RESUMO
OBJECTS: The protein 300 (p300) and p300/CBP-binding protein-associated factor (PCAF) are enzymes with histone acetyltransferase (HAT) activity, a function that can become deregulated in different tumors and affect biological responses. METHODS: Due to the lack of information on the deregulation of these HATs in pediatric tumors, this study evaluated the expression of both the mRNA and proteins of p300 and PCAF in 54 samples of pediatric astrocytomas embedded in paraffin. RESULTS: PCAF was not expressed in normal brain tissue. In grade I tumors, the expression of p300 (1.1 ± 0.1) and PCAF (1.2 ± 0.11) was greater than those observed in grade III tumors: 0.72 ± 0.15 for p300 and 0.55 ± 0.11 for PCAF, and grade IV tumors: 0.74 ± 0.13 for p300 and 0.55 ± 0.13 for PCAF (p < 0.05). Immunohistochemical staining revealed the same tendency towards a decrease in the expression of the protein as the degree of clinical severity increased. Patients with recurrent grades I, III, and IV tumors had the highest levels of PCAF, compared to those who showed no recurrence (p < 0.05). CONCLUSIONS: This work describes and confirms that these HATs play important roles in regulating genes and in the biological behavior of pediatric astrocytomas.