COMBINATION THERAPY WITH 5-FLUOROURACIL AND IFN-ALPHA-2A INDUCES A NONRANDOM INCREASE IN DNA FRAGMENTS OF LESS-THAN-3 MEGABASES IN HT29-COLON-CARCINOMA CELLS
Rw. Horowitz et al., COMBINATION THERAPY WITH 5-FLUOROURACIL AND IFN-ALPHA-2A INDUCES A NONRANDOM INCREASE IN DNA FRAGMENTS OF LESS-THAN-3 MEGABASES IN HT29-COLON-CARCINOMA CELLS, Clinical cancer research, 3(8), 1997, pp. 1317-1322
We have used pulsed-field gel electrophoresis to examine 5-fluorouraci
l (5FU)-induced DNA double-strand breaks (DSBs), both with and without
modulation by IFN-alpha 2a (IFN alpha), in HT29 human colon adenocarc
inoma cells, Although 24-h treatment with either 10 mu M 5FU or 500 un
its/ml IFN alpha did not result in significant DNA fragmentation, the
combination of 5FU + IFN alpha resulted in a significant increase in D
IVA DSBs versus either drug alone (P < 0.05), The pattern of fragmenta
tion induced by treatment with 5FU + IFN alpha was compared to that in
duced by gamma-radiation, which generates lesions at random sites, dig
estion with NotI restriction endonuclease, which cleaves at the specif
ic sequence 5'... GCGGCCGC... 3', and HhaI restriction endonuclease, w
hich cleaves at the specific sequence 5'... GCGC... 3', 5FU + IFN alph
a resulted in a specific pattern characterized by the accumulation of
fragments of <3 Mb in the absence of fragments of >3 Mb, which differe
d from that of gamma-radiation and restriction endonuclease digestion,
Because neither morphological nor DNA fragmentation characteristic of
apoptosis was observed after 5FU + IFN alpha treatment, the nonrandom
pattern of DSBs that was observed did not appear to be the result of
the initiation of programmed cell death within these cells.