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Histone deacetylase 8 is deregulated in urothelial cancer but not a target for efficient treatment.

Lehmann M, Hoffmann MJ, Koch A, Ulrich SM, Schulz WA, Niegisch G - J. Exp. Clin. Cancer Res. (2014)

Bottom Line: Efficient siRNA-mediated knockdown of HDAC8 reduced proliferation up to 45%.Expression of thymidylate synthase was partly reduced; PARP-cleavage was not detected.The influence of the pharmacological inhibition on clonogenic growth and migration show a cell line- and inhibitor-dependent reduction with the strongest effects after treatment with compound 5 and compound 6.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Previous studies have shown that class-I histone deacetylase (HDAC) 8 mRNA is upregulated in urothelial cancer tissues and urothelial cancer cell lines compared to benign controls. Using urothelial cancer cell lines we evaluated whether specific targeting of HDAC8 might be a therapeutic option in bladder cancer treatment.

Methods: We conducted siRNA-mediated knockdown and specific pharmacological inhibition of HDAC8 with the three different inhibitors compound 2, compound 5, and compound 6 in several urothelial carcinoma cell lines with distinct HDAC8 expression profiles. Levels of HDAC and marker proteins were determined by western blot analysis and mRNA levels were measured by quantitative real-time PCR. Cellular effects of HDAC8 suppression were analyzed by ATP assay, flow cytometry, colony forming assay and migration assay.

Results: Efficient siRNA-mediated knockdown of HDAC8 reduced proliferation up to 45%. The HDAC8 specific inhibitors compound 5 and compound 6 significantly reduced viability of all urothelial cancer cell lines (IC₅₀ 9 - 21 μM). Flow cytometry revealed only a slight increase in the sub-G1 fraction indicating a limited induction of apoptosis. Expression of thymidylate synthase was partly reduced; PARP-cleavage was not detected. The influence of the pharmacological inhibition on clonogenic growth and migration show a cell line- and inhibitor-dependent reduction with the strongest effects after treatment with compound 5 and compound 6.

Conclusions: Deregulation of HDAC8 is frequent in urothelial cancer, but neither specific pharmacological inhibition nor siRNA-mediated knockdown of HDAC8 impaired viability of urothelial cancer cell lines in a therapeutic useful manner. Accordingly, HDAC8 on its own is not a promising drug target in bladder cancer.

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Compensation mechanism after specific HDAC8 inhibition in RT-112, VM-CUB1, SW-1710, 639-V and UM-UC-3 cells. Effects of HDAC8 inhibitor treatment on (A) mRNA and (B) protein expression of the class I histone deacetylases HDAC8, HDAC1, HDAC2 and HDAC3, compared to DMSO solvent control (compound 2, compound 5, compound 6; IC50, 72 h). The mRNA expression values were measured by quantitative RT-PCR analysis and were normalized to TBP as a reference gene. p < 0.05 was regarded as significant and marked as *, whereas p < 0.01 and p < 0.001 were defined as highly significant and marked as ** and ***. The calculated significances of the treated value refer to the DMSO solvent control. Protein expression levels were analyzed by western blotting, and α-tubulin was stained on each blot as a loading control.
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Figure 12: Compensation mechanism after specific HDAC8 inhibition in RT-112, VM-CUB1, SW-1710, 639-V and UM-UC-3 cells. Effects of HDAC8 inhibitor treatment on (A) mRNA and (B) protein expression of the class I histone deacetylases HDAC8, HDAC1, HDAC2 and HDAC3, compared to DMSO solvent control (compound 2, compound 5, compound 6; IC50, 72 h). The mRNA expression values were measured by quantitative RT-PCR analysis and were normalized to TBP as a reference gene. p < 0.05 was regarded as significant and marked as *, whereas p < 0.01 and p < 0.001 were defined as highly significant and marked as ** and ***. The calculated significances of the treated value refer to the DMSO solvent control. Protein expression levels were analyzed by western blotting, and α-tubulin was stained on each blot as a loading control.

Mentions: To investigate whether inhibition of HDAC8 might be counteracted by concomitant upregulation of other class I-HDACs (HDAC1, HDAC2 and HDAC3) their expression levels were compared by real-time PCR and western blot analysis (Figures 11 and 12). In brief, HDAC1, HDAC2 and HDAC3 mRNA levels exhibited variable changes after siRNA-mediated knockdown of HDAC8. Both significant up-and downregulation of specific HDACs were observed. In particular, either HDAC1 or HDAC2 seems to become upregulated after HDAC8 knockdown (Figure 11A). Western blot analysis shown in Figure 11B revealed a decrease of HDAC2 protein in RT-112 cells and HDAC3 protein in UM-UC-3 cells after siRNA mediated HDAC8 knockdown. No significant deregulation of other class I-HDACs took place (Figure 11B).


