Silodosin inhibits noradrenaline-activated transcription factors Elk1 and SRF in human prostate smooth muscle

Innervation of the developing kidney in vivo and in vitro

Within the adult kidney, renal neurites can be observed alongside the arteries where they play a role in regulating blood flow. However, their role and localization during development has so far not been described in detail. In other tissues, such as the skin of developing limb buds, neurons play an important role during arterial differentiation. Here, we aim to investigate whether renal nerves could potentially carry out a similar role during arterial development in the mouse kidney. In order to do so, we used whole-mount immunofluorescence staining to identify whether the timing of neuronal innervation correlates with the recruitment of arterial smooth muscle cells. Our results show that neurites innervate the kidney between day 13.5 and 14.5 of development, arriving after the recruitment of smooth muscle actin-positive cells to the renal arteries.

Transient Astrocytic Gq Signaling Underlies Remote Memory Enhancement

Astrocytes elicit transient Ca2+ elevations induced by G protein-coupled receptors (GPCRs), yet their role in vivo remains unknown. To address this, transgenic mice with astrocytic expression of the optogenetic Gq-type GPCR, Optoα1AR, were established, in which transient Ca2+ elevations similar to those in wild type mice were induced by brief blue light illumination. Activation of cortical astrocytes resulted in an adenosine A1 receptor-dependent inhibition of neuronal activity. Moreover, sensory stimulation with astrocytic activation induced long-term depression of sensory evoked response. At the behavioral level, repeated astrocytic activation in the anterior cortex gradually affected novel open field exploratory behavior, and remote memory was enhanced in a novel object recognition task. These effects were blocked by A1 receptor antagonism. Together, we demonstrate that GPCR-triggered Ca2+ elevation in cortical astrocytes has causal impacts on neuronal activity and behavior.

Silodosin: An Update on Efficacy, Safety and Clinical Indications in Urology

INTRODUCTION

Silodosin determines smooth muscle relaxation in bladder and prostate tissues, increases bladder blood flow in conditions of chronic bladder ischemia and regulates the activity of transcriptional factors responsible for stromal growth and prostate hyperplasia. Phase III trials have already demonstrated the efficacy and safety of silodosin in the treatment of patients bothered by lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH).

OBJECTIVE

We aimed to describe the rationality for the use of silodosin and to summarize the current literature on the use of Silodosin for the treatment of LUTS.

METHODS

PubMed and Web of Science were queried with the terms: 'silodosin' in combination (AND) with the terms 'lower urinary tract symptoms', 'LUTS', 'pathophysiology', 'symptoms' OR 'therapy'. Studies published in the last 10 years (2007-2017) in adults and core clinical journals in English were included.

RESULTS

Silodosin 8 mg once-daily was superior to placebo in improving IPSS total score, voiding subscore, storage subscore and QoL score, and at least as effective as tamsulosin 0.4 mg once-daily in all the efficacy analyses. In addition, studies assessing the effect on urodynamic parameters showed that silodosin determined a higher improvement in the bladder outlet obstruction index compared to other alpha1 adrenergic receptor antagonists. Concerning the safety profile, long-term data (after 9 months of treatment) confirmed the limited effect of silodosin on the cardiovascular and gastrointestinal systems. Although ejaculatory disorders represented the main complaint of patients taking silodosin, the discontinuation rate due to this condition remained low even in a long-term follow-up study (7.5%). Encouraging findings showed that silodosin may be administered as a medical expulsive therapy for promoting spontaneous stone passage of distal ureteral stones < 10 mm, to relieve LUTS in patients who underwent prostate cancer brachytherapy and to increase the likelihood of successful trials without a catheter in patients experiencing acute urinary retention.

CONCLUSION

Silodosin is one of the drugs approved for the treatment of BPH, being highly effective in improving not only LUTS but also urodynamic parameter impairments secondary to BPH. Moreover, it has shown efficacy as medical expulsive therapy for distal ureteral stones in previous prospective randomized trials.

FUNDING

Sponsorship for this study and article processing charges were funded by Recordati.

