Figure 7.

The role of EGFR in MCF-7 and MDA-MB-231 cells in COL1 induced cell activation affected by integrin β₁-knockdown (ITGB1-kd). (a) Data of a surface receptor proteome profiler array indicate that the knockdown of ITGB1 (green) in MDA-MB 231 and MCF-7 cells was antagonized by the upregulation of integrin β₄ (ITGB4, red) compared to wildtype (wt). (b) Western blot of ITGB4 in MCF-7 and MDA-MB-231 scrambled (sc) cells in dependence of collagen type 1 (COL1) or ITGB1-status (n = 3 biological samples). GAPDH was used as loading control. Data indicate that ITGB1-kd is associated with the upregulation of ITGB4. ITGB4 can form an active crosstalk to activate (c) pEGFR in MDA-MB-231kd, but only slightly in MCF-7kd cells (n = 3 biological samples). (d,e) Blocking of pEGFR by gefitinib was highly synergistic with ERK1/2-inhibition in MDA-MB-231 cells indicating a key role of EGFR in COL1-induced activation of MDA-MB-231 cells (n = at least 3 biological samples). Statistical analysis was performed via unpaired t-test (* p < 0.05; ** p < 0.01).