The in situ transcriptomic landscape of breast tumour-associated and normal adjacent endothelial cells

BACKGROUND AND AIMS

Triple Negative Breast Cancer (TNBC) is associated with increased angiogenesis, which is known to aid tumour growth and metastasis. Anti-angiogenic therapies that have been developed to target this feature have mostly generated disappointing clinical results. Further research into targeted approaches is limited by a lack of understanding of the in situ molecular profile of tumour-associated vasculature. In this study, we aimed to understand the differences in the molecular profiles of tumour endothelial cells vs normal-adjacent endothelial cells in TNBC tissues.

METHOD

We have applied unbiased whole transcriptome spatial profiling of in situ gene expressions of endothelial cells localized in full-face patient TNBC tissues (n = 4) and normal-adjacent regions of the same patient breast tissues.

RESULTS

Our comparative analysis revealed that 2412 genes were differentially expressed (padj < 0.05) between the tumour endothelial cells and normal-adjacent endothelial cells. Pathway enrichment showed the enrichment of gene sets related to cell-cell, cell-ECM adhesion, chromatin organization and remodeling, and protein-DNA complex subunit organization.

CONCLUSION

Overall, the results revealed unique molecular profiles and signalling pathways of tumour-associated vasculature, which is a critical step towards larger cohort studies investigating potential targets for TNBC prognosis and anti-angiogenic treatments.

Real-world prevalence of PD-L1 expression in non-small cell lung cancer: an Australia-wide multi-centre retrospective observational study

An investigator-initiated, Australia-wide multi-centre retrospective observational study was undertaken to investigate the real-world prevalence of programmed death ligand-1 (PD-L1) expression in non-small cell lung carcinoma (NSCLC). Multiple centres around Australia performing PD-L1 immunohistochemistry (IHC) were invited to participate. Histologically confirmed NSCLC of any stage with a PD-L1 IHC test performed for persons aged ≥18 years between 1 January 2018 and 1 January 2020, and eligible for review, were identified at each centre, followed by data extraction and de-identification, after which data were submitted to a central site for collation and analysis. In total data from 6690 eligible PD-L1 IHC tests from histologically (75%) or cytologically (24%) confirmed NSCLC of any stage were reviewed from persons with a median age of 70 years, 43% of which were female. The majority (81%) of tests were performed using the PD-L1 IHC SP263 antibody with the Ventana BenchMark Ultra platform and 19% were performed using Dako PD-L1 IHC 22C3 pharmDx assay. Reported PD-L1 tumour proportion score (TPS) was ≥50% for 30% of all tests, with 62% and 38% scoring PD-L1 ≥1% and <1%, respectively. Relative prevalence of clinicopathological features with PD-L1 scores dichotomised to <50% and ≥50%, or to <1% and ≥1%, were examined. Females scored ≥1% slightly more often than males (64% vs 61%, respectively, p=0.013). However, there was no difference between sexes or age groups (<70 or ≥70 years) where PD-L1 scored ≥50%. Specimens from patients with higher stage (III/IV) scored ≥1% or ≥50% marginally more often compared to specimens from patients with lower stage (I/II) (p≤0.002). Proportions of primary and metastatic specimens did not differ where PD-L1 TPS was ≥1%, however more metastatic samples scored TPS ≥50% than primary samples (metastatic vs primary; 34% vs 27%, p<0.001). Cytology and biopsy specimens were equally reported, at 63% of specimens, to score TPS ≥1%, whereas cytology samples scored TPS ≥50% slightly more often than biopsy samples (34% vs 30%, respectively, p=0.004). Resection specimens (16% of samples tested) were reported to score TPS ≥50% or ≥1% less often than either biopsy or cytology samples (p<0.001). There was no difference in the proportion of tests with TPS ≥1% between PD-L1 IHC assays used, however the proportion of tests scored at TPS ≥50% was marginally higher for 22C3 compared to SP263 (34% vs 29%, respectively, p<0.001). These real-world Australian data are comparable to some previously published global real-world data, with some differences noted.

Abstract P4-07-26: Development of CDCP1-targeting antibody-drug conjugate for Triple negative and metastatic breast cancer

Introduction: CUB-domain containing- protein 1 (CDCP1) is a transmembrane receptor involved in the progression of several cancers. Recent studies demonstrate that CDCP1 is a rational target for the development of innovative targeted therapies for cancer including theranostics agents and antibody-drug conjugates. Objective/Methods: To determine the therapeutic potential of CDCP1 in breast cancer, we investigated its expression in multiple cohorts of breast cancer tissues by immunohistochemistry, as well as in various preclinical models including cell lines, primary cells and patient-derived xenografts using flow cytometry, western blot and immunofluorescence staining. Then, we evaluated the capacity of the CDCP1-targeting chimeric antibody ch10D7 to specifically accumulate in breast cancer lesions in in vivo preclinical models including patient-derived xenografts and breast cancer metastasis models. Finally, we determined the efficacy of the ch10D7-MMAE antibody-drug conjugate to kill breast cancer cells in vitro and breast tumours ex-vivo and in vivo. Results: The CDCP1 receptor is expressed at targetable level in a significant proportion of breast cancer cases with high/intermediate expression detected in ~30% of localized ER-positive cases, ~50% of metastatic ER-positive cases and &gt;70% of Triple negative or HER2-positive cases. Similar proportion of expression was detected in cellular models. We demonstrated that ch10D7 antibody labelled with the radionucleotide Zircodium-89 specifically accumulates in breast cancer lesions in vivo allowing the detection of mammary-fat pad implanted patient-derived xenografts and of breast cancer metastasis by PET/CT imaging. Finally, we confirmed that the ch10D7-MMAE antibody-drug conjugate is very efficient at inducing cell death in vitro as well as controlling primary tumour and metastatic tumour burden in pre-clinical models, conferring a significant survival advantage compared to classical therapy. Conclusion: Our work demonstrates that CDCP1 is a potential target to detect and limit the progression of breast tumours and that biomolecules specifically recognising this receptor are promising agents which could improve survival of patients.

