The Role of Cancer-Associated Fibroblasts in Prostate Cancer Tumorigenesis

Mapping the tumor stress network reveals dynamic shifts in the stromal oxidative stress response

The tumor microenvironment (TME) presents cells with challenges such as variable pH, hypoxia, and free radicals, triggering stress responses that affect cancer progression. In this study, we examine the stress response landscape in four carcinomas-breast, pancreas, ovary, and prostate-across five pathways: heat shock, oxidative stress, hypoxia, DNA damage, and unfolded protein stress. Using a combination of experimental and computational methods, we create an atlas of stress responses across various types of carcinomas. We find that stress responses vary within the TME and are especially active near cancer cells. Focusing on the non-immune stroma we find, across tumor types, that NRF2 and the oxidative stress response are distinctly activated in immune-regulatory cancer-associated fibroblasts and in a unique subset of cancer-associated pericytes. Our study thus provides an interactome of stress responses in cancer, offering ways to intersect survival pathways within the tumor, and advance cancer therapy.

Prognostic and therapeutic potential of senescent stromal fibroblasts in prostate cancer

The stromal component of the tumour microenvironment in primary and metastatic prostate cancer can influence and promote disease progression. Within the prostatic stroma, fibroblasts are one of the most prevalent cell types associated with precancerous and cancerous lesions; they have a vital role in the structural composition, organization and integrity of the extracellular matrix. Fibroblasts within the tumour microenvironment can undergo cellular senescence, which is a stable arrest of cell growth and a phenomenon that is emerging as a recognized hallmark of cancer. Supporting the idea that cellular senescence has a pro-tumorigenic role, a subset of senescent cells exhibits a senescence-associated secretory phenotype (SASP), which, along with increased inflammation, can promote prostate cancer cell growth and survival. These cellular characteristics make targeting senescent cells and/or modulating SASP attractive as a potential preventive or therapeutic option for prostate cancer.

Cancer-Associated Fibroblast Induces Acinar-to-Ductal Cell Transdifferentiation and Pancreatic Cancer Initiation Via LAMA5/ITGA4 Axis

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDAC) is characterized by desmoplastic stroma surrounding most tumors. Activated stromal fibroblasts, namely cancer-associated fibroblasts (CAFs), play a major role in PDAC progression. We analyzed whether CAFs influence acinar cells and impact PDAC initiation, that is, acinar-to-ductal metaplasia (ADM). ADM connection with PDAC pathophysiology is indicated, but not yet established. We hypothesized that CAF secretome might play a significant role in ADM in PDAC initiation.

METHODS

Mouse and human acinar cell organoids, acinar cells cocultured with CAFs and exposed to CAF-conditioned media, acinar cell explants, and CAF cocultures were examined by means of quantitative reverse transcription polymerase chain reaction, RNA sequencing, immunoblotting, and confocal microscopy. Data from liquid chromatography with tandem mass spectrometry analysis of CAF-conditioned medium and RNA sequencing data of acinar cells post-conditioned medium exposure were integrated using bioinformatics tools to identify the molecular mechanism for CAF-induced ADM. Using confocal microscopy, immunoblotting, and quantitative reverse transcription polymerase chain reaction analysis, we validated the depletion of a key signaling axis in the cell line, acinar explant coculture, and mouse cancer-associated fibroblasts (mCAFs).

RESULTS

A close association of acino-ductal markers (Ulex europaeus agglutinin 1, amylase, cytokeratin-19) and mCAFs (α-smooth muscle actin) in LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1Cre (KPC) and LSL-KrasG12D/+; Pdx1Cre (KC) autochthonous progression tumor tissue was observed. Caerulein treatment-induced mCAFs increased cytokeratin-19 and decreased amylase in wild-type and KC pancreas. Likewise, acinar-mCAF cocultures revealed the induction of ductal transdifferentiation in cell line, acinar-organoid, and explant coculture formats in WT and KC mice pancreas. Proteomic and transcriptomic data integration revealed a novel laminin α5/integrinα4/stat3 axis responsible for CAF-mediated acinar-to-ductal cell transdifferentiation.

CONCLUSIONS

Results collectively suggest the first evidence for CAF-influenced acino-ductal phenotypic switchover, thus highlighting the tumor microenvironment role in pancreatic carcinogenesis inception.

Single-cell analysis revealing the metabolic landscape of prostate cancer

Tumor metabolic reprogramming is a hallmark of cancer development, and targeting metabolic vulnerabilities has been proven to be an effective approach for castration-resistant prostate cancer (CRPC) treatment. Nevertheless, treatment failure inevitably occurs, largely due to cellular heterogeneity, which cannot be deciphered by traditional bulk sequencing techniques. By employing computational pipelines for single-cell RNA sequencing, we demonstrated that epithelial cells within the prostate are more metabolically active and plastic than stromal cells. Moreover, we identified that neuroendocrine (NE) cells tend to have high metabolic rates, which might explain the high demand for nutrients and energy exhibited by neuroendocrine prostate cancer (NEPC), one of the most lethal variants of prostate cancer (PCa). Additionally, we demonstrated through computational and experimental approaches that variation in mitochondrial activity is the greatest contributor to metabolic heterogeneity among both tumor cells and nontumor cells. These results establish a detailed metabolic landscape of PCa, highlight a potential mechanism of disease progression, and emphasize the importance of future studies on tumor heterogeneity and the tumor microenvironment from a metabolic perspective.

Identification of functional and diverse circulating cancer-associated fibroblasts in metastatic castration-naïve prostate cancer patients

In prostate cancer (PCa), cancer-associated fibroblasts (CAFs) promote tumor progression, drug resistance, and metastasis. Although circulating tumor cells are studied as prognostic and diagnostic markers, little is known about other circulating cells and their association with PCa metastasis. Here, we explored the presence of circulating CAFs (cCAFs) in metastatic castration-naïve prostate cancer (mCNPC) patients. cCAFs were stained with fibroblast activation protein (FAP), epithelial cell adhesion molecule (EpCAM), and receptor-type tyrosine-protein phosphatase C (CD45), then FAP+EpCAM- cCAFs were enumerated and sorted using fluorescence-activated cell sorting. FAP+EpCAM- cCAFs ranged from 60 to 776 (389 mean ± 229 SD) per 2 × 108 mononuclear cells, whereas, in healthy donors, FAP+ EpCAM- cCAFs ranged from 0 to 71 (28 mean ± 22 SD). The mCNPC-derived cCAFs showed positivity for vimentin and intracellular collagen-I. They were viable and functional after sorting, as confirmed by single-cell collagen-I secretion after 48 h of culturing. Two cCAF subpopulations, FAP+CD45- and FAP+CD45+, were identified, both expressing collagen-I and vimentin, but with distinctly different morphologies. Collectively, this study demonstrates the presence of functional and viable circulating CAFs in mCNPC patients, suggesting the role of these cells in prostate cancer.

