Nanoparticle enhanced combination therapy for stem-like progenitors defined by single-cell transcriptomics in chemotherapy-resistant osteosarcoma

The adaptation of osteosarcoma cells to therapeutic pressure impedes the efficacy of chemotherapy for osteosarcoma.However,the characteristics and cellular organization of therapy-resistant cells in osteosarcoma tumors remain elusive.Here,we utilized single-cell transcriptomics to systematically map the cell-type-specific gene expression in a chemotherapy-resistant osteosarcoma tumor.Our data demonstrated the VEGFR2-JMJD3-abundant subsets as quiescent stem-like cells,thereby establishing the hierarchy of therapy-resistant actively cycling progenitor pools(JMJD3-abundant)in osteosarcoma.VEGFR2 inhibitor and JMJD3 inhibitor synergistically impeded osteosarcoma cell propagation and tumor growth.Although osteosarcoma cells are predisposed to apoptosis induced by the synergistic therapy through activation of the CHOP pro-apoptotic factor via the endoplasmic reticulum(ER)stress,the stem-like/progenitor cells exhibit an adaptive response,leading to their survival.Reduction in cellular glutathione levels in stem-like/progenitor cells caused by the treatment with a glutathione synthesis inhibitor increases ER stress-induced apoptosis.Importantly,the marked therapeutic improvement of synergistic therapy against stem-like/progenitor cells was achieved by using glutathione-scavenging nanoparticles,which can load and release the drug pair effectively.Overall,our study provides a framework for understanding glutathione signaling as one of the therapeutic vulnerabilities of stem-like/progenitor cells.Broadly,these findings revealed a promising arsenal by encapsulating glutathione-scavenging nanoparticles with co-targeting VEGFR2 and JMJD3 to eradicate chemotherapy-resistant osteosarcoma.