Cited by 437Hedgehog Signaling Pathway StudiesCancer Cells and MetastasisBreast Cancer Treatment Studies

Targeting stromal remodeling and cancer stem cell plasticity overcomes chemoresistance in triple negative breast cancer

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Cazet, Aurélie S., Hui, Mun N., Elsworth, Benjamin L., Wu, Sunny Z., Roden, Daniel, Chan, Chia-Ling, Skhinas, Joanna N., Collot, Raphaël +21 more·2018·Nature Communications

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Abstract

ABSTRACT The cellular and molecular basis of stromal cell recruitment, activation and crosstalk in carcinomas is poorly understood, limiting the development of targeted anti-stromal therapies. In mouse models of triple negative breast cancer (TNBC), Hh ligand produced by neoplastic cells reprogrammed cancer-associated fibroblast (CAF) gene expression, driving tumor growth and metastasis. Hh-activated CAFs upregulated expression of FGF5 and production of fibrillar collagen, leading to FGFR and FAK activation in adjacent neoplastic cells, which then acquired a stem-like, drug-resistant phenotype. Treatment with smoothened inhibitors (SMOi) reversed these phenotypes. Stromal treatment of TNBC patient-derived xenograft (PDX) models with SMOi downregulated the expression of cancer stem cell markers and sensitized tumors to docetaxel, leading to markedly improved survival and reduced metastatic burden. In the phase I clinical trial EDALINE, 3 of 12 patients with metastatic TNBC derived clinical benefit from combination therapy with the SMOi Sonidegib and docetaxel chemotherapy, with one patient experiencing a complete response. Markers of pathway activity correlated with response. These studies identify Hh signaling to CAFs as a novel mediator of cancer stem cell plasticity and an exciting new therapeutic target in TNBC. SIGNIFICANCE Compared to other breast cancer subtypes, TNBCs are associated with significantly worse patient outcomes. Standard of care systemic treatment for patients with non-BRCA1/2 positive TNBC is cytotoxic chemotherapy. However, the failure of 70% of treated TNBCs to attain complete pathological response reflects the relative chemoresistance of these tumors. New therapeutic strategies are needed to improve patient survival and quality of life. Here, we provide new insights into the dynamic interactions between heterotypic cells within a tumor. Specifically, we establish the mechanisms by which CAFs define cancer cell phenotype and demonstrate that the bidirectional CAF-cancer cell crosstalk can be successfully targeted in mice and humans using anti-stromal therapy.

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  • Production of TGFβ, LIF, GAS6, FGF5, GDF15 and HGF promotes invasive and proliferative behaviour in cancer cells.

    “The production of TGFβ, leukaemia inhibitory factor (LIF), growth arrest-specific protein 6 (GAS6), fibroblast growth factor 5 (FGF5), growth differentiation factor 15 (GDF15) and hepatocyte growth factor (HGF) promotes invasive and proliferative behaviour in cancer cells52,109–112.”

    From A framework for advancing our understanding of cancer-associated fibroblasts (2020) · cites this paper as [110]

    The Results section on the paracrine Hh–FGF5 axis (page unavailable) reports that FGF5 produced by activated stromal cells increased proliferation of M6 breast cancer cells under serum and growth-factor deprivation. It does not establish that FGF5 promotes invasion or support the listed effects of TGFβ, LIF, GAS6, GDF15, and HGF. (LLM, conf=0.86)

