Figure 3

Tumor proliferation and epidermal growth factor receptor (EGFR) signaling are increased in mice co-injected with SUM149 cells and mesenchymal stem/stromal cells (MSCs). SUM149 cells (5 × 10⁵) were injected bilaterally into the cleared mammary fat pad of SCID/Beige mice with or without MSCs (10% of total number of cells injected per mammary gland). Tumors were resected in a survival surgery when tumors reached a volume of 300 mm³, fixed in formalin, embedded in paraffin, cut, stained and scored by a pathologist specialized in inflammatory breast cancer (IBC). (A) E-cadherin staining of tumor section from 0% MSC group. (B) E-cadherin staining of tumor section from 10% MSC group. (C) Quantification and comparison of E-cadherin staining between 0% and 10% MSC groups. E-cadherin staining was similar between 0% and 10% groups. P = NS, Student’s t test. (D) Ki-67 staining of tumor section from 0% MSC group. (E) Ki-67 staining of tumor section from 10% MSC group. (F) Quantification and comparison of Ki-67 staining between 0% and 10% MSC groups. Ki-67 staining from 10% MSC group was higher than in 0% MSC group (61.8% vs. 44.0%). ^*** P = 0.001, Student’s t test. (G) Phospho-EGFR (p-EGFR) staining of tumor section from 0% MSC group. (H) p-EGFR staining of tumor section from 10% MSC group. (I) Quantification and comparison of p-EGFR staining between 0% and 10% MSC groups. p-EGFR staining from 10% MSC group was higher than in 0% MSC group (69.5% vs. 49.4%). ^* P = 0.05, Student’s t test. Scale bar is 200 μm in all images.