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 March 1, 2013; First 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 1

Chemotherapy-treated breast cancers display increased markers of TGF-β signaling and CSCs.

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Chemotherapy-treated breast cancers display increased markers of TGF-β s...
(A) NanoString analysis of TGF-β pathway genes in RNA extracted from breast cancer biopsies before chemotherapy (Pre-Tx) and after chemotherapy (Post-Tx). A TGF-β gene expression score was generated in both groups, as described in Methods (n = 17; paired Student’s t test, P = 0.002). (B) Box plots of TGFBR2, TGFBR3, and SMAD4 gene expression between biopsies before and after chemotherapy (TGFBR2: P = 0.007, TGFBR3: P = 0.0026, SMAD4: P = 0.012). Symbols indicate individual tumors; horizontal bars represent the mean. (C) Box plots of gene expression of CSC genes CD44 and ALDH1A1 (CD44: P = 0.013; ALDH1A1: P = 0.0067). (D) Box plots of FOS, JUNB, JUN, CDKN1A gene expression in the 17 paired tumors (paired Student’s t test, P < 0.0008 for all 4 comparisons). (B–D) In box-and-whisker plots, horizontal bars indicate the medians, boxes indicate 25th to 75th percentiles, and whiskers indicate 10th and 90th percentiles. (E) TGFB1 and TGFBR2 mRNA from SUM159 cells treated with or without 10 nM paclitaxel for 6 days was measured by quantitative RT-PCR (*P = 0.03). Using the TGF-β–specific PCR array described in Methods, the expression of JUNB, JUN, FOS, and CDKN1A were assessed and quantified in both control (C) and paclitaxel-treated (P) cells. Error bars indicate SEM.