High expression of p300 is linked to aggressive features and poor prognosis of Nasopharyngeal Carcinoma

Background: Increased expression of transcriptional coactivator p300 has been observed in a variety of human cancers. However, the expression status of p300 protein/mRNA in nasopharyngeal carcinoma (NPC) tissues and its clinicopathologic/prognostic implication are poorly understood. Methods: In our study, mRNA and protein expression levels of p300 was explored by reverse transcription-polymerase chain reaction (RT-PCR), Western blotting (WB) and immunohistochemistry (IHC) in nasopharyngeal mucosal and NPC tissues. The data were analyzed by receiver operating characteristic (ROC) curve analysis, spearman's rank correlation, Kaplan-Meier plots and Cox proportional hazards regression model. Results: Up-regulated expression of p300 mRNA/p300 protein was detected in NPC tissues by RT-PCR and WB, when compared to nasopharyngeal mucosal tissues. Based on ROC curve analysis, the cutoff score for p300 high expression was defined when more than 35% of the tumor cells were positively stained. High expression of p300 was observed in 127/209 (60.7%) of NPCs. In NPCs, high expression of p300 was positively associated with later T classification, later N classification, distant metastasis and later clinical stage (P < 0.05). In univariate survival analysis, overexpression of p300 was found to be an indicator of progression-free (P = 0.002) and overall survival (P = 0.001) in NPCs. More importantly, p300 expression was evaluated as an independent prognostic factor for NPC in multivariate analysis (P = 0.036). Conclusions: Our findings support that high expression of p300 protein might be important in conferring a more aggressive behavior, and is an independent molecular marker for shortened survival time of patients with NPC.