ELK1 promotes urothelial tumorigenesis in the presence of an activated androgen receptor

We have recently demonstrated that ELK1, a transcription factor that triggers downstream targets including c-Fos proto-oncogene, promotes the growth of bladder cancer cells possessing a functional androgen receptor (AR). We here assessed the function of ELK1, as well as the efficacy of a selective α1A-adrenergic blocker silodosin that has been shown to inhibit ELK1 activity in bladder cancer cells, in urothelial tumorigenesis. The level of ELK1 expression in an immortalized normal urothelial cell line SVHUC stably expressing wild-type AR (SVHUC-AR) was considerably higher than that in AR-negative SVHUC-vector cells, which was induced further or reduced by dihydrotestosterone or silodosin treatment, respectively. In SVHUC-AR cells exposed to a chemical carcinogen 3-methylcholanthrene, silodosin significantly reduced the expression levels of oncogenes (e.g. c-Fos, Jun, Myc), as well as phospho-p38 MAPK and phospho-ERK proteins, and increased those of tumor suppressor genes (e.g. p53, PTEN, UGT1A). ELK1 suppression via ELK1-short hairpin RNA virus infection or silodosin treatment also resulted in significant inhibition in 3-methylcholanthrene-induced neoplastic transformation of SVHUC-AR cells, but not that of SVHUC-vector cells. In N-butyl-N-(4-hydroxybutyl)nitrosamine-treated male C57BL/6 mice, the incidence rate of bladder tumors was significantly (P = 0.007) lower in the silodosin group than in the control group. ELK1 thus appears to play a critical role in urothelial tumorigenesis, and silodosin prevents it presumably via down-regulation of ELK1. Moreover, ELK1 may require an activated AR for inducing neoplastic transformation of urothelial cells. Our findings may therefore offer a novel chemopreventive approach, via ELK1 inactivation using silodosin treatment, for bladder cancer.

Cellular Response to Titanium Dioxide Nanoparticles in Intestinal Epithelial Caco-2 Cells is Dependent on Endocytosis-Associated Structures and Mediated by EGFR

Titanium dioxide (TiO₂) is one of the most applied nanomaterials and widely used in food and non-food industries as an additive or coating material (E171). It has been shown that E171 contains up to 37% particles which are smaller than 100 nm and that TiO₂ nanoparticles (NPs) induce cytotoxicity and inflammation. Using a nuclear factor Kappa-light-chain enhancer of activated B cells (NF-κB) reporter cell line (Caco-2^nfkb-RE), Real time polymerase chain reaction (PCR), and inhibition of dynamin and clathrin, it was shown that cellular responses induced by 5 nm and 10 nm TiO₂ NPs (nominal size) depends on endocytic processes. As endocytosis is often dependent on the epithelial growth factor receptor (EGFR), further investigations focused on the involvement of EGFR in the uptake of TiO₂ NPs: (1) inhibition of EGFR reduced inflammatory markers of the cell (i.e., nuclear factor (NF)-κB activity, mRNA of IL8, CCL20, and CXCL10); and (2) exposure of Caco-2 cells to TiO₂ NPs activated the intracellular EGFR cascade beginning with EGFR-mediated extracellular signal-regulated kinases (ERK)1/2, and including transcription factor ELK1. This was followed by the expression of ERK1/2 target genes CCL2 and CXCL3. We concluded that TiO₂ NPs enter the cell via EGFR-associated endocytosis, followed by activation of the EGFR/ERK/ELK signaling pathway, which finally induces NF-κB. No changes in inflammatory response are observed in Caco-2 cells exposed to 32 nm and 490 nm TiO₂ particles.

Silodosin inhibits prostate cancer cell growth via ELK1 inactivation and enhances the cytotoxic activity of gemcitabine

BACKGROUND

Biological significance of ELK1, a transcriptional factor whose phosphorylation is necessary for c-fos proto-oncogene activation, in prostate cancer remains far from fully understood. In this study, we aim to investigate the role of ELK1 in tumor growth as well as the efficacy of a selective α1A-adrenergic blocker, silodosin, in ELK1 activity in prostate cancer cells.

METHODS

We first immunohistochemically determined the levels of phospho-ELK1 (p-ELK1) expression in radical prostatectomy specimens. We then assessed the effects of ELK1 knockdown via short hairpin RNA and silodosin on cell proliferation, migration, and invasion in prostate cancer lines.

RESULTS

The levels of p-ELK1 expression were significantly higher in carcinoma than in benign (P < 0.001) or high-grade prostatic intraepithelial neoplasia (HGPIN) (P = 0.002) as well as in HGPIN than in benign (P < 0.001). Kaplan-Meier and log-rank tests revealed that moderate-strong positivity of p-ELK1 in carcinomas tended to correlate with biochemical recurrence after radical prostatectomy (P = 0.098). In PC3 and DU145 expressing ELK1 (mRNA/protein) but no androgen receptor (AR), ELK1 silencing resulted in considerable decreases in the expression of c-fos as well as in cell migration/invasion and matrix metalloproteinase-2 expression, but not in cell viability. Silodosin treatment reduced the expression/activity of ELK1 in these cells as well as the viability of AR-positive LNCaP and C4-2 cells and the migration of both AR-positive and AR-negative cells, but not the viability of AR-negative or ELK1-negative cells. Interestingly, silodosin significantly increased sensitivity to gemcitabine, but not to cisplatin or docetaxel, even in AR-negative cells.

