Exosomes Mediated Transfer of Circ_UBE2D2 Enhances the Resistance of Breast Cancer to Tamoxifen by Binding to MiR-200a-3p
MEDICAL SCIENCE MONITOR
Authors: Hu, Ke; Liu, Xianhao; Li, Yi; Li, Qinyang; Xu, Yijun; Zeng, Wei; Zhong, Guocheng; Yu, Changhua
Abstract
Background: Circular RNA UBE2D2 (circ_UBE2D2) has been found to be involved in the progression of breast cancer. Exosomes are critical mediators of intercellular communication, however, the function of exosomal circ_UBE2D2 in breast cancer remains vague. Material/Methods: Cell viability was measured by Cell Counting Kit-8 assay. Western blot was used to detect the levels of estrogen receptor alpha (ERa), E-cadherin, vimentin, CD9, and CD63. Migrated and invaded cells were examined using Transwell assay. Circ_UBE2D2 and microRNA (miR)-200a-3p levels were detected using quantitative real-time polymerase chain reaction. Exosomes were isolated by ultracentrifugation method. The interaction between circ_UBE2D2 and miR-200a-3p was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. Murine xenograft model was established to conduct in vivo experiments. Results: We found that circ_UBE2D2 was upregulated in breast cancer tamoxifen-resistant tissues and cell lines, and circ_UBE2D2 deletion mitigated tamoxifen resistance in breast cancer cells. Circ_UBE2D2 was also significantly loaded in exosomes isolated from resistant cells and could be transferred to parental cells. MiR-200a-3p was a target of circ_UBE2D2, and we demonstrated that exosomes mediated transfer of circ_UBE2D2 interacted with miR-200a-3p to enhance tamoxifen resistance of breast cancer cells by regulating cell viability, metastasis, and the level of ER alpha in vivo and in vitro. Conclusions: Exosomes mediated transfer of circ_UBE2D2 reinforced tamoxifen resistance in breast cancer by binding to miR-200a-3p, providing new insights into the boost of the effectiveness of tamoxifen on breast cancer patients.
Normalization of gene expression using SYBR green qPCR: A case for paraoxonase 1 and 2 in Alzheimer's disease brains
JOURNAL OF NEUROSCIENCE METHODS
Authors: Leduc, Valerie; Legault, Veronique; Dea, Doris; Poirier, Judes
Abstract
Validating the expression stability of reference genes is crucial for reliable normalization of real-time quantitative PCR (qPCR) data, but relatively few studies have investigated this issue in brain human tissues. The present study thus aimed at identifying in human post-mortem brain tissues a set of suitable endogenous reference genes (ERG) for the expression analysis of potential candidate genes associated with Alzheimer's disease (AD). The mRNA levels of ten common ERGs (ACTB, GAPDH, GPS1,GUSB,M-RIP, PGK1, POL2RF, PPIA, UBE2D2, and YES1) were determined in the frontal cortex of autopsy-confirmed AD and non-demented control cases (n = 20) using SYBR Green technology. Then, these levels were ranked according to their expression stability using three software applications: geNorm, NormFinder and Best-Keeper. Whereas PPIA and UBE2D2 were among the ERGs with the most reliable expression. ACTS was the worst. Subsequently, using PPIA and UBE2D2 as ERGs for normalization, the mRNA levels of paraoxonase 1 (PON1) and paraoxonase 2 (PON2) were quantified in the frontal cortex of AD and control cases (n = 80) and analyzed using the REST 2009 program. Our results indicate that both paraoxonases are expressed in the human frontal cortex and that PON2 but not PON1 mRNA levels are up-regulated in AD relative to non-demented controls. However, re-analysis of the results by ANCOVA indicated that the significance of the difference between AD and control groups depended upon the ERG used for normalization. The use of a computational method allowing the inclusion of possible confounding factors is thus recommended for the analysis of data. (C) 2011 Published by Elsevier B.V.