Citation Format: Madeline Gough, Tashbib Khan, Kayden Kwah, Yaowu He, Gishan Ratnayake, Christopher Pyke, Cameron Snell, John Hooper, Thomas Kryza. Development of CDCP1-targeting antibody-drug conjugate for Triple negative and metastatic breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-26.

Exploring the Potential of PEG-Heparin Hydrogels to Support Long-Term Ex Vivo Culture of Patient-Derived Breast Explant Tissues

Breast cancer is a complex, highly heterogenous, and dynamic disease and the leading cause of cancer-related death in women worldwide. Evaluation of the heterogeneity of breast cancer and its various subtypes is crucial to identify novel treatment strategies that can overcome the limitations of currently available options. Explant cultures of human mammary tissue have been known to provide important insights for the study of breast cancer structure and phenotype as they include the context of the surrounding microenvironment, allowing for the comprehensive exploration of patient heterogeneity. However, the major limitation of currently available techniques remains the short-term viability of the tissue owing to loss of structural integrity. Here, an ex vivo culture model using star-shaped poly(ethylene glycol) and maleimide-functionalized heparin (PEG-HM) hydrogels to provide structural support to the explant cultures is presented. The mechanical support allows the culture of the human mammary tissue for up to 3 weeks and prevent disintegration of the cellular structures including the epithelium and surrounding stromal tissue. Further, maintenance of epithelial phenotype and hormonal receptors is observed for up to 2 weeks of culture which makes them relevant for testing therapeutic interventions. Through this study, the importance of donor-to-donor variability and intra-patient tissue heterogeneity is reiterated.

Abstract A17: The immune checkpoints TIGIT and PD-1 are markedly upregulated in NLPHL compared to classical Hodgkin Lymphoma

Hodgkin lymphoma (HL) comprises two distinct disease entities based on clinical, morphologic and genotypic characteristics. Relative to classical Hodgkin Lymphoma (cHL), nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is rare, and its tumor microenvironment (TME) is very poorly characterized. With the exception of rituximab, there are no targeted treatments nor advances in the treatment of NLPHL for decades. Unlike cHL, the utility of immune-checkpoint blockade (ICB) has not been evaluated in NLPHL. Diagnostic samples were collected from 49 NLPHL patients from 4 Australian centres and compared with stage-matched cHL patients (and with normal lymph nodes). An integrative transcriptomic, proteomic, T-cell clonal and functional analysis was performed to enable a comparison of the composition of the TME and its contribution to immune-evasion in NLPHL with cHL. 730 cancer-immune related genes were digitally quantified. Relative to cHL, gene set enrichment analysis identified T-cell receptor (TCR) and immune-checkpoint signaling pathway dysregulation in NLPHL. Most striking was prominent differential expression of the immune-transcriptome, particularly enrichment for programmed cell death-1 (PD-1) and T-cell Ig and ITIM domain (TIGIT) in NLPHL versus cHL. These were also over expressed compared to normal lymph nodes. Consistent with this, there was also upregulation of numerous T-cell markers (CD247, CD3D, GZMK, CD28, EOMES) in NLPHL. In contrast, immunosuppressive macrophage (CD163, CD36, CD68, COLEC12, MARCO) and regulatory T-cell genes (FOXP3) were higher in cHL. Importantly, PD-L1 and CD155 (respective ligands for PD-1 and TIGIT) were expressed at the surface of NLPHL and cHL malignant B-cells. Multispectral immunofluorescent microscopy showed intratumoral TIGIT+CD4+ and PD-1+CD4+ T-cells were markedly increased in NLPHL versus cHL and localised within NLPHL follicles. Expanded populations of intratumoral CD4+ T-cell clones were predominantly PD-1+ and frequently also TIGIT+. Multi-parameter flow cytometry and dimensionality reduction was used to establish the distribution of immune checkpoints within circulating T-cell subsets. PD-1+TIGIT+CD4+ T-cells were raised in circulating Treg, TH1 and TH2 subsets in NLPHL versus cHL, and PD-1+TIGIT+ TH2 T-cells displayed raised levels of the exhaustion marker EOMES, collectively indicating systemic T-cell dysfunction. To functionally demonstrate the utility of ICB to stimulate T-cells, an assay using cHL and/or NLPHL cell-lines co-cultured with a genetically engineered effector T-cell-line was developed. This showed that TIGIT/PD-1 dual-blockade was more effective than mono-blockade in inducing NLPHL and cHL tumor-directed CD4+ T-cell activation. Overall, our results indicate that immune-evasion mechanisms in NLPHL are distinct to those operative in cHL, with markedly greater T-cell, PD-1 and TIGIT dysregulation. PD-1 and/or TIGIT blockade warrants evaluation in NLPHL.

Citation Format: Jay Gunawardana, Soi C. Law, Muhammed B. Sabdia, Karolina Bednarska, Sandra Brosda, Andreea Zaharia, Hennes Tsang, Lilia M. de Long, Melinda Burgess, Dipti Talaulikar, Justina N. Lee, Emily Jude, Eliza A. Hawkes, Sanjiv Jain, Karthik Nath, Clare Gould, Fiona Swain, Joshua W. D. Tobin, Colm Keane, Simone Birch, Mohamed Shanavas, Cameron Snell, Maher K. Gandhi. The immune checkpoints TIGIT and PD-1 are markedly upregulated in NLPHL compared to classical Hodgkin Lymphoma [abstract]. In: Proceedings of the Third AACR International Meeting: Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2022 Jun 23-26; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2022;3(5_Suppl):Abstract nr A17.

Characterising 18F-fluciclovine uptake in breast cancer through the use of dynamic PET/CT imaging

BACKGROUND

18F-fluciclovine is a synthetic amino acid positron emission tomography (PET) radiotracer that is approved for use in prostate cancer. In this clinical study, we characterised the kinetic model best describing the uptake of 18F-fluciclovine in breast cancer and assessed differences in tracer kinetics and static parameters for different breast cancer receptor subtypes and tumour grades.

METHODS

Thirty-nine patients with pathologically proven breast cancer underwent 20-min dynamic PET/computed tomography imaging following the administration of 18F-fluciclovine. Uptake into primary breast tumours was evaluated using one- and two-tissue reversible compartmental kinetic models and static parameters.

