Induction of apoptosis in human cancer cell lines by the novel anthracenyl-amino acid topoisomerase I inhibitor NU/ICRF 505

Synthesis and evaluation of selected 1,3,4-oxadiazole derivatives for in vitro cytotoxicity and in vivo anti-tumor activity

The oxadiazole moiety is known for its anticancer activity through its antiangiogenic and mitostatic potential. Taking this as a cue, the present study was designed to investigate the anti-cancer potential of selected oxadiazole derivatives. Twelve 1,3,4-oxadiazole derivatives (AMK OX-1 to AMK OX-12) were synthesized and were tested for IC50 values through brine shrimp lethality assay and MTT assay on HeLa and A549 cell lines. Four compounds, AMK OX-8, 9, 11 and 12 showed potential cytotoxicity activity with low IC50 value. These compounds produced considerable cytotoxic effect on Hep-2 and A549 cancer cell lines. However, they were found to be comparatively safer to normal cell lines, viz., V-79 cell lines than to the tested cancer cell lines, such as HeLa, A 549, and Hep2 cell lines. The mechanism of cytotoxicity was evaluated through nuclear staining and DNA ladder assay. Although DNA ladder assay showed DNA fragmentation (apoptotic phenomenon) in Hep-2 cells treated with only AMK OX-12, the staining procedures using acridine orange, ethidium bromide and propidium iodide showed apoptotic bodies in cells treated with AMK OX-8, 9 and 12 also. In JCI staining on isolated mitochondria of Hep2 cells, AMK OX-8, 9-11 and 12 displayed increasing fluorescence intensity with time which confirmed involvement of mitochondrial pathway and intrinsic pathway of apoptosis. All four compounds were found to be safe in acute oral toxicity study in Swiss albino mice. These derivatives were effective in reducing tumor size and weight in the in vivo DLA-induced solid tumor model. They were found to be significantly effective in reducing tumor volume and tumor weight.

New 1,4-anthracene-9,10-dione derivatives as potential anticancer agents

The amino-substituted anthracene-9,10-dione (9,10-anthraquinone) derivatives represent one of the most important classes of potential anticancer agents. To better understand the basic rules governing DNA sequence specificity, we have recently synthesized a new class of D- and L-aminoacyl-anthraquinone derivatives. We have tested these new compounds as cytotoxic agents, and we have correlated their activity with the configuration of the chiral aminoacyl moiety. Molecular modeling studies have been performed to compare the test drugs in terms of steric overlapping.

Cell cycle effects of the novel topoisomerase I inhibitor NU/ICRF 505 in a panel of Chinese hamster ovary cell lines

The effect of the novel topoisomerase I inhibitor NU/ICRF 505 (20 microM, approximate IC50 concentration) on the cell cycle was studied by flow cytometry in four Chinese hamster ovary (CHO) cell lines. Postdrug treated cells were incubated with optimal concentrations of cytochalasin B to prevent re-entry of daughter cells into the cell cycle. NU/ICRF 505 had no significant effect on cell cycle distribution in the parent cell line (CHO-K1) and two mutants hypersensitive to topo II inhibitors (ADR-1, ADR-3), all of which express similar levels of topo I protein. In the drug-resistant variant ADR-r, which overexpresses topo I 2-fold, a significant accumulation of cells in G1 phase was recorded. These results are broadly consistent with the cell cycle effects expected in CHO cells by a classic topo I poison (camptothecin) and add weight to the view that NU/ICRF 505 induces cell death primarily through topo I inhibition.