The tumor microenvironment in prostate cancer: elucidating molecular pathways for therapy development

Prediction of Clinically Significant Prostate Cancer by a Specific Collagen-related Transcriptome, Proteome, and Urinome Signature

BACKGROUND AND OBJECTIVE

While collagen density has been associated with poor outcomes in various cancers, its role in prostate cancer (PCa) remains elusive. Our aim was to analyze collagen-related transcriptomic, proteomic, and urinome alterations in the context of detection of clinically significant PCa (csPCa, International Society of Urological Pathology [ISUP] grade group ≥2).

METHODS

Comprehensive analyses for PCa transcriptome (n = 1393), proteome (n = 104), and urinome (n = 923) data sets focused on 55 collagen-related genes. Investigation of the cellular source of collagen-related transcripts via single-cell RNA sequencing was conducted. Statistical evaluations, clustering, and machine learning models were used for data analysis to identify csPCa signatures.

KEY FINDINGS AND LIMITATIONS

Differential expression of 30 of 55 collagen-related genes and 34 proteins was confirmed in csPCa in comparison to benign prostate tissue or ISUP 1 cancer. A collagen-high cancer cluster exhibited distinct cellular and molecular characteristics, including fibroblast and endothelial cell infiltration, intense extracellular matrix turnover, and enhanced growth factor and inflammatory signaling. Robust collagen-based machine learning models were established to identify csPCa. The models outcompeted prostate-specific antigen (PSA) and age, showing comparable performance to multiparametric magnetic resonance imaging (mpMRI) in predicting csPCa. Of note, the urinome-based collagen model identified four of five csPCa cases among patients with Prostate Imaging-Reporting and Data System (PI-IRADS) 3 lesions, for which the presence of csPCa is considered equivocal. The retrospective character of the study is a limitation.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Collagen-related transcriptome, proteome, and urinome signatures exhibited superior accuracy in detecting csPCa in comparison to PSA and age. The collagen signatures, especially in cases of ambiguous lesions on mpMRI, successfully identified csPCa and could potentially reduce unnecessary biopsies. The urinome-based collagen signature represents a promising liquid biopsy tool that requires prospective evaluation to improve the potential of this collagen-based approach to enhance diagnostic precision in PCa for risk stratification and guiding personalized interventions.

PATIENT SUMMARY

In our study, collagen-related alterations in tissue, and urine were able to predict the presence of clinically significant prostate cancer at primary diagnosis.

MDA-9/Syntenin in the tumor and microenvironment defines prostate cancer bone metastasis

Bone metastasis is a frequent and incurable consequence of advanced prostate cancer (PC). An interplay between disseminated tumor cells and heterogeneous bone resident cells in the metastatic niche initiates this process. Melanoma differentiation associated gene-9 (mda-9/Syntenin/syndecan binding protein) is a prometastatic gene expressed in multiple organs, including bone marrow-derived mesenchymal stromal cells (BM-MSCs), under both physiological and pathological conditions. We demonstrate that PDGF-AA secreted by tumor cells induces CXCL5 expression in BM-MSCs by suppressing MDA-9-dependent YAP/MST signaling. CXCL5-derived tumor cell proliferation and immune suppression are consequences of the MDA-9/CXCL5 signaling axis, promoting PC disease progression. mda-9 knockout tumor cells express less PDGF-AA and do not develop bone metastases. Our data document a previously undefined role of MDA-9/Syntenin in the tumor and microenvironment in regulating PC bone metastasis. This study provides a framework for translational strategies to ameliorate health complications and morbidity associated with advanced PC.

Cancer Stem Cells and Prostate Cancer: A Narrative Review

Cancer stem cells (CSCs) are a small and elusive subpopulation of self-renewing cancer cells with the remarkable ability to initiate, propagate, and spread malignant disease. In the past years, several authors have focused on the possible role of CSCs in PCa development and progression. PCa CSCs typically originate from a luminal prostate cell. Three main pathways are involved in the CSC development, including the Wnt, Sonic Hedgehog, and Notch signaling pathways. Studies have observed an important role for epithelial mesenchymal transition in this process as well as for some specific miRNA. These studies led to the development of studies targeting these specific pathways to improve the management of PCa development and progression. CSCs in prostate cancer represent an actual and promising field of research.

SLC14A1 is a new biomarker in renal cancer

BACKGROUND

Renal cancer is one of the common malignant tumors of the urinary tract, prone to distant metastasis and drug resistance, with a poor clinical prognosis. SLC14A1 belongs to the solute transporter family, which plays a role in urinary concentration and urea nitrogen recycling in the renal, and is closely associated with the development of a variety of tumors.

METHODS

Transcription data for renal clear cell carcinoma (KIRC) were obtained from the public databases Gene Expression Omnibus database (GEO) and The Cancer Genome Atlas (TCGA), and we investigated the differences in SLC14A1 expression in cancerous and normal tissues of renal cancer, its correlation with the clinicopathological features of renal cancer patients. Then, we verified the expression levels of SLC14A1 in renal cancer tissues and their Paracancerous tissues using RT-PCR, Western-blotting and immunohistochemistry. Finally, we used renal endothelial cell line HEK-293 and renal cancer cell lines 786-O and ACHN to explore the effects of SLC14A1 on the biological behaviors of renal cancer cell proliferation, invasion and metastasis using EDU, MTT proliferation assay, Transwell invasion assay and scratch healing assay.

RESULTS

SLC14A1 was lowly expressed in renal cancer tissues and this was further validated by RT-PCR, Western blotting, and immunohistochemistry in our clinical samples. Analysis of KIRC single-cell data suggested that SLC14A1 was mainly expressed in endothelial cells. Survival analysis showed that low levels of SLC14A1 expression were associated with a better clinical prognosis. In biological behavioral studies, we found that upregulation of SLC14A1 expression levels inhibited the proliferation, invasion, and metastatic ability of renal cancer cells.

CONCLUSION

SLC14A1 plays an important role in the progression of renal cancer and has the potential to become a new biomarker for renal cancer.

Role of Basic Fibroblast Growth Factor in Cancer: Biological Activity, Targeted Therapies, and Prognostic Value

Cancer is the leading cause of death worldwide; thus, it is necessary to find successful strategies. Several growth factors, such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF, FGF2), and transforming growth factor beta (TGF-β), are involved in the main processes that fuel tumor growth, i.e., cell proliferation, angiogenesis, and metastasis, by activating important signaling pathways, including PLC-γ/PI3/Ca2+ signaling, leading to PKC activation. Here, we focused on bFGF, which, when secreted by tumor cells, mediates several signal transductions and plays an influential role in tumor cells and in the development of chemoresistance. The biological mechanism of bFGF is shown by its interaction with its four receptor subtypes: fibroblast growth factor receptor (FGFR) 1, FGFR2, FGFR3, and FGFR4. The bFGF–FGFR interaction stimulates tumor cell proliferation and invasion, resulting in an upregulation of pro-inflammatory and anti-apoptotic tumor cell proteins. Considering the involvement of the bFGF/FGFR axis in oncogenesis, preclinical and clinical studies have been conducted to develop new therapeutic strategies, alone and/or in combination, aimed at intervening on the bFGF/FGFR axis. Therefore, this review aimed to comprehensively examine the biological mechanisms underlying bFGF in the tumor microenvironment, the different anticancer therapies currently available that target the FGFRs, and the prognostic value of bFGF.

