Rapid point-of-care detection of SARS-CoV-2 infection in exhaled breath using ion mobility spectrometry: a pilot study

BACKGROUND

An effective testing strategy is essential for pandemic control of the novel Coronavirus disease 2019 (COVID-19) caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Breath gas analysis can expand the available toolbox for diagnostic tests by using a rapid, cost-beneficial, high-throughput point-of-care test. We conducted a bi-center clinical pilot study in Germany to evaluate breath gas analysis using multi-capillary column ion mobility spectrometry (MCC-IMS) to detect SARS-CoV-2 infection.

METHODS

Between September 23, 2020, and June 11, 2021, breath gas measurements were performed on 380 patients (SARS-CoV-2 real-time polymerase chain reaction (PCR) positive: 186; PCR negative: 194) presenting to the emergency department (ED) with respiratory symptoms.

RESULTS

Breath gas analysis using MCC-IMS identified 110 peaks; 54 showed statistically significant differences in peak intensity between the SARS-CoV-2 PCR-negative and PCR-positive groups. A decision tree analysis classification resulted in a sensitivity of 83% and specificity of 86%, but limited robustness to dataset changes. Modest values for the sensitivity (74%) and specificity (52%) were obtained using linear discriminant analysis. A systematic search for peaks led to a sensitivity of 77% and specificity of 67%; however, validation by transferability to other data is questionable.

CONCLUSIONS

Despite identifying several peaks by MCC-IMS with significant differences in peak intensity between PCR-negative and PCR-positive samples, finding a classification system that allows reliable differentiation between the two groups proved to be difficult. However, with some modifications to the setup, breath gas analysis using MCC-IMS may be a useful diagnostic toolbox for SARS-CoV-2 infection.

TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov on September 21, 2020 (NCT04556318; Study-ID: HC-N-H-2004).

NUMB as a Therapeutic Target for Melanoma

The upregulation of the adaptor protein NUMB triggers melanocytic differentiation from multipotent skin stem cells, which share many properties with aggressive melanoma cells. Although NUMB acts as a tumor suppressor in various human cancer types, little is known about its role in melanoma. In this study, we investigated the role of NUMB in melanoma progression and its regulatory mechanism. Analysis of The Cancer Genome Atlas melanoma datasets revealed that high NUMB expression in melanoma tissues correlates with improved patient survival. Moreover, NUMB expression is downregulated in metastatic melanoma cells. NUMB knockdown significantly increased the invasion potential of melanoma cells in a three-dimensional collagen matrix in vitro and in the lungs of a mouse model in vivo; it also significantly upregulated the expression of the NOTCH target gene CCNE. Previous studies suggested that Wnt signaling increases NUMB expression. By mimicking Wnt stimulation through glycogen synthase kinase-3 inhibition, we increased NUMB expression in melanoma cells. Furthermore, a glycogen synthase kinase-3 inhibitor reduced the invasion of melanoma cells in a NUMB-dependent manner. Together, our results suggest that NUMB suppresses invasion and metastasis in melanoma, potentially through its regulation of the NOTCH‒CCNE axis and that the inhibitors that upregulate NUMB can exert therapeutic effects in melanoma.

Tumor-B-cell interactions promote isotype switching to an immunosuppressive IgG4 antibody response through upregulation of IL-10 in triple negative breast cancers

Background

Triple negative breast cancer (TNBC) is an aggressive breast cancer for which there is currently no targeted therapy. Tumor-infiltrating B-cells (TIB) have been observed in tumor tissues of TNBC patients, but their functional role is unclear. IgG4 is one of four antibody subclasses of IgG expressed and secreted by B cells. Unlike other IgG isotypes, IgG4 has an immunosuppressive function and is induced by Th2-type cytokines. In cancers such as melanoma, IgG4 has been linked with advanced disease and poor patient survival. Therefore, we sought to determine if IgG4 + B cells are present and determine the mechanisms driving isotype switching in TNBC.

Methods

We performed co-culture assays to examine expression of Th2 cytokines by TNBC cells with and without the presence of B cells. We also performed in vitro class switching experiments with peripheral B cells with and without co-culture with TNBC cells in the presence or absence of an IL-10 blocking antibody. We examined expression of CD20+ TIB, IgG4 and Th2 cytokines by immunohistochemistry in 152 TNBC samples. Statistical analysis was done using Log-Rank and Cox-proportional hazards tests.

Results

Our findings indicate that B cells interact with TNBC to drive chronic inflammatory responses through increased expression of inflammatory cytokines including the TH2 cytokines IL-4 and IL-10. In vitro class switching studies show that interactions between TNBC cell lines and B cells drive isotype switching to the IgG4 isotype in an IL-10 dependent manner. In patient tissues, expression of IgG4 correlates with CD20 and tumor expression of IL-10. Both IgG4 and tumor IL-10 are associated to shorter recurrence free survival (RFS) and overall survival (OS) in TNBC. In a multi-variant analysis, IL-10 was associated with poor outcomes indicating that tumor IL-10 may drive immune escape.

Conclusions

These findings indicate that interactions between TIB and TNBC results in activation of chronic inflammatory signals such as IL-10 and IL-4 that drive class switching to an IgG4 + subtype which may suppress antibody driven immune responses. The presence of IgG4 + B cells may serve as a biomarker for poor prognosis.

Costimulation of γδTCR and TLR7/8 promotes Vδ2 T-cell antitumor activity by modulating mTOR pathway and APC function

Background

Gamma delta (γδ) T cells are attractive effector cells for cancer immunotherapy. Vδ2 T cells expanded by zoledronic acid (ZOL) are the most commonly used γδ T cells for adoptive cell therapy. However, adoptive transfer of the expanded Vδ2 T cells has limited clinical efficacy.

Methods

We developed a costimulation method for expansion of Vδ2 T cells in PBMCs by activating γδ T-cell receptor (γδTCR) and Toll-like receptor (TLR) 7/8 using isopentenyl pyrophosphate (IPP) and resiquimod, respectively, and tested the functional markers and antitumoral effects in vitro two-dimensional two-dimensional and three-dimensional spheroid models and in vivo models. Single-cell sequencing dataset analysis and reverse-phase protein array were employed for mechanistic studies.

Results

We find that Vδ2 T cells expanded by IPP plus resiquimod showed significantly increased cytotoxicity to tumor cells with lower programmed cell death protein 1 (PD-1) expression than Vδ2 T cells expanded by IPP or ZOL. Mechanistically, the costimulation enhanced the activation of the phosphatidylinositol 3-kinase (PI3K)–protein kinase B (PKB/Akt)–the mammalian target of rapamycin (mTOR) pathway and the TLR7/8–MyD88 pathway. Resiquimod stimulated Vδ2 T-cell expansion in both antigen presenting cell dependent and independent manners. In addition, resiquimod decreased the number of adherent inhibitory antigen-presenting cells (APCs) and suppressed the inhibitory function of APCs by decreasing PD-L1 and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) expression in these cells during in vitro Vδ2 T-cell expansion. Finally, we showed that human Vδ2 T cells can be expanded from PBMCs and spleen of humanized NSG mice using IPP plus resiquimod or ZOL, demonstrating that humanized mice are a promising preclinical model for studying human γδ T-cell development and function.

Conclusions

Vδ2 T cells expanded by IPP and resiquimod demonstrate improved anti-tumor function and have the potential to increase the efficacy of γδ T cell-based therapies.

Neural Crest-Like Stem Cell Transcriptome Analysis Identifies LPAR1 in Melanoma Progression and Therapy Resistance

Metastatic melanoma is challenging to clinically address. Although standard-of-care targeted therapy has high response rates in patients with BRAF-mutant melanoma, therapy relapse occurs in most cases. Intrinsically resistant melanoma cells drive therapy resistance and display molecular and biologic properties akin to neural crest-like stem cells (NCLSC) including high invasiveness, plasticity, and self-renewal capacity. The shared transcriptional programs and vulnerabilities between NCLSCs and cancer cells remains poorly understood. Here, we identify a developmental LPAR1-axis critical for NCLSC viability and melanoma cell survival. LPAR1 activity increased during progression and following acquisition of therapeutic resistance. Notably, genetic inhibition of LPAR1 potentiated BRAFi ± MEKi efficacy and ablated melanoma migration and invasion. Our data define LPAR1 as a new therapeutic target in melanoma and highlights the promise of dissecting stem cell-like pathways hijacked by tumor cells. SIGNIFICANCE: This study identifies an LPAR1-axis critical for melanoma invasion and intrinsic/acquired therapy resistance.

Challenges in the humanized mouse model for cancer: A commentary

The complexity of the tumor microenvironment has been a challenge for understanding the mechanisms of therapy resistance. The development of improved animal models that closely mimic human disease is key for understanding and treating diseases. Recently, a new humanized mouse model has been developed that enables the study of human immune cells in tumor host-cell interactions. In this commentary we highlight the critical aspects of mast cells in immune therapy resistance. These mast cells release cytokines that downmodulate HLA class I on the malignant cells making them inaccessible the cytotoxic activity of T cells.

Immunotargeting of tumor subpopulations in melanoma patients: A paradigm shift in therapy approaches

Several melanoma cell subpopulations with tumor-initiating and/or tumor-maintaining properties exist that may contribute to chemoresistance and tumor recurrence after standard therapies. One of these subpopulations expresses a B-cell marker, CD20. In a small pilot trial, we showed that a subset of Stage IV melanoma patients may potentially benefit from an adjuvant treatment using the anti-CD20 antibody rituximab.

Tumor-infiltrating mast cells are associated with resistance to anti-PD-1 therapy

Anti-PD-1 therapy is used as a front-line treatment for many cancers, but mechanistic insight into this therapy resistance is still lacking. Here we generate a humanized (Hu)-mouse melanoma model by injecting fetal liver-derived CD34⁺ cells and implanting autologous thymus in immune-deficient NOD-scid IL2Rγ^null (NSG) mice. Reconstituted Hu-mice are challenged with HLA-matched melanomas and treated with anti-PD-1, which results in restricted tumor growth but not complete regression. Tumor RNA-seq, multiplexed imaging and immunohistology staining show high expression of chemokines, as well as recruitment of FOXP3⁺ Treg and mast cells, in selective tumor regions. Reduced HLA-class I expression and CD8⁺/Granz B⁺ T cells homeostasis are observed in tumor regions where FOXP3⁺ Treg and mast cells co-localize, with such features associated with resistance to anti-PD-1 treatment. Combining anti-PD-1 with sunitinib or imatinib results in the depletion of mast cells and complete regression of tumors. Our results thus implicate mast cell depletion for improving the efficacy of anti-PD-1 therapy.

Immune checkpoint therapies (ICT) are promising for treating various cancers, but response rates vary. Here the authors show, in mouse models, that tumor-infiltrating mast cells colocalize with regulatory T cells, coincide with local reduction of MHC-I and CD8 T cells, and is associated with resistance to ICT, which can be reversed by c-kit inhibitor treatment.

RETRACTED ARTICLE: IspH inhibitors kill Gram-negative bacteria and mobilize immune clearance

Isoprenoids are vital to all organisms in supporting core functions of life, like respiration and membrane stability.¹ IspH, an enzyme in the methyl erythritol phosphate pathway of isoprenoid synthesis, is essential to gram-negative bacteria, mycobacteria and apicomplexans.^2,3 The IspH substrate, HMBPP, is not produced in humans and other metazoans and activates cytotoxic Vγ9Vδ2 T-cells in humans and primates at extremely low concentrations.^4-6 We describe novel IspH inhibitors and through structure-guided analog design, refine their potency to nanomolar levels. We have modified these into prodrugs for delivery into bacteria and report that they kill clinical isolates of several multidrug resistant bacterial species such as Acinetobacter, Pseudomonas, Klebsiella, Enterobacter, Vibrio, Shigella, Salmonella, Yersinia, Mycobacterium and Bacillus, while being relatively non-toxic to mammalian cells. Proteomic analysis reveals that bacteria treated with prodrugs resemble those with conditional IspH knockdown. Notably, these prodrugs also cause expansion and activation of human Vγ9Vδ2 T-cells in a humanized mouse model of bacterial infection. These IspH prodrugs synergize direct antibiotic killing with a simultaneous rapid immune response by cytotoxic γδ T-cells, which may limit the rise of antibiotic resistant bacterial populations.

ARID2 Deficiency Correlates with the Response to Immune Checkpoint Blockade in Melanoma

The SWI/SNF chromatin remodeler family includes the BAF and PBAF complexes. ARID2, encoding a PBAF complex subunit, is frequently mutated in melanoma independently of BRAF/RAS mutations. Emerging evidence shows that SWI/SNF complexes regulate tumor immunity; for instance, the loss of PBRM1, another PBAF complex subunit, enhances susceptibility to immune checkpoint inhibitors in melanoma. Notably, ARID2 mutations are more frequent in melanoma than PBRM1 mutations. However, the role of ARID2 as a modulator of tumor immunity remains unclear. In this study, we show that ARID2 knockout sensitizes melanoma to immune checkpoint inhibitors. Anti‒PD-L1 treatment restricts tumor growth in mice bearing ARID2-knockout melanoma cells, correlating with an increase in the infiltration of cytotoxic CD8⁺ T cells. Furthermore, ARID2 deficiency leads to signal transducer and activator of transcription 1 upregulation, which subsequently causes increased expression of T-cell‒attracting chemokines such as CXCL9, CXCL10, and CCL5. These results demonstrate that ARID2 is an immunomodulator and a potential biomarker that indicates immune checkpoint inhibitor effectiveness in patients with melanoma.

Abstract A26: Humanized mouse model: A model to understand mechanisms of immune non-responsiveness to immune checkpoint inhibitors in melanoma

Immune checkpoint inhibitor therapy (anti-CTLA4 or anti-PD1 antibodies) is rapidly emerging as a front-line treatment option for many solid tumors. However, only a third of melanoma patients respond to immune checkpoint blockade. Currently available mouse xenograft and transgenic models have many shortcomings and are unable to address the basis of therapy resistance and immune nonresponsiveness that are observed in patients. Thus, there is an urgent need to establish an in vivo model with a human immune microenvironment that can address issues of therapy resistance. Our laboratory has developed a novel humanized mouse melanoma model. Immunodeficient NSG mice were reconstituted with human CD34+ cells and after 8-12 weeks, mice are fully reconstituted with human innate (monocyte/myeloid lineage cells, dendritic cells and NK cells) and adaptive (T and B cells) immune cells. Humanized mice were then challenged with HLA-matched melanoma cells, and the functional ability of human immune cells to restrict tumor growth was monitored. Delayed tumor growth was observed in humanized mice, indicating in vivo sensitization of human immune cells to melanoma. This was confirmed by in vitro demonstration of human lymphocytes from tumor-bearing mice showing enhanced cytokine expression after stimulation with melanoma antigen peptides. In therapy studies, tumor-bearing humanized mice treated with anti-PD-1 showed restricted tumor growth. Anti-PD-1 therapy resulted in enhanced infiltration of T cells that correlated with tumor response. MassCyTOF studies were performed using a panel of immune markers to understand the mechanism of therapy nonresponsiveness in some tumors. Downmodulation of HLA-class I molecules and increased presence of FOXP3+ cells in the tumor region were seen. Our results suggest that humanized mouse melanoma model can be explored further to understand the causes of therapy resistance and immune nonresponsiveness.

