Abstract 487: Usefulness of exosome quantification by cholesteryl ester transfer protein activity as a biomarker for human esophageal squamous cell carcinoma (ESCC)

Abstract Exosomes are small membrane vesicles (30-100 nm) and are thought to play an important role in tumor progression, chemoresistance, dormancy etc. However, the exosome dynamics and transportation between cancer cells and the other cells are still unclear. In addition, although it is common method to quantify exosomes using standard protein quantification methods, it is actually incorrect. In this study, we assessed the exosome dynamics with mouse model and quantify plasma exosome by cholesteryl ester transfer protein activity, which is known to be enriched within exosomes. We analyzed the relationship between exosome quantification and clinical characters in ESCC patients. In order to image and analyze the movement of cancer cell-derived exosomes, green fluorescent protein (GFP)-tagged CD63, which is a general marker of exosomes, was expressed in human esophageal squamous cancer cell line TE2. Mouse model of human ESCC were then established by s.c. injection of TE2-CD63-GFP or TE2 cell lines. Eight weeks after injection, the tumor, blood and other organs were harvested and imaged with fluorescence. Our data indicates tumor derived exosome can emitted from the tumor and circulate in the blood flow. Quantification of plasma exosome in ESCC patients (n = 64) and no malignant patient (n = 10) were performed by measurement of cholesteryl ester protein activity, and then analyzed the relationship between the exosome number and the patients’ clinical characteristics, such as age, sex, TNM classification, prognosis, tumor marker. Our data indicates the exosome number was higher in ESCC patients than no malignant patients (P = 0.0014). Althogh there were no difference in tumor depth, lymph node status, distant metastasis, the exosome number can be a prognostic marker for ESCC (P = 0.04). Citation Format: Yasunori Matsumoto, Masayuki Kano, Yasunori Akutsu, Naoyuki Hanari, Isamu Hoshino, Kentaro Murakami, Akihiro Usui, Hiroshi Suito, Masahiko Takahashi, Ryota Otsuka, Hisahiro Matsubara. Usefulness of exosome quantification by cholesteryl ester transfer protein activity as a biomarker for human esophageal squamous cell carcinoma (ESCC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 487.