Reduction of prostate cancer incidence by naftopidil, an α1-adrenoceptor antagonist and transforming growth factor-β signaling inhibitor

Effects of chronic stress on cancer development and the therapeutic prospects of adrenergic signaling regulation

Long-term chronic stress is an important factor in the poor prognosis of cancer patients. Chronic stress reduces the tissue infiltration of immune cells in the tumor microenvironment (TME) by continuously activating the adrenergic signaling, inhibits antitumor immune response and tumor cell apoptosis while also inducing epithelial-mesenchymal transition (EMT) and tumor angiogenesis, promoting tumor invasion and metastasis. This review first summarizes how adrenergic signaling activates intracellular signaling by binding different adrenergic receptor (AR) heterodimers. Then, we focused on reviewing adrenergic signaling to regulate multiple functions of immune cells, including cell differentiation, migration, and cytokine secretion. In addition, the article discusses the mechanisms by which adrenergic signaling exerts pro-tumorigenic effects by acting directly on the tumor itself. It also highlights the use of adrenergic receptor modulators in cancer therapy, with particular emphasis on their potential role in immunotherapy. Finally, the article reviews the beneficial effects of stress intervention measures on cancer treatment. We think that enhancing the body's antitumor response by adjusting adrenergic signaling can enhance the efficacy of cancer treatment.

Repurposed Drugs in Gastric Cancer

Gastric cancer (GC) is one of the major causes of death worldwide, ranking as the fifth most incident cancer in 2020 and the fourth leading cause of cancer mortality. The majority of GC patients are in an advanced stage at the time of diagnosis, presenting a poor prognosis and outcome. Current GC treatment approaches involve endoscopic detection, gastrectomy and chemotherapy or chemoradiotherapy in an adjuvant or neoadjuvant setting. Drug development approaches demand extreme effort to identify molecular mechanisms of action of new drug candidates. Drug repurposing is based on the research of new therapeutic indications of drugs approved for other pathologies. In this review, we explore GC and the different drugs repurposed for this disease.

Human Prostate Tissue MicroRNAs and Their Predicted Target Pathways Linked to Prostate Cancer Risk Factors

MicroRNAs are important in prostate cancer development, progression and metastasis. The aim of this study was to test microRNA expression profile in prostate tissue obtained from prostate cancer patients for associations with various prostate cancer related factors and to pinpoint the predicted target pathways for these microRNAs. Prostate tissue samples were obtained at prostatectomy from patients participating in a trial evaluating impact of pre-operative atorvastatin on serum prostate specific antigen (PSA) and Ki-67 expression in prostate tissue. Prostate tissue microRNA expression profiles were analyzed using OpenArray^® MicroRNA Panel. Pathway enrichment analyses were conducted for predicted target genes of microRNAs that correlated significantly with studied factors. Eight microRNAs correlated significantly with studied factors of patients after Bonferroni multiple testing correction. MiR-485-3p correlated with serum HDL-cholesterol levels. In atorvastatin-treated subjects, miR-34c-5p correlated with a change in serum PSA and miR-138-3p with a change in total cholesterol. In the placebo arm, both miR-576-3p and miR-550-3p correlated with HDL-cholesterol and miR-627 with PSA. In pathway analysis, these eight microRNAs related significantly to several pathways relevant to prostate cancer. This study brings new evidence from the expression of prostate tissue microRNAs and related pathways that may link risk factors to prostate cancer and pinpoint new therapeutic possibilities.

Classification of Clear Cell Renal Cell Carcinoma based on Tumor Suppressor Genomic Profiling

