In situ detection of insulin-like growth factor II (IGF2) and H19 gene expression in hepatocellular carcinoma

To assess the relationship between insulin-like growth factor II (IGF2) and H19 gene expression at the cellular level, we have examined the distribution of IGF2 and H19 mRNA by means of in situ hybridization in hepatic malignancies consisting of hepatocellular carcinoma (HCC), cholangiocellular carcinoma (CCC), and metastatic liver cancer (MLC). In HCC, 15 of 27 tumors (56%) and 11 of 27 tumors (41%) demonstrated increased IGF2 and H19 gene expression, respectively. Of 16 HCCs with increased expression of either IGF2 or H19, 10 tumors coexpressed both transcripts at comparable levels. Moreover, the spatiotemporal distribution and the cellular localization of the two gene transcripts were almost identical, suggesting the presence of a reciprocal relation between IGF2 and H19. In addition, 5 HCCs showed increased IGF2 expression without concomitant H19 expression, whereas 1 HCC showed increased H19 expression without IGF2 transcripts. However, 11 HCCs showed no IGF2 or H19 expression. On the other hand, neither IGF2 transcripts nor H19 transcripts were detected in 2 CCCs or 10 MLCs studied. The data suggest that IGF2 and/or H19 gene expression may be characteristic of some HCCs.