Eukaryotic initiation factors (eIF) 2alpha and 4E expression, localization, and phosphorylation in brain tumors.
Increased protein synthesis is regulated, in part, by two eukaryotic translation initiation factors (eIFs): eIF4E and eIF2alpha. One or both of these factors are often overexpressed in several types of cancer cells; however, no data are available at present regarding eIF4E and eIF2alpha levels in brain tumors. In this study, we analyzed the expression, subcellular localization and phosphorylation states of eIF4E and eIF2alpha in 64 brain tumors (26 meningiomas, 16 oligodendroglial tumors, and 22 astrocytomas) and investigated the correlation with the expression of MIB-1, p53, and cyclin D1 proteins as well. There are significant differences in the phosphorylated eIF4E levels between the tumors studied, being the highest in meningiomas and the lowest in the oligodendroglial tumors. Relative to subcellular localization, eIF4E is frequently found in the nucleus of the oligodendroglial tumors and rarely in the same compartment of the meningiomas, whereas eIF2alpha showed an inverse pattern. Finally, cyclin D1 levels directly correlate with the phosphorylation status of both factors. The different expression, phosphorylation, or/and subcellular distribution of eIF2alpha and eIF4E within the brain types of tumors studied could indicate that different pathways are activated for promoting cell cycle proliferation, for instance, leading to increased cyclin D1 expression.
Tejada
Sonia
S
Servicio de Neurocirugía, Hospital Ramón y Cajal, Ctra. Colmenar Km. 9, 28034 Madrid, Spain.
Lobo
M Val T
MV
García-Villanueva
Mercedes
M
Sacristán
Silvia
S
Pérez-Morgado
M Isabel
MI
Salinas
Matilde
M
Martín
M Elena
ME
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D049109:Cell Proliferation; D019938:Cyclin D1 / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism*; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010766:Phosphorylation; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D055815:Young Adult
D014408:Biomarkers, Tumor; D015852:Eukaryotic Initiation Factor-2; D039561:Eukaryotic Initiation Factor-4E; D019394:Ki-67 Antigen; D016159:Tumor Suppressor Protein p53; D019938:Cyclin D1