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.

Studies on stimulation of DNA synthesis with epidermal growth factor and insulin-like growth factor-I in cultured human keratinocytes.

Epidermal growth factor (EGF) and insulin are the most widely used growth factors (GFs) in human keratinocyte cultures. Insulin is supposed to exert its growth-promoting activity in this system through the insulin-like growth factor-I (IGF-I) receptor. In order to obtain more information about the contribution of EGF and IGF-I to the proliferation of keratinocytes, the effect of each factor on DNA synthesis was studied with 3H thymidine incorporation in an otherwise GF-free system.

Chromosomal damages by ethanol and acetaldehyde in Saccharomyces cerevisiae as studied by pulsed field gel electrophoresis.

We report on the effect of ethanol and acetaldehyde on yeast chromosomal DNA and on isolated DNA. Ethanol induced DNA single-strand breaks in repair deficient but not in repair proficient Saccharomyces cerevisiae. Acetaldehyde has a deleterious effect on chromosomal DNA in cells as well as on isolated DNA.

Effect of insulin-like growth factor-I/somatomedin C on thymidine incorporation in cultured psoriatic keratinocytes after growth arrest in growth factor-free medium.

Near confluent cultures of human keratinocytes will arrest in GO/G1 of the cell cycle when they are placed into growth factor (GF)-free medium with a Ca++ concentration below 0.1 mM for 4 days. Addition of certain growth factors will stimulate the cell to re-enter the growth cycle and move into the S-phase after 7-12 h.

Interleukin-1 does not stimulate DNA synthesis of cultured human keratinocytes growth-arrested in growth-factor-depleted medium.

Interleukin-1, a multifunctional cytokine, plays a central role in inflammatory processes. Several reports have appeared demonstrating that IL-1 stimulates growth of keratinocytes under certain experimental conditions, and we have shown previously that it can act as a strong stimulator of DNA synthesis in murine keratinocytes that have been growth-arrested by removal of growth factors (GF) from the medium for several days. Using the same assay system, we report here that, in contrast to cultured mouse keratinocytes, growth-arrested adult and newborn human keratinocytes do not respond to IL-1 with an increase in DNA synthesis.