Reduced expression and rare genomic alteration of nm23-H1 in human hepatocellular carcinoma and hepatoma cell lines

We investigated the expression and genomic alteration of nm23-H1 (which encodes a nucleoside diphosphate, kinase A) in 12 human hepatocellular carcinomas (HCCs) and four hepatoma cell lines. The expression of nm23-H1 protein was significantly reduced in HCCs with intrahepatic metastasis (72%) compared with expression in HCCs without intrahepatic metastasis (38%). However, in two of three HCCs examined that had marked reduction of nm23-H1 protein, the nm23-H1 mRNA level was not reduced. A hepatoma cell line, HLF (phenotype: poorly differentiated carcinoma) revealed marked reduction of nm23-H1 protein compared with two other hepatoma cell lines, HuH-1 and HuH-2, although the mRNA level was similar in the three cell lines. No allelic deletion of the nm23-H1 gene was detected in the 12 HCCs examined. No point mutation in the coding region of the nm23-H1 gene was observed in any of the 12 HCCs or the four hepatoma cell lines. These findings suggest that: (i) the expression of nm23-H1 protein is inversely associated with high metastatic potential of HCC: (ii) regulation of nm23-H1 expression may occasionally occur at both the transcriptional and post-transcriptional levels in HCC; and (iii) genomic alteration of nm23-H1 is a rare event in HCC.