of both B7 and CD40 antigens. CD40 ligand expression was not shown in HRS cells but was confined to a subset of small lymphocytes some of which were seen to be in intimate contact with HRS cells.Paraffin wax sections from a further 60 cases of Hodgkin's disease were examined for CD40 and EBER expression alone. The CD40 antigen was identified in HRS cells in all of these cases irrespective of EBER expression.Conclusions-As CD40 and B7 expression are features of professional antigen presenting cells, these results provide further evidence that HRS cells may have antigen presenting properties and that this may contribute to the characteristic recruitment and activation of non-malignant lymphocytes which is a feature of Hodgkin's disease. The ability of HRS cells to activate T(h) cells may in turn contribute to their own survival through the induction of the gp39/CD40 pathway.

Upregulation of Id1 by Epstein-Barr virus-encoded LMP1 confers resistance to TGFbeta-mediated growth inhibition

Background

Epstein-Barr virus (EBV)-encoded LMP1 protein is commonly expressed in nasopharyngeal carcinoma (NPC). LMP1 is a prime candidate for driving tumourigenesis given its ability to activate multiple signalling pathways and to alter the expression and activity of variety of downstream targets. Resistance to TGFβ-mediated cytostasis is one of the growth transforming effects of LMP1. Of the downstream targets manipulated by LMP1, the induction of Id1 and inactivation of Foxo3a appear particularly relevant to LMP1-mediated effects. Id1, a HLH protein is implicated in cell transformation and plays a role in cell proliferation, whilst Foxo3a, a transcription factor controls cell integrity and homeostasis by regulating apoptosis. The mechanism(s) by which LMP1 induces these effects have not been fully characterised.

Results

In this study, we demonstrate that the ability of LMP1 to induce the phosphorylation and inactivation of Foxo3a is linked to the upregulation of Id1. Furthermore, we show that the induction of Id1 is essential for the transforming function of LMP1 as over-expression of Id1 increases cell proliferation, attenuates TGFβ-SMAD-mediated transcription and renders cells refractory to TGFβ-mediated cytostasis. Id1 silencing in LMP1-expressing epithelial cells abolishes the inhibitory effect of LMP1 on TGFβ-mediated cell growth arrest and reduces the ability of LMP1 to attenuate SMAD transcriptional activity. In response to TGFβ stimulation, LMP1 does not abolish SMAD phosphorylation but inhibits p21 protein expression. In addition, we found the induction of Id1 in LMP1-expressing cells upon stimulation by TGFβ. We provide evidence that LMP1 suppresses the transcriptional repressor ATF3, possibly leading to the TGFβ-induced Id1 upregulation.

Conclusion

The current data provide novel information regarding the mechanisms by which LMP1 suppresses TGFβ-induced cytostasis, highlighting the importance of Id1 in LMP1 mediated cell transformation