Citation Format: Rajasekharan Somasundaram, Anastasia Samarkina, Thomas Connelly, Robin Choi, Hedy Choi, Kar Muthumani, Xiaowei Xu, Klaus Kaestner, Meenhard Herlyn. Humanized mouse model: A model to understand mechanisms of immune non-responsiveness to immune checkpoint inhibitors in melanoma [abstract]. In: Proceedings of the AACR Special Conference on Melanoma: From Biology to Target; 2019 Jan 15-18; Houston, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(19 Suppl):Abstract nr A26.

Pre-clinical modeling of cutaneous melanoma

Metastatic melanoma is challenging to manage. Although targeted- and immune therapies have extended survival, most patients experience therapy resistance. The adaptability of melanoma cells in nutrient- and therapeutically-challenged environments distinguishes melanoma as an ideal model for investigating therapy resistance. In this review, we discuss the current available repertoire of melanoma models including two- and three-dimensional tissue cultures, organoids, genetically engineered mice and patient-derived xenograft. In particular, we highlight how each system recapitulates different features of melanoma adaptability and can be used to better understand melanoma development, progression and therapy resistance.

Despite the new targeted and immunotherapies for metastatic melanoma, several patients show therapeutic plateau. Here, the authors review the current pre-clinical models of cutaneous melanoma and discuss their strengths and limitations that may help with overcoming therapeutic plateau.

B cells sustain inflammation and predict response to immune checkpoint blockade in human melanoma

Tumor associated inflammation predicts response to immune checkpoint blockade in human melanoma. Current theories on regulation of inflammation center on anti-tumor T cell responses. Here we show that tumor associated B cells are vital to melanoma associated inflammation. Human B cells express pro- and anti-inflammatory factors and differentiate into plasmablast-like cells when exposed to autologous melanoma secretomes in vitro. This plasmablast-like phenotype can be reconciled in human melanomas where plasmablast-like cells also express T cell-recruiting chemokines CCL3, CCL4, CCL5. Depletion of B cells in melanoma patients by anti-CD20 immunotherapy decreases tumor associated inflammation and CD8+ T cell numbers. Plasmablast-like cells also increase PD-1+ T cell activation through anti-PD-1 blockade in vitro and their frequency in pretherapy melanomas predicts response and survival to immune checkpoint blockade. Tumor associated B cells therefore orchestrate and sustain melanoma inflammation and may represent a predictor for survival and response to immune checkpoint blockade therapy.

Co-targeting BET and MEK as salvage therapy for MAPK and checkpoint inhibitor-resistant melanoma

Despite novel therapies for melanoma, drug resistance remains a significant hurdle to achieving optimal responses. NRAS‐mutant melanoma is an archetype of therapeutic challenges in the field, which we used to test drug combinations to avert drug resistance. We show that BET proteins are overexpressed in NRAS‐mutant melanoma and that high levels of the BET family member BRD4 are associated with poor patient survival. Combining BET and MEK inhibitors synergistically curbed the growth of NRAS‐mutant melanoma and prolonged the survival of mice bearing tumors refractory to MAPK inhibitors and immunotherapy. Transcriptomic and proteomic analysis revealed that combining BET and MEK inhibitors mitigates a MAPK and checkpoint inhibitor resistance transcriptional signature, downregulates the transcription factor TCF19, and induces apoptosis. Our studies demonstrate that co‐targeting MEK and BET can offset therapy resistance, offering a salvage strategy for melanomas with no other therapeutic options, and possibly other treatment‐resistant tumor types.

Age Correlates with Response to Anti-PD1, Reflecting Age-Related Differences in Intratumoral Effector and Regulatory T-Cell Populations

Purpose: We have shown that the aged microenvironment increases melanoma metastasis, and decreases response to targeted therapy, and here we queried response to anti-PD1.Experimental Design: We analyzed the relationship between age, response to anti-PD1, and prior therapy in 538 patients. We used mouse models of melanoma, to analyze the intratumoral immune microenvironment in young versus aged mice and confirmed our findings in human melanoma biopsies.Results: Patients over the age of 60 responded more efficiently to anti-PD-1, and likelihood of response to anti-PD-1 increased with age, even when we controlled for prior MAPKi therapy. Placing genetically identical tumors in aged mice (52 weeks) significantly increased their response to anti-PD1 as compared with the same tumors in young mice (8 weeks). These data suggest that this increased response in aged patients occurs even in the absence of a more complex mutational landscape. Next, we found that young mice had a significantly higher population of regulatory T cells (Tregs), skewing the CD8+:Treg ratio. FOXP3 staining of human melanoma biopsies revealed similar increases in Tregs in young patients. Depletion of Tregs using anti-CD25 increased the response to anti-PD1 in young mice.Conclusions: While there are obvious limitations to our study, including our inability to conduct a meta-analysis due to a lack of available data, and our inability to control for mutational burden, there is a remarkable consistency in these data from over 500 patients across 8 different institutes worldwide. These results stress the importance of considering age as a factor for immunotherapy response. Clin Cancer Res; 24(21); 5347-56. ©2018 AACR See related commentary by Pawelec, p. 5193.

Remodeling of the Collagen Matrix in Aging Skin Promotes Melanoma Metastasis and Affects Immune Cell Motility

Physical changes in skin are among the most visible signs of aging. We found that young dermal fibroblasts secrete high levels of extracellular matrix (ECM) constituents, including proteoglycans, glycoproteins, and cartilage-linking proteins. The most abundantly secreted was HAPLN1, a hyaluronic and proteoglycan link protein. HAPLN1 was lost in aged fibroblasts, resulting in a more aligned ECM that promoted metastasis of melanoma cells. Reconstituting HAPLN1 inhibited metastasis in an aged microenvironment, in 3-D skin reconstruction models, and in vivo. Intriguingly, aged fibroblast-derived matrices had the opposite effect on the migration of T cells, inhibiting their motility. HAPLN1 treatment of aged fibroblasts restored motility of mononuclear immune cells, while impeding that of polymorphonuclear immune cells, which in turn affected regulatory T-cell recruitment. These data suggest that although age-related physical changes in the ECM can promote tumor cell motility, they may adversely affect the motility of some immune cells, resulting in an overall change in the immune microenvironment. Understanding the physical changes in aging skin may provide avenues for more effective therapy for older patients with melanoma. SIGNIFICANCE: These data shed light on the mechanochemical interactions that occur between aged skin, tumor, and immune cell populations, which may affect tumor metastasis and immune cell infiltration, with implications for the efficacy of current therapies for melanoma.See related commentary by Marie and Merlino, p. 19.This article is highlighted in the In This Issue feature, p. 1.

