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HDAC inhibitor, scriptaid, induces glioma cell apoptosis through JNK activation and inhibits telomerase activity.

Sharma V, Koul N, Joseph C, Dixit D, Ghosh S, Sen E - J. Cell. Mol. Med. (2010)

Bottom Line: Although scriptaid induced activation of both p38MAPK and JNK, it was the inhibition of JNK that attenuated scriptaid-induced apoptosis significantly.Scriptaid also increased the expression of (i) p21 and p27 involved in cell-cycle regulation and (ii) γH2AX associated with DNA damage response in a JNK-dependent manner.Taken together, our findings indicate that scriptaid (i) induces apoptosis and reduces glioma cell proliferation by elevating JNK activation and (ii) also decreases telomerase activity in a JNK-independent manner.

View Article: PubMed Central - PubMed

Affiliation: National Brain Research Centre, Manesar, Haryana, India.

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Scriptaid increases the expression and activity of Ras in glioma cells. (A) Scriptaid increases Ras expression in glioma cells in a dose-dependent manner. LN229 and T98G cells were treated with different concentration of scriptaid, and Ras level was determined by Western blot analysis. A representative blot is shown from three independent experiments with identical results. Blots were reprobed for β-actin to establish equivalent loading. (B) Effects of scriptaid on the levels of GTP-bound Ras. The levels of Ras-GTP in protein extracts of control and scriptaidtreated LN229 and T98G cells were determined by the ability of Ras-GTP to bind to a specific protein domain of Raf in the form of a GST-fusion protein. An increase in Ras activity was observed in glioma cells treated with increasing concentration of scriptaid both at 1 and 24 hrs post-treatment, as compared to the control. The figure is representative from three independent experiments with identical results. (C) Scriptaidinduced cell death is dramatically increased in the presence of constitutive Ras. Glioma cells transfected with constitutive active Ras (RasV12) were treated with scriptaid for 24 hrs and cell viability was determined by MTS assay. Ras activity in cells transfected with RasV12 or control vector in the presence or absence of scriptaid. The graph represents the percentage of viable cells as determined by MTS assay, observed when RasV12-transfected or untransfected glioma cells were treated in the presence and absence of scriptaid for 24 hrs. Values represent the means ± SEM from three independent experiments. *Significant decrease from control (P≤ 0.05); #significant change from scriptaid-treated cells (P≤ 0.05).
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fig05: Scriptaid increases the expression and activity of Ras in glioma cells. (A) Scriptaid increases Ras expression in glioma cells in a dose-dependent manner. LN229 and T98G cells were treated with different concentration of scriptaid, and Ras level was determined by Western blot analysis. A representative blot is shown from three independent experiments with identical results. Blots were reprobed for β-actin to establish equivalent loading. (B) Effects of scriptaid on the levels of GTP-bound Ras. The levels of Ras-GTP in protein extracts of control and scriptaidtreated LN229 and T98G cells were determined by the ability of Ras-GTP to bind to a specific protein domain of Raf in the form of a GST-fusion protein. An increase in Ras activity was observed in glioma cells treated with increasing concentration of scriptaid both at 1 and 24 hrs post-treatment, as compared to the control. The figure is representative from three independent experiments with identical results. (C) Scriptaidinduced cell death is dramatically increased in the presence of constitutive Ras. Glioma cells transfected with constitutive active Ras (RasV12) were treated with scriptaid for 24 hrs and cell viability was determined by MTS assay. Ras activity in cells transfected with RasV12 or control vector in the presence or absence of scriptaid. The graph represents the percentage of viable cells as determined by MTS assay, observed when RasV12-transfected or untransfected glioma cells were treated in the presence and absence of scriptaid for 24 hrs. Values represent the means ± SEM from three independent experiments. *Significant decrease from control (P≤ 0.05); #significant change from scriptaid-treated cells (P≤ 0.05).

Mentions: Ras induces DNA damage signalling response [28] and cells that senesce in response to oncogenic Ras accumulate DNA damage foci [29]. Disruption of cooperation of Ras and cMyc promotes growth arrest of neuroblastoma cells [30]. Moreover, oncogenic Ras promotes HDAC inhibitor butyrate-induced apoptosis [31]. Because scriptaid-triggered apoptosis was concomitant with decrease in cMyc and increase in γ-H2AX, we investigated the contribution of Ras in scriptaid-induced apoptosis. Western blot analysis demonstrated an increase in Ras expression in LN229 and T98G cells upon increasing exposure to scriptaid (Fig. 5A).


HDAC inhibitor, scriptaid, induces glioma cell apoptosis through JNK activation and inhibits telomerase activity.

Sharma V, Koul N, Joseph C, Dixit D, Ghosh S, Sen E - J. Cell. Mol. Med. (2010)

Scriptaid increases the expression and activity of Ras in glioma cells. (A) Scriptaid increases Ras expression in glioma cells in a dose-dependent manner. LN229 and T98G cells were treated with different concentration of scriptaid, and Ras level was determined by Western blot analysis. A representative blot is shown from three independent experiments with identical results. Blots were reprobed for β-actin to establish equivalent loading. (B) Effects of scriptaid on the levels of GTP-bound Ras. The levels of Ras-GTP in protein extracts of control and scriptaidtreated LN229 and T98G cells were determined by the ability of Ras-GTP to bind to a specific protein domain of Raf in the form of a GST-fusion protein. An increase in Ras activity was observed in glioma cells treated with increasing concentration of scriptaid both at 1 and 24 hrs post-treatment, as compared to the control. The figure is representative from three independent experiments with identical results. (C) Scriptaidinduced cell death is dramatically increased in the presence of constitutive Ras. Glioma cells transfected with constitutive active Ras (RasV12) were treated with scriptaid for 24 hrs and cell viability was determined by MTS assay. Ras activity in cells transfected with RasV12 or control vector in the presence or absence of scriptaid. The graph represents the percentage of viable cells as determined by MTS assay, observed when RasV12-transfected or untransfected glioma cells were treated in the presence and absence of scriptaid for 24 hrs. Values represent the means ± SEM from three independent experiments. *Significant decrease from control (P≤ 0.05); #significant change from scriptaid-treated cells (P≤ 0.05).
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fig05: Scriptaid increases the expression and activity of Ras in glioma cells. (A) Scriptaid increases Ras expression in glioma cells in a dose-dependent manner. LN229 and T98G cells were treated with different concentration of scriptaid, and Ras level was determined by Western blot analysis. A representative blot is shown from three independent experiments with identical results. Blots were reprobed for β-actin to establish equivalent loading. (B) Effects of scriptaid on the levels of GTP-bound Ras. The levels of Ras-GTP in protein extracts of control and scriptaidtreated LN229 and T98G cells were determined by the ability of Ras-GTP to bind to a specific protein domain of Raf in the form of a GST-fusion protein. An increase in Ras activity was observed in glioma cells treated with increasing concentration of scriptaid both at 1 and 24 hrs post-treatment, as compared to the control. The figure is representative from three independent experiments with identical results. (C) Scriptaidinduced cell death is dramatically increased in the presence of constitutive Ras. Glioma cells transfected with constitutive active Ras (RasV12) were treated with scriptaid for 24 hrs and cell viability was determined by MTS assay. Ras activity in cells transfected with RasV12 or control vector in the presence or absence of scriptaid. The graph represents the percentage of viable cells as determined by MTS assay, observed when RasV12-transfected or untransfected glioma cells were treated in the presence and absence of scriptaid for 24 hrs. Values represent the means ± SEM from three independent experiments. *Significant decrease from control (P≤ 0.05); #significant change from scriptaid-treated cells (P≤ 0.05).
Mentions: Ras induces DNA damage signalling response [28] and cells that senesce in response to oncogenic Ras accumulate DNA damage foci [29]. Disruption of cooperation of Ras and cMyc promotes growth arrest of neuroblastoma cells [30]. Moreover, oncogenic Ras promotes HDAC inhibitor butyrate-induced apoptosis [31]. Because scriptaid-triggered apoptosis was concomitant with decrease in cMyc and increase in γ-H2AX, we investigated the contribution of Ras in scriptaid-induced apoptosis. Western blot analysis demonstrated an increase in Ras expression in LN229 and T98G cells upon increasing exposure to scriptaid (Fig. 5A).

Bottom Line: Although scriptaid induced activation of both p38MAPK and JNK, it was the inhibition of JNK that attenuated scriptaid-induced apoptosis significantly.Scriptaid also increased the expression of (i) p21 and p27 involved in cell-cycle regulation and (ii) γH2AX associated with DNA damage response in a JNK-dependent manner.Taken together, our findings indicate that scriptaid (i) induces apoptosis and reduces glioma cell proliferation by elevating JNK activation and (ii) also decreases telomerase activity in a JNK-independent manner.

View Article: PubMed Central - PubMed

Affiliation: National Brain Research Centre, Manesar, Haryana, India.

Show MeSH
Related in: MedlinePlus