Liver Microenvironment Response to Prostate Cancer Metastasis and Hormonal Therapy

Prostate cancer-associated deaths arise from disease progression and metastasis. Metastasis to the liver is associated with the worst clinical outcomes for prostate cancer patients, and these metastatic tumors can be particularly resistant to the currently widely used chemotherapy and hormonal therapies, such as anti-androgens which block androgen synthesis or directly target the androgen receptor. The incidence of liver metastases is reportedly increasing, with a potential correlation with use of anti-androgen therapies. A key player in prostate cancer progression and therapeutic response is the microenvironment of the tumor(s). This is a dynamic and adaptive collection of cells and proteins, which impart signals and stimuli that can alter biological processes within prostate cancer cells. Investigation in the prostate primary site has demonstrated that cells of the microenvironment are also responsive to hormones and hormonal therapies. In this review, we collate information about what happens when cancer moves to the liver: the types of prostate cancer cells that metastasize there, the response of resident mesenchymal cells of the liver, and how the interactions between the cancer cells and the microenvironment may be altered by hormonal therapy.

A Nomogram for Predicting Prostate Cancer with Lymph Node Involvement in Robot-Assisted Radical Prostatectomy Era: A Retrospective Multicenter Cohort Study in Japan (The MSUG94 Group)

Background: To create a nomogram for predicting prostate cancer (PCa) with lymph node involvement (LNI) in the robot-assisted radical prostatectomy (RARP) era. Methods: A retrospective multicenter cohort study was conducted on 3195 patients with PCa who underwent RARP at nine institutions in Japan between September 2012 and August 2021. A multivariable logistic regression model was used to identify factors strongly associated with LNI. The Bootstrap-area under the curve (AUC) was calculated to assess the internal validity of the prediction model. Results: A total of 1855 patients were enrolled in this study. Overall, 93 patients (5.0%) had LNI. On multivariable analyses, initial prostate-specific antigen, number of cancer-positive and-negative biopsy cores, biopsy Gleason grade, and clinical T stage were independent predictors of PCa with LNI. The nomogram predicting PCa with LNI has been demonstrated (AUC 84%). Using a nomogram cut-off of 6%, 492 of 1855 patients (26.5%) would avoid unnecessary pelvic lymph node dissection, and PCa with LNI would be missed in two patients (0.1%). The sensitivity, specificity, and negative predictive values associated with a cutoff of 6% were 74%, 80%, and 99.6%, respectively. Conclusions: We developed a clinically applicable nomogram for predicting the probability of patients with PCa with LNI.

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.

Prostate Cancer Stem Cells: Clinical Aspects and Targeted Therapies

Despite decades of research and successful improvements in diagnosis and therapy, prostate cancer (PC) remains a major challenge. In recent years, it has become clear that PC stem cells (PCSCs) are the driving force in tumorigenesis, relapse, metastasis, and therapeutic resistance of PC. In this minireview, we discuss the impact of PCSCs in the clinical practice. Moreover, new therapeutic approaches to combat PCSCs are presented with the aim to achieve an improved outcome for patients with PC.

Fresh tissue procurement and preparation for multicompartment and multimodal analysis of the prostate tumor microenvironment

BACKGROUND

Prostatic cancers include a diverse microenvironment of tumor cells, cancer-associated fibroblasts, and immune components. This tumor microenvironment (TME) is a known driving force of tumor survival after treatment, but the standard-of-care tissue freezing or fixation in pathology practice limit the use of available approaches/tools to study the TME's functionality in tumor resistance. Thus, there is a need for approaches that satisfy both clinical and laboratory endpoints for TME study. Here we present methods for clinical case identification, tissue processing, and analytical workflow that are compatible with standard histopathology while enabling molecular and functional interrogation of prostate TME components.

METHODS

We first performed a small retrospective review to identify cases where submission of alternate prostate tissue slices and a parallel live tissue processing protocol complement traditional histopathology and enable viable multicompartment analysis of the TME. Then, we tested its compatibility with commonly employed methods to study the microenvironment including quantification of components both in situ and after tissue dissociation. We also evaluated tissue digestion conditions and cell isolation techniques to aid various molecular and functional endpoints.

RESULTS

We identified Gleason Grade Group 3+ clinical cases where tumor volume was sufficient to allow slicing of unfixed tissue and distribution of alternating tissue slices to standard-of-care histopathology and viable multi-modal TME analyses. No single method was found that preserved cellular sub-types for all downstream readouts; instead, tissues were further divided so techniques could be catered to each endpoint. For instance, we show that incorporating the protease dispase into tissue dissociation improves viability for culture and functional analyses but hinders immune cell analysis by flow cytometry. We also found that flow activated cell sorting provides highly pure cell populations for quantitative reverse-transcription polymerase chain reaction and RNA-seq while isolation using antibody-labeled paramagnetic particles facilitated functional coculture experiments.

CONCLUSIONS

The identification of candidate cases and use of these techniques enable translational research and the development of molecular and functional assays to facilitate prostate TME study without compromising standard-of-care histopathological diagnosis. This allows bridging clinical histopathology and further interrogation of the prostate TME and promises to advance our understanding of tumor biology and unveil new predictive and prognostic markers of prostate cancer progression.

The cancer-inhibitory effects of proliferating tumor-residing fibroblasts

Initiation, local progression, and metastasis of cancer are associated with specific morphological, molecular, and functional changes in the extracellular matrix and the fibroblasts within the tumor microenvironment (TME). In the early stages of tumor development, fibroblasts are an obstacle that cancer cells must surpass or nullify to progress. Thus, in early tumor progression, specific signaling from cancer cells activates bio-pathways, which abolish the innate anticancer properties of fibroblasts and convert a high proportion of them to tumor-promoting cancer-associated fibroblasts (CAFs). Following this initial event, a wide spectrum of gene expression changes gradually leads to the development of a stromal fibroblast population with complex heterogeneity, creating fibroblast subtypes with characteristic profiles, which may alternate between being tumor-promotive and tumor-suppressive, topologically and chronologically in the TME. These fibroblast subtypes form the tumor's histological landscape including areas of cancer growth, inflammation, angiogenesis, invasion fronts, proliferating and non-proliferating fibroblasts, cancer-cell apoptosis, fibroblast apoptosis, and necrosis. These features reflect general deregulation of tissue homeostasis within the TME. This review discusses fundamental and current knowledge that has established the existence of anticancer fibroblasts within the various interacting elements of the TME. It is proposed that the maintenance of fibroblast proliferation is an essential parameter for the activation of their anticancer capacity, similar to that by which normal fibroblasts would be activated in wound repair, thus maintaining tissue homeostasis. Encouragement of research in this direction may render new means of cancer therapy and a greater understanding of tumor progression.

A Humanized Monoclonal Antibody Targeting Extracellular Nicotinamide Phosphoribosyltransferase Prevents Aggressive Prostate Cancer Progression

Prostate cancer (PCa) is the major cause of cancer-related death in males; however, effective treatments to prevent aggressive progression remain an unmet need. We have previously demonstrated that secreted extracellular nicotinamide phosphoribosyltransferase (eNAMPT) is a multifunctional innate immunity regulator that promotes PCa invasion. In the current study, we further investigate the therapeutic effects of an eNAMPT-neutralizing humanized monoclonal antibody (ALT-100 mAb) in preclinical PCa orthotopic xenograft models. We utilized human aggressive PCa cells (DU145 or PC3) for prostate implantation in SCID mice receiving weekly intraperitoneal injections of either ALT-100 mAb or IgG/PBS (control) for 12 weeks. Prostatic tumors and solid organs were examined for tumor growth, invasion, and metastasis and for biochemical and immunohistochemistry evidence of NFκB activation. ALT-100 mAb treatment significantly improved overall survival of SCID mice implanted with human PCa orthotopic prostate xenografts while inducing tumor necrosis, decreasing PCa proliferation and reducing local invasion and distal metastases. The ALT-100 mAb inhibits NFκB phosphorylation and signaling in PCa cells both in vitro and in vivo. This study demonstrates that eNAMPT neutralization effectively prevents human PCa aggressive progression in preclinical models, indicating its high potential to directly address the unmet need for an effective targeted therapy for patients with aggressive PCa.

