Genomic alteration is not associated with fatty and clear cell change in hepatocellular carcinomas and its precursor nodular lesions in cirrhotic liver

Abstract

The aim of this study was to investigate whether fatty and clear cell areas in large regenerative nodules (LRN), dysplastic nodules (DN), and hepatocellular carcinoma (HCC) show higher degree of genomic mutation compared to non-fatty/clear cell area in the same nodule or non-lesional tissue. We examined 22 nodular lesions (9 HCC, 5 DN and 8 LRN) from seven cirrhotic livers removed at transplantation. Frozen sections were used for manual microdissection of areas with fatty/clear cell change. DNA from microdissected tissue was amplified using arbitrarily primed polymerase chain reaction (AP-PCR), and PCR products were run on polyacrilamide gel generating a "fingerprint" band pattern. Autoradiographs were analysed using Adobe Photoshop version 6.0. Fingerprints from lesional tissue were compared to reference tissue and the total number of bands in excess or defect was calculated and divided by the total number of bands identified, obtaining the genomic damage fraction (GDF). Increasing GDF average values were seen from cirrhotic liver (0.13+/-0.04), to LRN (0.16+/-0.1), DN (0.28+/-0.08) and HCC (0.30+/-0.07). A statistically significant difference in GDF values was documented between cirrhotic liver and DN (p=0.008) and HCC (p=0.005) and between HCC and LRN (p=0.02). No significant difference was documented between DN and HCC, and between LRN and cirrhotic liver. Eleven nodules containing fat/clear cell areas were compared to the other 11 nodules without fat/clear cell areas. The GDF was not different between the two groups: 0.29+/-0.11 versus 0.25+/-0.12; p=0.5. The average value of genomic damage fraction between fat/clear cell areas (0.29+/-0.11) and no fat/clear cell areas (0.25+/-0.1) within the same nodules were not significantly different (p=0.11). Fatty and clear cell change in nodular lesions in cirrhotic liver may be an epigenetic phenotypic modification caused by microenvironmental factors such as ischaemia rather than indicating areas of increased malignant potential per se.