Proteomics of transforming growth factorβ1(TGFβ1) signaling in 184A1 human breast epithelial cells suggests the involvement of casein kinase2α inTGFβ1-dependent p53 phosphorylation at Ser392.

Abstract

Transforming growth factorβ1 (TGFβ1) 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 TGFβ1action on non-tumorigenic human breast epithelial cells 184A1, and validate predicted involvement of casein kinase 2α (CK2α), p53and structure-specific recognition protein-1 (SSRP1). Two-dimensional gel electrophoresis and mass spectrometry were used to identify TGF β1-regulated proteins in 184A1human breast immortalized non-tumorigenic cells. 184A1cells 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 CK2α construct and small interfering RNAs to CK2α and SSRP1were used to assess an impact of CK2α and SSRP1on phosphorylation of the p53and cell proliferation. Proliferation of 184A1cells was transiently inhibited by TGF β1. We identified 100and 47unique proteins which changed their expression and/or 35S-incorporation, respectively, upon treatment with TGF β1for 2h, 8h or 24h. 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 β1may affect the phosphorylation of p53at Ser392by engaging CK2α. This was confirmed by the immunoblotting and cell proliferation assays. We report here the list of 147TGF β1-regulated proteins in immortalized non-tumorigenic human breast epithelial cells, and show involvement of CK2α in the regulation of p53Ser392phosphorylation.