Exploitable mechanisms for the blockade of androgenic action

Comparative effects of finasteride and laser-irradiated silver nanoparticles on testicular function and histology in testosterone induced benign prostatic hyperplasia in rats

AIMS

The objective of this study was to compare the effects of finasteride, a medication used to treat benign prostatic hyperplasia (BPH), and laser irradiated silver nanoparticles (AgNPs), a potential candidate for BPH therapy (Sanchez-Salas, 2017; Marghani et al., 2022) [1,2], on the sex hormone profiles, sperm quality, steroidogenesis, testicular oxidative stress, and histomorphology changes in BPH rats.

MATERIALS AND METHODS

BPH was induced in male Sprague-Dawley (SD) rats via intramuscular (i.m.) injection of 5 mg/kg BW testosterone propionate (TP) for 14 days. Once the BPH model was induced, rats were divided into four groups (n = 6) as follows: the control group; the BPH group; the BPH/Fina group, which received 5 mg/kg BW finasteride by oral gavage daily for 14 days; and the BPH/AgNPs group, which received a daily intraperitoneal (i.p.) injection of 50 mg/kg BW AgNPs, followed by 5 min of exposure to a 532 nm NIR laser in the prostatic area for the constitutive 14 days.

KEY FINDINGS

On day 14, the BPH rats had a significant increase in prostate specific antigen (PSA), dihydrotestosterone, and prostate weights, while testicular weights and sperm quality were significantly lower than in the control rats. On day 28, laser irradiated AgNps treated BPH rats showed improved sex hormone balance, testicular weights, sperm quality, steroidogenesis, and an ameliorative effect on testicular histopathology compared to finasteride.

SIGNIFICANCE

Surprisingly, these findings suggest that laser irradiated AgNPs can be used as an alternative therapy to finasteride for the treatment of BPH without causing negative effects on the testes.

Photothermal therapeutic potency of plasmonic silver nanoparticles for apoptosis and anti-angiogenesis in testosterone induced benign prostate hyperplasia in rats

AIMS

In this study, we used a near-infrared laser (NIR) to increase the potency of silver nanoparticles (AgNPs) to develop a novel, less invasive, and simple photothermal therapy technique for benign prostate hyperplasia (BPH).

MATERIALS AND METHODS

The shape, particle size, and zeta-potential of polyvinylpyrrolidone coated-AgNPs (PVP-AgNPs) were determined using transmission electron microscopy (TEM), Zeta-potential, and Particle size analyzer (ELSZ). To induce BPH, thirty-six male Sprague-Dawley (SD) rats were given intramuscular (i.m) injections of testosterone propionate (TP) at 5 mg/kg body weight (b.w)/day suspended in 0.1 ml of olive oil for 14 days. Photothermal therapy with AgNPs-NIR for 14 days was carried out. Prostate size, prostate index (PI), dihydrotestosterone (DHT), prostate-specific antigen (PSA), gross, hepatic, and renal toxicity, as well as antioxidant activity, apoptosis, and angiogenesis markers in prostatic tissues were measured. Histological examinations of prostates and biocompatibility of NIR-AgNPs on vital organs were also performed.

KEY FINDINGS

The aggregated spherical AgNPs with a mean size of 50-90 nm and a Zeta potential of -53.22 mV displayed high effectiveness in the NIR (532 nm-1 W) region by decreasing prostate size, PI, DHT, and PSA in BPH rats with no signs of gross, hepatic, or renal damage. As compared to alternative therapies, hyperthermia therapy increased antioxidant activities, induced apoptosis, inhibited angiogenesis, reduced histological alterations in the prostates of BPH rats, and improved biocompatibility of the vital organs.

SIGNIFICANCE

The current study demonstrated the effectiveness of plasmonic AgNPs photothermal therapy in the treatment of BPH.