Exosomal PD-L1 contributes to immunosuppression and is associated with anti-PD-1 response

Tumour cells evade immune surveillance by upregulating the surface expression of programmed death-ligand 1 (PD-L1), which interacts with programmed death-1 (PD-1) receptor on T cells to elicit the immune checkpoint response1,2. Anti-PD-1 antibodies have shown remarkable promise in treating tumours, including metastatic melanoma2-4. However, the patient response rate is low4,5. A better understanding of PD-L1-mediated immune evasion is needed to predict patient response and improve treatment efficacy. Here we report that metastatic melanomas release extracellular vesicles, mostly in the form of exosomes, that carry PD-L1 on their surface. Stimulation with interferon-γ (IFN-γ) increases the amount of PD-L1 on these vesicles, which suppresses the function of CD8 T cells and facilitates tumour growth. In patients with metastatic melanoma, the level of circulating exosomal PD-L1 positively correlates with that of IFN-γ, and varies during the course of anti-PD-1 therapy. The magnitudes of the increase in circulating exosomal PD-L1 during early stages of treatment, as an indicator of the adaptive response of the tumour cells to T cell reinvigoration, stratifies clinical responders from non-responders. Our study unveils a mechanism by which tumour cells systemically suppress the immune system, and provides a rationale for the application of exosomal PD-L1 as a predictor for anti-PD-1 therapy.

Abstract LB-350: IgG4 expressing B cells associate with poor survival in triple negative breast cancer

Triple negative breast cancer (TNBC) is an aggressive form of breast cancer with high levels of lymphocyte infiltration. Although high levels of infiltrating B cells are present in TNBC, their role in progression of this disease is unclear. IgG4 is one of four subclasses of IgG and is the least abundant in healthy human serum. IgG4 has been found at higher percentages in both tissue and serum in cases of chronic inflammation, which promotes class switching to IgG4. Expression and secretion of IgG4 by B cells may be non-beneficial and potentially harmful in the cancer setting. Unlike the other subclasses of IgG, IgG4 does not activate complement dependent cytotoxicity and has a lower affinity for FcγR, thus resulting in a poor ability to engage immune effector cells and activate antibody-depended cell-mediated cytotoxicity. Additionally, IgG4 can compete with other IgG subclasses by binding to antigens and can sequestering IgG through Fc-Fc interactions, thus impairing potential anti-tumor antibody-mediated responses. As IgG4 expressing B cells have been shown to be associated with poor outcomes in other aggressive cancers such melanoma, glioblastoma and pancreatic cancer, we sought to determine the expression of IgG4 in TNBC. We performed immunohistological staining of IgG4 in paraffin-embedded tissue microarrays from 75 treatment-naive TNBC specimens obtained from women who underwent surgical resection of their tumors at the Helen F Graham Cancer Center and Research Institute from 2006-2007. We found that 69 % of TNBC cases contain IgG4+ cell infiltration. Moreover, the presence of IgG4+ cells is significantly correlated with poorer progression free (p<0.0003) and overall survival (p<0.0001) as determined by a Log-rank (Mantel-Cox) test. These findings indicate the presence of an immunosuppressive B cell population. Further study is needed to characterize these cells and to determine the significance of IgG4+ tumor infiltrating B cells, and their potential immunosuppressive role in the progression of TNBC.

Citation Format: Nicole Flynn, Ugochukwu Amadi, Rajasekharan Somasundaram, Jennifer Sims-Mourtada. IgG4 expressing B cells associate with poor survival in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-350.

Abstract 5833: Escape form adaptive drug tolerance through OGT and TET1 mediated H3K4me3 remodeling in MAPKi resistant melanoma

Background Acquired drug resistance in BRAF mutant melanoma is the main cause for disease relapse. We previously described a slow cycling induced drug tolerant state upon continuous BRAF/MEK treatment preceding permanent resistance with generic changes in histone methylation. Rationale Genetic alterations linked to acquired BRAF inhibitor resistance are absent in about 40% of relapsed melanoma patients suggesting the involvement of epigenetic alterations in the development of acquired drug resistance. We investigated epigenetic remodeling in BRAF mutant melanoma upon BRAF/MEK inhibition. Methods An in-vitro model of time lapse dependent transition to acquired drug resistance using mutant BRAF melanoma was used to investigate epigenetic changes following chronic drug exposure. Histone methylation patters were investigated using ChIP-seq, followed by target gene promoter ChIP-PCR and functional verification. Findings were confirmed by gene silencing, combined treatment regimes in vivo, in PDX tumors and clinical data sets. Results A state dependent response to chronic drug treatment was observed. Long term treatment of more than 45 days enables the cells to escape the slow cycling state which results in proliferating cellular clusters (drug-tolerant persister colonies) with stem-like characteristics that regain global H3K4me3. Persister colonies are then giving rise to fast proliferating BRAF/MEK inhibitor resistant cells. H3K4me3 ChIP-seq of colonies compared to parental cells revealed differential marking at promotor regions of several target genes involved in MAPKi resistance, including ARAF, BRAF, and CRAF. H3K4me3 remodeling corresponded to increased gene expression and susceptibility to pan-RAF inhibitors, suggesting an H3K4me3 mediated increase of ARAF and CRAF as a mechanism of BRAF/MEK inhibitor resistance. Two enzymes, OGT and TET1 that are both linked to H3K4me3 regulation in embryonic stem cells are highly upregulated in persister colonies and tumor tissue of PDXs from BRAF mutant melanoma patients under MEK1/2 inhibition. A shift in OGT nuclear localization and O-linked glycosylation patterns was observed in colonies compared to parental cells suggestive of altered transcriptional and protein activity. OGT ChIP-PCR of colonies compared to parental cells confirmed a set of genes with exclusively H3K4me3 marking in colonies. shRNA mediated knockdown of OGT and TET1 blocked H3K4me3 increase in IDTC colonies, prevented colony formation and delayed tumor relapse in a BRAF mutant xenograft mouse model. High TET1 mRNA expression is linked to significantly shorter survival in TGCA data. Conclusion OGT and TET1 mediated epigenetic remodeling through H3K4me3 with upregulation of MAPKi resistant genes is responsible for the emergence of permanent resistance. Both enzymes are promising targets to combat treatment failure and prolong overall survival.

Citation Format: Dinoop Ravindran Menon, Heinz Hammerlindl, Abdullah Al Emran, Joachim Torrano, Sabrina Hammerlindl, Gao Zhang, Rajasekharan Somasundaram, Richard A. Sturm, Nikolas K. Haass, Keith Flaherty, Meenhard Herlyn, Helmut Schaider. Escape form adaptive drug tolerance through OGT and TET1 mediated H3K4me3 remodeling in MAPKi resistant melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5833.

