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Phospho-aspirin-2 (MDC-22) inhibits estrogen receptor positive breast cancer growth both in vitro and in vivo by a redox-dependent effect.

Huang L, Wong CC, Cheng KW, Rigas B - PLoS ONE (2014)

Bottom Line: An upstream mediator of the signaling effects of PA-2 is RONS.PA-2 induced oxidative stress in vitro and in mice bearing MCF7 xenografts; its induction effect appears to be tumor-specific.Crucially, administration of N-acetylcysteine, a ROS scavenger, abrogated the effect of PA-2 on p53 acetylation and mitochondria translocation, thus identifying RONS as proximal molecules mediating the anticancer effect of PA-2.

View Article: PubMed Central - PubMed

Affiliation: Division of Cancer Prevention, Department of Medicine, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
Phospho-aspirin (PA-2) is a novel aspirin derivative that exhibits promising anticancer properties and is considerably safer than conventional aspirin. In this study, we investigated the chemotherapeutic efficacy of PA-2 in preclinical models of estrogen receptor positive (ER+) breast cancer and elucidated its mechanism of action. PA-2 inhibited the growth of ER+ cells more potently than aspirin in vitro, and exerted a triple cytokinetic effect that includes induction of apoptosis and cell cycle arrest as well as the inhibition of cell proliferation. PA-2 is highly efficacious in vivo, as treatment of established MCF7 xenografts with PA-2 induced tumor stasis (98.2% inhibition, p<0.01). PA-2 triggered the activation of p53-dependent apoptosis via two distinct mechanisms: 1) acetylation of p53 (at K373), which disrupts its interaction with its transcription repressor MDM2, and 2) translocation of p53 to the mitochondria leading to the dissipation of mitochondrial transmembrane potential (ΔΨ(m)). Consistent with these observations, both the RNAi-mediated knockdown of p53 and forced deactylation via HDAC1 over-expression attenuated the anticancer effect of PA-2 in MCF7 cells. An upstream mediator of the signaling effects of PA-2 is RONS. PA-2 induced oxidative stress in vitro and in mice bearing MCF7 xenografts; its induction effect appears to be tumor-specific. Crucially, administration of N-acetylcysteine, a ROS scavenger, abrogated the effect of PA-2 on p53 acetylation and mitochondria translocation, thus identifying RONS as proximal molecules mediating the anticancer effect of PA-2. In summary, our findings demonstrate that PA-2 is a promising antineoplastic compound against ER+ breast cancer, warranting further evaluation as an anticancer agent.

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Phospho-aspirin-2 induces mitochondrial translocation of p53 and mitochondria-dependent apoptosis.A: The mitochondrial, cytosolic and nuclear levels of p53 and cytochrome c were determined after treatment with PA-2 by western blot. B: PA-2 caused the collapse of mitochondrial membrane potential (Δψm), as indicated by the increased JC-1 fluorescence relative to the control. C: Mitochondria-depleted MCF7 cells (ρ0) showed resistance to PA-2. Left: Immunoblotting of control and ρ0 MCF7 cell lysates for the specific marker mitochondrial protein COXIV (top) and the effect of PA-2 on the viability of parental and ρ0 MCF7 cells was determined by the MTT assay (bottom). Right: ρ0 MCF7 cells were resistant to PA-2-induced apoptotic cell death, as measured by Annexin V/PI staining and flow cytometry (results are the average of three independent experiments, *p<0.05).
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pone-0111720-g005: Phospho-aspirin-2 induces mitochondrial translocation of p53 and mitochondria-dependent apoptosis.A: The mitochondrial, cytosolic and nuclear levels of p53 and cytochrome c were determined after treatment with PA-2 by western blot. B: PA-2 caused the collapse of mitochondrial membrane potential (Δψm), as indicated by the increased JC-1 fluorescence relative to the control. C: Mitochondria-depleted MCF7 cells (ρ0) showed resistance to PA-2. Left: Immunoblotting of control and ρ0 MCF7 cell lysates for the specific marker mitochondrial protein COXIV (top) and the effect of PA-2 on the viability of parental and ρ0 MCF7 cells was determined by the MTT assay (bottom). Right: ρ0 MCF7 cells were resistant to PA-2-induced apoptotic cell death, as measured by Annexin V/PI staining and flow cytometry (results are the average of three independent experiments, *p<0.05).

Mentions: Recent evidence has indicated that p53 translocates to the mitochondria upon various stress stimuli to trigger apoptosis via opening of the mitochondrial permeability transition pore [23]. Hence, we analyzed the subcellular localization (cytosolic, mitochondria and nuclear) of p53 after treatment with 1.5xIC50 PA-2. As shown in Fig. 5A, PA-2 treatment resulted in significant accumulation of p53 in the mitochondria and cytochrome c release into cytosol in both cell lines (the mitochondrial p53 level increased 3.2-fold in MCF-7 cells and 2.4-fold in T-47D cells; the cytosolic cytochrome c level increased 1.8-fold in MCF-7 and 1.7-fold in T-47D cells), whereas the levels of cytosol and nuclear p53 remained unchanged. This observation indicates that PA-2 induced shuttling of p53 to the mitochondria. To evaluate whether PA-2 also regulates opening of the mitochondrial permeability transition pore (PTP), we measured mitochondrial membrane potential (Δψm) using the JC-1 fluorescence probe. Indeed, treatment with PA-2 in MCF7 cells significantly depolarized the mitochondrial membrane by 43% (Fig. 5B).


