Contributions
Abstract: PB1658
Type: Publication Only
Background
Neddylation, mediated by an ubiquitin-like molecule, Nedd8 (neural precursor cell expressed
developmentally down-regulated 8), plays an important role in the regulation of protein function
turnover. The role of neddylation of histone deacetylase 1 (HDAC1) in drug resistance of acute
myelogenous leukemia (AML) cells remains unclear.
Aims
This study aimed to investigate the function and mechanism of neddylation of HDAC1 underlying drug resistance of AML cells.
Methods
The expression of HDACs (HDAC1–11) in five cases of refractory AML was compared to that of five cases of remission AML. In the attempt of identify the main role of HDAC1 in the drug resistance of AML, the nondrug-resistant AML cell lines (HL-60 and K562) and primary BMCs of remission AML patients were transfected with pcDNA-HDAC1 to stably express HDAC1. The effects of HDAC1 on the ADM resistance of AML cells were assessed by the cell viability, apoptosis and ADM-releasing index. Next, we knocked down HDAC1 via the specific RNAi sequence for HDAC1 in HL-60/ADM,
K562/A02, and primary BMCs of refractory AML patients and examined the effect of HDAC1
silencing on ADM resistance. To detect the potential mechanism underlying the higher level of HDAC1 in drug-resistant AML cells, we first compared the differential expression of HDAC1 in nondrug-resistant AML cells and drug-resistant AML cells incubated with cyclohexane (CHX), a protein synthesis inhibitor. We next sought to determine the mechanism in the degradation inhibition of HDAC1 protein in drug-resistant AML cells. Finally, an AML cell xenograft mouse model was established and used to evaluate the effect of HDAC1 on the tumor growth in the presence of ADM and Farydak treatment.
Results
The results showed that HDAC1 was significantly upregulated in refractory AML patients, as well as in
drug-resistant AML cells (HL-60/ADM and K562/A02). Intracellular HDAC1 expression promoted adriamycin (ADM) resistance of HL-60, K562, and primary bone marrow cells (BMCs) of remission AML patients as shown by increasing cell viability and ADM-releasing index, inhibiting cell apoptosis. Moreover, HDAC1 protein level in AML cells was regulated by the Nedd8-mediated neddylation and ubiquitination, which further promoted HDAC1 degradation. In vivo, HDAC1 overexpression significantly increased ADM resistance; while HDACs inhibitor Farydak markedly improved the inhibitory effect of ADM on tumor growth. Furthermore, HDAC1 silencing by Farydak and/or lentivirus mediated RNA interference against HDAC1 effectively reduced ADM resistance, resulting in the inhibition of tumor growth in AML bearing mice.
Conclusion
In summary, our findings suggested that HDAC1 contributed to the multidrug resistance of AML and its function turnover was regulated, at least in part, by epigenetic modifications, including neddylation and ubiquitination.
Session topic: 3. Acute myeloid leukemia - Biology & Translational Research
Keyword(s): AML, Drug resistance, HDAC inhibitor
Abstract: PB1658
Type: Publication Only
Background
Neddylation, mediated by an ubiquitin-like molecule, Nedd8 (neural precursor cell expressed
developmentally down-regulated 8), plays an important role in the regulation of protein function
turnover. The role of neddylation of histone deacetylase 1 (HDAC1) in drug resistance of acute
myelogenous leukemia (AML) cells remains unclear.
Aims
This study aimed to investigate the function and mechanism of neddylation of HDAC1 underlying drug resistance of AML cells.
Methods
The expression of HDACs (HDAC1–11) in five cases of refractory AML was compared to that of five cases of remission AML. In the attempt of identify the main role of HDAC1 in the drug resistance of AML, the nondrug-resistant AML cell lines (HL-60 and K562) and primary BMCs of remission AML patients were transfected with pcDNA-HDAC1 to stably express HDAC1. The effects of HDAC1 on the ADM resistance of AML cells were assessed by the cell viability, apoptosis and ADM-releasing index. Next, we knocked down HDAC1 via the specific RNAi sequence for HDAC1 in HL-60/ADM,
K562/A02, and primary BMCs of refractory AML patients and examined the effect of HDAC1
silencing on ADM resistance. To detect the potential mechanism underlying the higher level of HDAC1 in drug-resistant AML cells, we first compared the differential expression of HDAC1 in nondrug-resistant AML cells and drug-resistant AML cells incubated with cyclohexane (CHX), a protein synthesis inhibitor. We next sought to determine the mechanism in the degradation inhibition of HDAC1 protein in drug-resistant AML cells. Finally, an AML cell xenograft mouse model was established and used to evaluate the effect of HDAC1 on the tumor growth in the presence of ADM and Farydak treatment.
Results
The results showed that HDAC1 was significantly upregulated in refractory AML patients, as well as in
drug-resistant AML cells (HL-60/ADM and K562/A02). Intracellular HDAC1 expression promoted adriamycin (ADM) resistance of HL-60, K562, and primary bone marrow cells (BMCs) of remission AML patients as shown by increasing cell viability and ADM-releasing index, inhibiting cell apoptosis. Moreover, HDAC1 protein level in AML cells was regulated by the Nedd8-mediated neddylation and ubiquitination, which further promoted HDAC1 degradation. In vivo, HDAC1 overexpression significantly increased ADM resistance; while HDACs inhibitor Farydak markedly improved the inhibitory effect of ADM on tumor growth. Furthermore, HDAC1 silencing by Farydak and/or lentivirus mediated RNA interference against HDAC1 effectively reduced ADM resistance, resulting in the inhibition of tumor growth in AML bearing mice.
Conclusion
In summary, our findings suggested that HDAC1 contributed to the multidrug resistance of AML and its function turnover was regulated, at least in part, by epigenetic modifications, including neddylation and ubiquitination.
Session topic: 3. Acute myeloid leukemia - Biology & Translational Research
Keyword(s): AML, Drug resistance, HDAC inhibitor