Promyelocytic leukemia-retinoic acid receptor alpha fusion protein (PML-RARA) (PML-RARA)

The Promyelocytic leukemia-retinoic acid receptor alpha (PML-RARA) fusion protein is the pathognomonic driver of Acute Promyelocytic Leukemia (APL), created by the t(15;17)(q24;q21) chromosomal translocation [1, 3]. This chimeric protein acts as a constitutive transcriptional repressor of retinoic acid-responsive genes, effectively blocking myeloid differentiation at the promyelocyte stage [2, 4]. While physiological levels of retinoic acid are insufficient to overcome this repression, pharmacological doses of all-trans retinoic acid (ATRA) bind to the RARA moiety, inducing a conformational change that promotes terminal differentiation of the malignant cells [1, 4]. Arsenic trioxide (ATO) provides a complementary therapeutic approach by binding to the PML moiety, which triggers the degradation of the fusion protein via the proteasome pathway [4]. The synergy between ATRA and ATO has revolutionized the treatment of APL, making it a highly curable malignancy [1]. Monitoring for the PML-RARA transcript is essential for diagnosis and for detecting minimal residual disease during follow-up [3]. Beyond its role in APL, the study of PML-RARA has served as a paradigm for targeted therapy in oncology, demonstrating how understanding a molecular lesion can lead to curative treatments.

Other names

PML-RAR alphat(15;17) fusion proteinPML/RARAMyeloid leukemia-associated fusion protein PML-RARA

Pharmacological doses of ATRA bind to the RARA domain, triggering the release of co-repressors and recruitment of co-activators to restore myeloid differentiation. Arsenic trioxide binds to the PML domain, inducing SUMOylation and proteasomal degradation of the fusion protein [1, 4].