7usj
BRD4-BD2 in complex with SF2523
Structural highlights
DiseaseBRD4_HUMAN Note=A chromosomal aberration involving BRD4 is found in a rare, aggressive, and lethal carcinoma arising in midline organs of young people. Translocation t(15;19)(q14;p13) with NUT which produces a BRD4-NUT fusion protein.[1] [2] FunctionBRD4_HUMAN Plays a role in a process governing chromosomal dynamics during mitosis (By similarity). Publication Abstract from PubMedMedulloblastoma (MB) is a malignant pediatric brain tumor which shows upregulation of MYC and sonic hedgehog (SHH) signaling. SHH inhibitors face acquired resistance, which is a major cause of relapse. Further, direct MYC oncogene inhibition is challenging, inhibition of MYC upstream insulin-like growth factor/ phosphatidylinositol-4,5-bisphosphate 3-kinase (IGF/PI3K) is a promising alternative. While PI3K inhibition activates resistance mechanisms, simultaneous inhibition of bromodomain-containing protein 4 (BRD4) and PI3K can overcome resistance. We synthesized a new molecule 8-(2,3-dihydrobenzo[b] [1, 4] dioxin-6-yl)-2-morpholino-4H-chromen-4-one (MDP5) that targets both BRD4 and PI3K pathways. We used X-ray crystal structures and a molecular modeling approach to confirm the interactions between MDP5 with bromo domains (BDs) from both BRD2 and BRD4, and molecular modeling for PI3K binding. MDP5 was shown to inhibit target pathways and MB cell growth in vitro and in vivo. MDP5 showed higher potency in DAOY cells (IC(50) 5.5 muM) compared to SF2523 (IC(50) 12.6 muM), and its IC(50) values in HD-MB03 cells were like SF2523. Treatment of MB cells with MDP5 significantly decreased colony formation, increased apoptosis, and halted cell cycle progression. Further, MDP5 was well tolerated in NSG mice bearing either xenograft or orthotopic MB tumors at the dose of 20 mg/kg, and significantly reduced tumor growth and prolonged animal survival. Targeting BRD4 and PI3K signaling pathways for the treatment of medulloblastoma.,Sethi B, Kumar V, Jayasinghe TD, Dong Y, Ronning DR, Zhong HA, Coulter DW, Mahato RI J Control Release. 2023 Jan 5;354:80-90. doi: 10.1016/j.jconrel.2022.12.055. PMID:36599397[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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