Molecular imaging reveals the heterogeneous progression of tumor cells and tumor stroma: a practice of FDG PET and FAPI PET in diagnosing PSMA-negative bone metastases of progressive prostate cancer

Tumors are often with complex and heterogeneous biological processes, such as glycometabolism and fibrosis, which are the main biochemical pathways that determine therapeutic effects. Specifically, this study aims to assess the diagnosing performance of 18F-FDG and 68Ga-FAPI-04 PET for different stages of progressive bone metastases with PSMA-negative pathology. Bone metastatic mouse model of prostate cancer was constructed via intra-bone injection of PSMA-negative prostate cancer PC3 cells. Cellular uptakes of 18F-FDG and 68Ga-FAPI-04 were separately performed on PC3, NIH-3T3 (FAP-positive) and a mixture. 68Ga-PSMA-11, 18F-FDG and 68Ga-FAPI-04 PET/CT imaging were performed at 2, 4 weeks after tumor cell transplantation. Furthermore, PSMA and FAP expression in bone metastases were assessed by immunohistochemistry, and then compared with the imageological findings. On the cellular level, the independent tracer uptake on the basis of glycometabolism and fibrosis was observed. For animal imaging, 68Ga-PSMA-11 imaging showed weak or absent tracer uptake in PSMA-negative bone metastatic lesions. In contrast, 68Ga-FAPI-04 PET of bone metastases had a higher uptake and tumor-to-muscle (T/M) ratio than 18F-FDG PET that was relative steady during the observation, but T/M ratio of fibrosis gradually decreased with increasing tumor growth, which ranged from 5.11 ± 1.26 at 2 weeks to 3.54 ± 0.23 at 4 weeks, revealing the delayed formation of tumor stroma in rapid proliferation. In addition, PET imaging results were corroborated by immunohistochemical assessment. In conclusion, molecular imaging approach revealed the heterogeneous progression of tumor cells and tumor stroma of bone metastasis of prostate cancer, and further confirming the necessity of multi-molecular imaging in cancer imaging.

Downregulation of S100A11 promotes T cell infiltration by regulating cancer-associated fibroblasts in prostate cancer

OBJECTIVE

This study aims at revealing the relationship between S100A11 and cancer-associated fibroblasts (CAFs) in prostate cancer and improving T cell infiltration into solid tumors.

METHODS

H&E, IHC and Sirius red staining were used to detect the stroma content in prostate cancer tissues. Stable S100A11 knockdown cell lines DU 145, 22Rv1, RM-1 and NOR-10 were established by lentivirus transfection. Co-culture system of RM-1 and CAFs was established. CCK-8, wound healing and transwell were proceeded to determine proliferation, migration and invasion of prostate cancer cells. Stably knocked-down RM-1 and CAFs were co-injected into C57BL/6 mice to detect the role of S100A11 in vivo. CAFs, CD4+ T cell and CD8+ T cell in these tumors were assessed by IF. T cell profile was analyzed by flow cytometry.

RESULTS

A significant amount of stroma exists in prostate cancer tissues. Downregulation of S100A11 inhibits proliferation, migration and invasion of human prostate cancer cells in vitro, and suppresses the expression of cancer-associated fibroblasts (CAFs) in vivo. Knockdown of S100A11 enhances the inhibitory effect of Erdafitinib on CAFs in both the co-culture system and in vivo. The combined knockdown of S100A11 in tumor cells and CAFs shows a superior therapeutic effect compared to the individual knockdown in tumor cells alone. Knockdown of S100A11, both in RM-1 and CAFs, combined with Erdafitinib treatment reduces tumorigenicity by suppressing the content of CAFs and increasing the infiltration of CD4+ T cell and effective CD8+ T cell in tumor.

CONCLUSION

Downregulation of S100A11 plays a crucial role in enhancing the therapeutic response to Erdafitinib and reversing immunosuppressive tumor microenvironment.

Stromal-derived MAOB promotes prostate cancer growth and progression

Prostate cancer (PC) develops in a microenvironment where the stromal cells modulate adjacent tumor growth and progression. Here, we demonstrated elevated levels of monoamine oxidase B (MAOB), a mitochondrial enzyme that degrades biogenic and dietary monoamines, in human PC stroma, which was associated with poor clinical outcomes of PC patients. Knockdown or overexpression of MAOB in human prostate stromal fibroblasts indicated that MAOB promotes cocultured PC cell proliferation, migration, and invasion and co-inoculated prostate tumor growth in mice. Mechanistically, MAOB induces a reactive stroma with activated marker expression, increased extracellular matrix remodeling, and acquisition of a protumorigenic phenotype through enhanced production of reactive oxygen species. Moreover, MAOB transcriptionally activates CXCL12 through Twist1 synergizing with TGFβ1-dependent Smads in prostate stroma, which stimulates tumor-expressed CXCR4-Src/JNK signaling in a paracrine manner. Pharmacological inhibition of stromal MAOB restricted PC xenograft growth in mice. Collectively, these findings characterize the contribution of MAOB to PC and suggest MAOB as a potential stroma-based therapeutic target.

Uncovering Minimal Pathways in Melanoma Initiation

Cutaneous melanomas are clinically and histologically heterogeneous. Most display activating mutations in Braf or Nras and complete loss of function of one or more tumor suppressor genes. Mouse models that replicate such mutations produce fast-growing, pigmented tumors. However, mice that combine Braf activation with only heterozygous loss of Pten also produce tumors and, as we show here, in an Albino background this occurs even with Braf activation alone. Such tumors arise rarely, grow slowly, and express low levels of pigmentation genes. The timing of their appearance was consistent with a single step stochastic event, but no evidence could be found that it required de novo mutation, suggesting instead the involvement of an epigenetic transition. Single-cell transcriptomic analysis revealed such tumors to be heterogeneous, including a minor cell type we term LNM ( L ow-pigment, N eural- and extracellular M atrix-signature) that displays gene expression resembling "neural crest"-like cell subsets detected in the fast-growing tumors of more heavily-mutated mice, as well as in human biopsy and xenograft samples. We provide evidence that LNM cells pre-exist in normal skin, are expanded by Braf activation, can transition into malignant cells, and persist with malignant cells through multiple rounds of transplantation. We discuss the possibility that LNM cells not only serve as a pre-malignant state in the production of some melanomas, but also as an important intermediate in the development of drug resistance.

PRADclass: Hybrid Gleason Grade-Informed Computational Strategy Identifies Consensus Biomarker Features Predictive of Aggressive Prostate Adenocarcinoma

BACKGROUND

Prostate adenocarcinoma (PRAD) is a common cancer diagnosis among men globally, yet large gaps in our knowledge persist with respect to the molecular bases of its progression and aggression. It is mostly indolent and slow-growing, but aggressive prostate cancers need to be recognized early for optimising treatment, with a view to reducing mortality.

METHODS

Based on TCGA transcriptomic data pertaining to PRAD and the associated clinical metadata, we determined the sample Gleason grade, and used it to execute: (i) Gleason-grade wise linear modeling, followed by five contrasts against controls and ten contrasts between grades; and (ii) Gleason-grade wise network modeling via weighted gene correlation network analysis (WGCNA). Candidate biomarkers were obtained from the above analysis and the consensus found. The consensus biomarkers were used as the feature space to train ML models for classifying a sample as benign, indolent or aggressive.

RESULTS

The statistical modeling yielded 77 Gleason grade-salient genes while the WGCNA algorithm yielded 1003 trait-specific key genes in grade-wise significant modules. Consensus analysis of the two approaches identified two genes in Grade-1 (SLC43A1 and PHGR1), 26 genes in Grade-4 (including LOC100128675, PPP1R3C, NECAB1, UBXN10, SERPINA5, CLU, RASL12, DGKG, FHL1, NCAM1, and CEND1), and seven genes in Grade-5 (CBX2, DPYS, FAM72B, SHCBP1, TMEM132A, TPX2, UBE2C). A RandomForest model trained and optimized on these 35 biomarkers for the ternary classification problem yielded a balanced accuracy ∼ 86% on external validation.

CONCLUSIONS

The consensus of multiple parallel computational strategies has unmasked candidate Gleason grade-specific biomarkers. PRADclass, a validated AI model featurizing these biomarkers achieved good performance, and could be trialed to predict the differentiation of prostate cancers. PRADclass is available for academic use at: https://apalania.shinyapps.io/pradclass (online) and https://github.com/apalania/pradclass (command-line interface).

