Arsenic trioxide (ATO) is another anti-cancer agent that promotes autophagy-dependent clearance of promyelocytic leukemiaretinoic acid receptor alpha gene (PML-RARα) in APL cells.
Acute promyelocytic leukemia (APL) is a distinct type of acute myeloid leukemia that is defined by the presence of the translocations that mostly involve the RARA gene.
Here, we report NPM1 as a new partner gene of RARG and identify a unique NPM1-RARG-NPM1 chimeric fusion for the first time in an old male with morphological and immunophenotypical features of hypergranular APL but lacking response to all-trans retinoic acid (ATRA) and arsenic trioxide (As<sub>2</sub>O<sub>3</sub>) therapy.
Acute promyelocytic leukemia (APL) is characterized by a reciprocal translocation between chromosomes 15 and 17, t(15;17), resulting in the expression of PML-RARα fusion protein, which disrupts the normal PML nuclear bodies (PML-NBs) to micro-speckled pattern, leading to loss of their original functions.
<i>TBL1XR1-RARB</i> as an oncogenic protein exerts effects similar to those of <i>PML-RARA</i>, underpinning the importance of retinoic acid pathway alterations in the pathogenesis of APL.<b>Significance:</b> These findings report a novel and distinct genetic subtype of acute promyelocytic leukemia (APL) by illustrating that the majority of APL without RARA translocations harbor RARB translocations.<i></i>.
Mutation analysis of PML-RARA was performed using samples from a chemotherapy- and ATRA-resistant APL patient, and the frequencies of mutated PML-RARA transcript were analyzed by targeted deep sequencing.
Of 84 cases (63%) that lacked monocytic differentiation ("myeloid AML"), 40 (48%) demonstrated an acute promyelocytic leukemia-like (APL-like) immunophenotype by flow cytometry, with absence of CD34 and HLA-DR and strong myeloperoxidase expression, in the absence of a PML-RARA translocation.
Furthermore, crocetin suppressed the expression of clinical marker promyelocytic leukemia/retinoic acid receptor-α ( PML/RARα) in NB4 and primary APL cells, and reduced the expression of histone deacetylase 1 ( HDAC1) in all leukemic cells.
Human acute promyelocytic leukemia (APL) cells are characterized by the arrest of differentiation at the promyelocytic stage due to epigenetic perturbations induced by PML/RARα fusion protein (Promyelocytic Leukemia protein - PML/Retinoic Acid Receptor alpha - RARα).
We hypothesize a novel mechanism of EZH2 function alteration, which may be responsible for an acute myeloid leukemia with APL-like phenotype featuring dysregulation of the RARA and RARG genes.
Identifying and targeting oncogenic fusion genes have revolutionized the treatment of leukemia, such as PML-RARα fusion gene in acute promyelocytic leukemia.
We present a case of an 18-year-old female who was diagnosed with AML (FLT3 (Fms like tyrosine kinase 3) and PML-RARA (promyelocytic leukemia-retinoic acid receptor alpha) translocation-negative) and after initial treatment with a standard induction regimen of cytarabine and daunorubicin (3+7 regimen), her bone marrow showed blast cells less than 5% and dense aggregates/sheets of atypical/immature mast cells with immunohistochemical stain CD117+ve and toluidine blue positive in mast cell aggregates.
To understand the relationship between PML/RARα and the oncogene in the development of APL, we investigate the regulation mechanism of PML/RARα to MYB proto-oncogene and the role of this regulation on the proliferation and differentiation of APL cells.
The As2O3-mediated degradation of PML-RARA (promyelocytic leukemia-retinoic acid receptor-α) oncoprotein via the proteasome pathway appears to be critical for such distinguished sensitivity.
Importantly, miR-10a overexpression was significantly associated with FAB-M3/t(15;17) subtypes and NPM1 mutation, meanwhile, overexpression of miR-10b was correlated with NPM1 and DNMT3A mutations.