Genetic Contributions to Prostate Cancer Disparities in Men of West African Descent

Prostate cancer (PCa) is the second most frequently diagnosed malignancy and the second leading cause of death in men worldwide, after adjusting for age. According to the International Agency for Research on Cancer, continents such as North America and Europe report higher incidence of PCa; however, mortality rates are highest among men of African ancestry in the western, southern, and central regions of Africa and the Caribbean. The American Cancer Society reports, African Americans (AAs), in the United States, have a 1.7 increased incidence and 2.4 times higher mortality rate, compared to European American's (EAs). Hence, early population history in west Africa and the subsequent African Diaspora may play an important role in understanding the global disproportionate burden of PCa shared among Africans and other men of African descent. Nonetheless, disparities involved in diagnosis, treatment, and survival of PCa patients has also been correlated to socioeconomic status, education and access to healthcare. Although recent studies suggest equal PCa treatments yield equal outcomes among patients, data illuminates an unsettling reality of disparities in treatment and care in both, developed and developing countries, especially for men of African descent. Yet, even after adjusting for the effects of the aforementioned factors; racial disparities in mortality rates remain significant. This suggests that molecular and genomic factors may account for much of PCa disparities.

An RNA-Seq-Based Framework for Characterizing Canine Prostate Cancer and Prioritizing Clinically Relevant Biomarker Candidate Genes

Prostate cancer (PCa) in dogs is a highly malignant disease akin to its human counterpart. In contrast to the situation in humans, multi-gene approaches facilitating risk stratification of canine PCa are barely established. The aims of this study were the characterization of the transcriptional landscape of canine PCa and the identification of diagnostic, prognostic and/or therapeutic biomarkers through a multi-step screening approach. RNA-Sequencing of ten malignant tissues and fine-needle aspirations (FNA), and 14 nonmalignant tissues and FNAs was performed to find differentially expressed genes (DEGs) and deregulated pathways. The 4098 observed DEGs were involved in 49 pathways. These 49 pathways could be grouped into five superpathways summarizing the hallmarks of canine PCa: (i) inflammatory response and cytokines; (ii) regulation of the immune system and cell death; (iii) cell surface and PI3K signaling; (iv) cell cycle; and (v) phagosome and autophagy. Among the highly deregulated, moderately to strongly expressed DEGs that were members of one or more superpathways, 169 DEGs were listed in relevant databases and/or the literature and included members of the PCa pathway, oncogenes, prostate-specific genes, and druggable genes. These genes are novel and promising candidate diagnostic, prognostic and/or therapeutic canine PCa biomarkers.

Current Treatment Modalities Targeting Tumor Microenvironment in Castration-Resistant Prostate Cancer

Prostate cancer (PCa) is responsible for significant cancer-related morbidity and mortality following local treatment failure in men. The initial stages of PCa are typically managed with a combination of surgical resection and/or androgen deprivation therapy (ADT). Unfortunately, a significant proportion of PCa continues to progress despite being at castrate levels of testosterone (<50 ng/dl), at which point it is coined castration-resistant prostate cancer (CRPC). In recent years, many novel therapeutics and drug combinations have been created for CRPC patients. These include immune checkpoint inhibitors, chemokine receptor antagonists, steroidogenic enzyme inhibition, and novel tyrosine kinase inhibitors as well as combinations of drugs. The selection of the most appropriate therapy depends on several factors like stage of the disease, age of the patient, metastasis, functional status, and response towards previous therapies. Here, we review the current state of the literature regarding treatment modalities, focusing on the treatment recommendations per the American Urological Association (AUA), recent clinical trials, and their limitations. An accurate and reliable overview of the strengths and limitations of PCa therapeutics could also allow personalized therapeutic interventions against PCa.

Natural Product-Based Studies for the Management of Castration-Resistant Prostate Cancer: Computational to Clinical Studies

Background: With prostate cancer being the fifth-greatest cause of cancer mortality in 2020, there is a dire need to expand the available treatment options. Castration-resistant prostate cancer (CRPC) progresses despite androgen depletion therapy. The mechanisms of resistance are yet to be fully discovered. However, it is hypothesized that androgens depletion enables androgen-independent cells to proliferate and recolonize the tumor. Objectives: Natural bioactive compounds from edible plants and herbal remedies might potentially address this need. This review compiles the available cheminformatics-based studies and the translational studies regarding the use of natural products to manage CRPC. Methods: PubMed and Google Scholar searches for preclinical studies were performed, while ClinicalTrials.gov and PubMed were searched for clinical updates. Studies that were not in English and not available as full text were excluded. The period of literature covered was from 1985 to the present. Results and Conclusion: Our analysis suggested that natural compounds exert beneficial effects due to their broad-spectrum molecular disease-associated targets. In vitro and in vivo studies revealed several bioactive compounds, including rutaecarpine, berberine, curcumin, other flavonoids, pentacyclic triterpenoids, and steroid-based phytochemicals. Molecular modeling tools, including machine and deep learning, have made the analysis more comprehensive. Preclinical and clinical studies on resveratrol, soy isoflavone, lycopene, quercetin, and gossypol have further validated the translational potential of the natural products in the management of prostate cancer.

Racial disparity in prostate cancer in the African American population with actionable ideas and novel immunotherapies

Background

African Americans (AAs) in the United States are known to have a higher incidence and mortality for Prostate Cancer (PCa). The drivers of this epidemiological disparity are multifactorial, including socioeconomic factors leading to lifestyle and dietary issues, healthcare access problems, and potentially tumor biology.

Recent findings

Although recent evidence suggests once access is equal, AA men have equal outcomes to Caucasian American (CA) men, differences in PCa incidence remain, and there is much to do to reverse disparities in mortality across the USA. A deeper understanding of these issues, both at the clinical and molecular level, can facilitate improved outcomes in the AA population. This review first discusses PCa oncogenesis in the context of its diverse hallmarks before benchmarking key molecular and genomic differences for PCa in AA men that have emerged in the recent literature. Studies have emphasized the importance of tumor microenvironment that contributes to both the unequal cancer burden and differences in clinical outcome between the races. Management of comorbidities like obesity, hypertension, and diabetes will provide an essential means of reducing prostate cancer incidence in AA men. Although requiring further AA specific research, several new treatment strategies such as immune checkpoint inhibitors used in combination PARP inhibitors and other emerging vaccines, including Sipuleucel‐T, have demonstrated some proven efficacy.

Conclusion

Genomic profiling to integrate clinical and genomic data for diagnosis, prognosis, and treatment will allow physicians to plan a “Precision Medicine” approach to AA men. There is a pressing need for further research for risk stratification, which may allow early identification of AA men with higher risk disease based on their unique clinical, genomic, and immunological profiles, which can then be mapped to appropriate clinical trials. Treatment options are outlined, with a concise description of recent work in AA specific populations, detailing several targeted therapies, including immunotherapy. Also, a summary of current clinical trials involving AA men is presented, and it is important that policies are adopted to ensure that AA men are actively recruited. Although it is encouraging that many of these explore the lifestyle and educational initiatives and therapeutic interventions, there is much still work to be done to reduce incidence and mortality in AA men and equalize current racial disparities.

Prostate cancer

Prostate cancer is a complex disease that affects millions of men globally, predominantly in high human development index regions. Patients with localized disease at a low to intermediate risk of recurrence generally have a favourable outcome of 99% overall survival for 10 years if the disease is detected and treated at an early stage. Key genetic alterations include fusions of TMPRSS2 with ETS family genes, amplification of the MYC oncogene, deletion and/or mutation of PTEN and TP53 and, in advanced disease, amplification and/or mutation of the androgen receptor (AR). Prostate cancer is usually diagnosed by prostate biopsy prompted by a blood test to measure prostate-specific antigen levels and/or digital rectal examination. Treatment for localized disease includes active surveillance, radical prostatectomy or ablative radiotherapy as curative approaches. Men whose disease relapses after prostatectomy are treated with salvage radiotherapy and/or androgen deprivation therapy (ADT) for local relapse, or with ADT combined with chemotherapy or novel androgen signalling-targeted agents for systemic relapse. Advanced prostate cancer often progresses despite androgen ablation and is then considered castration-resistant and incurable. Current treatment options include AR-targeted agents, chemotherapy, radionuclides and the poly(ADP-ribose) inhibitor olaparib. Current research aims to improve prostate cancer detection, management and outcomes, including understanding the fundamental biology at all stages of the disease.

Prostate cancer

Prostate cancer is a complex disease that affects millions of men globally, predominantly in high human development index regions. Patients with localized disease at a low to intermediate risk of recurrence generally have a favourable outcome of 99% overall survival for 10 years if the disease is detected and treated at an early stage. Key genetic alterations include fusions of TMPRSS2 with ETS family genes, amplification of the MYC oncogene, deletion and/or mutation of PTEN and TP53 and, in advanced disease, amplification and/or mutation of the androgen receptor (AR). Prostate cancer is usually diagnosed by prostate biopsy prompted by a blood test to measure prostate-specific antigen levels and/or digital rectal examination. Treatment for localized disease includes active surveillance, radical prostatectomy or ablative radiotherapy as curative approaches. Men whose disease relapses after prostatectomy are treated with salvage radiotherapy and/or androgen deprivation therapy (ADT) for local relapse, or with ADT combined with chemotherapy or novel androgen signalling-targeted agents for systemic relapse. Advanced prostate cancer often progresses despite androgen ablation and is then considered castration-resistant and incurable. Current treatment options include AR-targeted agents, chemotherapy, radionuclides and the poly(ADP-ribose) inhibitor olaparib. Current research aims to improve prostate cancer detection, management and outcomes, including understanding the fundamental biology at all stages of the disease.

Stroma Transcriptomic and Proteomic Profile of Prostate Cancer Metastasis Xenograft Models Reveals Prognostic Value of Stroma Signatures

Resistance acquisition to androgen deprivation treatment and metastasis progression are a major clinical issue associated with prostate cancer (PCa). The role of stroma during disease progression is insufficiently defined. Using transcriptomic and proteomic analyses on differentially aggressive patient-derived xenografts (PDXs), we investigated whether PCa tumors predispose their microenvironment (stroma) to a metastatic gene expression pattern. RNA sequencing was performed on the PCa PDXs BM18 (castration-sensitive) and LAPC9 (castration-resistant), representing different disease stages. Using organism-specific reference databases, the human-specific transcriptome (tumor) was identified and separated from the mouse-specific transcriptome (stroma). To identify proteomic changes in the tumor (human) versus the stroma (mouse), we performed human/mouse cell separation and subjected protein lysates to quantitative Tandem Mass Tag labeling and mass spectrometry. Tenascin C (TNC) was among the most abundant stromal genes, modulated by androgen levels in vivo and highly expressed in castration-resistant LAPC9 PDX. The tissue microarray of primary PCa samples (n = 210) showed that TNC is a negative prognostic marker of the clinical progression to recurrence or metastasis. Stroma markers of osteoblastic PCa bone metastases seven-up signature were induced in the stroma by the host organism in metastatic xenografts, indicating conserved mechanisms of tumor cells to induce a stromal premetastatic signature. A 50-gene list stroma signature was identified based on androgen-dependent responses, which shows a linear association with the Gleason score, metastasis progression and progression-free survival. Our data show that metastatic PCa PDXs, which differ in androgen sensitivity, trigger differential stroma responses, which show the metastasis risk stratification and prognostic biomarker potential.

Androgen receptor signalling in macrophages promotes TREM-1-mediated prostate cancer cell line migration and invasion

The androgen receptor (AR) is the master regulator of prostate cancer (PCa) development, and inhibition of AR signalling is the most effective PCa treatment. AR is expressed in PCa cells and also in the PCa-associated stroma, including infiltrating macrophages. Macrophages have a decisive function in PCa initiation and progression, but the role of AR in macrophages remains largely unexplored. Here, we show that AR signalling in the macrophage-like THP-1 cell line supports PCa cell line migration and invasion in culture via increased Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) signalling and expression of its downstream cytokines. Moreover, AR signalling in THP-1 and monocyte-derived macrophages upregulates IL-10 and markers of tissue residency. In conclusion, our data suggest that AR signalling in macrophages may support PCa invasiveness, and blocking this process may constitute one mechanism of anti-androgen therapy.

Anti-androgen therapy inhibits prostate cancer (PC) progression, and is thought to act directly on cancer cells. Here the authors show that androgen receptor is expressed on normal and PC-associated macrophages, and its stimulation alters macrophage secretome to promote migration of cultured PC cell lines.

Ablation of sensory nerves favours melanoma progression

The tumour mass is composed not only of heterogeneous neoplastic cells, but also a variety of other components that may affect cancer cells behaviour. The lack of detailed knowledge about all the constituents of the tumour microenvironment restricts the design of effective treatments. Nerves have been reported to contribute to the growth and maintenance of numerous tissues. The effects of sensory innervations on tumour growth remain unclear. Here, by using state-of-the-art techniques, including Cre/loxP technologies, confocal microscopy, in vivo-tracing and chemical denervation, we revealed the presence of sensory nerves infiltrating within the melanoma microenvironment, and affecting cancer progression. Strikingly, melanoma growth in vivo was accelerated following genetic ablation or chemical denervation of sensory nerves. In humans, a retrospective analysis of melanoma patients revealed that increased expression of genes related to sensory nerves in tumours was associated with better clinical outcomes. These findings suggest that sensory innervations counteract melanoma progression. The emerging knowledge from this research provides a novel target in the tumour microenvironment for therapeutic benefit in cancer patients.

The New Era of Cancer Immunotherapy: Targeting Myeloid-Derived Suppressor Cells to Overcome Immune Evasion

Suppression of antitumor immune responses is one of the main mechanisms by which tumor cells escape from destruction by the immune system. Myeloid-derived suppressor cells (MDSCs) represent the main immunosuppressive cells present in the tumor microenvironment (TME) that sustain cancer progression. MDSCs are a heterogeneous group of immature myeloid cells with a potent activity against T-cell. Studies in mice have demonstrated that MDSCs accumulate in several types of cancer where they promote invasion, angiogenesis, and metastasis formation and inhibit antitumor immunity. In addition, different clinical studies have shown that MDSCs levels in the peripheral blood of cancer patients correlates with tumor burden, stage and with poor prognosis in multiple malignancies. Thus, MDSCs are the major obstacle to many cancer immunotherapies and their targeting may be a beneficial strategy for improvement the efficiency of immunotherapeutic interventions. However, the great heterogeneity of these cells makes their identification in human cancer very challenging. Since both the phenotype and mechanisms of action of MDSCs appear to be tumor-dependent, it is important to accurately characterized the precise MDSC subsets that have clinical relevance in each tumor environment to more efficiently target them. In this review we summarize the phenotype and the suppressive mechanisms of MDSCs populations expanded within different tumor contexts. Further, we discuss about their clinical relevance for cancer diagnosis and therapy.

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.

Recapitulation of prostate tissue cell type-specific transcriptomes by an in vivo primary prostate tissue xenograft model

Studies of the normal functions and diseases of the prostate request in vivo models that maintain the tissue architecture and the multiple-cell type compartments of human origin in order to recapitulate reliably the interactions of different cell types. Cell type-specific transcriptomes are critical to reveal the roles of each cell type in the functions and diseases of the prostate. A primary prostate tissue xenograft model was developed using fresh human prostate tissue specimens transplanted onto male mice that were castrated surgically and implanted with a device to maintain circulating testosterone levels comparable to adult human males. Endothelial cells and epithelial cells were isolated from 7 fresh human prostate tissue specimens and from primary tissue xenografts established from 9 fresh human prostate tissue specimens, using antibody-conjugated magnetic beads specific to human CD31 and human EpCAM, respectively. Transcriptomes of endothelial, epithelial and stromal cell fractions were obtained using RNA-Seq. Global and function-specific gene expression profiles were compared in inter-cell type and inter-tissue type manners. Gene expression profiles in the individual cell types isolated from xenografts were similar to those of cells isolated from fresh tissue, demonstrating the value of the primary tissue xenograft model for studies of the inter-relationships between prostatic cell types and the role of such inter-relationships in organ development, disease progression, and response to drug treatments.

ILC2s: New Actors in Tumor Immunity

Innate lymphoid cells (ILCs) represent the most recently identified family of innate lymphocytes that act as first responders, maintaining tissue homeostasis and protecting epithelial barriers. In the last few years, group 2 ILCs (ILC2s) have emerged as key regulators in several immunological processes such as asthma and allergy. Whilst ILC2s are currently being evaluated as novel targets for immunotherapy in these diseases, their involvement in tumor immunity has only recently begun to be deciphered. Here, we provide a comprehensive overview of the pleiotropic roles of ILC2s in different tumor settings. Furthermore, we discuss how different therapeutic approaches targeting ILC2s could improve the efficacy of current tumor immunotherapies.

Network-based analysis of prostate cancer cell lines reveals novel marker gene candidates associated with radioresistance and patient relapse

Radiation therapy is an important and effective treatment option for prostate cancer, but high-risk patients are prone to relapse due to radioresistance of cancer cells. Molecular mechanisms that contribute to radioresistance are not fully understood. Novel computational strategies are needed to identify radioresistance driver genes from hundreds of gene copy number alterations. We developed a network-based approach based on lasso regression in combination with network propagation for the analysis of prostate cancer cell lines with acquired radioresistance to identify clinically relevant marker genes associated with radioresistance in prostate cancer patients. We analyzed established radioresistant cell lines of the prostate cancer cell lines DU145 and LNCaP and compared their gene copy number and expression profiles to their radiosensitive parental cells. We found that radioresistant DU145 showed much more gene copy number alterations than LNCaP and their gene expression profiles were highly cell line specific. We learned a genome-wide prostate cancer-specific gene regulatory network and quantified impacts of differentially expressed genes with directly underlying copy number alterations on known radioresistance marker genes. This revealed several potential driver candidates involved in the regulation of cancer-relevant processes. Importantly, we found that ten driver candidates from DU145 (ADAMTS9, AKR1B10, CXXC5, FST, FOXL1, GRPR, ITGA2, SOX17, STARD4, VGF) and four from LNCaP (FHL5, LYPLAL1, PAK7, TDRD6) were able to distinguish irradiated prostate cancer patients into early and late relapse groups. Moreover, in-depth in vitro validations for VGF (Neurosecretory protein VGF) showed that siRNA-mediated gene silencing increased the radiosensitivity of DU145 and LNCaP cells. Our computational approach enabled to predict novel radioresistance driver gene candidates. Additional preclinical and clinical studies are required to further validate the role of VGF and other candidate genes as potential biomarkers for the prediction of radiotherapy responses and as potential targets for radiosensitization of prostate cancer.

Prostate cancer cell lines represent an important model system to characterize molecular alterations that contribute to radioresistance, but irradiation can cause deletions and amplifications of DNA segments that affect hundreds of genes. This in combination with the small number of cell lines that are usually considered does not allow a straight-forward identification of driver genes by standard statistical methods. Therefore, we developed a network-based approach to analyze gene copy number and expression profiles of such cell lines enabling to identify potential driver genes associated with radioresistance of prostate cancer. We used lasso regression in combination with a significance test for lasso to learn a genome-wide prostate cancer-specific gene regulatory network. We used this network for network flow computations to determine impacts of gene copy number alterations on known radioresistance marker genes. Mapping to prostate cancer samples and additional filtering allowed us to identify 14 driver gene candidates that distinguished irradiated prostate cancer patients into early and late relapse groups. In-depth literature analysis and wet-lab validations suggest that our method can predict novel radioresistance driver genes. Additional preclinical and clinical studies are required to further validate these genes for the prediction of radiotherapy responses and as potential targets to radiosensitize prostate cancer.

Non-nuclear AR Signaling in Prostate Cancer

Despite the key role played by androgen receptor (AR) in tumor cell aggressiveness and prostate cancer (PCa) progression, its function in the tumor microenvironment (TME) is still controversial. Increasing studies highlight the crucial role played by TME modulation in treatment outcome and tumor cell spreading. In this context, targeting specific constituents of the TME could be considered an alternative approach to classic treatments directed against cancer cells. Currently, androgen deprivation therapy (ADT) is a routinely adopted strategy in the management of PCa, with initial success, and consecutive fail. A possible justification to this is the fact that ADT aims to target all the transcription/translation-related activities of AR, which are typical of tumor epithelial cells. Less is still known about side effects of ADT on TME. Cancer Associated Fibroblasts (CAFs), for example, express a classic AR, mostly confined in the extra-nuclear portion of the cell. In CAFs ADT exerts a plethora of non-transcriptional effects, depending by the protein partner linked to AR, leading to cell migration, proliferation, and differentiation. In recent years, substantial progress in the structure-function relationships of AR, identification of its binding partners and function of protein complexes including AR have improved our knowledge of its signaling axis. Important AR non-genomic effects and lots of its cytoplasmatic binding partners have been described, pointing out a fine control of AR non-genomic pathways. Accordingly, new AR inhibitors have been designed and are currently under investigation. Prompt development of new approaches to target AR or block recruitment of its signaling effectors, or co-activators, is urgently needed. The present review takes an in-depth look at current literature, furnishing an exhaustive state-of-the-art overview of the non-genomic role of AR in PCa, with particular emphasis on its involvement in TME biology.

CXCL1-LCN2 paracrine axis promotes progression of prostate cancer via the Src activation and epithelial-mesenchymal transition

BACKGROUND

Mechanisms driving the progression of castration-resistant prostate cancer are believed to relate substantially to the tumor microenvironment. However, the cross-talks between tumor epithelial cell, stromal cells, and immune cells are yet to be fully elucidated. The present study aims to determine the role of chemokine and neutrophil derived cytokine paracrine axis in mediating the interaction between tumor cells, stromal myofibroblasts, and neutrophils in the tumor microenvironment of prostate cancer.

METHODS

To identify myofibroblasts and neutrophil derived specific proteins affecting progression of prostate cancer, bioinformatics analyses were firstly performed in independent human prostate cancer gene expression data sets from the GEO data bank. Expression of stromal myofibroblasts secretory chemokine CXCL1 and neutrophil derived cytokine LCN2 was evaluated in prostate tissues via immunohistochemistry assay. We further investigated the effect of CXCL1 and LCN2 on prostate cancer using in vivo and in vitro models, and explored the underlying signal transduction pathways.

RESULTS

A CXCL1-LCN2 paracrine network was confirmed in prostate cancer tissue samples, which was correlated with the biochemical recurrence of prostate cancer. Of note, CXCL1-LCN2 axis activates Src signaling, triggers the epithelial-mesenchymal transition (EMT), consequently promotes the migration of prostate cancer cells, leading to enhanced tumor metastasis.

CONCLUSIONS

Our findings may provide enhanced insight into the interactions of carcinoma-stromal cells and immune cells linked to prostate cancer progression, wherein CXCL1-LCN2 axis is a key contributor to prostate cancer cells migration. These data indicate tumor microenvironment and Src signaling pathway may be potential therapeutic targets of prostate cancer treatment.