Fibroblast activation protein: Pivoting cancer/chemotherapeutic insight towards heart failure

An important mechanism for cancer progression is degradation of the extracellular matrix (ECM) which is accompanied by the emergence and proliferation of an activated fibroblast, termed the cancer associated fibroblast (CAF). More specifically, an enzyme pathway identified to be amplified with local cancer progression and proliferation of the CAF, is fibroblast activation protein (FAP). The development and progression of heart failure (HF) irrespective of the etiology is associated with left ventricular (LV) remodeling and changes in ECM structure and function. As with cancer, HF progression is associated with a change in LV myocardial fibroblast growth and function, and expresses a protein signature not dissimilar to the CAF. The overall goal of this review is to put forward the postulate that scientific discoveries regarding FAP in cancer as well as the development of specific chemotherapeutics could be pivoted to target the emergence of FAP in the activated fibroblast subtype and thus hold translationally relevant diagnostic and therapeutic targets in HF.

Targeting tumor and bone microenvironment: Novel therapeutic opportunities for castration-resistant prostate cancer patients with bone metastasis

Despite standard hormonal therapy that targets the androgen receptor (AR) attenuates prostate cancer (PCa) effectively in the initial stage, the tumor ultimately converts to castration-resistant prostate cancer (CRPC), and the acquired resistance is still a great challenge for the management of advanced prostate cancer patients. The tumor microenvironment (TME) consists of multiple cellular and noncellular agents is well known as a vital role during the development and progression of CRPC by establishing communication between TME and tumor cells. Additionally, as primary prostate cancer progresses towards metastasis, and CRPC always experiences bone metastasis, the TME is conducive to the spread of tumors to the distant sits, particularly in bone. In addition, the bone microenvironment (BME) is also closely related to the survival, growth and colonization of metastatic tumor cells. The present review summarized the recent studies which mainly focused on the role of TME or BME in the CRPC patients with bone metastasis, and discussed the underlying mechanisms, as well as the potential therapeutic values of targeting TME and BME in the management of metastatic CRPC patients.

Ratiometric Inclusion of Fibroblasts Promotes Both Castration-Resistant and Androgen-Dependent Tumorigenic Progression in Engineered Prostate Cancer Tissues

To investigate the ratiometric role of fibroblasts in prostate cancer (PCa) progression, this work establishes a matrix-inclusive, 3D engineered prostate cancer tissue (EPCaT) model that enables direct coculture of neuroendocrine-variant castration-resistant (CPRC-ne) or androgen-dependent (ADPC) PCa cells with tumor-supporting stromal cell types. Results show that the inclusion of fibroblasts within CRPC-ne and ADPC EPCaTs drives PCa aggression through significant matrix remodeling and increased proliferative cell populations. Interestingly, this is observed to a much greater degree in EPCaTs formed with a small number of fibroblasts relative to the number of PCa cells. Fibroblast coculture also results in ADPC behavior more similar to the aggressive CRPC-ne condition, suggesting fibroblasts play a role in elevating PCa disease state and may contribute to the ADPC to CRPC-ne switch. Bulk transcriptomic analyses additionally elucidate fibroblast-driven enrichment of hallmark gene sets associated with tumorigenic progression. Finally, the EPCaT model clinical relevancy is probed through a comparison to the Cancer Genome Atlas (TCGA) PCa patient cohort; notably, similar gene set enrichment is observed between EPCaT models and the patient primary tumor transcriptome. Taken together, study results demonstrate the potential of the EPCaT model to serve as a PCa-mimetic tool in future therapeutic development efforts.

Mechanistic Insights on Localized to Metastatic Prostate Cancer Transition and Therapeutic Opportunities

Prostate cancer is the most common non-cutaneous cancer among American men. Multiple mechanisms are involved in tumorigenesis and progression to metastases. While androgen deprivation therapy remains the cornerstone of treatment, progression to castration-resistant disease becomes inevitable. Aberrant pathway activations of PI3K/AKT due to PTEN loss, epithelial-mesenchymal transition pathways, homologous recombination repair, and DNA repair pathway mechanisms of resistance and cross-talk lead to opportunities for therapeutic targeting in metastatic castration-resistant prostate cancer. This review focuses on mechanisms of progression and key trials that evaluate the drugs and combinations that exploit these pathways.

Prostate Cancer Microvascular Routes: Exploration and Measurement Strategies

Angiogenesis is acknowledged as a pivotal feature in the pathology of human cancer. Despite the absence of universally accepted markers for gauging the comprehensive angiogenic activity in prostate cancer (PCa) that could steer the formulation of focused anti-angiogenic treatments, the scrutiny of diverse facets of tumoral blood vessel development may furnish significant understanding of angiogenic processes. Malignant neoplasms, encompassing PCa, deploy a myriad of strategies to secure an adequate blood supply. These modalities range from sprouting angiogenesis and vasculogenesis to intussusceptive angiogenesis, vascular co-option, the formation of mosaic vessels, vasculogenic mimicry, the conversion of cancer stem-like cells into tumor endothelial cells, and vascular pruning. Here we provide a thorough review of these angiogenic mechanisms as they relate to PCa, discuss their prospective relevance for predictive and prognostic evaluations, and outline the prevailing obstacles in quantitatively evaluating neovascularization via histopathological examinations.

A 12-gene panel in estimating hormone-treatment responses of castration-resistant prostate cancer patients generated using a combined analysis of bulk and single-cell sequencing data

BACKGROUND

Castration-resistant prostate cancer (CRPC) represents one type of advanced prostate cancer (PCa) with a median survival time of 1-2 years. Currently, there is a lack of reliable gene panels in predicting hormone treatment (HT) responses due to limited knowledge of CRPC-specific tumor-microenvironment (TME) characteristics.

METHODS

In this study, we first screened for up-regulated genes in CRPC samples using bulk-sequencing data retrieved from TCGA online database, and further investigated the expression status of these genes in four sets of downloaded single-cell RNA sequencing (scRNAseq) data: GSE117403 containing 16 normal human prostate samples; GSE141445 containing 13 PCa samples; GSE176031 containing 11 PCa samples and GSE137829 containing 6 CRPC samples.

RESULTS

We identified a series of CRPC-specific TME characteristics including an enriched number of PEG10+ neuroendocrine cells, elevated expression of PPIB/CCDC74A/GAPDH/AR genes in tumor cells, increased expression of FAP/TGFB1 in cancer-associated fibroblasts (CAFs), suppressed immune environment featured by enhanced M2 macrophage polarization, T cell exhaustion and increased number of regulatory B cells. We further established a 12-gene panel using these characteristics and showed that this panel could separate CRPC samples from PCa samples (AUC of 0.78), and CRPC patients with higher panel scores tended to have treatment failure or progression (R = -0.47, p = 0.019).

CONCLUSIONS

Based on these unique TME characteristics of CRPC, we established a prediction tool for estimating the duration of HT responses in PCa treatment. Our results suggest mechanisms by which prostate cancer becomes castrate resistant. Further study of PEG10 (and/or others) to evaluate therapeutic efficacy should be considered.

Molecular basis and therapeutic targets in prostate cancer: A comprehensive review

Prostate cancer is one of the most significant causes of morbidity and mortality in male patients. The incidence increases with age, and it is higher among African Americans. The occurrence of prostate cancer is associated with many risk factors, including genetic and hereditary predisposition. The most common genetic syndromes associated with prostate cancer risk are BRCA-associated hereditary breast and ovarian cancer (HBOC) and Lynch syndrome. Local-regional therapy, i.e., surgery is beneficial in early-stage prostate cancer management. Advanced and metastatic prostate cancers require systemic therapies, including hormonal inhibition, chemotherapy, and targeted agents. Most prostate cancers can be treated by targeting the androgen-receptor pathway and decreasing androgen production or binding to androgen receptors (AR). Castration-resistant prostate cancer (CRPC) usually involves the PI3K/AKT/mTOR pathway and requires targeted therapy. Specific molecular therapy can target mutated cell lines in which DNA defect repair is altered, caused by mutations of BRCA2, partner and localizer of BRCA2 (PALB2), and phosphatase and tensin homolog (PTEN) or the transmembrane protease serine 2-ERG (TMPRSS2-ERG) fusion. Most benefits were demonstrated in cyclin dependent-kinase 12 (CDK12) mutated cell lines when treated with anti-programmed cell death protein 1 (PD1) therapy. Therapies targeting p53 and AKT are the subject of ongoing clinical trials. Many genetic defects are listed as diagnostic, prognostic, and clinically actionable markers in prostate cancer. Androgen receptor splice variant 7 (AR-V7) is an important oncogenic driver and an early diagnostic and prognostic marker, as well as a therapeutic target in hormone-resistant CRPC. This review summarizes the pathophysiological mechanisms and available targeted therapies for prostate cancer.