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  1. [1]Perrimon N Pitsouli C Shilo BZ Signaling mechanisms controlling cell fate and embryonic patterning Cold Spring Harb. Perspect. Biol. 2012 4 a005975 10.1101/cshperspect.a005975 22855721 PMC3405863 · DOI
  2. [2]Wiseman BS Werb Z Stromal effects on mammary gland development and breast cancer Science 2002 296 1046 1049 10.1126/science.1067431 12004111 PMC2788989 · DOI
  3. [3]Chuang PT Kawcak T McMahon AP Feedback control of mammalian Hedgehog signaling by the Hedgehog-binding protein, Hip1, modulates Fgf signaling during branching morphogenesis of the lung Genes Dev. 2003 17 342 347 10.1101/gad.1026303 12569124 PMC195990 · DOI
  4. [4]Hui M The Hedgehog signalling pathway in breast development, carcinogenesis and cancer therapy Breast Cancer Res. 2013 15 203 10.1186/bcr3401 23547970 PMC3672663 · DOI
  5. [5]Amakye D Jagani Z Dorsch M Unraveling the therapeutic potential of the Hedgehog pathway in cancer Nat. Med. 2013 19 1410 1422 10.1038/nm.3389 24202394 · DOI
  6. [6]O’Toole SA Hedgehog overexpression is associated with stromal interactions and predicts for poor outcome in breast cancer Cancer Res. 2011 71 4002 4014 10.1158/0008-5472.CAN-10-3738 21632555 · DOI
  7. [7]Hanahan D Weinberg RA Hallmarks of cancer: the next generation Cell 2011 144 646 674 10.1016/j.cell.2011.02.013 21376230 · DOI · Paper page
  8. [8]Levental KR Matrix crosslinking forces tumor progression by enhancing integrin signaling Cell 2009 139 891 906 10.1016/j.cell.2009.10.027 19931152 PMC2788004 · DOI · Paper page
  9. [9]Laklai H Genotype tunes pancreatic ductal adenocarcinoma tissue tension to induce matricellular fibrosis and tumor progression Nat. Med. 2016 22 497 505 10.1038/nm.4082 27089513 PMC4860133 · DOI
  10. [10]Finak G Stromal gene expression predicts clinical outcome in breast cancer Nat. Med. 2008 14 518 527 10.1038/nm1764 18438415 · DOI
  11. [11]Farmer P A stroma-related gene signature predicts resistance to neoadjuvant chemotherapy in breast cancer Nat. Med. 2009 15 68 74 10.1038/nm.1908 19122658 · DOI
  12. [12]Valenti G Cancer stem cells regulate cancer-associated fibroblasts via activation of Hedgehog signaling in mammary gland tumors Cancer Res. 2017 77 2134 2147 10.1158/0008-5472.CAN-15-3490 28202523 · DOI
  13. [13]Heller E Hedgehog signaling inhibition blocks growth of resistant tumors through effects on tumor microenvironment Cancer Res. 2012 72 897 907 10.1158/0008-5472.CAN-11-2681 22186138 PMC3659806 · DOI
  14. [15]Vaillant F The mammary progenitor marker CD61/beta3 integrin identifies cancer stem cells in mouse models of mammary tumorigenesis Cancer Res. 2008 68 7711 7717 10.1158/0008-5472.CAN-08-1949 18829523 · DOI
  15. [16]Hu Y Smyth GK ELDA: extreme limiting dilution analysis for comparing depleted and enriched populations in stem cell and other assays J Immunol Methods 2009 347 70 78 10.1016/j.jim.2009.06.008 19567251 · DOI
  16. [17]Bu W Keratin 6a marks mammary bipotential progenitor cells that can give rise to a unique tumor model resembling human normal-like breast cancer Oncogene 2011 30 4399 4409 10.1038/onc.2011.147 21532625 PMC3156856 · DOI
  17. [20]Peiris-Pages M Sotgia F Lisanti MP Chemotherapy induces the cancer-associated fibroblast phenotype, activating paracrine Hedgehog-GLI signalling in breast cancer cells Oncotarget 2015 6 10728 10745 10.18632/oncotarget.3828 25915429 PMC4484415 · DOI · Paper page
