Tumor HLA‐DR expression linked to early intrahepatic recurrence of hepatocellular carcinoma

The outcome of patients with hepatocellular carcinoma (HCC) remains poor because of the high frequency of intrahepatic recurrence (IHR), particularly early IHR within 1 year of hepatectomy. To search for genes involved in early IHR, we performed DNA microarray analysis in a training set of 33 HCCs and selected 46 genes linked to early IHR from approximately 6,000 genes by means of a supervised learning method. Gene selection was validated by a false discovery rate of 0.37%. The 46 genes included many immune response‐related genes, which were all downregulated in HCCs with early IHR. Four of these genes (HLA‐DRA, HLA‐DRB1, HLA‐DG and HLA‐DQA), encoding MHC class II antigens, were coordinately downregulated in HCCs with early IHR compared to levels in HCCs with nonrecurrence. A cluster analysis reproduced expression patterns of the 4 MHC class II genes in 27 blinded HCC samples. To localize the major site of production of HLA‐DR protein in the tumor, we used 50 frozen specimens from 50 HCCs. Immunofluorescence staining showed that HLA‐DR protein levels in tumor cells, but not in stromal cells, were associated with the transcription levels of HLA‐DRA determined by both DNA microarray analysis and real‐time quantitative reverse transcription‐PCR. Univariate analysis showed that tumor HLA‐DR protein expression, pTNM stage and venous invasion were associated with early IHR. Multivariate analysis showed that tumor HLA‐DR protein expression was one of the independent risk factors for early IHR, suggesting HLA‐DR protein potential as a biomarker and a molecular target for therapeutic intervention. © 2005 Wiley‐Liss, Inc.