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Identification of 5-Iodotubercidin as a genotoxic drug with anti-cancer potential.

Zhang X, Jia D, Liu H, Zhu N, Zhang W, Feng J, Yin J, Hao B, Cui D, Deng Y, Xie D, He L, Li B - PLoS ONE (2013)

Bottom Line: We found that 5-Iodotubercidin could cause DNA damage, verified by induction of DNA breaks and nuclear foci positive for γH2AX and TopBP1, activation of Atm and Chk2, and S15 phosphorylation and up-regulation of p53.Moreover, 5-Iodotubercidin showed anti-tumor activity as it could reduce the tumor size in carcinoma xenograft mouse models in p53-dependent and -independent manners.These findings reveal 5-Iodotubercidin as a novel genotoxic drug that has chemotherapeutic potential.

View Article: PubMed Central - PubMed

Affiliation: Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China.

ABSTRACT
Tumor suppressor p53, which is activated by various stress and oncogene activation, is a target for anti-cancer drug development. In this study, by screening panels of protein kinase inhibitors and protein phosphatase inhibitors, we identified 5-Iodotubercidin as a strong p53 activator. 5-Iodotubercidin is purine derivative and is used as an inhibitor for various kinases including adenosine kinase. We found that 5-Iodotubercidin could cause DNA damage, verified by induction of DNA breaks and nuclear foci positive for γH2AX and TopBP1, activation of Atm and Chk2, and S15 phosphorylation and up-regulation of p53. As such, 5-Iodotubercidin induces G2 cell cycle arrest in a p53-dependent manner. Itu also induces cell death in p53-dependent and -independent manners. DNA breaks were likely generated by incorporation of 5-Iodotubercidin metabolite into DNA. Moreover, 5-Iodotubercidin showed anti-tumor activity as it could reduce the tumor size in carcinoma xenograft mouse models in p53-dependent and -independent manners. These findings reveal 5-Iodotubercidin as a novel genotoxic drug that has chemotherapeutic potential.

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Identification of Itu as a p53 activator.A. The structures of Itu, adenosine, and Fludarabine. B. Western blot shows that Itu up-regulates p53 in MEFs in a dose-dependent manner. Cells were treated with various concentrations of Itu for 8 hrs and the levels of p53 were analyzed by western blot. C. Western blot shows that Itu up-regulates p53 in HCT116 cells in a dose-dependent manner. Cells were treated with various concentrations of Itu for 8 hrs and the levels of p53 were analyzed by western blot. A longer-exposed film was also shown to indicate that p53 was expressed in HCT116 cells at the basal level. D. Knock-down of ADK did not activate p53. Left panel: the decrease of ADK mRNA in the presence of ADK siRNA; Right panel: the protein levels of p53 in the presence of control and ADK siRNA in HCT116 cells.
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pone-0062527-g001: Identification of Itu as a p53 activator.A. The structures of Itu, adenosine, and Fludarabine. B. Western blot shows that Itu up-regulates p53 in MEFs in a dose-dependent manner. Cells were treated with various concentrations of Itu for 8 hrs and the levels of p53 were analyzed by western blot. C. Western blot shows that Itu up-regulates p53 in HCT116 cells in a dose-dependent manner. Cells were treated with various concentrations of Itu for 8 hrs and the levels of p53 were analyzed by western blot. A longer-exposed film was also shown to indicate that p53 was expressed in HCT116 cells at the basal level. D. Knock-down of ADK did not activate p53. Left panel: the decrease of ADK mRNA in the presence of ADK siRNA; Right panel: the protein levels of p53 in the presence of control and ADK siRNA in HCT116 cells.

Mentions: To search for p53 activators, we screened by western blot analysis a panel of kinase inhibitors and a panel of phosphatase inhibitors to look for known compounds that could up-regulate p53 at the protein levels (for the list of the inhibitors, see Table S1) [17]. Primary MEFs were used for the screening because cell lines usually carry mutations in p53 and/or its upstream regulators. These inhibitors were applied at 10 µM, the concentration recommended by the manufacturer for inhibition of kinases or phosphatases. Two compounds out of the 113 inhibitors were able to induce p53 expression at the protein levels. One is 5-Iodotubercidin (Fig. 1A), a compound that is used as an inhibitor for adenosine kinase and other kinases such as Erk2. Itu has been shown to have anticonvulsant activity as well [19]. Itu-induced p53 up-regulation was observed in both MEFs and HCT116, with the latter being a colon cancer cell line positive for p53 (Fig. 1B and 1C). Dosage experiments indicated that Itu was able to up-regulate p53 at concentrations as low as 0.25 µM (Fig. 1B and 1C).


