Induction of apoptosis of human tumor cells by a 4,9-diazapyrenium derivative and its affects on topoisomerase-II action.
BACKGROUND
5,10-Diphenyl-4,9-dimethyl-4,9-diazapyrenium hydrogensulfate (FDAP) is a newly synthesized DNA intercalator with strong antiproliferative activity against various human tumor cells. In this study, FDAP's potential to induce apoptosis in human pancreatic (MIAPaCa-2) and colon (Caco-2) carcinoma cells and its effects on topoisomerase-II activity were investigated.


METHODS
Cytotoxicity was analyzed using the MTT assay. Antiproliferative activity was measured using a radioactive precursor incorporation assay. DNA fragmentation was analyzed by agarose gel electrophoresis. Apoptosis was detected using annexin-V fluorescein. To screen the topoisomerase-II-targeted effects of FDAP, cell-free assays were used.


RESULTS
FDAP at concentrations of 10 and 1 microM caused a strong cytotoxic effect on MIAPaCa-2 cells, but only a slight effect on WI38 cell viability. Inhibition of the DNA, RNA and protein synthesis of the treated tumor cells was dependent on cell type. The DNA of the treated MIAPaCa-2 cells was fragmented. Phosphatidylserine externalization was detected in both tumor cell lines investigated. FDAP caused generation of DNA strand breaks due to interaction with human topoisomerase-IIalpha.


CONCLUSIONS
1 microM FDAP caused apoptotic cell death of treated tumor cells. FDAP stimulated topoisomerase-II-mediated DNA cleavage and could be considered a topoisomerase-II poison.
Marczi
S
S
Scientific Unit for Clinical-Medical Research, Clinical Hospital Osijek, Osijek, Croatia.
Glavas-Obrovac
Lj
Lj
Karner
I
I
D017209:Apoptosis / Q000187:drug effects*; D018938:Caco-2 Cells; D004249:DNA Damage; D004250:DNA Topoisomerases, Type II / Q000187:drug effects* / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D010190:Pancreatic Neoplasms / Q000473:pathology; D011806:Quinolinium Compounds / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
C504891:5,10-diphenyl-4,9-dimethyl-4,9-diazapyrenium; D011806:Quinolinium Compounds; D004250:DNA Topoisomerases, Type II