RESUMO
PURPOSE: The importance of androgen receptor variants (AR-Vs) is recognized in prostate cancer. AR-Vs have been the focus of many studies. Expression of AR-Vs has been proposed as a biomarker for resistance to androgen deprivation therapy for metastatic disease. Herein, we show dynamic changes in AR-Vs expression in response to androgen modulation. METHODS: The C4-2B cell line was exposed to low (10-13 M) and high (10-8 M) androgen (dihydrotestosterone, DHT) levels, with or without flutamide. mRNA and protein expression levels were assessed by qPCR and immunohistochemistry, respectively. RESULTS: We demonstrated that high levels of DHT downregulate AR-FL and AR-Vs. Even though AR-Vs did not present ligand-binding domain, thus were not capable of binding to DHT, they present dynamic changes under androgen treatment. Treatment with flutamide alone or in association with low levels of DHT stimulates growth of prostatic cells. CONCLUSIONS: Importantly, we provide evidence that AR-Vs respond differently to androgenic modulation. These findings have implications for a better understanding of the role of AR-Vs in prostate carcinogenesis.
Assuntos
Androgênios/farmacologia , Proteínas Mutantes , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismo , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Ligantes , Masculino , Proteínas Mutantes/agonistas , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Polimorfismo Genético , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Isoformas de Proteínas/agonistas , Isoformas de Proteínas/metabolismoRESUMO
Xylella fastidiosa is responsible for a wide range of economically important plant diseases. We report here the crystal structure and kinetic data of Xylellain, the first cysteine protease characterized from the genome of the pathogenic X. fastidiosa strain 9a5c. Xylellain has a papain-family fold, and part of the N-terminal sequence blocks the enzyme active site, thereby mediating protein activity. One novel feature identified in the structure is the presence of a ribonucleotide bound outside the active site. We show that this ribonucleotide plays an important regulatory role in Xylellain enzyme kinetics, possibly functioning as a physiological mediator.