Clear cell renal cell carcinoma (ccRCC) is the most prevalent type of malignancy in adults. However, the clinical significance of tumor suppressor genes (TSG) is largely elusive. Herein, the expression profile TSGs and its clinical response in ccRCC were investigated. A total of 603 ccRCC samples from two cohorts (TCGA and ICGC) were retrieved in this study. Three molecular subtypes (C1, C2, and C3) were identified based on the TSGs expression profile in the TCGA dataset. Through Weighted Gene Correlation Network Analysis (WGCNA), six modules associated with three subtypes were identified. Pathway enrichment for the modules revealed that crucial pathways including p53 signaling and immune-related pathways were significantly enriched. We further focused on the relationship between immune infiltration level and subtypes, and found that subtype C1 was associated with higher immune infiltration level, subtype C2 was corresponding with medium immune infiltration level, whereas subtype C3 was correlated with lower immune infiltration level. Interestingly, C2 have a better survival outcome, while C1 and C3 showed a poor prognosis. Considering their survival difference, we then performed a differentially expression analysis between C2 and C1&3, and a total of 99 differentially expressed tumor suppressor genes (DETSGs) were identified. According to these DETSGs, 59 potential compounds with 28 mechanisms of action (MOA) were predicted using the Connectivity Map (CMap) database. Among these compounds, leflunomide, naftopidil, and ribavirin were the most prospective compounds for the treatment of ccRCC. In addition, we found that subtype C2 is more sensitive to sorafenib and sunitinib drugs, and C2 have more likelihood to be responded to immunotherapy. In summary, the three subtypes hinged on the tumor suppressor gene expression for ccRCC might contribute to understanding the underlying molecular mechanisms of ccRCC. Also, its potential compounds might offer guidelines for developing a novel treatment strategy of ccRCC.

Alpha-1 blocker use increased risk of subsequent renal cell carcinoma: A nationwide population-based study in Taiwan

Elevated Renal cell carcinoma (RCC) risk has been associated with the use of several antihypertensive medications but has not yet been elucidated in the populations prescribed alpha-1 blockers that are commonly used in the treatment of hypertension and lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS-BPH). The aim of the present study was to investigate the association between alpha-1 blocker use and the risk of developing RCC using a nationwide population-based database in Taiwan. Patients who were treated with alpha-1 blockers for at least 28 days were identified through the Taiwan National Health Insurance Research Database from 2000 to 2010. The unexposed participants were matched with the exposed cases according to age, sex, and index year at a ratio of 3:1. Cox proportional hazards regression, stratified by sex and comorbidities and adjusted for age, was performed to estimate hazard ratios (HRs) for the risk of subsequent RCC. Among 2,232,092 subjects, patients who received alpha-1 blocker treatment had a higher risk of RCC than the unexposed group. Taking into account hypertension and BPH, the adjusted HR was significantly higher in male alpha-1 blocker users who had no BPH and either the presence (HR: 1.63, 95% confidence interval [CI] = 1.22–2.18) or absence (HR: 2.31, 95% CI = 1.40–3.81) of hypertension than in men not receiving these drugs. Taken together, male alpha-1 blocker users who had no comorbidity of BPH exhibited an increased risk for developing RCC independent of hypertension. Further study is warranted to elucidate the underlying mechanisms of this association.

Impact of Concomitant Medications on Biochemical Outcome in Localised Prostate Cancer Treated with Radiotherapy and Androgen Deprivation Therapy

AIMS

Several classes of concomitant medications have been shown to affect oncological outcomes in patients with prostate cancer (PCa). We assessed the association between the use of commonly prescribed concomitant medications and biochemical relapse-free survival (bRFS) in patients with localised PCa treated with radiotherapy and androgen deprivation therapy (ADT).

MATERIALS AND METHODS

A secondary pooled analysis of two phase III randomised trials was carried out. In the first trial, patients with localised PCa with clinical stage T1b-T3, prostate-specific antigen <30 ng/ml and Gleason score ≤7 were treated with radical radiotherapy and 6 months of ADT starting 4 months before or concomitantly with radiotherapy. In the second trial, patients with high-risk PCa were treated with radical radiotherapy and 36 months of ADT with randomisation to three-dimensional conformal or intensity-modulated radiotherapy. Information on concomitant medications was collected from the medical record. Univariable and multivariable Cox regression was used to identify factors associated with bRFS.

RESULTS

Overall, 486 patients were evaluable. The median follow-up was 125 months; 10-year bRFS was 83.7%. On univariable analysis, receipt of metformin was significantly associated with worse bRFS. Ten-year bRFS was 73% and 85% for patients with and without concomitant metformin (adjusted hazard ratio 2.11, 95% confidence interval 1.03-4.33). Similar evidence of an association was observed with sulfonamide-based α1-receptor blockers (adjusted hazard ratio 2.72, 95% confidence interval 1.31-5.66). However, no such association was seen with receipt of quinazoline-based α1-receptor blockers (adjusted hazard ratio 1.09, 95% confidence interval 0.42-2.82). There was no significant association between bRFS and receipt of all other medication classes considered.