Phospho-aspirin-2 (MDC-22) inhibits estrogen receptor positive breast cancer growth both in vitro and in vivo by a redox-dependent effect.

Huang L, Wong CC, Cheng KW, Rigas B - PLoS ONE (2014)

Phospho-aspirin-2 induces mitochondrial translocation of p53 and mitochondria-dependent apoptosis.A: The mitochondrial, cytosolic and nuclear levels of p53 and cytochrome c were determined after treatment with PA-2 by western blot. B: PA-2 caused the collapse of mitochondrial membrane potential (Δψm), as indicated by the increased JC-1 fluorescence relative to the control. C: Mitochondria-depleted MCF7 cells (ρ0) showed resistance to PA-2. Left: Immunoblotting of control and ρ0 MCF7 cell lysates for the specific marker mitochondrial protein COXIV (top) and the effect of PA-2 on the viability of parental and ρ0 MCF7 cells was determined by the MTT assay (bottom). Right: ρ0 MCF7 cells were resistant to PA-2-induced apoptotic cell death, as measured by Annexin V/PI staining and flow cytometry (results are the average of three independent experiments, *p<0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219766&req=5

pone-0111720-g005: Phospho-aspirin-2 induces mitochondrial translocation of p53 and mitochondria-dependent apoptosis.A: The mitochondrial, cytosolic and nuclear levels of p53 and cytochrome c were determined after treatment with PA-2 by western blot. B: PA-2 caused the collapse of mitochondrial membrane potential (Δψm), as indicated by the increased JC-1 fluorescence relative to the control. C: Mitochondria-depleted MCF7 cells (ρ0) showed resistance to PA-2. Left: Immunoblotting of control and ρ0 MCF7 cell lysates for the specific marker mitochondrial protein COXIV (top) and the effect of PA-2 on the viability of parental and ρ0 MCF7 cells was determined by the MTT assay (bottom). Right: ρ0 MCF7 cells were resistant to PA-2-induced apoptotic cell death, as measured by Annexin V/PI staining and flow cytometry (results are the average of three independent experiments, *p<0.05).
Mentions: Recent evidence has indicated that p53 translocates to the mitochondria upon various stress stimuli to trigger apoptosis via opening of the mitochondrial permeability transition pore [23]. Hence, we analyzed the subcellular localization (cytosolic, mitochondria and nuclear) of p53 after treatment with 1.5xIC50 PA-2. As shown in Fig. 5A, PA-2 treatment resulted in significant accumulation of p53 in the mitochondria and cytochrome c release into cytosol in both cell lines (the mitochondrial p53 level increased 3.2-fold in MCF-7 cells and 2.4-fold in T-47D cells; the cytosolic cytochrome c level increased 1.8-fold in MCF-7 and 1.7-fold in T-47D cells), whereas the levels of cytosol and nuclear p53 remained unchanged. This observation indicates that PA-2 induced shuttling of p53 to the mitochondria. To evaluate whether PA-2 also regulates opening of the mitochondrial permeability transition pore (PTP), we measured mitochondrial membrane potential (Δψm) using the JC-1 fluorescence probe. Indeed, treatment with PA-2 in MCF7 cells significantly depolarized the mitochondrial membrane by 43% (Fig. 5B).

Bottom Line: An upstream mediator of the signaling effects of PA-2 is RONS.PA-2 induced oxidative stress in vitro and in mice bearing MCF7 xenografts; its induction effect appears to be tumor-specific.Crucially, administration of N-acetylcysteine, a ROS scavenger, abrogated the effect of PA-2 on p53 acetylation and mitochondria translocation, thus identifying RONS as proximal molecules mediating the anticancer effect of PA-2.

View Article: PubMed Central - PubMed

Affiliation: Division of Cancer Prevention, Department of Medicine, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
Phospho-aspirin (PA-2) is a novel aspirin derivative that exhibits promising anticancer properties and is considerably safer than conventional aspirin. In this study, we investigated the chemotherapeutic efficacy of PA-2 in preclinical models of estrogen receptor positive (ER+) breast cancer and elucidated its mechanism of action. PA-2 inhibited the growth of ER+ cells more potently than aspirin in vitro, and exerted a triple cytokinetic effect that includes induction of apoptosis and cell cycle arrest as well as the inhibition of cell proliferation. PA-2 is highly efficacious in vivo, as treatment of established MCF7 xenografts with PA-2 induced tumor stasis (98.2% inhibition, p<0.01). PA-2 triggered the activation of p53-dependent apoptosis via two distinct mechanisms: 1) acetylation of p53 (at K373), which disrupts its interaction with its transcription repressor MDM2, and 2) translocation of p53 to the mitochondria leading to the dissipation of mitochondrial transmembrane potential (ΔΨ(m)). Consistent with these observations, both the RNAi-mediated knockdown of p53 and forced deactylation via HDAC1 over-expression attenuated the anticancer effect of PA-2 in MCF7 cells. An upstream mediator of the signaling effects of PA-2 is RONS. PA-2 induced oxidative stress in vitro and in mice bearing MCF7 xenografts; its induction effect appears to be tumor-specific. Crucially, administration of N-acetylcysteine, a ROS scavenger, abrogated the effect of PA-2 on p53 acetylation and mitochondria translocation, thus identifying RONS as proximal molecules mediating the anticancer effect of PA-2. In summary, our findings demonstrate that PA-2 is a promising antineoplastic compound against ER+ breast cancer, warranting further evaluation as an anticancer agent.

Show MeSH
Related in: MedlinePlus