HDAC8 Knockout Cell Lysate

Histone deacetylase 8 (HDAC8), a class I HDAC that modifies non-histone proteins such as p53, is highly expressed in different hematological neoplasms including a subtype of acute myeloid leukemia (AML) bearing inversion of chromosome 16 [inv(16)]. To investigate HDAC8 contribution to hematopoietic stem cell maintenance and myeloid leukemic transformation, we generated a zebrafish model with Hdac8 overexpression and observed an increase in hematopoietic stem/progenitor cells, a phenotype that could be reverted using a specific HDAC8 inhibitor, PCI-34051 (PCI). In addition, we demonstrated that AML cell lines respond differently to PCI treatment: HDAC8 inhibition elicits cytotoxic effect with cell cycle arrest followed by apoptosis in THP-1 cells, and cytostatic effect in HL60 cells that lack p53. A combination of cytarabine, a standard anti-AML chemotherapeutic, with PCI resulted in a synergistic effect in all the cell lines tested. We, then, searched for a mechanism behind cell cycle arrest caused by HDAC8 inhibition in the absence of functional p53 and demonstrated an involvement of the canonical WNT signaling in zebrafish and in cell lines. Together, we provide the evidence for the role of HDAC8 in hematopoietic stem cell differentiation in zebrafish and AML cell lines, suggesting HDAC8 inhibition as a therapeutic target in hematological malignancies. Accordingly, we demonstrated the utility of a highly specific HDAC8 inhibition as a therapeutic strategy in combination with standard chemotherapy.

The Cornelia de Lange syndrome (CdLS) is a genetic disorder characterized by multisystemic malformations. CdLS is due tomutations in one of the following genes: NIPBL, SMC1A, SMC3, RAD21, and HDAC8. On the other hand, 10q11.2 deletions cause a wide range of presentations in patients. Approximately 40 cases with variable deletions of 10q11.2 have been reported in literature. Some of the reported cases involve the coexistence of duplication or deletion affecting one copy of the chromosome. However, deletion of chromosome 10q11.22-q11.23 and CdLS syndrome caused by NIPBL gene mutations have not been reported previously. This report, therefore, is the first to report their coexistence together.