Dataset Information

HDAC8 Inhibition Specifically Targets Inv(16) Acute Myeloid Leukemic Stem Cells by Restoring p53 Acetylation.

ABSTRACT: Acute myeloid leukemia (AML) is driven and sustained by leukemia stem cells (LSCs) with unlimited self-renewal capacity and resistance to chemotherapy. Mutation in the TP53 tumor suppressor is relatively rare in de novo AML; however, p53 can be regulated through post-translational mechanisms. Here, we show that p53 activity is inhibited in inv(16)(+) AML LSCs via interactions with the CBF?-SMMHC (CM) fusion protein and histone deacetylase 8 (HDAC8). HDAC8 aberrantly deacetylates p53 and promotes LSC transformation and maintenance. HDAC8 deficiency or inhibition using HDAC8-selective inhibitors (HDAC8i) effectively restores p53 acetylation and activity. Importantly, HDAC8 inhibition induces apoptosis in inv(16)(+) AML CD34(+) cells, while sparing the normal hematopoietic stem cells. Furthermore, in vivo HDAC8i administration profoundly diminishes AML propagation and abrogates leukemia-initiating capacity of both murine and patient-derived LSCs. This study elucidates an HDAC8-mediated p53-inactivating mechanism promoting LSC activity and highlights HDAC8 inhibition as a promising approach to selectively target inv(16)(+) LSCs.

SUBMITTER: Qi J

PROVIDER: S-EPMC4636961 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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HDAC8 Inhibition Specifically Targets Inv(16) Acute Myeloid Leukemic Stem Cells by Restoring p53 Acetylation.

Qi Jing J Singh Sandeep S Hua Wei-Kai WK Cai Qi Q Chao Shi-Wei SW Li Ling L Liu Hongjun H Ho Yinwei Y McDonald Tinisha T Lin Allen A Marcucci Guido G Bhatia Ravi R Huang Wei-Jan WJ Chang Chung-I CI Kuo Ya-Huei YH

Cell stem cell 20150918 5

Acute myeloid leukemia (AML) is driven and sustained by leukemia stem cells (LSCs) with unlimited self-renewal capacity and resistance to chemotherapy. Mutation in the TP53 tumor suppressor is relatively rare in de novo AML; however, p53 can be regulated through post-translational mechanisms. Here, we show that p53 activity is inhibited in inv(16)(+) AML LSCs via interactions with the CBFβ-SMMHC (CM) fusion protein and histone deacetylase 8 (HDAC8). HDAC8 aberrantly deacetylates p53 and promotes ...[more]

PMID: 26387755

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Project description:Despite recent advances in therapies including immunotherapy, patients with acute myeloid leukaemia (AML) still experience relatively poor survival rates. The Inhibition of Apoptosis (IAP) family member, survivin, also known by its gene and protein name, Baculoviral IAP Repeat Containing 5 (BIRC5), remains one of the most frequently expressed antigens across AML subtypes. To better understand its potential to act as a target for immunotherapy and a biomarker for AML survival, we examined the protein and pathways that BIRC5 interacts with using the Kyoto Encyclopedia of Genes and Genomes (KEGG), search tool for recurring instances of neighbouring genes (STRING), WEB-based Gene Set Analysis Toolkit, Bloodspot and performed a comprehensive literature review. We then analysed data from gene expression studies. These included 312 AML samples in the Microarray Innovations In Leukemia (MILE) dataset. We found a trend between above median levels of BIRC5 being associated with improved overall survival (OS) but this did not reach statistical significance (p = 0.077, Log-Rank). There was some evidence of a beneficial effect in adjusted analyses where above median levels of BIRC5 were shown to be associated with improved OS (p = 0.001) including in Core Binding Factor (CBF) patients (p = 0.03). Above median levels of BIRC5 transcript were associated with improved relapse free survival (p < 0.0001). Utilisation of a second large cDNA microarray dataset including 306 AML cases, again showed no correlation between BIRC5 levels and OS, but high expression levels of BIRC5 correlated with worse survival in inv(16) patients (p = 0.077) which was highly significant when datasets A and B were combined (p = 0.001). In addition, decreased BIRC5 expression was associated with better clinical outcome (p = 0.004) in AML patients exhibiting CBF mainly due to patients with inv(16) (p = 0.007). This study has shown that BIRC5 expression plays a role in the survival of AML patients, this association is not apparent when we examine CBF patients as a cohort, but when those with inv(16) independently indicating that those patients with inv(16) would provide interesting candidates for immunotherapies that target BIRC5.

Project description:BACKGROUND:Expression of Bcr-Abl in hematopoietic stem cells is sufficient to cause chronic myeloid leukemia (CML) and tyrosine kinase inhibitors (TKI) induce molecular remission in the majority of CML patients. However, the disease driving stem cell population is not fully targeted by TKI therapy, and leukemic stem cells (LSC) capable of re-inducing the disease can persist. Single-cell RNA-sequencing technology recently identified an enriched inflammatory gene signature with TNFα and TGFβ being activated in TKI persisting quiescent LSC. Here, we studied the effects of human TNFα antibody infliximab (IFX), which has been shown to induce anti-inflammatory effects in mice, combined with TKI treatment on LSC function. METHODS:We first performed GSEA-pathway analysis using our microarray data of murine LSK cells (lin-; Sca-1+; c-kit+) from the SCLtTA/Bcr-Abl CML transgenic mouse model. Bcr-Abl positive cell lines were generated by retroviral transduction. Clonogenic potential was assessed by CFU (colony forming unit). CML mice were treated with nilotinib or nilotinib plus infliximab, and serial transplantation experiments were performed. RESULTS:Likewise to human CML, TNFα signaling was specifically active in murine CML stem cells, and ectopic expression of Bcr-Abl in murine and human progenitor cell lines induced TNFα expression. In vitro exposure to human (IFX) or murine (MP6-XT22) TNFα antibody reduced clonogenic growth of CML cells. Interestingly, TNFα antibody treatment enhanced TKI-induced effects on immature cells in vitro. Additionally, in transplant and serial transplant experiments, using our transgenic CML mouse model, we could subsequently show that IFX therapy boosted TKI-induced effects and further reduced the proportion of malignant stem cells in vivo. CONCLUSION:TNFα signaling is induced in CML stem cells, and anti-inflammatory therapy enhances TKI-induced decline of LSC, confirming that successful targeting of persisting CML stem cells can be enhanced by addressing their malignant microenvironment simultaneously.

Dataset Information

HDAC8 Inhibition Specifically Targets Inv(16) Acute Myeloid Leukemic Stem Cells by Restoring p53 Acetylation.

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HDAC8 Inhibition Specifically Targets Inv(16) Acute Myeloid Leukemic Stem Cells by Restoring p53 Acetylation.

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