title: Phosphoinositide 3-kinase signaling is critical for ErbB3-driven breast cancer cell motility and metastasis.
abstract: Many malignancies show increased expression of the epidermal growth factor (EGF) receptor family member ErbB3 (HER3). ErbB3 binds heregulin β-1 (HRGβ1) and forms a heterodimer with other ErbB family members, such as ErbB2 (HER2) or EGF receptor (EGFR; HER1), enhancing phosphorylation of specific C-terminal tyrosine residues and activation of downstream signaling pathways. ErbB3 contains six YXXM motifs that bind the p85 subunit of phosphoinositide 3 (PI3)-kinase. Previous studies demonstrated that overexpression of ErbB3 in mammary tumor cells can significantly enhance chemotaxis to HRGβ1 and overall metastatic potential. We tested the hypothesis that ErbB3-mediated PI3-kinase signaling is critical for heregulin-induced motility, and therefore crucial for ErbB3-mediated invasion, intravasation and metastasis. The tyrosines in the six YXXM motifs on the ErbB3 C-terminus were replaced with phenylalanine. In contrast to overexpression of the wild-type ErbB3, overexpression of the mutant ErbB3 did not enhance chemotaxis towards HRGβ1 in vitro or in vivo. We also observed reduced tumor cell motility in the primary tumor by multiphoton microscopy, as well as a dramatically reduced ability of these cells to cross the endothelium and intravasate into the circulation. Moreover, whereas mutation of the ErbB3 C-terminus had no effect on tumor growth, it had a dramatic effect on spontaneous metastatic potential. Treatment with the PI3-kinase inhibitor PIK-75 similarly inhibited motility and invasion in vitro and in vivo. Our results indicate that stimulation of the early metastatic steps of motility and invasion by ErbB3 requires activation of the PI3-kinase pathway by the ErbB3 receptor.
authors: Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10801, USA.
authors: T
authors: T
authors: Smirnova
authors: Z N
authors: ZN
authors: Zhou
authors: R J
authors: RJ
authors: Flinn
authors: J
authors: J
authors: Wyckoff
authors: P J
authors: PJ
authors: Boimel
authors: M
authors: M
authors: Pozzuto
authors: S J
authors: SJ
authors: Coniglio
authors: J M
authors: JM
authors: Backer
authors: A R
authors: AR
authors: Bresnick
authors: J S
authors: JS
authors: Condeelis
authors: N E
authors: NE
authors: Hynes
authors: J E
authors: JE
authors: Segall
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D005260:Female; D006801:Humans; D006835:Hydrazones / Q000494:pharmacology; D047468:Immunoprecipitation; D015674:Mammary Neoplasms, Animal / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D016513:Mice, SCID; D036641:Microscopy, Fluorescence, Multiphoton; D009154:Mutation; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D020890:Neuregulin-1 / Q000378:metabolism / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011485:Protein Binding; D051381:Rats; D020893:Receptor, ErbB-3 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D013449:Sulfonamides / Q000494:pharmacology; D014183:Transplantation, Heterologous; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism
chemical_list: D006835:Hydrazones; D020890:Neuregulin-1; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D020893:Receptor, ErbB-3; D013449:Sulfonamides; D014443:Tyrosine; C549211:PIK 75; C087230:heregulin beta1