Comprehensive microRNA-sequencing of exosomes derived from head and neck carcinoma cellsin vitroreveals common secretion profiles and potential utility as salivary biomarkers

Abstract

Exosomes are nano-scale, membrane encapsulated vesicles that are released by cells into the extracellular space and function as intercellular signaling vectors through horizontal transfer of biologic molecules, including microRNA (miRNA). There is evidence that cancer-derived exosomes enable the tumor to manipulate its microenvironment, thus contributing to the capacity of the tumor for immune evasion, growth, invasion, and metastatic spread. The objective of this study was to characterize differential secretion of exosomal miRNA by head and neck squamous cell carcinoma (HNSCC) and identify a set of candidate biomarkers that could be detected in non-invasive saliva samples. We isolated exosomes from conditioned media from 4 HNSCC cell lines and oral epithelial control cells and applied miRNA-sequencing to comprehensively characterize their miRNA cargo and compare transcript levels of each HNSCC cell line to that of oral epithelial control cells. A candidate set of miRNA differentially secreted by all 4 HNSCC cell lines was further evaluated in saliva collected from HNSCC patients and healthy controls. We observed extensive differences in exosomal miRNA content between HNSCC cells when compared to normal oral epithelial control cells, with a high degree of overlap in exosomal miRNA profiles between the 4 distinct HNSCC cell lines. Importantly, several of the exosomal miRNA secreted solely by cancer cells in culture were detected at substantially elevated levels in saliva from HNSCC patients relative to saliva from healthy controls. These findings provide important insight into tumor biology and yields a promising set of candidate HNSCC biomarkers for use with non-invasive saliva samples.

Salivary Exosomes: Emerging Roles in Systemic Disease

“…Currently, the study of salivary biomarkers has developed beyond oral diseases 84 - 86 to systemic diseases 87 , 88 , which has broadened the potential for systemic disease detection 89 , 90 . Recently, Langevin et al 91 , using miRNA sequencing, found that several salivary exosomal miRNAs, including miR-486-5p, miR-486-3p, and miR-10b-5p, were substantially overexpressed among a subset of head and neck squamous cell carcinoma patients compared to cancer-free controls, highlighting the use of salivary exosomal miRNAs as potential noninvasive cancer biomarkers. Zheng et al 70 used liquid chromatography tandem mass spectrometry to identify the contents of salivary exosomes in patients with inflammatory bowel disease (IBD), which is an intestinal immune-dysfunctional disease with unknown cause.…”

Exosomes and other extracellular vesicles in oral and salivary gland cancers

“…For example, exosomal miR‐486 and miR‐10b‐5p, which may participate in suppression of immune pathways and reprogramming of cellular metabolism, have been found at elevated levels in saliva of head and neck squamous cell carcinoma (HNSSC) patients. This result demonstrates that these exosomal miRNAs may serve as non‐invasive salivary biomarkers of HNSCC (Langevin et al, ). Rabinowits et al () also screened some exosomal miRNAs from both tumor samples and plasma of patients with tongue SCC as diagnostic biomarkers for tongue SCC.…”

Extracellular Vesicles in Oral Squamous Cell Carcinoma and Oral Potentially Malignant Disorders: A Systematic Review

“…Comparison of the microRNA present in exosomes isolated from the conditioned media from 4 HNSCC cell lines: H413 (from buccal mucosa OSCC), Detroit 562 (pharyngeal cancer metastatic to pleura), FaDu (hypopharyngeal cancer) and Cal 27 (tongue OSCC), with similarly isolated EVs from normal gingival keratinocytes identified 32 common differentially abundant microRNA in the 4 HNSCC cell lines [56]. Further, comparison of the microRNA present in EVs isolated from the saliva of OSCC patients (n = 5) and 5 cancer-free controls found several of the microRNA that were upregulated in cancer culture cells were increased in salivary exosomes of HNSCC patients when compared to controls [56].…”