Oncogenic miRNAs Identified in Tear Exosomes From Metastatic Breast Cancer Patients
Sachiko Inubushi, Hiroki Kawaguchi, Sachiko Mizumoto, Tomonari Kunihisa, Motoi Baba, Yukiya Kitayama, Toshifumi Takeuchi, Robert M. Hoffman, Ryohei Sasaki
Abstract
BACKGROUND/AIM: Exosomes are produced by normal and cancer cells. Exosomes are found in the serum of cancer patients and have been used for diagnosis and prognosis. Recently tears from non-cancer patients have been found to contain exosomes. In the present report we describe tears from advanced breast-cancer patients. MATERIALS AND METHODS: We found oncogenic miRNAs in the exosomes isolated from tear fluids obtained from five patients with metastatic breast cancer and compared them with tear exosomes form eight healthy volunteers. RESULTS: Tear exosomes had a significantly higher quantity of exosome markers than serum exosomes (CD9, CD63). Tear exosomes were subjected to quantitative reverse-transcription polymerase reaction (qRT-PCR), and western blot analysis to elucidate the status of miRNAs, previously reported in serum from patients with metastatic breast cancer. qRT-PCR and western-blot analysis revealed that breast-cancer-specific miR-21 and miR-200c were highly expressed in tear exosomes from metastatic breast cancer patients in contrast to tear exosomes from healthy volunteers. CONCLUSION: Tear exosomes can be a potential source of diagnostic and prognostic biomarkers for metastatic breast cancer, and possibly other cancers or diseases.