Analyses of resected human brain metastases of breast cancer reveal the association between up-regulation of hexokinase 2 and poor prognosis.
Brain metastases of breast cancer seem to be increasingin incidence as systemic therapy improves. Metastatic disease in the brain is associated with high morbidity and mortality. We present the first gene expression analysis of laser-captured epithelial cells from resected human brain metastases of breast cancer compared with unlinked primary breast tumors. The tumors were matched for histology, tumor-node-metastasis stage, and hormone receptor status. Most differentially expressed genes were down-regulated in the brain metastases, which included, surprisingly, many genes associated with metastasis. Quantitative real-time PCR analysis confirmed statistically significant differences or strong trends in the expression of six genes: BMP1, PEDF, LAMgamma3, SIAH, STHMN3, and TSPD2. Hexokinase 2 (HK2) was also of interest because of its increased expression in brain metastases. HK2 is important in glucose metabolism and apoptosis. In agreement with our microarray results, HK2 levels (both mRNA and protein) were elevated in a brain metastatic derivative (231-BR) of the human breast carcinoma cell line MDA-MB-231 relative to the parental cell line (231-P) in vitro. Knockdown of HK2 expression in 231-BR cells using short hairpin RNA reduced cell proliferation when cultures were maintained in glucose-limiting conditions. Finally, HK2 expression was analyzed in a cohort of 123 resected brain metastases of breast cancer. High HK2 expression was significantly associated with poor patient survival after craniotomy (P = 0.028). The data suggest that HK2 overexpression is associated with metastasis to the brain in breast cancer and it may be a therapeutic target.
Palmieri
Diane
D
Women's Cancers Section, Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892-7322, USA.
Fitzgerald
Daniel
D
Shreeve
S Martin
SM
Hua
Emily
E
Bronder
Julie L
JL
Weil
Robert J
RJ
Davis
Sean
S
Stark
Andreas M
AM
Merino
Maria J
MJ
Kurek
Raffael
R
Mehdorn
H Maximilian
HM
Davis
Gary
G
Steinberg
Seth M
SM
Meltzer
Paul S
PS
Aldape
Kenneth
K
Steeg
Patricia S
PS
D000255:Adenosine Triphosphate / Q000378:metabolism; D001932:Brain Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000556:secondary* / Q000601:surgery; D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000502:physiology; D005260:Female; D055785:Gene Knockdown Techniques; D005947:Glucose / Q000378:metabolism; D006593:Hexokinase / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011379:Prognosis; D016016:Proportional Hazards Models; D015203:Reproducibility of Results; D015854:Up-Regulation
D000255:Adenosine Triphosphate; D006593:Hexokinase; D005947:Glucose