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British Journal of Cancer Mar 2002We have analysed the mechanism of action for induction of apoptosis by N-substituted benzamides using declopramide as a lead compound. We show here that declopramide at...
We have analysed the mechanism of action for induction of apoptosis by N-substituted benzamides using declopramide as a lead compound. We show here that declopramide at doses above 250 microM in the mouse 70Z/3 pre-B cell line or in the human promyeolocytic cancer cell line HL60 induced cytochrome c release into the cytosol and caspase-9 activation. The broad spectrum caspase inhibitor zVADfmk and caspase-9 inhibitor zLEDHfmk inhibited apoptosis and improved cell viability when administrated to cells 1 h before exposure to declopramide, whereas the caspase-8 inhibitor zIEDHfmk had less effect. Also, the over expression of Bcl-2 by transfection in 70Z/3 cells inhibited declopramide-induced apoptosis. Prior to the induction of apoptosis, a G(2)/M cell cycle block was induced by declopramide. The cell cycle block was also observed in the presence of broad spectrum caspase inhibitor zVADfmk and in a transfectant expressing high levels of Bcl-2. Furthermore, while p53 was induced in 70Z/3 cells by declopramide, neither the apoptotic mechanism nor the G(2)/M cell cycle block were dependent on p53 activation since both effects were also seen in p53 deficient HL60 cells after addition of declopramide.
Topics: Apoptosis; Benzamides; Caspase 9; Caspases; Cytochrome c Group; Enzyme Activation; G2 Phase; HL-60 Cells; Humans; Metoclopramide; Mitosis; Procainamide; Proto-Oncogene Proteins c-bcl-2; Tumor Suppressor Protein p53
PubMed: 11953831
DOI: 10.1038/sj.bjc.6600136 -
British Journal of Cancer Nov 1999Benzamides have been in clinical use for many years in treatment against various disorders. A recent application is that as a sensitizer for radio- or chemotherapies. We...
Benzamides have been in clinical use for many years in treatment against various disorders. A recent application is that as a sensitizer for radio- or chemotherapies. We have here analysed the mechanism of action of N-substituted benzamides using an in vitro system. We found that while procainamide was biologically inert in our system, the addition of a chloride in the 3' position of the benzamide ring created a compound (declopramide) that induced rapid apoptosis. Furthermore, declopramide also inhibited NFkappaB activation by inhibition of IkappaBbeta breakdown. An acetylated variant of declopramide, N-acetyl declopramide, showed no effect with regard to rapid apoptosis induction but was a potent inhibitor of NFkappaB activation. In fact, the addition of an acetyl group to procainamide in the 4' position was sufficient to convert this biologically inactive substance to a potent inhibitor of NFkappaB activation. These findings suggest two potential mechanisms, induction of early apoptosis and inhibition of NFkappaB mediated salvage from apoptosis, for the biological effect of N-substituted benzamides as radio- and chemo-sensitizers. In addition it suggests that N-substituted benzamides are potential candidates for the development of anti-inflammatory compounds using NFkappaB as a drug target.
Topics: Apoptosis; Benzamides; Humans; NF-kappa B; Platelet Aggregation Inhibitors; Procainamide; Tumor Cells, Cultured
PubMed: 10576654
DOI: 10.1038/sj.bjc.6690796