Glycogen synthase kinase 3b biology in bone and soft tissue sarcomas

Bone and soft tissue sarcomas are malignant neoplasms probably originating from musculoskeletal and mesenchymal progenitor cells.More than 80 different histopathological subtypes are encountered in orthopedics.The standard of care for sarcoma patients involves a multidisciplinary combination of surgery,anthracycline-based multiagent chemotherapy and radiation.Unfortunately,these are associated with adverse events and occasionally disappointing outcomes.Various genomic-,biologically-,and immunologically-based therapies are still under evaluation in early-phase clinical trials.However,there are strong barriers to the development and clinical translation of new therapeutic modalities.This is due to the rarity of these diseases,the broad spectrum of tumor subtypes with genetic and biological heterogeneity,and the wide variability in clinical manifestation,response to treatment and prognosis.A potential approach toward overcoming this barrier is to identify therapeutic targets that cover multiple sarcoma types.Glycogen synthase kinase 3b(GSK3b)has emerged as a common therapeutic target in more than 25 different cancer types.Here we review the evidence for tumor-promoting roles of GSK3b in the major types of bone and soft tissue sarcomas including osteosarcoma,rhabdomyosarcoma,synovial sarcoma,and fibrosarcoma.In this review,we describe the therapeutic effects of inhibiting GSK3b in these sarcoma types,while also protecting healthy cells and tissues from detrimental effects associated with conventional therapies,such as doxorubicin-induced cardiotoxicity.Consequently,we highlight GSK3b as a potential therapeutic target spanning multiple sarcoma types.

Epidermal growth factor receptor stabilizes programmed death ligand 1 by glycosylation in colorectal cancer with microstatellite instability status

Programmed death ligand-1(PD-L1)is involved in inhibiting of T lymphocyte proliferation,producing cytokine,cytolytic activity,and suppressing of the immune response.Genes with molecular alterations involved in DNA mismatch repair promote cancer initiation and tumor progression.Clinical studies show that colorectal cancer(CRC)patients harboring microsatellite instability(MSI)have a higher anti-programmed cell death protein 1/PD-L1 immunotherapy response ratio compared with microsatellite stable subgroup patients.The underlying mechanism has however remained unclear.Here,we found that compared with microsatellite stable samples,PD-L1 was glycosylated and highly expressed both in MSI CRC cell lines and tissue samples.Specifically,PD-L1 was Nglycosylated at its N35,N192,N200,and N219 sites,and the four glycosylation sites were all responsible for PD-L1 degradation.Additionally,non-glycosylated PD-L1 underwent rapid degradation compared with glycosylated PD-L1 through the 26S proteasome pathway.The faster degradation of the non-glycosylated PD-L1 was ascribed to its binding to glycogen synthase kinase 3b via ubiquitination.This degradation phenotype was,however,not observed for glycosylated PD-L1.Significantly,glycosylated PD-L1 was up-regulated by activated epidermal growth factor receptor in MSI CRC cells.Together,our results indicate that epidermal growth factor receptor stabilized PD-L1 via glycosylation in MSI CRC cells,uncovering a novel role of PD-L1 in MSI CRC immunosuppression and disease progression.The study was approved by the Clinical Ethics Review Committee at the Six Affiliated Hospital of Sun Yat-sen University,China(Approval No.2019ZSLYEC-005).