CONCLUSIONS

In this population of patients with localised PCa treated with radiotherapy and ADT, receipt of concomitant metformin and sulfonamide-based α1-receptor blockers was associated with inferior biochemical outcome. Randomised trials are required to assess the true effect of these medications on oncological outcomes in localised PCa.

Drug Repositioning of the α1-Adrenergic Receptor Antagonist Naftopidil: A Potential New Anti-Cancer Drug?

Failure of conventional treatments is often observed in cancer management and this requires the development of alternative therapeutic strategies. However, new drug development is known to be a high-failure process because of the possibility of a lower efficacy than expected for the drug or appearance of non-manageable side effects. Another way to find alternative therapeutic drugs consists in identifying new applications for drugs already approved for a particular disease: a concept named "drug repurposing". In this context, several studies demonstrated the potential anti-tumour activity exerted by α1-adrenergic receptor antagonists and notably renewed interest for naftopidil as an anti-cancer drug. Naftopidil is used for benign prostatic hyperplasia management in Japan and a retrospective study brought out a reduced incidence of prostate cancer in patients that had been prescribed this drug. Further studies showed that naftopidil exerted anti-proliferative and cytotoxic effects on prostate cancer as well as several other cancer types in vitro, as well as ex vivo and in vivo. Moreover, naftopidil was demonstrated to modulate the expression of Bcl-2 family pro-apoptotic members which could be used to sensitise cancer cells to targeting therapies and to overcome resistance of cancer cells to apoptosis. For most of these anti-cancer effects, the molecular pathway is either not fully deciphered or shown to involve α1-adrenergic receptor-independent pathway, suggesting off target transduction signals. In order to improve its efficacy, naftopidil analogues were designed and shown to be effective in several studies. Thereby, naftopidil appears to display anti-cancer properties on different cancer types and could be considered as a candidate for drug repurposing although its anti-cancerous activities need to be studied more deeply in prospective randomized clinical trials.

TGF-β causes Docetaxel resistance in Prostate Cancer via the induction of Bcl-2 by acetylated KLF5 and Protein Stabilization

Prostate cancer is the second leading cause of cancer-related death in the United States. As a first line treatment for hormone-refractory prostate cancer, docetaxel (DTX) treatment leads to suboptimal effect since almost all patients eventually develop DTX resistance. In this study, we investigated whether and how TGF-β affects DTX resistance of prostate cancer.

Methods: Cytotoxicity of DTX in DU 145 and PC-3 cells was measured by CCK-8 and Matrigel colony formation assays. Resistance to DTX in DU 145 cells was examined in a xenograft tumorigenesis model. A luciferase reporter system was used to determine transcriptional activities. Gene expression was analyzed by RT-qPCR and Western blotting.

Results: We found that KLF5 is indispensable in TGF-β-induced DTX resistance. Moreover, KLF5 acetylation at lysine 369 mediates DTX resistance in vitro and in vivo. We showed that the TGF-β/acetylated KLF5 signaling axis activates Bcl-2 expression transcriptionally. Furthermore, DTX-induced Bcl-2 degradation depends on a proteasome pathway, and TGF-β inhibits DTX-induced Bcl-2 ubiquitination.

Conclusion: Our study demonstrated that the TGF-β-acetylated KLF5-Bcl-2 signaling axis mediates DTX resistance in prostate cancer and blockade of this pathway could provide clinical insights into chemoresistance of prostate cancer.

Bim, Puma and Noxa upregulation by Naftopidil sensitizes ovarian cancer to the BH3-mimetic ABT-737 and the MEK inhibitor Trametinib

Ovarian cancer represents the first cause of mortality from gynecologic malignancies due to frequent chemoresistance occurrence. Increasing the [BH3-only Bim, Puma, Noxa proapoptotic]/[Bcl-x_L, Mcl-1 antiapoptotic] proteins ratio was proven to efficiently kill ovarian carcinoma cells and development of new molecules to imbalance Bcl-2 member equilibrium are strongly required. Drug repurposing constitutes an innovative approach to rapidly develop therapeutic strategies through exploitation of established drugs already approved for the treatment of noncancerous diseases. This strategy allowed a renewed interest for Naftopidil, an α₁-adrenergic receptor antagonist commercialized in Japan for benign prostatic hyperplasia. Naftopidil was reported to decrease the incidence of prostate cancer and its derivative was described to increase BH3-only protein expression in some cancer models. Based on these arguments, we evaluated the effects of Naftopidil on ovarian carcinoma and showed that Naftopidil reduced cell growth and increased the expression of the BH3-only proteins Bim, Puma and Noxa. This effect was independent of α₁-adrenergic receptors blocking and involved ATF4 or JNK pathway depending on cellular context. Finally, Naftopidil-induced BH3-only members sensitized our models to ABT-737 and Trametinib treatments, in vitro as well as ex vivo, in patient-derived organoid models.

A Pilot retrospective analysis of alpha-blockers on recurrence in men with localised prostate cancer treated with radiotherapy

While alpha-blockers are commonly used to reduce lower urinary tract symptoms in prostate cancer patients receiving radiotherapy, their impact on response to radiotherapy remains unknown. Therefore, this pilot study aimed to retrospectively determine if alpha-blockers use, influenced response to radiotherapy for localised prostate cancer. In total, 303 prostate cancer patients were included, consisting of 84 control (alpha-blocker naïve), 72 tamsulosin and 147 prazosin patients. The main outcomes measured were relapse rates (%), time to biochemical relapse (months) and PSA velocity (ng/mL/year). Recurrence free survival was calculated using Kaplan-Meier analysis. Prazosin significantly reduced biochemical relapse at both two and five-years (2.72%, 8.84%) compared to control (22.61%, 34.52%). Recurrence free survival was also significantly higher in the prazosin group. This remained after multivariable analysis (HR: 0.09, 95% CI: 0.04-0.26, p < 0.001). Patients receiving prazosin had a 3.9 times lower relative risk of biochemical relapse compared to control. Although not statistically significant, tamsulosin and prazosin extended recurrence free survival by 13.15 and 9.21 months respectively. We show for the first time that prazosin may reduce risk of prostate cancer recurrence and delay time to biochemical relapse and provides justification for prospective studies to examine its potential as an adjunct treatment option for localised prostate cancer.

Identification of HUHS190, a human naftopidil metabolite, as a novel anti-bladder cancer drug

We carried out structure-activity relationship study on anti-cancer effects of naftopidil (1) and its metabolites, resulted in identification of 1-(4-hydroxy-2-methoxyphenyl)piperazin-1-yl)-3-(naphthalen-1-yloxy) propan-2-ol (2, HUHS190), a major human metabolite of 1, which exhibited the most selective toxicities between against normal and cancer cells (Table 1). 2 was more hydrophilic compared to 1, was enough to be prepared in high concentration solution of more than 100 μM in saline for an intravesical instillation drug. Moreover, serum concentration of 2 was comparable to that of 1, an oral preparation drug, after oral administration at 32 mg/kg (Fig. 3). Both of 1 and 2 showed broad-spectrum anti-cancer activities in vitro, for example, 1 and 2 showed inhibitory activity IC₅₀ = 21.1 μM and 17.2 μM for DU145, human prostate cancer cells, respectively, and IC₅₀ = 18.5 μM and 10.5 μM for T24 cells, human bladder cancer cells. In this study, we estimated anticancer effects of 2 in a bladder cancer model after intravesical administration similar to clinical cases. A single intravesical administration of 2 exhibited the most potent inhibitory activities among the clinical drugs for bladder cancers, BCG and Pirarubicin, without obvious side effects and toxicity (Fig. 4). Thus, HUHS190 (2) can be effective for patients after post-TURBT therapy of bladder cancer without side effects, unlike the currently available clinical drugs.

