title: Rab11a differentially modulates epidermal growth factor-induced proliferation and motility in immortal breast cells.
abstract: The development of cancer prevention strategies depends on the elucidation of molecular pathways underlying oncogenesis. In a previous proteomic study of matched normal breast ducts and Ductal Carcinoma in Situ (DCIS), we identified overexpression of Rab11a in DCIS. Rab11a is not well studied in cancer, but is known to regulate the recycling of internalized cell surface proteins and receptors from the early endosome through the trans-Golgi network. Using immunohistochemistry, we confirmed our observation, noting increased Rab11a expression in 19 of 22 (86%) DCIS cases compared to matched normal breast epithelium. To study the function of Rab11a, immortal, nontumorigenic MCF10A breast cells were stimulated with ligands to the EGF receptor (EGFR) after transfection with empty vector (control), Rab11a, or a S25N dominant-negative (DN) Rab11a. Using an iodinated ligand:receptor recycling assay, transfection of Rab11a accelerated, while DN-Rab11a postponed EGFR recycling in vitro. The signaling and in vitro phenotypic consequences of Rab11a expression and function were studied. Transfection of DN-Rab11a increased Erk1/2 activation downstream of EGF, but exerted no effect on the Akt pathway. Expression of DN-Rab11a inhibited MCF10A proliferation by 50-60%, and also inhibited anchorage-dependent colonization. Notably, DN-Rab11a transfection increased motility toward EGFR ligands. The data provide a first demonstration that Rab11a modulates EGFR recycling, and promotes the proliferation but inhibits the motility of an immortal breast line, consistent with the DCIS phenotype.
authors.affiliation: Women's Cancers Section, Laboratory of Molecular Pharmacology, Laboratory of Pathology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20874, USA. palmierd@mail.nih.gov
authors.forename: Diane
authors.initials: D
authors.lastname: Palmieri
authors.forename: Amina
authors.initials: A
authors.lastname: Bouadis
authors.forename: Ruban
authors.initials: R
authors.lastname: Ronchetti
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Merino
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Steeg
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006801:Humans; D010766:Phosphorylation; D016211:Transforming Growth Factor alpha / Q000494:pharmacology; D020691:rab GTP-Binding Proteins / Q000502:physiology*; D000099193:rab11 GTP-Binding Proteins
chemical_list: D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D016211:Transforming Growth Factor alpha; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins