Abstract 5199: Distinct expression pattern of microRNAs bioinformatically predicted to target SATB1 in human breast cancer

Abstract

Abstract Recently, genome organizer protein special AT-rich sequence-binding protein 1(SATB1) has been reported to promote a metastatic phenotype and correlate with poor prognosis in breast cancer. The mechanism of SATB1 elevation in breast cancer remains elusive. This study was to investigate whether microRNAs (miRNAs) play a role in modulating SATB1 expression in ductual breast cancer by using archival formalin-fixed and paraffin-embedded (FFPE) clinical samples. Firstly, four canonical target prediction databases, including TargetScan, PicTar, miRanda and miRDB, were utilized to predict the interaction between miRNA and the 3′-UTR of SATB1 mRNA. The results of the prediction software programs were then integrated by displaying Venn diagram. Secondly, the Qiagen miRNeasy FFPE kit was used to isolate total RNA from 93 specimens with primary invasive ductual breast cancer. Expression of candidate miRNA transcriptional levels was measured using TaqMan MicroRNA Assays with miRNA-specific stem loop primers by relative real-time quantitative RT-PCR. The relative levels of miRNA expression were calculated from the relevant signals by normalization with the signal for RNU6B miRNA expression in each sample. Meanwhile, SATB1 protein expression levels were assessed by immunohistochemistry(IHC). Finally, correlations between the expression levels of these miRNAs and SATB1 were analyzed. Overall 22 miRNAs, 24 miRNAs, 76 miRNAs and 75 miRNAs were found by TargetScan, PicTar, miRanda and miRDB, to target SATB1 respectively, whereas only miR-7, miR-21, miR-23a, miR-23b, miR-34a and miR-155 were found by all four programs to be predicted to regulate SATB1. Quantitative RT-PCR detection analysis showed that expression levels of miR-34a were much higher in SATB1-negative than in SATB1-positive tumors (p<0.001). whereas lower miR-7 expression showed a strong trend toward an association with elevated SATB1 expression (P = 0.056). We then extended the analysis of miR-34a expression in breast cancer tissues to include all scores for SATB1 protein expression, assessed semiquantitatively by IHC. miR-34a expression levels were gradually decreased as SATB1 protein scores increased. Moreove, our quantitative RT-PCR results showed no differences in miR-21, miR-23a, miR-23b, and miR-155 expression between SATB1-negative and SATB1-positive tumors. We thus conclude that SATB1 maybe a novel target of miR-34a in human breast cancer. Downregulation of miR-34a promotes human breast cancer to progress through reduced repression of SATB1. Restoration of miR-34a may prove therapeutic in breast cancer patients in which aberrant SATB1 expression plays a role. Note: This abstract was not presented at the meeting. Citation Format: Weiming Duan, Zixing Chen, Li Yao, Min Tao, Kai Chen, Wei Liu, Jiannong Cen. Distinct expression pattern of microRNAs bioinformatically predicted to target SATB1 in human breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5199. doi:10.1158/1538-7445.AM2014-5199