Naftopidil reduced the proliferation of lung fibroblasts and bleomycin-induced lung fibrosis in mice

Naftopidil, an α‐1 adrenoceptor antagonist with few adverse effects, is prescribed for prostate hyperplasia. Naftopidil inhibits prostate fibroblast proliferation; however, its effects on lung fibroblasts and fibrosis remain largely unknown. Two normal and one idiopathic pulmonary fibrosis human lung fibroblast lines were cultured with various naftopidil concentrations with or without phenoxybenzamine, an irreversible α‐1 adrenoceptor inhibitor. We examined the incorporation of 5‐bromo‐2ʹ‐deoxyuridine into DNA and lactic acid dehydrogenase release by enzyme‐linked immunosorbent assay, cell cycle analysis by flow cytometry, scratch wound‐healing assay, and mRNA expressions of type IV collagen and α‐smooth muscle actin by polymerase chain reaction. Effects of naftopidil on bleomycin‐induced lung fibrosis in mice were evaluated using histology, micro‐computed tomography, and surfactant protein‐D levels in serum. Naftopidil, dose‐dependently but independently of phenoxybenzamine, inhibited 5‐bromo‐2ʹ‐deoxyuridine incorporation in lung fibroblasts. Naftopidil induced G1 cell cycle arrest, but lactic acid dehydrogenase release and migration ability of lung fibroblasts were unaffected. Naftopidil decreased mRNA expressions of type IV collagen and α‐smooth muscle actin in one normal lung fibroblast line. Histological and micro‐computed tomography examination revealed that naftopidil attenuated lung fibrosis and decreased serum surfactant protein‐D levels in bleomycin‐induced lung fibrosis in mice. In conclusion, naftopidil may have therapeutic effects on lung fibrosis.

Effects of High Concentrations of Naftopidil on Dorsal Root-Evoked Excitatory Synaptic Transmissions in Substantia Gelatinosa Neurons In Vitro

Purpose

Naftopidil ((±)-1-[4-(2-methoxyphenyl) piperazinyl]-3-(1-naphthyloxy) propan-2-ol) is prescribed in several Asian countries for lower urinary tract symptoms suggestive of benign prostatic hyperplasia. Previous animal experiments showed that intrathecal injection of naftopidil abolished rhythmic bladder contraction in vivo. Naftopidil facilitated spontaneous inhibitory postsynaptic currents in substantia gelatinosa (SG) neurons in spinal cord slices. These results suggest that naftopidil may suppress the micturition reflex at the spinal cord level. However, the effect of naftopidil on evoked excitatory postsynaptic currents (EPSCs) in SG neurons remains to be elucidated.

Methods

Male Sprague-Dawley rats at 6 to 8 weeks old were used. Whole-cell patch-clamp recordings were made using SG neurons in spinal cord slices isolated from adult rats. Evoked EPSCs were analyzed in Aδ or C fibers. Naftopidil or prazosin, an α1-adrenoceptor blocker, was perfused at 100 μM or 10 μM, respectively.

Results

Bath-applied 100 μM naftopidil significantly decreased the peak amplitudes of Aδ and C fiber-evoked EPSCs to 72.0%±7.1% (n=15) and 70.0%±5.5% (n=20), respectively, in a reversible and reproducible manner. Bath application of 10μM prazosin did not inhibit Aδ or C fiber-evoked EPSCs.

Conclusions

The present study suggests that a high concentration of naftopidil reduces the amplitude of evoked EPSCs via a mechanism that apparently does not involve α1-adrenoceptors. Inhibition of evoked EPSCs may also contribute to suppression of the micturition reflex, together with nociceptive stimulation.

Partial agonist activity of α1-adrenergic receptor antagonists for chemokine (C-X-C motif) receptor 4 and atypical chemokine receptor 3

