BACKGROUND: xCT is a light chain of the cystine/glutamate antiporter system xc−. Glutamate that is released by system xc− plays an important role in the infiltration of glioblastoma (GBM) cells. Furthermore, increased glutathione synthesis by system xc− may protect tumor cells against oxidative stress induced by radiotherapy and chemotherapy.
OBJECTIVE: To investigate whether the levels of xCT expression correlated with infiltrative imaging phenotypes on magnetic resonance imaging and outcomes in patients with GBMs.
METHODS: Forty patients with histologically confirmed primary GBMs were included in the study. Patient charts were retrospectively reviewed for age, sex, Karnofsky Performance Status Scale score, Mini-Mental State Examination score, magnetic resonance imaging features, xCT expression, isocitrate dehydrogenase 1 R132H expression, O6-methylguanine-DNA methyltransferase promoter methylation status, type of surgery, progression-free survival, and overall survival.
RESULTS: In invasive margins, xCT expression was weak in 20 patients and strong in 20 patients. A Cox regression model revealed that a Karnofsky Performance Status Scale score less than 60 (hazard ratio [HR]: 4.525; P = .01), partial removal (HR: 2.839; P = .03), and strong xCT expression (HR: 4.134; P < .001) were significantly associated with shorter progression-free survival and that partial removal (HR: 2.865; P = .03), weak isocitrate dehydrogenase 1 R132H expression (HR: 15.729; P = .01), and strong xCT expression (HR: 2.863; P = .04) were significantly associated with shorter overall survival.
CONCLUSION: These findings suggest that xCT is an independent predictive factor in GBMs.
ABBREVIATIONS: EAAT-2, excitatory amino acid transporter 2
IDH1, isocitrate dehydrogenase 1
KPS, Karnofsky Performance Status Scale
MGMT, O6-methylguanine–DNA methyltransferase
MMSE, Mini-Mental Status Examination
OS, overall survival
PFS, progression-free survival
Departments of *Neurosurgery
‡Integrative Physiology and Bio-Nano Medicine
§Pathology and Laboratory Medicine, National Defense Medical College, Tokorozawa, Saitama, Japan
Correspondence: Satoru Takeuchi, MD, Department of Neurosurgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. E-mail: firstname.lastname@example.org
Received March 22, 2012
Accepted September 14, 2012