  18. [21]Huo CW High mammographic density is associated with an increase in stromal collagen and immune cells within the mammary epithelium Breast Cancer Res. 2015 17 79 10.1186/s13058-015-0592-1 26040322 PMC4485361 · DOI
  19. [22]Keikhosravi A Bredfeldt JS Sagar AK Eliceiri KW Second-harmonic generation imaging of cancer Methods Cell Biol. 2014 123 531 546 10.1016/B978-0-12-420138-5.00028-8 24974046 · DOI
  20. [23]Mayorca-Guiliani AE ISDoT: in situ decellularization of tissues for high-resolution imaging and proteomic analysis of native extracellular matrix Nat. Med. 2017 23 890 898 10.1038/nm.4352 28604702 · DOI
  21. [24]Cicchi R Scoring of collagen organization in healthy and diseased human dermis by multiphoton microscopy J. Biophotonics 2010 3 34 43 10.1002/jbio.200910062 19771581 · DOI
  22. [25]Rowley JA Madlambayan G Mooney DJ Alginate hydrogels as synthetic extracellular matrix materials Biomaterials 1999 20 45 53 10.1016/S0142-9612(98)00107-0 9916770 · DOI · Paper page
  23. [26]Branco da Cunha C Influence of the stiffness of three-dimensional alginate/collagen-I interpenetrating networks on fibroblast biology Biomaterials 2014 35 8927 8936 10.1016/j.biomaterials.2014.06.047 25047628 · DOI
  24. [27]Chaudhuri O Extracellular matrix stiffness and composition jointly regulate the induction of malignant phenotypes in mammary epithelium Nat. Mater. 2014 13 970 978 10.1038/nmat4009 24930031 · DOI · Paper page
  25. [28]O’Reilly EA The fate of chemoresistance in triple negative breast cancer (TNBC) BBA Clin. 2015 3 257 275 10.1016/j.bbacli.2015.03.003 26676166 PMC4661576 · DOI
  26. [29]DeRose YS Tumor grafts derived from women with breast cancer authentically reflect tumor pathology, growth, metastasis and disease outcomes Nat. Med. 2011 17 1514 1520 10.1038/nm.2454 22019887 PMC3553601 · DOI
  27. [30]Volk-Draper L Paclitaxel therapy promotes breast cancer metastasis in a TLR4-dependent manner Cancer Res. 2014 74 5421 5434 10.1158/0008-5472.CAN-14-0067 25274031 PMC4185415 · DOI
  28. [32]Malanchi I Interactions between cancer stem cells and their niche govern metastatic colonization Nature 2011 481 85 89 10.1038/nature10694 22158103 · DOI · Paper page
  29. [33]Lawson DA Single-cell analysis reveals a stem-cell program in human metastatic breast cancer cells Nature 2015 526 131 135 10.1038/nature15260 26416748 PMC4648562 · DOI
  30. [34]Pang R A subpopulation of CD26+cancer stem cells with metastatic capacity in human colorectal cancer Cell Stem Cell 2010 6 603 615 10.1016/j.stem.2010.04.001 20569697 · DOI
  31. [35]Chen J A restricted cell population propagates glioblastoma growth after chemotherapy Nature 2012 488 522 526 10.1038/nature11287 22854781 PMC3427400 · DOI · Paper page
  32. [36]Li X Intrinsic resistance of tumorigenic breast cancer cells to chemotherapy J. Natl. Cancer Inst. 2008 100 672 679 10.1093/jnci/djn123 18445819 · DOI
  33. [37]Yu F let-7 regulates self renewal and tumorigenicity of breast cancer cells Cell 2007 131 1109 1123 10.1016/j.cell.2007.10.054 18083101 · DOI
  34. [38]Meacham CE Morrison SJ Tumour heterogeneity and cancer cell plasticity Nature 2013 501 328 337 10.1038/nature12624 24048065 PMC4521623 · DOI
  35. [39]Mani SA The epithelial-mesenchymal transition generates cells with properties of stem cells Cell 2008 133 704 715 10.1016/j.cell.2008.03.027 18485877 PMC2728032 · DOI
  36. [40]Chaffer CL Poised chromatin at the ZEB1 promoter enables breast cancer cell plasticity and enhances tumorigenicity Cell 2013 154 61 74 10.1016/j.cell.2013.06.005 23827675 PMC4015106 · DOI
