ACTIVATION OF THE HUMAN-IMMUNODEFICIENCY-VIRUS PROMOTER BY UVA RADIATION IN COMBINATION WITH PSORALENS OR ANGELICINS

The effects of mono- and bifunctional furocoumarins plus UVA radiation (PUVA and related treatments) on the human immunodeficiency virus-1 ( HIV-1) promoter were studied using HeLa cells stably transfected with the chloramphenicol acetyl transferase gene under the control of the H IV-1 promoter. The experiments were performed with three psoralens (5- methoxypsoralen, 5-MOP; 8-methoxypsoralen, 8-MOP; and 4'-aminomethyl-4 ,8,5'-trimethyl-psoralen, AMT) and four angelicins (angelicin: 4,5'-di methylangelicin, 4,5'-DMA; 6,4'-dimethylangelicin, 6,4'-DMA; and 4,6,4 '-trimethylangelicin, TMA). The drugs alone and UVA radiation alone sh owed no effect on the HIV promoter. However, when the cells were incub ated with the furocoumarins at 0.1-40 mug/mL and then irradiated, the HIV promoter was activated in distinct fluence ranges, i.e. (1) no pro moter activity was discernible at low fluences (e.g. at 0.1 mug/mL of 8-MOP up to 100 kJ/m2), (2) as the fluence was increased, the promoter activity increased to reach a maximum (10-50-fold with respect to the unexposed samples), and (3) as the fluence was further increased, the promoter activity decreased. Similar (although shifted on the fluence scale) patterns were observed with either >340-nm UVA radiation or wi th UVA radiation contaminated with a small amount of UVB radiation (ty pical for PUVA lamps). The effective fluences were inversely related t o the drug concentration. Experiments with 5-MOP and 8-MOP indicated r eciprocity of the drug concentration and radiation fluence. The HIV pr omoter response patterns were similar for monofunctional angelicins an d bifunctional psoralens. This indicated that the furocoumarin-DNA cro ss-links are not a prerequisite for the promoter activation and that t he monoadducts suffice to elicit the HIV promoter response. The HIV pr omoter-activating effectiveness of different drugs correlated with the ir photosensitizing potential. Thus, among psoralens the effectiveness order was AMT > 5-MOP > 8-MOP, and among angelicins: TMA > 6,4'-DMA > 4,5'-DMA > angelicin. The effectiveness did not vary substantially fo r 5-MOP, 8-MOP, 4,5'-DMA, and 6,4'-DMA. The combined drug and UVA radi ation doses were higher than those that elicit cellular responses or t hose that may be received by the human white blood cells during extrac orporeal PUVA therapy (photopheresis).