Joselina Magali Mondaca1, Ana Carla Castro Guijarro2, Marina Inés Flamini3, Angel Matias Sanchez4. 1. Laboratorio de Transducción de Señales y Movimiento Celular, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, Av. Ruiz Leal S/N. Parque Gral, San Martin CC855, 5500, Mendoza, Argentina. 2. Laboratorio de Biología Tumoral, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, Av. Ruiz Leal S/N. Parque Gral, San Martin CC855, 5500, Mendoza, Argentina. 3. Laboratorio de Biología Tumoral, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, Av. Ruiz Leal S/N. Parque Gral, San Martin CC855, 5500, Mendoza, Argentina. mflamini@mendoza-conicet.gov.ar. 4. Laboratorio de Transducción de Señales y Movimiento Celular, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, Av. Ruiz Leal S/N. Parque Gral, San Martin CC855, 5500, Mendoza, Argentina. amsanchez@mendoza-conicet.gov.ar.
Abstract
PURPOSE: Heregulin (HRG) signaling has been implicated in the development of an aggressive phenotype in breast cancer (BC) cells, and HER2 overexpression has been associated with a worse prognosis in BC patients. Nevertheless, the molecular mechanisms through which HRG affects the efficiency of anti-HER2 therapies such as trastuzumab (Tz) and trastuzumab-emtansine (T-DM1) are currently unknown. METHODS: In the present study, we evaluate the molecular action of HRG toward fundamental scaffold proteins and several kinases in the signal transduction pathways triggered via HER2/HER3, which integrate precise and sequential steps to promote changes in cell morphology to impulse BC cell migration. In addition, we evaluate the effectiveness of Tz and T-DM1 on the control of key proteins involved in BC cell motility, since the acquisition of a migratory phenotype is essential to promote invasion and metastasis. RESULTS: We show that HRG induces actin cytoskeleton reorganization and focal adhesion complex formation, and promotes actin nucleation in BT-474 BC cells. This signaling is triggered by HER2/HER3 to c-Src, FAK and paxillin. When paxillin is phosphorylated, it recruits PAK1, which then phosphorylates cortactin. In parallel, paxillin signals to N-WASP, and both signalings regulate Arp2/3 complex, leading to the local reorganization of actin fibers. CONCLUSIONS: Our findings reveal an original mechanism by which HRG increases HER2+ BC cell motility, and show that the latter can be abolished by Tz and T-DM1 treatments. These results provide evidence for the molecular mechanisms involved in cell motility and drug resistance. They will be useful to develop new and more specific therapeutic schemes that interfere with the progression and metastasis of HER2+ BC.
PURPOSE: Heregulin (HRG) signaling has been implicated in the development of an aggressive phenotype in breast cancer (BC) cells, and HER2 overexpression has been associated with a worse prognosis in BC patients. Nevertheless, the molecular mechanisms through which HRG affects the efficiency of anti-HER2 therapies such as trastuzumab (Tz) and trastuzumab-emtansine (T-DM1) are currently unknown. METHODS: In the present study, we evaluate the molecular action of HRG toward fundamental scaffold proteins and several kinases in the signal transduction pathways triggered via HER2/HER3, which integrate precise and sequential steps to promote changes in cell morphology to impulse BC cell migration. In addition, we evaluate the effectiveness of Tz and T-DM1 on the control of key proteins involved in BC cell motility, since the acquisition of a migratory phenotype is essential to promote invasion and metastasis. RESULTS: We show that HRG induces actin cytoskeleton reorganization and focal adhesion complex formation, and promotes actin nucleation in BT-474 BC cells. This signaling is triggered by HER2/HER3 to c-Src, FAK and paxillin. When paxillin is phosphorylated, it recruits PAK1, which then phosphorylates cortactin. In parallel, paxillin signals to N-WASP, and both signalings regulate Arp2/3 complex, leading to the local reorganization of actin fibers. CONCLUSIONS: Our findings reveal an original mechanism by which HRG increases HER2+ BC cell motility, and show that the latter can be abolished by Tz and T-DM1 treatments. These results provide evidence for the molecular mechanisms involved in cell motility and drug resistance. They will be useful to develop new and more specific therapeutic schemes that interfere with the progression and metastasis of HER2+ BC.
Entities:
Keywords:
Cellular motility; HER2+ breast cancer cells; HRG; Kinases and scaffold proteins; Trastuzumab and T-DM1
Authors: Hyun-Soo Cho; Karen Mason; Kasra X Ramyar; Ann Marie Stanley; Sandra B Gabelli; Dan W Denney; Daniel J Leahy Journal: Nature Date: 2003-02-13 Impact factor: 49.962
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