Tp73 Dna Methylation And Upregulation Of Delta Np73 Are Associated With An Adverse Prognosis In Breast Cancer

Aim Accumulated evidence suggests that aberrant methylation of the TP73 gene and increased levels of Delta Np73 in primary tumours correlate with poor prognosis. However, little is known regarding the transcriptional and functional regulation of the TP73 gene in breast cancer. The aim of the present study was to determine the expression of the Delta Np73 isoform, its relationship with DNA methylation of TP73 and their clinical prognostic significance in breast cancer patients.Methods TP73 gene methylation was studied in TCGA datasets and in 70 invasive ductal breast carcinomas (IDCs). The expression of p73 isoforms was evaluated by immunohistochemistry (IHC) and Western blot and correlated with clinicopathological variables and clinical outcome.Results We observed that the methylation of diverse CpG islands of TP73 differed significantly between molecular subtypes. An inverse correlation was found between p73 protein expression and the methylation status of the TP73 gene. The expression of exon 3' of p73 (only expressed in Delta Np73) was significantly higher in patients with wild-type p53. Immunohistochemical analysis revealed that all p73 isoforms were localised in both the nuclear and cytoplasmic compartments. We confirmed a positive association between the expression of Delta Np73 and high histological grade.Conclusions Our findings suggest that high expression of Delta Np73 could be used to determine the aggressiveness of IDCs and could be incorporated in the pathologist's report.