Arno Amann

Development of an Innovative 3D Cell Culture System to Study Tumour - Stroma Interactions in Non-Small Cell Lung Cancer Cells

Introduction We describe a novel 3D co-culture model using non-small cell lung cancer (NSCLC) cell lines in combination with lung fibroblasts. This model allows the investigation of tumour-stroma interactions and addresses the importance of having a more in vivo like cell culture model. Methods Automation-compatible multi-well hanging drop microtiter plates were used for the production of 3D mono- and co-cultures. In these hanging drops the two NSCLC cell lines A549 and Colo699 were cultivated either alone or co-cultured with lung fibroblasts. The viability of tumour spheroids was confirmed after five and ten days by using Annexin V/Propidium Iodide staining for flow-cytometry. Tumour fibroblast spheroid formation was characterized by scanning electron microscope (SEM), semi-thin sections, fluorescence microscope and immunohistochemistry (IHC). In addition to conventional histology, protein expression of E-Cadherin, vimentin, Ki67, fibronectin, cytokeratin 7 and α-smooth muscle actin (α-SMA) was investigated by IHC. Results Lower viability was observed in A549 monocultures compared to co-cultures, whereas Colo699 monocultures showed better viability compared to co-cultures. Ki67 expression varied significantly between mono- and co-cultures in both tumour cell lines. An increase of vimentin and decreased E-Cadherin expression could be detected during the course of the cultivation suggesting a transition to a more mesenchymal phenotype. Furthermore, the fibroblast cell line showed an expression of α-SMA only in co-culture with the cancer cell line A549, thereby indicating a mesenchymal to mesenchymal shift to an even more myofibroblast phenotype. Conclusion We demonstrate that our method is a promising tool for the generation of tumour spheroid co-cultures. Furthermore, these spheroids allow the investigation of tumour-stroma interactions and a better reflection of in vivo conditions of cancer cells in their microenvironment. Our method holds potential to contribute to the development of anti-cancer agents and support the search for biomarkers.

Neoadjuvant chemo-immunotherapy modifies CD4(+)CD25(+) regulatory T cells (Treg) in non-small cell lung cancer (NSCLC) patients.

BACKGROUND Regulatory T cells (Treg) are critical for cancer immune evasion; whereas natural killer (NK) cells are central for effective anti-tumor immunity including antibody-induced cellular cytotoxicity (ADCC). The predictive role of Treg levels for clinical response to chemo-immunotherapy in non-small cell lung cancer (NSCLC) as well as therapy-induced Treg changes remain to be defined. PATIENTS AND METHODS The impact of Treg on NK-mediated cetuximab-dependent cellular cytoxicity was tested in vitro. Frequency and functional activity of Treg was analyzed in 31 NSCLC stage IB-IIIA patients treated by neoadjuvant Cetuximab/Docetaxel/Cisplatin prior to surgery. Data were correlated with clinical outcome variables and Treg tumor infiltration. RESULTS Treg potently inhibit NK-mediated and cetuximab-induced ADCC in vitro. In addition, a significant correlation between Treg reduction and clinical response was seen. However, the grade of tumor infiltrating Treg in resected tumors did not correlate with peripheral Treg levels. Moreover, Treg levels at diagnosis did not predict clinical response to chemo-immunotherapy. CONCLUSIONS The drop of Treg levels during neoadjuvant chemo-immunotherapy in NSCLC patients significantly correlates with clinical response. However, Treg at diagnosis are not linked to inferior clinical response to chemo-immunotherapy in NSCLC in vivo even though Treg efficiently inhibit ADCC in vitro.

Implementing liquid biopsies into clinical decision making for cancer immunotherapy

During the last decade, novel immunotherapeutic strategies, in particular antibodies directed against immune checkpoint inhibitors, have revolutionized the treatment of different malignancies leading to an improved survival of patients. Identification of immune-related biomarkers for diagnosis, prognosis, monitoring of immune responses and selection of patients for specific cancer immunotherapies is urgently required and therefore areas of intensive research. Easily accessible samples in particular liquid biopsies (body fluids), such as blood, saliva or urine, are preferred for serial tumor biopsies. Although monitoring of immune and tumor responses prior, during and post immunotherapy has led to significant advances of patients’ outcome, valid and stable prognostic biomarkers are still missing. This might be due to the limited capacity of the technologies employed, reproducibility of results as well as assay stability and validation of results. Therefore solid approaches to assess immune regulation and modulation as well as to follow up the nature of the tumor in liquid biopsies are urgently required to discover valuable and relevant biomarkers including sample preparation, timing of the collection and the type of liquid samples. This article summarizes our knowledge of the well-known liquid material in a new context as liquid biopsy and focuses on collection and assay requirements for the analysis and the technical developments that allow the implementation of different high-throughput assays to detect alterations at the genetic and immunologic level, which could be used for monitoring treatment efficiency, acquired therapy resistance mechanisms and the prognostic value of the liquid biopsies.

