Proteomic Analyses of Fibroblast- and Serum-Derived Exosomes Identify QSOX1 as a Marker for Non-invasive Detection of Colorectal Cancer.

Nicole Ganig,Kuailu Lin,Franziska Baenke,Mathieu Pecqueux,Adrian M Seifert,Heike Polster,Venkatesh S Rao,Nuh N Rahbari,May-Linn Thepkaysone,Martin Schneider,Jürgen Weitz,Fang Cheng Wong,Dominic Helm,Christoph Kahlert,Lena Seifert

doi:10.3390/cancers13061351

Abstract

Simple SummaryEarly diagnosis of colorectal cancer (CRC) is crucial to improve patient outcomes. The tumour microenvironment immediately adapts to malignant transformations, including the activation of fibroblasts in the connective tissue nearby. In this study, we investigated fibroblast activity-related protein secretion via extracellular vesicles (EVs). QSOX1, a protein identified to be significantly reduced in activated fibroblasts and derived EVs, was also found to be significantly reduced in circulating blood plasma EVs of CRC patients as compared to control patients. Hence, blood plasma EV-associated QSOX1 represents a promising platform for diagnostic CRC screening.The treatment of colorectal cancer (CRC) has improved during the last decades, but methods for crucial early diagnosis are yet to be developed. The influence of the tumour microenvironment on liquid biopsies for early cancer diagnostics are gaining growing interest, especially with emphasis on exosomes (EXO), a subgroup of extracellular vesicles (EVs). In this study, we established paired cancer-associated (CAFs) and normal fibroblasts (NF) from 13 CRC patients and investigated activation status-related protein abundance in derived EXOs. Immunohistochemical staining of matched patient tissue was performed and an independent test cohort of CRC patient plasma-derived EXOs was assessed by ELISA. A total of 11 differentially abundant EV proteins were identified between NFs and CAFs. In plasma EXOs, the CAF-EXO enriched protein EDIL3 was elevated, while the NF-EXO enriched protein QSOX1 was diminished compared to whole plasma. Both markers were significantly reduced in patient-matched CRC tissue compared to healthy colon tissue. In an independent test cohort, a significantly reduced protein abundance of QSOX1 was observed in plasma EXOs from CRC patients compared to controls and diagnostic ROC curve analysis revealed an AUC of 0.904. In conclusion, EXO-associated QSOX1 is a promising novel marker for early diagnosis and non-invasive risk stratification in CRC.

Highlights

With an incidence of 6.1%, colorectal cancer (CRC) is the third most common diagnosed cancer worldwide and reflects the second leading cause of cancer-related deaths (9.2%) [1]
To investigate alterations in fibroblasts of the tumour microenvironment (TME) upon interaction with CRC cells, cancer-associated fibroblasts (CAFs) were successfully established from malignant colorectal tissue of three CRC patients following surgical resection (Table S1 and Figure S2)
Of note, induced levels of fibroblast activation protein α (FAPα) in CAFs were only detected in patient 3

Summary

Introduction

With an incidence of 6.1%, colorectal cancer (CRC) is the third most common diagnosed cancer worldwide and reflects the second leading cause of cancer-related deaths (9.2%) [1]. In approximately 21% of all diagnosed CRC cases in the US, patients present at an already advanced, metastatic stage [6]. Total tumour stroma and CAF-specific gene expression patterns were identified and revealed prognostic value in breast cancer [10], non-small cell lung cancer [11] and CRC [12,13]. As these signatures were examined in tissue or tissue-derived primary cells, their potential diagnostic value remains to be clarified

Objectives

Methods

Results