Immunoexpression of tumor suppressor genes p53, p21 WAF1/CIP1 and p27 KIP1 in humam astrocystic tumors.
The aim of the present study was to evaluate the tumor suppressor genes p53, p21 WAF1/CIP1 and p27 KIP1 expression in astrocytic tumors, correlating the findings with the histopathological grade (WHO). An immunohistochemical study of the p53, p21 and p27 proteins using the streptavidin-biotin-peroxidase method was performed in fifty-five astrocytomas (13 grade I, 14 grade II, 7 grade III and 21 grade IV) and five samples of non-tumor brain tissue (negative control). p53 positive indices (PI) and labeling indices (LI) showed tendency to increase according to malignant progression. The nuclear expression of p27 presented similar inclination, except for the PI reduction verified in grade IV tumors. Otherwise, the cytoplasmic p27 staining was more evident between high-grade tumors (III and IV). p53 and nuclear p27 expression was correlated with the histological classification (p<0.01; test H). On the other hand, p21 indices revealed a propensity to reduction in agreement with malignant evolution of the astrocytic tumors, except for high scores observed in grade IV tumors. The non-tumor samples did not show any expression of these proteins. These results indicated the p53 mutation as an initial, relevant and potentially predictor of tumor progression event in astrocytomas, with the detection of p21 protein as an important resource for the deduction of functional situation of this gene. Moreover, the activation of p27 KIP1 was preserved in the astrocytic tumors and its cytoplasmic manifestation seems to be resultant of its nuclear expression, not demonstrating a direct impact in astrocytomas tumorigenesis.
Faria
Mário Henrique Girão
MH
Department of Physiology and Pharmacology, Molecular Genetics Laboratory, School of Medicine, Federal University of Ceará, Fortaleza CE, Brazil. mariofaria@doctor.com
Patrocínio
Régia Maria do Socorro Vidal do
RM
Moraes Filho
Manoel Odorico de
MO
Rabenhorst
Silvia Helena Barem
SH
D001254:Astrocytoma / Q000235:genetics* / Q000473:pathology; D014408:Biomarkers, Tumor / Q000032:analysis / Q000235:genetics; D016022:Case-Control Studies; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000032:analysis* / Q000235:genetics; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000032:analysis* / Q000235:genetics; D018450:Disease Progression; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53; D005909:Glioblastoma / Q000235:genetics* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D009154:Mutation / Q000235:genetics; D009367:Neoplasm Staging; D016159:Tumor Suppressor Protein p53 / Q000032:analysis* / Q000235:genetics
D014408:Biomarkers, Tumor; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016159:Tumor Suppressor Protein p53; D050760:Cyclin-Dependent Kinase Inhibitor p27