S. Tada et al., Interferon regulatory factor-1 gene abnormality and loss of growth inhibitory effect of interferon-alpha in human hepatoma cell lines, INT J ONCOL, 13(6), 1998, pp. 1207-1216
The effect of IFN-alpha on the growth of 5 hepatoma cell lines and a normal
liver-derived cell line were examined. IFN dose-dependently inhibited the
growth of cell lines except for HLE and PLC/PRF/5 in which the inhibition o
nly occurred at a high concentration over 10,000 IU/ml. IFN-alpha-treatment
induced the G(1) arrest of these cells according to upregulation of p21(WA
F-1) expression, which is induced in PLC/PRF/5 and HLE only at a high IFN c
oncentration. The receptor for IFN-alpha/beta was well expressed in all the
cell lines. DNA rearrangement of IRF-1 was detected in HLE and PLC/PRF/5 b
y Southern blotting, while IRF-2 gene was preserved. IFN-induced gene expre
ssions were compared between HCC-T, HCC-M and PLC/PRF/5. RT-PCR demonstrate
d that the full-length IRF-1 and -2 mRNA was transcribed in all cell lines,
but the mRNA amount of former gene in PLC/PRF/5 was less than that in HCC-
T and HCC-M, about 1/10 by competitive RT-PCR. The sequence analysis of IRF
-1 cDNA was performed and the full-length mRNA transcription was reconfirme
d in PLC/PRF/5, but no significant point mutation was detected. These resul
ts suggest that IFN-alpha inhibits hepatoma growth by increasing p21(WAF-1)
expression only when the IRF-1 gene is preserved normally.