We observed in PRESTO-Tango β-arrestin recruitment assays that the α₁-adrenergic receptor (AR) antagonist prazosin activates chemokine (C-X-C motif) receptor (CXCR)4. This prompted us to further examine this unexpected pharmacological behavior. We screened a panel of 14 α_1/2- and β_1/2/3-AR antagonists for CXCR4 and atypical chemokine receptor (ACKR)3 agonist activity in PRESTO-Tango assays against the cognate agonist CXCL12. We observed that multiple α₁-AR antagonists activate CXCR4 (CXCL12 = prazosin = cyclazosin > doxazosin) and ACKR3 (CXCL12 = prazosin = cyclazosin > alfuzosin = doxazosin = phentolamine > terazosin = silodosin = tamsulosin). The two strongest CXCR4/ACKR3 activators, prazosin and cyclazosin, were selected for a more detailed evaluation. We found that the drugs dose-dependently activate both receptors in β-arrestin recruitment assays, stimulate ERK1/2 phosphorylation in HEK293 cells overexpressing each receptor, and that their effects on CXCR4 could be inhibited with AMD3100. Both α₁-AR antagonists induced significant chemical shift changes in the ¹H-¹³C-heteronuclear single quantum correlation spectrum of CXCR4 and ACKR3 in membranes, suggesting receptor binding. Furthermore, prazosin and cyclazosin induced internalization of endogenous CXCR4/ACKR3 in human vascular smooth muscle cells (hVSMC). While these drugs did not in induce chemotaxis in hVSMC, they inhibited CXCL12-induced chemotaxis with high efficacy and potency (IC₅₀: prazosin—4.5 nM, cyclazosin 11.6 pM). Our findings reveal unexpected pharmacological properties of prazosin, cyclazosin, and likely other α₁-AR antagonists. The results of the present study imply that prazosin and cyclazosin are biased or partial CXCR4/ACKR3 agonists, which function as potent CXCL12 antagonists. Our findings could provide a mechanistic basis for previously observed anti-cancer properties of α₁-AR antagonists and support the concept that prazosin could be re-purposed for the treatment of disease processes in which CXCR4 and ACKR3 are thought to play significant pathophysiological roles, such as cancer metastases or various autoimmune pathologies.

Human UDP-Glucuronosyltransferase 2B4 and 2B7 Are Responsible for Naftopidil Glucuronidation in Vitro

Naftopidil (NAF) is widely used for the treatment of benign prostatic hyperplasia and prevention of prostate cancer in elderly men. These patients receive a combination of drugs, which involves high risk for drug–drug interaction. NAF exhibits superior efficacy but must be administered at a much higher dosage than other therapeutic drugs. We previously showed that extensive glucuronidation of NAF enantiomers caused poor bioavailability. However, the metabolic pathway and mechanism of action of NAF enantiomer remain to be elucidated. The present study was performed to identify the human UDP-glucuronosyltransferases (UGTs) responsible for the glucuronidation of NAF enantiomers and to investigate the potential inhibition of UGT activity by NAF. The major metabolic sites examined were liver and kidney, which were compared with intestine. Screening of 12 recombinant UGTs showed that UGT2B7 primarily contributed to the metabolism of both enantiomers. Moreover, enzyme kinetics for R(+)-NAF, UGT2B7 (mean K_m, 21 μM; mean V_max, 1043 pmol/min/mg) showed significantly higher activity than observed for UGT2B4 and UGT1A9. UGT2B4 (mean K_m, 55 μM; mean V_max, 1976 pmol/min/mg) and UGT2B7 (mean K_m, 38 μM; mean V_max, 1331 pmol/min/mg) showed significantly higher catalysis of glucuronidation of S(-)-NAF than UGT1A9. In human liver microsomes, R(+)-NAF and S(-)-NAF also inhibited UGT1A9: mean K_i values for R(+)-NAF and S(-)-NAF were 10.0 μM and 11.5 μM, respectively. These data indicate that UGT2B7 was the principal enzyme mediating glucuronidation of R(+)-NAF and S(-)-NAF. UGT2B4 plays the key role in the stereoselective metabolism of NAF enantiomers. R(+)-NAF and S(-)-NAF may inhibit UGT1A9. Understanding the metabolism of NAF enantiomers, especially their interactions with metabolic enzymes, will help to elucidate potential drug–drug interactions and to optimize the administration of this medicine.

Additive naftopidil treatment synergizes docetaxel-induced apoptosis in human prostate cancer cells

PURPOSE

Docetaxel (DTX) is a standard chemotherapeutic drug for castration-resistant prostate cancer (CRPC), although adverse events are common. To overcome this problem, researchers have evaluated the efficacy of DTX treatment in combination with other drugs. Naftopidil is a tubulin-binding drug with fewer adverse events, implying the usefulness of this drug in clinical applications when combined with DTX. Here, we investigated the efficacy of additive naftopidil treatment in combination with DTX on prostate cancer (PCa) cells.

METHODS

The effects of combination treatment with DTX plus naftopidil were analyzed using two animal models of LNCaP cells plus PrSC xenografts (sub-renal capsule grafting) and PC-3 xenografts (intratibial injection).