RESULTS

A reversible one-tissue compartment model was shown to best describe tracer uptake in breast cancer. No significant differences were seen in kinetic or static parameters for different tumour receptor subtypes or grades. Kinetic and static parameters showed a good correlation.

CONCLUSIONS

18F-fluciclovine has potential in the imaging of primary breast cancer, but kinetic analysis may not have additional value over static measures of tracer uptake.

CLINICAL TRIAL REGISTRATION

NCT03036943.

ADGRL4/ELTD1 Expression in Breast Cancer Cells Induces Vascular Normalization and Immune Suppression

ELTD1/ADGRL4 expression is increased in the vasculature of a number of tumor types and this correlates with a good prognosis. Expression has also been reported in some tumor cells with high expression correlating with a good prognosis in hepatocellular carcinoma (HCC) and a poor prognosis in glioblastoma. Here we show that 35% of primary human breast tumors stain positively for ELTD1, with 9% having high expression that correlates with improved relapse-free survival. Using immunocompetent, syngeneic mouse breast cancer models we found that tumors expressing recombinant murine Eltd1 grew faster than controls, with an enhanced ability to metastasize and promote systemic immune effects. The Eltd1-expressing tumors had larger and better perfused vessels and tumor-endothelial cell interaction led to the release of proangiogenic and immune-modulating factors. M2-like macrophages increased in the stroma along with expression of programmed death-ligand 1 (PD-L1) on tumor and immune cells, to create an immunosuppressive microenvironment that allowed Eltd1-regulated tumor growth in the presence of an NY-ESO-1-specific immune response. Eltd1-positive tumors also responded better to chemotherapy which could explain the relationship to a good prognosis observed in primary human cases. Thus, ELTD1 expression may enhance delivery of therapeutic antibodies to reverse the immunosuppression and increase response to chemotherapy and radiotherapy in this subset of tumors. ELTD1 may be useful as a selection marker for such therapies. IMPLICATIONS: ELTD1 expression in mouse breast tumors creates an immunosuppressive microenvironment and increases vessel size and perfusion. Its expression may enhance the delivery of therapies targeting the immune system.

Targeting Replication Stress Using CHK1 Inhibitor Promotes Innate and NKT Cell Immune Responses and Tumour Regression

Drugs selectively targeting replication stress have demonstrated significant preclinical activity, but this has not yet translated into an effective clinical treatment. Here we report that targeting increased replication stress with a combination of Checkpoint kinase 1 inhibitor (CHK1i) with a subclinical dose of hydroxyurea targets also promotes pro-inflammatory cytokine/chemokine expression that is independent of cGAS-STING pathway activation and immunogenic cell death in human and murine melanoma cells. In vivo, this drug combination induces tumour regression which is dependent on an adaptive immune response. It increases cytotoxic CD8+ T cell activity, but the major adaptive immune response is a pronounced NKT cell tumour infiltration. Treatment also promotes an immunosuppressive tumour microenvironment through CD4+ Treg and FoxP3+ NKT cells. The number of these accumulated during treatment, the increase in FoxP3+ NKT cells numbers correlates with the decrease in activated NKT cells, suggesting they are a consequence of the conversion of effector to suppressive NKT cells. Whereas tumour infiltrating CD8+ T cell PD-1 and tumour PD-L1 expression was increased with treatment, peripheral CD4+ and CD8+ T cells retained strong anti-tumour activity. Despite increased CD8+ T cell PD-1, combination with anti-PD-1 did not improve response, indicating that immunosuppression from Tregs and FoxP3+ NKT cells are major contributors to the immunosuppressive tumour microenvironment. This demonstrates that therapies targeting replication stress can be well tolerated, not adversely affect immune responses, and trigger an effective anti-tumour immune response.

Abstract PO033: FGFR2 isoform switching strongly associates with progestin treatment failure in atypical hyperplasia and well-differentiated endometrial cancer

Introduction: Women with atypical hyperplasia (AH) or well-differentiated endometrioid endometrial carcinoma (EEC) who wish to retain fertility and/or with severe comorbidities that preclude surgery, are treated with progestin. Previously, we reported FGFR2c was associated with aggressive tumour behaviour and poor survival outcome in EEC. The purpose of this study was to estimate the response rate of Levonorgestrel IUD treatment and determine the association of FGFR2b and FGFR2c expression with outcome in women with AH/borderline histology (BL) and EEC treated with progestin.

Method: BaseScope RNA ISH and immunohistochemistry assays were deployed to detect (FGFR2b and FGFR2c mRNA) and (FGFR2 protein and progesterone receptors), respectively in 89 diagnostic biopsies of patients with AH/BL and EEC treated with progestin. Kaplan Meier Curve and Cox regression model analyses were performed to evaluate the predictive value of FGFR2b and FGFR2c in this cohort.

Results: The complete resolution rate (CRR) and overall response rate (ORR) at any time point in the whole cohort were 26/82 (32%) and 35/82 (43%), respectively. When stratified by histologic diagnosis CRR was 47.5% and 17% and ORR 63% and 24% for AH/BL and EEC, respectively. The recurrence rate was 28.7%. FGFR2c expression was documented in 12/72 (15%) cases. Both univariable and multivariable Cox regression analyses showed women with FGFR2c expression were 5-fold more likely to progress compared with FGFR2b positive women (HR 5.4, P&lt;0.0001) and (HR, 5, P&lt;0.001), respectively.

Conclusion: Progestin treatment is less effective in patients with EEC. Notably, FGFR2c expression appears to be strongly associated with progestin treatment failure.

Citation Format: Asmerom Sengal, Deborah Smith, Rebecca Rogers, Cameron Snell, Elizabeth Williams, Pamela Pollock. FGFR2 isoform switching strongly associates with progestin treatment failure in atypical hyperplasia and well-differentiated endometrial cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference: Endometrial Cancer: New Biology Driving Research and Treatment; 2020 Nov 9-10. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(3_Suppl):Abstract nr PO033.