ASC-J9(®) suppresses castration resistant prostate cancer progression via degrading the enzalutamide-induced androgen receptor mutant AR-F876L

Androgen deprivation therapy (ADT) with the newly developed powerful anti-androgen enzalutamide (Enz, also known as MDV3100) has promising therapeutic effects to suppress castration resistant prostate cancer (CRPC) and extending patients' lives an extra 4.8 months. However, most Enz therapy eventually fails with the development of Enz resistance. The detailed mechanisms how CRPC develops Enz resistance remain unclear and may involve multiple mechanisms. Among them, the induction of the androgen receptor (AR) mutant AR-F876L in some CRPC patients may represent one driving force that confers Enz resistance. Here, we demonstrate that the AR degradation enhancer, ASC-J9(®), not only degrades wild-type AR, but also has the ability to target AR-F876L. The consequence of suppressing AR-F876L may then abrogate AR-F876L mediated CRPC cell proliferation and metastasis. Thus, developing ASC-J9(®) as a new therapeutic approach may represent a novel therapy to better suppress CRPC that has already developed Enz resistance.

Treatment of benign prostatic hyperplasia with Croton membranaceus in an experimental animal model

ETHNOPHARMACOLOGICAL RELEVANCE

Croton membranaceus leaf extracts are used in the Bahamas to aromatize tobacco. In Nigeria it is used to improve digestion and in Ghana, the root extract is used for the treatment of benign prostatic hyperplasia (BPH). Despite claims of efficacy no data exists to support this. The aim of this study was to determine if Croton membranaceus aqueous root extract (CMARE) could attenuate the development of BPH in an animal model.

MATERIALS AND METHODS

Fifty (50) adult male Sprague-Dawley rats weighing 200-250g were randomly divided into 5 groups. Group 1 served as the control and received normal saline p.o. Groups 2-5 were castrated and injected with 5mg/kg b.wt. testosterone propionate subcutaneously for 28 days. Group 2 (model group) had no further treatment. Group 3 was simultaneously given 0.5mg/kg b.wt. finasteride p.o. throughout. Groups 4 and 5 received 30mg/kg b.wt. [low dose (LD)] and 300mg/kg b.wt. [high dose (HD)] CMARE, respectively, for 28 days. Rats were sacrificed at the end of the study and all prostate organs harvested. Wet weights, volumes and prostatic index (PI) were determined. Tissues were histologically examined. Serum prostate specific antigen (PSA) and dihydrotestosterone (DHT) levels were determined.

RESULTS

Prostate volume of the control group was 0.67±0.23cm(3). The model, finasteride, CMARE LD and HD groups had the following volumes: 0.92±0.12, 0.84±0.16, 0.79±0.16 and 0.80±0.19cm(3), respectively. Only the model group showed significant statistical differences with the control (p=0.007). PI for control, model, finasteride, LD and HD groups was as follows: 0.19±0.04, 0.30±0.04, 0.25±0.04, 0.21±0.05 and 0.22±0.05. No statistical differences between the control PI and the CMARE treated groups were observed. Histologically, the model group had massive growth of columnar stromal and epithelial cells. CMARE and finasteride attenuated this growth with a resultant thin layer of stromal and epithelial cells similar to the control. PSA levels were significantly lower in the treatment groups.

CONCLUSION

CMARE reduces stromal and epithelial cell growth, and subsequently shrinks enlarged prostate. This is the first scientific proof validating the anecdotal evidence of CMARE efficacy in the management of BPH.

Effects of Melandrium firmum methanolic extract on testosterone-induced benign prostatic hyperplasia in Wistar rats

Benign prostatic hyperplasia (BPH) is an age-related disease of unknown aetiology characterized by prostatic enlargement coincident with distinct alterations in tissue histomorphology. Instead of therapeutic agents that can cause severe side effects, plant extracts are frequently used to treat BPH. In this study, we investigated whether the Melandrium firmum methanolic extract (MFME) improves BPH, using the testosterone propionate (TP)-induced BPH rat model. Castration was performed via the scrotal route under sodium pentobarbital anaesthesia. BPH in castrated rats was generated via daily subcutaneous injections of TP (3 mg kg(-1)) dissolved in corn oil, for 4 weeks. MFME was administered daily by oral gavage at a dose of 200 mg kg(-1) for 4 weeks, along with the TP injections. The control group received injections of corn oil subcutaneously. At the scheduled termination of the experiment, all rats were killed and their prostates weighed; the relative prostate weight (prostate/body weight ratio) was calculated, and histomorphological changes in the prostate were examined. Additionally, we measured the levels of testosterone and dihydrotestosterone (DHT) in the serum and the prostate. Experimentally induced BPH led to marked decreases in the relative prostate weight and the DHT levels in the serum and the prostate. Histologically, BPH was evident in the ventral lobe of the prostate, and MFME treatment suppressed the severity of the lesions. These results indicate that MFME effectively inhibits the development of BPH induced by testosterone in a rat model. Further studies will be needed to identify the compound(s) responsibility for inducing the protective effect against BPH and determine its mechanism of action.

