Interleukin-6 induces VEGF secretion from prostate cancer cells in a manner independent of androgen receptor activation

Interactions and communications in the prostate tumour microenvironment: evolving towards effective cancer therapy

Prostate cancer is one of the most common malignancies in men. The tumour microenvironment (TME) has a critical role in the initiation, progression, and metastasis of prostate cancer. TME contains various cell types, including cancer-associated fibroblasts (CAFs), endothelial cells, immune cells such as macrophages, lymphocytes B and T, natural killer (NK) cells, and other proteins such as extracellular matrix (ECM) components. The interactions and communications between these cells within the TME are crucial for the growth and response of various solid tumours, such as prostate cancer to different anticancer modalities. In this review article, we exemplify the various mechanisms by which the TME influences prostate cancer progression. The roles of different cells, cytokines, chemokines, and growth factors in modulating the immune response and prostate tumour growth will be discussed. The impact of these cells and factors and other ECM components on tumour cell invasion and metastasis will also be discussed. We explain how these interactions in TME can affect the response of prostate cancer to therapy. We also highlight the importance of understanding these interactions to develop novel therapeutic approaches for prostate cancer.

Application of Original Prostate Cancer Progression Model Interacting with Fibroblasts in Preclinical Research

Prostate cancer (PCa) is a heterogeneous disease that exhibits androgen sensitivity and responsiveness to androgen deprivation therapy (ADT). However, ADT induces only temporary remission, and the majority of PCa cases eventually progress to castration-resistant PCa (CRPC). During the development and progression of CRPC, androgen sensitivity and androgen receptor (AR) dependency in PCa cells are often deceased or lost due to ADT or spontaneously arising AR variants even before starting ADT. To prevent CRPC, a clinical PCa model derived from an AR-positive cancer cell line with weak or no androgen sensitivity is required. The human prostate LNCaP cell line is a good model for PCa because of its androgen sensitivity and AR dependency in terms of cell growth and gene expression. Notably, LNCaP cells are heterogeneous cells comprising different clones with natural variations in androgen sensitivity and AR dependency resulting from spontaneously occurring changes. In our group, to obtain androgen-insensitive or weakly sensitive clones spontaneously derived from parental LNCaP cells, we performed a limiting dilution of parental LNCaP cells and obtained several sublines with varying levels of androgen sensitivity and AR dependency. In addition, we established an androgen-insensitive subline from parental LNCaP cells by continuous passage under hormone-depleted conditions. This article provides a unique perspective on our original PCa progression model interacting with fibroblasts and its application in preclinical research.

Evidence of the Link between Stroma Remodeling and Prostate Cancer Prognosis

Prostate cancer (PCa), the most commonly diagnosed cancer in men worldwide, is particularly challenging for oncologists when a precise prognosis needs to be established. Indeed, the entire clinical management in PCa has important drawbacks, generating an intense debate concerning the possibility to individuate molecular biomarkers able to avoid overtreatment in patients with pathological indolent cancers. To date, the paradigmatic change in the view of cancer pathogenesis prompts to look for prognostic biomarkers not only in cancer epithelial cells but also in the tumor microenvironment. PCa ecology has been defined with increasing details in the last few years, and a number of promising key markers associated with the reactive stroma are now available. Here, we provide an updated description of the most biologically significant and cited prognosis-oriented microenvironment biomarkers derived from the main reactive processes during PCa pathogenesis: tissue adaptations, inflammatory response and metabolic reprogramming. Proposed biomarkers include factors involved in stromal cell differentiation, cancer-normal cell crosstalk, angiogenesis, extracellular matrix remodeling and energy metabolism.

Myocardial Oedema as a Consequence of Viral Infection and Persistence-A Narrative Review with Focus on COVID-19 and Post COVID Sequelae

Microvascular integrity is a critical factor in myocardial fluid homeostasis. The subtle equilibrium between capillary filtration and lymphatic fluid removal is disturbed during pathological processes leading to inflammation, but also in hypoxia or due to alterations in vascular perfusion and coagulability. The degradation of the glycocalyx as the main component of the endothelial filtration barrier as well as pericyte disintegration results in the accumulation of interstitial and intracellular water. Moreover, lymphatic dysfunction evokes an increase in metabolic waste products, cytokines and inflammatory cells in the interstitial space contributing to myocardial oedema formation. This leads to myocardial stiffness and impaired contractility, eventually resulting in cardiomyocyte apoptosis, myocardial remodelling and fibrosis. The following article reviews pathophysiological inflammatory processes leading to myocardial oedema including myocarditis, ischaemia-reperfusion injury and viral infections with a special focus on the pathomechanisms evoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition, clinical implications including potential long-term effects due to viral persistence (long COVID), as well as treatment options, are discussed.

TRPM2-L Participates in the Interleukin-6 Pathway to Enhance Tumor Growth in Prostate Cancer by Hypoxia-Inducible Factor-1α

Interleukin-6 (IL-6) can promote cell proliferation in prostate cancer (PCa). Full-length transient receptor potential melastatin 2 (TRPM2-L) is highly expressed in PCa. However, the association between IL-6 and TRPM2-L in PCa is unclear. Here, human PCa cell lines, PC-3 and DU-145, were treated with 10 μg/mL tocilizumab, an IL-6 receptor (IL-6R) inhibitor, and the TRPM2-L protein expression in cells was significantly decreased. Cells were stably transfected with TRPM2 short-interfering RNA (siRNA) and cell survival clearly declined. Recombinant IL-6 treatment weakened the effects of TRPM2-siRNA on cell survival. TRPM2-L binds directly to IL-6R in PC-3 and DU-145 cells. The protein expression of hypoxia-inducible factor-1α was suppressed by reduction with TRPM2-L in PC-3 and DU-145 cells. Human umbilical vein endothelial cells (HUVECs) were indirectly cocultured with PCa cells, and the invasion and angiogenic activity of HUVECs were enhanced after coculture with PCa cells. However, TRPM2-L reduction in PCa cells significantly decreased the invasion and angiogenic activity of HUVECs compared to the control coculture. In vivo, xenograft tumors were induced using PC-3 cells. Tocilizumab treatment or TRPM2-L reduction clearly suppressed tumor growth. Meanwhile, the injection of mouse recombinant IL-6 weakened the antitumor effects of TRPM2-L reduction. These data demonstrate that the IL-6/TRPM2-L axis in PCa tumor growth is important, and interference of the IL-6/TRPM2-L axis may be a novel approach for PCa therapy.

Identification and validation of cancer-associated fibroblast-related subtypes and the prognosis model of biochemical recurrence in prostate cancer based on single-cell and bulk RNA sequencing

BACKGROUND

Cancer-associated fibroblasts (CAFs) are an essential component of the tumor immune microenvironment that are involved in extracellular matrix (ECM) remodeling. We aim to investigate the characteristics of CAFs in prostate cancer and develop a biochemical recurrence (BCR)-related CAF signature for predicting the prognosis of PCa patients.

METHODS

The bulk RNA-seq and relevant clinical information were obtained from the TCGA and GEO databases, respectively. The infiltration scores of CAFs in prostate cancer patients were calculated using the MCP counter and EPIC algorithms. The single-cell RNA sequencing (scRNA-seq) was downloaded from the GEO database. Subsequently, univariate Cox regression analysis was employed to identify prognostic genes associated with CAFs. We identified two subtypes (C1 and C2) of prostate cancer that were associated with CAFs via non-negative matrix factorization (NMF) clustering. In addition, the BCR-related CAF signatures were constructed using Lasso regression analysis. Finally, a nomogram model was established based on the risk score and clinical characteristics of the patients.

RESULTS

Initially, we found that patients with high CAF infiltration scores had shorter biochemical recurrence-free survival (BCRFS) times. Subsequently, CAFs in four pairs of tumors and paracancerous tissues were identified. We discovered 253 significantly differentially expressed genes, of which 13 had prognostic significance. Using NMF clustering, we divided PCa patients into C1 and C2 subgroups, with the C1 subgroup having a worse prognosis and substantially enriched cell cycle, homologous recombination, and mismatch repair pathways. Furthermore, a BCR-related CAFs signature was established. Multivariate COX regression analysis confirmed that the BCR-related CAFs signature was an independent prognostic factor for BCR in PCa. In addition, the nomogram was based on the clinical characteristics and risk scores of the patient and demonstrated high accuracy and reliability for predicting BCR. Lastly, our findings indicate that the risk score may be a useful tool for predicting PCa patients' sensitivity to immunotherapy and drug treatment.

CONCLUSION

NMF clustering based on CAF-related genes revealed distinct TME immune characteristics between groups. The BCR-related CAF signature accurately predicted prognosis and immunotherapy response in prostate cancer patients, offering a promising new approach to cancer treatment.

New insights and options into the mechanisms and effects of combined targeted therapy and immunotherapy in prostate cancer

Chronic inflammation is believed to drive prostate carcinogenesis by producing reactive oxygen species or reactive nitrogen species to induce DNA damage. This effect might subsequently cause epigenetic and genomic alterations, leading to malignant transformation. Although established therapeutic advances have extended overall survival, tumors in patients with advanced prostate cancer are prone to metastasis, transformation into metastatic castration-resistant prostate cancer, and therapeutic resistance. The tumor microenvironment (TME) of prostate cancer is involved in carcinogenesis, invasion and drug resistance. A plethora of preclinical studies have focused on immune-based therapies. Understanding the intricate TME system in prostate cancer may hold much promise for developing novel therapies, designing combinational therapeutic strategies, and further overcoming resistance to established treatments to improve the lives of prostate cancer patients. In this review, we discuss nonimmune components and various immune cells within the TME and their putative roles during prostate cancer initiation, progression, and metastasis. We also outline the updated fundamental research focusing on therapeutic advances of targeted therapy as well as combinational options for prostate cancer.

Establishment of cancer-associated fibroblasts-related subtypes and prognostic index for prostate cancer through single-cell and bulk RNA transcriptome

Current evidence indicate that cancer-associated fibroblasts (CAFs) play an important role in prostate cancer (PCa) development and progression. In this study, we identified CAF-related molecular subtypes and prognostic index for PCa patients undergoing radical prostatectomy through integrating single-cell and bulk RNA sequencing data. We completed analyses using software R 3.6.3 and its suitable packages. Through single-cell and bulk RNA sequencing analysis, NDRG2, TSPAN1, PTN, APOE, OR51E2, P4HB, STEAP1 and ABCC4 were used to construct molecular subtypes and CAF-related gene prognostic index (CRGPI). These genes could clearly divide the PCa patients into two subtypes in TCGA database and the BCR risk of subtype 1 was 13.27 times higher than that of subtype 2 with statistical significance. Similar results were observed in MSKCC2010 and GSE46602 cohorts. In addtion, the molucular subtypes were the independent risk factor of PCa patients. We orchestrated CRGPI based on the above genes and divided 430 PCa patients in TCGA database into high- and low- risk groups according to the median value of this score. We found that high-risk group had significant higher risk of BCR than low-risk group (HR: 5.45). For functional analysis, protein secretion was highly enriched in subtype 2 while snare interactions in vesicular transport was highly enriched in subtype 1. In terms of tumor heterogeneity and stemness, subtype 1 showd higher levels of TMB than subtype 2. In addition, subtype 1 had significant higher activated dendritic cell score than subtype 2. Based on eight CAF-related genes, we developed two prognostic subtypes and constructed a gene prognostic index, which could predict the prognosis of PCa patients very well.

Cancer-Associated Fibroblast: Role in Prostate Cancer Progression to Metastatic Disease and Therapeutic Resistance

Prostate cancer (PCa) is one of the most common cancers in European males. Although therapeutic approaches have changed in recent years, and several new drugs have been approved by the Food and Drug Administration (FDA), androgen deprivation therapy (ADT) remains the standard of care. Currently, PCa represents a clinical and economic burden due to the development of resistance to ADT, paving the way to cancer progression, metastasis, and to long-term side effects induced by ADT and radio-chemotherapeutic regimens. In light of this, a growing number of studies are focusing on the tumor microenvironment (TME) because of its role in supporting tumor growth. Cancer-associated fibroblasts (CAFs) have a central function in the TME because they communicate with prostate cancer cells, altering their metabolism and sensitivity to drugs; hence, targeted therapy against the TME, and, in particular, CAFs, could represent an alternative therapeutic approach to defeat therapy resistance in PCa. In this review, we focus on different CAF origins, subsets, and functions to highlight their potential in future therapeutic strategies for prostate cancer.

Prostate fibroblasts enhance androgen receptor splice variant 7 expression in prostate cancer cells

BACKGROUND

Androgen receptor splice variant (AR-V) expression has been associated with prostate cancer (PCa) progression to castration-resistant PCa during androgen deprivation therapy, which reduces androgen production and inhibits androgen action in PCa cells. However, the mechanisms whereby aberrant AR-V expression is increased in PCa are still largely unknown. Fibroblasts in tumor stroma influence PCa initiation and aggressiveness, and which may play a crucial role in eliciting genetic changes during malignant transformation in human prostate epithelium. Here, our aim was to determine whether prostate fibroblasts in tumor stroma induce aberrant AR-V7 expression in PCa cells under low androgen concentration.

METHODS

We performed in vitro experiments using androgen-sensitive, AR-positive PCa cell lines (LNCaP and 22Rv1 cells), commercially available prostate stromal cells (PrSC), and primary cultured prostate fibroblasts (pcPrF) from PCa specimens collected from biopsies of patients with advanced PCa. PCa cells were cocultured with each of the three fibroblast lines (PrSC, pcPrF-M37, and pcPrF-M48).

RESULTS

The proliferation under low androgen concentration of LNCaP and 22Rv1 cells cocultured with PrSC, pcPrF-M37, or pcPrF-M48 was significantly increased compared to that of PCa cells cultured alone. Androgen receptor-full length (AR-FL) protein expression was increased in LNCaP and 22Rv1 cells cocultured with PrSC, pcPrF-M37, or pcPrF-M48. AR-V7 protein expression was increased in 22Rv1 cells cocultured with PrSC, pcPrF-M37, or pcPrF-M48. Under low androgen concentration, AR-V7 protein expression was slightly detected in LNCaP cells cocultured with PrSC or pcPrF-M37. Cytokine array analysis revealed that monocyte chemotactic protein-1 (MCP-1) and interleukin-8 (IL-8) levels in the conditioned medium of 22Rv1 cells cocultured with PrSC, pcPrF-M37, or pcPrF-M48 were increased under low androgen concentration. High IL-8 concentration (30 ng/ml) resulted in significantly increased protein expression of AR-FL, AR-V7, and phospho-NF-κB p65 in 22Rv1 cells. In contrast, IL-8 antibody (1 µg/ml) decreased AR-V7 protein expression in 22Rv1 cells cocultured with PrSC, pcPrF-M37, or pcPrF-M48.

CONCLUSIONS

pcPrF from PCa specimens increase the expression of aberrant AR-V7 in PCa cells. IL-8 may be a target for preventing the expression of aberrant AR-Vs in PCa.

Cancer-Associated Fibroblast Heterogeneity, Activation and Function: Implications for Prostate Cancer

The continuous remodeling of the tumor microenvironment (TME) during prostate tumorigenesis is emerging as a critical event that facilitates cancer growth, progression and drug-resistance. Recent advances have identified extensive communication networks that enable tumor-stroma cross-talk, and emphasized the functional importance of diverse, heterogeneous stromal fibroblast populations during malignant growth. Cancer-associated fibroblasts (CAFs) are a vital component of the TME, which mediate key oncogenic events including angiogenesis, immunosuppression, metastatic progression and therapeutic resistance, thus presenting an attractive therapeutic target. Nevertheless, how fibroblast heterogeneity, recruitment, cell-of-origin and differential functions contribute to prostate cancer remains to be fully delineated. Developing our molecular understanding of these processes is fundamental to developing new therapies and biomarkers that can ultimately improve clinical outcomes. In this review, we explore the current challenges surrounding fibroblast identification, discuss new mechanistic insights into fibroblast functions during normal prostate tissue homeostasis and tumorigenesis, and illustrate the diverse nature of fibroblast recruitment and CAF generation. We also highlight the promise of CAF-targeted therapies for the treatment of prostate cancer.

Prostate Cancer Tumor Stroma: Responsibility in Tumor Biology, Diagnosis and Treatment

Simple Summary

The crosstalk between prostate stroma and its epithelium is essential to tissue homeostasis. Likewise, reciprocal signaling between tumor cells and the stromal compartment is required in tumor progression to facilitate or stimulate key processes such as cell proliferation and invasion. The aim of the present work was to review the current state of knowledge on the significance of tumor stroma in the genesis, progression and therapeutic response of prostate carcinoma. Additionally, we addressed the future therapeutic opportunities.

Abstract

Prostate cancer (PCa) is a common cancer among males globally, and its occurrence is growing worldwide. Clinical decisions about the combination of therapies are becoming highly relevant. However, this is a heterogeneous disease, ranging widely in prognosis. Therefore, new approaches are needed based on tumor biology, from which further prognostic assessments can be established and complementary strategies can be identified. The knowledge of both the morphological structure and functional biology of the PCa stroma compartment can provide new diagnostic, prognostic or therapeutic possibilities. In the present review, we analyzed the aspects related to the tumor stromal component (both acellular and cellular) in PCa, their influence on tumor behavior and the therapeutic response and their consideration as a new therapeutic target.

Potential Mechanisms of Pyrrosiae Folium in Treating Prostate Cancer Based on Network Pharmacology and Molecular Docking

Objective The network pharmacology approach and molecular docking were employed to explore the mechanism of Pyrrosiae Folium(PF) against prostate cancer (PCa). Methods The active compounds and their corresponding putative targets of PF were identified by the Traditional Chinese Medicine Systems Pharmacology (TCMSP), the gene names of the targets were obtained from the UniProt database. The collection of genes associated with PCa were obtained from GeneCards and DisGeNET database. We merged the drug targets and disease targets by online software, Draw Venn Diagram. The resulting gene list was imported into R software (v3.6.3) for GO and KEGG function enrichment analysis. The STRING database was utilized for protein-protein interaction (PPI) network construction. The cytoHubba plugin of Cytoscape was used to identify core genes. Further, molecular docking analysis of the hub targets were carried out using AutoDock Vina software (v1.5.6). Results A total of 6 active components were screened by PF, with 167 corresponding putative targets, 1395 related targets for PCa, and 113 targets for drugs and diseases. The "drug-component-disease-target" network was constructed by Cytoscape software and the target genes mainly involved in the complex treating effects associated with response to oxidative stress, cytokine activity, pathways in cancer, prostate cancer pathway and TNF signaling pathway. Core genes in the PPI network were TNF, JUN, IL6, IL1B, CXCL8, RELA, CCL2, TP53, IL10 and FOS. The molecular docking results reveal the better binding affinity of 6 active components to the core targets. Conclusion The results of this study indicated that PF may be have a certain anti-PCa effect by regulating related target genes, affecting Pathways in cancer, TNF signaling pathway, Hepatitis B signaling pathway.

Aggressive variants of prostate cancer: underlying mechanisms of neuroendocrine transdifferentiation

Prostate cancer is a hormone-driven disease and its tumor cell growth highly relies on increased androgen receptor (AR) signaling. Therefore, targeted therapy directed against androgen synthesis or AR activation is broadly used and continually improved. However, a subset of patients eventually progresses to castration-resistant disease. To date, various mechanisms of resistance have been identified including the development of AR-independent aggressive variant prostate cancer based on neuroendocrine transdifferentiation (NED). Here, we review the highly complex processes contributing to NED. Genetic, epigenetic, transcriptional aberrations and posttranscriptional modifications are highlighted and the potential interplay of the different factors is discussed. Background Aggressive variant prostate cancer (AVPC) with traits of neuroendocrine differentiation emerges in a rising number of patients in recent years. Among others, advanced therapies targeting the androgen receptor axis have been considered causative for this development. Cell growth of AVPC often occurs completely independent of the androgen receptor signal transduction pathway and cells have mostly lost the typical cellular features of prostate adenocarcinoma. This complicates both diagnosis and treatment of this very aggressive disease. We believe that a deeper understanding of the complex molecular pathological mechanisms contributing to transdifferentiation will help to improve diagnostic procedures and develop effective treatment strategies. Indeed, in recent years, many scientists have made important contributions to unravel possible causes and mechanisms in the context of neuroendocrine transdifferentiation. However, the complexity of the diverse molecular pathways has not been captured completely, yet. This narrative review comprehensively highlights the individual steps of neuroendocrine transdifferentiation and makes an important contribution in bringing together the results found so far.

Prostate Microbiota and Prostate Cancer: A New Trend in Treatment

Although the incidence and mortality of prostate cancer have gradually begun to decline in the past few years, it is still one of the leading causes of death from malignant tumors in the world. The occurrence and development of prostate cancer are affected by race, family history, microenvironment, and other factors. In recent decades, more and more studies have confirmed that prostate microflora in the tumor microenvironment may play an important role in the occurrence, development, and prognosis of prostate cancer. Microorganisms or their metabolites may affect the occurrence and metastasis of cancer cells or regulate anti-cancer immune surveillance. In addition, the use of tumor microenvironment bacteria in interventional targeting therapy of tumors also shows a unique advantage. In this review, we introduce the pathway of microbiota into prostate cancer, focusing on the mechanism of microorganisms in tumorigenesis and development, as well as the prospect and significance of microorganisms as tumor biomarkers and tumor prevention and treatment.

Heterogeneous induction of an invasive phenotype in prostate cancer cells by coculturing with patient-derived fibroblasts

Prostate cancer (PCa) cells frequently invade the surrounding stroma, leading to heterogeneous formation of structural atypia. The surrounding stroma contains multiple functionally diverse populations of fibroblasts that trigger numerous changes in PCa cells including motility. Thus, we hypothesized that direct or indirect contact of PCa cells with fibroblasts determines an invasive phenotype in PCa cells. We investigated the effects of 10 different patient-derived fibroblast lines on the three-dimensional (3D) morphogenesis of PCa cells growing on a viscous substrate in vitro. When grown alone, all 10 patient-derived fibroblast lines clumped on the viscous substrate, whereas the human androgen-sensitive PCa cell line LNCaP did not. Cocultures of LNCaP cells with seven of the patient-derived fibroblast lines (PrSC, pcPrF-M5, pcPrF-M7, pcPrF-M23, pcPrF-M24, pcPrF-M28, and pcPrF-M31) formed a thick fibroblast layer that resembled human prostate stromal structures. In contrast, cocultures of LNCaP cells with the remaining three fibroblast lines (NPF-M13, pcPrF-M10, and pcPrF-M26) did not form a thick fibroblast layer. Of the seven fibroblast lines that caused thick layer formation, four patient-derived fibroblast lines (PrSC, pcPrF-M5, pcPrF-M28, and pcPrF-M31) induced an invasive phenotype in LNCaP cells with a cord-like infiltrating growth pattern, whereas the other three fibroblast lines (pcPrF-M7, pcPrF-M23, and pcPrF-M24) induced no or a very weak invasive phenotype. Using cell culture inserts, none of the four patient-derived fibroblast lines that induced an invasive phenotype (PrSC, pcPrF-M5, pcPrF-M28, and pcPrF-M31) affected CDH1 mRNA expression in LNCaP cells; yet, two patient-derived fibroblast lines (pcPrF-M5 and pcPrF-M28) increased CDH2 mRNA expression in LNCaP cells, whereas the other two fibroblast lines (PrSC and pcPrF-M31) did not. These results suggest that the existence of multiple functionally diverse populations of fibroblasts in PCa tissue may be responsible for the diversity in PCa cell invasion, leading to heterogeneous formation of structural atypia.

The Role of Cancer-Associated Fibroblasts in Prostate Cancer Tumorigenesis

Tumors strongly depend on their surrounding tumor microenvironment (TME) for growth and progression, since stromal elements are required to generate the optimal conditions for cancer cell proliferation, invasion, and possibly metastasis. Prostate cancer (PCa), though easily curable during primary stages, represents a clinical challenge in advanced stages because of the acquisition of resistance to anti-cancer treatments, especially androgen-deprivation therapies (ADT), which possibly lead to uncurable metastases such as those affecting the bone. An increasing number of studies is giving evidence that prostate TME components, especially cancer-associated fibroblasts (CAFs), which are the most abundant cell type, play a causal role in PCa since the very early disease stages, influencing therapy resistance and metastatic progression. This is highlighted by the prognostic value of the analysis of stromal markers, which may predict disease recurrence and metastasis. However, further investigations on the molecular mechanisms of tumor-stroma interactions are still needed to develop novel therapeutic approaches targeting stromal components. In this review, we report the current knowledge of the characteristics and functions of the stroma in prostate tumorigenesis, including relevant discussion of normal prostate homeostasis, chronic inflammatory conditions, pre-neoplastic lesions, and primary and metastatic tumors. Specifically, we focus on the role of CAFs, to point out their prognostic and therapeutic potential in PCa.

Association between immunosuppressive cytokines and PSA progression in biochemically recurrent prostate cancer treated with intermittent hormonal therapy

BACKGROUND

Immunosuppressive cytokines have the potential to promote prostate cancer progression. Assessing their longitudinal changes may implicate mechanisms of progression, treatment resistance, and suggest new therapeutic targets.

METHODS

Thirty-seven men with biochemically recurrent (BCR) prostate cancer who received 6 months of androgen deprivation therapy (ADT) and were monitored until the time to prostate-specific antigen progression (TTPP) were identified from a completed phase III trial (NCT00020085). Serum samples were archived at baseline, 3 months after ADT, and at TTPP. Cytokine concentrations were quantified using a 36-parameter electrochemiluminescence assay. The Wilcoxon signed-rank sum test was used to compare observations between time points. Kaplan-Meier analysis was used to calculate TTPP dichotomized by cytokine values above or below the median. Pearson's rank correlation coefficient was used to compare continuous variables.

RESULTS

Median TTPP was 399 days (range, 114-1641). Median prostate-specific antigen (PSA) at baseline and progression were 8.5 and 5.3 ng/mL, respectively. Twenty-three patients (62%) achieved undetectable PSA with ADT. Castrate levels of testosterone (<50 ng/dL) after 3 months of ADT occurred in 35 patients (95%). TNF-α (P = .002), IL-23 (P = .002), and CXCL10 (P = .001) significantly increased from baseline to post ADT. Certain cytokines correlated longitudinally: TNF-α correlated with IL-23 (r = .72; P < .001) and IL-8 (r = .59; P < .001) from baseline to post ADT and to PSA progression. Neutrophil-to-lymphocyte ratio correlated with IL-27 (r = .57; P < .001) and MIP-3α (r = .56; P < .001). Patients with a detectable PSA after ADT had elevated levels of IL-6 (P = .049) and IL-8 (P = .013) at PSA progression as compared with those with an undetectable PSA. There was a trend toward shorter TTPP in patients with TNF-α levels above the median (P = .042).

CONCLUSIONS

Several innate cytokines were associated with biochemically recurrent prostate cancer.

Molecular Links Between Angiogenesis and Neuroendocrine Phenotypes in Prostate Cancer Progression

As a common therapy for prostate cancer, androgen deprivation therapy (ADT) is effective for the majority of patients. However, prolonged ADT promotes drug resistance and progression to an aggressive variant with reduced androgen receptor signaling, so called neuroendocrine prostate cancer (NEPC). Until present, NEPC is still poorly understood, and lethal with no effective treatments. Elevated expression of neuroendocrine related markers and increased angiogenesis are two prominent phenotypes of NEPC, and both of them are positively associated with cancers progression. However, direct molecular links between the two phenotypes in NEPC and their mechanisms remain largely unclear. Their elucidation should substantially expand our knowledge in NEPC. This knowledge, in turn, would facilitate the development of effective NEPC treatments. We recently showed that a single critical pathway regulates both ADT-enhanced angiogenesis and elevated expression of neuroendocrine markers. This pathway consists of CREB1, EZH2, and TSP1. Here, we seek new insights to identify molecules common to pathways promoting angiogenesis and neuroendocrine phenotypes in prostate cancer. To this end, our focus is to summarize the literature on proteins reported to regulate both neuroendocrine marker expression and angiogenesis as potential molecular links. These proteins, often described in separate biological contexts or diseases, include AURKA and AURKB, CHGA, CREB1, EZH2, FOXA2, GRK3, HIF1, IL-6, MYCN, ONECUT2, p53, RET, and RB1. We also present the current efforts in prostate cancer or other diseases to target some of these proteins, which warrants testing for NEPC, given the urgent unmet need in treating this aggressive variant of prostate cancer.

Revisiting signal transducer and activator of transcription 3 (STAT3) as an anticancer target and its inhibitor discovery: Where are we and where should we go?

As a transcription factor, STAT3 protein transduces extracellular signals to the nucleus and then activates transcription of target genes. STAT3 has been well validated as an attractive anticancer target due to its important roles in cancer initiation and progression. Identification of specific and potent STAT3 inhibitors has attracted much attention, while there has been no STAT3 targeted drug approved for clinical application. In this review, we will briefly introduce STAT3 protein and review its role in multiple aspects of cancer, and systematically summarize the recent advances in discovery of STAT3 inhibitors, especially the ones discovered in the past five years. In the last part of the review, we will discuss the possible new strategies to overcome the difficulties of developing potent and specific STAT3 inhibitors and hope to shed light on future drug design and inhibitor optimization.

Loss of Fibroblast-Dependent Androgen Receptor Activation in Prostate Cancer Cells is Involved in the Mechanism of Acquired Resistance to Castration

Loss of androgen receptor (AR) dependency in prostate cancer (PCa) cells is associated with progression to castration-resistant prostate cancer (CRPC). The tumor stroma is enriched in fibroblasts that secrete AR-activating factors. To investigate the roles of fibroblasts in AR activation under androgen deprivation, we used three sublines of androgen-sensitive LNCaP cells (E9 and F10 cells: low androgen sensitivity; and AIDL cells: androgen insensitivity) and original fibroblasts derived from patients with PCa. We performed in vivo experiments using three sublines of LNCaP cells and original fibroblasts to form homotypic tumors. The volume of tumors derived from E9 cells plus fibroblasts was reduced following androgen deprivation therapy (ADT), whereas that of F10 or AIDL cells plus fibroblasts was increased even after ADT. In tumors derived from E9 cells plus fibroblasts, serum prostate-specific antigen (PSA) decreased rapidly after ADT, but was still detectable. In contrast, serum PSA was increased even in F10 cells inoculated alone. In indirect cocultures with fibroblasts, PSA production was increased in E9 cells. Epidermal growth factor treatment stimulated Akt and p44/42 mitogen-activated protein kinase phosphorylation in E9 cells. Notably, AR splice variant 7 was detected in F10 cells. Overall, we found that fibroblast-secreted AR-activating factors modulated AR signaling in E9 cells after ADT and loss of fibroblast-dependent AR activation in F10 cells may be responsible for CRPC progression.

VEGFR2 survival and mitotic signaling depends on joint activation of associated C3ar1/C5ar1 and IL-6R-gp130

Purified vascular endothelial cell (EC) growth factor receptor-2 (VEGFR2) auto-phosphorylates upon VEGF-A occupation in vitro, arguing that VEGR2 confers its mitotic and viability signaling in and of itself. Herein, we show that, in ECs, VEGFR2 function requires concurrent C3a/C5a receptor (C3ar1/C5ar1) and IL-6 receptor (IL-6R)-gp130 co-signaling. C3ar1/C5ar1 or IL-6R blockade totally abolished VEGFR2 auto-phosphorylation, downstream Src, ERK, AKT, mTOR and STAT3 activation, and EC cell cycle entry. VEGF-A augmented production of C3a/C5a/IL-6 and their receptors via a two-step p-Tyk2/p-STAT3 process. Co-immunoprecipitation analyses, confocal microscopy, ligand pulldown and bioluminescence resonance energy transfer assays all indicated that the four receptors are physically interactive. Angiogenesis in murine day 5 retinas and in adult tissues was accelerated when C3ar1/C5ar1 signaling was potentiated, but repressed when it was disabled. Thus, C3ar1/C5ar1 and IL-6R-gp130 joint activation is needed to enable physiological VEGFR2 function.

Pirfenidone, an Anti-Fibrotic Drug, Suppresses the Growth of Human Prostate Cancer Cells by Inducing G₁ Cell Cycle Arrest

Pirfenidone (PFD) is an anti-fibrotic drug used to treat idiopathic pulmonary fibrosis by inducing G₁ cell cycle arrest in fibroblasts. We hypothesize that PFD can induce G₁ cell cycle arrest in different types of cells, including cancer cells. To investigate the effects of PFD treatment on the growth of human prostate cancer (PCa) cells, we used an androgen-sensitive human PCa cell line (LNCaP) and its sublines (androgen-low-sensitive E9 and F10 cells and androgen-insensitive AIDL cells), as well as an androgen-insensitive human PCa cell line (PC-3). PFD treatment suppressed the growth of all PCa cells. Transforming growth factor β1 secretion was significantly increased in PFD-treated PCa cells. In both LNCaP and PC-3 cells, PFD treatment increased the population of cells in the G₀/G₁ phase, which was accompanied by a decrease in the S/G₂ cell population. CDK2 protein expression was clearly decreased in PFD-treated LNCaP and PC-3 cells, whereas p21 protein expression was increased in only PFD-treated LNCaP cells. In conclusion, PFD may serve as a novel therapeutic drug that induces G₁ cell cycle arrest in human PCa cells independently of androgen sensitivity. Thus, in the tumor microenvironment, PFD might target not only fibroblasts, but also heterogeneous PCa cells of varying androgen-sensitivity levels.