Mirna-218 Is Frequently Downregulated in Malignant Breast Tumors: A Footprint of Epstein-Barr Virus Infection

Background & objective: the role of epstein-barr virus in development of breast cancer is frequently studied. in this regard, mirnas are among the contributing elements in the molecular pathophysiology of ebv-related diseases. in addition, a growing number of host mirnas are believed to be implicated in pathogenesis of breast cancer. mir-218 is a tumor suppressive mirna that is subjected to dysregulation in various ebv-associated cancers. we aimed to investigate the frequency of ebv and its relationship with expression status of tumor suppressive mir-218 in breast cancer and adjacent normal tissue. methods: a total number of 51 fresh malignant breast cancer tissues (cases) and their adjacent normal tissues (controls) were collected. nested-pcr and rt-qpcr were set to identify ebv frequency and mir-218 expression in cases and controls, respectively. results: out of all samples, 6.8% (7/102) comprising 11.6% (6/51) in malignant tissues and 1.9% (1/51) in normal control tissues were positive for ebv (p<0.05). quantitative data showed that mir-218 was significantly downregulated in malignant tissues compared to control tissues (p<0.0001). in addition, reduced expression of mir-218 was associated with adverse clinical outcomes, metastasis, and higher grades of malignancy. given the presence of ebv, lower expression of mir-218 was observed in breast cancer group in comparison with normal group (p<0.05). conclusion: our results raise the possibility of the relation between ebv infection and mir-218 downregulation in breast cancer and propose further investigations in this regard.