Changes in the androgen levels in the ventral prostate of spontaneously hypertensive rats after castration

Analysis of salivary flow rate, biochemical composition, and redox status in orchiectomized spontaneously hypertensive rats

OBJECTIVE

This study aimed to analyze the salivary flow rate, biochemical composition, and redox status in orchiectomized spontaneously hypertensive rats (SHR) compared to normotensive Wistar rats.

DESIGN

Thirty-two young adult male SHR and Wistar (3-months-old) rats were randomly distributed into four groups; either castrated bilaterally (ORX) or underwent fictitious surgery (SHAM) as Wistar-SHAM, Wistar-ORX, SHR-SHAM, and SHR-ORX. Two months beyond castration, pilocarpine-induced salivary secretion was collected from 5-month-old rats to analyze salivary flow rate, pH, buffer capacity, total protein, amylase, calcium, phosphate, sodium, potassium, chloride, thiobarbituric acid reactive substances (TBARs), carbonyl protein, nitrite, and total antioxidant capacity.

RESULTS

The salivary flow rate was higher in the Wistar-ORX compared to the Wistar-SHAM group, while remaining similar between the SHR-SHAM and SHR-ORX groups. ORX did not affect pH and salivary buffer capacity in both strains. However, salivary total protein and amylase were significantly reduced in the Wistar-ORX and SHR-ORX compared to the respective SHAM groups. In both ORX groups, salivary total antioxidant capacity and carbonylated protein were increased, while lipid oxidative damage (TBARs) and nitrite concentration were higher only in the Wistar-ORX than in the Wistar-SHAM group. In the Wistar-ORX and SHR-ORX, the salivary calcium, phosphate, and chloride were increased while no change was detected in the SHAM groups. Only salivary buffering capacity, calcium, and chloride in the SHR-ORX adjusted to values similar to Wistar-SHAM group.

CONCLUSION

Hypertensive phenotype mitigated the orchiectomy-induced salivary dysfunction, since the disturbances were restricted to alterations in the salivary biochemical composition and redox state.

Contribution of Adrenal Glands to Intratumor Androgens and Growth of Castration-Resistant Prostate Cancer

PURPOSE

Tumor androgens in castration-resistant prostate cancer (CRPC) reflect de novo intratumoral synthesis or adrenal androgens. We used C.B.-17 SCID mice in which we observed adrenal CYP17A activity to isolate the impact of adrenal steroids on CRPC tumors in vivo.

EXPERIMENTAL DESIGN

We evaluated tumor growth and androgens in LuCaP35CR and LuCaP96CR xenografts in response to adrenalectomy (ADX). We assessed protein expression of key steroidogenic enzymes in 185 CRPC metastases from 42 patients.

RESULTS

Adrenal glands of intact and castrated mice expressed CYP17A. Serum DHEA, androstenedione (AED), and testosterone (T) in castrated mice became undetectable after ADX (all P < 0.05). ADX prolonged median survival (days) in both CRPC models (33 vs. 179; 25 vs. 301) and suppressed tumor steroids versus castration alone (T 0.64 pg/mg vs. 0.03 pg/mg; DHT 2.3 pg/mg vs. 0.23 pg/mg; and T 0.81 pg/mg vs. 0.03 pg/mg, DHT 1.3 pg/mg vs. 0.04 pg/mg; all P ≤ 0.001). A subset of tumors recurred with increased steroid levels, and/or induction of androgen receptor (AR), truncated AR variants, and glucocorticoid receptor (GR). Metastases from 19 of 35 patients with AR positive tumors concurrently expressed enzymes for adrenal androgen utilization and nine expressed enzymes for de novo steroidogenesis (HSD3B1, CYP17A, AKR1C3, and HSD17B3).

CONCLUSIONS

Mice are appropriate for evaluating adrenal impact of steroidogenesis inhibitors. A subset of ADX-resistant CRPC tumors demonstrate de novo androgen synthesis. Tumor growth and androgens were suppressed more strongly by surgical ADX than prior studies using abiraterone, suggesting reduction in adrenally-derived androgens beyond that achieved by abiraterone may have clinical benefit. Proof-of-concept studies with agents capable of achieving true "nonsurgical ADX" are warranted.

Low Testosterone Alters the Activity of Mouse Prostate Stem Cells

BACKGROUND

Low serum testosterone (low T) has been repeatedly linked to worse outcomes in men with newly diagnosed prostate cancer (PC). How low T contributes to these outcomes is unknown. Here we demonstrate that exposure to low T causes significant changes in the mouse prostate and prostate stem cells.

METHODS

Mice were castrated and implanted with capsules to achieve castrate, normal, or sub-physiological levels of T. After 6 weeks of treatment, LC-MS/MS was used to quantify the levels of T and dihydrotestosterone (DHT) in serum and prostate tissue. FACS was used to quantify the percentages of purported prostate stem and transit amplifying (TA) cells in mouse prostates. Prostate tissues were also stained for the presence of CD68+ cells and RNA was extracted from prostate tissue or specific cell populations to measure changes in transcript levels with low T treatment.

