LRG1 destabilizes tumor vessels and restricts immunotherapeutic potency

BACKGROUND: A poorly functioning tumor vasculature is pro-oncogenic and may impede the delivery of therapeutics. Normalizing the vasculature, therefore, may be beneficial. We previously reported that the secreted glycoprotein leucine-rich α-2-glycoprotein 1 (LRG1) contributes to pathogenic neovascularization. Here, we investigate whether LRG1 in tumors is vasculopathic and whether its inhibition has therapeutic utility. METHODS: Tumor growth and vascular structure were analyzed in subcutaneous and genetically engineered mouse models in wild-type and Lrg1 knockout mice. The effects of LRG1 antibody blockade as monotherapy, or in combination with co-therapies, on vascular function, tumor growth, and infiltrated lymphocytes were investigated. FINDINGS: In mouse models of cancer, Lrg1 expression was induced in tumor endothelial cells, consistent with an increase in protein expression in human cancers. The expression of LRG1 affected tumor progression as Lrg1 gene deletion, or treatment with a LRG1 function-blocking antibody, inhibited tumor growth and improved survival. Inhibition of LRG1 increased endothelial cell pericyte coverage and improved vascular function, resulting in enhanced efficacy of cisplatin chemotherapy, adoptive T cell therapy, and immune checkpoint inhibition (anti-PD1) therapy. With immunotherapy, LRG1 inhibition led to a significant shift in the tumor microenvironment from being predominantly immune silent to immune active. CONCLUSIONS: LRG1 drives vascular abnormalization, and its inhibition represents a novel and effective means of improving the efficacy of cancer therapeutics

LRG1 destabilizes tumor vessels and restricts immunotherapeutic potency

Background: A poorly functioning tumor vasculature is pro-oncogenic and may impede the delivery of therapeutics. Normalizing the vasculature, therefore, may be beneficial. We previously reported that the secreted glycoprotein leucine-rich α-2-glycoprotein 1 (LRG1) contributes to pathogenic neovascularization. Here, we investigate whether LRG1 in tumors is vasculopathic and whether its inhibition has therapeutic utility. Methods: Tumor growth and vascular structure were analyzed in subcutaneous and genetically engineered mouse models in wild-type and Lrg1 knockout mice. The effects of LRG1 antibody blockade as monotherapy, or in combination with co-therapies, on vascular function, tumor growth, and infiltrated lymphocytes were investigated. Findings: In mouse models of cancer, Lrg1 expression was induced in tumor endothelial cells, consistent with an increase in protein expression in human cancers. The expression of LRG1 affected tumor progression as Lrg1 gene deletion, or treatment with a LRG1 function-blocking antibody, inhibited tumor growth and improved survival. Inhibition of LRG1 increased endothelial cell pericyte coverage and improved vascular function, resulting in enhanced efficacy of cisplatin chemotherapy, adoptive T cell therapy, and immune checkpoint inhibition (anti-PD1) therapy. With immunotherapy, LRG1 inhibition led to a significant shift in the tumor microenvironment from being predominantly immune silent to immune active. Conclusions: LRG1 drives vascular abnormalization, and its inhibition represents a novel and effective means of improving the efficacy of cancer therapeutics. Funding: Wellcome Trust (206413/B/17/Z), UKRI/MRC (G1000466, MR/N006410/1, MC/PC/14118, and MR/L008742/1), BHF (PG/16/50/32182), Health and Care Research Wales (CA05), CRUK (C42412/A24416 and A17196), ERC (ColonCan 311301 and AngioMature 787181), and DFG (CRC1366)

Acquired resistance to oxaliplatin is not directly associated with increased resistance to DNA damage in SK-N-ASrOXALI4000, a newly established oxaliplatin-resistant sub-line of the neuroblastoma cell line SK-N-AS

