Cáncer de próstata y apoptosis / Prostate Cancer and Apoptosis

El cáncer de próstata presenta una progresión andrógeno-dependiente mediada por el receptor de andrógeno (AR), por lo que el bloqueo androgénico es la terapia estándar para su tratamiento en estado avanzado. Sin embargo, a pesar de una sensibilidad inicial, estos cánceres usualmente evolucionan hacia un estado hormono-resistente. Esta resistencia puede ser debida a una amplificación del gen AR, a sus mutaciones y al aumento en la expresión de proteínas co-activadoras. Igualmente, el receptor AR puede permanecer activo, independientemente de la fijación del ligando por fosforilación de factores de crecimiento y de citosinas. Adicionalmente, hay otras posibles vías independientes del receptor AR, como lo ejemplifica la adquisición del fenotipo neuroendocrino. En esta revisión se examinan tanto los mecanismos moleculares involucrados en la progresión del cáncer de próstata así como la forma en que sus células evaden la apoptosis.

Prostate cancer presents an androgen-dependent growth mediated by the androgen receptor (AR). Androgen pathway blockage is the standard therapy for the treatment of prostate cancer at an advanced stage. In spite of an initial sensitivity, prostate cancer usually becomes refractory to hormone treatment. This resistance can be due to the amplification of the AR gene, AR mutations and the increase in co-activator protein expression. Likewise, growth factors and cytokines can induce AR phosphorylation, independently of ligand fixation. Moreover, there are other AR-independent pathways, such as the acquisition of the neuroendocrine phenotype. In this review, we examine the molecular mechanisms that are involved in the progression of prostate cancer, as well as the ways its cells evade apoptosis.

Recovery of hormone sensitivity after salvage brachytherapy for hormone refractory localized prostate cancer

PURPOSE: Recent work has demonstrated the return of hormone sensitivity after palliative chemotherapy in androgen independent prostate cancer. We wished to establish whether a similar phenomenon existed in patients with no exposure to chemotherapy. MATERIALS AND METHODS: A review of “hormone resistant” patients who had received salvage brachytherapy for localized prostate cancer after previous external beam radiotherapy was undertaken. Three patients with subsequent biochemical relapse responded to the rechallenge with hormonal treatment. RESULTS: The series of patients presented here demonstrates this phenomenon occurs after salvage brachytherapy with no exposure to chemotherapy. Recovery of sensitivity is demonstrated both to androgen deprivation and to androgen receptor antagonism. The recovery of hormone sensitivity was surprisingly durable, ranging from eight months to over twenty-one months. CONCLUSIONS: Hormone sensitivity may be recovered after salvage brachytherapy. Potential mechanisms underlying these observations are discussed and the likely central role of the activity of the androgen receptor highlighted. The relevance of these findings to the management of advanced prostate cancer is considered including thoughts on the practice of intermittent anti-androgen therapy.

Androgens and the male reproductive tract: an overview of classical roles and current perspectives: [review] / Androgênios e o trato reprodutor masculino: ações clássicas e perspectivas atuais: [revisão]

Androgens are steroid hormones that play key roles in the development and maintenance of male phenotype and reproductive function. These hormones also affect the function of several non-reproductive organs, such as bone and skeletal muscle. Endogenous androgens exert most of their effects by genomic mechanisms, which involve hormone binding to the androgen receptor (AR), a ligand-activated transcription factor, resulting in the modulation of gene expression. AR-induced non-genomic mechanisms have also been reported. A large number of steroidal and non-steroidal AR-ligands have been developed for therapeutic use, including the treatment of male hypogonadism (AR agonists) and prostate diseases (AR antagonists), among other pathological conditions. Here, the AR gene and protein structure, mechanism of action and AR gene homologous regulation were reviewed. The AR expression pattern, its in vivo regulation and physiological relevance in the developing and adult testis and epididymis, which are sites of sperm production and maturation, respectively, were also presented.

