Facilitated Drug Repurposing with Artemisinin-Derived PROTACs: Unveiling PCLAF as a Therapeutic Target.

Artemisinin, a prominent anti-malaria drug, is being investigated for its potential as a repurposed cancer treatment. However, its effectiveness in tumor cell lines remains limited, and its mechanism of action is unclear. To make more progress, the PROteolysis-TArgeting chimera (PROTAC) technique has been applied to design and synthesize novel artemisinin derivatives in this study. Among them, AD4, the most potent compound, exhibited an IC50 value of 50.6 nM in RS4;11 cells, over 12-fold better than that of its parent compound, SM1044. This was supported by prolonged survival of RS4;11-transplanted NOD/SCID mice. Meanwhile, AD4 effectively degraded PCLAF in RS4;11 cells and thus activated the p21/Rb axis to exert antitumor activity by directly targeting PCLAF. The discovery of AD4 highlights the great potential of using PROTACs to improve the efficacy of natural products, identify therapeutic targets, and facilitate drug repurposing. This opens a promising avenue for transforming other natural products into effective therapies.

NRSF deficiency leads to abnormal postnatal development of dentate gyrus and impairment of progenitors in subgranular zone of hippocampus.

Neuron-restrictive silencing factor (NRSF) is a zinc-finger transcription factor that regulates expression of a diverse set of genes. However, NRSF function in brain development still remains elusive. In the present study, we generated NRSF-conditional knockout (NRSF-cKO) mice by hGFAP-Cre/loxp system to study the effect of NRSF deficiency on brain development. Results showed that NRSF conditional knockout caused a smaller hippocampus and a thinner granule cell layer (GCL) in mice. Moreover, the reduction and disarrangement of GFAP+ cells in subgranular zone (SGZ) of NRSF-cKO mice was accompanied with the decreased number of premature neurons, neural stem cells (NSCs) and neural progenitor cells (NPCs), as well as compromising the majority of mitotically active cells. The analysis of postnatal development of hippocampus indicated the existence of an abnormality at postnatal day (P) 8, rather than at P1, in NRSF-cKO mice, although the densities of Ki67+ cells with mitotic ability in dentate gyrus were relatively unaffected at P1 and P8. Meanwhile, NRSF deficiency led to abnormal organization of SGZ at P8 during postnatal development. RNA-Seq analysis revealed 79 deregulated genes in hippocampus of NRSF-cKO mice at P8, which were involved in p53 signal transduction, neuron migration and negative regulation of cell proliferation, etc. The deregulation of p53 pathway in NRSF-cKO mice at P1 and P8 was evidenced, of which p21/Cdkn1a was accumulated in a portion of NSCs and NPCs in hippocampus during postnatal development. Together, these results, for the first time, revealed that NRSF could significantly influence the postnatal development of hippocampus, especially the formation of SGZ.