This heterotransplant does not express either AR mRNA or the corresponding protein, similar to the androgen-independent PC-133 serially heterotransplanted tumour [62]. proliferation, metastatic potential and stromal and vascular components. These data are compared with the initial patient tumour specimen and, depending on available information, the patients clinical outcome was compared with the heterotransplanted tumour. The heterotansplant model is usually a more accurate preclinical model than older generation serially passaged or genetic models to investigate current and newly developed androgen-deprivation brokers, antitumour compounds, anti-angiogenic drugs and positron emission tomography radiotracers, as well as new therapeutic regimens for the treatment of PC. Keywords:experimental model, heterotransplant, nude mice, prostate, xenotransplant == Introduction == Prostate cancer (PC) is the second most common type of cancer among men in the United States, and it Rabbit Polyclonal to AKT1/3 is the second leading cause of cancer death in men. In 2009 2009, an estimated 192,280 men will be diagnosed with, and 27,360 men will die of PC [1]. There are several therapeutic approaches to treat PC. Surgery (radical prostatectomy) and radiotherapy are therapies with 5-12 months survival rates greater than 90%[2,3]. The most significant advance in PC therapy was the observation by Huggins and coworkers [4] that PC is usually a hormone-dependent disease. In this context, androgen deprivation therapy (ADT) can be achieved using several treatment options. Bilateral orchiectomy has response rates from 50% to 80%[5,6]; however, there are severe and irreversible side effects like loss of libido, impotence, hot flashes, osteoporosis and muscle wasting. In addition, ADT although temporarily effective as an antitumour therapy, androgen independent disease develops. In this case, ADT becomes only Platycodin D palliative. It Platycodin D is in this context the need for research and the development of relevant models for PC. ADT also may be achieved by treatment with oestrogens, like diethylstilbestrol (DES) or stilbestrol. Clinically, oestrogen therapy is based on the negative feedback loop of testosterone (T) regulation by inhibiting the release of luteinizing hormone-releasing hormone (LH-RH) in the hypothalamus. However, DES has severe side effects like cardiovascular and thromboembolic complications [7]. LH-RH agonists, such as leuprolide, goserelin and buserelin, are another group of drugs used for ADT. The sustained stimulation of the pituitary gonadotrope desensitized the LH-RH receptor (LH-RH-R), resulting in high levels of T in serum (flare phenomenon) initially, which soon fell to levels similar to those achieved by orchiectomy. Loss of libido, hot flashes and flare phenomenon are described side effects; pre-treatment with anti-androgens (AA) avoids the flare phenomenon. LH-RH antagonists inhibit the LH-RH-R, stopping the production of LH by pituitary gonodatrope cells and, subsequently, of T since, without LH stimulation, Leydig cells in the testis do not synthesize T. Cetrorelix, orgalutran and abarelix belong to this family of compounds. AA are another group of drugs used in ADT. The non-steroidal agonists block T and 5-dihydrotestosterone (DHT) from interacting with the cytosolic androgen receptor (AR), which is normally translocated into the nucleus, resulting in cell proliferation and inhibition of apoptosis. Also, in the pituitary gonadotrope may disassociate LH secretion from its negative feedback control, resulting in an elevation of LH and serum T levels. The serum T preserves libido and potency in patients. However, AA monotherapy (e.g.flutamide, bicatulamide and nilutamide), compared to orchiectomy, has an inferior response rate. The treatment of locoregionally advanced PC (stage T3) involves combination therapies. Radiation therapy combined with ADT, results in a significant improvement in patient progression-free survival [8]. However, radical prostatectomy combined with neoadjuvant ADT does not improve surgical outcome [9]. The management of persistent and recurrent disease after initial definitive therapy includes failure after Platycodin D radiation therapy, salvage surgery and ADT. Treatment options after radical prostatectomy failure include adjuvant radiation therapy in combination with ADT [10]. Approximately, less than 3% of PC will be metastatic at the time of diagnosis (stage T14NXM+) [11]. However, persistent and recurrent disease results in PC progression to androgen-independent disease and metastases. Unfortunately, docetaxel is the only chemotherapeutic agent in clinical use for this later stage of PC, combined with other antitumour agents like estramustine or prednisone [12]. In this context, development of new PC models is necessary. An interesting PC animal model is the transgenic adenocarcinoma of mouse prostate (TRAMP). However, TRAMP mice in addition to glandular tumours of the prostate, consistently develop phyllodes-like epethelial-stroma (ES) tumours, which may become fully malignant and metastasize [13]. In examining metastases from TRAMP mice, researchers must distinguish the tumour type to determine whether the tumour is metastatic from the seminal vesicle ES or from a glandular tumour of the prostate. In this case, the primary site may influence the interpretation of results [13]. There are increasing experimental data demonstrating that, in some cases, developing artificialin vitrocell lines from human cancers results in distinct and irreversible loss of important biological properties originally present in the tumour. In gene expression studies of small cell neuroendocrine carcinoma of the lung, some genes have been shown to undergo.