Functional genomic screening reveals asparagine dependence as a metabolic vulnerability in sarcoma.

Michaela Schneider,Simone Hettmer,Daria Tchessalova,William C Hahn,Anna C Schinzel,Roderick T Bronson,Nigel Gj Richards,Amy J Wagers,Christina L Parker

doi:10.7554/elife.09436

Abstract

Current therapies for sarcomas are often inadequate. This study sought to identify actionable gene targets by selective targeting of the molecular networks that support sarcoma cell proliferation. Silencing of asparagine synthetase (ASNS), an amidotransferase that converts aspartate into asparagine, produced the strongest inhibitory effect on sarcoma growth in a functional genomic screen of mouse sarcomas generated by oncogenic Kras and disruption of Cdkn2a. ASNS silencing in mouse and human sarcoma cell lines reduced the percentage of S phase cells and impeded new polypeptide synthesis. These effects of ASNS silencing were reversed by exogenous supplementation with asparagine. Also, asparagine depletion via the ASNS inhibitor amino sulfoximine 5 (AS5) or asparaginase inhibited mouse and human sarcoma growth in vitro, and genetic silencing of ASNS in mouse sarcoma cells combined with depletion of plasma asparagine inhibited tumor growth in vivo. Asparagine reliance of sarcoma cells may represent a metabolic vulnerability with potential anti-sarcoma therapeutic value.

Highlights

Soft-tissue sarcomas (STS) are a heterogeneous group of non-hematopoietic, mesodermal cancers
The myogenic differentiation status of the Ras-driven sarcomas generated in this system depends largely on the cell type transduced, known as the “cell-of-origin”: Kras; p16p19null satellite cells typically gave rise to RMS, whereas the identical oncogenetic lesions introduced into fibroadipogenic precursors within the MFA cell pool almost always produced sarcomas lacking myogenic differentiation features (Hettmer et al, 2011) (Figure 1—figure supplement 1)
As shRNA mediated silencing of Kras (G12v)-IRES-GFP, the driver oncogene used to initiate the mouse sarcomas, markedly inhibits the growth of Kras;p16p19null sarcoma cells (Figure 2A–B, Figure 2— figure supplement 1A–B), shRNAs directed against either GFP or KRAS served as positive controls in this screen and showed clear growth-inhibitory effects (Figure 1C–D, 1H-I)

Summary

Introduction

Soft-tissue sarcomas (STS) are a heterogeneous group of non-hematopoietic, mesodermal cancers. Certain STS types present with tissue-specific features, such as skeletal muscle differentiation in rhabdomyosarcoma (RMS) (Parham and Barr, 2013). For most STS tumors, cure depends on radical resection and/or radiation of the tumor, and therapeutic options for tumors that have spread regionally and/or systemically are limited (Linch et al, 2014). The genetic spectrum of STS is heterogeneous. Many tumors carry complex karyotypes with variable genetic changes; others express specific

Methods

Results

Conclusion