RESULTS

Combination treatment with DTX plus naftopidil significantly inhibited cell growth in LNCaP cells compared with DTX alone. Analysis of the cooperativity index (CI) showed that combination treatment exhibited additive effects on DTX-induced growth inhibition in LNCaP cells. In contrast, combination treatment showed more than an additive (synergistic) effect on DTX-induced apoptosis in LNCaP and PC-3 cells. In LNCaP cells plus PrSC xenografts, combination treatment showed synergistic effects on DTX-induced apoptosis. The synergistic effects of naftopidil on DTX-induced apoptosis were also observed in PC-3 xenografts.

CONCLUSIONS

Our results demonstrated that additive naftopidil treatment in combination with DTX increased the efficacy of DTX for the treatment of LNCaP and PC-3 tumors in vivo. Thus, additive naftopidil treatment showed a synergistic effect on DTX-induced apoptosis in PCa cells in vitro and in vivo, suggesting that this treatment approach may yield improved clinical benefits compared with DTX alone.

Sympathetic nervous system promotes hepatocarcinogenesis by modulating inflammation through activation of alpha1-adrenergic receptors of Kupffer cells

The sympathetic nervous system (SNS) is known to play a significant role in tumor initiation and metastasis. Hepatocellular carcinoma (HCC) frequently occurs in cirrhotic livers after chronic inflammation, and the SNS is hyperactive in advanced liver cirrhosis. However, it remains unclear whether the SNS promotes hepatocarcinogenesis by modulating chronic liver inflammation. In this study, a retrospective pathological analysis and quantification of sympathetic nerve fiber densities (tyrosine hydroxylase, TH⁺) in HCC patients, and diethylnitrosamine (DEN)-induced hepatocarcinogenesis in rats were performed. Our data showed that high density of sympathetic nerve fibers and α1-adrenergic receptors (ARs) of Kupffer cells (KCs) were associated with a poor prognosis of HCC. Sympathetic denervation or blocking of α1-ARs decreased DEN-induced HCC incidence and tumor development. In addition, synergistic effects of interleukin-6 (IL-6) and transforming growth factor-beta (TGF-β) in hepatocarcinogenesis were observed. The suppression of the SNS reduced IL-6 and TGF-β expression, which suppressed hepatocarcinogenesis, and KCs play a key role in this process. After the ablation of KCs, IL-6 and TGF-β expression and the development of HCC were inhibited. This study demonstrates that sympathetic innervation is crucial for hepatocarcinogenesis and that the SNS promotes hepatocarcinogenesis by activating α1-ARs of KCs to boost the activation of KCs and to maintain the inflammatory microenvironment. These results indicate that sympathetic denervation or α1-ARs blockage may represent novel treatment approaches for HCC.

Pharmaceutical evaluation of naftopidil enantiomers: Rat functional assays in vitro and estrogen/androgen induced rat benign prostatic hyperplasia model in vivo

Naftopidil (NAF) is a α_1D/1A adrenoceptor selective drug used for the treatment of both benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS). However, NAF is used as a racemate in clinic. To compare the differences and similarities among two enantiomers and racemate, pharmacological activities were evaluated through rat functional assays in vitro and estrogen/androgen (E/T) induced rat BPH model in vivo. NAF and the two enantiomers showed similar blocking activity on α₁ receptor. S-NAF exhibited more α_1D/1A adrenoceptor subtype selectivity than R-NAF and the racemate. The selectivity ratios pA₂ (α_1D)/pA₂ (α_1B) and pA₂ (α_1A)/pA₂ (α_1B) were 40.7- and 16.2-fold, respectively. NAF and its enantiomers effectively prevented the development of rat prostatic hyperplasia via suppressing the increase of the prostatic wet weight, visually. The quantitative analysis of the relative acinus volume, relative stroma volume, relative epithelial volume, epithelial height and expression of proliferating cell nuclear antigen (PCNA) and α-smooth muscle actin (α-SMA) were carried out. S-NAF showed an advantage on the effect of inhibiting prostate wet weight and stroma volume over R-NAF and racemate NAF (P<0.05). Nevertheless, no other significant difference was observed between these two enantiomers. In conclusion, both R-NAF and S-NAF not only relax prostate muscle but also inhibit the prostate growth, thus relieve BPH.

