Transcriptomic and Proteomic Analysis of Tumor Markers in Tissue and Blood from Patients with Lung Cancer

Abstract: Despite recent treatment advancements, the survival outcome remains poor for the majority of patients with non-small cell lung cancer (NSCLC). The aim of this thesis was to evaluate protein expression to predict prognosis and identify biomarkers that can be used as targets for immunotherapy or for early detection of NSCLC.In Paper I an optimized immunohistochemistry (IHC)-based prognostic model was developed for NSCLC. The prognostic performance of the model was compared to the clinicopathological parameters that are used in the clinical setting to predict outcome. The protein model failed to outperform clinicopathological parameters in predicting survival outcome questioning the potential of IHC-based assessment of prognostic markers in NSCLC.In Paper II the human testis-specific proteome was profiled using RNA-sequencing (RNA-seq) data from testis and 26 other organs. More than 1000 genes demonstrated a testis-enriched expression pattern which makes testis the tissue with the most tissue-specific genes. The majority of the testis-enriched genes were previously poorly described and were further profiled by IHC. This analysis provides a starting point to increase the molecular understanding of testicular biology.In Paper III the profiling of cancer-testis antigens (CTAs) was performed in NSCLC by using RNA-seq data from 32 normal organs and NSCLC. Ninety genes showed CTA expression profiles. The transcriptomic data were validated by IHC for several CTAs. The comprehensive analysis of CTAs can guide biomarker studies or help to identify targets for immunotherapeutic strategies.In Paper IV the reactivity of CTAs was evaluated by measuring the abundance of autoantibodies in plasma from patients with NSCLC and benign lung diseases. Twenty-nine CTAs demonstrated exclusive reactivity in NSCLC and six of them were reactive in an independent NSCLC cohort. These findings suggest that some CTAs are immunogenic and could be utilized in immunotherapy.In Paper V an immunoassay was used on lung adenocarcinoma plasma samples and samples from benign lung diseases. The plasma levels of 92 cancer related proteins were used to build a model that discriminated lung adenocarcinoma from benign controls with a sensitivity of 93% and a specificity of 64%. The results indicate that this assay is promising for the early detection of NSCLC.In summary, this thesis presents an integrative analysis of lung cancer tissue and blood samples to characterize NSCLC on the transcriptomic and proteomic level and to identify cancer specific proteins.