Bif-1 suppresses breast cancer cell migration by promoting EGFR endocytic degradation.
Dysregulation of EGFR expression and signaling is well documented to contribute to disease progression and metastasis in many types of cancer including breast cancer. EGF-stimulated EGFR activation leads to receptor internalization and endocytic degradation to control EGFR-mediated signaling. This process is frequently deregulated in cancer cells, leading to increased EGFR expression and mitogenic signaling. Here, we demonstrate that Bif-1, a tumor suppressor, plays a role in EGFR endocytic degradation and chemotactic migration in MDA-MB-231 breast cancer cells. Our data reveal that suppression of Bif-1 expression delays EGFR degradation and sustains Erk1/2 activation in response to EGF stimulation. Mechanistically, loss of Bif-1 sequesters internalized EGF in Rab5-positive endosomes and delays EGFR trafficking to lysosomes. Recruitment of Rab7 to EGF-positive vesicles and the activation of Rab7 are impaired in Bif-1 knockdown cells. Additionally, intracellular pH and the localization of acidic vesicles are altered by suppression of Bif-1. Furthermore, inhibition of Bif-1 increases chemotactic cell migration in response to EGF or serum, which correlates with prolonged cytoskeletal reorganization. Importantly, the effect of Bif-1 on EGF-induced cell migration is abolished by gefitinib, an EGFR-specific inhibitor. Taken together, these data suggest a novel function for Bif-1 as a suppressor of breast cancer cell migration by promoting EGFR degradation through the regulation of endosome maturation.
Department of Pharmacology and Penn State Hershey Cancer Institute, The Pennsylvania State University College of Medicine, Hershey, PA, USA.
Kristin B
KB
Runkle
Cheryl L
CL
Meyerkord
Neelam V
NV
Desai
Yoshinori
Y
Takahashi
Hong-Gang
HG
Wang
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics*; D002633:Chemotaxis; D003599:Cytoskeleton / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000378:metabolism; D021381:Protein Transport; D059748:Proteolysis; D022161:Transport Vesicles / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000090802:rab7 GTP-Binding Proteins
D048868:Adaptor Proteins, Signal Transducing; C429293:SH3GLB1 protein, human; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D020691:rab GTP-Binding Proteins