L-Triiodothyronine stimulates growth by means of an autocrine factor in a cultured growth hormone-producing cell line

M. J. Miller, E. C. Fels, L. E. Shapiro, M. I. Surks

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L-Triiodothyronine (T3) stimulates DNA synthesis and replication of cultured GC cells, a T3-responsive growth hormone (GH)-secreting cell line. To determine whether T3 stimulates secretion of an autocrine growth factor, we compared the growth-promoting activity of medium conditioned by T3-stimulated and T3-depleted cells to that of unconditioned medium. Addition of polyclonal rabbit anti-T3 serum to T3-containing media decreased cellular T3 content by 50-70%. In unconditioned medium, anti-T3 serum decreased T3-induced cell growth and GH production by 40-70%. In conditioned medium, anti-T3 serum also effected a 45-70% decrease in induction of GH secretion but did not attenuate the growth-promoting activity. Growth-promoting activity was not detected in medium conditioned by T3-depleted cells. Thus, conditioned medium from T3-containing GC cell cultures contains growth-promoting activity that is independent of T3. Further, the induction of GC cell growth by T3 may occur, at least in part, by induction of an autocrine growth factor.

Original languageEnglish (US)
Pages (from-to)1773-1781
Number of pages9
JournalJournal of Clinical Investigation
Issue number6
Publication statusPublished - Jan 1 1987


ASJC Scopus subject areas

  • Medicine(all)

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