The BET inhibitor GNE-987 effectively induces anti-cancer effects in T-cell acute lymphoblastic leukemia by targeting enhancer regulated genes.

T-cell acute lymphoblastic leukemia (T-ALL) is a highly aggressive hematologic malignancy originating from T progenitor cells. It accounts for 15% of childhood and 25% of adult ALL cases. GNE-987 is a novel chimeric molecule developed using proteolysis-targeting chimeras (PROTAC) technology for targeted therapy. It consists of a potent inhibitor of the bromodomain and extraterminal (BET) protein, as well as the E3 ubiquitin ligase Von Hippel-Lindau (VHL), which enables the effective induction of proteasomal degradation of BRD4. Although GNE-987 has shown persistent inhibition of cell proliferation and apoptosis, its specific antitumor activity in T-ALL remains unclear. In this study, we aimed to investigate the molecular mechanisms underlying the antitumor effect of GNE-987 in T-ALL. To achieve this, we employed technologies including RNA sequencing (RNA-seq), chromatin immunoprecipitation sequencing (ChIP-seq) and CUT&Tag. The degradation of BET proteins, specifically BRD4, by GNE-987 has a profound impact on T-ALL cell. In in vivo experiments, sh-BRD4 lentivirus reduced T-ALL cell proliferation and invasion, extending the survival time of mice. The RNA-seq and CUT&Tag analyses provided further insights into the mechanism of action of GNE-987 in T-ALL. These analyses revealed that GNE-987 possesses the ability to suppress the expression of various genes associated with super-enhancers (SEs), including lymphoblastic leukemia 1 (LCK). By targeting these SE-associated genes, GNE-987 effectively inhibits the progression of T-ALL. Importantly, SE-related oncogenes like LCK were identified as critical targets of GNE-987. Based on these findings, GNE-987 holds promise as a potential novel candidate drug for the treatment of T-ALL.

Targeting RBM39 through indisulam induced mis-splicing of mRNA to exert anti-cancer effects in T-cell acute lymphoblastic leukemia.

BACKGROUND: Despite the use of targeted therapeutic approaches, T-cell acute lymphoblastic leukemia (T-ALL) is still associated with a high incidence of complications and a poor prognosis. Indisulam (also known as E7070), a newly identified molecular glue compound, has demonstrated increased therapeutic efficacy in several types of cancer through the rapid degradation of RBM39. This study aimed to evaluate the therapeutic potential of indisulam in T-ALL, elucidate its underlying mechanisms and explore the role of the RBM39 gene. METHODS: We verified the anticancer effects of indisulam in both in vivo and in vitro models. Additionally, the construction of RBM39-knockdown cell lines using shRNA confirmed that the malignant phenotype of T-ALL cells was dependent on RBM39. Through RNA sequencing, we identified indisulam-induced splicing anomalies, and proteomic analysis helped pinpoint protein changes caused by the drug. Comprehensive cross-analysis of these findings facilitated the identification of downstream effectors and subsequent validation of their functional roles. RESULTS: Indisulam has significant antineoplastic effects on T-ALL. It attenuates cell proliferation, promotes apoptosis and interferes with cell cycle progression in vitro while facilitating tumor remission in T-ALL in vivo models. This investigation provides evidence that the downregulation of RBM39 results in the restricted proliferation of T-ALL cells both in vitro and in vivo, suggesting that RBM39 is a potential target for T-ALL treatment. Indisulam's efficacy is attributed to its ability to induce RBM39 degradation, causing widespread aberrant splicing and abnormal translation of the critical downstream effector protein, THOC1, ultimately leading to protein depletion. Moreover, the presence of DCAF15 is regarded as critical for the effectiveness of indisulam, and its absence negates the ability of indisulam to induce the desired functional alterations. CONCLUSION: Our study revealed that indisulam, which targets RBM39 to induce tumor cell apoptosis, is an effective drug for treating T-ALL. Targeting RBM39 through indisulam leads to mis-splicing of pre-mRNAs, resulting in the loss of key effectors such as THOC1.