S179D-human PRL, a pseudophosphorylated human PRL analog, is an agonist and not an antagonist.
For many years, our group has been involved in the development of human PRL antagonists. In two recent publications, S179D-human PRL, a human PRL analog designed to mimic a putative S179-phosphorylated human PRL, was reported to be a highly potent antagonist of human PRL-induced proliferation and signaling in rat Nb2 cells. We prepared this analog with the aim of testing it in various bioassays involving the homologous, human PRL receptor. In our hands, S179D- human PRL was able to stimulate 1) the proliferation of rat Nb2 cells and of human mammary tumor epithelial cells (T-47D), 2) transcriptional activation of the lactogenic hormone response element-luciferase reporter gene, and 3) activation of the Janus kinase/signal transducer and activator of transcription and MAPK pathways. Using the previously characterized antagonist G129R-human PRL as a control, we failed to observe any evidence for antagonism of S179D-human PRL toward any of the human PRL-induced effects analyzed, including cell proliferation, transcriptional activation, and signaling. In conclusion, our data argue that S179D-human PRL is an agonist displaying slightly reduced affinity and activity due to local alteration of receptor binding site 1, and that the antagonistic properties previously attributed to S179D-human PRL cannot be confirmed in any of the assays analyzed in this study.
Bernichtein
S
S
INSERM, U-344, Molecular Endocrinology, Faculté de Médecine Necker, 75730 Paris, France.
Kinet
S
S
Jeay
S
S
Llovera
M
M
Madern
D
D
Martial
J A
JA
Kelly
P A
PA
Goffin
V
V
D000818:Animals; D001665:Binding Sites / Q000502:physiology; D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics; D006801:Humans; D053614:Janus Kinase 2; D008894:Milk Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D011388:Prolactin / Q000819:agonists* / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D011518:Proto-Oncogene Proteins; D051381:Rats; D011981:Receptors, Prolactin / Q000378:metabolism; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology
D004268:DNA-Binding Proteins; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D011981:Receptors, Prolactin; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; C422171:prolactin, Asp(179)-; D011388:Prolactin; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; C507927:Jak2 protein, rat; D053614:Janus Kinase 2; D020928:Mitogen-Activated Protein Kinases