Relationship between expression of p21(WAF1/CIP1) radioresistance in humangliomas

The role of p21(WAF1/CIPI) (p21) in DNA repair and apoptosis following gamm a-irradiation remains controversial. In this study the influence of p21 on the radiosensitivity of human brain tumors was investigated. Resected tumor s were stained immunohistochemically for p21, Expression of p21 in astrocyt ic tumors was high, but it was low in medulloblastomas, germinomas, and pri mary malignant lymphomas. Glioma and medulloblastoma cell lines were transf ected with pcDNA/p21 to cause p21 overexpression, then tumor-cell colony fo rmation and apoptosis were assessed following gamma-irradiation of the tran sfected and nontransfected cells. Overexpression of p21 enhanced clonogenic survival and suppressed apoptosis after gamma-irradiation in human brain t urner cell lines with or without p53 protein deficiency Radioresistance was acquired when p21 was overproduced in the glioma cell lines irrespective o f p53 status.