Salivary Exosome Proteomics and Bioinformatics Analysis in 7,12-Dimethylbenz[a]anthracene-Induced Oral Cancer with Radiation Therapy-A Syrian Golden Hamster Model.

Wen-Chen Wang,Yin-Hwa Shih,Wan-Chen Lan,Yuk-Kwan Chen,Ming-Yii Huang,Tzong-Ming Shieh

doi:10.3390/diagnostics12010065

Abstract

Exosomes carry cellular proteins and contain molecules that can be potential biomarkers of diseases. This study used a Syrian golden hamster model of 7,12-dimethylbenz[a]anthracene (DMBA)-induced oral squamous cell carcinoma with radiation therapy to exclude the confounding factors that may affect outcomes in clinical studies, and re-examine the role of exosomes during tumorigenesis. We used data-dependent acquisition-based quantitative proteomics and bioinformatics analyses and found unique proteins present (desmocollin-2) or absent (Glucagon-cAMP-PKA-CREB pathway-related proteins) in the salivary exosomes of the pre-radiation DMBA-treated group (PreD). Comparing our data to other studies, salivary exosomes in the PreD group were found carrying proteins that the tumor mass does not express and lacking the proteins needed during tumorigenesis. Immunohistochemistry staining showed p53 expression but a negative apoptotic signal in the PreD tumor tissue. We thus suggest that inhibition of desmocollin-2 expression in tumor tissue may impede the activation of cell apoptosis. However, both the origin of the salivary exosomes and main role of the salivary exosome proteins should be clarified in future studies.

Highlights

Exosomes are extracellular nanovesicles with sizes between 30–150 nm secreted by cells carrying biomolecules and which play a role in physiological and pathological processes [1,2]
Both pre- and post-radiation salivary exosomes were isolated by ultracentrifugation, and exosomal protein was extracted for differential protein expression analysis
HE staining showed that the tumor masses of the pre-radiation DMBA-treated group (PreD) and PostD groups were poorly differentiated (Figure 2F,H) and the PostD tissue showed shrinkage and apoptosis (TUNEL positive) after six rounds of radiation (Figure 2D,P)

Summary

Introduction

Exosomes are extracellular nanovesicles with sizes between 30–150 nm secreted by cells carrying biomolecules and which play a role in physiological and pathological processes [1,2]. Exosomes exist in body fluids including blood, urine, saliva, breast milk, cerebrospinal fluid, and peritoneal fluid [3]. The molecules of salivary exosomes are similar to those in the exosomes of different origins, such as urinary exosomes [4] and serum exosomes [5]. Salivary exosome proteins reflect the microenvironmental changes around local lesions as well as the systematic conditions during tumorigenesis [6]. Several exosomal molecules (DNA, RNA, and proteins) [7,8,9,10] have been established as cancer biomarkers. Some of the exosomal markers identified in cancer specimens support the idea that cancer cells release exosomes around their microenvironment and promote cancer progression [11]

Methods

Results

Conclusion