title: An siRNA screen identifies RSK1 as a key modulator of lung cancer metastasis.
abstract: We performed a kinome-wide siRNA screen and identified 70 kinases altering cell migration in A549 lung cancer cells. In particular, ribosomal S6 kinase 1 (RSK1) silencing increased, whereas RSK2 and RSK4 downregulation inhibited cell motility. In a secondary collagen-based three-dimensional invasion screen, 38 of our hits cross-validated, including RSK1 and RSK4. In two further lung cancer cell lines, RSK1 but not RSK4 silencing showed identical modulation of cell motility. We therefore selected RSK1 for further investigation. Bioinformatic analysis followed by co-immunoprecipitation-based validation revealed that the actin regulators VASP and Mena interact with RSK1. Moreover, RSK1 phosphorylated VASP on T278, a site regulating its binding to actin. In addition, silencing of RSK1 enhanced the metastatic potential of these cells in vivo using a zebrafish model. Finally, we investigated the relevance of this finding in human lung cancer samples. In isogenically matched tissue, RSK1 was reduced in metastatic versus primary lung cancer lesions. Moreover, patients with RSK1-negative lung tumours showed increased number of metastases. Our results suggest that the findings of our high-throughput in vitro screen can reliably identify relevant clinical targets and as a proof of principle, RSK1 may provide a biomarker for metastasis in lung cancer patients.
authors.affiliation: Department of Oncology, Hammersmith Campus, Cyclotron Building, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Lara
authors.forename: F A
authors.initials: FA
authors.lastname: Mauri
authors.forename: H
authors.initials: H
authors.lastname: Taylor
authors.forename: R
authors.initials: R
authors.lastname: Derua
authors.forename: A
authors.initials: A
authors.lastname: Shia
authors.forename: C
authors.initials: C
authors.lastname: Gray
authors.forename: A
authors.initials: A
authors.lastname: Nicols
authors.forename: R J
authors.initials: RJ
authors.lastname: Shiner
authors.forename: E
authors.initials: E
authors.lastname: Schofield
authors.forename: P A
authors.initials: PA
authors.lastname: Bates
authors.forename: E
authors.initials: E
authors.lastname: Waelkens
authors.forename: M
authors.initials: M
authors.lastname: Dallman
authors.forename: J
authors.initials: J
authors.lastname: Lamb
authors.forename: D
authors.initials: D
authors.lastname: Zicha
authors.forename: J
authors.initials: J
authors.lastname: Downward
authors.forename: M J
authors.initials: MJ
authors.lastname: Seckl
authors.forename: O E
authors.initials: OE
authors.lastname: Pardo
mesh_terms: D000818:Animals; D001665:Binding Sites; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000235:genetics* / Q000378:metabolism; D013912:Threonine / Q000235:genetics / Q000378:metabolism; D014183:Transplantation, Heterologous; D015027:Zebrafish / Q000196:embryology; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D015815:Cell Adhesion Molecules; C511939:Enah protein, human; D008840:Microfilament Proteins; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D000098662:Vasodilator-Stimulated Phosphoprotein; D049452:Green Fluorescent Proteins; D013912:Threonine; C069329:RPS6KA1 protein, human; D038744:Ribosomal Protein S6 Kinases, 90-kDa