Review Article

The Molecular Biology of Brain Metastasis

Table 1

Genes associated with increased metastatic potential.

GenesCancer site (primary)Role and implicationsOMIM no.Chromosome location

RHoCMelanomaRegulates remodeling of actin cytoskeleton during morphogenesis and motility. Important in tumor cell invasion1653801p21-p13

LOXBreast
Head and neck cancer
Increases invasiveness of hypoxic human cancer cells through cell matrix adhesion and focal adhesion kinase activity1534555q23.1-q23.2

VEGFLung
Breast
Melanoma
Colon
Angiogenic growth factor
Inhibition decreases brain metastasis formation; reduces blood vessel formation and cell proliferation; increases apoptosis
1922406p21.1

CSF1Breast
Lung
Stimulate macrophage proliferation and subsequent release of growth factors1204201p13.3

ID1Breast
Lung
Involved in matrix remodeling, intracellular signaling, and angiogenesis60034920q11.21

TWIST1Breast
Gastric
Rhabdomyosarcoma
Melanoma
Hepatocellular
Causes loss of E-cadherin-mediated cell-cell adhesion, activates mesenchymal markers, and induces cell motility by promoting epithelial-mesenchymal transition6016227p21.1

METRenal cell cancerAffects a wide range of biological activity depending on the cell target, varying from mitogenesis, morphogenesis, and motogenesis1648607q31.2

MMP-9Colorectal
Breast
Melanoma
Chondrosarcoma
Extracellular matrix degradation, tissue remodeling12036120q13.12

NEDD9MelanomaAcquisition of a metastatic potential6022656p24.2

LEF1LungTranscriptional effecter—WNT pathway; predilection for brain metastasis
Knockdown inhibits brain metastasis, decreases colony formation; in vitro decreases invasion
1532544q25

HOXB9Lung
Breast
Homeobox gene family; critical for embryonic segmentation and patterning. Also a TCF4 target
Knockdown in vitro decreased invasion and colony formation; in vivo appears to inhibit brain metastasis
14296417q21.32

BMP4Lung
Colorectal
Plays an essential role in embryonic development and may be an essential component of the epithelial-mesenchymal transition11226214q22.2

STAT3MelanomaCell signaling transcription factor
Reduction suppresses brain metastasis; decreases angiogenesis in vivo and cellular invasion in vitro
10258217q21.2