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RESEARCH PRODUCT

Exosomes in NSCLC as a source of biomarkers

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Abstract Background Exosomes are small membranous vesicles (around 40-130 nm), that have been detected in different biological samples, that play a key role in NSCLC and being relevant in stem cell differentiation as well. The main objective of this study was to analyze the exosomes cargo from NSCLC cell cultures growth in monolayer (2D) and suspension conditions (3D, lung tumorespheres). Methods Cultures were established from NSCLC resected patients and cell lines. Exosomes isolation was performed by ultracentrifugation. Characterization was carried out by NTA, electron microscopy, immunoblot and flow cytometry. Mutational status of EGFR and RAS genes was analyzed by BEAMing dPCR. Transcriptomic analysis has been carried out from exosomal RNA with microarrays, (p ≤ 0.01). Consequently, XAGE1B (significantly expressed gene in exosomes) was analyzed by RTqPCR in 189 paired fresh-frozen tumor and normal tissue samples of resected NSCLC. Prognostic value was assessed by Kaplan‐Meier curves (log rank‐test), considering significant p  Results Exosomal characterization through NTA and electron microscopy showed an exosomes size from 108-125 nm. Specific markers were detected by IB and FC. Mutational analysis of EGFR and RAS genes in exosomes shown the same pattern displayed by the origin cells. Transcriptomic analysis showed that the expression of mRNAs, miRNAs and precursors were significantly different between 3D and 2D-derived exosomes. A pathway enrichment was carried out to know in which processes (cancer-related) are involved. Significant differential expression was also found between ADC vs SCC–derived exosomes. Concretely, XAGE1B is overexpressed in ADC-derived exosomes (p = 0.00003). This overexpression in ADC was validated in NSCLC cohort (p = 0.002). Furthermore, it has revealed a significant association with patient prognosis for overall survival in the ADC group (n = 74)(OS 49.8 vs. NR months, p = 0.043). Conclusions Differences in exosomal cargo have been observed between: i) 3D vs. 2D cultures and ii) ADC vs. SCC. In addition, the same mutational pattern was detected in exosomes as compared with parental cells. Therefore, exosomes can be a useful source of biomarkers in NSCLC analysis. Supported by grant GV/2018/026, PI18/00266, & AECC Valencia. Legal entity responsible for the study Fundacion de Investigacion del Hospital General Universitario de Valencia. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.