title: Autocrine human growth hormone enhancement of human mammary carcinoma cell spreading is Jak2 dependent.
abstract: We investigated the role of autocrine production of human (h) GH in the attachment and spreading of mammary carcinoma cells in vitro. We used a previously described model system for the study of the autocrine/paracrine role of GH in which the hGH gene (MCF-hGH) or a translation-deficient hGH gene (MCF-MUT) was stably transfected into MCF-7 cells. No differences in attachment to a collagen matrix between MCF-hGH and MCF-MUT cells were observed in either serum-free medium (SFM) or medium containing exogenous hGH, 5% serum, or 10% serum. In contrast, MCF-hGH cells spread more rapidly on a collagen matrix than did MCF-MUT cells. Exogenous hGH and 10% serum interacted with autocrine production of hGH in an additive manner to increase cell spreading. MCF-hGH cells formed filipodia and stress fibers earlier than MCF-MUT cells during the process of cell spreading and possessed marked differences in morphology after spreading. MCF-MUT cells displayed uniform and symmetrical formation of stress fibers, whereas MCF-hGH cells displayed irregular and elongated stress fiber formation. The level of cytoplasmic phosphotyrosine was increased in MCF-hGH compared with MCF-MUT cells during spreading and displayed colocalization with Janus kinase 2 (JAK2). Basal JAK2 tyrosine phosphorylation was increased, and it increased further on spreading in MCF-hGH cells compared with MCF-MUT cells. Transient transfection of JAK2 complementary DNA resulted in interaction with autocrine hGH to increase the rate of cell spreading in MCF-hGH cells compared with MCF-MUT cells. Treatment with a selective JAK2 tyrosine kinase inhibitor (AG 490) reduced the rate of MCF-hGH cell spreading to the rate of MCF-MUT cell spreading. Thus, we conclude that autocrine production of hGH enhances the rate of mammary carcinoma cell spreading in a JAK2-dependent manner.
authors.affiliation: Department of Medicine, National University of Singapore, Republic of Singapore.
authors.forename: K K
authors.initials: KK
authors.lastname: Kaulsay
authors.forename: H C
authors.initials: HC
authors.lastname: Mertani
authors.forename: K O
authors.initials: KO
authors.lastname: Lee
authors.forename: P E
authors.initials: PE
authors.lastname: Lobie
mesh_terms: D000199:Actins / Q000502:physiology; D019898:Autocrine Communication / Q000502:physiology*; D001943:Breast Neoplasms / Q000473:pathology* / Q000503:physiopathology; D002277:Carcinoma / Q000473:pathology* / Q000503:physiopathology; D002448:Cell Adhesion; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D013006:Growth Hormone / Q000031:analogs & derivatives / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D019382:Human Growth Hormone / Q000502:physiology*; D006801:Humans; D053614:Janus Kinase 2; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D011518:Proto-Oncogene Proteins; D011986:Receptors, Somatotropin / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D000199:Actins; D004791:Enzyme Inhibitors; C093172:G120R protein, human; D006727:Hormone Antagonists; D011518:Proto-Oncogene Proteins; D011986:Receptors, Somatotropin; D011994:Recombinant Proteins; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D019382:Human Growth Hormone; D019000:Phosphotyrosine; D014443:Tyrosine; D013006:Growth Hormone; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2