Abstract
The mechanisms underlying activation of the BET pathway in AML cells remain poorly understood. We have discovered that autophagy is activated in acute leukemia cells expressing mutant nucleophosmin 1 (NPMc+) or MLL-fusion proteins. Autophagy activation results in the degradation of NPM1 and HEXIM1, two negative regulators of BET pathway activation. Inhibition of autophagy with pharmacologic inhibitors or through knocking down autophagy-related gene 5 (Atg5) expression increases the expression of both NPM1 and HEXIM1. The Brd4 inhibitors JQ1 and I-BET-151 also inhibit autophagy and increase NPM1 and HEXIM1 expression. We conclude that the degradation of NPM1 and HEXIM1 through autophagy in certain AML subsets contributes to the activation of the BET pathway in these cells.
Keywords:
AML; BET inhibitors; HEXIM1; NPM1; autophagy.
MeSH terms
-
Autophagy* / genetics
-
Cell Cycle Proteins
-
Cell Line, Tumor
-
Cell Proliferation
-
Gene Expression Regulation, Leukemic
-
Humans
-
Leukemia, Myeloid, Acute / genetics
-
Leukemia, Myeloid, Acute / metabolism*
-
Myeloid-Lymphoid Leukemia Protein / genetics
-
Myeloid-Lymphoid Leukemia Protein / metabolism
-
Nuclear Proteins / antagonists & inhibitors
-
Nuclear Proteins / genetics
-
Nuclear Proteins / metabolism*
-
Nucleophosmin
-
Oncogene Proteins, Fusion / genetics
-
Oncogene Proteins, Fusion / metabolism
-
Protein Transport
-
Proteins / antagonists & inhibitors*
-
Proteolysis
-
RNA-Binding Proteins / genetics
-
RNA-Binding Proteins / metabolism*
-
Signal Transduction
-
Transcription Factors / antagonists & inhibitors
Substances
-
BRD4 protein, human
-
Cell Cycle Proteins
-
HEXIM1 protein, human
-
NPM1 protein, human
-
Nuclear Proteins
-
Oncogene Proteins, Fusion
-
Proteins
-
RNA-Binding Proteins
-
Transcription Factors
-
bromodomain and extra-terminal domain protein, human
-
Nucleophosmin
-
Myeloid-Lymphoid Leukemia Protein