Combined use of subclinical hydroxyurea and CHK1 inhibitor effectively controls melanoma and lung cancer progression, with reduced normal tissue toxicity compared to gemcitabine

Drugs such as gemcitabine that increase replication stress are effective chemotherapeutics in a range of cancer settings. These drugs effectively block replication and promote DNA damage, triggering a cell cycle checkpoint response through the ATR–CHK1 pathway. Inhibiting this signalling pathway sensitises cells to killing by replication stress‐inducing drugs. Here, we investigated the effect of low‐level replication stress induced by low concentrations (> 0.2 mm) of the reversible ribonucleotide reductase inhibitor hydroxyurea (HU), which slows S‐phase progression but has little effect on cell viability or proliferation. We demonstrate that HU effectively synergises with CHK1, but not ATR inhibition, in > 70% of melanoma and non‐small‐cell lung cancer cells assessed, resulting in apoptosis and complete loss of proliferative potential in vitro and in vivo. Normal fibroblasts and haemopoietic cells retain viability and proliferative potential following exposure to CHK1 inhibitor plus low doses of HU, but normal cells exposed to CHK1 inhibitor combined with submicromolar concentrations of gemcitabine exhibited complete loss of proliferative potential. The effects of gemcitabine on normal tissue correlate with irreversible ATR–CHK1 pathway activation, whereas low doses of HU reversibly activate CHK1 independently of ATR. The combined use of CHK1 inhibitor and subclinical HU also triggered an inflammatory response involving the recruitment of macrophages in vivo. These data indicate that combining CHK1 inhibitor with subclinical HU is superior to combination with gemcitabine, as it provides equal anticancer efficacy but with reduced normal tissue toxicity. These data suggest a significant proportion of melanoma and lung cancer patients could benefit from treatment with this drug combination.

Visual loss in pregnancy

Visual loss in pregnancy may be caused by a variety of reasons including pituitary adenomas. Prolactinomas (PRLs) are the most common hormone-secreting tumours in pregnant women. As most PRLs present with menstrual abnormalities, infertility or galactorrhoea, they are most commonly diagnosed before pregnancy. We present the case of a 30-year-old primigravida who presented at 36⁺⁵ weeks gestation with headaches and left-sided visual loss. MRI of the pituitary gland confirmed a 10×11 mm left suprasellar mass. Results of her anterior pituitary function were unremarkable for her gestational age. Postpartum, she underwent an endoscopic endonasal resection of the pituitary tumour. The histology was consistent with a PRL. Literature review reveals only one possible case of a new diagnosis of a PRL during pregnancy. It highlights the importance to consider a wide range of differential diagnoses when assessing visual loss in pregnancy.

Integrated Pharmacodynamic Analysis Identifies Two Metabolic Adaption Pathways to Metformin in Breast Cancer

Late-phase clinical trials investigating metformin as a cancer therapy are underway. However, there remains controversy as to the mode of action of metformin in tumors at clinical doses. We conducted a clinical study integrating measurement of markers of systemic metabolism, dynamic FDG-PET-CT, transcriptomics, and metabolomics at paired time points to profile the bioactivity of metformin in primary breast cancer. We show metformin reduces the levels of mitochondrial metabolites, activates multiple mitochondrial metabolic pathways, and increases 18-FDG flux in tumors. Two tumor groups are identified with distinct metabolic responses, an OXPHOS transcriptional response (OTR) group for which there is an increase in OXPHOS gene transcription and an FDG response group with increased 18-FDG uptake. Increase in proliferation, as measured by a validated proliferation signature, suggested that patients in the OTR group were resistant to metformin treatment. We conclude that mitochondrial response to metformin in primary breast cancer may define anti-tumor effect.

Expression of CDCA3 Is a Prognostic Biomarker and Potential Therapeutic Target in Non-Small Cell Lung Cancer

INTRODUCTION

NSCLC is the leading cause for cancer-related deaths worldwide. New therapeutic targets are needed, as development of resistance to current treatment, such as platinum-based chemotherapy, is inevitable. The purpose of this study was to determine the functional relevance and therapeutic potential of cell division cycle associated 3 protein (CDCA3) in NSCLC.

METHODS

The expression of CDCA3 in squamous and nonsquamous NSCLC was investigated by using bioinformatics, Western blot analysis of matched tumor and normal tissue, and immunohistochemistry of a tissue microarray. The function of CDCA3 in NSCLC was determined by using several in vitro assays with small interfering RNA depleting CDCA3 in a panel of three immortalized human bronchial epithelial cell (HBEC) lines and seven NSCLC cell lines.

RESULTS

In this study, cell division cycle associated 3 gene (CDCA3) transcripts were identified as highly increased in NSCLC versus in nonmalignant tissue, with high levels of CDCA3 being associated with poor patient prognosis. CDCA3 protein was also increased in NSCLC tissue and expression was limited to tumor cells. CDCA3 expression was similarly increased in a panel of NSCLC cell lines compared with in three HBEC lines. Although depletion of CDCA3 in the HBEC lines did not affect cellular proliferation, depletion of CDCA3 expression markedly reduced the proliferation of all NSCLC cell lines. CDCA3 depletion caused a defective G2/M-phase cell cycle progression, upregulation of p21 independent of p53, and induction of cellular senescence.

CONCLUSIONS

Our findings highlight CDCA3 as a prognostic factor and potential novel therapeutic target in NSCLC through inhibition of tumor growth and promotion of tumor senescence.

