Mallory-Denk bodies (MDBs) are found in the liver of patients with alcoholic and chronic
nonalcoholic liver disease, and hepatocellular carcinoma (HCC). Diethyl 1,4-dihydro-2,4,6,-trimethyl-3,5-pyridinedicarboxylate
(DDC) is used as a model to induce the formation of MDBs in mouse liver. Previous
studies in this laboratory showed that DDC induced epigenetic modifications in DNA
and histones. The combination of these modifications changes the phenotype of the
MDB forming hepatocytes, as indicated by the marker FAT10. These epigenetic modifications
are partially prevented by adding to the diet S-adenosylmethionine (SAMe) or betaine,
both methyl donors. The expression of three imprinted ncRNA genes was found to change
in MDB forming hepatocytes, which is the subject of this report. NcRNA expression
was quantitated by real-time PCR and RNA FISH in liver sections. Microarray analysis
showed that the expression of three ncRNAs was regulated by DDC: up regulation of
H19, antisense Igf2r (AIR), and down regulation of GTL2 (also called MEG3). S-adenosylmethionine
(SAMe) feeding prevented these changes. Betaine, another methyl group donor, prevented
only H19 and AIR up regulation induced by DDC, on microarrays. The results of the
SAMe and betaine groups were confirmed by real-time PCR, except for AIR expression.
After 1 month of drug withdrawal, the expression of the three ncRNAs tended toward
control levels of expression. Liver tumors that developed also showed up regulation
of H19 and AIR. The RNA FISH approach showed that the MDB forming cells' phenotype
changed the level of expression of AIR, H19 and GTL2, compared to the surrounding
cells. Furthermore, over expression of H19 and AIR was demonstrated in tumors formed
in mice withdrawn for 9 months. The dysregulation of ncRNA in MDB forming liver cells
has been observed for the first time in drug-primed mice associated with liver preneoplastic
foci and tumors.