Progression of Luminal Breast Tumors Is Promoted by Ménage à Trois between the Inflammatory Cytokine TNFα and the Hormonal and Growth-Supporting Arms of the Tumor Microenvironment

Figure 4

Combined stimulation of breast tumor cells by TNFα + Estrogen + EGF leads to increased expression of the β1 integrin and to emergence of high-VLA6 cell population (α6β1^high). ((a), (B)) Determination of β1 expression. Breast tumor cells were stimulated by (a1) TNFα, (a2) estrogen, (a3) EGF, or (B) TNFα + Estrogen + EGF (concentrations as in Figure 1) for three days. Non-stimulated: cells grown with the diluents of the above factors. The expression of β1 on the surface of the cells was determined by FACS analyses, using specific Abs. Isotype: isotype matched Abs used as control in the FACS analyses. In all panels, the results are from a representative experiment of 𝑛≥3. (c) Coexpression of the β1 and α6 integrin subunits. (c1) Non-stimulated: cells grown with the diluents of the above factors. (c2) Cells stimulated by TNFα + Estrogen + EGF (concentrations as in Figure 1). The expression of β1 and of α6 on the surface of the cells was determined by FACS analyses using specific Abs, with axes set based on staining with isotype matched control Abs. In all panels, the results are from a representative experiment of 𝑛≥3.