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Design and Evaluation of Tumor-Specific Dendrimer Epigenetic Therapeutics.

Zong H, Shah D, Selwa K, Tsuchida RE, Rattan R, Mohan J, Stein AB, Otis JB, Goonewardena SN - ChemistryOpen (2015)

Bottom Line: Here we report the design and evaluation of tumor-specific dendrimer-HDACi conjugates.The HDACi was conjugated to the dendrimer using an ester linkage through its hydroxamic acid group, inactivating the HDACi until it is released from the dendrimer.Furthermore, we demonstrate that unlike traditional HDACi, dendrimer-HDACi conjugates do not affect tumor-associated macrophages, a recently recognized mechanism through which drug resistance emerges.

View Article: PubMed Central - PubMed

Affiliation: Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan, Room 9220C MSRBIII 1150 W. Medical Center Drive, Ann Arbor, MI, 48109, USA).

ABSTRACT
Histone deacetylase inhibitors (HDACi) are promising therapeutics for cancer. HDACi alter the epigenetic state of tumors and provide a unique approach to treat cancer. Although studies with HDACi have shown promise in some cancers, variable efficacy and off-target effects have limited their use. To overcome some of the challenges of traditional HDACi, we sought to use a tumor-specific dendrimer scaffold to deliver HDACi directly to cancer cells. Here we report the design and evaluation of tumor-specific dendrimer-HDACi conjugates. The HDACi was conjugated to the dendrimer using an ester linkage through its hydroxamic acid group, inactivating the HDACi until it is released from the dendrimer. Using a cancer cell model, we demonstrate the functionality of the tumor-specific dendrimer-HDACi conjugates. Furthermore, we demonstrate that unlike traditional HDACi, dendrimer-HDACi conjugates do not affect tumor-associated macrophages, a recently recognized mechanism through which drug resistance emerges. We anticipate that this new class of cell-specific epigenetic therapeutics will have tremendous potential in the treatment of cancer.

No MeSH data available.


Related in: MedlinePlus

Biological evaluation of linker-modified SAHA. a) Apoptosis index demonstrating apoptosis induction with free SAHA and the ester-modified SAHA. The amide-modified SAHA did not demonstrate any evidence of apoptosis at the time points and concentrations tested. KB cells were incubated with 100 nm of the linker-modified SAHA compounds and free SAHA for 24 h. Values represent the mean ± S.E.M. for n=3 independent experiments. b) Protein immunoblots demonstrate that both free SAHA and eSAHA induce hyperacetylation of histones consistent with their known epigenetic mechanism of action. In agreement with the apoptosis data, the amide-modified SAHA compound did not demonstrate any hyperacetylation of histones. KB cells were incubated with 10 μm of the SAHA compounds 2 h and cell lysates were collected. Total ERK was used as the protein loading control.
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fig01: Biological evaluation of linker-modified SAHA. a) Apoptosis index demonstrating apoptosis induction with free SAHA and the ester-modified SAHA. The amide-modified SAHA did not demonstrate any evidence of apoptosis at the time points and concentrations tested. KB cells were incubated with 100 nm of the linker-modified SAHA compounds and free SAHA for 24 h. Values represent the mean ± S.E.M. for n=3 independent experiments. b) Protein immunoblots demonstrate that both free SAHA and eSAHA induce hyperacetylation of histones consistent with their known epigenetic mechanism of action. In agreement with the apoptosis data, the amide-modified SAHA compound did not demonstrate any hyperacetylation of histones. KB cells were incubated with 10 μm of the SAHA compounds 2 h and cell lysates were collected. Total ERK was used as the protein loading control.

Mentions: To evaluate the functionality of the linker-modified SAHA compounds, we used the annexin V/7-aminoactinomycin D (An/7AAD) apoptosis assay and the folate-receptor-overexpressing KB human cancer cell line. KB cells were incubated with 100 nm of the linker-modified SAHA compounds 1 or 2 or free SAHA. After 24 h, the cells treated with the ester-linker-modified SAHA (SAHA-eAzide 1) and free SAHA had evidence of apoptosis, while the amide-linker-modified SAHA (SAHA-aAzide 2) did not show any evidence of apoptosis (Figure 1). To verify that the KB cell apoptosis was due to alteration of histones, we probed for histone acetylation using protein immunoblotting. We found that free SAHA and the SAHA-eAzide 1 not only increased apoptosis, but also induced hyperacetylation of histones confirming that SAHA-eAzide 1 was still active (Figure 1). In contrast, the amide-modified SAHA (SAHA-aAzide 2) did not induce apoptosis or histone hyperacetylation, suggesting that this modification inactivated the SAHA molecule.