Disrupting Hypoxia-Induced Bicarbonate Transport Acidifies Tumor Cells and Suppresses Tumor Growth

Tumor hypoxia is associated clinically with therapeutic resistance and poor patient outcomes. One feature of tumor hypoxia is activated expression of carbonic anhydrase IX (CA9), a regulator of pH and tumor growth. In this study, we investigated the hypothesis that impeding the reuptake of bicarbonate produced extracellularly by CA9 could exacerbate the intracellular acidity produced by hypoxic conditions, perhaps compromising cell growth and viability as a result. In 8 of 10 cancer cell lines, we found that hypoxia induced the expression of at least one bicarbonate transporter. The most robust and frequent inductions were of the sodium-driven bicarbonate transporters SLC4A4 and SLC4A9, which rely upon both HIF1α and HIF2α activity for their expression. In cancer cell spheroids, SLC4A4 or SLC4A9 disruption by either genetic or pharmaceutical approaches acidified intracellular pH and reduced cell growth. Furthermore, treatment of spheroids with S0859, a small-molecule inhibitor of sodium-driven bicarbonate transporters, increased apoptosis in the cell lines tested. Finally, RNAi-mediated attenuation of SLC4A9 increased apoptosis in MDA-MB-231 breast cancer spheroids and dramatically reduced growth of MDA-MB-231 breast tumors or U87 gliomas in murine xenografts. Our findings suggest that disrupting pH homeostasis by blocking bicarbonate import might broadly relieve the common resistance of hypoxic tumors to anticancer therapy. Cancer Res; 76(13); 3744-55. ©2016 AACR.

PAT4 levels control amino-acid sensitivity of rapamycin-resistant mTORC1 from the Golgi and affect clinical outcome in colorectal cancer

Tumour cells can use strategies that make them resistant to nutrient deprivation to outcompete their neighbours. A key integrator of the cell's responses to starvation and other stresses is amino-acid-dependent mechanistic target of rapamycin complex 1 (mTORC1). Activation of mTORC1 on late endosomes and lysosomes is facilitated by amino-acid transporters within the solute-linked carrier 36 (SLC36) and SLC38 families. Here, we analyse the functions of SLC36 family member, SLC36A4, otherwise known as proton-assisted amino-acid transporter 4 (PAT4), in colorectal cancer. We show that independent of other major pathological factors, high PAT4 expression is associated with reduced relapse-free survival after colorectal cancer surgery. Consistent with this, PAT4 promotes HCT116 human colorectal cancer cell proliferation in culture and tumour growth in xenograft models. Inducible knockdown in HCT116 cells reveals that PAT4 regulates a form of mTORC1 with two distinct properties: first, it preferentially targets eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), and second, it is resistant to rapamycin treatment. Furthermore, in HCT116 cells two non-essential amino acids, glutamine and serine, which are often rapidly metabolised by tumour cells, regulate rapamycin-resistant mTORC1 in a PAT4-dependent manner. Overexpressed PAT4 is also able to promote rapamycin resistance in human embryonic kidney-293 cells. PAT4 is predominantly associated with the Golgi apparatus in a range of cell types, and in situ proximity ligation analysis shows that PAT4 interacts with both mTORC1 and its regulator Rab1A on the Golgi. These findings, together with other studies, suggest that differentially localised intracellular amino-acid transporters contribute to the activation of alternate forms of mTORC1. Furthermore, our data predict that colorectal cancer cells with high PAT4 expression will be more resistant to depletion of serine and glutamine, allowing them to survive and outgrow neighbouring normal and tumorigenic cells, and potentially providing a new route for pharmacological intervention.

Why some tumours trigger neovascularisation and others don't: the story thus far

BACKGROUND

Angiogenesis is not essential for tumours to develop and expand, as cancer can also grow in a non-angiogenic fashion, but why this type of growth occurs is unknown. Surprisingly, our data from mRNA transcription profiling did not show any differences in the classical angiogenic pathways, but differences were observed in mitochondrial metabolic pathways, suggesting a key role for metabolic reprogramming. We then validated these results with mRNA profiling by investigating differential protein expression via immunohistochemistry in angiogenic and non-angiogenic non-small cell lung cancers (NSCLCs).

METHODS

Immunohistochemical staining for 35 angiogenesis- and hypoxia-related biomarkers were performed on a collection of 194 angiogenic and 73 non-angiogenic NSCLCs arranged on tissue microarrays. Sequencing of P53 was performed with frozen tissue samples of NSCLC.

RESULTS

The non-angiogenic tumours were distinguished from the angiogenic ones by having higher levels of proteins associated with ephrin pathways, mitochondria, cell biogenesis, and hypoxia-inducible factor 1 (HIF1) regulation by oxygen and transcription of HIF-controlled genes but lower levels of proteins involved in the stroma, cell-cell signaling and adhesion, integrins, and Delta-Notch and epidermal growth factor (EGF)-related signaling. However, proteins classically associated with angiogenesis were present in both types of tumours at very comparable levels. Cytoplasmic expression of P53 was strongly associated with non-angiogenic tumours. A pilot investigation showed that P53 mutations were observed in 32.0% of angiogenic cases but in 71.4% of non-angiogenic tumours.

CONCLUSIONS

Our observations thus far indicate that both angiogenic and non-angiogenic tumours experience hypoxia/HIF and vascular endothelial growth factor (VEGF) pathway protein expression in a comparable fashion. However, angiogenesis does not ensue in the non-angiogenic tumours. Surprisingly, metabolic reprogramming seems to distinguish these two types of neoplastic growth. On the basis of these results, we raise the hypothesis that in some, but not in all cases, initial tissue remodeling and/or inflammation could be one of the secondary steps necessary to trigger angiogenesis. In the non-angiogenic tumours, in which neovascularisation fails to occur, HIF pathway activation could be the driving force toward metabolic reprogramming.

A core human primary tumor angiogenesis signature identifies the endothelial orphan receptor ELTD1 as a key regulator of angiogenesis

Limited clinical benefits derived from anti-VEGF therapy have driven the identification of new targets involved in tumor angiogenesis. Here, we report an integrative meta-analysis to define the transcriptional program underlying angiogenesis in human cancer. This approach identified ELTD1, an orphan G-protein-coupled receptor whose expression is induced by VEGF/bFGF and repressed by DLL4 signaling. Extensive analysis of multiple cancer types demonstrates significant upregulation of ELTD1 in tumor-associated endothelial cells, with a higher expression correlating with favorable prognosis. Importantly, ELTD1 silencing impairs endothelial sprouting and vessel formation in vitro and in vivo, drastically reducing tumor growth and greatly improving survival. Collectively, these results provide insight into the regulation of tumor angiogenesis and highlight ELTD1 as key player in blood vessel formation.