Characterization of DLK1(PREF1)+/CD34+ cells in vascular stroma of human white adipose tissue

Sorting of native (unpermeabilized) SVF-cells from human subcutaneous (s)WAT for cell surface staining (cs) of DLK1 and CD34 identified three main populations: ~10% stained cs-DLK1+/cs-CD34-, ~20% cs-DLK1+/cs-CD34+dim and ~45% cs-DLK1-/cs-CD34+. FACS analysis after permeabilization showed that all these cells stained positive for intracellular DLK1, while CD34 was undetectable in cs-DLK1+/cs-CD34- cells. Permeabilized cs-DLK1-/cs-CD34+ cells were positive for the pericyte marker α-SMA and the mesenchymal markers CD90 and CD105, albeit CD105 staining was dim (cs-DLK1-/cs-CD34+/CD90+/CD105+dim/α-SMA+/CD45-/CD31-). Only these cells showed proliferative and adipogenic capacity. Cs-DLK1+/cs-CD34- and cs-DLK1+/cs-CD34+dim cells were also α-SMA+ but expressed CD31, had a mixed hematopoietic and mesenchymal phenotype, and could neither proliferate nor differentiate into adipocytes. Histological analysis of sWAT detected DLK1+/CD34+ and DLK1+/CD90+ cells mainly in the outer ring of vessel-associated stroma and at capillaries. DLK1+/α-SMA+ cells were localized in the CD34- perivascular ring and in adventitial vascular stroma. All these DLK1+ cells possess a spindle-shaped morphology with extremely long processes. DLK1+/CD34+ cells were also detected in vessel endothelium. Additionally, we show that sWAT contains significantly more DLK1+ cells than visceral (v)WAT. We conclude that sWAT has more DKL1+ cells than vWAT and contains different DLK1/CD34 populations, and only cs-DLK1-/cs-CD34+/CD90+/CD105+dim/α-SMA+/CD45-/CD31- cells in the adventitial vascular stroma exhibit proliferative and adipogenic capacity.

Development of a 3D angiogenesis model to study tumour – endothelial cell interactions and the effects of anti-angiogenic drugs

The tumour microenvironment and tumour angiogenesis play a critical role in the development and therapy of many cancers, but in vitro models reflecting these circumstances are rare. In this study, we describe the development of a novel tri-culture model, using non-small cell lung cancer (NSCLC) cell lines (A549 and Colo699) in combination with a fibroblast cell line (SV 80) and two different endothelial cell lines in a hanging drop technology. Endothelial cells aggregated either in small colonies in Colo699 containing microtissues or in tube like structures mainly in the stromal compartment of microtissues containing A549. An up-regulation of hypoxia and vimentin, ASMA and a downregulation of E-cadherin were observed in co- and tri-cultures compared to monocultures. Furthermore, a morphological alteration of A549 tumour cells resembling “signet ring cells” was observed in tri-cultures. The secretion of proangiogenic growth factors like vascular endothelial growth factor (VEGF) was measured in supernatants. Inhibition of these proangiogenic factors by using antiangiogenic drugs (bevacizumab and nindetanib) led to a significant decrease in migration of endothelial cells into microtissues. We demonstrate that our method is a promising tool for the generation of multicellular tumour microtissues and reflects in vivo conditions closer than 2D cell culture.

