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Published on: June 27, 2020
EWS-FLI1-regulated Serine Synthesis and Exogenous Serine are Necessary for Ewing Sarcoma Cellular Proliferation and
Sameer H Issaq1, Arnulfo Mendoza2, Ria Kidner2
1Pediatric Oncology Branch, NCI, NIH, Bethesda, Maryland. issaqsh@mail.nih.gov.
Abstract:
Despite a growing body of knowledge about the genomic landscape of Ewing sarcoma, translation of basic discoveries into targeted therapies and significant clinical gains has remained elusive. Recent insights have revealed that the oncogenic transcription factor EWS-FLI1 can impact Ewing sarcoma cellular metabolism, regulating expression of 3-phosphoglycerate dehydrogenase (PHGDH), the first enzyme in de novo serine synthesis. Here, we have examined the importance of serine metabolism in Ewing sarcoma tumorigenesis and evaluated the therapeutic potential of targeting serine metabolism in preclinical models of Ewing sarcoma. We show that PHGDH knockdown resulted in decreased Ewing sarcoma cell proliferation, especially under serine limitation, and significantly inhibited xenograft tumorigenesis in preclinical orthotopic models of Ewing sarcoma. In addition, the PHGDH inhibitor NCT-503 caused a dose-dependent decrease in cellular proliferation. Moreover, we report a novel drug combination in which nicotinamide phosphoribosyltransferase (NAMPT) inhibition, which blocks production of the PHGDH substrate NAD+, synergized with NCT-503 to abolish Ewing sarcoma cell proliferation and tumor growth. Furthermore, we show that serine deprivation inhibited Ewing sarcoma cell proliferation and tumorigenesis, indicating that Ewing sarcoma cells depend on exogenous serine in addition to de novo serine synthesis. Our findings suggest that serine metabolism is critical for Ewing sarcoma tumorigenesis, and that targeting metabolic dependencies should be further investigated as a potential therapeutic strategy for Ewing sarcoma. In addition, the combination strategy presented herein may have broader clinical applications in other PHGDH-overexpressing cancers as well.
Insights
Targeting serine metabolism, crucial for Ewing sarcoma growth, shows therapeutic promise. Inhibiting PHGDH or combining NAMPT and PHGDH inhibitors significantly reduced tumor development in preclinical models.
Area of Science:
- Oncology
- Cancer Metabolism
- Molecular Biology
Background:
- Ewing sarcoma's genomic landscape is increasingly understood, yet targeted therapies remain limited.
- The oncogenic transcription factor EWS-FLI1 influences Ewing sarcoma cell metabolism by regulating 3-phosphoglycerate dehydrogenase (PHGDH).
- PHGDH is the rate-limiting enzyme in de novo serine synthesis, a pathway implicated in cancer cell growth.
Purpose of the Study:
- To investigate the role of serine metabolism in Ewing sarcoma tumorigenesis.
- To evaluate the therapeutic potential of targeting serine metabolism in preclinical Ewing sarcoma models.
- To explore novel drug combinations for Ewing sarcoma treatment.
Main Methods:
- PHGDH knockdown and its effect on Ewing sarcoma cell proliferation and xenograft tumor growth.
- Treatment with the PHGDH inhibitor NCT-503.
- Combination therapy involving nicotinamide phosphoribosyltransferase (NAMPT) inhibition and NCT-503.
- Assessment of Ewing sarcoma cell proliferation and tumorigenesis under serine deprivation.
Main Results:
- PHGDH knockdown decreased Ewing sarcoma cell proliferation and inhibited xenograft tumor growth.
- NCT-503 treatment resulted in a dose-dependent decrease in cellular proliferation.
- Combined NAMPT and NCT-503 inhibition synergistically abolished Ewing sarcoma cell proliferation and tumor growth.
- Serine deprivation inhibited Ewing sarcoma cell proliferation and tumorigenesis, highlighting dependence on both de novo synthesis and exogenous serine.
Conclusions:
- Serine metabolism is critical for Ewing sarcoma tumorigenesis.
- Targeting metabolic dependencies, specifically serine metabolism, represents a promising therapeutic strategy for Ewing sarcoma.
- A combination strategy targeting NAMPT and PHGDH may offer broader clinical applications in other PHGDH-overexpressing cancers.
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