Utilizing precision medicine to modulate the prostate tumor microenvironment and enhance immunotherapy

The last two decades of cancer research have seen two major advancements in our ability to treat cancer: precision medicine and immunotherapy. While these approaches have shown striking anticancer efficacy in numerous malignancies, they have not shown similar success and applicability in advanced prostate cancer patients. The fields of precision medicine and immunotherapy have come to realize that targeted therapies are capable of not only inhibiting tumor cell growth, but also promoting antitumor immunity by modulating the tumor microenvironment. Here we examine how personalized medicine can be used to target the tumor immune microenvironment in prostate cancer, with the goal of enhancing clinical responses to immunotherapy.

Prostate tumor neuroendocrine differentiation via EMT: The road less traveled

The long-standing challenge in the treatment of prostate cancer is to overcome therapeutic resistance during progression to lethal disease. Aberrant transforming-growth factor-β (TGF-β) signaling accelerates prostate tumor progression in a transgenic mouse model via effects on epithelial-mesenchymal transition (EMT), and neuroendocrine differentiation driving tumor progression to castration-resistant prostate cancer (CRPC). Neuroendocrine prostate cancer (NEPC) is highly aggressive exhibiting reactivation of developmental programs associated with EMT induction and stem cell-like characteristics. The androgen receptor (AR) is a critical driver of tumor progression as well as therapeutic response in patients with metastatic CRPC. The signaling interactions between the TGF-β mechanistic network and AR axis impact the EMT phenotypic conversions, and perturbation of epithelial homeostasis via EMT renders a critical venue for epithelial derived tumors to become invasive, acquire the neuroendocrine phenotype, and rapidly metastasize. Combinations of microtubule targeting taxane chemotherapy and androgen/AR targeting therapies have survival benefits in CRPC patients, but therapeutic resistance invariability develops, leading to mortality. Compelling evidence from our group recently demonstrated that chemotherapy (cabazitaxel, second line taxane chemotherapy), or TGF-β receptor signaling targeted therapy, caused reversion of EMT to mesenchymal-epithelial transition and tumor re-differentiation, in in vitro and in vivo prostate cancer models. In this review, we discuss the functional contribution of EMT dynamic changes to the development of the neuroendocrine phenotype-the newly characterized pathological feature of prostate tumors in the context of the tumor microenvironment-navigated cell lineage changes and the role of this neuroendocrine phenotype in metastatic progression and therapeutic resistance.

Defeating Cancers' Adaptive Defensive Strategies Using Thermal Therapies: Examining Cancer's Therapeutic Resistance, Ablative, and Computational Modeling Strategies as a means for Improving Therapeutic Outcome

BACKGROUND

Diverse thermal ablative therapies are currently in use for the treatment of cancer. Commonly applied with the intent to cure, these ablative therapies are providing promising success rates similar to and often exceeding "gold standard" approaches. Cancer-curing prospects may be enhanced by deeper understanding of thermal effects on cancer cells and the hosting tissue, including the molecular mechanisms of cancer cell mutations, which enable resistance to therapy. Furthermore, thermal ablative therapies may benefit from recent developments in computer hardware and computation tools for planning, monitoring, visualization, and education.

METHODS

Recent discoveries in cancer cell resistance to destruction by apoptosis, autophagy, and necrosis are now providing an understanding of the strategies used by cancer cells to avoid destruction by immunologic surveillance. Further, these discoveries are now providing insight into the success of the diverse types of ablative therapies utilized in the clinical arena today and into how they directly and indirectly overcome many of the cancers' defensive strategies. Additionally, the manner in which minimally invasive thermal therapy is enabled by imaging, which facilitates anatomical features reconstruction, insertion guidance of thermal probes, and strategic placement of thermal sensors, plays a critical role in the delivery of effective ablative treatment.

RESULTS

The thermal techniques discussed include radiofrequency, microwave, high-intensity focused ultrasound, laser, and cryosurgery. Also discussed is the development of thermal adjunctive therapies-the combination of drug and thermal treatments-which provide new and more effective combinatorial physical and molecular-based approaches for treating various cancers. Finally, advanced computational and planning tools are also discussed.

CONCLUSION

This review lays out the various molecular adaptive mechanisms-the hallmarks of cancer-responsible for therapeutic resistance, on one hand, and how various ablative therapies, including both heating- and freezing-based strategies, overcome many of cancer's defenses, on the other hand, thereby enhancing the potential for curative approaches for various cancers.

Alterations of tumor microenvironment by nitric oxide impedes castration-resistant prostate cancer growth

Immune targeted therapy of nitric oxide (NO) synthases are being considered as a potential frontline therapeutic to treat patients diagnosed with locally advanced and metastatic prostate cancer. However, the role of NO in castration-resistant prostate cancer (CRPC) is controversial because NO can increase in nitrosative stress while simultaneously possessing antiinflammatory properties. Accordingly, we tested the hypothesis that increased NO will lead to tumor suppression of CRPC through tumor microenvironment. S-nitrosoglutathione (GSNO), an NO donor, decreased the tumor burden in murine model of CRPC by targeting tumors in a cell nonautonomous manner. GSNO inhibited both the abundance of antiinflammatory (M2) macrophages and expression of pERK, indicating that tumor-associated macrophages activity is influenced by NO. Additionally, GSNO decreased IL-34, indicating suppression of tumor-associated macrophage differentiation. Cytokine profiling of CRPC tumor grafts exposed to GSNO revealed a significant decrease in expression of G-CSF and M-CSF compared with grafts not exposed to GSNO. We verified the durability of NO on CRPC tumor suppression by using secondary xenograft murine models. This study validates the significance of NO on inhibition of CRPC tumors through tumor microenvironment (TME). These findings may facilitate the development of previously unidentified NO-based therapy for CRPC.

Leinal polypeptide promotes NK cells to suppress PCa survival in vitro

As an important component in the innate immune system, natural killer (NK) cells have been demonstrated to be clinically associated with prostate cancer (PCa) progression and castration resistance. Therefore, the development of novel agents that may enhance the cytotoxicity of NK cells possesses promising therapeutic applications. In the present study, leinal polypeptide (LP) solution was supplemented into a co-culture system of NK and PCa cells, as it was previously demonstrated that LP are able to activate NK cells, which kill PCa cells based on an MTT cell viability assay. Mechanistic dissection demonstrated that LP enhanced androgen receptor degradation, which resulted in an upregulation of MHC class I polypeptide-related sequence A (MICA) and MICB. In turn, the induced expression of MICA and MICB was able to further trigger NK cell activation, forming a positive loop between NK cells and PCa cells in the presence of LP solution.

Exosomal miR-141-3p regulates osteoblast activity to promote the osteoblastic metastasis of prostate cancer

Exosomes from cancer cells, which contain microRNA and reach metastasis loci prior to cancer cells, stimulate the formation of a metastatic microenvironment. Previous studies have shown that exosomal miR-141-3p is associated with metastatic prostate cancer (PCa). However, the role and regulatory mechanism of miR-141-3p in the microenvironment of bone metastases require further study. In this study, we performed a series of experiments in vivo and in vitro to determine whether exosomal miR-141-3p from MDA PCa 2b cells regulates osteoblast activity to promote osteoblastic metastasis. We demonstrate that extracts obtained from cell culture supernatants contained exosomes and that miR-141-3p levels were significantly higher in MDA PCa 2b cell exosomes. Via confocal imaging, numerous MDA PCa 2b exosomes were observed to enter osteoblasts, and miR-141-3p was transferred to osteoblasts through MDA PCa 2b exosomes in vitro. Exosomal miR-141-3p from MDA PCa 2b promoted osteoblast activity and increased osteoprotegerin OPG expression. miR-141-3p suppressed the protein levels of the target gene DLC1, indicating its functional significance in activating the p38MAPK pathway. In animal experiments, exosomal miR-141-3p had bone-target specificity and promoted osteoblast activity. Mice injected with miR-141-3p-mimics exosomes developed apparent osteoblastic bone metastasis. Exosomal miR-141-3p from MDA PCa 2b cells promoted osteoblast activity and regulated the microenvironment of bone metastases, which plays an important role in the formation of bone metastases and osteogenesis damage in PCa. Clarifying the specific mechanism of bone metastasis will help generate new possibilities for the treatment of PCa.

