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Highlights from the latest articles in regenerative medicine
Triggering the switch from benign to malignant phenotypes in vitro through independent modulation of extracellular matrix stiffness and composition Evaluation of: Chaudhuri O, Koshy ST, Branco da Cunha C et al. Extracellular matrix stiffness and composition jointly regulate the induction of malignant phenotypes in mammary epithelium. Nat. Mater. doi:10.1038/nmat4009 (2014) (Epub ahead of print).
Although tumorigenesis and cancer progression have long been associated with an altered tumor microenvironment, establishing the physical, chemical and biological factors that influence the hallmarks of cancer, including invasiveness and metastasis, remains a major challenge for tissue engineers and biologists alike. Breast cancer detection relies on determining the physical changes in stiffness and density of mammary tissues. However, the functional significance of those changes is unknown. In this study, Chaudhuri et al. describe a carefully regulated 3D culture system where matrix stiffness can be altered independently of extracellular matrix (ECM) composition and architecture [1] . Interpenetrating networks (IPNs) of alginate and the reconstituted basement membrane (rBM) matrigel were formed to probe the conditions that trigger malignant phenotypes in the mammary epithelium [2–5] . Alginate stiffness and crosslinking was modulated through divalent Ca 2+ cations without altering the polymer composition, and the IPNs exhibited equivalent pore structure and size as well as diffusion characteristics across a range of Young’s moduli indicative of both normal and malignant
10.2217/RME.14.70 © 2014 Future Medicine Ltd
breast tissue stiffness. Using MCF10A nonmalignant mammary epithelial cells, the authors show that an independent increase in IPN stiffness leads to a malignant cellular phenotype. Surprisingly, altered stiffness alone was not sufficient to generate a malignant phenotype: cells grown in rBM matrix alone did not become malignant despite an increase in stiffness. Moreover, adding RGD binding motifs to the alginate gel restored the malignant phenotype. Invasiveness increased with higher RGD concentration and thus higher adhesion-ligand density while stiffness remained constant. Components of the laminin-rich rBM matrix bind to the α6β4 integrin while RGD binds through αv and β1 integrins. This suggests that malignant transitioning requires specific receptor–ligand interactions. The authors propose a mechanism where malignant behavior is mediated through reduced clustering of α6β4 integrins upon sensing increased ECM stiffness whereas an increase in basement membrane ligand density can restore clustering and prevent the malignant phenotype at higher stiffness. In addition, it was shown that the malignant phenotype is regulated through the Rac1 and PI3K molecular pathway, which influences cell proliferation and migration. This is the first study that has successfully decoupled the conditions for stiffness and ECM composition that incite a benign to malignant switch in an in vitro mammary epithelium model. The findings here point to the importance of evaluating not only microenvironmental stiffness and density but also ECM composition during breast cancer detection, which could guide cancer prevention strategies or potential therapeutic opportunities. In addition to the application
Regen. Med. (2014) 9(6), 721–722
Marjan Rafat Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA [email protected]
part of
ISSN 1746-0751
721
Research Highlights Rafat presented in this paper, the concept of independently tuning modulus and composition could be particularly useful in regulating stem cell differentiation cues or in fabricating tissue engineering scaffolds for wound healing. While this work represents a major advance in designing 3D culture systems, validation of this phenomenon in patient tissues will be necessary to establish how ECM composition and stiffness jointly relate to cancer development and progression in the clinic.
Financial & competing interests disclosure
References
3
Weaver VM, Petersen OW, Wang F et al. Reversion of the malignant phenotype of human breast cells in threedimensional culture and in vivo by integrin blocking antibodies. J. Cell Biol. 137(1), 231–245 (1997).
4
Paszek MJ, Zahir N, Johnson KR et al. Tensional homeostasis and the malignant phenotype. Cancer Cell 8(3), 241–254 (2005).
5
Debnath J, Brugge JS. Modelling glandular epithelial cancers in three-dimensional cultures. Nat. Rev. Cancer 5(9), 675–688 (2005).
1
2
722
Chaudhuri O, Koshy ST, Branco da Cunha C et al. Extracellular matrix stiffness and composition jointly regulate the induction of malignant phenotypes in mammary epithelium. Nat. Mater. doi:10.1038/nmat4009 (2014) (Epub ahead of print). Petersen OW, Rønnov-Jessen L, Howlett AR, Bissell MJ. Interaction with basement membrane serves to rapidly distinguish growth and differentiation pattern of normal and malignant human breast epithelial cells. Proc. Natl Acad. Sci. USA 89(19), 9064–9068 (1992).
