Transcriptional modulation using HDACi depsipeptide promotes immune cell-mediated tumor destruction of murine B16
Takashi Murakami1, Atsuko Sato, Nicole A L Chun
1Division of Organ Replacement Research, Center for Molecular Medicine, Jichi Medical University, Shimotuke, Tochigi, Japan. takmu@jichi.ac.jp
Abstract:
With melanoma, as with many other malignancies, aberrant transcriptional repression is a hallmark of refractory cancer. To restore gene expression, use of a histone deacetylase inhibitor (HDACi) is expected to be effective. Our recent DNA micro-array analysis showed that the HDACi depsipeptide (FK228) significantly enhances gp100 antigen expression. Herein, we demonstrate that depsipeptide promotes tumor-specific T-cell-mediated killing of B16/F10 murine melanoma cells. First, by a quantitative assay of caspase-3/7 activity, a sublethal dose of depsipeptide was determined (ED50: 5 nM), in which p21(Waf1/Cip1) and Fas were sufficiently evoked concomitantly with histone H3 acetylation. Second, the sublethal dose of depsipeptide treatment with either a recombinant Fas ligand or tumor-specific T cells synergistically enhanced apoptotic cell death in B16/F10 cells in vitro. Furthermore, we found that depsipeptide increased levels of perforin in T cells. Finally, in vivo metastatic growth of B16/F10 in the lung was significantly inhibited by a combination of depsipeptide treatment and immune cell adoptive transfer from immunized mice using irradiated B16 cells and gp100-specific (Pmel-1) TCR transgenic mice (P<0.05, vs cell transfer alone). Consequently, employment of a transcriptional modulation strategy using HDACis might prove to be a useful pretreatment for human melanoma immunotherapy.
Insights
Histone deacetylase inhibitors (HDACis) like depsipeptide can enhance melanoma antigen expression. This pretreatment strategy, combined with immunotherapy, shows promise for improving T-cell-mediated killing of melanoma cells.
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- Aberrant transcriptional repression is common in refractory melanoma.
- Histone deacetylase inhibitors (HDACis) can restore gene expression.
- Depsipeptide (FK228), an HDACi, enhances gp100 antigen expression in melanoma.
Purpose of the Study:
- To investigate the efficacy of depsipeptide in enhancing anti-melanoma immune responses.
- To determine the optimal sublethal dose of depsipeptide for B16/F10 melanoma cells.
- To evaluate the synergistic effects of depsipeptide with T-cell-mediated killing and immunotherapy.
Main Methods:
- Determined sublethal depsipeptide dose (ED50: 5 nM) via caspase-3/7 activity assay.
- Assessed histone H3 acetylation, p21(Waf1/Cip1), and Fas induction.
- Evaluated synergistic apoptosis induction with Fas ligand or T cells in vitro.
- Measured perforin levels in T cells.
- Assessed in vivo inhibition of B16/F10 lung metastasis using combined depsipeptide and adoptive T-cell transfer.
Main Results:
- A sublethal dose of depsipeptide induced p21(Waf1/Cip1) and Fas, with histone H3 acetylation.
- Depsipeptide synergistically enhanced apoptotic cell death in B16/F10 cells when combined with Fas ligand or T cells.
- Depsipeptide treatment increased perforin levels in T cells.
- Combined depsipeptide treatment and adoptive T-cell transfer significantly inhibited B16/F10 lung metastasis in vivo.
Conclusions:
- Depsipeptide enhances tumor-specific T-cell-mediated killing of melanoma cells.
- Transcriptional modulation using HDACis may serve as a valuable pretreatment for melanoma immunotherapy.
- This strategy holds potential for improving outcomes in human melanoma treatment.
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