Prolactin signaling to pim-1 expression: a role for phosphatidylinositol 3-kinase.
Sublines of the lactogen-dependent, rat pre-T Nb2 lymphoma are useful as a model for the investigation of prolactin (PRL) signaling mechanisms, regulation of transcription of target genes, and the immunomodulatory and anti-apoptotic actions of the hormone in T lymphocytes. In the present study, coupling of various tyrosine, serine/threonine, and phospholipid kinase signaling mechanisms to PRL-stimulated Nb2-11 cell proliferation and expression of the protooncogene, pim-1, was investigated utilizing pharmacologic antagonists of a broad spectrum of tyrosine kinases (tyrphostin A25), and the specific enzymes, Jak2 (tyrphostin B42) and ZAP-70 (piceatannol), as well as mitogen-activated protein kinase (MAPK, PD98059), protein kinase C (PKC, calphostin C), and phosphatidylinositol 3-kinase (PI3-kinase, LY294002). Inhibition of each pathway attenuated PRL-stimulated Nb2-11 cell proliferation in a concentration-dependent manner. Blockade of MAPK was the least efficacious; it inhibited proliferation maximally by 60%. Northern blot analysis of pim-1 expression in antagonist-treated cells revealed that MAPK, Jak2 and PI3-kinase appeared to signal to initiation of pim-1 transcription; its expression was attenuated by each of the antagonists. In other experiments, PRL was shown to rapidly activate a downstream effector of PI3-kinase, Akt, and this effect was also blocked by LY294002. It is concluded that PRL-stimulated Nb2 cell proliferation requires participation of each of the signaling pathways investigated. Moreover, hormone-mediated expression of pim-1 appears to reflect signaling by MAPK, Jak2, and PI3-kinase.
Krumenacker
J S
JS
College of Pharmacy and Department of Molecular and Cellular Physiology, University of Cincinnati Medical Center, 3223 Eden Avenue, P.O. Box 670004, Cincinnati, OH 45267-0004, USA.
Narang
V S
VS
Buckley
D J
DJ
Buckley
A R
AR
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053614:Janus Kinase 2; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D010770:Phosphotransferases / Q000037:antagonists & inhibitors; D011388:Prolactin / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051573:Proto-Oncogene Proteins c-pim-1; D051381:Rats; D015398:Signal Transduction / Q000502:physiology*; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology; D051746:ZAP-70 Protein-Tyrosine Kinase
D004791:Enzyme Inhibitors; D053614:Janus Kinase 2; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D010770:Phosphotransferases; D011388:Prolactin; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051573:Proto-Oncogene Proteins c-pim-1; D051746:ZAP-70 Protein-Tyrosine Kinase; C507927:Jak2 protein, rat; C496637:Pim1 protein, rat