Src Mediates Prolactin-Dependent Proliferation of T47D and MCF7 Cells via the Activation of Focal Adhesion Kinase/Erk1/2 and Phosphatidylinositol 3-Kinase Pathways

• Published in: Molecular endocrinology (Baltimore, Md.) Md.), 2003-11, Vol.17 (11), p.2268-2282
• Main Authors: Acosta, Juan J, Muñoz, Raúl M, González, Lorena, Subtil-Rodríguez, Alicia, Domínguez-Cáceres, María Aurora, García-Martínez, José Manuel, Calcabrini, Annarica, Lazaro-Trueba, Iciar, Martín-Pérez, Jorge
• Format: Article
• Language: English
• Subjects: Animals; Cell Division - drug effects; Cell Line, Tumor; Cyclin D1 - metabolism; Enzyme Activation - drug effects; Focal Adhesion Kinase 1; Focal Adhesion Protein-Tyrosine Kinases; Humans; Mitogen-Activated Protein Kinases - antagonists & inhibitors; Mitogen-Activated Protein Kinases - metabolism; Phosphatidylinositol 3-Kinases - antagonists & inhibitors; Phosphatidylinositol 3-Kinases - metabolism; Phosphotyrosine - metabolism; Prolactin - pharmacology; Protein-Tyrosine Kinases - metabolism; Proto-Oncogene Proteins pp60(c-src) - antagonists & inhibitors; Proto-Oncogene Proteins pp60(c-src) - metabolism; Sheep; Signal Transduction - drug effects
• ISSN: 0888-8809; 1944-9917
• DOI: 10.1210/me.2002-0422

Prolactin (PRL) stimulates breast cancer cell proliferation; however, the involvement of PRL-activated signaling molecules in cell proliferation is not fully established. Here we studied the role of c-Src on PRL-stimulated proliferation of T47D and MCF7 breast cancer cells. We initially observed that PRL-dependent activation of focal adhesion kinase (Fak), Erk1/2, and cell proliferation was mediated by c-Src in T47D cells, because expression of a dominant-negative form of c-Src (SrcDM, K295A/Y527F) blocked the PRL-dependent effects. The Src inhibitor PP1 abrogated PRL-dependent in vivo activation of Fak, Erk1/2, p70S6K, and Akt and the proliferation of T47D and MCF7 cells; Janus kinase 2 (Jak2) activation was not affected. However, in vitro, Fak and Jak2 kinases were not directly inhibited by PP1, demonstrating the effect of PP1 on c-Src kinase as an upstream activator of Fak. Expression of Fak mutant Y397F abrogated PRL-dependent activation of Fak, Erk1/2, and thymidine incorporation, but had no effect on p70S6K and Akt kinases. MAPK kinase 1/2 (Mek1/2) inhibitor PD184352 blocked PRL-induced stimulation of Erk1/2 and cell proliferation; however, p70S6K and Akt activation were unaffected. The phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 abolished cell proliferation and activation of p70S6K and Akt; however, PRL-dependent activation of Erk1/2 was not modified. Moreover, we show that both c-Src/PI3K and c-Src/Fak/Erk1/2 pathways are involved in the up-regulation of c-myc and cyclin d1 expression mediated by PRL. The previous findings suggest the existence of two PRL-dependent signaling cascades, initiated by the c-Src-mediated activation of Fak/Erk1/2 and PI3K pathways that, subsequently, control the expression of c-Myc and cyclin D1 and the proliferation of T47D and MCF7 breast cancer cells.