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.

Enhancer looping protein LDB1 modulates MYB expression in T-ALL cell lines in vitro by cooperating with master transcription factors.

BACKGROUND: Despite significant progress in the prognosis of pediatric T-cell acute lymphoblastic leukemia (T-ALL) in recent decades, a notable portion of children still confronts challenges such as treatment resistance and recurrence, leading to limited options and a poor prognosis. LIM domain-binding protein 1 (LDB1) has been confirmed to exert a crucial role in various physiological and pathological processes. In our research, we aim to elucidate the underlying function and mechanisms of LDB1 within the background of T-ALL. METHODS: Employing short hairpin RNA (shRNA) techniques, we delineated the functional impact of LDB1 in T-ALL cell lines. Through the application of RNA-Seq, CUT&Tag, and immunoprecipitation assays, we scrutinized master transcription factors cooperating with LDB1 and identified downstream targets under LDB1 regulation. RESULTS: LDB1 emerges as a critical transcription factor co-activator in cell lines derived from T-ALL. It primarily collaborates with master transcription factors (ERG, ETV6, IRF1) to cooperatively regulate the transcription of downstream target genes. Both in vitro and in vivo experiments affirm the essential fuction of LDB1 in the proliferation and survival of cell lines derived from T-ALL, with MYB identified as a significant downstream target of LDB1. CONCLUSIONS: To sum up, our research establishes the pivotal fuction of LDB1 in the tumorigenesis and progression of T-ALL cell lines. Mechanistic insights reveal that LDB1 cooperates with ERG, ETV6, and IRF1 to modulate the expression of downstream effector genes. Furthermore, LDB1 controls MYB through remote enhancer modulation, providing valuable mechanistic insights into its involvement in the progression of T-ALL.

The BRD4 Inhibitor dBET57 Exerts Anticancer Effects by Targeting Superenhancer-Related Genes in Neuroblastoma.

Neuroblastoma (NB) is the most common solid tumor of the neural crest cell origin in children and has a poor prognosis in high-risk patients. The oncogene MYCN was found to be amplified at extremely high levels in approximately 20% of neuroblastoma cases. In recent years, research on the targeted hydrolysis of BRD4 to indirectly inhibit the transcription of the MYCN created by proteolysis targeting chimaera (PROTAC) technology has become very popular. dBET57 (S0137, Selleck, TX, USA) is a novel and potent heterobifunctional small molecule degrader based on PROTAC technology. The purpose of this study was to investigate the therapeutic effect of dBET57 in NB and its potential mechanism. In this study, we found that dBET57 can target BRD4 ubiquitination and disrupt the proliferation ability of NB cells. At the same time, dBET57 can also induce apoptosis, cell cycle arrest, and decrease migration. Furthermore, dBET57 also has a strong antiproliferation function in xenograft tumor models in vivo. In terms of mechanism, dBET57 targets the BET protein family and the MYCN protein family by associating with CRBN and destroys the SE landscape of NB cells. Combined with RNA-seq and ChIP-seq public database analysis, we identified the superenhancer-related genes TBX3 and ZMYND8 in NB as potential downstream targets of dBET57 and experimentally verified that they play an important role in the occurrence and development of NB. In conclusion, these results suggest that dBET57 may be an effective new therapeutic drug for the treatment of NB.

Super-enhancer-associated INSM2 regulates lipid metabolism by modulating mTOR signaling pathway in neuroblastoma.

BACKGROUND: Abnormal lipid metabolism is one of the most prominent metabolic changes in cancer. Studies have shown that lipid metabolism also plays an important role in neuroblastoma. We recently discovered that the insulinoma-associated 2 gene (INSM2) could regulate lipid metabolism in neuroblastoma (NB) and is improperly controlled by super enhancers, a mammalian genome region that has been shown to control the expression of NB cell identity genes. However, the specific molecular pathways by which INSM2 leads to NB disease development are unknown. RESULTS: We identified INSM2 as a gene regulated by super enhancers in NB. In addition, INSM2 expression levels were significantly upregulated in NB and correlated with poor prognosis in patients. We found that INSM2 drives the growth of NB cell lines both in vitro and in vivo. Knocking down INSM2 inhibited fatty acid metabolism in NB cells. Mechanistically, INSM2 regulates the expression of SREBP1 by regulating the mTOR signaling pathway, which in turn affects lipid metabolism, thereby mediating the occurrence and development of neuroblastoma. CONCLUSION: INSM2 as a super-enhancer-associated gene could regulates lipid metabolism by modulating mTOR signaling pathway in neuroblastoma.

BRD4 inhibitor GNE987 exerts anti-cancer effects by targeting super-enhancers in neuroblastoma.

BACKGROUND: Neuroblastoma (NB) is a common extracranial malignancy with high mortality in children. Recently, super-enhancers (SEs) have been reported to play a critical role in the tumorigenesis and development of NB via regulating a wide range of oncogenes Thus, the synthesis and identification of chemical inhibitors specifically targeting SEs are of great urgency for the clinical therapy of NB. This study aimed to characterize the activity of the SEs inhibitor GNE987, which targets BRD4, in NB. RESULTS: In this study, we found that nanomolar concentrations of GNE987 markedly diminished NB cell proliferation and survival via degrading BRD4. Meanwhile, GNE987 significantly induced NB cell apoptosis and cell cycle arrest. Consistent with in vitro results, GNE987 administration (0.25 mg/kg) markedly decreased the tumor size in the xenograft model, with less toxicity, and induced similar BRD4 protein degradation to that observed in vitro. Mechanically, GNE987 led to significant downregulation of hallmark genes associated with MYC and the global disruption of the SEs landscape in NB cells. Moreover, a novel candidate oncogenic transcript, FAM163A, was identified through analysis of the RNA-seq and ChIP-seq data. FAM163A is abnormally transcribed by SEs, playing an important role in NB occurrence and development. CONCLUSION: GNE987 destroyed the abnormal transcriptional regulation of oncogenes in NB by downregulating BRD4, which could be a potential therapeutic candidate for NB.