title: Functional genomics reveal that the serine synthesis pathway is essential in breast cancer.
abstract: Cancer cells adapt their metabolic processes to drive macromolecular biosynthesis for rapid cell growth and proliferation. RNA interference (RNAi)-based loss-of-function screening has proven powerful for the identification of new and interesting cancer targets, and recent studies have used this technology in vivo to identify novel tumour suppressor genes. Here we developed a method for identifying novel cancer targets via negative-selection RNAi screening using a human breast cancer xenograft model at an orthotopic site in the mouse. Using this method, we screened a set of metabolic genes associated with aggressive breast cancer and stemness to identify those required for in vivo tumorigenesis. Among the genes identified, phosphoglycerate dehydrogenase (PHGDH) is in a genomic region of recurrent copy number gain in breast cancer and PHGDH protein levels are elevated in 70% of oestrogen receptor (ER)-negative breast cancers. PHGDH catalyses the first step in the serine biosynthesis pathway, and breast cancer cells with high PHGDH expression have increased serine synthesis flux. Suppression of PHGDH in cell lines with elevated PHGDH expression, but not in those without, causes a strong decrease in cell proliferation and a reduction in serine synthesis. We find that PHGDH suppression does not affect intracellular serine levels, but causes a drop in the levels of α-ketoglutarate, another output of the pathway and a tricarboxylic acid (TCA) cycle intermediate. In cells with high PHGDH expression, the serine synthesis pathway contributes approximately 50% of the total anaplerotic flux of glutamine into the TCA cycle. These results reveal that certain breast cancers are dependent upon increased serine pathway flux caused by PHGDH overexpression and demonstrate the utility of in vivo negative-selection RNAi screens for finding potential anticancer targets.
authors.affiliation: Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, Massachusetts 02142, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Possemato
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Marks
authors.forename: Yoav D
authors.initials: YD
authors.lastname: Shaul
authors.forename: Michael E
authors.initials: ME
authors.lastname: Pacold
authors.forename: Dohoon
authors.initials: D
authors.lastname: Kim
authors.forename: Kıvanç
authors.initials: K
authors.lastname: Birsoy
authors.forename: Shalini
authors.initials: S
authors.lastname: Sethumadhavan
authors.forename: Hin-Koon
authors.initials: HK
authors.lastname: Woo
authors.forename: Hyun G
authors.initials: HG
authors.lastname: Jang
authors.forename: Abhishek K
authors.initials: AK
authors.lastname: Jha
authors.forename: Walter W
authors.initials: WW
authors.lastname: Chen
authors.forename: Francesca G
authors.initials: FG
authors.lastname: Barrett
authors.forename: Nicolas
authors.initials: N
authors.lastname: Stransky
authors.forename: Zhi-Yang
authors.initials: ZY
authors.lastname: Tsun
authors.forename: Glenn S
authors.initials: GS
authors.lastname: Cowley
authors.forename: Jordi
authors.initials: J
authors.lastname: Barretina
authors.forename: Nada Y
authors.initials: NY
authors.lastname: Kalaany
authors.forename: Peggy P
authors.initials: PP
authors.lastname: Hsu
authors.forename: Kathleen
authors.initials: K
authors.lastname: Ottina
authors.forename: Albert M
authors.initials: AM
authors.lastname: Chan
authors.forename: Bingbing
authors.initials: B
authors.lastname: Yuan
authors.forename: Levi A
authors.initials: LA
authors.lastname: Garraway
authors.forename: David E
authors.initials: DE
authors.lastname: Root
authors.forename: Mari
authors.initials: M
authors.lastname: Mino-Kenudson
authors.forename: Elena F
authors.initials: EF
authors.lastname: Brachtel
authors.forename: Edward M
authors.initials: EM
authors.lastname: Driggers
authors.forename: David M
authors.initials: DM
authors.lastname: Sabatini
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002952:Citric Acid Cycle / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D023281:Genomics; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D007656:Ketoglutaric Acids / Q000378:metabolism; D008545:Melanoma / Q000201:enzymology / Q000235:genetics; D051379:Mice; D009368:Neoplasm Transplantation; D050543:Phosphoglycerate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012694:Serine / Q000096:biosynthesis*
chemical_list: D014408:Biomarkers, Tumor; D007656:Ketoglutaric Acids; D018698:Glutamic Acid; D012694:Serine; D050543:Phosphoglycerate Dehydrogenase