In acute promyelocytic leukemia (APL), normal retinoid signaling is disrupted by an abnormal PML-RARα fusion oncoprotein, leading to a block in cell differentiation.
The performances of PML-RARα detection, including admission screening, and qualitative and quantitative detection by real-time quantitative reverse transcription PCR (RT-qPCR), were assessed based on APL simulated clinical case.
The expression of senescence-associated beta-galactosidase (SA-β-gal), cell senescence-related markers (p16, p21, and promyelocytic leukemia; PML), and a growth marker (MCM2) was immunohistochemically examined.
They are also commonly deficient for expression of ATRX protein, a repressor of ALT activity, and a component of promyelocytic leukemia nuclear bodies (PML NBs) that are required for intrinsic immunity to various viruses.
While most cases of APL harboring the PML/RARA fusion respond to all-trans retinoic acid (ATRA), some variant RARA rearrangements are ATRA insensitive.
Currently, more than 11 fusion partners of RARα have been identified, of which PML accounts for 95%, promyelocytic leukemia zinc finger (PLZF) take up2%, and the remaining are other variants.
A few cases that cannot be identified with PML-RARA by using conventional methods (karyotype analysis, FISH, and RT-PCR) involve abnormal promyelocytes that are fully in accordance with APL in morphology, cytochemistry, and immunophenotype.
This is the case for Acute Promyelocytic Leukemias (APL) where SUMOylation, and subsequent destruction, of the PML-RARα fusion oncoprotein are triggered by arsenic trioxide, which is used as front-line therapy in combination with retinoic acid to cure APL patients.
In this study, we used APL cell line NB4 or P/R and PML over-expressed 293T cells as well as HeLa cells to reveal the solubility change of P/R and PML by arsenic exposure, and further determined the fate of these insoluble proteins after the removal of arsenic.
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.
The hallmark reciprocal chromosomal translocation t(15;17) involving fusion between the retinoic acid receptor (RARα) gene and promyelocytic leukemia (PML) gene is a characteristic feature in APL which consequently results in the emergence of PML-RARα chimeric gene.
The outcome of acute promyelocytic leukemia (APL) has drastically improved following the identification of the PML-RARA oncogene as a key player in the pathogenesis of APL, and the subsequent introduction of all-trans retinoic acid (ATRA) as a therapeutic agent.
Despite the rarity of APL cases with an atypical PML/RARA fusion, our study indicates that an integrated laboratory approach, employing several diagnostic techniques is crucial to timely diagnose APL.
However, few studies have investigated whether BRD4 influenced acute promyelocytic leukemia (APL), and whether BRD4 had interaction with promyelocytic leukemia-retinoic acid receptor α (PML/RARα) fusion protein to some extent.
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.
Identifying and targeting oncogenic fusion genes have revolutionized the treatment of leukemia, such as PML-RARα fusion gene in acute promyelocytic leukemia.