Infiltration of lymphocyte subpopulations into cancer microtissues as a tool for the exploration of immunomodulatory agents and biomarkers

INTRODUCTION The interaction between the immune system and malignant diseases is a proven key target for cancer therapy. We describe an innovative 3D cell culture system comprising both immune and cancer cells to evaluate their interaction and immune cell infiltration to provide an innovative in vitro screening of immunomodulatory agents and biomarkers. METHODS 3D tumor microtissues were cultivated using a hanging drops system. Human non-small-cell lung cancer cell lines were incubated for 7 days to form microtissues. On day 5, peripheral blood mononuclear cells (PBMC) were added with or without interleukin-2 (IL-2) for 24 or 48h. Viability of cancer cells and the infiltrating PBMC subpopulations were investigated by flow cytometry. Aggregation of tumor cells and PBMC and the infiltration of the PBMC into the tumor microtissues were analyzed by immunohistochemistry. Quantification of infiltration was measured by applying the TissueFAXS system. RESULTS Immunohistochemistry revealed PBMC infiltration in all cell lines which increased under IL-2 stimulation. Analysis of infiltrating populations showed both lymphocyte subpopulations and monocytes within the tumor microtissues. In all three co-cultures, CD3+CD8+ and CD3+CD8+CD45R0+CD28+ lymphocytes were increased with IL-2, whereas CD3+CD8+CD45R0-CD28+ PBMCs were decreased with and without IL-2 stimulation. CONCLUSION In summary, we present a novel cell culture system to study the interaction between cancer cells and immune cells in 3-dimensional microtissues. In addition, we report for the first time an in vitro infiltration assay based on 3D microtissues. This model has the potential to provide a tool for ex-vivo drug testing and biomarker screening of immunomodulatory agents.

Increase in antibody-dependent cellular cytotoxicity (ADCC) in a patient with advanced colorectal carcinoma carrying a KRAS mutation under lenalidomide therapy

The failure of EGFR inhibitors in colorectal tumors with KRAS mutations requires the development of alternative treatment strategies for this patient subgroup. Among the hallmarks of cancer the disturbed immunosurveillance and cancer immune evasion have become emerging targets for cancer therapy. Due to their pleiotropic functions immunomodulatory drugs (IMiDs) are interesting agents for combination therapies in solid tumors. However, their possible contribution and a way of monitoring their biological effects have yet to be revealed. In a heavily pretreated patient with advanced colorectal cancer carrying mutations in APC and KRAS genes, we show an early metabolic response and enhanced NK cell activity to monotherapy with lenalidomide. After subsequent lenalidomide/cetuximab combination treatment, the patient had progressive disease. At the same time a reduced performance status, complicated by febrile neutropenia, occurred, as well as a slight increase in metabolic activity. Concordantly NK cell activity dropped back to baseline. Thus, laboratory measurements and metabolic response assessment correlated with clinical conditions. This case report describes the feasibility and potential of a functional assessment of patient derived immune competent cells in combination with functional imaging for the detection of a biological response.

Unmasking low‐abundance peptides from human blood plasma and serum samples by a simple and robust two‐step precipitation/immunoaffinity enrichment method

Proteomic analysis of human plasma and serum for identifying and validating disease‐specific marker proteins and peptides has one major drawback besides its unique advantage as a readily available sample source for diagnostic assays. This disadvantage is represented by the predominance of several high‐ and middle‐abundant proteins, which clearly hamper identification and quantification approaches of potential and validated protein and peptide biomarkers, which are often of very low abundance. During the last decades, a significant number of depletion and enrichment techniques evolved to address these two issues. We present here a cost‐effective and easy‐to‐use strategy for protein depletion comprising a thermal precipitation protocol followed by a two‐step liquid/liquid precipitation as well as using an immunoaffinity chromatography method for the specific enrichment and isolation of the low‐abundance polypeptide N‐terminal pro‐B‐type natriuretic peptide and its precursor proBNP clinically used as biomarkers for the detection of severe human heart failure and related diseases. The applicability of this approach is shown by SDS ‐CGE, SDS‐PAGE, electrochemiluminescence immunoassay and nano‐LC ESI‐MS/MS. Our thermal precipitation protocol followed by a two‐step liquid/liquid precipitation could also serve as a potential depletion technique for the characterization of other low‐abundance peptides and proteins.

