Abstract
MicroRNAs (miRNAs) regulate many cellular activities, including cancer development, progression, and metastasis. Some miRNAs are involved in breast cancer (BC) migration and invasion, thus affect patients’ prognosis. Microarray analysis was performed to compare miRNA expression in BC tissues, and results confirmed by qPCR. BC cell migration and invasion were studied in vitro with MDA‐MB‐231 cells using microplate transwell assays. miRNA targeting was investigated using luciferase assays, qPCR, and Western blot analysis in cells with overexpression of miRNA mimics. Knockdown of miRNA targets was performed using target siRNA lentiviral infection. Results show that microRNA‐141 (miR‐141) was downregulated in breast cancer tumor tissues compared with matched surrounding tissues. Downregulation of miR‐141 expression correlated with tumor stage, lymph node involvement, and expressions of PCNA, Ki67, and HER2. Overexpression of miR‐141 inhibited BC cell proliferation, migration, and invasion in vitro. ANP32E gene was selected as one putative target for further studies based on results from in silico analysis. Results from a dual‐luciferase reporter system suggested ANP32E as a direct target of miR‐141. Overexpression of miR‐141 downregulated ANP32E expression at both mRNA and protein levels in BC cells. Knockdown of ANP32E inhibited BC cell proliferation, migration, and invasion in vitro, mimicking the effect of the overexpression of miR‐141. Our study revealed important roles miR‐141 plays in BC growth and metastasis. Moreover, for the first time, we identified ANP32E as one of the miR‐141 targets, and demonstrated its involvement in the regulation of cell proliferation, migration, and invasion.
Highlights
Breast cancer (BC) is the most frequently diagnosed cancer and the leading cause of cancer death in females that affected an estimated three million women worldwide in 2008 [1]
About half the breast cancer cases and 60% of the deaths are estimated to occur in developing countries, and most of the deaths are due to metastasis
We found that miR-1 41 was downregulated in BC, and miR-141 expression level negatively correlated with clinicopathologic features such as expressions of Ki67, HER2, and PCNA. miR-1 41 overexpression inhibited BC cell proliferation, migration, and invasion in vitro, at least in part through targeting of ANP32E
Summary
Breast cancer (BC) is the most frequently diagnosed cancer and the leading cause of cancer death in females that affected an estimated three million women worldwide in 2008 [1]. About half the breast cancer cases and 60% of the deaths are estimated to occur in developing countries, and most of the deaths are due to metastasis. MicroRNAs (miRNAs), a class of small noncoding RNAs, have been shown to play roles in many aspects of cancer biology, including proliferation, apoptosis, invasion/metastasis, and angiogenesis. The miRNAs, which bind to the 3′-UTR of their target mRNAs, are proposed to regulate the expression of at least 30% of all protein-coding genes [2]. MiRNAs can act either as oncogenes or as tumor suppressors depending on their target mRNAs. Numerous studies have shown that abnormal miRNA expression was related to cancer invasion, metastasis, and resistance to chemotherapy. The expression of miR-200 family members, including miR-200a, miR-200b, miR-200c, miR-141, and miR-429, was lost in invasive BC cell lines [6]. In BC cells, miR-141 targets EGFR, and inhibits its translation [7]. miR-141 was found to regulate cancer cell growth and metastasis in lung cancer, liver cancer, colorectal cancer, gastric cancer, renal cancer, and prostate cancer [8,9,10,11,12,13]
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