Endogenous AP-1 levels necessary for oncogenic activity are higher than those sufficient to support normal growth.
We investigated the role of endogenous AP-1 in human tumor cell lines by introducing SupJunD-1, a dominant-negative mutant of AP-1, using vesicular stomatitis virus G protein (VSV-G)-pseudotyped retrovirus vectors. Single inoculation of six human tumor cell lines, originating from osteosarcomas, non-small cell lung carcinomas or cervical carcinomas, with recombinant SupJunD-1 virus at a high multiplicity of infection readily inhibited colony formation in soft agar. We detected no significant changes in expression levels of AP-1 components c-Jun or Fra-1, adhesion molecules CD44 or E-cadherin, or cell cycle regulator p53, which are encoded by genes previously reported to be under the control of AP-1 in some mouse or human cell lines. By varying the dosage of VSV-G-pseudotyped retrovirus, we were able to change the proviral copy number of supjunD-1 from 1 to approximately 10 and monitor suppression of endogenous AP-1 function as assessed by growth characteristics of the tumor cell lines, we found a SupJunD-1 dosage which significantly suppressed anchorage-independent growth without affecting the cellular growth in monolayer cultures at all. We conclude that endogenous AP-1 levels necessary for oncogenic activity are much higher than those sufficient to support normal growth.
Ui
M
M
Department of Gene Regulation, University of Tokyo, Tokyo 108-8639, Japan.
Mizutani
T
T
Takada
M
M
Arai
T
T
Ito
T
T
Murakami
M
M
Koike
C
C
Watanabe
T
T
Yoshimatsu
K
K
Iba
H
H
D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D015820:Cadherins / Q000096:biosynthesis; D002455:Cell Division; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005799:Genes, Dominant; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis; D008562:Membrane Glycoproteins; D051379:Mice; D009369:Neoplasms / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D012190:Retroviridae / Q000235:genetics; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis; D014759:Viral Envelope Proteins / Q000378:metabolism; D000099169:Fos-Related Antigen 1
D015820:Cadherins; D004247:DNA; D018960:Hyaluronan Receptors; D008562:Membrane Glycoproteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D016159:Tumor Suppressor Protein p53; D014759:Viral Envelope Proteins; D000099169:Fos-Related Antigen 1; C028391:G protein, vesicular stomatitis virus