Oncogenic miRNAs Identified in Tear Exosomes From Metastatic Breast Cancer Patients

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.