Wild-type p53 inhibits pro-invasive properties of TGF- beta 3 in breast cancer, in part through regulation of EPHB2, a new TGF- beta target gene

The p53 tumor suppressor protein is primarily known for its important role in tumor suppression. In addition, p53 affects tumor cell migration, invasion, and epithelial-mesenchymal transition (EMT); processes also regulated by the transforming growth factor- beta (TGF- beta ) signaling pathway. Here, we investigated the role of p53 in breast tumor cell invasion, migration, and EMT and examined the interplay of p53 with TGF- beta 3 in these processes. MCF-10A1 and MCF-10CA1a breast cancer cells were treated with Nutlin-3 and TGF- beta 3, and the effects on tumor cell migration and invasion were studied in transwell and 3D spheroid invasion assays. The effects of Nutlin-3 and TGF- beta 3 on EMT were examined in NMuMG cells. To identify genes involved in TGF- beta -induced invasion that are modulated by p53, a Human Tumor Metastasis-specific RT-PCR array was performed. Verification of EPHB2 regulation by TGF- beta 3 and p53 was performed on breast cancer tumor cell lines. We demonstrate that p53 inhibits basal and TGF- beta 3-induced invasion, migration, and EMT in normal breast epithelial and breast cancer cells. Pharmacological activation of p53 inhibited induction of several TGF- beta 3 targets involved in TGF- beta 3-induced tumor cell invasion, i.e., matrix metallo proteinase (MMP)2, MMP9, and integrin beta sub(3) . The ephrin-type B receptor 2 (EPHB2) gene was identified as a new TGF- beta target important for TGF- beta 3-mediated invasion and migration, whose transcriptional activation by TGF- beta 3 is also inhibited by p53. The results show an intricate interplay between p53 and TGF- beta 3 whereby p53 inhibits the TGF- beta 3-induced expression of genes, e.g., EPHB2, to impede tumor cell invasion and migration.