miR-342 is associated with estrogen receptor-α expression and response to tamoxifen in breast cancer

Abstract

Estrogen receptor-α (ERα) is essential for estrogen-dependent growth and its level of expression is a crucial determinant of response to endocrine therapy and prognosis in ERα-positive breast cancer. Breast cancer patients show a wide range of ERα expression levels which change in individual patients during disease progression and in response to systemic therapies. However, little is known concerning how the expression of ERα is regulated in human breast cancer. Recently, several microRNAs (miRNAs) have been identified to regulate ERα expression and to predict ER, progesterone receptor (PR) and human epidermal growth factor 2 (HER2) status. The expression levels of miR-342 and ERα mRNA were analyzed in human breast cancer samples and cell lines by quantitative reverse transcription (RT)-PCR analysis. The correlations between the expression levels of miR-342 and clinicopathological factors were analyzed. Statistically significant associations were observed between miR-342 and ER, HER2 and vascular endothelial growth factor (VEGF) status in the human breast cancer samples and the levels of miR-342 gradually increased as ERα mRNA expression increased. Moreover, ectopic overexpression of miR-342 upregulated the expression levels of the ERα mRNA and significantly sensitized the MCF-7 cells to tamoxifen-induced apoptosis and inhibition of cellular proliferation. These results suggested that miR-342 expression is positively correlated with ERα mRNA expression in human breast cancer and that it may be a significant marker for predicting tamoxifen sensitivity in ERα-positive breast cancer and a potential target for restoring ERα expression and responding to antiestrogen therapy.

miR-342-3p targets RAP2B to suppress proliferation and invasion of non-small cell lung cancer cells

“…Importantly, overexpression of miR-342 has been shown to inhibit cell proliferation and invasion in cervical and colorectal cancer [17,18]. Diagnostic and prognostic values of miR-342 expression have additionally been highlighted in acute myeloid leukemia, breast cancer, and colon cancer [27][28][29]. In the current study, we established a role of miR-342-3p as an effective NSCLC suppressor.…”

Combined Label-Free Quantitative Proteomics and microRNA Expression Analysis of Breast Cancer Unravel Molecular Differences with Clinical Implications

“…miR-342 expression has been beforehand described as significantly higher in ER þ samples, and was included in a predictor of ER status together with miR-135b and miR-190 (33). Moreover, miR-342 expression was positively correlated with ERa mRNA expression in human breast cancer (34). miR-205 was significantly underexpressed in triple-negative primary breast cancers when compared with tumor-associated normal samples.…”

Recent trends in microRNA research into breast cancer with particular focus on the associations between microRNAs and intrinsic subtypes

“…The loss of metadherin has been shown to restore sensitivity to endocrine therapy and is correlated with disease-free survival in ER-positive patients. 58 He et al 36 demonstrated that miR-342 expression was positively correlated with ER expression and also found that the introduction of miR-342 into estrogendependent breast cancer cell lines enhanced their sensitivity to tamoxifen-induced apoptosis. In agreement with this, Cittelly et al 59 reported that the downregulation of miR-342 expression was associated with tamoxifen resistance.…”

“…34 MiR-342 influences the ER expression level and the response to tamoxifen. 35,36 MiR-10b, miR-26a and miR-153 have been suggested to be potential biomarkers of triple-negative breast cancer (TNBC). 37 miRNAs associated with each subtype of breast cancer are shown in Table 3.…”