Detection of Tumor Cell-Specific mRNA and Protein in Exosome-Like Microvesicles from Blood and Saliva

Abstract

The discovery of disease-specific biomarkers in oral fluids has revealed a new dimension in molecular diagnostics. Recent studies have reported the mechanistic involvement of tumor cells derived mediators, such as exosomes, in the development of saliva-based mRNA biomarkers. To further our understanding of the origins of disease-induced salivary biomarkers, we here evaluated the hypothesis that tumor-shed secretory lipidic vesicles called exosome-like microvesicles (ELMs) that serve as protective carriers of tissue-specific information, mRNAs, and proteins, throughout the vasculature and bodily fluids. RNA content was analyzed in cell free-saliva and ELM-enriched fractions of saliva. Our data confirmed that the majority of extracellular RNAs (exRNAs) in saliva were encapsulated within ELMs. Nude mice implanted with human lung cancer H460 cells expressing hCD63-GFP were used to follow the circulation of tumor cell specific protein and mRNA in the form of ELMs in vivo. We were able to identify human GAPDH mRNA in ELMs of blood and saliva of tumor bearing mice using nested RT-qPCR. ELMs positive for hCD63-GFP were detected in the saliva and blood of tumor bearing mice as well as using electric field-induced release and measurement (EFIRM). Altogether, our results demonstrate that ELMs carry tumor cell–specific mRNA and protein from blood to saliva in a xenografted mouse model of human lung cancer. These results therefore strengthen the link between distal tumor progression and the biomarker discovery of saliva through the ELMs.

Integrated Magneto–Electrochemical Sensor for Exosome Analysis

“…To capture exosomes, we used magnetic beads that were coated with antibodies against tetraspanin, transmembrane proteins enriched in exosomes 5, 31, 32 . We first compared signal levels with differently sized beads (diameters, 2.7 μ m and 8.8 μ m).…”

Exosome mediated communication within the tumor microenvironment

“…In certain disorders of the central nervous system, numerous proteins including β-amyloid protein, α-synuclein and superoxidedismutase have also been found to be released from exosomes and are implicated in the pathogenesis of these diseases [73][74][75][76][77]. In patients with cancer, TEX represent a large portion of the circulating exosome population and elevated levels of tumor specific proteins are found in the blood of cancer patients [78].…”

Combination of IL-6, IL-10, and MCP-1 with traditional serum tumor markers in lung cancer diagnosis and prognosis

“…Lung cancer is a malignancy of the respiratory system, with the highest incidence and mortality rates among all malignancies (Reddy et al, 2014;Yang et al, 2014). The global mortality rate of lung cancer is rapidly rising; currently, China has the highest incidence and mortality rates of lung cancer, with an increasing number of younger patients being affected as compared to the past 20 years (Bhora et al, 2014;Burns and Stabile, 2014;Genestreti et al, 2014).…”