G. Tappero et al., EXPRESSION OF THE C-MYC PROTOONCOGENE PRODUCT IN CELLS INFECTED WITH THE HEPATITIS-DELTA VIRUS, Hepatology, 20(5), 1994, pp. 1109-1114
The intrahepatic accumulation of the c-myc protooncogene product was o
bserved on immunofluorescence in each of six patients with chronic hep
atitis delta virus infection who exhibited the hepatitis D antigen in
their livers. The c-myc product was stained in the same nuclei that co
ntained the hepatitis D antigen. C-myc was not observed in acute hepat
itis D or in cases of chronic hepatitis delta virus infection without
expression of the hepatitis D antigen. The protooncogene product was d
etected in only 1 of 32 viral and nonviral liver disorders unrelated t
o hepatitis delta virus. To confirm these observations, we transfected
HBsAg-positive (PCL/PRF/5) and HBsAg-negative (HepG2) transformed liv
er cell lines with a plasmid containing a hepatitis delta virus cDNA t
rimer under the control of the SV40 early enhancer/promoter sequences.
Whereas baseline c-myc expression was barely detectable in mock-trans
fected PLC/PRF/5 or HepG2 cells, strong c-myc nuclear fluorescence was
observed when these same cells were transfected with the hepatitis D
antigen expression vector. Similar results were obtained after infecti
on of HeLa cells with a recombinant vaccinia virus expressing the hepa
titis D antigen. Detection of c-myc mRNA sequences by means of in situ
hybridization suggested that the c-myc product accumulation was not d
ue to increased amounts of its mRNA. The c-myc protein accumulates sel
ectively in the livers of patients with chronic hepatitis delta virus
infection and in the same nuclei that contain the hepatitis D antigen.
The expression of c-myc in hepatitis D antigen-containing cells does
not require the presence of hepatitis B virus infection.