Proteomic and phosphoproteomic alterations in benign, premalignant and tumor human breast epithelial cells and xenograft lesions: biomarkers of progression.

ABSTRACT

The MCF10A human breast epithelial cell lineage includes the benign MCF10A cells, premalignant cells (MCF10AT, MCF10ATG3B) and malignant MCF10CA1a tumor cells. The premalignant and tumor cells recapitulate the progressive alterations associated with the temporal development of PBD and carcinoma. Ras protein levels were elevated by 6.9-, 22.4- and 32.2-fold in 10AT, 10ATG3B and 10CA1a cells, respectively, relative to 10A cells. K-Ras was not detected, N-Ras levels were unchanged; Rac and Rho levels increased in 10CA1a tumor cells. Phospho-phosphatidylinositol 3-kinase, phosphoinositide-dependent protein kinase 1 (PDK1), phospho-PDK1, phospho-eukaryotic translation initiation factor 4E (eIF4E) and phospho-eukaryotic initiation factor 4E binding protein 1 (4E-BP1) levels progressively increased in the cell lineage, with the greatest increase monitored in 10CA1a tumor cells. Phospho Ser 473 and Thr 408 Akt levels increased 10.2- and 136-fold in 10CA1a cells, respectively, relative to 10A cells. Phospho-p70S6 kinase (p70S6K) increased >2-fold in 10CA1a cells, relative to 10A cells. Immunohistochemistry confirmed Ras, phospho-Akt and phospho-p70S6K (Thr 421/ Ser 424) expression in lesions arising from premalignant and tumor cells. FOXO 1, phospho-FOXO 1 and phospho-FOXO 4 were significantly elevated in 10ATG3B premalignant and 10CA1a tumor cells. Phospho-FOXO 3a was progressively elevated, with the greatest levels detected in 10CA1a tumor cells. Immunohistochemistry revealed that phospho-FOXO 1, 3a and 4 staining was less in benign lesions, but elevated in advanced 10ATG3B and malignant 10CA1a lesions, showing a correspondence between the cells and lesions. Hence, phospho-Akt and phospho-FOXO 1, 3a and 4 merit consideration as biomarkers of tumorigenic risk from hyperplastic breast tissue.