Phosphoaspirin (MDC-43), a novel benzyl ester of aspirin, inhibits the growth of human cancer cell lines more potently than aspirin: A redox-dependent effect

Department of Medicine, Division of Cancer Prevention, Stony Brook University, Stony Brook, NY 11794-5200, USA.
Carcinogenesis (Impact Factor: 5.33). 02/2009; 30(3):512-9. DOI: 10.1093/carcin/bgp015
Source: PubMed


Aspirin is chemopreventive against colon and probably other cancers, but this effect is relatively weak and its chronic administration to humans is associated with significant side effects. Because of these limitations, extensive effort has been exerted to improve the pharmacological properties of aspirin. We have determined the anticancer activity and mechanisms of action of the novel para positional isomer of phosphoaspirin [P-ASA; MDC-43; 4-((diethoxyphosphoryloxy)methyl)phenyl 2-acetoxybenzoate]. P-ASA inhibited the growth of 10 human cancer cell lines originating from colon, lung, liver, pancreas and breast, at least 18- to 144-fold more potently than conventional aspirin. P-ASA achieved this effect by modulating cell kinetics; compared with controls, P-ASA reduced cell proliferation by up to 68%, increased apoptosis 5.5-fold and blocked cell cycle progression in the G(2)/M phase. P-ASA increased intracellular levels of reactive oxygen species (ROS), depleted glutathione levels and modulated cell signaling predominantly through the mitogen-activated protein kinase (p38 and c-jun N-terminal kinase), cyclooxygenase (COX) and nuclear factor-kappa B pathways. P-ASA targeted the mitochondria, increasing mitochondrial superoxide anion levels; this effect on ROS led to collapsed mitochondrial membrane potential and triggered the intrinsic apoptotic pathway. The antioxidant N-acetyl cysteine abrogated the cell growth inhibitory and signaling effects of P-ASA, underscoring the centrality of ROS in its mechanism of action. Our results, establishing P-ASA as a potent inhibitor of the growth of several human cancer cell lines, suggest that it may possess broad anticancer properties. We conclude that the novel P-ASA is a promising anticancer agent, which merits further evaluation.

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    • "To determine cell proliferation, we measured the incorporation of 5-bromo-2′-deoxyuridine (BrdU) into newly synthesized cellular DNA followed by the manufacture’s protocol (BD Biosciences), and cells were subjected to flow cytometric analysis. Cell cycle phase distribution was analyzed by flow cytometry as described [15]. "
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    • "Interestingly, VPA had no effect on mitochondrial STAT3 levels. In contrast, phospho-aspirin, which shares with P-V the same aromatic linker [13], reduced mitochondrial STAT3 levels (Fig. 3B), suggesting that the linker moiety may participate in this effect. None of these three compounds affected the mitochondrial levels of Hsp90 and Hsp60 proteins, both imported into the mitochondria, indicating that the changes in STAT3 levels were not due to a generalized suppression of protein transport into the mitochondria. "
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