Overexpression of cyclin A and cyclin B1 proteins in astrocytomas.
BACKGROUND
Cyclins are proteins that are expressed during the progression of a normal cell through the cell cycle. In a number of cancers, overexpression of cyclin A and cyclin B1 proteins has been reported, and in some instances the levels of expression correlated well with the grades of malignancy. The expression of cyclin A and cyclin B1 proteins in astrocytoma may be linked to the histologic grade or proliferative activities.


OBJECTIVE
To study the expression of cyclin A and cyclin B1 proteins in astrocytomas and correlate the labeling indices (LIs) of cyclin A and cyclin B1 with histologic grade and Ki-67 LI.


METHODS
The surgical biopsy specimens from 65 adults with astrocytomas were reviewed and divided into grades based on the World Health Organization system. The paraffin sections were immunostained using primary antibodies against Ki-67, cyclin A, and cyclin B1. The LIs of these astrocytomas for the 3 different antibodies were determined by computerized image analysis.


RESULTS
The cyclin A LI showed good correlation with astrocytoma grade and Ki-67 LI. Both the nuclear and cytoplasmic cyclin B LIs correlated well with the tumor grade but showed poor correlation with Ki-67 LI.


CONCLUSIONS
This study suggests that although both cyclin A and B protein expression are related to the grade of malignancy in astrocytomas, cyclin A levels more generally reflect the proliferative state of these tumors. We also provide indirect evidence that cyclin B1 is associated with the aberrant progression through the G2-M phase checkpoint in astrocytomas.
Allan
K
K
Department of Pathology, Sunnybrook and Women's College Health Science Center, University of Toronto, Toronto, Ontario.
Jordan
R C
RC
Ang
L C
LC
Taylor
M
M
Young
B
B
D001254:Astrocytoma / Q000378:metabolism* / Q000473:pathology; D014408:Biomarkers, Tumor / Q000378:metabolism; D002452:Cell Count; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D019925:Cyclin A / Q000378:metabolism*; D019926:Cyclin B / Q000378:metabolism*; D056744:Cyclin B1; D003593:Cytoplasm / Q000378:metabolism / Q000473:pathology; D005909:Glioblastoma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D019394:Ki-67 Antigen / Q000378:metabolism; D009367:Neoplasm Staging; D015173:Supratentorial Neoplasms / Q000378:metabolism* / Q000473:pathology
D014408:Biomarkers, Tumor; C534699:CCNB1 protein, human; D019925:Cyclin A; D019926:Cyclin B; D056744:Cyclin B1; D019394:Ki-67 Antigen