Reciprocal expression of the endocytic protein HIP1R and its repressor FOXP1 predicts outcome in R-CHOP-treated diffuse large B-cell lymphoma patients

We previously identified autoantibodies to the endocytic-associated protein Huntingtin-interacting protein 1-related (HIP1R) in diffuse large B-cell lymphoma (DLBCL) patients. HIP1R regulates internalization of cell surface receptors via endocytosis, a process relevant to many therapeutic strategies including CD20 targeting with rituximab. In this study, we characterized HIP1R expression patterns, investigated a mechanism of transcriptional regulation and its clinical relevance in DLBCL patients treated with immunochemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone, R-CHOP). HIP1R was preferentially expressed in germinal center B-cell-like DLBCL (P<0.0001) and inversely correlated with the activated B-cell-like DLBCL (ABC-DLBCL) associated transcription factor, Forkhead box P1 (FOXP1). HIP1R was confirmed as a direct FOXP1 target gene in ABC-DLBCL by FOXP1-targeted silencing and chromatin immunoprecipitation. Lower HIP1R protein expression (≤ 10% tumoral positivity) significantly correlated with inferior overall survival (OS, P=0.0003) and progression-free survival (PFS, P=0.0148) in R-CHOP-treated DLBCL patients (n=157). Reciprocal expression with ≥ 70% FOXP1 positivity defined FOXP1(hi)/HIP1R(lo) patients with particularly poor outcome (OS, P=0.0001; PFS, P=0.0016). In an independent R-CHOP-treated DLBCL (n=233) microarray data set, patients with transcript expression in lower quartile HIP1R and FOXP1(hi)/HIP1R(lo) subgroups exhibited worse OS, P=0.0044 and P=0.0004, respectively. HIP1R repression by FOXP1 is strongly associated with poor outcome, thus further understanding of FOXP1-HIP1R and/or endocytic signaling pathways might give rise to novel therapeutic options for DLBCL.

Vessel co-option in primary human tumors and metastases: an obstacle to effective anti-angiogenic treatment?

Angiogenesis has been regarded as essential for tumor growth and progression. Studies of many human tumors, however, suggest that their microcirculation may be provided by nonsprouting vessels and that a variety of tumors can grow and metastasize without angiogenesis. Vessel co-option, where tumor cells migrate along the preexisting vessels of the host organ, is regarded as an alternative tumor blood supply. Vessel co-option may occur in many malignancies, but so far mostly reported in highly vascularized tissues such as brain, lung, and liver. In primary and metastatic lung cancer and liver metastasis from different primary origins, as much as 10–30% of the tumors are reported to use this alternative blood supply. In addition, vessel co-option is introduced as a potential explanation of antiangiogenic drug resistance, although the impact of vessel co-option in this clinical setting is still to be further explored. In this review we discuss tumor vessel co-option with specific examples of vessel co-option in primary and secondary tumors and a consideration of the clinical implications of this alternative tumor blood supply.

Both primary and metastatic tumors use preexisting host tissue vessels as their blood supply. Tumors may grow to a clinically detectable size without angiogenesis and makes them less likely to respond to drugs designed to target the abnormal vasculature produced by angiogenesis, but further studies to explore the biological and clinical implication of these co-opted vessels is needed.

Glucose utilization via glycogen phosphorylase sustains proliferation and prevents premature senescence in cancer cells

Metabolic reprogramming of cancer cells provides energy and multiple intermediates critical for cell growth. Hypoxia in tumors represents a hostile environment that can encourage these transformations. We report that glycogen metabolism is upregulated in tumors in vivo and in cancer cells in vitro in response to hypoxia. In vitro, hypoxia induced an early accumulation of glycogen, followed by a gradual decline. Concordantly, glycogen synthase (GYS1) showed a rapid induction, followed by a later increase of glycogen phosphorylase (PYGL). PYGL depletion and the consequent glycogen accumulation led to increased reactive oxygen species (ROS) levels that contributed to a p53-dependent induction of senescence and markedly impaired tumorigenesis in vivo. Metabolic analyses indicated that glycogen degradation by PYGL is important for the optimal function of the pentose phosphate pathway. Thus, glycogen metabolism is a key pathway induced by hypoxia, necessary for optimal glucose utilization, which represents a targetable mechanism of metabolic adaptation.

Carbonic anhydrase IX promotes tumor growth and necrosis in vivo and inhibition enhances anti-VEGF therapy

PURPOSE

Bevacizumab, an anti-VEGFA antibody, inhibits the developing vasculature of tumors, but resistance is common. Antiangiogenic therapy induces hypoxia and we observed increased expression of hypoxia-regulated genes, including carbonic anhydrase IX (CAIX), in response to bevacizumab treatment in xenografts. CAIX expression correlates with poor prognosis in most tumor types and with worse outcome in bevacizumab-treated patients with metastatic colorectal cancer, malignant astrocytoma, and recurrent malignant glioma.

EXPERIMENTAL DESIGN

We knocked down CAIX expression by short hairpin RNA in a colon cancer (HT29) and a glioblastoma (U87) cell line which have high hypoxic induction of CAIX and overexpressed CAIX in HCT116 cells which has low CAIX. We investigated the effect on growth rate in three-dimensional (3D) culture and in vivo, and examined the effect of CAIX knockdown in combination with bevacizumab.

RESULTS

CAIX expression was associated with increased growth rate in spheroids and in vivo. Surprisingly, CAIX expression was associated with increased necrosis and apoptosis in vivo and in vitro. We found that acidity inhibits CAIX activity over the pH range found in tumors (pK = 6.84), and this may be the mechanism whereby excess acid self-limits the build-up of extracellular acid. Expression of another hypoxia inducible CA isoform, CAXII, was upregulated in 3D but not two-dimensional culture in response to CAIX knockdown. CAIX knockdown enhanced the effect of bevacizumab treatment, reducing tumor growth rate in vivo.

CONCLUSION

This work provides evidence that inhibition of the hypoxic adaptation to antiangiogenic therapy enhances bevacizumab treatment and highlights the value of developing small molecules or antibodies which inhibit CAIX for combination therapy.

