Abstract
Neoplastically transformed mouse and human keratinocytes elevate transactivation of both activator protein 1 (AP-1) and nuclear factor κB (NFκB) transcription factors. The present study addresses the question of whether elevated NFκB in addition to elevated AP-1-dependent gene expression is necessary for maintaining the tumor cell phenotype. When a tetracycline-regulatable dominant-negative c-jun (TAM67, having a truncated transactivation domain) was expressed in tumorigenic human keratinocytes, AP-1- and NFκB- but not p53-dependent reporter activity was inhibited by 40-60%. Tumor phenotype, as measured by anchorage-independent growth, was inhibited by 90%. Neither AP-1/NFκB activation nor expression of tumor phenotype was inhibited in TAM67-harboring keratinocytes under noninducing conditions. Electrophoretic mobility shift analysis showed that induction of TAM67 expression slightly increased AP-1- but reduced NFκB DNA-binding activity. Immunoprecipitation showed that TAM67 interacted in keratinocyte nuclei with NFκB p65, suggesting that inhibition of NFκB by TAM67 is mediated by direct protein-protein interactions, possibly producing decreased binding to DNA or inactivating p65. To analyze the putative effector genes that may be targeted by TAM67, expression of genes responsive to AP-1 or NFκB was measured by reverse transcriptase-polymerase chain reaction in TAM67 transfectants with or without TAM67 induction. Induction of TAM67 inhibited or reduced the expression of collagenase I, stromelysin I (AP-1 responsive), and interleukins 1 and 6 (NFκB responsive). These results indicate that genes controlled by NFκB and by AP-1 may be transformation-relevant targets of TAM67 and that TAM67 may inhibit NFκB activation through direct interaction with NFκB p65. Moreover, the findings provide proof for the principle of using inducible TAM67 as a gene therapy to suppress tumor phenotype in human carcinoma cells. Published 2000 Wiley-Liss, Inc.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 159-169 |
| Number of pages | 11 |
| Journal | Molecular Carcinogenesis |
| Volume | 29 |
| Issue number | 3 |
| DOIs | |
| State | Published - 2000 |
| Externally published | Yes |
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Keywords
- Activator protein 1
- Human keratinocytes
- Inducible transgene
- Neoplastic progression
- Nuclear factor κB
ASJC Scopus subject areas
- Cancer Research
- Molecular Biology
Cite this
Induced expression of dominant-negative c-jun downregulates NFκB and AP-1 target genes and suppresses tumor phenotype in human keratinocytes. / Li, Jian-Jian; Cao, Ya; Young, Mathew R.; Colburn, Nancy H.
In: Molecular Carcinogenesis, Vol. 29, No. 3, 2000, p. 159-169.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Induced expression of dominant-negative c-jun downregulates NFκB and AP-1 target genes and suppresses tumor phenotype in human keratinocytes
AU - Li, Jian-Jian
AU - Cao, Ya
AU - Young, Mathew R.
AU - Colburn, Nancy H.
PY - 2000
Y1 - 2000
N2 - Neoplastically transformed mouse and human keratinocytes elevate transactivation of both activator protein 1 (AP-1) and nuclear factor κB (NFκB) transcription factors. The present study addresses the question of whether elevated NFκB in addition to elevated AP-1-dependent gene expression is necessary for maintaining the tumor cell phenotype. When a tetracycline-regulatable dominant-negative c-jun (TAM67, having a truncated transactivation domain) was expressed in tumorigenic human keratinocytes, AP-1- and NFκB- but not p53-dependent reporter activity was inhibited by 40-60%. Tumor phenotype, as measured by anchorage-independent growth, was inhibited by 90%. Neither AP-1/NFκB activation nor expression of tumor phenotype was inhibited in TAM67-harboring keratinocytes under noninducing conditions. Electrophoretic mobility shift analysis showed that induction of TAM67 expression slightly increased AP-1- but reduced NFκB DNA-binding activity. Immunoprecipitation showed that TAM67 interacted in keratinocyte nuclei with NFκB p65, suggesting that inhibition of NFκB by TAM67 is mediated by direct protein-protein interactions, possibly producing decreased binding to DNA or inactivating p65. To analyze the putative effector genes that may be targeted by TAM67, expression of genes responsive to AP-1 or NFκB was measured by reverse transcriptase-polymerase chain reaction in TAM67 transfectants with or without TAM67 induction. Induction of TAM67 inhibited or reduced the expression of collagenase I, stromelysin I (AP-1 responsive), and interleukins 1 and 6 (NFκB responsive). These results indicate that genes controlled by NFκB and by AP-1 may be transformation-relevant targets of TAM67 and that TAM67 may inhibit NFκB activation through direct interaction with NFκB p65. Moreover, the findings provide proof for the principle of using inducible TAM67 as a gene therapy to suppress tumor phenotype in human carcinoma cells. Published 2000 Wiley-Liss, Inc.
AB - Neoplastically transformed mouse and human keratinocytes elevate transactivation of both activator protein 1 (AP-1) and nuclear factor κB (NFκB) transcription factors. The present study addresses the question of whether elevated NFκB in addition to elevated AP-1-dependent gene expression is necessary for maintaining the tumor cell phenotype. When a tetracycline-regulatable dominant-negative c-jun (TAM67, having a truncated transactivation domain) was expressed in tumorigenic human keratinocytes, AP-1- and NFκB- but not p53-dependent reporter activity was inhibited by 40-60%. Tumor phenotype, as measured by anchorage-independent growth, was inhibited by 90%. Neither AP-1/NFκB activation nor expression of tumor phenotype was inhibited in TAM67-harboring keratinocytes under noninducing conditions. Electrophoretic mobility shift analysis showed that induction of TAM67 expression slightly increased AP-1- but reduced NFκB DNA-binding activity. Immunoprecipitation showed that TAM67 interacted in keratinocyte nuclei with NFκB p65, suggesting that inhibition of NFκB by TAM67 is mediated by direct protein-protein interactions, possibly producing decreased binding to DNA or inactivating p65. To analyze the putative effector genes that may be targeted by TAM67, expression of genes responsive to AP-1 or NFκB was measured by reverse transcriptase-polymerase chain reaction in TAM67 transfectants with or without TAM67 induction. Induction of TAM67 inhibited or reduced the expression of collagenase I, stromelysin I (AP-1 responsive), and interleukins 1 and 6 (NFκB responsive). These results indicate that genes controlled by NFκB and by AP-1 may be transformation-relevant targets of TAM67 and that TAM67 may inhibit NFκB activation through direct interaction with NFκB p65. Moreover, the findings provide proof for the principle of using inducible TAM67 as a gene therapy to suppress tumor phenotype in human carcinoma cells. Published 2000 Wiley-Liss, Inc.
KW - Activator protein 1
KW - Human keratinocytes
KW - Inducible transgene
KW - Neoplastic progression
KW - Nuclear factor κB
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UR - http://www.scopus.com/inward/citedby.url?scp=0033646833&partnerID=8YFLogxK
U2 - 10.1002/1098-2744(200011)29:3<159::AID-MC5>3.0.CO;2-W
DO - 10.1002/1098-2744(200011)29:3<159::AID-MC5>3.0.CO;2-W
M3 - Article
VL - 29
SP - 159
EP - 169
JO - Molecular Carcinogenesis
JF - Molecular Carcinogenesis
SN - 0899-1987
IS - 3
ER -