Histone deacetylase 8 is deregulated in urothelial cancer but not a target for efficient treatment.

Lehmann M, Hoffmann MJ, Koch A, Ulrich SM, Schulz WA, Niegisch G - J. Exp. Clin. Cancer Res. (2014)

Compensation mechanism after specific HDAC8 inhibition in RT-112, VM-CUB1, SW-1710, 639-V and UM-UC-3 cells. Effects of HDAC8 inhibitor treatment on (A) mRNA and (B) protein expression of the class I histone deacetylases HDAC8, HDAC1, HDAC2 and HDAC3, compared to DMSO solvent control (compound 2, compound 5, compound 6; IC50, 72 h). The mRNA expression values were measured by quantitative RT-PCR analysis and were normalized to TBP as a reference gene. p < 0.05 was regarded as significant and marked as *, whereas p < 0.01 and p < 0.001 were defined as highly significant and marked as ** and ***. The calculated significances of the treated value refer to the DMSO solvent control. Protein expression levels were analyzed by western blotting, and α-tubulin was stained on each blot as a loading control.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4230422&req=5

Figure 12: Compensation mechanism after specific HDAC8 inhibition in RT-112, VM-CUB1, SW-1710, 639-V and UM-UC-3 cells. Effects of HDAC8 inhibitor treatment on (A) mRNA and (B) protein expression of the class I histone deacetylases HDAC8, HDAC1, HDAC2 and HDAC3, compared to DMSO solvent control (compound 2, compound 5, compound 6; IC50, 72 h). The mRNA expression values were measured by quantitative RT-PCR analysis and were normalized to TBP as a reference gene. p < 0.05 was regarded as significant and marked as *, whereas p < 0.01 and p < 0.001 were defined as highly significant and marked as ** and ***. The calculated significances of the treated value refer to the DMSO solvent control. Protein expression levels were analyzed by western blotting, and α-tubulin was stained on each blot as a loading control.
Mentions: To investigate whether inhibition of HDAC8 might be counteracted by concomitant upregulation of other class I-HDACs (HDAC1, HDAC2 and HDAC3) their expression levels were compared by real-time PCR and western blot analysis (Figures 11 and 12). In brief, HDAC1, HDAC2 and HDAC3 mRNA levels exhibited variable changes after siRNA-mediated knockdown of HDAC8. Both significant up-and downregulation of specific HDACs were observed. In particular, either HDAC1 or HDAC2 seems to become upregulated after HDAC8 knockdown (Figure 11A). Western blot analysis shown in Figure 11B revealed a decrease of HDAC2 protein in RT-112 cells and HDAC3 protein in UM-UC-3 cells after siRNA mediated HDAC8 knockdown. No significant deregulation of other class I-HDACs took place (Figure 11B).

Bottom Line: Efficient siRNA-mediated knockdown of HDAC8 reduced proliferation up to 45%.Expression of thymidylate synthase was partly reduced; PARP-cleavage was not detected.The influence of the pharmacological inhibition on clonogenic growth and migration show a cell line- and inhibitor-dependent reduction with the strongest effects after treatment with compound 5 and compound 6.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Previous studies have shown that class-I histone deacetylase (HDAC) 8 mRNA is upregulated in urothelial cancer tissues and urothelial cancer cell lines compared to benign controls. Using urothelial cancer cell lines we evaluated whether specific targeting of HDAC8 might be a therapeutic option in bladder cancer treatment.

Methods: We conducted siRNA-mediated knockdown and specific pharmacological inhibition of HDAC8 with the three different inhibitors compound 2, compound 5, and compound 6 in several urothelial carcinoma cell lines with distinct HDAC8 expression profiles. Levels of HDAC and marker proteins were determined by western blot analysis and mRNA levels were measured by quantitative real-time PCR. Cellular effects of HDAC8 suppression were analyzed by ATP assay, flow cytometry, colony forming assay and migration assay.

Results: Efficient siRNA-mediated knockdown of HDAC8 reduced proliferation up to 45%. The HDAC8 specific inhibitors compound 5 and compound 6 significantly reduced viability of all urothelial cancer cell lines (IC₅₀ 9 - 21 μM). Flow cytometry revealed only a slight increase in the sub-G1 fraction indicating a limited induction of apoptosis. Expression of thymidylate synthase was partly reduced; PARP-cleavage was not detected. The influence of the pharmacological inhibition on clonogenic growth and migration show a cell line- and inhibitor-dependent reduction with the strongest effects after treatment with compound 5 and compound 6.

Conclusions: Deregulation of HDAC8 is frequent in urothelial cancer, but neither specific pharmacological inhibition nor siRNA-mediated knockdown of HDAC8 impaired viability of urothelial cancer cell lines in a therapeutic useful manner. Accordingly, HDAC8 on its own is not a promising drug target in bladder cancer.

Show MeSH
Related in: MedlinePlus