Induction of Telomere Dysfunction Prolongs Disease Control of Therapy-Resistant Melanoma

Purpose: Telomerase promoter mutations are highly prevalent in human tumors including melanoma. A subset of patients with metastatic melanoma often fail multiple therapies, and there is an unmet and urgent need to prolong disease control for those patients.Experimental Design: Numerous preclinical therapy-resistant models of human and mouse melanoma were used to test the efficacy of a telomerase-directed nucleoside, 6-thio-2'-deoxyguanosine (6-thio-dG). Integrated transcriptomics and proteomics approaches were used to identify genes and proteins that were significantly downregulated by 6-thio-dG.Results: We demonstrated the superior efficacy of 6-thio-dG both in vitro and in vivo that results in telomere dysfunction, leading to apoptosis and cell death in various preclinical models of therapy-resistant melanoma cells. 6-thio-dG concomitantly induces telomere dysfunction and inhibits the expression level of AXL.Conclusions: In summary, this study shows that indirectly targeting aberrant telomerase in melanoma cells with 6-thio-dG is a viable therapeutic approach in prolonging disease control and overcoming therapy resistance. Clin Cancer Res; 24(19); 4771-84. ©2018 AACR See related commentary by Teh and Aplin, p. 4629.

A slow-cycling subpopulation of melanoma cells with highly invasive properties

Melanoma is a heterogeneous tumor with different subpopulations showing different proliferation rates. Slow-cycling cells were previously identified in melanoma, but not fully biologically characterized. Using the label-retention method, we identified a subpopulation of slow-cycling cells, defined as label-retaining cells (LRC), with strong invasive properties. We demonstrate through live imaging that LRC are leaving the primary tumor mass at a very early stage and disseminate to peripheral organs. Through global proteome analyses, we identified the secreted protein SerpinE2/protease nexin-1 as causative for the highly invasive potential of LRC in melanomas.

Tumor-associated B-cells induce tumor heterogeneity and therapy resistance

In melanoma, therapies with inhibitors to oncogenic BRAFV600E are highly effective but responses are often short-lived due to the emergence of drug-resistant tumor subpopulations. We describe here a mechanism of acquired drug resistance through the tumor microenvironment, which is mediated by human tumor-associated B cells. Human melanoma cells constitutively produce the growth factor FGF-2, which activates tumor-infiltrating B cells to produce the growth factor IGF-1. B-cell-derived IGF-1 is critical for resistance of melanomas to BRAF and MEK inhibitors due to emergence of heterogeneous subpopulations and activation of FGFR-3. Consistently, resistance of melanomas to BRAF and/or MEK inhibitors is associated with increased CD20 and IGF-1 transcript levels in tumors and IGF-1 expression in tumor-associated B cells. Furthermore, first clinical data from a pilot trial in therapy-resistant metastatic melanoma patients show anti-tumor activity through B-cell depletion by anti-CD20 antibody. Our findings establish a mechanism of acquired therapy resistance through tumor-associated B cells with important clinical implications.Resistance to BRAFV600E inhibitors often occurs in melanoma patients. Here, the authors describe a potential mechanism of acquired drug resistance mediated by tumor-associated B cells-derived IGF-1.

Abstract 650: B lymphocytes promote upregulation of an IL-1-NfkB dependent signaling and increase invasiveness of triple negative breast cancer

Triple negative breast cancer (TNBC) is an aggressive form of breast cancer that progresses quickly from a non-invasive carcinoma in situ to an invasive state. Chronic inflammation associated to humoral immune responses has been found to promote aggressiveness in a number of solid tumor types. In breast cancer, B lymphocytes are associated with microinvasive disease and correlate with expression of inflammatory genes. The purpose of our work is to study the impact of B lymphocytes on the tumor microenvironment and increased invasiveness of TNBC cells. Through real-time PCR, we demonstrate that co-culture of B lymphocytes and TNBC cells leads to increased mRNA levels of IL1β and its downstream target interleukin 8 (IL8) in both B lymphocytes and in TNBC cells. Western Blot analysis shows that co-culture also leads to increased phosphorylation of p65, indicating IL-1 β activation of NFκB signaling. Additionally, co-culture of B lymphocytes with TNBC cells leads to increased expression of matrix metalloproteinases (MMPs) and cellular invasion through a matrigel invasion chamber. Gelatin zymography reveals increased functional MMP2 and MMP9 in tumor cell supernatant following co-culture with B lymphocytes. To complement our in vitro studies, we examined the presence of CD20+ B cells and expression of inflammatory cytokines IL-1β and IL-8 by immunohistochemistry in serial sections of tissue microarrays from patients with estrogen receptor (ER) positive and negative ductal carcinoma in situ (DCIS) and invasive carcinoma. Large areas of densely populated B cells were observed in ER-DCIS and in invasive TNBC compared to ER+ DCIS. Furthermore, in ER- DCIS and TNBC, both B lymphocytes and tumor cells are found to express IL1β whereas IL8 is found more specifically to be expressed by tumor cells. Our findings support the hypothesis that B lymphocytes promote a chronic inflammatory environment leading to increased invasion of TNBC cells.

Citation Format: Nicole Flynn, Rajasekharan Somasundaram, Jennifer Sims-Mourtada. B lymphocytes promote upregulation of an IL-1-NfkB dependent signaling and increase invasiveness of triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 650. doi:10.1158/1538-7445.AM2017-650

Immune checkpoint inhibitor responses in humanized mouse melanoma models using patient-derived xenografts

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Background: Melanoma patients develop resistance to both chemo- and targeted-therapy drugs. Promising pre-clinical and clinical results with immune checkpoint inhibitors using antibodies directed against CTLA-4 and PD-1 have re-energized the field of immune-based therapies in melanoma. However, only a third of melanoma patients respond to immune checkpoint blockade. Currently available mouse xenograft and transgenic mouse melanoma models have a number of short comings and are unable to address the basis of drug resistance and immune non-responsiveness that are frequently observed in melanoma patients. Thus there is an urgent need to establish an in vivo model with a human immune microenvironment that can address issues of therapy resistance. Methods: Our laboratory has developed a humanized mouse melanoma model using patient-derived xenografts (PDX). Results: Immunodeficient NSG mice were reconstituted with human CD34+ cells and after 7-9 weeks, mature human CD45+ cells were observed in circulating blood. Humanized mice were then challenged with HLA-matched melanoma PDX and the functional ability of human immune cells to restrict tumor growth was monitored. Delayed tumor growth was observed in humanized mice indicating in vivo sensitization of human immune cells to melanoma. This was confirmed by in vitro demonstration of human lymphocytes from tumor-bearing mice showing enhanced cytokine expression after stimulation with melanoma antigen peptides. Further, cytotoxic T-cells derived from melanoma peptide stimulation were able to functionally lyse tumor cells in vitro. In preliminary therapy studies, a majority of tumor-bearing humanized mice treated with anti-PD-1 antibody showed restricted tumor growth and a combination of BRAF inhibitor and anti-PD1 antibody treatment showed prolonged survival. Conclusions: Our results suggest that humanized mouse melanoma model can be explored further to understand the causes of therapy resistance and immune non-responsiveness.

[Reasons for Emergency Department Visits: Results of a Patient Survey]

OBJECTIVES

The number of patients visiting emergency departments (ED) is steadily increasing. The cause for this rise in Germany is unclear and less examined. This study aimed to assess the reasons of walk-in patients to visit EDs by using a direct survey.

METHODS

During a period of 4 weeks, 2 010 walk-in patients were anonymously surveyed in 2 major Berlin hospitals using a standardized questionnaire. Descriptive statistics were used for data analysis.

RESULTS

More than 90% of patients assessed themselves as an emergency and three-quarters of patients reported pain. The majority of patients (57%) tried to contact statutory health insurance (SHI) office-based physicians in advance and 59% of patients said they would make use of ambulatory emergency facilities if they were available and well established. However, 55% of patients were unaware of the emergency service of the association of SHI physicians.