DLL4-Notch signaling mediates tumor resistance to anti-VEGF therapy in vivo

Resistance to VEGF inhibitors is emerging as a major clinical problem. Notch signaling has been implicated in tumor angiogenesis. Therefore, to investigate mechanisms of resistance to angiogenesis inhibitors, we transduced human glioblastoma cells with retroviruses encoding Notch delta-like ligand 4 (DLL4), grew them as tumor xenografts and then treated the murine hosts with the VEGF-A inhibitor bevacizumab. We found that DLL4-mediated tumor resistance to bevacizumab in vivo. The large vessels induced by DLL4-Notch signaling increased tumor blood supply and were insensitive to bevacizumab. However, blockade of Notch signaling by dibenzazepine, a γ-secretase inhibitor, disrupted the large vessels and abolished the tumor resistance. Multiple molecular mechanisms of resistance were shown, including decreased levels of hypoxia-induced VEGF and increased levels of the VEGF receptor VEGFR1 in the tumor stroma, decreased levels of VEGFR2 in large blood vessels, and reduced levels of VEGFR3 overall. DLL4-expressing tumors were also resistant to a VEGFR targeting multikinase inhibitor. We also observed activation of other pathways of tumor resistance driven by DLL4-Notch signaling, including the FGF2-FGFR and EphB4-EprinB2 pathways, the inhibition of which reversed tumor resistance partially. Taken together, our findings show the importance of classifying mechanisms involved in angiogenesis in tumors, and how combination therapy to block DLL4-Notch signaling may enhance the efficacy of VEGF inhibitors, particularly in DLL4-upregulated tumors, and thus provide a rational base for the development of novel strategies to overcome antiangiogenic resistance in the clinic.

BRCA1 promoter methylation in peripheral blood DNA of mutation negative familial breast cancer patients with a BRCA1 tumour phenotype

Introduction

Individuals with germline mutations in the BRCA1 gene have an elevated risk of developing breast cancer, and often display characteristic clinicopathological features. We hypothesised that inactivation of BRCA1 by promoter methylation could occur as a germline or an early somatic event that predisposes to breast cancer with the phenotype normally associated with BRCA1 germline mutation.

Methods

We examined seven cases from breast-ovarian cancer families with tumours that showed BRCA1-like pathology but did not have detectable BRCA1 or BRCA2 germline mutations present. Methylation levels were tested by several quantitative techniques including MethyLight, methylation-sensitive high resolution melting (MS-HRM) and a newly developed digital MS-HRM assay.

Results

In one patient, methylation of 10% of the BRCA1 alleles was detected in the peripheral blood DNA, consistent with 20% of cells having one methylated allele. Buccal mucosa DNA from this individual displayed approximately 5% BRCA1 methylation. In two other patients, methylation of BRCA1 was detected in the peripheral blood at significantly lower but still readily detectable levels (approximately 1%). Tumour DNAs from these three patients were heavily methylated at BRCA1. The other patients had no detectable BRCA1 methylation in their peripheral blood. One of seven age-matched controls showed extremely low levels of methylation in their peripheral blood (approximately 0.1%).

Conclusion

These results demonstrate that in some cases of breast cancer, low-level promoter methylation of BRCA1 occurs in normal tissues of the body and is associated with the development of BRCA1-like breast cancer.

Suppressor of cytokine signaling 3 limits protection of leukemia inhibitory factor receptor signaling against central demyelination

Enhancement of oligodendrocyte survival through activation of leukemia inhibitory factor receptor (LIFR) signaling is a candidate therapeutic strategy for demyelinating disease. However, in other cell types, LIFR signaling is under tight negative regulation by the intracellular protein suppressor of cytokine signaling 3 (SOCS3). We, therefore, postulated that deletion of the SOCS3 gene in oligodendrocytes would promote the beneficial effects of LIFR signaling in limiting demyelination. By studying wild-type and LIF-knockout mice, we established that SOCS3 expression by oligodendrocytes was induced by the demyelinative insult, that this induction depended on LIF, and that endogenously produced LIF was likely to be a key determinant of the CNS response to oligodendrocyte loss. Compared with wild-type controls, oligodendrocyte-specific SOCS3 conditional-knockout mice displayed enhanced c-fos activation and exogenous LIF-induced phosphorylation of signal transducer and activator of transcription 3. Moreover, these SOCS3-deficient mice were protected against cuprizone-induced oligodendrocyte loss relative to wild-type animals. These results indicate that modulation of SOCS3 expression could facilitate the endogenous response to CNS injury.

SOCS3 negatively regulates LIF signaling in neural precursor cells

Cytokines that signal through the LIFRbeta/gp130 receptor complex, including LIF and CNTF, promote the self-renewal of embryonic and adult neural precursor cells (NPCs). In non-CNS tissues, the protein suppressor of cytokine signaling-3 (SOCS3) negatively regulates signaling through gp130. Here, we analyze the role of SOCS3 in inhibiting LIF signaling in NPCs in vitro. SOCS3 is rapidly expressed by NPCs in response to LIF stimulation, with this expression largely dependent on recruitment of STAT proteins to the activated gp130 receptor. Proliferating NPC cultures can be generated from SOCS3 knockout (SOCS3KO/KO) embryos and display prolonged STAT3 phosphorylation and induction of the GFAP gene in response to LIF. In comparison with SOCS3 wild-type (SOCS3WT/WT) NPCs, SOCS3KO/KO cultures display enhanced self-renewal capacity. However, the clonal potential of SOCS3WT/WT but not SOCS3KO/KO NPCs is enhanced by exogenous LIF. Thus, SOCS3 acts as a negative regulator of LIF signaling in NPCs.

