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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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Related in: MedlinePlus

Itu generates DNA damage-induced nuclear foci.A. Treatment of HCT116 with 1 µM of Itu for 8 hrs induced nuclear foci positive for γH2AX, TopBP1, and activated Atm. Caffeine treatment diminished the formation of these foci. HCT116 cells were pretreated with caffeine (5 mM) for 1 hr and then Itu was added to the cultures for 8 more hrs. Cells were the fixed and stained for γH2AX, TopBP1, or p-Atm. B. Treatment of MEFs with 1 µM of Itu for 8 hrs induced nuclear foci positive for γH2AX, TopBP1, and activated Atm.
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pone-0062527-g003: Itu generates DNA damage-induced nuclear foci.A. Treatment of HCT116 with 1 µM of Itu for 8 hrs induced nuclear foci positive for γH2AX, TopBP1, and activated Atm. Caffeine treatment diminished the formation of these foci. HCT116 cells were pretreated with caffeine (5 mM) for 1 hr and then Itu was added to the cultures for 8 more hrs. Cells were the fixed and stained for γH2AX, TopBP1, or p-Atm. B. Treatment of MEFs with 1 µM of Itu for 8 hrs induced nuclear foci positive for γH2AX, TopBP1, and activated Atm.

Mentions: To validate this finding, we treated HCT116 and MEFs with Itu for 8 hrs and analyzed the formation of DNA damage-induced nuclear foci, which are postulated as DNA damage and repair centers [28], [29]. Among the earliest proteins assembled at the DNA breaks are γH2AX, a histone H2A variant that is ubiquitously expressed. It can be phosphorylated by PIKK members such as Atm and Atr quickly after DNA damage [30]. We did find that Itu treatment resulted in an accumulation of nuclear foci positive for γH2AX in both HCT116 (10.39±1.82% for untreated cells vs. 90.19±2.21% for Itu treated cells) and MEFs (7.45±0.29% for untreated cells vs. 91.63±0.73% for Itu treated cells) (Fig. 3A and 3B). Moreover, Itu treatment also resulted in an accumulation of nuclear foci positive for TopBP1, another foci-localized protein, in HCT116 (14.25±5.12% for untreated cells vs. 95.24±1.39% for Itu treated cells) and MEFs (13.08±5.15% for untreated cells vs. 93.32±2.70% for Itu treated cells) (Fig. 3A and 3B).


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)

Itu generates DNA damage-induced nuclear foci.A. Treatment of HCT116 with 1 µM of Itu for 8 hrs induced nuclear foci positive for γH2AX, TopBP1, and activated Atm. Caffeine treatment diminished the formation of these foci. HCT116 cells were pretreated with caffeine (5 mM) for 1 hr and then Itu was added to the cultures for 8 more hrs. Cells were the fixed and stained for γH2AX, TopBP1, or p-Atm. B. Treatment of MEFs with 1 µM of Itu for 8 hrs induced nuclear foci positive for γH2AX, TopBP1, and activated Atm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3646850&req=5

pone-0062527-g003: Itu generates DNA damage-induced nuclear foci.A. Treatment of HCT116 with 1 µM of Itu for 8 hrs induced nuclear foci positive for γH2AX, TopBP1, and activated Atm. Caffeine treatment diminished the formation of these foci. HCT116 cells were pretreated with caffeine (5 mM) for 1 hr and then Itu was added to the cultures for 8 more hrs. Cells were the fixed and stained for γH2AX, TopBP1, or p-Atm. B. Treatment of MEFs with 1 µM of Itu for 8 hrs induced nuclear foci positive for γH2AX, TopBP1, and activated Atm.
Mentions: To validate this finding, we treated HCT116 and MEFs with Itu for 8 hrs and analyzed the formation of DNA damage-induced nuclear foci, which are postulated as DNA damage and repair centers [28], [29]. Among the earliest proteins assembled at the DNA breaks are γH2AX, a histone H2A variant that is ubiquitously expressed. It can be phosphorylated by PIKK members such as Atm and Atr quickly after DNA damage [30]. We did find that Itu treatment resulted in an accumulation of nuclear foci positive for γH2AX in both HCT116 (10.39±1.82% for untreated cells vs. 90.19±2.21% for Itu treated cells) and MEFs (7.45±0.29% for untreated cells vs. 91.63±0.73% for Itu treated cells) (Fig. 3A and 3B). Moreover, Itu treatment also resulted in an accumulation of nuclear foci positive for TopBP1, another foci-localized protein, in HCT116 (14.25±5.12% for untreated cells vs. 95.24±1.39% for Itu treated cells) and MEFs (13.08±5.15% for untreated cells vs. 93.32±2.70% for Itu treated cells) (Fig. 3A and 3B).

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