In Vivo Hemin Conditioning Targets the Vascular and Immunologic Compartments and Restrains Prostate Tumor Development

Purpose: Conditioning strategies constitute a relatively unexplored and exciting opportunity to shape tumor fate by targeting the tumor microenvironment. In this study, we assessed how hemin, a pharmacologic inducer of heme oxygenase-1 (HO-1), has an impact on prostate cancer development in an in vivo conditioning model.Experimental Design: The stroma of C57BL/6 mice was conditioned by subcutaneous administration of hemin prior to TRAMP-C1 tumor challenge. Complementary in vitro and in vivo assays were performed to evaluate hemin effect on both angiogenesis and the immune response. To gain clinical insight, we used prostate cancer patient-derived samples in our studies to assess the expression of HO-1 and other relevant genes.Results: Conditioning resulted in increased tumor latency and decreased initial growth rate. Histologic analysis of tumors grown in conditioned mice revealed impaired vascularization. Hemin-treated human umbilical vein endothelial cells (HUVEC) exhibited decreased tubulogenesis in vitro only in the presence of TRAMP-C1-conditioned media. Subcutaneous hemin conditioning hindered tumor-associated neovascularization in an in vivo Matrigel plug assay. In addition, hemin boosted CD8⁺ T-cell proliferation and degranulation in vitro and antigen-specific cytotoxicity in vivo A significant systemic increase in CD8⁺ T-cell frequency was observed in preconditioned tumor-bearing mice. Tumors from hemin-conditioned mice showed reduced expression of galectin-1 (Gal-1), key modulator of tumor angiogenesis and immunity, evidencing persistent remodeling of the microenvironment. We also found a subset of prostate cancer patient-derived xenografts and prostate cancer patient samples with mild HO-1 and low Gal-1 expression levels.Conclusions: These results highlight a novel function of a human-used drug as a means of boosting the antitumor response. Clin Cancer Res; 23(17); 5135-48. ©2017 AACR.

Sialylation facilitates self-assembly of 3D multicellular prostaspheres by using cyclo-RGDfK(TPP) peptide

Background

Prostaspheres-based three dimensional (3D) culture models have provided insight into prostate cancer (PCa) biology, highlighting the importance of cell–cell interactions and the extracellular matrix (EMC) in the tumor microenvironment. Although these 3D classical spheroid platforms provide a significant advance over 2D models mimicking in vivo tumors, the limitations involve no control of assembly and structure with only limited spatial or glandular organization. Here, matrix-free prostaspheres from human metastatic prostate carcinoma PC3 and DU145 cell lines and their respective gemcitabine resistant (GemR) variants were generated by using cyclic Arg-Gly-Asp-D-Phe-Lys peptide modified with 4-carboxybutyl-triphenylphosphonium bromide (cyclo-RGDfK(TPP)).

Materials and methods

Microscopic imaging, immunocytochemistry (ICC), flow cytometry, sialidase, and WST-1 cell viability assays were used to evaluate the formation of multicellular tumor spheroid (MCTS), cell survival, morphologic changes, and expression levels of α2,6 and α2,3 sialic acid (SA) and E- and N-cadherin in DU145, PC3, and their GemR variants.

Results

By using the cyclo-RGDfK(TPP) peptide platform in a dose- and time-dependent manner, both DU145 and DU145GemR cells formed small MCTS. In contrast, PC3 and PC3GemR cells formed irregular multicellular aggregates at all concentrations of cyclo-RGDfK(TPP) peptide, even after 6 days of incubation. ICC and flow cytometry results revealed that DU145 cells expressed higher amounts of E-cadherin but lower N-cadherin compared with PC3 cells. By using Maackia amurensis (α2,3-SA-specific MAL-II) and Sambucus nigra (α2,6-SA specific SNA) lectin-based cytochemistry staining and flow cytometry, it was found that DU145 and DU145GemR cells expressed 5 times more α2,6-SA than α2,3-SA on the cell surface. PC3 cells expressed 4 times more α2,3-SA than α2,6-SA, and the PC3GemR cells showed 1.4 times higher α2,6-SA than α2,3-SA. MCTS volume was dose-dependently reduced following pretreatment with α2,6-SA-specific neuraminidase (Vibrio cholerae). Oseltamivir phosphate enhanced cell aggregation and compaction of 3D MCTS formed with PC3 cells.

Conclusion

The relative levels of specific sialoglycan structures on the cell surface correlate with the ability of PCa cells to form avascular multicellular prostaspheres.

Mechanisms of Therapeutic Resistance in Prostate Cancer

Prostate cancer is the second leading cause of cancer deaths in the USA. The challenge in managing castration-resistant prostate cancer (CRPC) stems not from the lack of therapeutic options but from the limited duration of clinical and survival benefit offered by treatments in this setting due to primary and acquired resistance. The remarkable molecular heterogeneity and tumor adaptability in advanced prostate cancer necessitate optimization of such treatment strategies. While the future of CRPC management will involve newer targeted therapies in deliberately biomarker-selected patients, interventions using current approaches may exhibit improved clinical benefit if employed in the context of optimal sequencing and combinations. This review outlines our current understanding of mechanisms of therapeutic resistance in progression to and after the development of castration resistance, highlighting targetable and reversible mechanisms of resistance.

Collagen Extracted from Persian Gulf Squid Exhibits Anti-Cytotoxic Properties on Apple Pectic Treated Cells: Assessment in an In Vitro Bioassay Model

BACKGROUND

Collagen-based three-dimensional (3D) in vitro systems have been introduced to study the physiological states of cells. As a biomolecule, collagen is usually extracted from terrestrial animals whilst aquatic animals like squid contain large amounts of collagen.

METHODS

In order to make effective use of marine organisms, we selected Persian Gulf squid in 2015 to extract the required collagen. Then, a 3D culture system based on the extracted collagen was applied to investigate cellular mechanisms in a native microenvironment. The formed collagen gel was used to investigate the growth of MDA-MB-231 breast cancer cells as well as responses to pectic acid.

RESULTS

The results revealed that the extracted collagen contained α, ß and γ components with high water holding capacity. This collagen formed a gel-like structure, which could promote the proliferation of MDA-MB-231 breast cancer cells. The MDA-MB-231 cells' viability in presence of pectic acid, demonstrating the cells' behavior in a 3D culture system.

CONCLUSION

It seems that the collagen extracted from squid skin has type I collagen properties. It might be used as a substrate in 3D cell culture systems.