Calcium signalling pathways in prostate cancer initiation and progression

Cancer cells proliferate, differentiate and migrate by repurposing physiological signalling mechanisms. In particular, altered calcium signalling is emerging as one of the most widespread adaptations in cancer cells. Remodelling of calcium signalling promotes the development of several malignancies, including prostate cancer. Gene expression data from in vitro, in vivo and bioinformatics studies using patient samples and xenografts have shown considerable changes in the expression of various components of the calcium signalling toolkit during the development of prostate cancer. Moreover, preclinical and clinical evidence suggests that altered calcium signalling is a crucial component of the molecular re-programming that drives prostate cancer progression. Evidence points to calcium signalling re-modelling, commonly involving crosstalk between calcium and other cellular signalling pathways, underpinning the onset and temporal progression of this disease. Discrete alterations in calcium signalling have been implicated in hormone-sensitive, castration-resistant and aggressive variant forms of prostate cancer. Hence, modulation of calcium signals and downstream effector molecules is a plausible therapeutic strategy for both early and late stages of prostate cancer. Based on this premise, clinical trials have been undertaken to establish the feasibility of targeting calcium signalling specifically for prostate cancer.

Exploring the Onset and Progression of Prostate Cancer through a Multicellular Agent-based Model

Over 10% of men will be diagnosed with prostate cancer during their lifetime. Arising from luminal cells of the prostatic acinus, prostate cancer is influenced by multiple cells in its microenvironment. To expand our knowledge and explore means to prevent and treat the disease, it is important to understand what drives the onset and early stages of prostate cancer. In this study, we developed an agent-based model of a prostatic acinus including its microenvironment, to allow for in silico studying of prostate cancer development. The model was based on prior reports and in-house data of tumor cells cocultured with cancer-associated fibroblasts (CAF) and protumor and/or antitumor macrophages. Growth patterns depicted by the model were pathologically validated on hematoxylin and eosin slide images of human prostate cancer specimens. We identified that stochasticity of interactions between macrophages and tumor cells at early stages strongly affect tumor development. In addition, we discovered that more systematic deviations in tumor development result from a combinatorial effect of the probability of acquiring mutations and the tumor-promoting abilities of CAFs and macrophages. In silico modeled tumors were then compared with 494 patients with cancer with matching characteristics, showing strong association between predicted tumor load and patients' clinical outcome. Our findings suggest that the likelihood of tumor formation depends on a combination of stochastic events and systematic characteristics. While stochasticity cannot be controlled, information on systematic effects may aid the development of prevention strategies tailored to the molecular characteristics of an individual patient.

Significance

We developed a computational model to study which factors of the tumor microenvironment drive prostate cancer development, with potential to aid the development of new prevention strategies.

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.

Induction of Reactive Bone Stromal Fibroblasts in 3D Models of Prostate Cancer Bone Metastases

A dynamic interplay between prostate cancer (PCa) cells and reactive bone stroma modulates the growth of metastases within the bone microenvironment. Of the stromal cells, metastasis-associated fibroblasts (MAFs) are known to contribute but are the least studied cell type in PCa tumour progression. It is the aim of the current study to establish a biologically relevant 3D in vitro model that mimics the cellular and molecular profiles of MAFs found in vivo. Using 3D in vitro cell culture models, the bone-derived fibroblast cell line, HS-5, was treated with conditioned media from metastatic-derived PCa cell lines, PC3 and MDA-PCa 2b, or mouse-derived fibroblasts 3T3. Two corresponding reactive cell lines were propagated: HS5-PC3 and HS5-MDA, and evaluated for alterations in morphology, phenotype, cellular behaviour, plus protein and genomic profiles. HS5-PC3 and HS5-MDA displayed distinct alterations in expression levels of N-Cadherin, non-functional E-Cadherin, alpha-smooth muscle actin (α-SMA), Tenascin C, and vimentin, along with transforming growth factor receptor expression (TGF β R1 and R2), consistent with subpopulations of MAFs reported in vivo. Transcriptomic analysis revealed a reversion of HS5-PC3 towards a metastatic phenotype with an upregulation in pathways known to regulate cancer invasion, proliferation, and angiogenesis. The exploitation of these engineered 3D models could help further unravel the novel biology regulating metastatic growth and the role fibroblasts play in the colonisation process.

Immunotherapy in Prostate Cancer: State of Art and New Therapeutic Perspectives

Prostate cancer (PC) is the most common type of tumor in men. In the early stage of the disease, it is sensitive to androgen deprivation therapy. In patients with metastatic castration-sensitive prostate cancer (mHSPC), chemotherapy and second-generation androgen receptor therapy have led to increased survival. However, despite advances in the management of mHSPC, castration resistance is unavoidable and many patients develop metastatic castration-resistant disease (mCRPC). In the past few decades, immunotherapy has dramatically changed the oncology landscape and has increased the survival rate of many types of cancer. However, immunotherapy in prostate cancer has not yet given the revolutionary results it has in other types of tumors. Research into new treatments is very important for patients with mCRPC because of its poor prognosis. In this review, we focus on the reasons for the apparent intrinsic resistance of prostate cancer to immunotherapy, the possibilities for overcoming this resistance, and the clinical evidence and new therapeutic perspectives regarding immunotherapy in prostate cancer with a look toward the future.

3D bioprinting of multi-cellular tumor microenvironment for prostate cancer metastasis

Prostate cancer (PCa) is one of the most lethal cancers in men worldwide. The tumor microenvironment (TME) plays an important role in PCa development, which consists of tumor cells, fibroblasts, endothelial cells, and extracellular matrix (ECM). Hyaluronic acid (HA) and cancer-associated fibroblasts (CAFs) are the major components in the TME and are correlated with PCa proliferation and metastasis, while the underlying mechanism is still not fully understood due to the lack of biomimetic ECM components and coculture models. In this study, gelatin methacryloyl/chondroitin sulfate-based hydrogels were physically crosslinked with HA to develop a novel bioink for the three-dimensional bioprinting of a coculture model that can be used to investigate the effect of HA on PCa behaviors and the mechanism underlying PCa-fibroblasts interaction. PCa cells demonstrated distinct transcriptional profiles under HA stimulation, where cytokine secretion, angiogenesis, and epithelial to mesenchymal transition were significantly upregulated. Further coculture of PCa with normal fibroblasts activated CAF transformation, which could be induced by the upregulated cytokine secretion of PCa cells. These results suggested HA could not only promote PCa metastasis individually but also induce PCa cells to activate CAF transformation and form HA-CAF coupling effects to further promote PCa drug resistance and metastasis.

Advances in landscape and related therapeutic targets of the prostate tumor microenvironment

The distinct tumor microenvironment (TME) of prostate cancer (PCa), which promotes tumor proliferation and progression, consists of various stromal cells, immune cells, and a dense extracellular matrix (ECM). The understanding of the prostate TME extends to tertiary lymphoid structures (TLSs) and metastasis niches to provide a more concise comprehension of tumor metastasis. These constituents collectively structure the hallmarks of the pro-tumor TME, including immunosuppressive, acidic, and hypoxic niches, neuronal innervation, and metabolic rewiring. In combination with the knowledge of the tumor microenvironment and the advancement of emerging therapeutic technologies, several therapeutic strategies have been developed, and some of them have been tested in clinical trials. This review elaborates on PCa TME components, summarizes various TME-targeted therapies, and provides insights into PCa carcinogenesis, progression, and therapeutic strategies.

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.

SFRP1 induces a stem cell phenotype in prostate cancer cells

Prostate cancer (PCa) ranks second in incidence and sixth in deaths globally. The treatment of patients with castration-resistant prostate cancer (CRPC) continues to be a significant clinical problem. Emerging evidence suggests that prostate cancer progression toward castration resistance is associated with paracrine signals from the stroma. SFRP1 is one of the extracellular proteins that modulate the WNT pathway, and it has been identified as a mediator of stromal epithelium communication. The WNT pathway is involved in processes such as cell proliferation, differentiation, cell anchoring, apoptosis, and cell cycle regulation as well as the regulation of stem cell populations in the prostatic epithelium. In the present study, we explored the role of exogenous SFRP1 on the stem cell phenotype in prostate cancer. The results reveal that cancer stem cell markers are significantly increased by exogenous SFRP1 treatments, as well as the downstream target genes of the Wnt/-catenin pathway. The pluripotent transcription factors SOX2, NANOG, and OCT4 were also up-regulated. Furthermore, SFRP1 promoted prostate cancer stem cell (PCSC) properties in vitro, including tumorsphere formation, migration, bicalutamide resistance, and decreased apoptosis. Taken together, our results indicate that SFRP1 participates in the paracrine signaling of epithelial cells, influencing them and positively regulating the stem cell phenotype through deregulation of the WNT/β-catenin pathway, which could contribute to disease progression and therapeutic failure. This research increases our molecular understanding of how CRPC progresses, which could help us find new ways to diagnose and treat the disease.

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.

Dissecting the immune suppressive human prostate tumor microenvironment via integrated single-cell and spatial transcriptomic analyses

The treatment of low-risk primary prostate cancer entails active surveillance only, while high-risk disease requires multimodal treatment including surgery, radiation therapy, and hormonal therapy. Recurrence and development of metastatic disease remains a clinical problem, without a clear understanding of what drives immune escape and tumor progression. Here, we comprehensively describe the tumor microenvironment of localized prostate cancer in comparison with adjacent normal samples and healthy controls. Single-cell RNA sequencing and high-resolution spatial transcriptomic analyses reveal tumor context dependent changes in gene expression. Our data indicate that an immune suppressive tumor microenvironment associates with suppressive myeloid populations and exhausted T-cells, in addition to high stromal angiogenic activity. We infer cell-to-cell relationships from high throughput ligand-receptor interaction measurements within undissociated tissue sections. Our work thus provides a highly detailed and comprehensive resource of the prostate tumor microenvironment as well as tumor-stromal cell interactions.

Cell-Type-Specific Signalling Networks Impacted by Prostate Epithelial-Stromal Intercellular Communication

Prostate cancer is the second most common cause of cancer death in males. A greater understanding of cell signalling events that occur within the prostate cancer tumour microenvironment (TME), for example, between cancer-associated fibroblasts (CAFs) and prostate epithelial or cancer cells, may identify novel biomarkers and more effective therapeutic strategies for this disease. To address this, we used cell-type-specific labelling with amino acid precursors (CTAP) to define cell-type-specific (phospho)proteomic changes that occur when prostate epithelial cells are co-cultured with normal patient-derived prostate fibroblasts (NPFs) versus matched CAFs. We report significant differences in the response of BPH-1 benign prostate epithelial cells to CAF versus NPF co-culture. Pathway analysis of proteomic changes identified significant upregulation of focal adhesion and cytoskeleton networks, and downregulation of metabolism pathways, in BPH-1 cells cultured with CAFs. In addition, co-cultured CAFs exhibited alterations in stress, DNA damage, and cytoskeletal networks. Functional validation of one of the top differentially-regulated proteins in BPH-1 cells upon CAF co-culture, transglutaminase-2 (TGM2), demonstrated that knockdown of this protein significantly reduced the proliferation and migration of prostate epithelial cells. Overall, this study provides novel insights into intercellular communication in the prostate cancer TME that may be exploited to improve patient management.

Immune-related gene index predicts metastasis for prostate cancer patients undergoing radical radiotherapy

In this study, we established a novel immunologic gene prognostic index (IGPI) to predict metastasis and provided new insights into tumor immune microenvironment (TIME) for PCa patients receiving radical radiotherapy. GBP2 and IGF1 were independent factors associated with metastasis-free survival. IGPI score was calculated based on GBP2 and IGF1 and this score was an independent risk factor for PCa patients undergoing radical radiotherapy. Patients with higher IGPI score were at higher risk of metastasis and biochemical recurrence, which were externally validated in the TCGA database and other GEO datasets. IGPI score had demonstrated moderate diagnostic ability of radiation resistance (AUC: 0.889). This score increased with the augment of Gleason score and T stage, as well as biochemical recurrence. Using EPIC, ESTIMATE and immunophenoscore (IPS) algorithms, cancer associated fibroblasts (CAFs), macrophages, stromal score, and estimate score were significantly higher in patients with metastasis group compared to their counterpart. Besides, for CAFs, macrophages, stromal score, and estimate score, patients with higher scores were at higher risk of metastasis, and the HRs were 3.65, 4.01, 4.27, and 3.78, respectively. IGPI score was highly positively associated with stromal score (coefficient: 0.39), immune score (coefficient: 0.43), estimate score (coefficient: 0.45), CAFs (coefficient: 0.42) and macrophages (coefficient: 0.42), while showing the opposite relationship with tumor purity (coefficient: - 0.45). In conclusion, we found that IGPI based on GBP2 and IGF1 might serve as a biomarker predicting metastasis for PCa patients. Besides, the current data further highlight the importance of CAFs in the metastatic process of 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.

Dickkopf-3: An Update on a Potential Regulator of the Tumor Microenvironment

Dickkopf-3 (Dkk-3) is a member of the Dickkopf family protein of secreted Wingless-related integration site (Wnt) antagonists that appears to modulate regulators of the host microenvironment. In contrast to the clear anti-tumorigenic effects of Dkk-3-based gene therapies, the role of endogenous Dkk-3 in cancer is context-dependent, with elevated expression associated with tumor promotion and suppression in different settings. The receptors and effectors that mediate the diverse effects of Dkk-3 have not been characterized in detail, contributing to an ongoing mystery of its mechanism of action. This review compares the various functions of Dkk-3 in the tumor microenvironment, where Dkk-3 has been found to be expressed by subpopulations of fibroblasts, endothelial, and immune cells, in addition to epithelial cells. We also discuss how the activation or inhibition of Dkk-3, depending on tumor type and context, might be used to treat different types of cancers.

Effects of urinary extracellular vesicles from prostate cancer patients on the transcriptomes of cancer-associated and normal fibroblasts

BACKGROUND

Increasing evidence suggests that cancer-derived extracellular vesicles (EVs) alter the phenotype and functions of fibroblasts and trigger the reprogramming of normal fibroblasts into cancer-associated fibroblasts (CAFs). Here, we for the first time studied the effects of urinary EVs from PC patients and healthy males on the transcriptional landscape of prostate CAFs and normal foreskin fibroblasts.

METHODS

Patient-derived prostate fibroblast primary cultures PCF-54 and PCF-55 were established from two specimens of PC tissues. EVs were isolated from urine samples of 3 patients with PC and 2 healthy males and used for the treatment of prostate fibroblast primary cultures and normal foreskin fibroblasts. The EV-treated fibroblasts were subjected to RNA sequencing analysis.

RESULTS

RNA sequencing analysis showed that the fibroblast cultures differed significantly in their response to urinary EVs. The transcriptional response of foreskin fibroblasts to the urinary EVs isolated from PC patients and healthy controls was very similar and mostly related to the normal functions of fibroblasts. On the contrary, PCF-54 cells responded very differently - EVs from PC patients elicited transcriptional changes related to the regulation of the cell division and chromosome segregation, whereas EVs from healthy males affected mitochondrial respiration. In PCF-55 cells, EVs from both, PC-patients and controls induced the expression of a number of chemokines such as CCL2, CCL13, CXCL1, CXCL8, whereas pathways related to regulation of apoptotic signaling and production of cell adhesion molecules were triggered specifically by EVs from PC patients.

CONCLUSION

This study demonstrates that urinary EVs from PC patients and healthy controls elicit distinct transcriptional responses in prostate CAFs and supports the idea that EVs contribute to the generation of functional heterogeneity of CAFs. Moreover, this study suggests that the changes in the gene expression pattern in EV recipient cells might serve as a novel type of functional cancer biomarkers.

Cancer-associated fibroblast-derived gene signatures predict radiotherapeutic survival in prostate cancer patients

BACKGROUND

Cancer-associated fibroblasts (CAFs) play multiple roles in regulating tumor metastasis and treatment response. Current clinical indicators are insufficient to accurately assess disease risk and radiotherapy response, emphasizing the urgent need for additional molecular prognostic markers.

METHODS

In order to investigate CAF-related genes associated with radiotherapy and construct prognostic CAF-related gene signatures for prostate cancer, we firstly established a radio-resistant prostate CAF cell subline (referred to as CAFR) from Mus-CAF (referred to as CAF) through fractionated irradiation using X-rays. Transcriptome sequencing for CAF and CAFR was conducted, and 2626 CAF-related differentially expressed genes (DEGs) associated with radiotherapy were identified. Human homologous genes of mouse CAF-related DEGs were then obtained.

RESULTS

Functional enrichment analysis revealed that these CAF-related DEGs were significantly enriched ECM- and immune-related functions and pathways. Based on GSE116918 dataset, 186 CAF-related DEGs were correlated with biochemical recurrence-free survival (BCRFS) of prostate cancer patients, 16 of which were selected to construct a BCRFS-related CAF signature, such as ACPP, THBS2, and KCTD14; 142 CAF-related DEGs were correlated with metastasis-free survival (MFS), 16 of which were used to construct a MFS-related CAF signature, such as HOPX, TMEM132A, and ZNF467. Both Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets confirmed that the two CAF signatures accurately predicted BCRFS and MFS of prostate cancer patients. The risk scores were higher in patients with higher gleason grades and higher clinical T stages. Moreover, the BCRFS-related CAF signature was an independent prognostic factor and a nomogram consisting of BCRFS-related CAF signature and various clinical factors accurately predicted 2-, 3-, and 5-year survival time of prostate cancer patients. Furthermore, the risk score was positively correlated with multiple immune checkpoints.

CONCLUSIONS

Our established CAF signatures could accurately predict BCRFS and MFS in prostate cancer patients undergoing radiotherapy.

Metabolic changes during prostate cancer development and progression

Metabolic reprogramming has been recognised as a hallmark in solid tumours. Malignant modification of the tumour's bioenergetics provides energy for tumour growth and progression. Otto Warburg first reported these metabolic and biochemical changes in 1927. In prostate cancer (PCa) epithelial cells, the tumour metabolism also changes during development and progress. These alterations are partly driven by the androgen receptor, the key regulator in PCa development, progress, and survival. In contrast to other epithelial cells of different entities, glycolytic metabolism in prostate cells sustains physiological citrate secretion in the normal prostatic epithelium. In the early stages of PCa, citrate is utilised to power oxidative phosphorylation and fuel lipogenesis, enabling tumour growth and progression. In advanced and incurable castration-resistant PCa, a metabolic shift towards choline, amino acid, and glycolytic metabolism fueling tumour growth and progression has been described. Therefore, even if the metabolic changes are not fully understood, the altered metabolism during tumour progression may provide opportunities for novel therapeutic strategies, especially in advanced PCa stages. This review focuses on the main differences in PCa's metabolism during tumourigenesis and progression highlighting glutamine's role in PCa.

Interplay between Prostate Cancer and Adipose Microenvironment: A Complex and Flexible Scenario

Adipose tissue is part of the prostate cancer (PCa) microenvironment not only in the periprostatic area, but also in the most frequent metastatic sites, such as bone marrow and pelvic lymph nodes. The involvement of periprostatic adipose tissue (PPAT) in the aggressiveness of PCa is strongly suggested by numerous studies. Many molecules play a role in the reciprocal interaction between adipocytes and PCa cells, including adipokines, hormones, lipids, and also lipophilic pollutants stored in adipocytes. The crosstalk has consequences not only on cancer cell growth and metastatic potential, but also on adipocytes. Although most of the molecules released by PPAT are likely to promote tumor growth and the migration of cancer cells, others, such as the adipokine adiponectin and the n-6 or n-3 polyunsaturated fatty acids (PUFAs), have been shown to have anti-tumor properties. The effects of PPAT on PCa cells might therefore depend on the balance between the pro- and anti-tumor components of PPAT. In addition, genetic and environmental factors involved in the risk and/or aggressiveness of PCa, including obesity and diet, are able to modulate the interactions between PPAT and cancer cells and their consequences on the growth and the metastatic potential of PCa.

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.

Focus on the tumor microenvironment: A seedbed for neuroendocrine prostate cancer

The tumor microenvironment (TME) is a microecology consisting of tumor and mesenchymal cells and extracellular matrices. The TME plays important regulatory roles in tumor proliferation, invasion, metastasis, and differentiation. Neuroendocrine differentiation (NED) is a mechanism by which castration resistance develops in advanced prostate cancer (PCa). NED is induced after androgen deprivation therapy and neuroendocrine prostate cancer (NEPC) is established finally. NEPC has poor prognosis and short overall survival and is a major cause of death in patients with PCa. Both the cellular and non-cellular components of the TME regulate and induce NEPC formation through various pathways. Insights into the roles of the TME in NEPC evolution, growth, and progression have increased over the past few years. These novel insights will help refine the NEPC formation model and lay the foundation for the discovery of new NEPC therapies targeting the TME.

Fatty Acid Signaling Impacts Prostate Cancer Lineage Plasticity in an Autocrine and Paracrine Manner

Prostate cancer (PCa) affects an estimated 250,000 men every year and causes 34,000 deaths annually. A high-fat diet and obesity are associated with PCa progression and mortality. This study's premise was the novel observation of crosstalk between PCa epithelia and cancer-associated fibroblasts (CAF) in response to palmitate-mediated lineage plasticity. We found that cholesterol activated canonical Hedgehog (Hh) signaling by increasing cilium Gli activity in PCa cells, while palmitate activated Hh independent of Gli. Exogenous palmitate activated SOX2, a known mediator of lineage plasticity, in PCa cells cocultured with CAF. Stroma-derived Wnt5a was upregulated in CAF while cocultured with PCa cells and treated with palmitate. Wnt5a knockdown in CAF inhibited Hh and SOX2 expression in PCa cells from cocultures. These findings supported our proposed mechanism of a high-fat diet promoting Hh signaling-mediated transformation within the tumor microenvironment. SOX2 and Wnt5a expression were limited by the CD36 neutralizing antibody. Mice xenografted with PCa epithelia and CAF tumors were fed a high-fat diet, leading to elevated SOX2 expression and lineage plasticity reprogramming compared to mice fed an isocaloric rodent diet. CD36 inhibition with enzalutamide elevated apoptosis by TUNEL, but limited proliferation and SOX2 expression compared to enzalutamide alone. This study revealed a mechanism for a high-fat diet to affect prostate cancer progression. We found that saturated fat induced lineage plasticity reprogramming of PCa by interaction with CAF through Wnt5a and Hh signaling.