Design and Evaluation of Tumor-Specific Dendrimer Epigenetic Therapeutics.

Zong H, Shah D, Selwa K, Tsuchida RE, Rattan R, Mohan J, Stein AB, Otis JB, Goonewardena SN - ChemistryOpen (2015)

Biological evaluation of linker-modified SAHA. a) Apoptosis index demonstrating apoptosis induction with free SAHA and the ester-modified SAHA. The amide-modified SAHA did not demonstrate any evidence of apoptosis at the time points and concentrations tested. KB cells were incubated with 100 nm of the linker-modified SAHA compounds and free SAHA for 24 h. Values represent the mean ± S.E.M. for n=3 independent experiments. b) Protein immunoblots demonstrate that both free SAHA and eSAHA induce hyperacetylation of histones consistent with their known epigenetic mechanism of action. In agreement with the apoptosis data, the amide-modified SAHA compound did not demonstrate any hyperacetylation of histones. KB cells were incubated with 10 μm of the SAHA compounds 2 h and cell lysates were collected. Total ERK was used as the protein loading control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4522184&req=5

fig01: Biological evaluation of linker-modified SAHA. a) Apoptosis index demonstrating apoptosis induction with free SAHA and the ester-modified SAHA. The amide-modified SAHA did not demonstrate any evidence of apoptosis at the time points and concentrations tested. KB cells were incubated with 100 nm of the linker-modified SAHA compounds and free SAHA for 24 h. Values represent the mean ± S.E.M. for n=3 independent experiments. b) Protein immunoblots demonstrate that both free SAHA and eSAHA induce hyperacetylation of histones consistent with their known epigenetic mechanism of action. In agreement with the apoptosis data, the amide-modified SAHA compound did not demonstrate any hyperacetylation of histones. KB cells were incubated with 10 μm of the SAHA compounds 2 h and cell lysates were collected. Total ERK was used as the protein loading control.
Mentions: To evaluate the functionality of the linker-modified SAHA compounds, we used the annexin V/7-aminoactinomycin D (An/7AAD) apoptosis assay and the folate-receptor-overexpressing KB human cancer cell line. KB cells were incubated with 100 nm of the linker-modified SAHA compounds 1 or 2 or free SAHA. After 24 h, the cells treated with the ester-linker-modified SAHA (SAHA-eAzide 1) and free SAHA had evidence of apoptosis, while the amide-linker-modified SAHA (SAHA-aAzide 2) did not show any evidence of apoptosis (Figure 1). To verify that the KB cell apoptosis was due to alteration of histones, we probed for histone acetylation using protein immunoblotting. We found that free SAHA and the SAHA-eAzide 1 not only increased apoptosis, but also induced hyperacetylation of histones confirming that SAHA-eAzide 1 was still active (Figure 1). In contrast, the amide-modified SAHA (SAHA-aAzide 2) did not induce apoptosis or histone hyperacetylation, suggesting that this modification inactivated the SAHA molecule.

Bottom Line: Here we report the design and evaluation of tumor-specific dendrimer-HDACi conjugates.The HDACi was conjugated to the dendrimer using an ester linkage through its hydroxamic acid group, inactivating the HDACi until it is released from the dendrimer.Furthermore, we demonstrate that unlike traditional HDACi, dendrimer-HDACi conjugates do not affect tumor-associated macrophages, a recently recognized mechanism through which drug resistance emerges.

View Article: PubMed Central - PubMed

Affiliation: Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan, Room 9220C MSRBIII 1150 W. Medical Center Drive, Ann Arbor, MI, 48109, USA).

ABSTRACT
Histone deacetylase inhibitors (HDACi) are promising therapeutics for cancer. HDACi alter the epigenetic state of tumors and provide a unique approach to treat cancer. Although studies with HDACi have shown promise in some cancers, variable efficacy and off-target effects have limited their use. To overcome some of the challenges of traditional HDACi, we sought to use a tumor-specific dendrimer scaffold to deliver HDACi directly to cancer cells. Here we report the design and evaluation of tumor-specific dendrimer-HDACi conjugates. The HDACi was conjugated to the dendrimer using an ester linkage through its hydroxamic acid group, inactivating the HDACi until it is released from the dendrimer. Using a cancer cell model, we demonstrate the functionality of the tumor-specific dendrimer-HDACi conjugates. Furthermore, we demonstrate that unlike traditional HDACi, dendrimer-HDACi conjugates do not affect tumor-associated macrophages, a recently recognized mechanism through which drug resistance emerges. We anticipate that this new class of cell-specific epigenetic therapeutics will have tremendous potential in the treatment of cancer.

No MeSH data available.


Related in: MedlinePlus