**Background**
Leukemia is a malignant cancer of the blood and bone marrow characterized by the uncontrolled proliferation of abnormal white blood cells. Splicing factor mutations are frequently observed in various types of leukemia and play a critical role in the pathogenesis and progression of the disease. Among these, the U2 auxiliary factor 1 (U2AF1) is a key component of the spliceosome, and its homology motif (UHM) is essential for protein-protein interactions that regulate pre-mRNA splicing. Targeting the U2AF1-UHM domain presents a promising therapeutic strategy, particularly for cell lines carrying splicing factor mutations. In this context, we will introduce a selective U2AF1-UHM inhibitor – AP232.
**Definition**
AP232 dihydrochloride is a selective U2AF1-UHM inhibitor with an IC50 value of 7.96 μM. According to the AP232 description, this compound exhibits 2.8-24-fold selectivity against other UHM-containing proteins.
**In Vitro Studies**
The AP232 biological activity has been extensively evaluated in various leukemia models. In vitro studies demonstrated that AP232 dihydrochloride inhibits the U2 auxiliary factor homology motif of U2AF1 (U2AF1-UHM) with an IC50 of 7.96 μM, showing selectivity over RBM39-UHM, SPF45-UHM, PUF60-UHM, and U2AF2-UHM. In K562 cells, AP232 (40 μM) stabilizes endogenous full-length U2AF1 and reduces its sensitivity to Pronase. Furthermore, AP232 (72 h) inhibits cell growth across six leukemia cell lines, including MV4-11, NKM-1, K562, MOLM13, HNT-34, and MONO-MAC1.
Regarding cell cycle regulation, AP232 (5-30 μM; 24-48 h) disrupts the cell cycle of leukemia cells. Specifically, in NKM-1 cells, it increased the G2/M phase ratio at 48 h. In K562 cells, treatment at 24 h reduced the S phase and increased the sub-G1 phase, while treatment at 48 h increased the G1 phase and reduced the S and G2/M phases. Additionally, AP232 (20 μM; 2 h) reduces the proportion of functional lysosomes in NKM-1, K562, and MV4-11 cells. Notably, AP232 (10-30 μM; 48 h) inhibits AP232 autophagy in NKM-1 and K562 cells and impairs lysosome acidification. In conclusion, AP232 is a selective U2AF1-UHM inhibitor that exerts potent anti-leukemia activity by inducing cell cycle arrest and inhibiting autophagy.
Keywords
AP232, AP 232, AP-232, DNA/RNA Synthesis, Autophagy, U2AF1, UHM, Leukemia, Lysosome, MV4-11, NKM-1, K562, MOLM13, HNT-34, MONO-MAC1
References