CONCLUSIONS

ELK1 is likely to be activated in prostate cancer cells and promote tumor progression. Furthermore, silodosin that inactivates ELK1 in prostate cancer cells not only inhibits their growth but also enhances the cytotoxic activity of gemcitabine. Thus, ELK1 inhibition has the potential of being a therapeutic approach for prostate cancer.

Silodosin inhibits the growth of bladder cancer cells and enhances the cytotoxic activity of cisplatin via ELK1 inactivation

Silodosin, a selective α1A-adrenergic blocker prescribed for the symptomatic treatment of benign prostatic hyperplasia, was previously shown to decrease the expression of ELK1, a c-fos proto-oncogene regulator and a well-described downstream target of the PKC/Raf-1/ERK pathway, in human prostate smooth muscle cells. PKC/Raf-1/ERK activation has also been implicated in drug resistance. In the current study, we assessed the effects of silodosin on ELK1 expression/activity in bladder cancer cells as well as on their proliferation in the presence or absence of chemotherapeutic drugs, including cisplatin and gemcitabine. In bladder cancer cell lines, silodosin reduced the expression of ELK1 (mRNA/protein) and its downstream target, c-fos gene, as well as the transcriptional activity of ELK1. While silodosin alone (up to 10 μM) insignificantly affected the growth of bladder cancer cells cultured in androgen depleted conditions or those expressing ELK1-short hairpin RNA, it considerably inhibited the viability of androgen receptor (AR)-positive/ELK1-positive cells in the presence of androgens. Silodosin also inhibited the migration of ELK1-positive cells with or without a functional AR, but not that of ELK1 knockdown cells. Interestingly, silodosin treatment or ELK1 silencing resulted in increases in drug sensitivity to cisplatin, but not to gemcitabine, even in AR-negative cells or AR-positive cells cultured in an androgen-depleted condition. In addition, silodosin decreased the expression of NF-κB, a key regulator of chemoresistance, and its transcriptional activity. Moreover, immunohistochemistry in bladder cancer specimens from patients who received neoadjuvant chemotherapy revealed that phospho-ELK1 positivity strongly correlated with chemoresistance. Silodosin was thus found to not only inhibit cell viability and migration but also enhance the cytotoxic activity of cisplatin in bladder cancer lines via inactivating ELK1. Our results suggest that combined treatment with silodosin is useful for overcoming chemoresistance in patients with ELK1-positive urothelial carcinoma receiving cisplatin.

Inhibition of smooth muscle force generation by focal adhesion kinase inhibitors in the hyperplastic human prostate

Smooth muscle contraction may be critical for lower urinary tract symptoms (LUTS) in patients with benign prostate hyperplasia and requires stable anchorage of the cytoskeleton to the cell membrane. These connections are regulated by focal adhesion kinase (FAK). Here, we addressed the involvement of FAK in the regulation of smooth muscle contraction in hyperplastic human prostate tissues. Prostate tissues were obtained from radical prostatectomy. Expression of FAK and focal adhesion proteins was assessed by Western blot analysis and immunohistochemical stainings. Effects of the FAK inhibitors PF-573228 and Y-11 on contraction of prostate strips were examined in the organ bath. Expression of FAK and focal adhesion proteins (integrin-5α, paxilin, and c-Src) was detected by Western blot analysis in prostate samples. By double immunofluorescence staining with calponin and pan-cytokeratin, expression of FAK was observed in stromal and epithelial cells. Immunoreactivity for FAK colocalized with integrin-5α, paxilin, talin, and c-Src. Stimulation of prostate tissues with the α1-adrenergic agonist phenylephrine increased the phosphorylation state of FAK at Tyr397 and Tyr925 with different kinetics, which was blocked by the α1-adrenoceptor antagonist tamsulosin. Norepinephrine and phenylephrine induced concentration-dependent contractions of prostate strips. Both FAK inhibitors PF-573228 and Y-11 significantly inhibited norepinephrine- and phenylephrine-induced contractions. Finally, PF-573228 and Y-11 inhibited contractions induced by electric field stimulation, which was significant at the highest frequency. In conclusion, α1-adrenergic smooth muscle contraction or its regulation involves FAK in the human prostate. Consequently, FAK may be involved in the pathophysiology of LUTS and in current or future LUTS therapies.