  37. [41]Samuel MS Actomyosin-mediated cellular tension drives increased tissue stiffness and beta-catenin activation to induce epidermal hyperplasia and tumor growth Cancer Cell. 2011 19 776 791 10.1016/j.ccr.2011.05.008 21665151 PMC3115541 · DOI
  38. [42]Ibbetson SJ Pyne NT Pollard AN Olson MF Samuel MS Mechanotransduction pathways promoting tumor progression are activated in invasive human squamous cell carcinoma Am. J. Pathol. 2013 183 930 937 10.1016/j.ajpath.2013.05.014 23830873 · DOI
  39. [43]Pang MF Tissue stiffness and hypoxia modulate the integrin-linked kinase ILK to control breast cancer stem-like cells Cancer Res. 2016 76 5277 5287 10.1158/0008-5472.CAN-16-0579 27503933 PMC5026611 · DOI
  40. [44]Sherratt MJ McConnell JC Streuli CH Raised mammographic density: causative mechanisms and biological consequences Breast Cancer Res. 2016 18 45 10.1186/s13058-016-0701-9 27142210 PMC4855337 · DOI
  41. [45]McConnell JC Increased peri-ductal collagen micro-organization may contribute to raised mammographic density Breast Cancer Res. 2016 18 5 10.1186/s13058-015-0664-2 26747277 PMC4706673 · DOI · Paper page
  42. [46]Alvero AB Stem-like ovarian cancer cells can serve as tumor vascular progenitors Stem Cells 2009 27 2405 2413 10.1002/stem.191 19658191 PMC2783765 · DOI
  43. [47]Spike BT A mammary stem cell population identified and characterized in late embryogenesis reveals similarities to human breast cancer Cell Stem Cell 2012 10 183 197 10.1016/j.stem.2011.12.018 22305568 PMC3277444 · DOI
  44. [48]Dravis C Sox10 regulates stem/progenitor and mesenchymal cell states in mammary epithelial cells Cell Rep. 2015 12 2035 2048 10.1016/j.celrep.2015.08.040 26365194 PMC4591253 · DOI
  45. [49]Fillmore CM Estrogen expands breast cancer stem-like cells through paracrine FGF/Tbx3 signaling Proc. Natl. Acad. Sci. USA 2010 107 21737 21742 10.1073/pnas.1007863107 21098263 PMC3003123 · DOI
  46. [50]Su SC CD10(+) GPR77(+) cancer-associated fibroblasts promote cancer formation and chemoresistance by sustaining cancer stemness Cell 2018 172 841-+ 10.1016/j.cell.2018.01.009 29395328 · DOI · Paper page
  47. [51]Babina IS Turner NC Advances and challenges in targeting FGFR signalling in cancer Nat. Rev. Cancer 2017 17 318 332 10.1038/nrc.2017.8 28303906 · DOI
  48. [52]Wilkinson SE Hedgehog signaling is active in human prostate cancer stroma and regulates proliferation and differentiation of adjacent epithelium Prostate 2013 73 1810 1823 10.1002/pros.22720 24105601 · DOI
  49. [53]Lasorella A Benezra R Iavarone A The ID proteins: master regulators of cancer stem cells and tumour aggressiveness Nat. Rev. Cancer 2014 14 77 91 10.1038/nrc3638 24442143 · DOI
  50. [54]Bain G Regulation of the helix-loop-helix proteins, E2A and Id3, by the Ras-ERK MAPK cascade Nat. Immunol. 2001 2 165 171 10.1038/84273 11175815 · DOI
  51. [55]Wilgus TA Growth factor-extracellular matrix interactions regulate wound repair Adv. Wound Care (New Rochelle) 2012 1 249 254 10.1089/wound.2011.0344 24527314 PMC3623585 · DOI
  52. [56]Kouros-Mehr H Werb Z Candidate regulators of mammary branching morphogenesis identified by genome-wide transcript analysis Dev. Dyn. 2006 235 3404 3412 10.1002/dvdy.20978 17039550 PMC2730892 · DOI
  53. [57]Lewis MT The Gli2 transcription factor is required for normal mouse mammary gland development Dev. Biol. 2001 238 133 144 10.1006/dbio.2001.0410 11783999 · DOI