Prostate cancer cells specifically reorganize epithelial cell-fibroblast communication through proteoglycan and junction pathways

Microenvironment and stromal fibroblasts are able to inhibit tumor cell proliferation both through secreted signaling molecules and direct cell-cell interactions but molecular mechanisms of these effects remain unclear. In this study, we investigated a role of cell-cell contact-related molecules (protein ECM components, proteoglycans (PGs) and junction-related molecules) in intercellular communications between the human TERT immortalized fibroblasts (BjTERT fibroblasts) and normal (PNT2) or cancer (LNCaP, PC3, DU145) prostate epithelial cells. It was shown that BjTERT-PNT2 cell coculture resulted in significant decrease of both BjTERT and PNT2 proliferation rates and reorganization of transcriptional activity of cell-cell contact-related genes in both cell types. Immunocytochemical staining revealed redistribution of DCN and LUM in PNT2 cells and significant increase of SDC1 at the intercellular contact zones between BjTERT and PNT2 cells, suggesting active involvement of the PGs in cell-cell contacts and contact inhibition of cell proliferation. Unlike to PNT2 cells, PC3 cells did not respond to BjTERT in terms of PGs expression, moderately increased transcriptional activity of junctions-related genes (especially tight junction) and failed to establish PC3-BjTERT contacts. At the same time, PC3 cells significantly down-regulated junctions-related genes (especially focal adhesions and adherens junctions) in BjTERT fibroblasts resulting in visible preference for homotypic PC3-PC3 over heterotypic PC3-BjTERT contacts and autonomous growth of PC3 clones. Taken together, the results demonstrate that an instructing role of fibroblasts to normal prostate epithelial cells is revoked by cancer cells through deregulation of proteoglycans and junction molecules expression and overall disorganization of fibroblast-cancer cell communication.

Advances in prostate cancer research models: From transgenic mice to tumor xenografting models

The identification of the origin and molecular characteristics of prostate cancer (PCa) has crucial implications for personalized treatment. The development of effective treatments for PCa has been limited; however, the recent establishment of several transgenic mouse lines and/or xenografting models is better reflecting the disease in vivo. With appropriate models, valuable tools for elucidating the functions of specific genes have gone deep into prostate development and carcinogenesis. In the present review, we summarize a number of important PCa research models established in our laboratories (PSA-Cre-ER^T2/PTEN transgenic mouse models, AP-OX model, tissue recombination-xenografting models and PDX models), which represent advances of translational models from transgenic mouse lines to human tumor xenografting. Better understanding of the developments of these models will offer new insights into tumor progression and may help explain the functional significance of genetic variations in PCa. Additionally, this understanding could lead to new modes for curing PCa based on their particular biological phenotypes.

PD-1, PD-L1 and PD-L2 expression in mouse prostate cancer

Programmed cell death protein 1 (PD-1) and its ligands PD-L1 and PD-L2 play critical roles in maintaining an immunosuppressive tumor microenvironment. The purpose of the present study was to assess expression of PD-1, PD-L1, and PD-L2 in mouse prostate tumors. A total of 33 mouse prostate tumors derived from Pten-null mice were examined using immunohistochemical staining for PD-1, PD-L1, and PD-L2. The animals were either with interleukin-17 receptor c (Il-17rc) wild-type or knockout genotype, or fed with regular diet or high-fat diet to 30 weeks of age. We found that Il-17rc wild-type mouse prostate tumors had significantly higher levels of PD-1, PD-L1, and PD-L2 than Il-17rc knockout mouse prostate tumors. High-fat diet-induced obese mice had significantly higher levels of PD-1, PD-L1, and PD-L2 in their prostate tumors than lean mice fed with regular diet. Increased expression of PD-1, PD-L1, and PD-L2 was associated with increased number of invasive prostate tumors formed in the Il-17rc wild-type and obese mice compared to the Il-17rc knockout and lean mice, respectively. Our findings suggest that expression of PD-1, PD-L1, and PD-L2 may enhance development of mouse prostate cancer through creating an immunosuppressive tumor microenvironment.

Multiple myeloma cell lines and primary tumors proteoma: protein biosynthesis and immune system as potential therapeutic targets

Despite great advance in multiple myeloma (MM) treatment since 2000s, it is still an incurable disease and novel therapies are welcome. Therefore, the purpose of this study was to explore MM plasma cells' (MM-PC) proteome, in comparison with their normal counterparts (derived from palatine tonsils of normal donors, ND-PC), in order to find potential therapeutic targets expressed on the surface of these cells. We also aimed to evaluate the proteome of MM cell lines with different genetic alterations, to confirm findings obtained with primary tumor cells. Bone marrow (BM) samples from eight new cases of MM and palatine tonsils from seven unmatched controls were submitted to PC separation and, in addition to two MM cell lines (U266, RPMI-8226), were submitted to protein extraction for mass spectrometry analyses. A total of 81 proteins were differentially expressed between MM-PC and ND-PC - 72 upregulated and nine downregulated; U266 vs. RPMI 8226 cell lines presented 61 differentially expressed proteins - 51 upregulated and 10 downregulated. On primary tumors, bioinformatics analyses highlighted upregulation of protein biosynthesis machinery, as well as downregulation of immune response components, such as MHC class I and II, and complement receptors. We also provided comprehensive information about U266 and RPMI-8226 cell lines' proteome and could confirm some patients' findings.

Disruptive environmental chemicals and cellular mechanisms that confer resistance to cell death

Cell death is a process of dying within biological cells that are ceasing to function. This process is essential in regulating organism development, tissue homeostasis, and to eliminate cells in the body that are irreparably damaged. In general, dysfunction in normal cellular death is tightly linked to cancer progression. Specifically, the up-regulation of pro-survival factors, including oncogenic factors and antiapoptotic signaling pathways, and the down-regulation of pro-apoptotic factors, including tumor suppressive factors, confers resistance to cell death in tumor cells, which supports the emergence of a fully immortalized cellular phenotype. This review considers the potential relevance of ubiquitous environmental chemical exposures that have been shown to disrupt key pathways and mechanisms associated with this sort of dysfunction. Specifically, bisphenol A, chlorothalonil, dibutyl phthalate, dichlorvos, lindane, linuron, methoxychlor and oxyfluorfen are discussed as prototypical chemical disruptors; as their effects relate to resistance to cell death, as constituents within environmental mixtures and as potential contributors to environmental carcinogenesis.

Mechanisms of environmental chemicals that enable the cancer hallmark of evasion of growth suppression

As part of the Halifax Project, this review brings attention to the potential effects of environmental chemicals on important molecular and cellular regulators of the cancer hallmark of evading growth suppression. Specifically, we review the mechanisms by which cancer cells escape the growth-inhibitory signals of p53, retinoblastoma protein, transforming growth factor-beta, gap junctions and contact inhibition. We discuss the effects of selected environmental chemicals on these mechanisms of growth inhibition and cross-reference the effects of these chemicals in other classical cancer hallmarks.

Prognostic Impacts of Metastatic Site and Pain on Progression to Castrate Resistance and Mortality in Patients with Metastatic Prostate Cancer

PURPOSE

To investigate predictors of progression to castration-resistant prostate cancer (CRPC) and cancer-specific mortality (CSM) in patients with metastatic prostate cancer (mPCa).

MATERIALS AND METHODS

A retrospective analysis was performed on 440 consecutive treatment-naïve patients initially diagnosed with mPCa between August 2000 and June 2012. Patient age, body mass index (BMI), Gleason score, prostate-specific antigen (PSA), PSA nadir, American Joint Committee on Cancer stage, Visual Analogue Scale pain score, Eastern Cooperative Oncology Group performance score (ECOG PS), PSA response to hormone therapy, and metastatic sites were assessed. Cox-proportional hazards regression analyses were used to evaluate survivals and predictive variables of men with bone metastasis stratified according to the presence of pain, compared to men with visceral metastasis.

RESULTS

Metastases were most often found in bone (75.4%), followed by lung (16.3%) and liver (8.3%) tissues. Bone metastasis, pain, and high BMI were associated with increased risks of progression to CRPC, and bone metastasis, pain, PSA nadir, and ECOG PS≥1 were significant predictors of CSM. During the median follow-up of 32.0 (interquartile range 14.7-55.9) months, patients with bone metastasis with pain and patients with both bone and visceral metastases showed the worst median progression to CRPC-free and cancer-specific survivals, followed by men with bone metastasis without pain. Patients with visceral metastasis had the best median survivals.

CONCLUSION

Metastatic spread and pain patterns confer different prognosis in patients with mPCa. Bone may serve as a crucial microenvironment in the development of CRPC and disease progression.