Differentiated rabbit prostatic stromal cells in primary culture display functional α1A-adrenoceptors

Animal models for benign prostatic hyperplasia

Although the etiology of benign prostatic hyperplasia (BPH) is unknown, various animal models have been used for several decades to identify potential therapeutic approaches. These models can be divided into those measuring smooth muscle tone and those measuring cellular proliferation. Animal models have played an important role in the development of the two drug classes currently approved for the treatment of BPH: the α-adrenoceptor antagonists and the steroid 5-α-reductase inhibitors. However, models measuring prostatic tone have not been particularly useful in the identification of new α-adrenoceptor antagonists having advantages over currently available drugs, and it is not certain that reduction of prostatic smooth muscle tone is responsible for the relief of BPH symptoms. A further limitation with BPH models is that prostatic hyperplasia similar to the human condition does not occur spontaneously or cannot be induced in any suitable animal species. The identification of a more useful BPH model is focused on cellular mechanisms of prostatic growth, looking similarities between humans and experimental animals.

Mechanisms of inhibition of human benign prostatic hyperplasia in vitro by the luteinizing hormone-releasing hormone antagonist cetrorelix

OBJECTIVE

To assess the mechanism by which the luteinizing hormone-releasing hormone (LHRH) antagonist cetrorelix exerts its effects in men with benign prostatic hyperplasia (BPH), as it produces a long-lasting improvement in lower urinary tract symptoms that is only partly accounted for by the transient reduction in testosterone levels, and the beneficial results could be due to direct inhibitory effects of cetrorelix on the prostate exerted through prostatic LHRH receptors.

MATERIALS AND METHODS

Using the BPH-1 cell line we evaluated the effects of cetrorelix in vitro on the proliferation and the expression of receptors for LHRH, epidermal growth factor (EGF), α(1A) -adrenergic receptor, STAT-3 transcription factor and the response to growth factors insulin-like growth factor (IGF)-1 and -II and fibroblast growth factor (FGF)-2.

RESULTS

There was expression of LHRH receptors in the human BPH-1 cell line. Cetrorelix had inhibitory effects on the proliferation rate of BPH-1 cells, also reflected by the decrease in the expression of the proliferating cell nuclear antigen (PCNA). Cetrorelix inhibited the stimulatory effect of the growth factors IGF-I and -II and FGF-2 on the proliferation of this line. Cetrorelix also downregulated the expression of the receptors for LHRH and EGF, as well as of α(1A) -adrenergic receptors, and inhibited the activation of the STAT3 transcription factor.

CONCLUSIONS

The results show that in vitro cetrorelix can directly inhibit the proliferation rate of the human BPH-1 cell line by counteracting growth factors like IGF-I and -II and FGF-2, and downregulating the LHRH receptor and α-adrenergic receptors, as well as transcription factors.