Small molecule targeting of FBXO21 mediated p85αubiquitylation in acute myeloid leukemia

Abstract

PI3K inhibitors that target the catalytic sub-unit p110 are used in cancer therapy to inhibit overactive PI3K signaling pathway. However, their clinical use is limited by severe adverse effects and development of resistance, highlighting the need for further research on regulation of the PI3K pathway. We have identified that FBXO21 ubiquitinates regulatory PI3K subunit p85, and silencing of FBXO21 inhibits canonical PI3K signaling. To target FBXO21, we developed a small molecule designed to interfere with substrate:ligase interaction. Our novel small molecule effectively blocks p85 ubiquitination leading to decreased PI3K pathway activation and cell death in acute myeloid leukemia (AML). Moreover, our studies demonstrate selectivity for AML cells over healthy counterparts, and elimination of AML in vivo, emphasizing FBXO21s potential as a promising therapeutic target for AML. Targeting substrate:ligase interactions provide new avenues for drug discovery that may enhance the efficacy of current therapies and benefits for improving patient outcomes. STATEMENT OF SIGNIFICANCEOur studies highlight the potential of the ubiquitin E3 ligase FBXO21 as an alternative therapeutic target for the PI3K signaling pathway, not only in AML but in cancers with aberrant PI3K signaling.