Antiangiogenic and proapoptotic effects of dietary restriction on experimental mouse and human brain tumors.
OBJECTIVE
The antiangiogenic and proapoptotic mechanisms of dietary caloric restriction (DR) are unknown. In this study, we evaluated the effects of moderate (40%) DR on the orthotopic growth of mouse and human brain tumors that differ in cell origin, angiogenicity, host environment, and biochemical composition.


METHODS
A malignant mouse astrocytoma (CT-2A) and a human glioma (U87-MG) were highly angiogenic and fast growing, whereas a mouse ependymoblastoma was less vascularized and slower growing. The tumors were evaluated for growth, cell proliferation, microvessel density, and apoptosis under DR and ad libitum feeding. Serum vascular endothelial growth factor and insulin-like growth factor I levels were examined as angiogenic biomarkers.


RESULTS
DR significantly decreased vascularity (factor VIII) and increased apoptosis (terminal deoxynucleotidyl transferase-mediated nick end labeling) in all tumors. These effects were associated with enhanced caspase-3 and poly(ADP-ribose) polymerase cleavage in the CT-2A and ependymoblastoma tumors, but not in the U87-MG tumor. DR also caused reductions of serum insulin-like growth factor I and glucose levels.


CONCLUSIONS
DR had significant antiangiogenic and proapoptotic effects in the three distinct brain tumor models. DR, however, had differential effects on cell proliferation, biomarkers of angiogenesis, and apoptosis, suggesting multiple mechanisms of action. Because extensive angiogenesis and resistance to apoptosis are hallmarks of gliomas, this study provides new insight into the molecular basis of the DR-induced inhibition of brain tumor growth.
Biology Department, Boston College, Chestnut Hill, Massachusetts 02467, USA.
Purna
P
Mukherjee
Laura E
LE
Abate
Thomas N
TN
Seyfried
D000818:Animals; D017209:Apoptosis; D001254:Astrocytoma; D001932:Brain Neoplasms / Q000098:blood supply* / Q000473:pathology* / Q000517:prevention & control*; D045744:Cell Line, Tumor; D004038:Diet, Reducing; D004195:Disease Models, Animal; D005910:Glioma; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D009389:Neovascularization, Pathologic / Q000517:prevention & control