Correlation of immunohistochemical staining and mutations of p53 in human hepatocellular carcinoma

Mutations of the p53 tumor suppressor gene are common in hepatocellular car cinomas (HCCs). Detection of mutations by sequencing provides more informat ion than immunohistochemical staining, but the equipment needed and the tim e required make it less practical for use in large-scale studies or in stud ies in developing countries. The degree of correlation between results obta ined with these two methods has been studied in various tumors but has not been well-established in human HCCs. Paraffin sections of HCCs of 28 patien ts from Qidong, China were immunohistochemically stained using monoclonal a ntibody to p53. In addition, exons 5-8 of the p53 gene were sequenced in th ese HCCs. Of the 28 HCCs, nine had 0-9% of nuclei stained for p53, and 19 h ad 50-95% stained. Mutations in p53 exons 5-8 were found in 17/28 (61%) HCC s, including 15 at codon 249 (exon 7), one at codon 198 (exon 6), and one a t codon 175 (exon 5). Among these 17 cases with p53 mutations, 16 cases (94 %) had 50-95% of nuclei stained. Among 11 HCCs with no mutations by sequenc ing, 8 were also negative by immunohistochemistry (0-9% of nuclei stained) (73%) (the five HCCs with no staining whatsoever all had wild-type p53). Im munohistochemical staining to detect p53 mutations in human HCCs detected m ost mutations that were detected by sequencing (94% sensitivity, 73% specif icity), and this method is therefore suitable when sequencing cannot be per formed.