CONCLUSION

The results indicate that centralized ambulatory emergency facilities should be available 24/7 at hospitals with EDs. Therefore, future planning of emergency services should integrate providers of ambulatory and inpatient sector. International experience suggests that different instruments aiming at better coordination of care, such as integrated call centers, extended ambulatory services and facilities for less urgent cases located in or nearby hospitals with EDs should also be implemented in Germany.

Abstract PR02: Humanized mouse melanoma model using patient-derived xenografts

Melanoma patients develop resistance to both chemo- and targeted-therapy drugs. Promising pre-clinical and clinical results with immune checkpoint inhibitors using antibodies directed against CTLA4 and PD1 have re-energized the field of immune-based therapies in melanoma. However, similar to chemo- or targeted-therapies only subsets of melanoma patients respond to immune checkpoint blockade. Currently available immunodeficient mouse xenograft and transgenic mouse melanoma models have a number of short comings and are unable to address the basis of drug resistance and immune non-responsiveness frequently observed in melanoma patients treated either with chemo- and targeted-therapy drugs or immune checkpoint inhibitors. Thus there is an urgent need to establish a mouse model with an immune microenvironment that can address the above issues encountered in melanoma patients. For this, our laboratory has developed a humanized mouse melanoma model using patient-derived xenograft (PDX). Immunodeficient (NOD/Shi-SCID/IL-2Rgnull [NOG; Taconic]/ NOD.Cg-Prkdcscid IL2rgtm1Wjl/SzJ [NSG; Jackson Laboratory]) mice were reconstituted with human CD34+ cells and after 12 weeks, mature human CD45+ cells are observed in mouse peripheral blood and in the lymphoid organs. Humanized mice with optimum number of mature human CD45+ cells in peripheral blood were challenged with HLA-matched melanoma PDX and the immune response to melanoma associated antigens were monitored. Lymphoid cells derived from humanized mice that are challenged with human leukocyte antigen (HLA) matched melanoma cells in vivo showed enhanced cytokine expression to in vitro stimulation with peptides derived from melanoma antigens. In addition, cytotoxic T-cells were able to functionally lyse tumor cells in vitro, infiltrate and restrict in vivo tumor growth. We are currently refining our model to establish an autologous mouse melanoma model. Our innovative humanized mouse melanoma model will enable one to understand the causes of therapy resistance and immune non-responsiveness in patients.

This abstract is also being presented as Poster B33.

Citation Format: Clemens Krepler, Michela Perego, Mizuho Kalabis, Marilda Beqiri, Denitsa Hristova, Min Xiao, Nicholas J. Petrelli, Rajasekharan Somasundaram, Meenhard Herlyn. Humanized mouse melanoma model using patient-derived xenografts. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr PR02.

Nivolumab in combination with ipilimumab for the treatment of melanoma

Melanoma patients develop resistance to most therapies, including chemo- and targeted-therapy drugs. Single-agent therapies are ineffective due to the heterogeneous nature of tumors comprising several subpopulations. Treatment of melanoma with immune-based therapies such as anti-cytotoxic T-lymphocyte activation-4 and anti-programmed death-1 antibodies has shown modest but long-lasting responses. Unfortunately, only subsets of melanoma patients respond to antibody-based therapies. Heterogeneity in lymphocyte infiltration and low frequency of anti-melanoma-reactive T-cells in tumor lesions are partly responsible for a lack of response to antibody-based therapies. Both antibodies have same biological function but they bind to different ligands at various phases of T-cell activity. Thus, combination therapy of antibodies has shown superior response rates than single-agent therapy. However, toxicity is a cause of concern in these therapies. Future identification of therapy-response biomarkers, mobilization of tumor-reactive T-cell infiltration using cancer vaccines, or non-specific targeted-therapy drugs will minimize toxicity levels and provide long-term remissions in melanoma patients.

[Patients with Acute, Non-Traumatic Abdominal Pain in German Emergency Departments: A Prospective Monocentric Observation Study]

Background: Up to 11 % of patients in an Emergency Department (ED) present with non-traumatic acute abdominal pain. Based on this presenting symptom, this study aimed to analyse how residents (surgery, internal medicine, anaesthesiology and other fields) working in an ED during their second and third year of education treat these patients. Material and Methods: We performed a prospective, monocentric observation study in an ED in accordance with the STROBE recommendations, following the recommendations from the Ethics Committee of the University of Ulm (application no. 335/12) and the Declaration of Helsinki. The hospital's data protection officer approved the study. During a 12-month period (Dec. 2012 to Dec. 2013), a random sample of patients with non-traumatic abdominal pain was obtained in the ED of a major German acute care hospital by an independent observer, who was not part of the ED team. In addition to demographic data, the study focused on analysing processes and patient care (including medical history taking and physical examinations). In addition, subgroups were defined (clinical background of the treating physician, severity pursuant to the Manchester Triage Score [MTS]). Results: 143 patients met the inclusion criteria. The clinical background of the physician had no influence on the reviewed processes such as medical history taking, initial examinations, the request of consultative examinations or diagnostic procedures. Patients triaged as "urgent" were treated significantly earlier than patients triaged as "non-urgent" (time to first physician contact 26 ± 24 vs. 46 ± 34 min, p < 0.001). However, the overall time spent in the ED was equal (210 ± 79 vs. 220 ± 114 min, p = 0.555). Yet the initially estimated urgency was correlated with the need for hospitalisation (share: 57 %). Conclusion: The overall compliance with standards of care was high. The clinical background (surgery, internal medicine, anaesthesiology, other fields) of the physician in charge of initial treatment had no influence on the reviewed processes.

The role of tumor microenvironment in melanoma therapy resistance

Melanoma patients develop resistance to both chemotherapy and targeted-therapy drugs. Promising preclinical and clinical results with immune checkpoint inhibitors using antibodies directed against cytotoxic T-lymphocyte-associated protein 4 and programmed cell death protein 1 have re-energized the field of immune-based therapies in melanoma. However, similar to chemotherapy or targeted therapies, immune checkpoint blockade responds in only subsets of melanoma patients. A number of factors, including gene mutations, altered cell-signaling pathways and tumor heterogeneity can contribute to therapy resistance. Recent studies have highlighted the role of inflammatory tumor microenvironment on therapy resistance of cancer cells. Cancer cells either alone or in conjunction with the tumor stroma can contribute to an inflammatory microenvironment. Multimodal approaches of targeting the tumor microenvironment, in addition to malignant cells, may be necessary for better therapy responses.

Heterogeneity in Melanoma

Melanoma is among the most aggressive and therapy-resistant human cancers. While great strides in therapy have generated enthusiasm, many challenges remain. Heterogeneity is the most pressing issue for all types of therapy. This chapter summarizes the clinical classification of melanoma, of which the research community now adds additional layers of classifications for better diagnosis and prediction of therapy response. As the search for new biomarkers increases, we expect that biomarker analyses will be essential for all clinical trials to better select patient populations for optimal therapy. While individualized therapy that is based on extensive biomarker analyses is an option, we expect in the future genetic and biologic biomarkers will allow grouping of melanomas in such a way that we can predict therapy outcome. At this time, tumor heterogeneity continues to be the major challenge leading inevitably to relapse. To address heterogeneity therapeutically, we need to develop complex therapies that eliminate the bulk of the tumor and, at the same time, the critical subpopulations.

