4-Amino-1,8-naphthalimide: a novel inhibitor of poly(ADP-ribose) polymerase and radiation sensitizer

Publisher Website
Google Scholar
Abstract
Purpose: Poly(ADP-ribose) polymerase (PARP; EC 2.4.2.30) is a chromatin-bound enzyme which is known to regulate chromatin structure by poly(ADP-ribosyl)ation of nuclear proteins, to facilitate DNA base excision repair, and to contribute to cellular recovery following DNA damage. Because inhibitors of PARP are able to potentiate the cell-killing e ects of some DNAdamaging agents and to inhibit the repair of induced DNA strand breaks, such compounds may enhance the anti-tumour e cacy of radiotherapy or cytotoxic drug treatment. The PARPinhibitory e ects and radiosensitization of a new compound, 4-amino-1,8-naphthalimide (ANI), were examined. Materials and methods: The inhibition of radiation-induced poly(ADP-ribosyl)ation (50Gy; 60Co gamma -radiation) was evaluated by immunofluorescence assay using MoAb 10H directed against poly(ADP-ribose). Cell survival was assessed by colony forming assay (CFA) to determine the cytotoxicity of radiosensitization potential in exponentially growing hamster lung fibroblasts (V79), rat prostate carcinoma (R3327-AT1) and human prostate carcinoma (DU145) cells. Results: At concentrations above 30nmol dm-3 ANI, radiationinduced poly(ADP-ribose) was not detectable by immunofluorescence in V79, AT1 and DU145 cells. At the highest concentration tested for chronic exposure (20 mu mol dm-3),ANI was not cytotoxic and significantly potentiates the cytotoxicity of gamma -irradiation. The level of radiation enhancement was directly proportional to drug concentration. Survival curves for the three cell lines using 20 mu mol dm-3 ANI revealed sensitizer enhancement ratios of 1.3 for V79, 1.5 for AT1 and 1.3 for DU145. Conclusions: In living cells, ANI is about 1000-fold more potent at inhibiting PARP activity compared with 3-aminobenzamide (3-ABA). CFA studies demonstrated that ANI is a radiation sensitizer at non-toxic and lower concentrations (20 mu mol dm-3) than 3-ABA (10mmol dm-3).

This publication has 0 references indexed in Scilit: