Autophagy deactivation is associated with severe prostatic inflammation in patients with lower urinary tract symptoms and benign prostatic hyperplasia

The role of autophagy in prostate cancer and prostatic diseases: a new therapeutic strategy

BACKGROUND

Autophagy is a well-conserved catabolic process that plays a key role in cell homeostasis. In the prostate, defective autophagy has been implicated in the genesis and progression of several pathological conditions.

AIM

The present review explored the autophagy pathway in prostate-related dysfunctions, focusing on prostate cancer (PCa), benign prostatic hyperplasia (BPH) and prostatitis.

RESULTS

Impaired autophagy activity has been shown in animal models of BPH and prostatitis. Moreover, autophagy activation by specific and non-specific drugs improved both conditions in pre-clinical studies. Conversely, the efficacy of autophagy inducers in PCa remains controversial, depending on intrinsic PCa characteristics and stage of progression. Intriguingly, autophagy inhibitors have shown beneficial effects in PCa suppression or even to overcome chemotherapy resistance. However, there are still open questions regarding the upstream mechanisms by which autophagy is deregulated in the prostate and the exact role of autophagy in PCa. The lack of specificity and increased toxicity associated with the currently autophagy inhibitors limits its use clinically, reflecting in reduced number of clinical data.

CONCLUSION

New therapeutic strategies to treat prostatic diseases involving new autophagy modulators, combination therapy and new drug formulations should be explored. Understanding the autophagy signaling in each prostatic disease is crucial to determine the best pharmacological approach.

Tissue immunoexpression of IL-6 and IL-18 in aging men with BPH and MetS and their relationship with lipid parameters and gut microbiota-derived short chain fatty acids

Recent studies indicate that inflammation is one of the causes of the development of benign prostatic hyperplasia (BPH). Inflammation may result from past infections, metabolic disorders, but also from the state of functioning of the intestinal microbiota. The aim of the study was to assess whether the diagnostic lipid parameters for metabolic syndrome and short-chain fatty acids (SCFAs) are related to the immunoexpression of interleukins in prostate tissue with benign hyperplasia. The study involved 103 men with BPH, who were divided into two groups depending on the presence of MetS. We analysed tissue immunoexpression of two proinflammatory interleukins: IL-6, which is known to be involved in the development of BPH, and IL-18, which has not been analysed so far. The results of our study indicate that men with BPH + MetS in the stroma of the prostate have a significantly higher overall percentage of IL-6+ cells compared to men without MetS (p = 0.034). The analysis of IL-18 immunoexpression in prostate tissue indicated that in men with BPH + MetS, the glandular part of the prostate had a significantly higher percentage of cells with strong IL-18 expression (p = 0.040). We also noticed a relationship between tissue expression of IL-6 and IL-18 and lipid parameters (TG and HDL). We conclude that lipid disorders occurring in men with BPH increase inflammation in the prostate gland. Moreover, it has also been demonstrated for the first time that, indirectly, through SCFAs, the gut microbiota can act to prevent or create an inflammatory microenvironment in the prostate gland.

Does benign prostate hyperplasia histopathological variation impact disease-specific clinical outcomes after transurethral resection?

The impact of histopathological variants in stromal and glandular tissue on clinical outcomes following transurethral resection of prostate (TURP) is unexplored. We sought to evaluate the relationship between histopathological variations in TURP specimen and postoperative clinical outcomes. We performed a retrospective analysis of men undergoing initial TURP at our institution from 2017 to 2019. All pathology slides were re-reviewed by one specialized genitourinary pathologist who was blinded to all clinical data. Types of BPH were defined as: glandular-predominant (gland:stroma ratio >50%), mixed (gland:stroma ratio 25%-50%), and stromal-predominant (gland:stromal ratio <25%). Primary clinical outcomes were ∆ post-void residual and ∆ American Urological Society Symptom Score (AUASS) at 3, 6, and 12 months post-operatively. We also evaluated for a temporal relationship between time since surgery and ∆AUASS amongst different histopathological subgroups. One hundred and five patients were included in the final analysis. 61/105 (58.1%) had glandular-predominant histopathology, 21/105 (20%) had stromal-predominant histopathology, and 23/105 (21.9%) were classified as mixed histopathology. On univariate and multivariate analysis, histopathological subtype was not a significant predictor of any of the clinical post-operative endpoints of interest at any time points. Disease-specific outcomes after TURP appear to be consistent across these different histopathologic subtypes.

Rauwolfia vomitoria extract suppresses benign prostatic hyperplasia by inducing autophagic apoptosis through endoplasmic reticulum stress

Background

The current drug treatments for benign prostatic hyperplasia (BPH) have negative side effects. Therefore, it is important to find effective alternative therapies with significantly fewer side effects. Our previous study revealed that Rauwolfia vomitoria (RWF) root bark extract reversed BPH development in a rat model. However, the molecular mechanism of its inhibitory effects on BPH remains largely unknown.

Methods

BPH-1 and WPMY-1 cell lines derived from BPH epithelial and prostatic stromal compartments were selected to investigate how RWF extract inhibits BPH in vitro by MTT and flow cytometry assays. Microarray, quantitative real-time PCR, immunoblotting, and GFP-LC3 immunofluorescence assays were performed to evaluate the effects of RWF extract on endoplasmic reticulum stress (ER stress) and autophagic apoptosis pathways in two cell lines. A human BPH ex vivo explant assay was also employed for validation.

Results

RWF extract treatment decreased cell viability and induced apoptotic cell death in both BPH-1 and WPMY-1 cells in a concentration-dependent manner with the increase of pro-apoptotic PCDC4 protein. RWF extract induced autophagy by enhancing the levels of autophagic genes (ULK2 and SQSTM1/p62) and the LC3II:LC3I ratio, with the increase of GFP-LC3 puncta. Moreover, RWF extract activated PERK- and ATF6-associated ER stress pathways by inducing the transcriptional levels of EIF2AK3/PERK, DDIT3/CHOP and ATF6, accompanied by the reduction of BiP protein level, but not its mRNA level. Another ER stress pathway was not induced by RWF extract, as manifested by the lack of XBP1 splicing. Pharmacological inhibition of autophagy by 3-methyladenine abrogated apoptosis but not ER stress; while inhibition of ER stress by 4-phenylbutyrate alleviated the induction of autophagy and apoptosis. In addition, pretreatments with either 3-methyladenine or 4-phenylbutyrate suppressed RWF extract-induced cytotoxicity. Notably, the inductions of PERK- and ATF6-related stress pathways and autophagic apoptosis were confirmed in a human BPH ex vivo explant.

Conclusions

Our data have demonstrated that RWF extract significantly suppressed the viabilities of BPH epithelial cells and BPH myofibroblasts by inducing apoptosis via upregulating ER stress and autophagy. These data indicate that RWF extract is a potential novel alternative therapeutic approach for BPH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03610-4.

IL-6 Signaling Link between Inflammatory Tumor Microenvironment and Prostatic Tumorigenesis

Benign prostatic hyperplasia and prostate cancer are tumoral pathologies characterized by the overexpression of inflammatory processes. The exploration of tumor microenvironment and understanding the sequential events that take place in the stromal area of the prostate could help for an early management of these pathologies. This way, it is feasible the hypothesis that normalizing the stromal environment would help to suppress or even to reverse tumor fenotype. A number of immunological and genetic factors, endocrine dysfunctions, metabolic disorders, infectious foci, nutritional deficiencies, and chemical irritants could be involved in prostate tumor development by maintaining inflammation, affecting local microcirculation, and promoting oxidative stress. Inflammatory processes activate hyperproliferative programs that ensure fibromuscular growth of the prostate and a number of extracellular changes. Acute and chronic inflammations cause accumulation of immunocompetent cells in affected prostate tissue (T cells, macrophages, mastocytes, dendritic cells, neutrophils, eosinophils, monocytes). Prostate epithelial and stromal cells, peri-prostatic fat cells, prostatic microvascular endothelial cells, and inflammatory cells produce cytokines, generating a local inflammatory environment. Interleukin-6 (IL-6) proved to be involved in the prostate tumor pathogenesis. IL-6 ability to induce pro- and anti-inflammatory responses by three mechanisms of signal transduction (classical signaling, transsignaling, cluster signaling), to interact with a diversity of target cells, to induce endocrine effects in an autocrine/paracrine manner, and the identification of an IL-6 endogenous antagonist that blocks the transmission of IL-6 mediated intracellular signals could justify current theories on the protective effects of this cytokine or by alleviating inflammatory reactions or by exacerbating tissue damage. This analysis presents recent data about the role of the inflammatory process as a determining factor in the development of benign and malign prostate tumors. The presented findings could bring improvements in the field of physiopathology, diagnosis, and treatment in patients with prostate tumors. Modulation of the expression and activity of interleukin-6 could be a mean of preventing or improving these pathologies.

The Etiology and Pathophysiology Genesis of Benign Prostatic Hyperplasia and Prostate Cancer: A New Perspective

Background: The etiology of benign prostatic hyperplasia and prostate cancer are unknown, with ageing being the greatness risk factor. Methods: This new perspective evaluates the available interdisciplinary evidence regarding prostate ageing in terms of the cell biology of regulation and homeostasis, which could explain the timeline of evolutionary cancer biology as degenerative, inflammatory and neoplasm progressions in these multifactorial and heterogeneous prostatic diseases. Results: This prostate ageing degeneration hypothesis encompasses the testosterone-vascular-inflamm-ageing triad, along with the cell biology regulation of amyloidosis and autophagy within an evolutionary tumorigenesis microenvironment. Conclusions: An understanding of these biological processes of prostate ageing can provide potential strategies for early prevention and could contribute to maintaining quality of life for the ageing individual along with substantial medical cost savings.

Qianliexin capsule exerts anti-inflammatory activity in chronic non-bacterial prostatitis and benign prostatic hyperplasia via NF-κB and inflammasome

Qianliexin capsule (QLX) is a standardized traditional Chinese herbal preparation that has long been used to treat chronic non‐bacterial prostatitis (CNP) and benign prostatic hyperplasia (BPH). This study investigated the anti‐inflammatory activity of QLX in improving lower urinary tract symptoms (LUTS) associated with CNP and BPH. Rat models of CNP and BPH were induced by oestradiol or testosterone (hormonal imbalance) or chemical inflammation (carrageenan). QLX significantly relieved LUTS in CNP and BPH rat model by reducing prostate enlargement, epithelial thickness, pain response time, urine volume and bleeding time, and by improving prostatic blood flow. The expression of the pro‐inflammatory cytokines interleukin (IL)‐1β and tumour necrosis factor (TNF)‐α, the pro‐inflammatory transcription factor nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB), and inflammasome components (NLRP3, caspase‐1 and ASC) in CNP and BPH tissues was reduced by QLX addition. QLX treatment was followed by reduced cellular malondialdehyde and increased superoxide dismutase, catalase and glutathione peroxidase activity, consistent with antioxidant activity. Increases in Beclin‐1 expression and the LC3II/I ratio following QLX treatment indicated that autophagy had been induced. QLX relieved LUTS in CNP and BPH rat models by inhibiting inflammation. The underlying mechanisms included inhibition of inflammasome activation, NF‐κB activation, oxidant stress and autophagy.

Impairment of autophagy may represent the molecular mechanism behind the relationship between obesity and inflammation in patients with BPH and LUTS

BACKGROUND

Aim of this study was to evaluate the roles of inflammation and autophagy in obese patients with benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS).

METHODS

We analyzed 150 surgical specimens from patients underwent transurethral resection of the prostate (TURP) for LUTS/BPH (Median age 70.3±8.1 years, median BMI 25.7±4.0 kg/m² and median PSA 6.0±5.4 ng/mL). All surgical specimens were investigated for the presence inflammatory infiltrates, according to the standardized classification of chronic prostatitis of the National Institute of Health. The inflammatory score (IS Score) was calculated. High IS score was defined as ≥7. Each sample was stained for anti-LC3B (cell signaling) and for anti-P62/SQSTM1 (MBL) according to manufacturer's suggestions and scored as follow: 0 (no dots); 1 (detectable dots in 5-25% of cells); 2 (readily detectable dots in 25-75% of cells); 3 (dots in >75% of cells). High percentage of p62 or LC3B was defined as >25%, whereas low percentage of p62 or LC3B was defined as <25% of cells with dots.

RESULTS

Overall 74/150 (49.3%) patients were overweight or obese (BMI >25 kg/m²). Obese patients presented a higher inflammatory score. Obese/overweight patients presented a lower percentage of LC3B (58/74; 78.4%) and higher of p62 (49/74; 66.2%) compared to those of normal weight, which it means a deactivated autophagy (P<0.05). At multivariate analysis LC3B (OR=0.22; CI: 0.069-0.70; P=0.01) percentage and BMI (OR=1.118; CI: 1.001-1.250; P=0.04) were independent risk factors of prostatic inflammation (IS≥7).

CONCLUSIONS

Here we confirm the association between obesity and prostatic inflammatory infiltrates and present the first evidence of autophagy deregulation in obese patients with LUTS/BPH. Further studies should better investigate this relationship and provide new possible therapeutic targets.

Measurement of autophagy flux in benign prostatic hyperplasia in vitro

Background

Recent studies have suggested a novel therapeutic strategy for treatment of benign prostatic hyperplasia (BPH) via modulation of autophagy. However, it is not clear whether autophagy induction or inhibition can render better therapeutic efficacy for BPH treatment because autophagy activation in BPH tissue is not precisely known and still contradictory. The purpose of this study was to examine the levels of autophagy in BPH tissue cells.

Methods

We have analyzed and compared autophagic flux which is defined as a measure of autophagic degradation activity in two human prostate epithelial cell lines, RWPE-1 (normal prostate) and BPH-1 (BPH) using LC3-II turnover assay, to clarify the levels of autophagy in BPH.

Results

The in vitro autophagy flux assays showed that autophagy flux was significantly decreased in BPH-1 cell lines compared with RWPE-1 cells under all three conditions of using the original (~62%), the exchanged (~46%), and the same media (Hank's balanced salt solution (HBSS), ~40%), and these results were similar to those seen in the prostate of testosterone-induced BPH rats (~50%) (P < 0.05).

Conclusion

It is suggested that defective autophagy, which is decreased autophagy flux in the prostate gland, may be implicated in BPH, and activating autophagy flux of the prostate with BPH may be used as a potential therapeutic target for treating and alleviating BPH disease.

Rapamycin Alleviates Hormone Imbalance-Induced Chronic Nonbacterial Inflammation in Rat Prostate Through Activating Autophagy via the mTOR/ULK1/ATG13 Signaling Pathway

Chronic prostatitis (CP) is a clinically common disease with high morbidity. It affects the patients' quality of life (QoL) as well as physical and mental health seriously due to the recurring symptoms of lower urinary tract and genitalia. As the opinions about the etiology of CP are still not uniform, it is very difficult to be treated or even cured. Autophagy is a highly conserved physiological function which is widely found in eukaryotic cells. In general, cells maintain a certain level of autophagy under physiological conditions, and the basal level of autophagy can be regulated by a variety of autophagy-related genes under stress such as hunger, infection, trauma, and other circumstances. Therefore, the main purpose of this study is to investigate the role of autophagy in chronic nonbacterial prostatitis (CNP, also called CP). In this paper, we established the CNP model via hypodermic injection of 17β-estradiol and subsequently abdominal rapamycin (a common autophagy inducer) treatment based on castrated rats. Then, the expression of nuclear factor-κB (NF-κB), interleukin-1β (IL-1β), and autophagy-related markers as well as autophagosome formation in prostate tissues, peripheral blood mononuclear cells (PBMCs), and serum of rats were evaluated respectively. In addition to some histological changes in the prostate tissues, we found the levels of NF-κB and IL-1β were significantly increased in the model group, along with significantly suppressed autophagy, whereas rapamycin could reverse these effects which involved in the mTOR/ULK1/ATG13 signaling pathway. In conclusion, our results suggested that rapamycin could ameliorate hormone imbalance-induced CNP by activating autophagy.

Water‑soluble nano‑pearl powder promotes MC3T3‑E1 cell differentiation by enhancing autophagy via the MEK/ERK signaling pathway

Nacre (mother of pearl) is a bioactive material capable of facilitating osteoblast proliferation and differentiation; however, further investigation into the mechanism underlying the effects of nacre on the stimulation of bone differentiation is required. The present study aimed to elucidate the effects of water‑soluble nano‑pearl powder (WSNNP) on osteoblast differentiation and to examine the underlying mechanisms. A MTT assay revealed that WSNNP (10, 25 and 50 µg/ml) may stimulate the viability of preosteoblastic MC3T3‑E1 cells and 50 µg/ml WSNNP exhibited the maximum stimulatory effect. Furthermore, WSNNP significantly enhanced the protein expression levels of differentiation markers, including collagen I, runt‑related transcription factor 2 (RUNX2), secreted phosphoprotein1 (SPP1) and alkaline phosphatase (ALP) in a dose‑dependent manner, which indicated that WSNNP may promote osteoblast differentiation. Subsequently, whether autophagy serves a role in WSNNP‑mediated differentiation of osteoblasts was investigated via western blotting and immunofluorescence. The results of the present study demonstrated that WSNNP treatment significantly evoked the expression of autophagy markers, including microtubule‑associated light chain 3 (LC3)II/I, Beclin1 and autophagy‑related 7 (ATG7), whereas the autophagy inhibitor 3‑methyladenine significantly inhibited WSNNP‑induced osteoblast differentiation. Furthermore, the role of WSNNP on the potential signaling pathways that activate autophagy was investigated. The present study reported that WSNNP may significantly upregulate the mitogen‑activated protein kinase kinase (MEK)/extracellular signal‑regulated kinase (ERK) signaling pathway. Treatment with the MEK inhibitor U0126 significantly inhibited the protein expression levels of WSNNP‑induced differentiation markers, including collagen I, RUNX2, SPP1 and ALP, and autophagy markers, including LC3II/I, Beclin1 and ATG7. Therefore, the findings of the present study suggested that WSNNP may contribute to osteoblast differentiation by enhancing autophagy via the MEK/ERK signaling pathway, thus suggesting a novel direction for optimizing the biological materials in bone implants.