Aptamer-Based Cell-Surface Profiling with Single-Cell Resolution Enables Precise Cancer Characterization

Molecular profiling of cell-surface proteins is a powerful strategy for precise cancer diagnosis.While mass cytometry(MC)enables synchronous detection of over 40 cellular parameters,its full potential in disease classification is challenged by the limited types of recognition probes currently available.In this work,we synthesize a panel of heavy isotopeconjugated aptamers to profile cancer-associated signatures on the surface of hematological malignancy(HM)cells.Based on 15 molecular signatures,we performed cell-surface profiling that allowed the precise classification of 8 HM cell lines.Combined with machine-learning technology,this aptamer-based MC platform also achieved multiclass identification of HM subtypes in clinical sampleswith 100%accuracy in the training cohort and 80%accuracy in the test cohort.Therefore,we report an effective and practical strategy for precise cancer classification at the singlecell level,paving the way for its clinical use in the near future.

PRPS2 mutations drive acute lymphoblastic leukemia relapse through influencing PRPS1/2 hexamer stability

Tumor relapse is the major cause of treatment failure in childhood acute lymphoblastic leukemia(ALL),yet the underlying mechanisms are still elusive.Here,we demonstrate that phosphoribosyl pyrophosphate synthetase 2(PRPS2)mutations drive ALL relapse through influencing PRPS1/2 hexamer stability.Ultra-deep sequencing was performed to identify PRPS2 mutations in ALL samples.The effects of PRPS2 mutations on cell survival,cell apoptosis,and drug resistance were evaluated.In vitro PRPS2 enzyme activity and ADP/GDP feedback inhibition of PRPS enzyme activity were assessed.Purine metabolites were analyzed by ultra-performance liquid-chromatography tandem mass spectrometry(UPLC–MS/MS).Integrating sequencing data with clinical information,we identified PRPS2 mutations only in relapsed childhood ALL with thiopurine therapy.Functional PRPS2 mutations mediated purine metabolism specifically on thiopurine treatment by influencing PRPS1/2 hexamer stability,leading to reduced nucleotide feedback inhibition of PRPS activity and enhanced thiopurine resistance.The 3-amino acid V103-G104-E105,the key difference between PRPS1 and PRPS2,insertion in PRPS2 caused severe steric clash to the interface of PRPS hexamer,leading to its low enzyme activity.In addition,we demonstrated that PRPS2 P173R increased thiopurine resistance in xenograft models.Our work describes a novel mechanism by which PRPS2 mutants drive childhood ALL relapse and highlights PRPS2 mutations as biomarkers for relapsed childhood ALL.