Increased synergistic effect of EGF and IGF-I on DNA synthesis of cultured psoriatic keratinocytes.
BACKGROUND
DNA synthesis is significantly more stimulated in response to insulin-like growth factor I (IGF-I) in growth-arrested cultures of psoriatic than of nonpsoriatic keratinocytes. Epidermal growth factor (EGF), by itself only a weak stimulator, was recently found to cause a strong synergetic effect when added together with IGF-I to newborn human keratinocytes.


OBJECTIVE
(1) To measure this effect in cultured adult psoriatic and nonpsoriatic keratinocytes, and (2) to examine whether the difference in DNA synthesis after IGF-I addition could be due to differences in the binding of this growth factor.


METHODS
3H-deoxythymidine incorporation and 125I-IGF-I binding studies.


RESULTS
Psoriatic keratinocytes demonstrate a considerably stronger response to the combination of EGF and IGF-I than nonpsoriatic keratinocytes. This is apparently not caused by differences in binding of IGF-I.


CONCLUSIONS
Differences in the proliferative rate of normal and psoriatic keratinocytes may be in part due to differences in signal transduction distal from the IGF-I receptor or in the cooperation of the EGF and the IGF-I receptor.
Ristow
H J
HJ
Dermatology Service, Veterans Affairs Medical Center, Decatur, GA 30033, USA.
D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis*; D004357:Drug Synergism; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism*; D008875:Middle Aged; D011565:Psoriasis / Q000378:metabolism*
D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D004247:DNA