Os androgênios são hormônios esteroides com papel fundamental no desenvolvimento e na manutenção do fenótipo masculino e da função reprodutiva. Esses hormônios também afetam a função de diversos tecidos não reprodutivos, como, por exemplo, o ósseo e musculoesquelético. Os androgênios endógenos exercem a maioria de suas funções por mecanismo genômico, que envolve a ligação do hormônio ao receptor de androgênio (RA), um fator de transcrição ativado por ligante, o que resulta no controle da expressão gênica. Mecanismos não genômicos também têm sido associados aos efeitos induzidos pelo RA. Um grande número de ligantes do RA, esteroidais e não esteroidais, tem sido desenvolvido para o uso terapêutico, incluindo o tratamento do hipogonadismo masculino (agonistas do RA) e de doenças da próstata (antagonistas do RA), entre outras condições patológicas. Neste trabalho, foram discutidas as características estruturais básicas do RA (gene e proteína), os mecanismos de ação desse receptor, bem como aspectos relacionados à sua regulação homóloga. O padrão de expressão do RA, sua regulação in vivo e relevância fisiológica durante o desenvolvimento e a vida adulta na função do testículo e epidídimo, tecidos responsáveis pela produção e maturação de espermatozoides, respectivamente, também foram discutidos.

Hipospadias: Enfoque molecular y endocrinológico / Hypospadias: molecular and endocrinological focus

Las hipospadias son el arresta en el desarrollo ventral del pene. Puede ser una malformación que se presenta de forma aislada o asociada a otras alteraciones como lo es la presencia de una curvatura ventral anormal del pene, criptorquidia, hernias inguinales, entre otras. En todos los casos es importante considerar las hipospadias como un grado leve de feminización. Actualmente no existe prevención para el desarrollo de las hipospadias y el único manejo es la corrección quirúrgica de la lesión. Grandes avances se han logrado en el estudio de los procesos moleculares asociados en el desarrollo de las hipospadias. Los receptores androgénicos (RA), alteraciones endocrinas se han postulado como fenómenos influyentes en el desarrollo de ésta patología. El objetivo del presente artículo es determinar los eventos moleculares asociados en el desarrollo de las hipospadias.

Current status of endocrine therapy in localized prostate cancer: cure has become a strong possibility

It is clear that all available means should be taken to diagnose prostate cancer early and to use efficient therapy immediately in order to prevent prostate cancer from migrating to the bones where treatment becomes extremely difficult and cure or even long-term control of the disease is an exception. The only means of preventing prostate cancer from migrating to the bones and becoming incurable is efficient treatment at the localized stage of the disease. In fact, since radical prostatectomy, radiotherapy and brachytherapy can achieve cure in about 50 percent of cases, these approaches are all equally valid choices as first treatment of localized prostate cancer. However, in view of the current knowledge and available data, nowadays, androgen blockade should also be considered as first line treatment. While showing the high efficacy of hormonal therapy in localized prostate cancer, present knowledge clearly indicate that long-term treatment with the best available hormonal drugs, somewhat similar to the 5 years of Tamoxifen in breast cancer, is required for optimal control of prostate cancer. It is also clear from the data analyzed that combined androgen blockage alone could well be an efficient therapy of localized prostate cancer while it has already been recognized as the best therapy for metastatic disease. This paper presents and discusses the current knowledge available on the use and results of endocrine therapy in localized prostate cancer.

Fatores hormonais e genéticos na próstata normal e neoplásica / Hormonal and genetics factors in normal and neoplasic prostate

Recentemente, tem sido dada muita atenção para os efeitos proliferativos dos andrógenos nas células prostáticas. Isso tem despertado grande interesse no papel desses hormônios esteróides no desenvolvimento e manutenção tanto da próstata normal quanto maligna. Entretanto, até o presente, não tem sido identificada a relação exata entre os níveis hormonais e o risco de neoplasia. O complexo andrógeno-receptor, após associação com elementos no DNA que respondem ao hormônio, promove especificamente o crescimento da glândula. Já foi reconhecido que existe uma estreita ligação entre o seu padrão de sinalização citoplasmática e aquele desencadeado pelos fatores de crescimento. Muito progresso tem sido obtido a partir do estudo dessas interações o que pode levar ao desenvolvimento de novas e eficientes abordagens terapêuticas no câncer de próstata.