Mechanisms of downregulation of transfected E-cadherin cDNA during formation of invasive tumors in syngeneic mice.
Loss of E-cadherin expression has been observed both in experimental tumors and in human cancers and is related to invasiveness and poor differentiation. The E-cadherin-negative mouse mesenchymal tumor cell line MO4 was transfected with several plasmids expressing mouse E-cadherin cDNA. These plasmids differed from each other by the extent of E-cadherin-specific 3' untranslated region (UTR) sequences and by the use of different constitutive promoters. Transfectants were isolated that expressed functional E-cadherin in a homogeneous way. In syngeneic mice, such MO4-Ecad transfectants invariably produced malignant fibrosarcoma-like tumors, which were completely E-cadherin-negative at the protein level. Northern blotting revealed that E-cadherin mRNA expression was downregulated in some but not all MO4-Ecad tumors. Downregulation was caused by mRNA instability triggered by particular 3' UTR sequences. This in vivo downregulation of E-cadherin in malignant MO4-Ecad tumors turned out to be reversible and is likely to be mediated by host factors to be further identified.
Keirsebilck
A
A
Molecular Cell Biology Unit, Department of Molecular Biology, Flanders Interuniversity Institute for Biotechnology, University of Gent, Belgium.
Van Hoorde
L
L
Gao
Y
Y
De Bruyne
G
G
Bruyneel
E
E
Vermassen
P
P
Mareel
M
M
van Roy
F
F
D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D015820:Cadherins / Q000096:biosynthesis* / Q000502:physiology; D018076:DNA, Complementary; D015536:Down-Regulation; D005455:Fluorescent Antibody Technique; D051379:Mice; D009361:Neoplasm Invasiveness; D011233:Precipitin Tests; D012333:RNA, Messenger; D014162:Transfection; D014407:Tumor Cells, Cultured
D015820:Cadherins; D018076:DNA, Complementary; D012333:RNA, Messenger