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Pregnancy‐stimulated growth of vascular smooth muscle cells: Importance of protein kinase C‐dependent synergy between estrogen and platelet‐derived growth factor
Author(s) -
Keyes Linda E.,
Moore Lorna G.,
Walchak Sandra J.,
Dempsey Edward C.
Publication year - 1996
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199601)166:1<22::aid-jcp3>3.0.co;2-i
Subject(s) - medicine , endocrinology , vascular smooth muscle , platelet derived growth factor , estrogen , platelet derived growth factor receptor , growth factor , biology , alpha (finance) , uterine artery , receptor , pregnancy , gestation , smooth muscle , construct validity , nursing , patient satisfaction , genetics
Dramatic smooth muscle cell (SMC) growth occurs in the uterine artery during pregnancy. The potential for pregnancy‐associated growth may also exist at other vascular sites. We tested the hypothesis that increased growth of uterine artery SMC isolated from pregnant (vs. nonpregnant) guinea pigs would be detectable in culture, that pregnancy‐associated phenotypic changes would also be found in nonuterine vascular cells (aortic SMC), and that the enhanced growth would be dependent on estrogen, peptide growth factors like platelet‐derived growth factor (PDGF), and protein kinase C (PKC). Growth responses were measured by [ 3 H]‐thymidine incorporation and cell counts. Uterine artery SMC from pregnant guinea pigs grew to a higher plateau density with serum stimulation, had increased spontaneous DNA synthesis and persistent growth following serum withdrawal, and were more responsive to 3–30 ng/ml PDGF‐BB than nonpregnant cells. Aortic SMC from pregnant animals also grew to a higher plateau density and had enhanced responsiveness to PDGF‐BB. This increased response to PDGF‐BB by pregnant uterine artery and aortic SMC (40–233% increase over nonpregnant PDGF result) was reproduced in nonpregnant cells by pretreatment for 1–24 h with 17‐beta(β)‐estradiol (30–100 nM). Neither the pregnancy‐induced difference nor the estradiol pretreatment was associated with increased PDGF‐BB binding activity. The synergistic effect of 17β‐estradiol was partially (62%) reproduced with 17‐alpha(α)‐estradiol, an isomer which does not bind the estrogen receptor. This suggested that 17β‐estradiol modulates the PDGF‐BB response by both estrogen‐receptor‐ and nonreceptor‐mediated mechanisms. To test if the estrogen effects were dependent on PKC, two different antagonist strategies (3 μM dihydrosphingosine and phorbol‐ester‐induced downregulation) were applied prior to 17α‐ or β‐estradiol and blocked the enhanced responses to PDGF. The synergistic effect of 17β‐estradiol on PDGF was then reproduced by 1 h pretreatment with the cell‐permeable PKC activator, 10 nM PMA. We conclude that pregnancy stimulates increased growth of uterine and aortic SMC in vitro which is dependent on estrogen, PDGF, and PKC and may be important in vascular remodeling during pregnancy. © 1996 Wiley‐Liss, Inc.