Steroid hormone receptors as targets for the therapy of breast and prostate cancer--recent advances, mechanisms of resistance, and new approaches

Surgical ovariectomy and orchiectomy, first proposed over a century ago, are effective in breast and prostate cancer therapy, respectively. Later, the discovery of steroid hormones and their nuclear receptors led to the concept that inhibition of steroid receptor function by an antagonist prevents tumour growth. While the first anti-hormones, cyproteroneacetate (CPA) and tamoxifen were found accidentally, deeper understanding of nuclear receptors as transcription factors enabled more rational, structure-activity based drug discovery. Results from a drug-finding program on pure anti-estrogens will be reported. These new steroidal anti-estrogens are highly active, pure ER-antagonists that lead to an efficient degradation of the estrogen receptor alpha (ERalpha) protein without any agonistic activity. Data obtained in preclinical tumour models in mice and rats showed a high potency in growth inhibition of ERalpha-positive breast cancer. In parallel, by comparing three independently generated anti-estrogen-resistant breast cancer cell lines, it was our intention to gain insight into the mechanisms of endocrine resistance which will allow to define new approaches for the treatment of endocrine-resistant breast cancer. Candidate proteins potentially involved in mechanisms of anti-estrogen-resistant growth of breast cancer cell lines were analyzed. ERalpha and progesterone receptor (PR) expressions were lost on the protein level in all three anti-estrogen-resistant cell lines, whereas binding of epidermal growth factor (EGF) and protein expression of epidermal growth factor receptor (EGFR) were increased. Loss of ERalpha expression may be linked to the acquisition of anti-estrogen resistance and enhanced expression of the EGFR and of members of the S100 family of Ca2+-binding proteins may contribute to the outgrowth of resistant cells. Furthermore, we describe the pharmacological development of a novel, highly potent progesterone receptor antagonist. In rat mammary tumour models, treatment with the PR antagonist completely suppressed the growth of established tumours and prevented the development of breast tumours. Advanced prostate cancer is effectively treated by androgen ablation. However, this therapy becomes inefficient although the androgen receptor (AR) is still functionally expressed. One novel strategy for the treatment of advanced prostate cancer could be the selective inhibition of AR protein expression by anti-sense oligonucleotides or small interfering RNA (siRNA) molecules. Down-regulation of the human AR caused significant inhibition of LNCaP prostate cancer growth in vivo. Taken together, many promising alternatives for endocrine therapy of breast and prostate cancer are arising.

Antiangiogenic effect of metronomic paclitaxel treatment in prostate cancer and non-tumor tissue in the same animals: a quantitative study

Well-tolerated continuous or metronomic chemotherapy can exert a marked antiangiogenic and thus superior antitumor effect compared with conventional high-dose, temporarily spaced-out chemotherapy, as shown in preclinical studies. There is, however, no means of directly assessing the antiangiogenic effect in a tumor, a serious impediment to assessing the effects of putative antiangiogenic chemotherapeutics or treatments. In an attempt to circumvent or minimize this impediment we studied the antiangiogenic effect of well-tolerated metronomic paclitaxel therapy in a surrogate tumor-free tissue that allows true quantitative analysis as well as in syngeneic At-1 prostate cancer in the same rat. This novel model allows an accurate comparison of the angiogenesis-modulating effect of chemotherapy in the two tissues to be made. The effect of chemotherapy on VEGF-A-mediated angiogenesis, a characteristic of most tumors, was assessed truly quantitatively by microscopic morphometry and image analysis in the tumor-free mesentery. The chemotherapy significantly suppressed VEGF-A-mediated angiogenesis in the mesentery to an extent that closely mirrored the significant increase in tumor necrosis measured morphometrically and the significant decrease in tumor growth rate. This finding opens an avenue to study quantitatively and systematically the antiangiogenic effect of chemotherapeutic modalities and treatments that approximately mirror their antiangiogenic effect in the At-1 tumor.