Elevated exosomal lysyl oxidase like 2 is a potential biomarker for head and neck squamous cell carcinoma

Abstract

Objectives: The secretory enzyme lysyl oxidase like 2 (LOXL2) is speculated to contribute to tumor progression through its functions in the remodeling of extracellular matrix and epithelial-mesenchymal transition. We previously identified elevated expression of LOXL2 in metastatic human head and neck squamous cell carcinoma (HNSCC) cells in a mouse lymph node metastases model. Here we performed a case series study examining LOXL2 expression levels in human serum from HNSCC patients to evaluate whether LOXL2 is worth evaluation in a large cohort study.Methods: LOXL2 protein levels in three serum samples from HNSCC patients were assessed by immunoblotting and LOXL2 tissue expression was examined in one human tongue squamous cell carcinoma (SCC) tissue by immunohistochemistry as a representative of HNSCC tissue. Serum samples were further fractionated in exosomes and supernatants by ultracentrifugation, which were then subjected to immunoblot and in vitro LOX activity analyses. Exosomal LOXL2 levels of 36 serum samples from HNSCC patients and seven healthy volunteers were measured using polymer sedimentation exosome preparation followed by ELISA measurement and subjected to statistical analyses.Results: Immunoblot analyses revealed that LOXL2 was present in serum exosomal fractions from three HNSCC patients, and we observed approximately threefold higher levels of LOXL2 in HNSCC patients compared with three healthy volunteers. Immunohistochemical LOXL2 staining was detected in HNSCC cells in addition to non-cancerous lipid tissues and some muscles in human tongue HNSCC tissue. Further measurements of exosomal LOXL2 by ELISA showed over ninefold higher mean LOXL2 levels in patients compared with controls. Statistical analysis revealed a correlation between elevated serum exosomal LOXL2 levels and low-grade, but not high-grade, HNSCC.Conclusions: Our case series study that elevated serum exosomal LOXL2 levels exhibited a correlation with low-grade HNSCCs. A follow-up large cohort clinical study will be required to determine the potential clinical utility of LOXL2 as a new biomarker and/or therapy target for HNSCCs.

Exosomal cargoes in OSCC: current findings and potential functions

“…They isolated exosomes and found different miRNA loading patterns similar to the loading patterns of blood exosomes, suggesting that circulating exosomes can be a more reliable method in evaluating tumors ( Rabinowits et al, 2017 ). Sanada et al (2020) examined the expression levels of secreted lysyl-oxidase-like 2 (LOXL2) in pharyngeal and tongue cancer patient serum and found that elevated serum exosomes LOXL2 levels are associated with low-grade oral cancer. All these discoveries of exosomes provide new ideas for the non-invasive disease diagnosis method.…”

The roles of extracellular vesicles in the development, microenvironment, anticancer drug resistance, and therapy of head and neck squamous cell carcinoma

“…Immunoblot analyses revealed that LOXL2 was present in the serum exosomal fractions from three HNSCC patients, and Sanada et al observed approximately threefold higher levels of LOXL2 in the HNSCC patients compared with three healthy volunteers. The hypoxic microenvironment may stimulate tumour cells to generate miRNA-21-rich EXOs that are delivered to normal cells to promote premetastatic behaviours [70]. Similarly, bioinformatics analysis has shown that miR-21-enriched EVs are associated with increased HNSCC metastasis and poor survival [71].…”

Exosomes: Potential Biomarkers and Functions in Head and Neck Squamous Cell Carcinoma

“…In addition, previous studies had verified that LOXL2 mRNA expression was up-regulated in metastatic HNSCC cells compared with non-metastatic cells ( Demory Beckler et al, 2013 ). Taken together, these results suggest that serum exosome LOXL2 levels are only associated with early-stage HNSCC, and may serve as biomarkers for early diagnosis and a potential target for therapeutic intervention ( Cox et al, 2016 ; Sanada et al, 2020 ). Both protein and mRNA levels of Annexin A1 (ANXA1) were down-regulated in HNSCC.…”