CD5L as an Extracellular Vesicle-Derived Biomarker for Liquid Biopsy of Lung Cancer

Abstract

Cancer screening and diagnosis can be achieved by analyzing specific molecules within serum-derived extracellular vesicles (EVs). This study sought to profile EV-derived proteins to identify potential lung cancer biomarkers. EVs were isolated from 80 serum samples from healthy individuals and cancer patients via polyethylene glycol (PEG)-based precipitation and immunoaffinity separation using antibodies against CD9, CD63, CD81, and EpCAM. Proteomic analysis was performed using 2-D gel electrophoresis and matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI–TOF MS). The expression of proteins that were differentially upregulated in the EVs or tissue of lung cancer samples was validated by Western blotting. The area under the curve (AUC) was calculated to assess the predictability of each differentially expressed protein (DEP) for lung cancer. A total of 55 upregulated protein spots were selected, seven of which (CD5L, CLEC3B, ITIH4, SERFINF1, SAA4, SERFINC1, and C20ORF3) were found to be expressed at high levels in patient-derived EVs by Western blotting. Meanwhile, only the expression of EV CD5L correlated with that in cancer tissues. CD5L also demonstrated the highest AUC value (0.943) and was found to be the core regulator in a pathway related to cell dysfunction. Cumulatively, these results show that EV-derived CD5L may represent a potential biomarker—detected via a liquid biopsy—for the noninvasive diagnosis of lung cancer.

Reduced Plasma Extracellular Vesicle CD5L Content in Patients With Acute-On-Chronic Liver Failure: Interplay With Specialized Pro-Resolving Lipid Mediators

“…Nevertheless, our main interest was the composition of isolated EVs and whether this parameter could provide insight into the possible physiological relationship between CD5L and lipid mediators. The results revealed that CD5L is present in EVs purified from plasma, in agreement with previous reports ( 5 , 27 ). Interestingly, our data show that the EV cargo of CD5L undergoes significant changes during the course of liver pathology, thereby suggesting that CD5L is not a constitutive biomarker of circulating EVs.…”

Exosomes in Lung Cancer: Actors and Heralds of Tumor Development

“…Four of them, SRGN, TPM3, THBS1 and HUWE1, presented a combined AUC of 0.90 [114]. Another recent study identified CD5L as another potential biomarker [74]. This protein, an apoptosis inhibitor, was found to be overexpressed in both exosomes and cancer tissues and presented an AUC for lung cancer diagnosis of 0.943.…”

“…Another important issue is that exosomes can easily adhere to working material surfaces, with the consequent risk of either losing interesting exosomes, high background signal or both [13]. Finally, some protocols combine successive isolation and purification methods, such as polymer precipitation and immunoaffinity purification, rendering a fairly pure population of exosomes [33,74].…”

“…Blood usually contains high concentrations of exosomes, 10 8 -10 11 per mL, but most of them derive from blood cells, and tumor exosomes usually account for only a small proportion of the total circulating exosomes, making their isolation cumbersome [77]. The use of antibodies against exposed tumor antigens at the exosome membrane can be used to purify cancer exosomes [74]. This procedure can turn out well when specific tumor antigens exist, such as prostate specific antigen (PSA) in the case of prostate cancer exosomes, but this is not the case in lung cancer.…”

Exosomes in the lung cancer microenvironment: biological functions and potential use as clinical biomarkers

“…This result suggests that CD5L may be another potential biomarker for noninvasive diagnosis of NSCLC. The EVs were detected to be about 76-194 nm in diameter, which included the category of exosomes [ 112 ]. In addition, the combination of miR-21-5p, miR-223-3p, miR-155-5p and miR-126-3p may be a potential diagnostic biomarker for lung cancer [ 113 ].…”