Signaling and cellular
The most important intracellular pathways activated by HER2 are those involving mitogen activated protein kinase (MAPK) and phosphatidylinositol-3 kinase (PI3K). HER2 expression in cancer, besides its role in proliferation, enhances and prolongs survivals signals, associating up-regulation of this receptor to the malignant phenotype. At the same time, and depending on cellular status, the role of this receptor in controlling cell fate can also lead to differentiation and apoptosis.
Role in development and differentiation:
- HER2 has several non-oncogenic roles in regulating growth, differentiation, apoptosis and/or remodeling in normal mammary glands. Dominant-negative forms of HER2 have significant defects in mammary development and lactation.
- HER2 has an important role in development and function of heart. Cre-Lox technology to mutate erbB-2 specifically in ventricular cardiomyocytes leads to a severe cardiomyopathy. This is inferred also by the adverse cardiac side effects observed in breast cancer patients treated with the monoclonal anti-HER2 Ab Trastuzumab.
- HER2 has a role in control of Schwann cell myelination and it has been demonstrated that HER2 signaling is also critical for oligodendrocyte differentiation in vivo.
- HER2 has a dual role in both muscle spindle maintenance and survival of myoblasts. Muscle-specific HER2 KO results in fact in viable mice with a progressive defect in proprioception due to loss of muscles spindles.
Luca Braccioli ; Marilena V Iorio ; Patrizia Casalini
ERBB2 (v-erb-b2 erythroblastic leukemia viral oncogene homolog 2, neuro/glioblastoma derived oncogene homolog (avian))
Atlas Genet Cytogenet Oncol Haematol. 2011-05-01
Online version: http://atlasgeneticsoncology.org/gene/162/erbb2-(v-erb-b2-erythroblastic-leukemia-viral-oncogene-homolog-2-neuro-glioblastoma-derived-oncogene-homolog-(avian))
2004-12-01 ERBB2 (v-erb-b2 erythroblastic leukemia viral oncogene homolog 2, neuro/glioblastoma derived oncogene homolog (avian)) by Patrizia Casalini,Marilena V Iorio