Identification of 5-Iodotubercidin as a genotoxic drug with anti-cancer potential.

Zhang X, Jia D, Liu H, Zhu N, Zhang W, Feng J, Yin J, Hao B, Cui D, Deng Y, Xie D, He L, Li B - PLoS ONE (2013)

Identification of Itu as a p53 activator.A. The structures of Itu, adenosine, and Fludarabine. B. Western blot shows that Itu up-regulates p53 in MEFs in a dose-dependent manner. Cells were treated with various concentrations of Itu for 8 hrs and the levels of p53 were analyzed by western blot. C. Western blot shows that Itu up-regulates p53 in HCT116 cells in a dose-dependent manner. Cells were treated with various concentrations of Itu for 8 hrs and the levels of p53 were analyzed by western blot. A longer-exposed film was also shown to indicate that p53 was expressed in HCT116 cells at the basal level. D. Knock-down of ADK did not activate p53. Left panel: the decrease of ADK mRNA in the presence of ADK siRNA; Right panel: the protein levels of p53 in the presence of control and ADK siRNA in HCT116 cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646850&req=5

pone-0062527-g001: Identification of Itu as a p53 activator.A. The structures of Itu, adenosine, and Fludarabine. B. Western blot shows that Itu up-regulates p53 in MEFs in a dose-dependent manner. Cells were treated with various concentrations of Itu for 8 hrs and the levels of p53 were analyzed by western blot. C. Western blot shows that Itu up-regulates p53 in HCT116 cells in a dose-dependent manner. Cells were treated with various concentrations of Itu for 8 hrs and the levels of p53 were analyzed by western blot. A longer-exposed film was also shown to indicate that p53 was expressed in HCT116 cells at the basal level. D. Knock-down of ADK did not activate p53. Left panel: the decrease of ADK mRNA in the presence of ADK siRNA; Right panel: the protein levels of p53 in the presence of control and ADK siRNA in HCT116 cells.
Mentions: To search for p53 activators, we screened by western blot analysis a panel of kinase inhibitors and a panel of phosphatase inhibitors to look for known compounds that could up-regulate p53 at the protein levels (for the list of the inhibitors, see Table S1) [17]. Primary MEFs were used for the screening because cell lines usually carry mutations in p53 and/or its upstream regulators. These inhibitors were applied at 10 µM, the concentration recommended by the manufacturer for inhibition of kinases or phosphatases. Two compounds out of the 113 inhibitors were able to induce p53 expression at the protein levels. One is 5-Iodotubercidin (Fig. 1A), a compound that is used as an inhibitor for adenosine kinase and other kinases such as Erk2. Itu has been shown to have anticonvulsant activity as well [19]. Itu-induced p53 up-regulation was observed in both MEFs and HCT116, with the latter being a colon cancer cell line positive for p53 (Fig. 1B and 1C). Dosage experiments indicated that Itu was able to up-regulate p53 at concentrations as low as 0.25 µM (Fig. 1B and 1C).

Bottom Line: We found that 5-Iodotubercidin could cause DNA damage, verified by induction of DNA breaks and nuclear foci positive for γH2AX and TopBP1, activation of Atm and Chk2, and S15 phosphorylation and up-regulation of p53.Moreover, 5-Iodotubercidin showed anti-tumor activity as it could reduce the tumor size in carcinoma xenograft mouse models in p53-dependent and -independent manners.These findings reveal 5-Iodotubercidin as a novel genotoxic drug that has chemotherapeutic potential.

View Article: PubMed Central - PubMed

Affiliation: Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China.

ABSTRACT
Tumor suppressor p53, which is activated by various stress and oncogene activation, is a target for anti-cancer drug development. In this study, by screening panels of protein kinase inhibitors and protein phosphatase inhibitors, we identified 5-Iodotubercidin as a strong p53 activator. 5-Iodotubercidin is purine derivative and is used as an inhibitor for various kinases including adenosine kinase. We found that 5-Iodotubercidin could cause DNA damage, verified by induction of DNA breaks and nuclear foci positive for γH2AX and TopBP1, activation of Atm and Chk2, and S15 phosphorylation and up-regulation of p53. As such, 5-Iodotubercidin induces G2 cell cycle arrest in a p53-dependent manner. Itu also induces cell death in p53-dependent and -independent manners. DNA breaks were likely generated by incorporation of 5-Iodotubercidin metabolite into DNA. Moreover, 5-Iodotubercidin showed anti-tumor activity as it could reduce the tumor size in carcinoma xenograft mouse models in p53-dependent and -independent manners. These findings reveal 5-Iodotubercidin as a novel genotoxic drug that has chemotherapeutic potential.

Show MeSH
Related in: MedlinePlus