Gene Expression Profile of Stromal Factors in Cancer-Associated Fibroblasts from Prostate Cancer

Recent investigations point at the stromal microenvironment to assess additional diagnostic information and provide new therapeutic targets in cancer. The aim of the study was to contribute to the characterization of the phenotype of cancer-associated fibroblasts (CAFs) in prostate cancer (PCa) compared with normal prostate-associated fibroblasts (NAFs) and fibroblasts from benign prostatic hyperplasia (BPH). Three patient populations were prospectively recruited: 23 patients with new localized PCa, 14 patients with advanced PCa treated with androgenic deprivation therapy (ADT), and 7 patients with BPH. Gene expression of 20 stroma-derived factors, including the androgen receptor (AR), chaperones (HSPA1A and HSF1), growth factors (FGF2, FGF7, FGF10, HGF, PDGFB, and TGFβ), proteins implicated in invasion (MMP2, MMP9, and MMP11), inflammation (IL6, IL17RB, NFκB, and STAT3), and in-stroma/epithelium interaction (CDH11, CXCL12, CXCL14, and FAP), was evaluated. Localized PCa CAFs showed a significant higher expression of FGF7, IL6, MMP2, and MMP11 compared with NAFs or IL17RB compared with BPH fibroblasts, but significantly lower expression of FGF10 and IL17RB compared with NAFs or CXCL14 compared with BPH fibroblasts. In addition, CAFs from ADT-resistant PCa showed significantly higher MMP11 and NFκB but significant lower TGFβ expression compared with CAFs from ADT-sensitive tumors. Our results contribute to defining the CAFs phenotypes associated to PCa progression, which may contribute to the diagnosis and design of alternative therapies in PCa.

Cancer-Associated Fibroblasts Promote Tumor Aggressiveness in Head and Neck Cancer through Chemokine Ligand 11 and C-C Motif Chemokine Receptor 3 Signaling Circuit

Simple Summary

Certain tumor aggressiveness-associated mediators from cancer-associated fibroblasts (CAFs) in tumor microenvironment have been reported. Using gene expression analysis, we identified that CAFs overexpress Chemokine ligand 11 (CCL11), which is associated with tumor migration and invasion, increased expression of cancer stem cell properties, and induction of the epithelial-to-mesenchymal transition. Neutralization of CAF-induced CCL11 reversed the aggressive phenotype of cancer cells. Based on the immunohistochemical staining of clinical samples, we found that increased co-expression of CCL11 and its receptor, C-C Motif Chemokine Receptor 3 (CCR3), was associated with poor overall survival. Our results suggest that targeting CCL11-CCR3 signaling is a potential therapeutic strategy for patients with aggressive head and neck cancer.

Abstract

The tumor microenvironment (TME) plays a crucial role in tumor progression. One of its key stromal components, cancer-associated fibroblasts (CAFs), may crosstalk with cancer cells by secreting certain cytokines or chemokines. However, which important mediator(s) are released by CAFs, and the underlying molecular mechanism, remain largely unknown. In the present study, we isolated patient-derived CAFs and normal fibroblasts (NFs). Using microarray analysis, we detected chemokine ligand 11 (CCL11) overexpression in CAFs compared to NFs. CCL11 administration promoted the migration and invasion of head and neck cancer (HNC) cells with enhanced cancer stem cell-like properties and induction of epithelial-to-mesenchymal transition. Furthermore, neutralization of CCL11 activity reversed the aggressive phenotype of CAF-induced cancer cells. Confocal microscopy showed colocalization of CCL11 and CC chemokine receptor 3 (CCR3) on HNC cells. Moreover, immunohistochemical analysis of clinical samples from 104 patients with HNC showed that expression of CCL11 and CCR3 were significantly correlated with poor overall survival (p = 0.003 and 0.044, respectively). Collectively, CCL11 expressed on CAFs promotes HNC invasiveness, and neutralization of CCL11 reverses this effect. We propose that the CCL11/CCR3 signaling circuit is a potential target for optimizing therapeutic strategies against HNC.

Molecular Characterization of Cancer Associated Fibroblasts in Prostate Cancer

BACKGROUND

Stromal components surrounding epithelial cancer cells seem to play a pivotal role during epithelial-to-mesenchymal transition (EMT), tumor invasion, and metastases. To identify the molecular mechanisms underlying tumor-stroma interactions may yield novel therapeutic targets for prostate cancer.

METHODS

Gene expression profile of prostate-cancer associated fibroblast (PCAF) and prostate non-cancer associated fibroblast (PNAF) cells isolated from radical prostatectomy was performed by Illumina, analyzed, and further processed by Ingenuity^®: IPA^® software. qRT-PCR was performed on an independent set of 17 PCAF, 12 PNAF, and 12 fibroblast cell lines derived from patients with benign prostatic hyperplasia (BPHF).

RESULTS

Using microarray analysis, we found six upregulated genes and two downregulated genes in PCAFs compared to PNAFs. To validate microarray results, we performed qRT-PCR for the most significantly regulated genes involved in the modulation of proliferation and androgen resistance on an independent set of PNAF, PCAF, and BHPF samples. We confirmed the increased expression of SCARB1, MAPK3K1, and TGF-β as well as the decreased expression of S100A10 in PCAFs compared to PNAFs and BPHFs.

CONCLUSIONS

These results provide strong evidence that the observed changes in the gene expression profile of PCAFs can contribute to functional alteration of adjacent prostate cancer cells.

The complex role of telocytes in female prostate tumorigenesis in a rodent model

The prostate is not an organ exclusive to the male. It is also found in females of several species, including humans, in which part of the Skene gland is homologous to the male prostate. Evidence is accumulating that changes in the stroma are central to tumorigenesis. Equally, telocytes, a recently discovered type of interstitial cell, are essential for the maintenance of stromal organization. However, it is still uncertain whether there are telocytes in the female prostate and if they play a role in tumorigenesis. The present study used ultrastructural and immunofluorescence techniques to investigate the presence of telocytes in the prostate of Mongolian gerbil females, a rodent model that often has a functional prostate in females, as well as to assess the impact of a combination of N-ethyl-N-nitrosourea, testosterone, and estradiol on telocytes. The results point to the presence of telocytes in the female prostate in the perialveolar and interalveolar regions, and reveal that these cells are absent in regions of benign and premalignant lesions in the gland, in which the perialveolar smooth muscle is altered. Additionally, telocytes are also closely associated with infiltrated immune cells in the stroma. Our data suggest that telocytes are important for both the maintenance of smooth muscle and prostatic epithelium integrity, which indicates a protective role against the advancement of tumorigenesis. But telocytes are also associated with immune cells and a proinflammatory/proangiogenic role for these cells cannot be ruled out, implying that telocytes have a complex role in prostatic tumorigenesis in females.

Ephrin B Activate Src Family Kinases in Fibroblasts Inducing Stromal Remodeling in Prostate Cancer

Simple Summary

Carcinoma associated fibroblasts (CAF) play a critical role in the tumor microenvironment (TME) of prostate cancer (PCa). Ephrin receptors (Eph) and ligands (EFN) have been implicated in distinct types of cancers. Alterations on EphB receptors are frequently found in PCa, but the role of ligands (EFNB1, EFNB2, EFNB3) activation in prostate fibroblasts and consequent effects on PCa is not known. We found increased EFNB ligands in fibroblasts isolated from PCa tissues. In this study, we assessed the effects of elevated stromal EFNB ligands on PCa tumor growth. Increased EFNB1 and EFNB3 expression transformed normal fibroblasts into CAF phenotypes through activation of Src family kinases. The secretome of EFNB-expressing CAF increased PCa cell proliferation and promoted TME remodeling. Overall, EFNB activation in CAF may participate in PCa progression via the release of soluble factors that modulate the surrounding tumor environment, which, in turn, promote prostate tumor growth and invasion.