The Role of α1-Adrenoceptor Antagonists in the Treatment of Prostate and Other Cancers

This review evaluates the role of α-adrenoceptor antagonists as a potential treatment of prostate cancer (PCa). Cochrane, Google Scholar and Pubmed were accessed to retrieve sixty-two articles for analysis. In vitro studies demonstrate that doxazosin, prazosin and terazosin (quinazoline α-antagonists) induce apoptosis, decrease cell growth, and proliferation in PC-3, LNCaP and DU-145 cell lines. Similarly, the piperazine based naftopidil induced cell cycle arrest and death in LNCaP-E9 cell lines. In contrast, sulphonamide based tamsulosin did not exhibit these effects. In vivo data was consistent with in vitro findings as the quinazoline based α-antagonists prevented angiogenesis and decreased tumour mass in mice models of PCa. Mechanistically the cytotoxic and antitumor effects of the α-antagonists appear largely independent of α 1-blockade. The proposed targets include: VEGF, EGFR, HER2/Neu, caspase 8/3, topoisomerase 1 and other mitochondrial apoptotic inducing factors. These cytotoxic effects could not be evaluated in human studies as prospective trial data is lacking. However, retrospective studies show a decreased incidence of PCa in males exposed to α-antagonists. As human data evaluating the use of α-antagonists as treatments are lacking; well designed, prospective clinical trials are needed to conclusively demonstrate the anticancer properties of quinazoline based α-antagonists in PCa and other cancers.

Enantiospecific determination of naftopidil by RRLC-MS/MS reveals stereoselective pharmacokinetics and tissue distributions in rats

Naftopidil (NAF) is used as a racemate to treat benign prostatic hyperplasia (BPH) and to prevent prostate cancer. However, racemic NAF has low bioavailability; therefore, it is commonly administered at higher clinical dosages compared to other therapeutic BPH drugs. Differences in interactions between individual enantiomers and biological macromolecules may result in variations in pharmacokinetics and dispositions. This study aimed to investigate the pharmacokinetics, bioavailability and tissue distributions of NAF enantiomers in rats after intragastric administration of the individual enantiomers. A rapid and sensitive liquid chromatography coupled with triple-quadrupole mass spectrometric method (RRLC-MS/MS) was developed and validated for determination of NAF enantiomers in rat plasma, tissues, urine and feces. After intragastric administration, S(-)-NAF in plasma [maximum concentration (C(max)) = 186.4 ng/mL, area under the curve from 0 h to 24h (AUC(0-24 h)) = 877.9 ng h/mL] was significantly higher than that of R(+)-NAF (C(max) = 133.2 ng/mL, AUC(0-24 h) = 602.1 ng h/mL). Moreover, S(-)-NAF bioavailability was twice that of R(+)-NAF. R(+)-NAF distributions in the prostate, liver, and kidney were significantly higher than S(-)-NAF distributions (R/S ratios of 3.16, 1.33, and 2.90, respectively). These data reveal the stereoselective pharmacokinetic profiles of the two enantiomers in rats.

Novel naftopidil-related derivatives and their biological effects as alpha1-adrenoceptors antagonists and antiproliferative agents

Eleven novel naftopidil-related compounds that contain amide and indole groups were designed and synthesized. The biological effects of these compounds on three α1-adrenoceptor subtypes and cancerous human prostate cell lines (PC-3, DU-145, and LNCaP) were determined. Compounds 2, 3, 5, 11, and 12 exhibited an α1-adrenoceptor antagonistic activity, whereas compounds 9, 10, and 12 displayed moderate antiproliferative activities. Compound 3 exhibited a significant α(1D/1A) blocking activity in isolated rat tissues (97.7- and 64.6-fold selective for α(1D) and α(1A) compared with α(1B)) but not a relevant cytotoxic activity. Compound 12 demonstrated a potent and selective α(1D/1A) antagonistic activity (47.9- and 19.1-fold for α(1D) and α(1A) compared with α1B) and a potent antiproliferative activity in PC-3 cells (IC50 = 15.70 μM). Further testing confirmed that compound 12 inhibited the growth of PC-3 cells by inducing apoptosis and G0/G1 cell cycle arrest, which was mediated by α1-adrenoceptor. Therefore, compound 12 is a potential multipotent agent that can act as an effective α1-adrenoceptor subtype antagonist for treating benign prostatic hyperplasia and a preventive medication against human prostate cancer.