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The novel histone deacetylase inhibitor, N-hydroxy-7-(2-naphthylthio) hepatonomide, exhibits potent antitumor activity due to cytochrome-c-release-mediated apoptosis in renal cell carcinoma cells.

Park KC, Heo JH, Jeon JY, Choi HJ, Jo AR, Kim SW, Kwon HJ, Hong SJ, Han KS - BMC Cancer (2015)

Bottom Line: Renal tumors have been shown to have a higher global methylation percentage and reduced histone acetylation.An in vivo study showed that HNHA had greater anti-tumor and pro-apoptotic effects on RCC xenografts than the established HDAC inhibitors.These results suggest that HNHA may offer a new therapeutic approach to RCC.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Epigenetic modifications play a critical role in the regulation of all DNA-based processes, such as transcription, repair, and replication. Inappropriate histone modifications can result in dysregulation of cell growth, leading to neoplastic transformation and cell death. Renal tumors have been shown to have a higher global methylation percentage and reduced histone acetylation. Preclinical models have revealed that histone gene modifiers and epigenetic alterations play important roles in renal cell carcinoma (RCC) tumorigenesis. Recently, a novel HDAC inhibitor, N-hydroxy-7-(2-naphthylthio) heptanomide (HNHA), has been introduced as an example of a new class of anti-cancer agents. The anti-cancer activity of HNHA and the underlying mechanisms of action remain to be clarified.

Methods: The MTS assay using a panel of RCC cells was used to evaluate the anti-proliferative effects of HNHA. The established HDAC inhibitors, SAHA and TSA, were used for comparison. Western blotting analysis was performed to investigate the acetylation of histone H3 and the expression of apoptotic markers in vitro and in vivo. Subcellular fractionation was performed to evaluate expression of Bax and cytochrome c in the cytosol and mitochondria, and also translocation of cytochrome c from the cytoplasm to the nucleus. A confocal microscopic evaluation was performed to confirm inhibition of cell proliferation, induction of apoptosis, and the nuclear translocation of cytochrome c in RCC cells.

Results: In this study, we investigated the apoptosis-inducing activity of HNHA in cultured kidney cancer cells. Apoptosis in the HNHA-treated group was induced significantly, with marked caspase activation and Bcl-2 suppression in RCC cells in vitro and in vivo. HNHA treatment caused cytochrome c release from mitochondria, which was mediated by increased Bax expression and caspase activation. HNHA also induced nuclear translocation of cytochrome c, suggesting that HNHA can induce caspase-independent nuclear apoptosis in RCC cells. An in vivo study showed that HNHA had greater anti-tumor and pro-apoptotic effects on RCC xenografts than the established HDAC inhibitors.

Conclusions: HNHA has more potent anti-tumor activity than established HDAC inhibitors. Its activities are mediated by caspase-dependent and cytochrome-c-mediated apoptosis in RCC cells. These results suggest that HNHA may offer a new therapeutic approach to RCC.

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HNHA suppressed RCC tumor cell proliferation. Cell viability and cell adhesion assays showed that HNHA induced the greatest inhibition of tumor cell proliferation in Caki-1 (A-C) and A-498 cells (D-F) Points indicate mean % of the solvent-treated control. (A, D) and (B, E) experiments were repeated at least three times with similar results. *P < 0.05 vs. Control, **P < 0.01 vs. Control, ***P < 0.005 vs. Control.
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Fig2: HNHA suppressed RCC tumor cell proliferation. Cell viability and cell adhesion assays showed that HNHA induced the greatest inhibition of tumor cell proliferation in Caki-1 (A-C) and A-498 cells (D-F) Points indicate mean % of the solvent-treated control. (A, D) and (B, E) experiments were repeated at least three times with similar results. *P < 0.05 vs. Control, **P < 0.01 vs. Control, ***P < 0.005 vs. Control.

Mentions: To investigate the effects of HNHA on histone acetylation in RCC cells, we exposed Caki-1 and A-498 cells to HNHA at various doses and then evaluated histone H3 acetylation by Western blotting. Acetylation of histone H3 was induced by HNHA in a dose-dependent manner (Figure 1A). We also assessed the effects of HNHA on the acetylation of non-histone proteins using α-tubulin; α-tubulin acetylation was also increased by HNHA in a dose-dependent manner (Figure 1A). To determine the duration of maintenance of histone H3 acetylation by HNHA, protein levels were evaluated by Western blotting at 1, 6, 24, 48, and 72 h after HNHA treatment. Histone H3 acetylation peaked at 1 h after administration of HNHA and remained stable until 48 h (Figure 2B). These data show that HNHA can induce stable acetylation of histone H3, and also non-histone proteins, in RCC cells.Figure 1


The novel histone deacetylase inhibitor, N-hydroxy-7-(2-naphthylthio) hepatonomide, exhibits potent antitumor activity due to cytochrome-c-release-mediated apoptosis in renal cell carcinoma cells.

