Secretory defects in pediatric osteosarcoma result from downregulation of selective COPII coatomer proteins

• Published in: iScience Vol. 25; no. 4; p. 104100
• Main Authors: Wood, Rachael K., Flory, Ashley R., Mann, Melissa J., Talbot, Lindsay J., Hendershot, Linda M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.04.2022; Elsevier
• Subjects: Cancer; Cell biology; Cell biology; Cancer
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2022.104100

Pediatric osteosarcomas (OS) exhibit extensive genomic instability that has complicated the identification of new targeted therapies. We found the vast majority of 108 patient tumor samples and patient-derived xenografts (PDXs), which display an unusually dilated endoplasmic reticulum (ER), have reduced expression of four COPII vesicle components that trigger aberrant accumulation of procollagen-I protein within the ER. CRISPR activation technology was used to increase the expression of two of these, SAR1A and SEC24D, to physiological levels. This was sufficient to resolve the dilated ER morphology, restore collagen-I secretion, and enhance secretion of some extracellular matrix (ECM) proteins. However, orthotopic xenograft growth was not adversely affected by restoration of only SAR1A and SEC24D. Our studies reveal the mechanism responsible for the dilated ER that is a hallmark characteristic of OS and identify a highly conserved molecular signature for this genetically unstable tumor. Possible relationships of this phenotype to tumorigenesis are discussed. [Display omitted] •Exceptionally dilated ER is a conserved feature of genetically variable osteosarcomas.•Data from 108 pediatric OS reveal a widespread downregulation of 4 COPII components.•COPII insufficiency reduced secretion of collagen and extracellular matrix proteins.•Reexpression of SAR1A and SEC24D was sufficient to restore ER morphology. Cell biology; Cancer