Crosstalk between nicotine and estrogen-induced estrogen receptor activation induces α9-nicotinic acetylcholine receptor expression in human breast cancer cells.
The primary aim of this study was to elucidate the role of the estrogen receptor (ER), a transcription factor involved in the nicotine- and 17β-estradiol (E2)-mediated up-regulation of α9-nAChR gene expression. A real-time polymerase chain reaction (PCR) assay was used to quantify the α9-nAChR mRNA expression levels of surgically isolated (n=339) and laser-capture microdissected tissues (ER+ versus ER-, n= 6 per group). Chromatin immunoprecipitation (ChIP) and luciferase-promoter activity assays were used to investigate the ER-mediated transcriptional regulation of α9-nAChR gene expression. We observed that breast tumors with higher α9-nAChR mRNA expression levels (i.e., a mean fold ratio in the tumor/normal-paired samples of greater than tenfold) were associated with the lowest 5-year disease-specific survival rate (50%, dead/alive= 4/4, total = 8 patients, P= 0.006), in contrast to breast tumors with low levels (i.e., a mean fold ratio of less than onefold) of α9-nAChR expression (88%, dead/alive= 3/22, total= 25 patients). Furthermore, higher α9-nAChR mRNA expression levels were preferentially detected in ER+ tumor tissues in comparison to ER- tumor tissues (ER+ versus ER- patients: n=160 vs. 72; mean fold ratios of α9-nAChR expression = 11 ± 3 vs. 6.7 ± 2.3 fold, respectively). In vitro promoter-binding assays demonstrated that the ER is a major transcription factor that mediates nicotine- and E2-induced up-regulation of α9-nAChR gene expression in MCF-7 cells. In conclusion, our data indicate that the ER plays a central role in mediating α9-nAChR gene up-regulation in response to either nicotine or E2 stimulation.
Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
Chia-Hwa
CH
Lee
Ya-Chieh
YC
Chang
Ching-Shyang
CS
Chen
Shih-Hsin
SH
Tu
Ying-Jan
YJ
Wang
Li-Ching
LC
Chen
Yu-Jia
YJ
Chang
Po-Li
PL
Wei
Hui-Wen
HW
Chang
Chien-Hsi
CH
Chang
Ching-Shui
CS
Huang
Chih-Hsiung
CH
Wu
Yuan-Soon
YS
Ho
D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D047369:Chromatin Immunoprecipitation; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000819:agonists* / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D017930:Genes, Reporter; D006801:Humans; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D010766:Phosphorylation; D011379:Prognosis; D011401:Promoter Regions, Genetic; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020239:Receptor Cross-Talk; D011978:Receptors, Nicotinic / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D015996:Survival Rate; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation
C498540:CHRNA9 protein, human; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D018722:Nicotinic Agonists; D012333:RNA, Messenger; D011978:Receptors, Nicotinic; D018808:Transcription Factor AP-1; D004958:Estradiol; D009538:Nicotine; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases