Abstract 1887: Discrimination of aggressive tumor profiles in lung adenocarcinomas using activity based protein profiling by SWATH/DIA-MS mode
Authors: Sajic Tatjana , Arni Stephan , Aebersold Rudolf , Hillinger Sven 
Published: June 2022

(a) Activity-based proteome profiling (ABPP) probes combined with mass spectrometry (MS) is the tool of functional proteomics for the quantification of catalytically active enzymes. Here, we applied a depletion-dependent ABPP for serine hydrolase (SH) profiling in 30-μm thickness cryosections of optimal-cutting-temperature (OCT)-embedded tissue of advanced lung adenocarcinomas (LUAD).

(b) For the proof-of-concept, we profiled SH activities in advanced LUAD disease. We retrospectively analyzed hydrolase activity differences with prognostic values related to aggressive phenotype based on clinical data collected over the course of disease progression. Interestingly, detection of proteins correlating by active-enzyme capture uncover their functional links with the metabolic SHs related to the enhanced palmitoylation-depalmitoylation cycle of lipoproteins in aggressive LUAD. In contrast, the standard DDA-MS analysis of on-bead-depleted enzymes detected 95 SH’s of which less than 60 enzymes were quantified based on spectral counting.

(c) We found enhanced activities of dozen SHs in all LUAD tumors. Remarkably, the activity of 11 hydrolases emphasized by IAH1, ABHD12, LYPLA2 and MST1 discriminate aggressive tumors at the time of diagnosis. Functional analysis leveraging enzymes and associated co-depleted proteins revealed catabolic processing of lipoproteins and enrichment of enzymes displaying increased de-palmitoylase activities. This is interesting because multiple isoforms of RAS protein (K-RAS, H-RAS and N-RAS), the most frequently mutated oncogene in human cancers including LUAD (i.e. 30% of LUADs contain somatic K-Ras mutation), attain oncogenic properties only in depalmitoylated state which favor protein intracellular trafficking by detachment from hydrophobic plasma membrane. In line, mutant K-Ras protein co-localize on outer mitochondrion membrane and interact with glycolytic enzymes (hexokinase-1 and -2) only in depalmitoylated state. This interaction induce K-Ras oncogenic properties and increased glucose uptake and glycolysis even in the presence of abundant oxygen (Warburg effect). Curiously, we observed co-depletion of mitochondrial proteins including glycolytic hexokinase 2 with several lipases displaying increase depalmitoylase activity in short LUAD survivals.

(d) Surprisingly, an evident disagreement in the activity of enzymes involved in lipolysis and protein depalmitoylation (i.e. IAH1, ABHD12, LYPLA2) was discovered between LUAD survival subtypes. These essential metabolic differences were uncovered by our standard proteomic analysis and to our knowledge have not been reported. Since the inhibitors of serine lipases are promising targets in other RAS-mutant carcinomas, this metabolic vulnerabilities discovered in aggressive LUAD can be explored as promising therapeutic strategies in lung cancer.

Citation Format: Tatjana Sajic, Stephan Arni, Rudolf Aebersold, Sven Hillinger. Discrimination of aggressive tumor profiles in lung adenocarcinomas using activity based protein profiling by SWATH/DIA-MS mode [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1887.