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Acta Neuropathol. 2017 Dec;134(6):923-940. doi: 10.1007/s00401-017-1757-z. Epub 2017 Aug 1.

RNAi screen identifies essential regulators of human brain metastasis-initiating cells.

Author information

1
MDCL 5027, Stem Cell and Cancer Research Institute, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.
2
Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada.
3
Department of Surgery, McMaster University, Hamilton, ON, Canada.
4
Departments of Medical Biophysics and Computer Science, University of Toronto, Toronto, ON, Canada.
5
Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
6
Donnelly Centre, Toronto, ON, Canada.
7
The Hospital for Sick Children, Toronto, ON, Canada.
8
Anatomic Pathology, St. Joseph's Healthcare, Hamilton, ON, Canada.
9
Princess Margaret Cancer Centre, IBM Life Sciences Discovery Centre, University Health Network, Toronto, ON, Canada.
10
MDCL 5027, Stem Cell and Cancer Research Institute, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada. ssingh@mcmaster.ca.
11
Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada. ssingh@mcmaster.ca.
12
Department of Surgery, McMaster University, Hamilton, ON, Canada. ssingh@mcmaster.ca.

Abstract

Brain metastases (BM) are the most common brain tumor in adults and are a leading cause of cancer mortality. Metastatic lesions contain subclones derived from their primary lesion, yet their functional characterization is limited by a paucity of preclinical models accurately recapitulating the metastatic cascade, emphasizing the need for a novel approach to BM and their treatment. We identified a unique subset of stem-like cells from primary human patient brain metastases, termed brain metastasis-initiating cells (BMICs). We now establish a BMIC patient-derived xenotransplantation (PDXT) model as an investigative tool to comprehensively interrogate human BM. Using both in vitro and in vivo RNA interference screens of these BMIC models, we identified SPOCK1 and TWIST2 as essential BMIC regulators. SPOCK1 in particular is a novel regulator of BMIC self-renewal, modulating tumor initiation and metastasis from the lung to the brain. A prospective cohort of primary lung cancer specimens showed that SPOCK1 was overexpressed only in patients who ultimately developed BM. Protein-protein interaction network mapping between SPOCK1 and TWIST2 identified novel pathway interactors with significant prognostic value in lung cancer patients. Of these genes, INHBA, a TGF-β ligand found mutated in lung adenocarcinoma, showed reduced expression in BMICs with knockdown of SPOCK1. In conclusion, we have developed a useful preclinical model of BM, which has served to identify novel putative BMIC regulators, presenting potential therapeutic targets that block the metastatic process, and transform a uniformly fatal systemic disease into a locally controlled and eminently more treatable one.

KEYWORDS:

BMIC; BMIC regulators; Brain metastasis; Brain metastasis-initiating cell; Non-small cell lung cancer; Patient-derived xenotransplant; SPOCK1; TWIST2

PMID:
28766011
DOI:
10.1007/s00401-017-1757-z
[Indexed for MEDLINE]

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