Prolactin stimulates the JAK2 and focal adhesion kinase pathways in human breast carcinoma T47-D cells.
Treatment of T47-D human breast carcinoma cells with recombinant prolactin (rhPRL) induced a concentration- and time-dependent increase in the phosphotyrosine content of JAK2. rhPRL also stimulated JAK2 tyrosine phosphorylation more weakly in three other breast carcinoma lines, MCF-7, ZR-75-1 and MDA-MB-231. Furthermore it stimulated tyrosine phosphorylation of two isoforms of the transcriptional activator STAT5, STAT5a and STAT5b. Surprisingly, rhPRL treatment of T47-D cells also stimulated tyrosine phosphorylation of focal adhesion kinase (FAK), as determined by immunoprecipitation with anti-phosphotyrosine antibody followed by immunoblotting with a specific FAK antibody. The effect of rhPRL was rapid and concentration-dependent, being maximal at 5 ng/ml. At rhPRL concentrations above 25 ng/ml, FAK tyrosine phosphorylation declined but remained above control levels at 100 ng/ml. rhPRL also stimulated paxillin tyrosine phosphorylation in T47-D cells with similar concentration- and time-dependence. In a second human breast carcinoma cell line, MCF-7, rhPRL produced very similar effects on FAK and paxillin tyrosine phosphorylation. These findings identify a new protein tyrosine kinase pathway in the action of the lactogenic hormone rhPRL and represent the first report that a hormone acting through a member of the haemopoietin receptor superfamily can regulate the FAK/paxillin pathway.
Canbay
E
E
Department of Medicine, University of Bristol, Bristol Royal Infirmary, Marlborough Street, Bristol BS2 8HW, U.K.
Norman
M
M
Kilic
E
E
Goffin
V
V
Zachary
I
I
D001943:Breast Neoplasms; D015815:Cell Adhesion Molecules / Q000302:isolation & purification / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D005260:Female; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D053614:Janus Kinase 2; D007700:Kinetics; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011388:Prolactin / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D011388:Prolactin; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2; C496050:PTK2 protein, human