RESULTS

Despite having significantly different levels of T and DHT in the serum, T and DHT concentrations in prostate tissue from different T treatment groups were similar. Low T treatment resulted in significant alterations in the expression of androgen biosynthesis genes, which may be related to maintaining prostate androgen levels. Furthermore, the expression of androgen-regulated genes in the prostate was similar among all T treatment groups, demonstrating that the mouse prostate can maintain functional levels of androgens despite low serum T levels. Low T increased the frequency of prostate stem and TA cells in adult prostate tissue and caused major transcriptional changes in those cells. Gene ontology analysis suggested that low T caused inflammatory responses and immunofluorescent staining indicated that low T treatment led to the increased presence of CD68+ macrophages in prostate tissue.

CONCLUSIONS

Low T alters the AR signaling axis which likely leads to maintenance of functional levels of prostate androgens. Low T also induces quantitative and qualitative changes in prostate stem cells which appear to lead to inflammatory macrophage infiltration. These changes are proposed to lead to an aggressive phenotype once cancers develop and may contribute to the poor outcomes in men with low T. Prostate 77:530-541, 2017. © 2016 Wiley Periodicals, Inc.

Changes in Sexual Behavior of Orchidectomized Rats Under Influence of Allotransplantation of Testicular Interstitial Cell Suspension

Transplantation of hormone-producing cells is an experimental endocrine dysfunction treatment. The present study investigated the effects of orchidectomy (OE) and transplantation of interstitial cell suspension (ICS) on rat sexual behavior. Adult experimental animals were divided into two populations. One of these populations had sexual experience before the experiment and the other did not. Each population was divided into three groups: control group and two orchidectomized groups. One of the orchidectomized groups was treated with ICS, and the other was treated with the vehicle. The changes in the sexual behavior were investigated on the following parameters: mount latency (ML), intromission latency (IL), ejaculation latency (EL), mount frequency (MF), intromission frequency (IF), copulatory efficacy (CE), and IF/EL ratio. The investigation of these changes lasted 4 weeks after ICS transplantation. The parameters of sexual behavior reflected a decrease in sexual function after OE at the beginning of the observation, especially for the animals that did not have a sexual experience. However, it was shown that sexual activity increased in the following 4 weeks. We have indicated that the loss of gonads attenuated the capacity to acquire sexual experience; nonetheless, it did not mean that the animals completely lost this capacity. Transplantation of ICS facilitated the maintenance of male sexual behavior after OE, fractionally enlarged the size of regressed seminal vesicles of the animals, and increased the free testosterone (T) level. These findings suggest the ICS can be considered as a temporal source of androgens, which can facilitate a restoration of sexual activity.

Low systemic testosterone levels induce androgen maintenance in benign rat prostate tissue

Prostate cancer (PC) is both an age- and an androgen-dependent disease. Paradoxically, systemic levels of androgens decline with age as the risk of PC rises. While there is no correlation between systemic androgen levels and the risk of PC, systemic androgen levels do not reflect the levels of androgens in prostate tissue. In metastatic PC, changes in the androgen biosynthesis pathway during hormone therapy result in increased levels of androgens in cancer tissue and contribute to continued androgen receptor (AR) signaling. It is possible that similar changes occur in normal prostate tissue as androgen levels decline with age and that this contributes to tumorigenesis. In the present study, we sought to determine whether the rat prostate is able to maintain functional levels of androgens despite low serum testosterone levels. Rats were castrated and implanted with capsules to achieve castrate, normal, sub-physiological, and supra-physiological levels of testosterone. After 6 weeks of treatment, LC-MS/MS was used to quantify the levels of testosterone and dihydrotestosterone (DHT) in the serum and prostate tissue. Quantitative RT-PCR was used to quantify the expression of genes involved in the androgen/AR signaling axis. Despite significantly different levels of testosterone and DHT being present in the serum, testosterone and DHT concentrations in prostate tissue from different testosterone-treatment groups were very similar. Furthermore, the expression of androgen-regulated genes in the prostate was similar among all the testosterone-treatment groups, demonstrating that the rat prostate can maintain a functional level of androgens despite low serum testosterone levels. Low-testosterone treatment resulted in significant alterations in the expression of androgen biosynthesis genes, which may be related to maintaining functional androgen levels.

Local insulin-like growth factor-I of ventral prostate was upregulated during long-term castration and may function through the autocrine system

The insulin-like growth factor I (IGF-I) is one of the main mitogens and anti-apoptotic factors, which has an important role in cell proliferation, inhibiting cell death in prostate cancer (PCa), and may act as a replacement for androgen after castration. Characterizing the changes in local IGF-I levels in the prostate after castration, is therefore of great importance for doctors to guide and select therapy models after surgical castration in men with PCa. The present study was performed to detect IGF-I of local ventral prostate (VP) at intervals up to 24 weeks after castration by a combination of reverse transcriptase PCR, western-blot, immunohistochemistry and immunofluorescence. We found IGF-I to be decreased sharply after castration and that mRNA and protein levels reached their minimum at 2 days and 5 days, respectively. The level of IGF-I increased gradually and although mRNA levels remained high for longer than 2 weeks, protein levels remained high for longer than 4 weeks. The epithelium cells of VP express IGF-I and its receptor longer than 2 weeks after castration. These findings suggested that although IGF-I of local VP decreases sharply in short-stage castration, its levels increase gradually and remain at high levels at least until 24 weeks. IGF-I synthesized mainly from epithelial cells, which may function through the autocrine system longer than 2 weeks castration.