Anàlisi de lexpressió i dels mecanismes dacció del receptor destrògens beta en el càncer de pròstata
It is well known that estrogens regulate cell cycle progression, but the specific contributions and mechanisms of action of the estrogen receptor beta (ER?) remain elusive. In this work has been analyzed the levels of ER?1 and ER?2 throughout the cell cycle, as well as the mechanisms of action and the consequences of the over-expression of ER?1 in the human prostate cancer LNCaP cell line. Results of this work shows that ER?1 mRNA and protein expression increased from the G1 to the S phase and decreased before entering the G2/M phase, whereas ER?2 levels decreased during the S phase and increased again in the G2/M phase. ER?1 protein was detected in both the nuclear and non-nuclear fractions, and ER?2 was found in only the nuclear fractions. Regarding the mechanisms of action, endogenous ER? was able to activate transcription via ERE during the S phase in a ligand-dependent manner, whereas no changes in AP1 and NFkB transactivation were observed after exposure to estradiol or the specific inhibitor ICI 182,780. Over-expression of either wild type ER?1 or ER?1 mutated in the DNA-binding domain caused an arrest in early G1. This arrest was accompanied by the interaction of over-expressed ER?1 with c-Jun N-terminal protein Kinase 1 (JNK1) and the decrease in cyclin D1 expression. The administration of ICI abolishes the JNK1-ER?1 interaction, increases c-jun phosphorylation and cyclin D1 expression and allowed the cells to progress to late G1, where they became arrested. In conclusion, our results demonstrate that, in LNCaP prostate cancer cells, the expression of both ER? isoforms is differentially regulated during the cell cycle and that ER? regulates cell cycle by ERE-dependent mechanisms during the S-phase and ERE-independent signaling pathways during the G1-phase. Moreover, the G1-cell cycle arrest caused by ER?1 over-expression reinforces the idea that ER? behaves as a tumor suppressor gene.
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Advisor:Murell, Francina; Reventós, Jaume
School:Universitat Autónoma de Barcelona
Source Type:Master's Thesis
Keywords:408 departament de biologia cel lular i fisiologia
Date of Publication:02/09/2007