Elevation of Stromal-Derived Mediators of Inflammation Promote Prostate Cancer Progression in African-American Men

Prostate cancer metastasis and health disparities: a systematic review

BACKGROUND

Prostate cancer (PCa), one of the most prevalent malignancies affecting men, significantly contributes to increased mortality rates worldwide. While the causative death is due to advanced metastatic disease, this occurrence disproportionately impacts men of African descent compared to men of European descent. In this review, we describe potential mechanisms underlying PCa metastases disparities and current treatments for metastatic disease among these populations, differences in treatment outcomes, and survival rates, in hopes of highlighting a need to address disparities in PCa metastases.

METHODS

We reviewed existing literature using databases such as PubMed, Google Scholar, and Science Direct using the following keywords: "prostate cancer metastases", "metastatic prostate cancer disparity", "metastatic prostate cancer diagnosis and treatment", "prostate cancer genetic differences and mechanisms", "genetic differences and prostate tumor microenvironment", and "men of African descent and access to clinical treatments". The inclusion criteria for literature usage were original research articles and review articles.

RESULTS

Studies indicate unique genetic signatures and molecular mechanisms such as Epithelial-Mesenchymal Transition (EMT), inflammation, and growth hormone signaling involved in metastatic PCa disparities. Clinical studies also demonstrate differences in treatment outcomes that are race-specific, for example, patients of African descent have a better response to enzalutamide and immunotherapy yet have less access to these drugs as compared to patients of European descent.

CONCLUSIONS

Growing evidence suggests a connection between a patient's genetic profile, the prostate tumor microenvironment, and social determinants of health that contribute to the aggressiveness of metastatic disease and treatment outcomes. With several potential pathways highlighted, the limitations in current diagnostic and therapeutic applications that target disparity in PCa metastases warrant rigorous research attention.

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.

The complex interplay of modifiable risk factors affecting prostate cancer disparities in African American men

Prostate cancer is the second most commonly diagnosed non-skin malignancy and the second leading cause of cancer death among men in the USA. However, the mortality rate of African American men aged 40-60 years is almost 2.5-fold greater than that of European American men. Despite screening and diagnostic and therapeutic advances, disparities in prostate cancer incidence and outcomes remain prevalent. The reasons that lead to this disparity in outcomes are complex and multifactorial. Established non-modifiable risk factors such as age and genetic predisposition contribute to this disparity; however, evidence suggests that modifiable risk factors (including social determinants of health, diet, steroid hormones, environment and lack of diversity in enrolment in clinical trials) are prominent contributing factors to the racial disparities observed. Disparities involved in the diagnosis, treatment and survival of African American men with prostate cancer have also been correlated with low socioeconomic status, education and lack of access to health care. The effects and complex interactions of prostate cancer modifiable risk factors are important considerations for mitigating the incidence and outcomes of this disease in African American men.

Microfluidic-based human prostate-cancer-on-chip

Lack of adequate models significantly hinders advances in prostate cancer treatment, where resistance to androgen-deprivation therapies and bone metastasis remain as major challenges. Current in vitro models fail to faithfully mimic the complex prostate physiology. In vivo animal models can shed light on the oncogenes involved in prostate cancer development and progression; however, the animal prostate gland is fundamentally different from that of human, and the underlying genetic mechanisms are different. To address this problem, we developed the first in vitro microfluidic human Prostate-Cancer-on-Chip (PCoC) model, where human prostate cancer and stromal fibroblast cells were co-cultivated in two channels separated by a porous membrane under culture medium flow. The established microenvironment enables soluble signaling factors secreted by each culture to locally diffuse through the membrane pores affecting the neighboring culture. We particularly explored the conversion of the stromal fibroblasts into cancer-associated fibroblasts (CAFs) due to the interaction between the 2 cell types. Immunofluorescence microscopy revealed that tumor cells induced CAF biomarkers, αSMA and COL1A1, in stromal fibroblasts. The stromal CAF conversion level was observed to increase along the flow direction in response to diffusion agents, consistent with simulations of solute concentration gradients. The tumor cells also downregulated androgen receptor (AR) expression in stromal fibroblasts, while an adequate level of stromal AR expression is maintained in normal prostate homeostasis. We further investigated tumor invasion into the stroma, an early step in the metastatic cascade, in devices featuring a serpentine channel with orthogonal channel segments overlaying a straight channel and separated by an 8 µm-pore membrane. Both tumor cells and stromal CAFs were observed to cross over into their neighboring channel, and the stroma's role seemed to be proactive in promoting cell invasion. As control, normal epithelial cells neither induced CAF conversion nor promoted cell invasion. In summary, the developed PCoC model allows spatiotemporal analysis of the tumor-stroma dynamic interactions, due to bi-directional signaling and physical contact, recapitulating tissue-level multicellular responses associated with prostate cancer in vivo. Hence, it can serve as an in vitro model to dissect mechanisms in human prostate cancer development and seek advanced therapeutic strategies.

Genetic and biological drivers of prostate cancer disparities in Black men

Black men with prostate cancer have historically had worse outcomes than white men with prostate cancer. The causes of this disparity in outcomes are multi-factorial, but a potential basis is that prostate cancers in Black men are biologically distinct from prostate cancers in white men. Evidence suggests that genetic and ancestral factors, molecular pathways involving androgen and non-androgen receptor signalling, inflammation, epigenetics, the tumour microenvironment and tumour metabolism are contributing factors to the racial disparities observed. Key genetic and molecular pathways linked to prostate cancer risk and aggressiveness have potential clinical relevance. Describing biological drivers of prostate cancer disparities could inform efforts to improve outcomes for Black men with prostate cancer.

Immunologic Assessment of Tumors from a Race-matched Military Cohort Identifies Mast Cell Depletion as a Marker of Prostate Cancer Progression

Elucidating the cellular immune components underlying aggressive prostate cancer, especially among African American (AA) men who are disproportionately affected by this disease compared with Caucasian American (CA) men, will support more inclusive precision medicine treatment strategies. We aimed to evaluate which immune-related genes and cell types are differentially expressed in AA tumors and how immunobiology impacts prostate cancer progression. We purified nucleic acid from tumor biopsies, obtained following radical prostatectomy, from 51 patients (AA = 26, CA = 25). Gene expression was measured using the NanoString platform from which we estimated immune cell abundances and assessed differences between groups based on clinicopathologic data. Product-limit estimates determined associations with biochemical recurrence (BCR)-free and metastasis-free survival. DVL2 and KLRC2 were significantly upregulated in CA tumors and were also associated with worse disease progression. No significant differences in immune cell abundances by race were observed. Highly significant reductions in abundances of mast cells versus tumor-infiltrating lymphocytes (TIL) were found in men with high-grade pathologies and in men who later developed metastases. Low ratios of mast cells versus TILs were associated with worse BCR-free survival and metastasis-free survival. Although estimated immune cell abundances were not different by race, we identified genes involved in metabolism and natural killer cell functions that were differentially expressed between AA and CA tumors. Among the entire cohort, depletion of mast cells within prostatectomy tumors was characteristic of advanced disease and susceptibility to disease progression.

Significance

Our findings demonstrate that there are immune-related genes and pathways that differ by race. Impaired intratumoral cellular immune composition, especially for TIL-normalized mast cells, may be vital in predicting and contributing to prostate cancer disease progression.

The Molecular Basis and Clinical Consequences of Chronic Inflammation in Prostatic Diseases: Prostatitis, Benign Prostatic Hyperplasia, and Prostate Cancer

Chronic inflammation is now recognized as one of the major risk factors and molecular hallmarks of chronic prostatitis, benign prostatic hyperplasia (BPH), and prostate tumorigenesis. However, the molecular mechanisms by which chronic inflammation signaling contributes to the pathogenesis of these prostate diseases are poorly understood. Previous efforts to therapeutically target the upstream (e.g., TLRs and IL1-Rs) and downstream (e.g., NF-κB subunits and cytokines) inflammatory signaling molecules in people with these conditions have been clinically ambiguous and unsatisfactory, hence fostering the recent paradigm shift towards unraveling and understanding the functional roles and clinical significance of the novel and relatively underexplored inflammatory molecules and pathways that could become potential therapeutic targets in managing prostatic diseases. In this review article, we exclusively discuss the causal and molecular drivers of prostatitis, BPH, and prostate tumorigenesis, as well as the potential impacts of microbiome dysbiosis and chronic inflammation in promoting prostate pathologies. We specifically focus on the importance of some of the underexplored druggable inflammatory molecules, by discussing how their aberrant signaling could promote prostate cancer (PCa) stemness, neuroendocrine differentiation, castration resistance, metabolic reprogramming, and immunosuppression. The potential contribution of the IL1R-TLR-IRAK-NF-κBs signaling molecules and NLR/inflammasomes in prostate pathologies, as well as the prospective benefits of selectively targeting the midstream molecules in the various inflammatory cascades, are also discussed. Though this review concentrates more on PCa, we envision that the information could be applied to other prostate diseases. In conclusion, we have underlined the molecular mechanisms and signaling pathways that may need to be targeted and/or further investigated to better understand the association between chronic inflammation and prostate diseases.

Fibroblasts as Turned Agents in Cancer Progression

Differentiated epithelial cells reside in the homeostatic microenvironment of the native organ stroma. The stroma supports their normal function, their G0 differentiated state, and their expansion/contraction through the various stages of the life cycle and physiologic functions of the host. When malignant transformation begins, the microenvironment tries to suppress and eliminate the transformed cells, while cancer cells, in turn, try to resist these suppressive efforts. The tumor microenvironment encompasses a large variety of cell types recruited by the tumor to perform different functions, among which fibroblasts are the most abundant. The dynamics of the mutual relationship change as the sides undertake an epic battle for control of the other. In the process, the cancer “wounds” the microenvironment through a variety of mechanisms and attracts distant mesenchymal stem cells to change their function from one attempting to suppress the cancer, to one that supports its growth, survival, and metastasis. Analogous reciprocal interactions occur as well between disseminated cancer cells and the metastatic microenvironment, where the microenvironment attempts to eliminate cancer cells or suppress their proliferation. However, the altered microenvironmental cells acquire novel characteristics that support malignant progression. Investigations have attempted to use these traits as targets of novel therapeutic approaches.

Immune mechanisms behind prostate cancer in men of African ancestry: A review

BACKGROUND

Men of African ancestry (AA) with prostate cancer suffer from worse outcomes. However, a recent analysis of patients treated with the dendritic cell vaccine sipuleucel-T for prostate cancer suggested that AA patients could have improved outcomes relative to whites.

METHODS

We conducted a focused literature review of Medline-indexed articles and clinical trials listed on clinicaltrials.gov.

RESULTS

We identify several studies pointing to enrichment of inflammatory cellular infiltrates and cytokine signaling among AA patients with prostate cancer. We outline potential genomic and transcriptomic alterations that may contribute to immunogenicity. Last, we investigate differences in host immunity and vaccine responsiveness that may be enhanced in AA patients.

CONCLUSIONS

AA patients with prostate cancer may be enriched for an immunogenic phenotype. Dedicated studies are needed to better understand the immune mechanisms that contribute to existing cancer disparities and test immune-based therapies in this population.

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.

Racial disparities in prostate cancer: A complex interplay between socioeconomic inequities and genomics

The largest US cancer health disparity exists in prostate cancer, with Black men having more than a two-fold increased risk of dying from prostate cancer compared to all other races. This disparity is a result of a complex network of factors including socioeconomic status (SES), environmental exposures, and genetics/biology. Inequity in the US healthcare system has emerged as a major driver of disparity in prostate cancer outcomes and has raised concerns that the actual incidence rates may be higher than current estimates. However, emerging studies argue that equalizing healthcare access will not fully eliminate racial health disparities and highlight the important role of biology. Significant differences have been observed in prostate cancer biology between various ancestral groups that may contribute to prostate cancer health disparities. These differences include enhanced androgen receptor signaling, increased genomic instability, metabolic dysregulation, and enhanced inflammatory and cytokine signaling. Immediate actions are needed to increase the establishment of adequate infrastructure and multi-center, interdisciplinary research to bridge the gap between social and biological determinants of prostate cancer health disparities.