Abstract 420: The role of tumor microenvironment in therapy resistance and melanoma progression

Melanoma patients develop resistance to both chemo- and targeted-therapy drugs. Promising pre-clinical and clinical results with immune checkpoint inhibitors using antibodies directed against CTLA4 and PD1 have re-energized the field of immune-based therapies in melanoma. However, similar to chemo- or targeted-therapies only subsets of melanoma patients respond to immune checkpoint blockade. Studies from our laboratory have indicated that the tumor microenvironment (TME) might play a role in the emergence of therapy resistant tumor subpopulations. The TME actively recruits a number of immune and non-immune cells. A recent study describes immune cells as an important component of TME. About 33% of the infiltrating immune cells are of ‘B-cell’ lineage and yet, there is very little information on the role of these cells in melanoma cell biology. Our results suggest that B cells isolated from the tumor tissues of melanoma patients show higher inflammatory cytokine expressions (IGF-1, IL-1, PDGF and VEGF) when compared to circulating B cells. Presence of inflammatory cytokines in the TME results in the induction of heterogeneous melanoma subpopulation, down modulation of melanoma associated antigens (MAA), and thus, therapy resistance of melanoma. Here, we report a novel mechanism of acquired drug resistance in melanoma induced by tumor-associated B cells involving FGF-2/FGFR-3 and IGF-1 signaling. B-cell derived IGF-1 modulates the emergence of therapy resistant heterogeneous melanoma subpopulations. Neutralization of IGF-1 reverses the induction of heterogeneous melanoma subpopulations. We are currently evaluating the mechanism of down modulation of MAA in presence of inflammatory cytokines. Our studies confirm the important role of the TME in the induction of therapy resistant tumor subpopulations and offer a new combination treatment approach of targeting melanoma (Supported by AMRF and NIH grant CA114046).

Citation Format: Rajasekharan Somasundaram, Gao Zhang, Stephan N. Wagner, Mizuho Fukunaga-Kalabis1, Meenhard Herlyn. The role of tumor microenvironment in therapy resistance and melanoma progression. [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 420. doi:10.1158/1538-7445.AM2015-420

Abstract 2684: An early innate stress response precedes acquired drug resistance in melanoma

Acquired drug resistance constitutes a major challenge for effective cancer therapies. The dynamics of early drug resistance leading to permanent resistance are poorly understood. Melanoma cell lines were exposed to molecular targeted inhibitors like BRAF or MEK inhibitors or chemotherapy at sublethal drug concentrations for over 90 days. Alternatively melanoma cells were exposed to hypoxic conditions or low glucose media. Cells surviving drug exposure, hypoxia or nutrient starvation were monitored for the expression of CD271, ALDH activity, differentiation markers, ABCB5, chromatin remodeling, histone demethylases and markers for angiogenesis to characterize cells exposed for a minimum of 12 days. Further gene expression analyses, RPPA analyses and in vivo tumorigenicity were performed in these cells. Drug exposure, hypoxia or nutrient starvation leads to an early innate cell response in melanoma cells resulting in multi-drug resistance, termed induced drug tolerant cells (IDTC). Transition into the IDTC state seems to be an inherent stress reaction for survival towards unfavorable environmental conditions or drug exposure independent of any subpopulation or cancer stem cell. The response comprises chromatin remodeling, activation of signaling cascades, and markers proposed to be stem cell markers with higher angiogenic potential and tumorigenicity. These changes are characterized by a common increase in CD271 expression concomitantly with loss of differentiation markers such as melan-A and tyrosinase, enhanced ALDH activity and upregulation of histone demethylases. Accordingly, IDTCs show a loss of H3K4me3, H3K27me3 and gain of H3K9me3 suggesting activation and repression of differential genes. Drug holidays at the IDTC state allow for reversion into parental cells re-sensitizing them to the drug they were primarily exposed to. However, upon continuous drug exposure IDTCs eventually transform into permanent and irreversible drug resistant cells. Knockdown of CD271 or KDM5B decreases transition into the IDTC state substantially but does not prevent it. Our results suggest a phenotypic shift of parental cells to the induced drug tolerant cell (IDTC) state irrespective of a given subpopulation thus not representing cancer stem cells. Targeting IDTCs would be crucial for sustainable disease management and prevention of acquired drug resistance.

Citation Format: Dinoop Ravindran Menon, Suman Das, Clemens Krepler, Adina Vultur, Gao Zhang, Nikolas Haass, Peter H. Soyer, Brian Gabrielli, Rajasekharan Somasundaram, Gerald Hoefler, Meenhard Herlyn, Helmut Schaider. An early innate stress response precedes acquired drug resistance in melanoma. [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 2684. doi:10.1158/1538-7445.AM2015-2684

Comparison of the source of introduction to cariogenic food substance and caries prevalence in children

INTRODUCTION

Dental caries being a multi-factorial disease depends on lot of factors. Since awareness and exposure seems to have increased, in the present scenario it is difficult to assume that one particular source would increase the occurrence of dental caries. Children are exposed to different media sources and spend most of their free time watching them. They are attracted by messages of advertisers' and susceptible to stylish advertisements of foods often harmful to oral and general health.

AIM

To compare the effects of three different sources of introduction to cariogenic food substance among school children and their role in caries prevalence.

MATERIALS AND METHODS

A total of 300 school children were selected for the study and a questionnaire was prepared keeping in mind the various sources introducing cariogenic foods to children namely television advertisement, magazines/news paper, posters/banners. Following which oral examination will be done to determine the number of carious lesions in the subjects. The data will be acquired, computed and statistically analysed to compare the correlation between these sources and caries prevalence.

RESULTS

Children who watched television advertisements and asked for food items and soft drinks were found to have more caries and DMFT/dmft index.

CONCLUSION

A total ban on advertisements would not be practically possible. A more realistic approach would be to limit the number of advertisements that feature potentially cariogenic and unhealthy food products, and also ensure that they ideally carry statutory warnings.

Antimelanoma CTL recognizes peptides derived from an ORF transcribed from the antisense strand of the 3' untranslated region of TRIT1

Noncoding regions of the genome play an important role in tumorigenesis of cancer. Using expression cloning, we have identified a cytotoxic T lymphocyte (CTL)-defined antigen that recognizes a protein sequence derived from an open reading frame transcribed from the reverse strand in the 3' untranslated region of tRNA isopentenyltransferase 1 (TRIT1). A peptide derived from this open reading frame (ORF) sequence and predicted to bind to HLA-B57, sensitized HLA-B57(+) tumor cells to lysis by CTL793. The peptide also induced a CTL response in peripheral blood mononuclear cells (PBMC) of patient 793 and in two other melanoma patients. The CTL lysed peptide-pulsed HLA-B57(+) target cells and melanoma cells with endogenous antigen expression. The recognition of this antigen is not limited to HLA-B57-restricted CTLs. An HLA-A2 peptide derived from the ORF was able to induce CTLs in PBMC of 2 HLA-A2(+) patients. This study describes for the first time a CTL-defined melanoma antigen that is derived from an ORF on the reverse strand of the putative tumor suppressor gene TRIT1. This antigen has potential use as a vaccine or its ability to induce CTLs in vitro could be used as a predictive biomarker.

