Stimulation of DNA synthesis in cultures of ovine mammary epithelial cells by insulin and insulin-like growth factors

in Journal of Endocrinology
Authors:
S. J. Winder
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A. Turvey
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I. A. Forsyth
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ABSTRACT

Ovine mammary epithelial cell clumps (30–90 μm) were plated onto attached gels of rat tail collagen in serum-free medium. Synthesis of DNA by these cultures could be stimulated by insulin-like growth factor-I (IGF-I) with a median effective dose of 5 μg/l, irrespective of stage of pregnancy. The time-course of response, however, was significantly slower in cells prepared from mammary tissue of non-pregnant and early pregnant sheep compared with sheep later in pregnancy. IGF-II had approximately 10% of the potency of IGF-I in stimulating DNA synthesis. Insulin acted over a wide concentration range and produced a maximum rate of stimulation not significantly different from that produced by IGF-I. These results are consistent with actions through the type-I IGF receptor although insulin may also act through its own receptor, possibly stimulating local IGF-I production. It is concluded that IGF-I is an important mitogen for ovine mammary epithelial cells.

Journal of Endocrinology (1989) 123, 319–326

 

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