6-Nitro-2-(3-hydroxypropyl)-1H-benz[de]isoquinoline-1,3-dione,a potent antitumor agent,induces cell cycle arrest and apoptosis

Background. anticancer activities of several substituted naphthalimides (1h-benz[de]isoquinoline-1,3-diones) are well documented. some of them have undergone phase i-ii clinical trials. presently a series of ten n-(hydroxyalkyl) naphthalimides (compounds 1a-j) were evaluated as antitumor agents. methods. compounds 1a-j were initially screened in molt-4,hl-60 and u-937 human tumor cell lines and results were compared with established clinical drugs. cytotoxicities of compounds 1d and 1i were further evaluated in a battery of human tumor cell lines and in normal human peripheral blood mononuclear cells. cell cycle analysis of compound 1i treated molt-4 cells was studied by flow cytometry. its apoptosis inducing effect was carried out in molt-4 and hl-60 cells by flow cytometry using annexin v-fitc/pi double staining method. the activities of caspase-3 and caspase-6 in molt-4 cells following incubation with compound 1i were measured at different time intervals. morphology of the molt-4 cells after treatment with 1i was examined under light microscope and transmission electron microscope. 3h-thymidine and 3h-uridine incorporation in s-180 cells in vitro following treatment with 8 m concentration of compounds 1d and 1i were studied. results. 6-nitro-2-(3-hydroxypropyl)-1h-benz[de]isoquinoline-1,3-dione (compound 1i),has exhibited maximum activity as it induced significant cytotoxicity in 8 out of 13 cell lines employed. interestingly it did not show any cytotoxicity against human pbmc (ic50 value 273 m). cell cycle analysis of compound 1i treated molt-4 cells demonstrated rise in sub-g1 fraction and concomitant accumulation of cells in s and g2/m phases,indicating up-regulation of apoptosis along with mitotic arrest and/or delay in exit of daughter cells from mitotic cycle respectively. its apoptosis inducing effect was confirmed in flow cytometric study in molt-4 and the action was mediated by activation of both caspase 3 and 6. light and transmission electron microscopic studies corroborated its apoptosis inducing efficacy at a concentration of 10 m in molt-4 cells. its apoptosis induction was also observed in hl-60 cells to an extent much greater than well known apoptosis inducing agents as camptothecin and cis-platin at 10 m concentration each. it significantly inhibited dna and rna synthesis in s-180. conclusions. in essence,compound 1i showed potential as an antitumor agent. © 2010 mukherjee et al; licensee biomed central ltd.