Oligodendrocytes exhibit selective expression of suppressor of cytokine signaling genes and signal transducer and activator of transcription 1 independent inhibition of interferon-gamma-induced toxicity in response to leukemia inhibitory factor

Multiple sclerosis is an autoimmune disease of the CNS that results in the death of oligodendrocytes, the myelinating cells of the CNS. Previous studies have indicated that the cytokine leukemia inhibitory factor prevents the cytotoxic effects of interferon-gamma on oligodendrocytes in vitro, and the death of oligodendrocytes in an animal model of multiple sclerosis. Members of a recently characterized family of proteins, the suppressors of cytokine signaling, have been demonstrated to mediate negative cross-talk between cytokines, with induction of suppressors of cytokine signaling proteins by one cytokine inhibiting the activity of a second. Here, we assess whether induction of members of the suppressors of cytokine signaling family could explain the antagonistic biological effects of leukemia inhibitory factor and interferon-gamma upon oligodendrocytes. It is found that leukemia inhibitory factor rapidly and strongly induces the expression of suppressors of cytokine signaling-3 in cultured rat oligodendrocytes, whereas interferon-gamma weakly induces the expression of both suppressor of cytokine signaling-1 and 3. Pre-treatment of oligodendrocytes with leukemia inhibitory factor does not prevent the subsequent phosphorylation of signal transducer and activator of transcription-1 by interferon-gamma indicating that the leukemia inhibitory factor inhibition of interferon-gamma toxicity in oligodendrocytes is mediated by a suppressor of cytokine signaling-3 independent mechanism.

Minors' tobacco possession law violations and intentions to smoke: implications for tobacco control

OBJECTIVES

To test: (1) whether citation under the Minors in Possession (MIP) law, vicarious citation (knowing someone who was cited), and threat of driving licence suspension are associated with decreased intentions to smoke next year; and (2) whether the policy is differentially enforced.

SUBJECTS

28,249 white, Hispanic, and African American students in grades 6-12 (11-18 years old) participated in the study.

METHOD

The 86 item anonymous Texas Youth Tobacco Survey was completed by students attending 37 schools in 14 east and central Texas communities.

RESULTS

Hierarchical linear modelling showed that MIP citation was unrelated to the future smoking intentions of most youth. However, there was a negative association between citation and smoking intentions for ever daily smoking youth at four schools. Threat of licence suspension was associated with a lower likelihood of future smoking intentions among ever daily smoking youth and vicarious citation did not deter youth from future smoking. African American and Hispanic youth had a higher probability of being cited than their peers.

CONCLUSIONS

Threat of driving licence suspension has the intended effect upon youth who are/were committed smokers and MIP citation has the intended effect upon committed smokers at only four schools. However, differential enforcement of the law based on ethnicity may be occurring. Before drawing firm conclusions, current findings must be replicated with longitudinal data to determine the consequences of citation on subsequent tobacco use.

Caring in a Managed Care Environment-A Case Study in Teamwork

Level of care decisions in managed care require matching the patient's intensity of symptoms with the appropriate placement in the least restrictive setting. In planning appropriate treatment for a patient, the case manager at a managed care organization (MCO) considers "Why now?," examining the patient's diagnosis, as well as other pertinent factors, such as precipitant and the proximal cause for the patient's request for help. Team efforts between the MCO clinicians and the patient's treating clinicians improve the likelihood of patient/treatment outcome.

Structural and functional evidence for activation of a chick retinoid X receptor by eicosanoids

The retinoid X receptors (RXR-alpha, RXR-beta and RXR-gamma) are members of the steroid-thyroid hormone receptor superfamily of ligand-dependent transcription factors. They appear to function as auxiliary proteins that regulate high-affinity DNA binding and enhance transcriptional activity through heterodimer formation with other members of the superfamily. The RXR-alpha, RXR-beta and RXR-gamma proteins bind and are activated by the naturally occurring retinoid, 9-cis-retinoic acid. Structural similarities are apparent between retinoic acid and various eicosanoids, raising the possibility that eicosanoids may also activate retinoid receptors in vivo. We present evidence that lipoxygenase metabolites of arachidonic acid at submicromolar concentrations are capable of activating RXR-gamma activity in transient transfection assays. In addition, molecular modelling predicts conformational similarities between some lipoxygenase products and retinoic acid. Consistent with this, hydroxyeicosatetraenoic acids are known to mimic some actions of retinoids in cell-based assays. These observations raise the possibility that eicosanoids, already known to act both as local hormones and as intracellular second messengers, may also have a direct role in transcriptional activation via nuclear receptors.

Chromatin models. The ionic strength dependence of model histone-DNA interactions: circular dichroism studies of lysine-leucine polypeptide-DNA complexes

The ionic strength dependence of the complexes between DNA and both random, (Lysx, Leuy)n, and block copolymers, (Lysx)n(Leuy)m, of lysine and leucine, with different amino acid compositions, was studied using circular dichroism (CD) as the probe to detect conformational differences in these complexes relative to native DNA. It was found that the CD spectra of complexes of both the random (Lys84, Leu16)n and block (Lys85)n(Leu15)m copolymers with DNA show a very sharp ionic strength dependence. The maximum altered CD spectrum for the complexes with the block copolymer was found to occur at the same ionic strength as that for poly(L-lysine)-DNA complexes, while the maximum CD change for the random copolymer complex occurred at a slightly lower ionic strength. This sharp dependence of the CD change on the ionic strength was found to be independent of the polymer/DNA ratio, r, for each individual copolymer. The CD spectra for these complexes at optimum NaCl concentration resemble those of the psi spectra of DNA [Jordan, C. F., Lerman, L.S., and Venable, J.H. (1972), Nature (London), New Biol. 236, 67]. The complexes of the random copolymer, (Lys68, Leu32)n, with DNA (r=0.25) at 0.15 M NaCl and below have CD spectra that resemble the A-form DNA spectra. The ionic strength dependence of the CD spectra of this complex is not as sharp as observed with the above polymers and has a broad positive plateau. It is suggested that both the CD spectra of these complexes reflect the phenomena of DNA condensation into a higher order asymmetric structure (folded and compact). The block copolymer, (Lys77)n(Leu23)m, complexes with DNA show very slight alterations in the CD spectra, with respect to native DNA. It appears that the long Leu sequence at one end of such copolymers may be unpropitious for causing the polypeptide-DNA complex to condense into a higher order asymmetric structure. Thus the importance of the distribution of hydrophobic residues, in the copolypeptides of Lys, is shown for causing condensation of complexes with DNA. The relevance of these findings to histone-DNA complexes in chromatin is discussed.