A stress-induced early innate response causes multidrug tolerance in melanoma

Acquired drug resistance constitutes a major challenge for effective cancer therapies with melanoma being no exception. The dynamics leading to permanent resistance are poorly understood but are important to design better treatments. Here we show that drug exposure, hypoxia or nutrient starvation leads to an early innate cell response in melanoma cells resulting in multidrug resistance, termed induced drug-tolerant cells (IDTCs). Transition into the IDTC state seems to be an inherent stress reaction for survival toward unfavorable environmental conditions or drug exposure. The response comprises chromatin remodeling, activation of signaling cascades and markers implicated in cancer stemness with higher angiogenic potential and tumorigenicity. These changes are characterized by a common increase in CD271 expression concomitantly with loss of differentiation markers such as melan-A and tyrosinase, enhanced aldehyde dehydrogenase (ALDH) activity and upregulation of histone demethylases. Accordingly, IDTCs show a loss of H3K4me3, H3K27me3 and gain of H3K9me3 suggesting activation and repression of differential genes. Drug holidays at the IDTC state allow for reversion into parental cells re-sensitizing them to the drug they were primarily exposed to. However, upon continuous drug exposure IDTCs eventually transform into permanent and irreversible drug-resistant cells. Knockdown of CD271 or KDM5B decreases transition into the IDTC state substantially but does not prevent it. Targeting IDTCs would be crucial for sustainable disease management and prevention of acquired drug resistance.

Hepatitis C virus infection and kidney transplantation in 2014: what's new?

Chronic hepatitis C virus (HCV) infection remains an important health problem, which is associated with deleterious consequences in kidney transplant recipients. Besides hepatic complications, several extrahepatic complications contribute to reduced patient and allograft survival in HCV-infected kidney recipients. However, HCV infection should not be considered as a contraindication for kidney transplantation because patient survival is better with transplantation than on dialysis. Treatment of HCV infection is currently interferon-alpha (IFN-α) based, which has been associated with higher renal allograft rejection rates. Therefore, antiviral treatment before transplantation is preferable. As in the nontransplant setting, IFN-free treatment regimens, because of their greater efficacy and reduced toxicity, currently represent promising and attractive therapeutic options after kidney transplantation as well. However, clinical trials will be required to closely evaluate these regimens in kidney recipients. There is also a need for prospective controlled studies to determine the optimal immunosuppressive regimens after transplantation in HCV-infected recipients. Combined kidney and liver transplantation is required in patients with advanced liver cirrhosis. However, in patients with cleared HCV infection and early cirrhosis without portal hypertension, kidney transplantation alone may be considered. There is some agreement about the use of HCV-positive donors in HCV-infected recipients, although data regarding posttransplant survival rates are controversial.

Indomethacin to the rescue of TRAIL-resistant melanomas

Patients with melanomas develop resistance to both conventional- and targeted-therapy drugs. Promising clinical responses with immune checkpoint reagents have resulted in renewed interest in the use of biological therapies, although only subsets of individuals are known to respond to these reagents. Tse et al. now report on the use of indomethacin, an anti-inflammatory drug, to sensitize therapy-resistant melanoma cells.

Isolation of melanoma cell subpopulations using negative selection

Melanomas are phenotypically and functionally heterogeneous tumors comprising of distinct subpopulations that drive disease progression and are responsible for resistance to therapy. Identification and characterization of such subpopulations are highly important to develop novel targeted therapies. However, this can be a challenging task as there is a lack of clearly defined markers to distinguish the melanoma subpopulations from a general tumor cell population. Also, there is a lack of optimal isolation methods and functional assays that can fully recapitulate their phenotype. Here we describe a method for isolating tumor cells from fresh human tumor tissue specimens using an antibody coupled magnetic bead sorting technique that is well established in our laboratory. Thus, melanoma cells are enriched by negative cell sorting and elimination of non-tumor cell population such as erythrocytes, leukocytes, and endothelial cells. Enriched unmodified tumor cells can be further used for phenotypic and functional characterization of melanoma subpopulations.

SECTM1 produced by tumor cells attracts human monocytes via CD7-mediated activation of the PI3K pathway

Tumor-associated macrophages (TAMs) play essential roles in tumor progression and metastasis. Tumor cells recruit myeloid progenitors and monocytes to the tumor site, where they differentiate into TAMs; however, this process is not well studied in humans. Here we show that human CD7, a T cell and NK cell receptor, is highly expressed by monocytes and macrophages. Expression of CD7 decreases in M-CSF differentiated macrophages and in Melanoma-conditioned Medium Induced Macrophages (MCMI/Mϕ) in comparison to monocytes. A ligand for CD7, SECTM1 (Secreted and transmembrane protein 1), is highly expressed in many tumors, including melanoma cells. We show that SECTM1 binds to CD7 and significantly increases monocyte migration by activation of the PI3K pathway. In human melanoma tissues, tumor-infiltrating macrophages expressing CD7 are present. These melanomas, with CD7-positive inflammatory cell infiltrations, frequently highly express SECTM1, including an N-terminal, soluble form, which can be detected in the sera of metastatic melanoma patients but not in normal sera. Taken together, our data demonstrate that CD7 is present on monocytes and tumor macrophages, and that its ligand, SECTM1, is frequently expressed in corresponding melanoma tissues, possibly acting as a chemoattractant for monocytes to modulate the melanoma microenvironment.

Comparative secretome analysis of epithelial and mesenchymal subpopulations of head and neck squamous cell carcinoma identifies S100A4 as a potential therapeutic target

Epithelial-mesenchymal transition (EMT) is a key contributor in tumor progression and metastasis. EMT produces cellular heterogeneity within head and neck squamous cell carcinomas (HNSCC) by creating a phenotypically distinct mesenchymal subpopulation that is resistant to conventional therapies. In this study, we systematically characterized differences in the secretomes of E-cadherin high epithelial-like and E-cadherin low mesenchymal-like subpopulations using unbiased and targeted proteomics. A total 1765 proteins showed significant changes with 177 elevated in the epithelial subpopulation and 173 elevated in the mesenchymal cells. Key nodes in affected networks included NFκB, Akt, and ERK, and most implicated cellular components involved various aspects of the extracellular matrix. In particular, large changes were observed in multiple collagens with most affected collagens at much higher abundance levels in the mesenchymal subpopulation. These cells also exhibited a secretome profile resembling that of cancer-associated fibroblastic cells (CAF). S100A4, a commonly used marker for cancer-associated fibroblastic cells, was elevated more than 20-fold in the mesenchymal cells and this increase was further verified at the transcriptome level. S100A4 is a known mediator of EMT, leading to metastasis and EMT has been proposed as a potential source of cancer-associated fibroblastic cells in solid tumors. S100A4 knockdown by small interfering RNA led to decreased expression, secretion and activity of matrix metalloproteinase 2, as verified by quantitative PCR, multiple reaction monitoring and zymography analyses, and reduced invasion in collagen-embedded spheroids. Further confirmation in three-dimensional organotypic reconstructs showed less invasion and advanced differentiation in the S100A4 RNA interference samples. Orthotopic metastasis model, developed to validate the findings in vivo, demonstrated a decrease in spontaneous metastasis and augmented differentiation in the primary tumor in siS100A4 xenografts. These results demonstrate the value of secretome profiling to evaluate phenotypic conversion and identify potential novel therapeutic targets such as S100A4.