Immune response and inflammation in cancer health disparities

Cancer death rates vary among population groups. Underserved populations continue to experience an excessive burden of lethal cancers that is largely explained by health-care disparities. However, the prominent role of advanced-stage disease as a driver of cancer survival disparities may indicate that some cancers are more aggressive in certain population groups than others. The tumor mutational burden can show large differences among patients with similar-stage disease but differences in race/ethnicity or residence. These dissimilarities may result from environmental or chronic inflammatory exposures, altering tumor biology and the immune response. We discuss the evidence that inflammation and immune response dissimilarities among population groups contribute to cancer disparities and how they can be targeted to reduce these disparities.

A Review of Prostate Organogenesis and a Role for iPSC-Derived Prostate Organoids to Study Prostate Development and Disease

The prostate is vulnerable to two major age-associated diseases, cancer and benign enlargement, which account for significant morbidity and mortality for men across the globe. Prostate cancer is the most common cancer reported in men, with over 1.2 million new cases diagnosed and 350,000 deaths recorded annually worldwide. Benign prostatic hyperplasia (BPH), characterised by the continuous enlargement of the adult prostate, symptomatically afflicts around 50% of men worldwide. A better understanding of the biological processes underpinning these diseases is needed to generate new treatment approaches. Developmental studies of the prostate have shed some light on the processes essential for prostate organogenesis, with many of these up- or downregulated genes expressions also observed in prostate cancer and/or BPH progression. These insights into human disease have been inferred through comparative biological studies relying primarily on rodent models. However, directly observing mechanisms of human prostate development has been more challenging due to limitations in accessing human foetal material. Induced pluripotent stem cells (iPSCs) could provide a suitable alternative as they can mimic embryonic cells, and iPSC-derived prostate organoids present a significant opportunity to study early human prostate developmental processes. In this review, we discuss the current understanding of prostate development and its relevance to prostate-associated diseases. Additionally, we detail the potential of iPSC-derived prostate organoids for studying human prostate development and disease.

Analysis of Circulating Immune Biomarkers by Race in Men with Metastatic Castration-Resistant Prostate Cancer Treated with Sipuleucel-T

Among racial subgroups, Black men have the highest prostate cancer–specific death rate, yet they also exhibit prolonged overall survival compared with White men when treated with standard therapies, including sipuleucel-T. Differential immune responses may play a role in these observations. We compared circulating immune markers from 54 men (18 Black and 36 White) with metastatic castrate-resistant prostate cancer who received sipuleucel-T and were enrolled on an immune monitoring registry. Markers included longitudinal serum cytokine concentrations, humoral responses, and cellular immunity from baseline until 52 weeks after sipuleucel-T administration. Black men had statistically significantly higher median concentrations of T_H2-type (interleukin [IL]-4, IL-10, and IL-13) and inflammatory cytokines (IL-2, IL-12, and IL-6) compared with prostate-specific antigen-matched White men both at baseline and 52 weeks after sipuleucel-T (2-sided P < .05). No differences by race were seen in either the antigen-specific T-cell response or the humoral responses to the immunizing antigen PA2024 and select secondary antigens.

