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Abstract Transforming growth factor (TGF)‐β1 is a multifunctional cytokine that plays important roles in health and disease. Previous studies have revealed that TGFβ1 activation, signaling, and downstream cell responses including epithelial‐mesenchymal transition (EMT) and apoptosis are regulated by the elasticity or stiffness of the extracellular matrix. However, tissues within the body are not purely elastic, rather they are viscoelastic. How matrix viscoelasticity impacts cell fate decisions downstream of TGFβ1 remains unknown. Here, we synthesized polyacrylamide hydrogels that mimic the viscoelastic properties of breast tumor tissue. We found that increasing matrix viscous dissipation reduces TGFβ1‐induced cell spreading, F‐actin stress fiber formation, and EMT‐associated gene expression changes, and promotes TGFβ1‐induced apoptosis in mammary epithelial cells. Furthermore, TGFβ1‐induced expression of integrin linked kinase (ILK) and colocalization of ILK with vinculin at cell adhesions is attenuated in mammary epithelial cells cultured on viscoelastic substrata in comparison to cells cultured on nearly elastic substrata. Overexpression of ILK promotes TGFβ1‐induced EMT and reduces apoptosis in cells cultured on viscoelastic substrata, suggesting that ILK plays an important role in regulating cell fate downstream of TGFβ1 in response to matrix viscoelasticity.
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Removal of Serum Lipids and Lipid‐Derived Metabolites to Investigate Breast Cancer Cell Biology
Abstract The use of cultured cells has been instrumental in studying biochemical, molecular, and cellular processes. The composition of serum that cells are maintained in can have a profound impact on important cellular checkpoints. Cell growth and apoptosis are analyzed in an estrogen receptor positive breast cancer cell line in the presence of serum that have been treated to remove steroids or lipids, as well‐described in the literature. It is shown that maintaining cells in the presence of charcoal‐dextran‐treated serum causes reduced growth rate, which can be reversed by the addition of estradiol. Silica‐treated‐serum also slows down cell growth and induces apoptosis. In order to investigate the role of lipids in these phenotypes, the levels of a wide range of lipids in different sera are investigated. It is shown that silica‐treatment significantly depletes phosphatidylcholines and cholesterol. It is also shown that lipogenesis is stimulated when cells are cultured with silica‐treated‐serum and this is reversed by the addition of exogenous lipids, which also restores growth rate and apoptosis. The results show that cultured cells are sensitive to different serum, most likely due to the differences in levels of structural and signaling metabolites present in their growth environment.
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- Award ID(s):
- 1817468
- PAR ID:
- 10460706
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- PROTEOMICS
- Volume:
- 19
- Issue:
- 18
- ISSN:
- 1615-9853
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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