Contribution of estrogen receptor alpha to oncogenic K-Ras-mediated NIH3T3 cell transformation and its implication for escape from senescence by modulating the p53 pathway.
We previously reported that enhanced transcriptional activation of estrogen receptor alpha (ERalpha) contributed to [(12)Val]K-Ras-mediated NIH3T3 cell transformation. Functional inactivation of ERalpha by a dominant negative mutant of ERalpha (DNER) in the presence of activated K-Ras 4B mutant arrested the cell cycle at G(0)/G(1), subsequently provoking replicative cell senescence, finally abrogating tumorigenic potential. p53-dependent up-regulation of p21 was implicated in this cell senescence induction. Alterations in the MDM2 protein in response to DNER accounted for this p21-mediated cell senescence induction. An oncogenic K-Ras 4B mutant significantly increased MDM2 proteins coprecipitated with p53, and suppressed p53 transcriptional activity. In turn, DNER exerted its function to decrease MDM2 proteins coprecipitated with p53, followed by the stimulation of p53 activity in the presence of the oncogenic K-Ras 4B mutant. In addition, overexpression of wild type ERalpha in NIH3T3 cells resulted in the significant increase in the MDM2 protein level and the resultant suppression of p53 transcriptional activity. Finally, we demonstrated that c-Jun expression overcame the suppression and resultant enhancement of p21 protein level in response to DNER. The data imply that the ERalpha-AP1 pathway activated by oncogenic K-Ras 4B mutant contributes to the NIH3T3 cells' transformation by modulating p53 transcriptional activity through MDM2.
Kato
Kiyoko
K
Department of Molecular Genetics, Division of Molecular and Cell Therapeutics Medical Institute of Bioregulation, Kyushu University, Tsurumihara 4546, Beppu, Oita, Japan. kkaktoh@tsurumi.beppu.kyushu-u.ac.jp
Horiuchi
Shinji
S
Takahashi
Akira
A
Ueoka
Yousuke
Y
Arima
Takahiro
T
Matsuda
Takao
T
Kato
Hidenori
H
Nishida Ji
Jun-ichi
J
Nakabeppu
Yusaku
Y
Wake
Norio
N
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D002471:Cell Transformation, Neoplastic; D016922:Cellular Senescence / Q000502:physiology; D017931:DNA Primers; D047628:Estrogen Receptor alpha; D011905:Genes, ras; D007150:Immunohistochemistry; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism / Q000502:physiology; D051736:Proto-Oncogene Proteins c-mdm2; D011960:Receptors, Estrogen / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism / Q000502:physiology*
D017931:DNA Primers; D047628:Estrogen Receptor alpha; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011960:Receptors, Estrogen; D016159:Tumor Suppressor Protein p53; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2