TGF-β upregulates miR-181a expression to promote breast cancer metastasis
Molly A. Taylor, … , David Danielpour, William P. Schiemann
Molly A. Taylor, … , David Danielpour, William P. Schiemann
Published December 17, 2012
Citation Information: J Clin Invest. 2013;123(1):150-163. https://doi.org/10.1172/JCI64946.
View: Text | PDF
Research Article Oncology

TGF-β upregulates miR-181a expression to promote breast cancer metastasis

Abstract

Late-stage breast cancer metastasis is driven by dysregulated TGF-β signaling, but the underlying molecular mechanisms have not been fully elucidated. We attempted to recapitulate tumor and metastatic microenvironments via the use of biomechanically compliant or rigid 3D organotypic cultures and combined them with global microRNA (miR) profiling analyses to identify miRs that were upregulated in metastatic breast cancer cells by TGF-β. Here we establish miR-181a as a TGF-β–regulated “metastamir” that enhanced the metastatic potential of breast cancers by promoting epithelial-mesenchymal transition, migratory, and invasive phenotypes. Mechanistically, inactivation of miR-181a elevated the expression of the proapoptotic molecule Bim, which sensitized metastatic cells to anoikis. Along these lines, miR-181a expression was essential in driving pulmonary micrometastatic outgrowth and enhancing the lethality of late-stage mammary tumors in mice. Finally, miR-181a expression was dramatically and selectively upregulated in metastatic breast tumors, particularly triple-negative breast cancers, and was highly predictive for decreased overall survival in human breast cancer patients. Collectively, our findings strongly implicate miR-181a as a predictive biomarker for breast cancer metastasis and patient survival, and consequently, as a potential therapeutic target in metastatic breast cancer.

Authors

Molly A. Taylor, Khalid Sossey-Alaoui, Cheryl L. Thompson, David Danielpour, William P. Schiemann

×

Figure 1

miR-181a expression is upregulated by TGF-β and correlates with the metastatic potential of breast cancer cells.

Options: View larger image (or click on image) Download as PowerPoint
miR-181a expression is upregulated by TGF-β and correlates with the meta...
(A and B) Nonmetastatic 67NR, systemically invasive 4T07, and broadly metastatic 4T1 cells were propagated in the absence or presence of TGF-β1 (5 ng/ml) for 6 days in either rigid (3 mg/ml collagen) or compliant 3D organotypic cultures. Total RNA was harvested and hybridized to miRIDIAN miR arrays by Dharmacon. Original magnification, ×20. (C and D) Venn diagrams depicting miRs induced by TGF-β in 67NR, 4T07, and 4T1 cells revealed that the miR-181 family was upregulated by TGF-β1 treatment in all breast cancer cell lines and treatment conditions. mmu, Mus musculus. (E and F) TGF-β1 (5 ng/ml) treatment of 67NR, 4T07, and 4T1 cells propagated in either rigid (3 mg/ml collagen, E) or compliant (F) 3D organotypic cultures increased miR-181a expression in a manner correlated with the metastatic potential of individual breast cancer cell lines. (G and H) TGF-β1 (5 ng/ml) treatment of mouse 67NR, 4T07, and 4T1 (G), and of human MCF-7 and MDA-MB-231 (H) cells propagated in traditional 2D cultures stimulated miR-181a expression in a manner correlated with the metastatic potential of the individual cell lines. Individual miR signals were normalized to U6, and the data are presented as the mean ± SEM fold expression of miR-181a relative to basal 67NR or MCF-7 cells. n = 3. *P < 0.05, Student’s t test.