  54. [58]Lu P Ewald AJ Martin GR Werb Z Genetic mosaic analysis reveals FGF receptor 2 function in terminal end buds during mammary gland branching morphogenesis Dev. Biol. 2008 321 77 87 10.1016/j.ydbio.2008.06.005 18585375 PMC2582391 · DOI
  55. [59]Pond AC Fibroblast growth factor receptor signaling is essential for normal mammary gland development and stem cell function Stem Cells 2013 31 178 189 10.1002/stem.1266 23097355 PMC3690809 · DOI
  56. [60]Luhr I Mammary fibroblasts regulate morphogenesis of normal and tumorigenic breast epithelial cells by mechanical and paracrine signals Cancer Lett. 2012 325 175 188 10.1016/j.canlet.2012.06.014 22776560 PMC3708601 · DOI
  57. [61]Rhim AD Stromal elements act to restrain, rather than support, pancreatic ductal adenocarcinoma Cancer Cell. 2014 25 735 747 10.1016/j.ccr.2014.04.021 24856585 PMC4096698 · DOI · Paper page
  58. [62]Shin K Hedgehog signaling restrains bladder cancer progression by eliciting stromal production of urothelial differentiation factors Cancer Cell. 2014 26 521 533 10.1016/j.ccell.2014.09.001 25314078 PMC4326077 · DOI
  59. [63]Gerling M Stromal Hedgehog signalling is downregulated in colon cancer and its restoration restrains tumour growth Nat. Commun. 2016 7 12321 10.1038/ncomms12321 27492255 PMC4980446 · DOI
  60. [65]Chen WJ Cancer-associated fibroblasts regulate the plasticity of lung cancer stemness via paracrine signalling Nat. Commun. 2014 5 3472 10.1038/ncomms4472 24668028 · DOI
  61. [66]Hirata E Intravital imaging reveals how BRAF inhibition generates drug-tolerant microenvironments with high integrin beta1/FAK signaling Cancer Cell. 2015 27 574 588 10.1016/j.ccell.2015.03.008 25873177 PMC4402404 · DOI · Paper page
  62. [67]Lotti F Chemotherapy activates cancer-associated fibroblasts to maintain colorectal cancer-initiating cells by IL-17A J. Exp. Med. 2013 210 2851 2872 10.1084/jem.20131195 24323355 PMC3865474 · DOI
  63. [68]Holzer RG Development and characterization of a progressive series of mammary adenocarcinoma cell lines derived from the C3(1)/SV40 Large T-antigen transgenic mouse model Breast Cancer Res. Treat. 2003 77 65 76 10.1023/A:1021175931177 12602905 · DOI
  64. [69]Risso D Ngai J Speed TP Dudoit S Normalization of RNA-seq data using factor analysis of control genes or samples Nat. Biotechnol. 2014 32 896 902 10.1038/nbt.2931 25150836 PMC4404308 · DOI · Paper page
  65. [70]Robinson MD McCarthy DJ Smyth GK edgeR: a Bioconductor package for differential expression analysis of digital gene expression data Bioinformatics 2010 26 139 140 10.1093/bioinformatics/btp616 19910308 PMC2796818 · DOI · Paper page
  66. [71]Macosko EZ Highly parallel genome-wide expression profiling of individual cells using nanoliter droplets Cell 2015 161 1202 1214 10.1016/j.cell.2015.05.002 26000488 PMC4481139 · DOI · Paper page
  67. [72]Gao J Integrative analysis of complex cancer genomics and clinical profiles using the cBioPortal Sci. Signal. 2013 6 pl1 10.1126/scisignal.2004088 23550210 PMC4160307 · DOI · Paper page
  68. [73]Schmittgen TD Livak KJ Analyzing real-time PCR data by the comparative C(T) method Nat. Protoc. 2008 3 1101 1108 10.1038/nprot.2008.73 18546601 · DOI · Paper page
  69. [74]Zhu AJ Scott MP Incredible journey: how do developmental signals travel through tissue? Genes Dev. 2004 18 2985 2997 10.1101/gad.1233104 15601817 · DOI
  70. [75]Marei H Differential Rac1 signalling by guanine nucleotide exchange factors implicates FLII in regulating Rac1-driven cell migration Nat. Commun. 2016 7 10664 10.1038/ncomms10664 26887924 PMC4759627 · DOI

