Lack of a correlation between p53 protein expression and radiation response in human tumor primary cultures.
We investigated the possible relationship between immunohistochemically detected p53 expression and in vitro response to gamma-irradiation in 24 primary cultures of human ovarian cancers and cutaneous melanomas. The frequency of p53-positive tumors was around 60% within each tumor histotype. The range of the surviving fraction at 2 Gy (SF2) was similar in p53-positive (0.10-0.76) and p53-negative (0.23-0.65) tumors, with median values of 0.36 and 0.33, respectively. No differences were observed in the accumulation of DNA-double strand breaks, assessed by neutral filter elution after exposure to 50 Gy, between p53-positive and p53-negative tumors. As regards DNA lesion repair, after 2 h of recovery the percentage of rejoined DNA-double strand breaks ranged from 19% to 99% in the different cultures, but again the distribution of values was similar for p53-positive and p53-negative tumors. Specifically, the median percentage of repaired DNA-double strand breaks was 70% and 74% in the two groups. On the whole, our data do not support the hypothesis that p53 overexpression is a major determinant of in vitro radiation response.
Zaffaroni
N
N
Istituto Nazionale per lo Studio e la Cura dei Tumori, Milano, Italy.
Benini
E
E
Gornati
D
D
Bearzatto
A
A
Silvestrini
R
R
D004249:DNA Damage; D004273:DNA, Neoplasm / Q000528:radiation effects; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008545:Melanoma / Q000532:radiotherapy*; D009362:Neoplasm Metastasis; D010051:Ovarian Neoplasms / Q000532:radiotherapy*; D014407:Tumor Cells, Cultured / Q000528:radiation effects*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D004273:DNA, Neoplasm; D016159:Tumor Suppressor Protein p53