A robust luminescent assay for screening alkyladenine DNA glycosylase inhibitors to overcome DNA repair and temozolomide drug resistance / 药物分析学报

Temozolomide(TMZ)is an anticancer agent used to treat glioblastoma,typically following radiation therapy and/or surgical resection.However,despite its effectiveness,at least 50％of patients do not respond to TMZ,which is associated with repair and/or tolerance of TMZ-induced DNA lesions.Studies have demonstrated that alkyladenine DNA glycosylase(AAG),an enzyme that triggers the base excision repair(BER)pathway by excising TMZ-induced N3-methyladenine(3meA)and N7-methylguanine le-sions,is overexpressed in glioblastoma tissues compared to normal tissues.Therefore,it is essential to develop a rapid and efficient screening method for AAG inhibitors to overcome TMZ resistance in glio-blastomas.Herein,we report a robust time-resolved photoluminescence platform for identifying AAG inhibitors with improved sensitivity compared to conventional steady-state spectroscopic methods.As a proof-of-concept,this assay was used to screen 1440 food and drug administration-approved drugs against AAG,resulting in the repurposing of sunitinib as a potential AAG inhibitor.Sunitinib restored glioblastoma(GBM)cancer cell sensitivity to TMZ,inhibited GBM cell proliferation and stem cell char-acteristics,and induced GBM cell cycle arrest.Overall,this strategy offers a new method for the rapid identification of small-molecule inhibitors of BER enzyme activities that can prevent false negatives due to a fluorescent background.

Inhibition of the CDK9-cyclin T1 protein-protein interaction as a new approach against triple-negative breast cancer

Cyclin-dependent kinase 9 (CDK9) activity is correlated with worse outcomes of triple-negative breast cancer (TNBC) patients. The heterodimer between CDK9 with cyclin T1 is essential for maintaining the active state of the kinase and targeting this protein-protein interaction (PPI) may offer promising avenues for selective CDK9 inhibition. Herein, we designed and generated a library of metal complexes bearing the 7-chloro-2-phenylquinoline CˆN ligand and tested their activity against the CDK9-cyclin T1 PPI. Complex 1 bound to CDK9 via an enthalpically-driven binding mode, leading to disruption of the CDK9-cyclin T1 interaction in vitro and in cellulo. Importantly, complex 1 showed promising anti-metastatic activity against TNBC allografts in mice and was comparably active compared to cisplatin. To our knowledge, 1 is the first CDK9-cyclin T1 PPI inhibitor with anti-metastatic activity against TNBC. Complex 1 could serve as a new platform for the future design of more efficacious kinase inhibitors against cancer, including TNBC.

A pyrene-based ratiometric fluorescent probe with a large Stokes shift for selective detection of hydrogen peroxide in living cells / 药物分析学报

Hydrogen peroxide (H2O2) plays a significant role in regulating a variety of biological processes. Dys-regulation of H2O2 can lead to various diseases. Although numerous fluorescent imaging probes for H2O2 have been reported, the development of H2O2 ratiometric fluorescent probe with large Stokes shift re-mains rather limited. Such probes have shown distinct advantages, such as minimized interference from environment and improved signal-to noise ratio. In this work, we reported a new pyrene-based com-pound Py-VPB as H2O2 fluorescent probe in vitro. The probe demonstrated ratiometric detection behavior, large Stokes shift and large emission shift. In addition, the probe showed high sensitivity and selectivity towards H2O2 in vitro. Based on these excellent properties, we successfully applied Py-VPB to the visualization of exogenous and endogenous H2O2 in living cells. Cell imaging study also showed that our probe was localized in the mitochondria. We envision that the probe can provide a useful tool for unmasking the biological roles of mitochondrial H2O2 in living systems.