Regen. Med. (2014) 9(6)
The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.
future science group
Highlights from the latest articles in regenerative medicine
Triggering the switch from benign to malignant phenotypes in vitro through independent modulation of extracellular matrix stiffness and composition Evaluation of: Chaudhuri O, Koshy ST, Branco da Cunha C et al. Extracellular matrix stiffness and composition jointly regulate the induction of malignant phenotypes in mammary epithelium. Nat. Mater. doi:10.1038/nmat4009 (2014) (Epub ahead of print).
Although tumorigenesis and cancer progression have long been associated with an altered tumor microenvironment, establishing the physical, chemical and biological factors that influence the hallmarks of cancer, including invasiveness and metastasis, remains a major challenge for tissue engineers and biologists alike. Breast cancer detection relies on determining the physical changes in stiffness and density of mammary tissues. However, the functional significance of those changes is unknown. In this study, Chaudhuri et al. describe a carefully regulated 3D culture system where matrix stiffness can be altered independently of extracellular matrix (ECM) composition and architecture [1] . Interpenetrating networks (IPNs) of alginate and the reconstituted basement membrane (rBM) matrigel were formed to probe the conditions that trigger malignant phenotypes in the mammary epithelium [2–5] . Alginate stiffness and crosslinking was modulated through divalent Ca 2+ cations without altering the polymer composition, and the IPNs exhibited equivalent pore structure and size as well as diffusion characteristics across a range of Young’s moduli indicative of both normal and malignant
10.2217/RME.14.70 © 2014 Future Medicine Ltd
breast tissue stiffness. Using MCF10A nonmalignant mammary epithelial cells, the authors show that an independent increase in IPN stiffness leads to a malignant cellular phenotype. Surprisingly, altered stiffness alone was not sufficient to generate a malignant phenotype: cells grown in rBM matrix alone did not become malignant despite an increase in stiffness. Moreover, adding RGD binding motifs to the alginate gel restored the malignant phenotype. Invasiveness increased with higher RGD concentration and thus higher adhesion-ligand density while stiffness remained constant. Components of the laminin-rich rBM matrix bind to the α6β4 integrin while RGD binds through αv and β1 integrins. This suggests that malignant transitioning requires specific receptor–ligand interactions. The authors propose a mechanism where malignant behavior is mediated through reduced clustering of α6β4 integrins upon sensing increased ECM stiffness whereas an increase in basement membrane ligand density can restore clustering and prevent the malignant phenotype at higher stiffness. In addition, it was shown that the malignant phenotype is regulated through the Rac1 and PI3K molecular pathway, which influences cell proliferation and migration. This is the first study that has successfully decoupled the conditions for stiffness and ECM composition that incite a benign to malignant switch in an in vitro mammary epithelium model. The findings here point to the importance of evaluating not only microenvironmental stiffness and density but also ECM composition during breast cancer detection, which could guide cancer prevention strategies or potential therapeutic opportunities. In addition to the application
Regen. Med. (2014) 9(6), 721–722
Marjan Rafat Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA [email protected]
part of
ISSN 1746-0751
721
Research Highlights Rafat presented in this paper, the concept of independently tuning modulus and composition could be particularly useful in regulating stem cell differentiation cues or in fabricating tissue engineering scaffolds for wound healing. While this work represents a major advance in designing 3D culture systems, validation of this phenomenon in patient tissues will be necessary to establish how ECM composition and stiffness jointly relate to cancer development and progression in the clinic.
Financial & competing interests disclosure
References
3
Weaver VM, Petersen OW, Wang F et al. Reversion of the malignant phenotype of human breast cells in threedimensional culture and in vivo by integrin blocking antibodies. J. Cell Biol. 137(1), 231–245 (1997).
4
Paszek MJ, Zahir N, Johnson KR et al. Tensional homeostasis and the malignant phenotype. Cancer Cell 8(3), 241–254 (2005).
5
Debnath J, Brugge JS. Modelling glandular epithelial cancers in three-dimensional cultures. Nat. Rev. Cancer 5(9), 675–688 (2005).
1
2
722
Chaudhuri O, Koshy ST, Branco da Cunha C et al. Extracellular matrix stiffness and composition jointly regulate the induction of malignant phenotypes in mammary epithelium. Nat. Mater. doi:10.1038/nmat4009 (2014) (Epub ahead of print). Petersen OW, Rønnov-Jessen L, Howlett AR, Bissell MJ. Interaction with basement membrane serves to rapidly distinguish growth and differentiation pattern of normal and malignant human breast epithelial cells. Proc. Natl Acad. Sci. USA 89(19), 9064–9068 (1992).
Regen. Med. (2014) 9(6)
The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.
future science group