Abstract

Through stromal-epithelial interactions, carcinoma associated fibroblasts (CAF) play a critical role in tumor growth and progression. Activation of erythrophoyetin-producing human hepatocellular (Eph) receptors has been implicated in cancer. Eph receptor interactions with Ephrin ligands lead to bidirectional signals in the recipient and effector cells. The consequences of continuous reverse Ephrin signaling activation in fibroblasts on prostate cancer (PCa) is unknown. When compared to benign prostate fibroblast, CAF displayed higher expression of Ephrin B1, B2, and B3 ligands (EFNB1, EFNB2, and EFNB3). In this study, we found that continuous activation of EFNB1 and EFNB3 in a benign human prostate stromal cell line (BHPrS1) increased the expression of CAF markers and induced a CAF phenotype. BHPrS1^EFNB1 and BHPrS1^EFNB3 displayed a pro-tumorigenic secretome with multiple effects on neovascularization, collagen deposition, and cancer cell proliferation, overall increasing tumorigenicity of a premalignant prostate epithelial cell line BPH1 and PCa cell line LNCaP, both in vitro and in vivo. Inhibition of Src family kinases (SFK) in BHPrS1^EFNB1 and BHPrS1^EFNB3 suppressed EFNB-induced ɑ-SMA (Alpha-smooth muscle actin) and TN-C (Tenascin-C) in vitro. Our study suggests that acquisition of CAF characteristics via SFK activation in response to increased EFNB ligands could promote carcinogenesis via modulation of TME in PCa.

Tumor microenvironment mechanisms and bone metastatic disease progression of prostate cancer

During disease progression from primary towards metastatic prostate cancer (PCa), and in particular bone metastases, the tumor microenvironment (TME) evolves in parallel with the cancer clones, altering extracellular matrix composition (ECM), vasculature architecture, and recruiting specialized tumor-supporting cells that favor tumor spread and colonization at distant sites. We introduce the clinical profile of advanced metastatic PCa in terms of common genetic alterations. Findings from recently developed models of PCa metastatic spread are discussed, focusing mainly on the role of the TME (mainly matrix and fibroblast cell types), at distinct stages: premetastatic niche orchestrated by the primary tumor towards the metastatic site and bone metastasis. We report evidence of premetastatic niche formation, such as the mechanisms of distant site conditioning by extracellular vesicles, chemokines and other tumor-derived mechanisms, including altered cancer cell-ECM interactions. Furthermore, evidence supporting the similarities of stroma alterations among the primary PCa and bone metastasis, and contribution of TME to androgen deprivation therapy resistance are also discussed. We summarize the available bone metastasis transgenic mouse models of PCa from a perspective of pro-metastatic TME alterations during disease progression and give an update on the current diagnostic and therapeutic radiological strategies for bone metastasis clinical management.

Proteomics Approach Highlights Early Changes in Human Fibroblasts-Pancreatic Ductal Adenocarcinoma Cells Crosstalk

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer mortality worldwide. Non-specific symptoms, lack of biomarkers in the early stages, and drug resistance due to the presence of a dense fibrous stroma all contribute to the poor outcome of this disease. The extracellular matrix secreted by activated fibroblasts contributes to the desmoplastic tumor microenvironment formation. Given the importance of fibroblast activation in PDAC pathology, it is critical to recognize the mechanisms involved in the transformation of normal fibroblasts in the early stages of tumorigenesis. To this aim, we first identified the proteins released from the pancreatic cancer cell line MIA-PaCa2 by proteomic analysis of their conditioned medium (CM). Second, normal fibroblasts were treated with MIA-PaCa2 CM for 24 h and 48 h and their proteostatic changes were detected by proteomics. Pathway analysis indicated that treated fibroblasts undergo changes compatible with the activation of migration, vasculogenesis, cellular homeostasis and metabolism of amino acids and reduced apoptosis. These biological activities are possibly regulated by ITGB3 and TGFB1/2 followed by SMAD3, STAT3 and BAG3 activation. In conclusion, this study sheds light on the crosstalk between PDAC cells and associated fibroblasts. Data are available via ProteomeXchange with identifier PXD030974.

Patterns of indolence in prostate cancer (Review)

Although prostate cancer is a major cause of cancer-related mortality worldwide, most patients will have a relatively indolent clinical course. Contrary to most other types of cancer, even the diagnosis of locally advanced or metastatic disease is not always lethal. The present review aimed to summarize what is known regarding the underlying mechanisms related to the indolent course of subsets of prostate cancer, at various stages. The data suggested that no specific gene alteration by itself was responsible for carcinogenesis or disease aggressiveness. However, pathway analysis identified genetic aberrations in multiple critical pathways that tend to accumulate over the course of the disease. The progression from indolence into aggressive disease is associated with a complex interplay in which genetic and epigenetic factors are involved. The effect of the immune tumor microenvironment is also very important. Emerging evidence has suggested that the upregulation of pathways related to cellular aging and senescence can identify patients with indolent disease. In addition, a number of tumors enter a long-lasting quiescent state. Further research will determine whether halting tumor evolution is a feasible option, and whether the life of patients can be markedly prolonged by inducing tumor senescence or long-term dormancy.

Integrins and Epithelial-Mesenchymal Cooperation in the Tumor Microenvironment of Muscle-Invasive Lethal Cancers

Muscle-invasive lethal carcinomas traverse into and through this specialized biophysical and growth factor enriched microenvironment. We will highlight cancers that originate in organs surrounded by smooth muscle, which presents a barrier to dissemination, including prostate, bladder, esophageal, gastric, and colorectal cancers. We propose that the heterogeneity of cell-cell and cell-ECM adhesion receptors is an important driver of aggressive tumor networks with functional consequences for progression. Phenotype heterogeneity of the tumor provides a biophysical advantage for tumor network invasion through the tensile muscle and survival of the tumor network. We hypothesize that a functional epithelial-mesenchymal cooperation (EMC)exists within the tumor invasive network to facilitate tumor escape from the primary organ, invasion and traversing of muscle, and navigation to metastatic sites. Cooperation between specific epithelial cells within the tumor and stromal (mesenchymal) cells interacting with the tumor is illustrated using the examples of laminin-binding adhesion molecules—especially integrins—and their response to growth and inflammatory factors in the tumor microenvironment. The cooperation between cell-cell (E-cadherin, CDH1) and cell-ECM (α6 integrin, CD49f) expression and growth factor receptors is highlighted within poorly differentiated human tumors associated with aggressive disease. Cancer-associated fibroblasts are examined for their role in the tumor microenvironment in generating and organizing various growth factors. Cellular structural proteins are potential utility markers for future spatial profiling studies. We also examine the special characteristics of the smooth muscle microenvironment and how invasion by a primary tumor can alter this environment and contribute to tumor escape via cooperation between epithelial and stromal cells. This cooperative state allows the heterogenous tumor clusters to be shaped by various growth factors, co-opt or evade immune system response, adapt from hypoxic to normoxic conditions, adjust to varying energy sources, and survive radiation and chemotherapeutic interventions. Understanding the epithelial-mesenchymal cooperation in early tumor invasive networks holds potential for both identifying early biomarkers of the aggressive transition and identification of novel agents to prevent the epithelial-mesenchymal cooperation phenotype. Epithelial-mesenchymal cooperation is likely to unveil new tumor subtypes to aid in selection of appropriate therapeutic strategies.