RESUMEN
BACKGROUND: p53 deletion and mutation as well as upregulation of alpha-fetoprotein (AFP) are hallmarks of hepatocarcinogenesis. p63 and p73 belong to the family of p53-related transcription factors expressing a variety of isoforms. The expression of dominant negative (ΔN) p73 is related to the reduced survival of patients with hepatocellular carcinoma (HCC). In this study, we characterized the interaction between p53 family-dependent signaling pathways and the regulation of AFP at the gene and protein levels as essential determinants of therapeutic response and prognosis in HCC. METHODS: Putative p53-, p63- and p73-binding sites within the AFP gene were identified in silico. Hep3B cells were transfected with plasmids encoding for p53, p63 and p73 to analyze the interplay of the p53 family with AFP. AFP transcription was determined by RT-qPCR. Protein levels of AFP, p53, p63 and p73 were analyzed by Western blot. RESULTS: Underlining the importance of the crosstalk between the p53 family-dependent pathways and AFP regulation we identified eight novel putative binding sites for the members of the p53 family within the introns 1, 2, 3, 4, 7, 8, 11, and 12 of the AFP gene. Accordingly, full-length isoforms of p53, p63 and p73 efficiently downregulated AFP both on mRNA and protein level. Thus, the p53 family members were identified to be major regulators of AFP repression. Of note, p63 was characterized as a novel and p73 as the most efficient repressor of AFP. CONCLUSION: p53 mutation and upregulation of AFP are essential oncogenic events in the development of HCC. Here we show that AFP gene regulation occurs via a combined action of the p53 family members p53, p63 and p73. All three tumor suppressors reduce AFP gene and protein expression. Thus, our findings reveal a novel interaction of p53 family-dependent signaling pathways and AFP regulation at the gene and protein levels in HCC.
RESUMEN
BACKGROUND AND AIM: The aim of the study was to analyze the diagnostic performance and clinical utility of simple noninvasive tests for the detection of advanced fibrosis in patients with chronic hepatitis B (CHB) infection seen at a tertiary referral center in Germany. PATIENTS AND METHODS: We retrospectively analyzed 239 adult CHB patients with available liver biopsies. Patient demographics, hepatitis B markers, antiviral treatment, laboratory parameters, results from liver imaging, and histology were recorded. The sensitivity, specificity, and positive and negative predictive values were determined along with the area under receiver operating characteristic curves (AUROC) using published formulas and cut-off values for fibrosis index based on the four factors, aspartate aminotransferase-alanine aminotransferase ratio index (AAR), aspartate aminotransferase-to-platelet ratio index (APRI), and age-platelet index. RESULTS: The median documented duration of CHB infection was 31 months (range: 6-340 months); 86% of the patients were Caucasian and 71% were men. The AUROCs for the detection of advanced fibrosis were 0.75 [95% confidence interval (CI): 0.67-0.82], 0.72 (95% CI: 0.64-0.80), 0.48 (95% CI: 0.39-0.56), and 0.73 (95% CI: 0.66-0.81) for fibrosis index the four factors, APRI, AAR, and age-platelet index, respectively. Patients with advanced fibrosis on biopsy were misclassified as having mild fibrosis in 35% (APRI) to 82% (AAR) of cases. CONCLUSION: Because of their moderate test performance (AUROCs: 0.48-0.75) and their high misclassification rate, we could not confirm a reliable clinical utility for the analyzed noninvasive fibrosis scoring systems for the prediction of advanced fibrosis in mostly Caucasian CHB patients.
