miR-195 down-regulation is a distinctive biomarker of HER2 positive state in breast cancer

Abstract

Background: Breast cancer is the most common cancer among women worldwide. HER2-positive breast cancer accounts for nearly 20 of all cases. Upon targeted therapy resistance, these patients show fairly poor-prognosis. miRNAs have shown to be differentially expressed in HER2-positive cases that can decipher drug resistance. miR-195 down-regulation has been reported in breast cancer; however, very little is known about its expression particularly in HER2-positive breast cancers. Material and methods: qPCR was used to quantitatively measure the expression of miR-195 in normal, HER2-positive and HER2-negative fresh clinical samples. A computational approach was used to find unvalidated but potential targetome of miR-195. Results: miR-195 is down-regulated in breast cancer samples as compared to the normal controls. The level of down-regulation was significantly greater in HER2-positive tumors as compared to both normal and HER2-negative samples. Importantly, miR-195 down-regulation was demonstrated to be a potential diagnostic biomarker for distinguishing HER2-positive against both normal and HER2-negative samples. Besides, the in silico approach revealed that unvalidated miR-195 targetome play roles in oncogenic pathways related to breast tumorigenesis and progression. Conclusion: miR-195 is down-regulated in breast cancer, especially and significantly in HER2-positive cases. The expression of miR-195 could effectively be used as a distinctive diagnostic marker to discriminate HER2-positive from both normal and HER2-negative samples.