Effect of prostaglandins on H-thymidine uptake into human epidermal cells

Prostaglandins A₂, B₁, E₁, E₂, F_1α and F_2α were added to cultures of human epidermal cells (keratinocytes) for 24 hours at 37°C, and the effects on ³H-thymidine uptake into DNA was measured. At 70 μg/ml all prostaglandins tested except PGF_2α inhibited the uptake of ³H-thymidine greater than 50%. However, at 35 μg/ml, PGA₂ and PGB₁ were the only two prostaglandins to show significant inhibition, 96% and 51% respectively. At 17.5 μg/ml only PGA₂ caused substantial inhibition, 68%. In order to determine if the PGA₂ action was mediated by membrane receptors propranolol, phentolamine, metiamide and prostynoic acid were added in conjunction with PGA₂. None of the above receptor antagonists were able to reduce the PGA₂-induced inhibition of ³H-thymidine uptake. These results indicate that the pre-incubation of human keratinocytes with prostaglandins for 24 hours results in a decrease of ³H-thymidine incorporation in DNA. The precise mechanism of action is unknown at this time.