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Growth stimulation by PGE 2 and EGF activates cyclic AMP‐dependent and ‐independent pathways in primary cultures of mouse mammary epithelial cells
Author(s) -
Imagawa Walter,
Bandyopadhyay Gautam K.,
Wallace Daiana,
Nandi Satyabrata
Publication year - 1988
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/jcp.1041350320
Subject(s) - ibmx , epidermal growth factor , endocrinology , medicine , stimulation , phosphodiesterase inhibitor , forskolin , growth factor , phosphodiesterase , prostaglandin e , biology , second messenger system , chemistry , biochemistry , enzyme , receptor
Mammary epithelial cells from virgin Balb/c mice were isolated by collagenase digestion and cultured within collagen gels in serum‐free basal medium containing insulin (10 μg/ml). Previous work has shown that linoleate or its metabolite, prostglandin E 2 (PGE 2 ), stimulate the growth of these cells only in the presence of a growth stimulant such as epidermal growth factor (EGF). Since PGE 2 can stimulate cyclic AMP (cAMP) production, the role of cAMP in linoleate and EGF‐stimulated growth was examined. The cAMP phosphodiesterase inhibitor, IBMX (0.1 mM), was found to augment growth when cells were cultured in the presence of both EGF and linoleate or PGE 2 , but not either factor alone. These results indicated that EGF does not stimulate proliferation via cyclic AMP mediated events but could synergize with cAMP events if cAMP levels were elevated by PGE 2 . When assayed in cells plated on top of collagen‐coated culture dishes, cellular cyclic AMP levels were stimulated by PGE 2 , but only marginally by EGF. Although the stimulation of endogenous cAMP by PGE 2 and IBMX was insufficient to stimulate growth in the absence of EGF, exogenous dibutyryl‐cAMP (>100 μg/ml) was able to do so showing that a sustained, and high level of cAMP (>100 μg/ml) could stimulate growth in insulin‐containing basal medium. EGF was capable of enhancing the cellular sensitivity to dibutyryl‐cAMP but the converse was not observed. cAMP stimulation of growth was dependent upon a superphysiological concentration of insulin (10 μg/ml) or a physiological concentration of somatomedin‐C. These results indicate that the proliferation of mouse mammary epithelial cells can be stimulated separately or in synergism by cAMP‐dependent or ‐independent events.