Geldanamycin abrogates ErbB2 association with proteasome-resistant beta-catenin in melanoma cells, increases beta-catenin-E-cadherin association, and decreases beta-catenin-sensitive transcription.
Beta-catenin undergoes both serine and tyrosine phosphorylation. Serine phosphorylation in the amino terminus targets beta-catenin for proteasome degradation, whereas tyrosine phosphorylation in the COOH terminus influences interaction with E-cadherin. We examined the tyrosine phosphorylation status of beta-catenin in melanoma cells expressing proteasome-resistant beta-catenin, as well as the effects that perturbation of beta-catenin tyrosine phosphorylation had on its association with E-cadherin and on its transcriptional activity. Beta-catenin is tyrosine phosphorylated in three melanoma cell lines and associates with both the ErbB2 receptor tyrosine kinase and the LAR receptor tyrosine phosphatase. Geldanamycin, a drug which destabilizes ErbB2, caused rapid cellular depletion of the kinase and loss of its association with beta-catenin without perturbing either LAR or beta-catenin levels or LAR/beta-catenin association. Geldanamycin also stimulated tyrosine dephosphorylation of beta-catenin and increased beta-catenin/E-cadherin association, resulting in substantially decreased cell motility. Geldanamycin also decreased the nuclear beta-catenin level and inhibited beta-catenin-driven transcription, as assessed using two different beta-catenin-sensitive reporters and the endogenous cyclin D1 gene. These findings were confirmed by transient transfection of two beta-catenin point mutants, Tyr-654Phe and Tyr-654Glu, which, respectively, mimic the dephosphorylated and phosphorylated states of Tyr-654, a tyrosine residue contained within the beta-catenin-ErbB2-binding domain. These data demonstrate that the functional activity of proteasome-resistant beta-catenin is regulated further by geldanamycin-sensitive tyrosine phosphorylation in melanoma cells.
Department of Cell and Cancer Biology, Medicine Branch, National Cancer Institute, Rockville, Maryland 20850, USA.
P
P
Bonvini
W G
WG
An
A
A
Rosolen
P
P
Nguyen
J
J
Trepel
A
A
Garcia de Herreros
M
M
Dunach
L M
LM
Neckers
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D016227:Benzoquinones; D015820:Cadherins / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects; D003546:Cysteine Endopeptidases / Q000187:drug effects / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047029:Lactams, Macrocyclic; D008545:Melanoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009097:Multienzyme Complexes / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D010766:Phosphorylation; D017354:Point Mutation; D046988:Proteasome Endopeptidase Complex; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011809:Quinones / Q000494:pharmacology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4; D011956:Receptors, Cell Surface / Q000378:metabolism; D015534:Trans-Activators; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D051176:beta Catenin
D000903:Antibiotics, Antineoplastic; D016227:Benzoquinones; D015820:Cadherins; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors; D003598:Cytoskeletal Proteins; D047029:Lactams, Macrocyclic; D009097:Multienzyme Complexes; D009419:Nerve Tissue Proteins; D046988:Proteasome Endopeptidase Complex; D017027:Protein Tyrosine Phosphatases; D011809:Quinones; D018719:Erb-b2 Receptor Tyrosine Kinases; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4; D011956:Receptors, Cell Surface; D015534:Trans-Activators; D014443:Tyrosine; D051176:beta Catenin; C495270:CTNNB1 protein, human; C516841:PTPRA protein, human; C516772:PTPRF protein, human; C001277:geldanamycin