The formation of acquired drug resistance is a major reason for the failure of anti-cancer therapies after initial response. Here, we introduce a novel model of acquired oxaliplatin resistance, a sub-line of the non-MYCN-amplified neuroblastoma cell line SK-N-AS that was adapted to growth in the presence of 4000 ng/mL oxaliplatin (SK-N-ASrOXALI4000). SK-N-ASrOXALI4000 cells displayed enhanced chromosomal aberrations compared to SK-N-AS, as indicated by 24-chromosome fluorescence in situ hybridisation. Moreover, SK-N-ASrOXALI4000 cells were resistant not only to oxaliplatin but also to the two other commonly used anti-cancer platinum agents cisplatin and carboplatin. SK-N-ASrOXALI4000 cells exhibited a stable resistance phenotype that was not affected by culturing the cells for 10 weeks in the absence of oxaliplatin. Interestingly, SK-N-ASrOXALI4000 cells showed no cross resistance to gemcitabine and increased sensitivity to doxorubicin and UVC radiation, alternative treatments that like platinum drugs target DNA integrity. Notably, UVC-induced DNA damage is thought to be predominantly repaired by nucleotide excision repair and nucleotide excision repair has been described as the main oxaliplatin-induced DNA damage repair system. SK-N-ASrOXALI4000 cells were also more sensitive to lysis by influenza A virus, a candidate for oncolytic therapy, than SK-N-AS cells. In conclusion, we introduce a novel oxaliplatin resistance model. The oxaliplatin resistance mechanisms in SK-N-ASrOXALI4000 cells appear to be complex and not to directly depend on enhanced DNA repair capacity. Models of oxaliplatin resistance are of particular relevance since research on platinum drugs has so far predominantly focused on cisplatin and carboplatin

Association of the M1V PRKAR1A Mutation with Primary Pigmented Nodular Adrenocortical Disease in Two Large Families

Background: Carney complex (CNC) is a familial multiple neoplasia syndrome frequently associated with primary pigmented nodular adrenocortical disease (PPNAD), a bilateral form of micronodular adrenal hyperplasia that leads to Cushing’s syndrome (CS). Germline PRKAR1A mutations cause CNC and only rarely isolated PPNAD

Representative fluorescence in situ hybridisation (FISH) images of chromosomes 2 (A, D and G), 12 (B, E and H) and 8 (C, F and I) in SK-N-AS (A-C), SK-N-ASrOALI4000(-) (D-F), and SK-N-ASrOXALI4000 (G-I) neuroblastoma cells.

<p>Scale bar represents 10μm.</p

Phosphorylation status of 49 receptor tyrosine kinases.

<p>Receptor tyrosine kinase phosphorylation was determined by a commercial kit (Proteome Profiler Human Phospho-RTK Array Kit, R&D Systems, Abingdon, UK) with subsequent densitometric analysis using ImageJ software (<a href="http://imagej.nih.gov/ij/" target="_blank">http://imagej.nih.gov/ij/</a>). A) Receptor tyrosine kinase phosphorylation status expressed as fold change spot density relative to a control membrane area. Images of the membranes are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172140#pone.0172140.s001" target="_blank">S1 Fig</a>. B) Differential phosphorylation of receptor tyrosine kinases that were found phosphorylated in at least one cell line (as indicated by a fold change spot density relative to a control membrane area >2) in SK-N-AS^rOXALI⁴⁰⁰⁰ or SK-N-AS^rOXALI^4000(-) cells relative to SK-N-AS.</p

Effects of H1N1 influenza A virus infection on cell viability.

<p>Non-MYCN-amplified SK-N-AS neuroblastoma cells, SK-N-AS cells with acquired resistance to oxaliplatin (SK-N-AS^rOXALI⁴⁰⁰⁰), SK-N-AS^rOXALI⁴⁰⁰⁰ cells that were passaged for 10 passages in absence of oxaliplatin (SK-N-AS^rOXALI^4000(-)), or MYCN-amplified UKF-NB-3 neuroblastoma cells were infected with H1N1 influenza strain A/WSN/33 virus at different multiplicities of infection (MOIs) and cell viability was determined 48h post infection relative to non-treated control. The dotted line indicates the viability of non-infected control cells. * P < 0.05 relative to non-infected control cells.</p

Oxygen consumption by SK-N-AS and SK-N-AS^rOXALI⁴⁰⁰⁰ cells.

<p>Oxygen consumption was determined in intact cells in the absence of treatment (baseline), in response to oligomycin (8 μg/mL), an inhibitor of ATP synthase that causes a leak of protons resulting in inhibition of respiration (leak), and in response to FCCP (10 μM) that uncouples the electron transport chain resulting in maximum oxidative phosphorylation.</p