Proteomics of transforming growth factor ?1 (TGF ?1) signaling in 184A1 human breast epithelial cells suggests the involvement of casein kinase 2? in TGF ?1-dependent p53 phosphorylation at Ser392

Abstract

Aim: Transforming growth factor ?1 (TGF ?1) is a potent regulator of breast tumorigenesis. It inhibits proliferation of carcinoma cells, but the strength of its inhibitory action varies for cells from benigh, non-metastatic or metastatic tumors. The aim of this work was to generate a proteome profile of TGF ?1 action on non-tumorigenic human breast epithelial cells 184A1, and validate predicted involvement of casein kinase 2? (CK2?), p53 and structure-specific recognition protein-1 (SSRP1). Materials and Methods: Two-dimensional gel electrophoresis and mass spectrometry were used to identify TGF ?1-regulated proteins in 184A1 human breast immortalized non-tumorigenic cells. 184A1 cells may serve as a model of benign breast neoplasia. These cells were obtained from normal mammary tissue, were immortalized but are not malignant, and were obtained from the American Type Culture Collection. The systemic analysis was performed by using the Cytoscape tool. Transfection of cells with CK2? construct and small interfering RNAs to CK2? and SSRP1 were used to assess an impact of CK2? and SSRP1 on phosphorylation of the p53 and cell proliferation. Results: Proliferation of 184A1 cells was transiently inhibited by TGF ?1. We identified 100 and 47 unique proteins which changed their expression and/or 35S-incorporation, respectively, upon treatment with TGF ?1 for 2 h, 8 h or 24 h. Cell proliferation, death, migration, and metabolism were among the biological regulatory processes retrieved by the network analysis as affected by the identified proteins. The network analysis suggested that TGF ?1 may affect the phosphorylation of p53 at Ser392 by engaging CK2?. This was confirmed by the immunoblotting and cell proliferation assays. Conclusion: We report here the list of 147 TGF ?1-regulated proteins in immortalized non-tumorigenic human breast epithelial cells, and show involvement of CK2? in the regulation of p53 Ser392 phosphorylation.