Park KC, Heo JH, Jeon JY, Choi HJ, Jo AR, Kim SW, Kwon HJ, Hong SJ, Han KS - BMC Cancer (2015)

HNHA suppressed RCC tumor cell proliferation. Cell viability and cell adhesion assays showed that HNHA induced the greatest inhibition of tumor cell proliferation in Caki-1 (A-C) and A-498 cells (D-F) Points indicate mean % of the solvent-treated control. (A, D) and (B, E) experiments were repeated at least three times with similar results. *P < 0.05 vs. Control, **P < 0.01 vs. Control, ***P < 0.005 vs. Control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4318161&req=5

Fig2: HNHA suppressed RCC tumor cell proliferation. Cell viability and cell adhesion assays showed that HNHA induced the greatest inhibition of tumor cell proliferation in Caki-1 (A-C) and A-498 cells (D-F) Points indicate mean % of the solvent-treated control. (A, D) and (B, E) experiments were repeated at least three times with similar results. *P < 0.05 vs. Control, **P < 0.01 vs. Control, ***P < 0.005 vs. Control.
Mentions: To investigate the effects of HNHA on histone acetylation in RCC cells, we exposed Caki-1 and A-498 cells to HNHA at various doses and then evaluated histone H3 acetylation by Western blotting. Acetylation of histone H3 was induced by HNHA in a dose-dependent manner (Figure 1A). We also assessed the effects of HNHA on the acetylation of non-histone proteins using α-tubulin; α-tubulin acetylation was also increased by HNHA in a dose-dependent manner (Figure 1A). To determine the duration of maintenance of histone H3 acetylation by HNHA, protein levels were evaluated by Western blotting at 1, 6, 24, 48, and 72 h after HNHA treatment. Histone H3 acetylation peaked at 1 h after administration of HNHA and remained stable until 48 h (Figure 2B). These data show that HNHA can induce stable acetylation of histone H3, and also non-histone proteins, in RCC cells.Figure 1

Bottom Line: Renal tumors have been shown to have a higher global methylation percentage and reduced histone acetylation.An in vivo study showed that HNHA had greater anti-tumor and pro-apoptotic effects on RCC xenografts than the established HDAC inhibitors.These results suggest that HNHA may offer a new therapeutic approach to RCC.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Epigenetic modifications play a critical role in the regulation of all DNA-based processes, such as transcription, repair, and replication. Inappropriate histone modifications can result in dysregulation of cell growth, leading to neoplastic transformation and cell death. Renal tumors have been shown to have a higher global methylation percentage and reduced histone acetylation. Preclinical models have revealed that histone gene modifiers and epigenetic alterations play important roles in renal cell carcinoma (RCC) tumorigenesis. Recently, a novel HDAC inhibitor, N-hydroxy-7-(2-naphthylthio) heptanomide (HNHA), has been introduced as an example of a new class of anti-cancer agents. The anti-cancer activity of HNHA and the underlying mechanisms of action remain to be clarified.

Methods: The MTS assay using a panel of RCC cells was used to evaluate the anti-proliferative effects of HNHA. The established HDAC inhibitors, SAHA and TSA, were used for comparison. Western blotting analysis was performed to investigate the acetylation of histone H3 and the expression of apoptotic markers in vitro and in vivo. Subcellular fractionation was performed to evaluate expression of Bax and cytochrome c in the cytosol and mitochondria, and also translocation of cytochrome c from the cytoplasm to the nucleus. A confocal microscopic evaluation was performed to confirm inhibition of cell proliferation, induction of apoptosis, and the nuclear translocation of cytochrome c in RCC cells.

Results: In this study, we investigated the apoptosis-inducing activity of HNHA in cultured kidney cancer cells. Apoptosis in the HNHA-treated group was induced significantly, with marked caspase activation and Bcl-2 suppression in RCC cells in vitro and in vivo. HNHA treatment caused cytochrome c release from mitochondria, which was mediated by increased Bax expression and caspase activation. HNHA also induced nuclear translocation of cytochrome c, suggesting that HNHA can induce caspase-independent nuclear apoptosis in RCC cells. An in vivo study showed that HNHA had greater anti-tumor and pro-apoptotic effects on RCC xenografts than the established HDAC inhibitors.

Conclusions: HNHA has more potent anti-tumor activity than established HDAC inhibitors. Its activities are mediated by caspase-dependent and cytochrome-c-mediated apoptosis in RCC cells. These results suggest that HNHA may offer a new therapeutic approach to RCC.

Show MeSH
Related in: MedlinePlus