Di Stefano A, Trabalzini L, La Gaetana R, Parente L, Lusini P, Martelli P
Department of Molecular Biology, University of Siena, Italy.
Biochim Biophys Acta. 1995 Nov 9;1269(2):162-6. doi: 10.1016/0167-4889(95)00115-9.
Until recently, the therapeutic effects of furocoumarins and furochromones plus UV-A light were thought to be due to their ability to form photoadducts with DNA in the cell nuclei; now it appears that membrane effector systems may be involved as targets. Here we show that in HeLa cells khellin at 1 and 5 microM final concentration, in combination with UV-A light, inhibits NaF-stimulated adenylyl cyclase activity and Pertussis Toxin (PT)-catalyzed ADP-ribosylation of alpha-subunits of inhibitory guanine nucleotide regulatory proteins (Gi) and increases GTPase activity. In the same experimental conditions, 8-methoxypsoralen (8-MOP), either alone or plus UV-A, does not affect adenylyl cyclase and GTPase activities. Our results suggest that in HeLa cells, through an interaction with a receptor and the mediation of Gi proteins, the adenylyl cyclase system is a target for khellin but not for 8-MOP.
