Development and Characterization of an ex vivo Organotypic Non-Small Cell Lung Cancer Model to Study the Effect of Elevated Oxygen Treatment
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- Master theses 
Lung cancer is a leading cause of cancer-related morbidity and mortality worldwide, and also the cancer-form responsible for most cancer related deaths in Norway. Non-small cell lung cancer (NSCLC) accounts for approximately 80% of the lung cancer cases. Owing to the introduction of targeted therapies and immune checkpoint inhibitors (ICI), the treatment of NSCLC has changed drastically in recent years, in particular due to the remarkable clinical efficacy of ICI observed in a subset of patients. Although a minority of patients show prolonged clinical benefit of these drugs, innate and acquired resistance to ICI limit the clinical benefit and the complex molecular mechanisms mediating resistance is still poorly understood Thus, there are a need for preclinical models which are representative for the heterogeneity of the tumor microenvironment. 3D patient organoids emerge as a unique and robust tool. This in vitro model mimics the biological in vivo characteristics of the primary patient tissue. Since hypoxia is pivotal for cancer growth and progression, we have aimed to study the effect of “the flip of the coin”, namely hyperoxia. Furthermore, to get a better understanding of the complex communication between tumor and the stroma, we combinate the single cell high dimensional analysis technique, imaging mass cytometry with the organoid model. The first two objectives of this thesis were to develop an organoid model from human non-small cell lung cancer resection specimens, and to characterize the histoarchitecture and cellular composition of the organoids compared to the malignant tumors they derive from. Six different tumor resection specimens of various histological subtypes of NSCLC´s was included in the study. Establishment of patient derived organoids were successful for all resection specimens. Comparison between tumor and derived organoid tissues, and between the individual organoids was performed through application of various staining techniques. Additionally, preservation of genetic abbreviations from patient tumor, detected by next generation sequencing (NGS), was elucidated by antibody staining in derived organoids. We were able to confirm that the histological characteristics of different patient derived organoids varied from patient to patient, as expected due to differences in histological subtypes among the tumors. Most importantly, the derived organoids show similar growth characteristics and cellular composition compared to the tumor of origin. Also, the genetic mutations detected in the tumor of origin was shown to be preserved in organoid tissues. Furthermore, the IMC data show variation of protein expression between the adenocarcinoma and squamous cell carcinoma organoids. The cytokeratin, CK7, was shown to be expressed only in the adenocarcinoma derived organoids. The final objective was to explore the effect of normobaric and hyperbaric oxygen treatment on cancer cell proliferation and phenotype, as well as ECM composition. Harvest of organoids in the elevated oxygen treatment groups was less efficient, indicating a suppressive effect of elevated oxygen. Reduced expression of the proliferation marker Ki67 were detected in the normobaric oxygen treatment group compared to control, however the hyperbaric oxygen treatment showed variable results. Thus, these experiments need to be repeated in order to be able to conclude about the efficiency of elevated oxygen therapy, but our results support further exploration of this experimental therapy in the newly established model.