TGF-β inhibition enhances chemotherapy action against triple-negative breast cancer
Neil E. Bhola, … , Rebecca S. Cook, Carlos L. Arteaga
Neil E. Bhola, … , Rebecca S. Cook, Carlos L. Arteaga
Published February 8, 2013
Citation Information: J Clin Invest. 2013;123(3):1348-1358. https://doi.org/10.1172/JCI65416.
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Research Article Oncology

TGF-β inhibition enhances chemotherapy action against triple-negative breast cancer

Abstract

After an initial response to chemotherapy, many patients with triple-negative breast cancer (TNBC) have recurrence of drug-resistant metastatic disease. Studies with TNBC cells suggest that chemotherapy-resistant populations of cancer stem-like cells (CSCs) with self-renewing and tumor-initiating capacities are responsible for these relapses. TGF-β has been shown to increase stem-like properties in human breast cancer cells. We analyzed RNA expression in matched pairs of primary breast cancer biopsies before and after chemotherapy. Biopsies after chemotherapy displayed increased RNA transcripts of genes associated with CSCs and TGF-β signaling. In TNBC cell lines and mouse xenografts, the chemotherapeutic drug paclitaxel increased autocrine TGF-β signaling and IL-8 expression and enriched for CSCs, as indicated by mammosphere formation and CSC markers. The TGF-β type I receptor kinase inhibitor LY2157299, a neutralizing TGF-β type II receptor antibody, and SMAD4 siRNA all blocked paclitaxel-induced IL8 transcription and CSC expansion. Moreover, treatment of TNBC xenografts with LY2157299 prevented reestablishment of tumors after paclitaxel treatment. These data suggest that chemotherapy-induced TGF-β signaling enhances tumor recurrence through IL-8–dependent expansion of CSCs and that TGF-β pathway inhibitors prevent the development of drug-resistant CSCs. These findings support testing a combination of TGF-β inhibitors and anticancer chemotherapy in patients with TNBC.

Authors

Neil E. Bhola, Justin M. Balko, Teresa C. Dugger, María Gabriela Kuba, Violeta Sánchez, Melinda Sanders, Jamie Stanford, Rebecca S. Cook, Carlos L. Arteaga

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Figure 2

Paclitaxel enriches a CSC population with increased TGF-β signaling.

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Paclitaxel enriches a CSC population with increased TGF-β signaling. (A ...
(A and B) SUM159 and BT549 cells were treated with vehicle (control) or 10 nM paclitaxel for 4 days and allowed to recover in fresh media for another 4 days. Cells were trypsinized and analyzed by FACS for (A) ALDH activity and CD44hi/PROCR+ expression (*P < 0.01) or (B) assessed for their ability to form mammospheres (*P = 0.04). (C) SUM159 xenografts were treated with vehicle or 10 and 20 mg/kg/d paclitaxel for 5 consecutive days (treatment started at day 1 and ended at day 6 of x axis). Tumor diameters were measured every 3 days using calipers, and volume in mm3 was calculated as described in Methods. Xenografts were harvested on day 15, dissociated into single cells, and grown as mammospheres. Each bar represents the mean mammosphere number ± SEM (n = 3; *P < 0.05). Original magnification, ×100. (D) Whole lysates from the same SUM159 xenografts as in C were subjected to P-SMAD2, total SMAD2/3, and actin (control) immunoblot analysis. exp, exposure. (E) SUM159 and BT549 cells were treated with vehicle or 5 nM or 10 nM paclitaxel for 4 days and seeded in 24-well plates. Cells were transfected with pCAGA-Luc and Renilla plasmids; luciferase activity was determined 24 hours later using the Dual Luciferase Kit, as described in Methods (n = 3; *P < 0.05). Error bars indicate SEM.