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Authors
Cazet, A. S., Hui, M. N., Elsworth, B. L., Wu, S. Z., Roden, D., Chan, C.-L., Skhinas, J. N., Collot, R., Yang, J., Harvey, K., Johan, M. Z., Cooper, C., Nair, R., Herrmann, D., McFarland, A., Deng, N., Ruiz-Borrego, M., Rojo, F., Trigo, J. M., Bezares, S., Caballero, R., Lim, E., Timpson, P., O’Toole, S., Watkins, D. N., Cox, T. R., Samuel, M. S., Martín, M., & Swarbrick, A.
Affiliations
  • Garvan Institute of Medical Research (AU)
  • University of Bristol (GB)
  • South Australia Pathology (AU)
  • The University of Queensland (AU)
  • Rajiv Gandhi Centre for Biotechnology (IN)
  • Hospital Universitario Fundación Jiménez Díaz (ES)
  • Hospital Clínico Universitario Virgen de la Victoria (ES)
  • GEICAM – Spanish Breast Cancer Group (ES)
  • Instituto de Salud Carlos III (ES)
Corresponding author
Swarbrick, Alexander
Venue
Nature Communications
Published
2018-07-24
Volume
9
Issue
1
Pages
2897-2897
ISSN
2041-1723 (ISSN-L)
OpenAlex
W2949633340
Cited by
437
References
8
Citations by year
2026: 23 · 2025: 41 · 2024: 58 · 2023: 56 · 2022: 58 · 2021: 93 · 2020: 56 · 2019: 42 · 2018: 10
FWCI
18.05
Type
journal article
Language
en
Open access
Locations
  • Nature Communications (publishedVersion, cc-by)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Adelaide Research & Scholarship (AR&S) (University of Adelaide) (submittedVersion, cc-by)
  • UNSWorks (University of New South Wales, Sydney, Australia) (submittedVersion, cc-by-nc-nd)
  • Explore Bristol Research (submittedVersion, cc-by)
  • RISalud Institutional Health Repository of Andalucía (submittedVersion, cc-by)
  • UniSA Research Outputs Repository (University of South Australia) (submittedVersion, other-oa)
  • RePEc: Research Papers in Economics (submittedVersion)
  • LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) (submittedVersion, other-oa)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
  • Bristol Research (University of Bristol) (submittedVersion, cc-by)
Funders
  • Pfizer
  • Pfizer Australia
  • National Breast Cancer Foundation
  • Petre Foundation
  • Royal Adelaide Hospital
  • Medical Research Council
  • Australian Research Council
  • National Health and Medical Research Council
  • Cancer Council South Australia
  • Royal Adelaide Hospital Research Fund
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Hedgehog Signaling Pathway Studies
  • Health Sciences › Medicine › Oncology › Cancer Cells and Metastasis
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › Breast Cancer Treatment Studies
Keywords
triple-negative breast cancer, stromal remodeling, cancer-associated fibroblasts, Hedgehog signaling, cancer stem cells, chemoresistance, FGF5, Smoothened inhibitors, sonidegib, docetaxel, metastasis, patient-derived xenografts
MeSH terms
Docetaxel, Adult, Aged, Anilides, Animals, Antineoplastic Combined Chemotherapy Protocols, Biphenyl Compounds, Female, Humans, Middle Aged, Pyridines, Neoplastic Stem Cells, Mice, SCID, Mice, Inbred NOD, Treatment Outcome, Mice, Knockout, Drug Resistance, Neoplasm, Xenograft Model Antitumor Assays, Cell Line, Tumor, Triple Negative Breast Neoplasms

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