Abstract 3087: MicroRNA 141: A novel regulator of brain metastasis from breast cancer

Purpose: Brain metastasis poses a major treatment challenge and remains an unmet clinical need. Finding novel therapies to prevent and treat brain metastases requires an understanding of the biology and molecular basis of the process, which currently is constrained by a dearth of experimental models and specific therapeutic targets. The purpose of this study was to identify molecular mediators of brain metastasis from breast cancer using novel preclinical brain metastasis models we developed recently. Methods: GFP-labeled cells were injected via tail vein into SCID/beige mice and metastatic colonization to the brain and lung was evaluated by fluorescent stereomicroscope and histology 8-weeks after injection. miRNA microarray was performed with miRNA 3.0 Array. Stable knockdown and overexpression of miR-141 was achieved with lentiviral vectors. miR-141 serum levels in patients with metastatic breast cancer was measured using quantitative PCR and was associated with outcome data. Results: We developed novel brain metastasis models in which tail-vein injection of parental triple-negative and a HER2-overexpressing inflammatory breast cancer lines led to a high rate of brain metastases (67%) in SCID/Beige mice (SUM149, 6 of 9 mice; MDA-MB-IBC3, 10 of 15 mice). Sub-lines derived from brain metastasis (BrMS) or lung metastasis (LuMS) tissues were morphologically and molecularly distinct. The BrMS showed epithelial morphology and overexpressed epithelial markers and miR-141 while the LuMS showed mesenchymal morphology and overexpressed mesenchymal markers. Knockdown of miR-141 significantly inhibited metastatic colonization to the brain in both cell lines (miR-141 knockdown vs. control: SUM149, 0 of 8 mice vs. 6 of 9 mice, p = 0.009; MDA-MB-IBC3, 2 of 14 mice vs. 10 of 15 mice, p = 0.007). Ectopic expression of miR-141 in non-expressing MDA-MB-231 significantly enhanced brain metastatic colonization via tail-vein injection (5 of 9 mice vs. 0 of 10 mice, P = 0.02). On multivariate analyses high serum level of miR-141 was an independent predictor of progression free survival [HR 4.8 (95%CI, 2.6-8.7), P Conclusion: We have generated novel brain metastasis models, demonstrated miR-141 as a key regulator of brain metastasis and provided clinical evidence supporting the prognostic relevance of miR-141 in patients with brain metastasis. We propose that miR-141 should be examined as a biomarker and potential target for the prevention and treatment of brain metastases from breast cancer. Citation Format: Bisrat G. Debeb, Lara Lacerda, Simone Anfossi, Parmesh Diagaradjane, Khoi Chu, Lei Huo, Caimiao Wei, Richard Larson, Adam Wolfe, Wei Xu, Li Li, Daniel Smith, Cristina Ivan, Pamela Allen, Savitri Krishnamurthy, George Calin, Xiang Zhang, Thomas Buchholz, Naoto Ueno, James Reuben, Wendy Woodward. MicroRNA 141: A novel regulator of brain metastasis from breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3087. doi:10.1158/1538-7445.AM2015-3087