title: Human breast cancer metastases to the brain display GABAergic properties in the neural niche.
abstract: Dispersion of tumors throughout the body is a neoplastic process responsible for the vast majority of deaths from cancer. Despite disseminating to distant organs as malignant scouts, most tumor cells fail to remain viable after their arrival. The physiologic microenvironment of the brain must become a tumor-favorable microenvironment for successful metastatic colonization by circulating breast cancer cells. Bidirectional interplay of breast cancer cells and native brain cells in metastasis is poorly understood and rarely studied. We had the rare opportunity to investigate uncommonly available specimens of matched fresh breast-to-brain metastases tissue and derived cells from patients undergoing neurosurgical resection. We hypothesized that, to metastasize, breast cancers may escape their normative genetic constraints by accommodating and coinhabiting the neural niche. This acquisition or expression of brain-like properties by breast cancer cells could be a malignant adaptation required for brain colonization. Indeed, we found breast-to-brain metastatic tissue and cells displayed a GABAergic phenotype similar to that of neuronal cells. The GABAA receptor, GABA transporter, GABA transaminase, parvalbumin, and reelin were all highly expressed in breast cancer metastases to the brain. Proliferative advantage was conferred by the ability of breast-to-brain metastases to take up and catabolize GABA into succinate with the resultant formation of NADH as a biosynthetic source through the GABA shunt. The results suggest that breast cancers exhibit neural characteristics when occupying the brain microenvironment and co-opt GABA as an oncometabolite.
authors.affiliation: Divisions of Neurosurgery and Pathology, Departments of Molecular Medicine, Immunology, and Neurobiochemistry, and Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, CA 91010.
authors.forename: Josh
authors.initials: J
authors.lastname: Neman
authors.forename: John
authors.initials: J
authors.lastname: Termini
authors.forename: Sharon
authors.initials: S
authors.lastname: Wilczynski
authors.forename: Nagarajan
authors.initials: N
authors.lastname: Vaidehi
authors.forename: Cecilia
authors.initials: C
authors.lastname: Choy
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Kowolik
authors.forename: Hubert
authors.initials: H
authors.lastname: Li
authors.forename: Amanda C
authors.initials: AC
authors.lastname: Hambrecht
authors.forename: Eugene
authors.initials: E
authors.lastname: Roberts
authors.forename: Rahul
authors.initials: R
authors.lastname: Jandial
mesh_terms: D000612:4-Aminobutyrate Transaminase / Q000378:metabolism; D001932:Brain Neoplasms / Q000378:metabolism / Q000556:secondary*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005260:Female; D050485:GABA Plasma Membrane Transport Proteins / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006801:Humans; D007395:Interneurons / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D010641:Phenotype; D011963:Receptors, GABA-A / Q000378:metabolism; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000378:metabolism; D059016:Tumor Microenvironment; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D050485:GABA Plasma Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D010320:Parvalbumins; D011963:Receptors, GABA-A; D000091042:Reelin Protein; D005680:gamma-Aminobutyric Acid; D000612:4-Aminobutyrate Transaminase; C000717127:RELN protein, human; D012697:Serine Endopeptidases; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1
keywords: brain metastasis; tumor microenvironment