Genome-wide CRISPR screens identify an RXR-MYLIP-LDLR axis regulating BH3 mimetic sensitivity in peripheral T-cell lymphomas.

BH3 mimetics are a promising class of drugs in hematologic malignancies, but their efficacy in peripheral T-cell lymphoma (PTCL) remains poorly understood. To identify genetic determinants of BH3 mimetic response, we performed a genome-wide CRISPR-Cas9 knockout screen in PTCL cell lines and identified MYLIP, an E3 ubiquitin ligase targeting the LDL receptor (LDLR), as a novel sensitizer to navitoclax. MYLIP deletion enhanced the cytotoxicity of navitoclax, venetoclax, and the BCL-XL-selective degrader DT2216 across multiple PTCL models. Mechanistically, MYLIP loss increased LDLR expression, promoted cholesterol uptake, and elevated apoptotic priming. Recombinant PCSK9, which facilitates LDLR degradation, reversed MYLIP knockout-induced sensitization, establishing a functional role for LDLR in BH3 mimetic response. We also identified the nuclear receptor RXRB as an upstream regulator of MYLIP; dual RXRA/RXRB depletion more effectively suppressed MYLIP, upregulated LDLR, and potentiated navitoclax cytotoxicity. In vivo, MYLIP-deficient xenografts showed enhanced tumor suppression with navitoclax treatment. Transcriptomic analyses of primary PTCL samples revealed reduced MYLIP expression in ALK-positive anaplastic large cell lymphoma and genetically defined subsets of nodal T follicular helper cell lymphomas. These findings uncover an RXR-MYLIP-LDLR axis that links cholesterol metabolism to apoptotic susceptibility, offering mechanistic insight into BH3 mimetic sensitivity in PTCL.