The influence of stromal cells and tumor-microenvironment-derived cytokines and chemokines on CD3+CD8+ tumor infiltrating lymphocyte subpopulations

ABSTRACT The tumor microenvironment has been identified as a major mediator of immunological processes in solid tumors. In particular, tumor-associated fibroblasts are known to interact with tumor infiltrating immune cells. We describe the influence of fibroblasts and tumor-microenvironment-derived cytokines on the infiltration capacity of CD3+CD8+ cytotoxic T lymphocyte subpopulations using a multicellular 3D co-culture system. 3D tumor microtissues were cultivated using a hanging drop system. Human A549 and Calu-6 cancer cell lines were incubated alone or together with the human fibroblast cell line SV80 for 10 d to form microtissues. On day 10, peripheral blood mononuclear cells (PBMC) were added with or without cytokine stimulation for 24 h. Infiltrating PBMC subpopulations were investigated by flow cytometry. Aggregation of the microtissues and the infiltration of the PBMCs were analyzed by immunohistochemistry, and endogenous cytokine and chemokine expression was analyzed with a multi-cytokine immunoassay. Secretion of chemokines is increased in microtissues consisting of cancer cells and fibroblasts. PBMC infiltrate the whole spheroid in cancer cell monocultures, whereas in co-cultures of cancer cells and fibroblasts, PBMCs are rather localized at the margin. Activated CD69+ and CD49d+ T lymphocytes show an increased microtissue infiltration in the presence of fibroblasts. We demonstrate that the stromal component of cancer microtissues significantly influences immune cell infiltration. The presence of fibroblasts in cancer microtissues induces a shift of T lymphocyte infiltration toward activated T lymphocytes.

Abstract 326: Differences in RNA expression and chemosensitivity in 2D versus 3D non-small-cell lung cancer cultures

Introduction: Increasing efforts to integrate tumour-stroma interaction and 3-dimensional structures in innovative in-vitro models were made within the last years. We established a 3D co-culture system in non-small-cell lung cancer applicable for drug testing. In this work, we present data on the differences in RNA expression and drug sensitivity in the 2D and 3D culture system. Methods: A549 and Colo699 NSCLC cell lines were both cultivated in a 2D standard cell culture (flasks, PAA, Germany) and a 3D 96 well plate hanging drop system (GravityPlusTM, Insphero, Switzerland) for 5 and 10 days, respectively. 3D microtissues were cultured either in mono- or in co-cultures with the human lung fibroblast cell line SV80. RNA expression profiling via Affymetrix chip analyses was performed with 3 biological replicates per cell line (A549, Colo699 and SV80) in mono- and co-cultures. For this purpose, RNA was isolated by a TriReagent standard protocol. Cytotoxicity was determined for cisplatin and vinorelbine after 24 hours of incubation by ATP measurements of lysed microtissues/cells and modified AnnexinV/Propidium iodide staining for flow cytometry on Colo699 cells. Furthermore, standard flow cytometry cell cycle analyses and microscopic volume measurements were performed to analyse drug induced inhibition of proliferation. Results: RNA expression profiles revealed within the A549 monocultures 892 and the Colo699 monocultures 1,042 regulated genes (≥ two-fold change in expression) for 2D versus 3D cultures, respectively. Between the cell lines A549 and Colo699 only a limited overlap (131 genes) in differentially expressed genes was detected. However, significant differences in gene expression were experienced in co-cultures with SV80. The most frequently altered genes are involved in the regulation of the cell cycle, organelle fission, RNA polymerases, histone methylation, DNA repair, oxidative stress and WNT signalling pathways. To prove the potential in-vivo relevance of these findings, we assessed the chemosensitivity in the Colo699 for 2D and 3D cell cultures. A significant difference in LD50 could be observed for cisplatin between 2D (100μM) and 3D (250μM) cultures in both ATP release measurements and AnnexinV/PI flow cytometry analyses. In cell cycle analyses the maximum M arrest for vinorelbine was achieved with 25μM in 2D, whereas in 3D 100μM of vinorelbine were needed. Cytotoxicity assays did not reveal a significant difference for vinorelbine in 2D versus 3D models. Conclusion: Herein, we demonstrate that cultivation of cell lines either in a 2D or 3D environment lead not only to a difference in RNA expression but also in chemosensitivity. Thereby, these data support the urgent need of more in vivo like cell culture models for analysing drug related modes of action. Citation Format: Gabriele Gamerith, Johannes Rainer, Arno Amann, Stefan Koeck, Edith Lorenz, Heinz Zwierzina, Julia M. Huber. Differences in RNA expression and chemosensitivity in 2D versus 3D non-small-cell lung cancer cultures. [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 326. doi:10.1158/1538-7445.AM2015-326