Immune Inflammation Pathways as Therapeutic Targets to Reduce Lethal Prostate Cancer in African American Men

Despite substantial improvements in cancer survival, not all population groups have benefitted equally from this progress. For prostate cancer, men of African descent in the United States and England continue to have about double the rate of fatal disease compared to other men. Studies suggest that when there is equal access to care, survival disparities are greatly diminished. However, notable differences exist in prostate tumor biology across population groups. Ancestral factors and disparate exposures can lead to altered tumor biology, resulting in a distinct disease etiology by population group. While equal care remains the key target to improve survival, additional efforts should be made to gain comprehensive knowledge of the tumor biology in prostate cancer patients of African descent. Such an approach may identify novel intervention strategies in the era of precision medicine. A growing body of evidence shows that inflammation and the immune response may play a distinct role in prostate cancer disparities. Low-grade chronic inflammation and an inflammatory tumor microenvironment are more prevalent in African American patients and have been associated with adverse outcomes. Thus, differences in activation of immune-inflammatory pathways between African American and European American men with prostate cancer may exist. These differences may influence the response to immune therapy which is consistent with recent observations. This review will discuss mechanisms by which inflammation may contribute to the disparate outcomes experienced by African American men with prostate cancer and how these immunogenic and inflammatory vulnerabilities could be exploited to improve their survival.

Race as a Contributor to Stromal Modulation of Tumor Progression

Stromal cells play crucial roles in tumor development and are increasingly attractive targets for therapy. There are considerable racial disparities in the incidence and progression of many tumors, reflecting both environmental exposure and genetic differences existing between races. Tumorigenesis and tumor progression are linked to both the propensity to suffer an initiating event and the host response to such an event once it occurs, contributing to incidence and outcomes. In this review, we focused on racial disparities in the tumor microenvironment (TME) of different cancers as potential modulators of growth, metastasis, and response to treatment. Several studies suggest that the TME in AA has a distinct tumor biology and may facilitate both early onset and aggressive tumor growth while inhibiting anti-tumorigenic properties. The TME of AA patients often exhibits an immunosuppressive microenvironment with a substantial enrichment of immune inflammatory pathways and genes. As a result, AA patients can potentially benefit more from treatment strategies that modulate the immune system. Focusing on TME components for diagnostic and therapeutic purposes to address racial disparities is a promising area of investigation. Future basic and clinical research studies on personalized cancer diagnosis and treatment should acknowledge the significance of TME in racial disparities.

Adherence to the Mediterranean diet and grade group progression in localized prostate cancer: An active surveillance cohort

BACKGROUND

The Mediterranean diet (MD) may be beneficial for men with localized prostate cancer (PCa) on active surveillance (AS) because of its anti-inflammatory, antilipidemic, and chemopreventive properties. This study prospectively investigated adherence to the MD with Gleason score progression and explored associations by diabetes status, statin use, and other factors.

METHODS

Men with newly diagnosed PCa on an AS protocol (n = 410) completed a baseline food frequency questionnaire, and the MD score was calculated across 9 energy-adjusted food groups. Cox proportional hazards models were fit to evaluate multivariable-adjusted associations of the MD score with progression-free survival; progression was defined as an increase in the Gleason grade group (GG) score over a biennial monitoring regimen.

RESULTS

In this cohort, 15% of the men were diabetic, 44% of the men used statins, and 76 men progressed (median follow-up, 36 months). After adjustments for clinical factors, higher adherence to the MD was associated with a lower risk of GG progression among all men (hazard ratio [HR] per 1-unit increase in MD score, 0.88; 95% confidence interval [CI], 0.77-1.01), non-White men (HR per 1-unit increase in MD score, 0.64; 95% CI, 0.45-0.92; P for interaction = .07), and men without diabetes (HR per 1-unit increase in MD score, 0.82; 95% CI, 0.71-0.96; P for interaction = .03). When joint effects of the MD score and statin use were examined, a similar risk reduction was observed among men with high MD scores who did not use statins in comparison with men with low/moderate MD scores with no statin use.

CONCLUSIONS

The MD is associated with a lower risk of GG progression in men on AS, and this is consistent with prior reports about the MD and reduced cancer morbidity and mortality.

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.

Comparative Genomics Reveals Distinct Immune-oncologic Pathways in African American Men with Prostate Cancer

PURPOSE

The role of immune-oncologic mechanisms of racial disparities in prostate cancer remains understudied. Limited research exists to evaluate the molecular underpinnings of immune differences in African American men (AAM) and European American men (EAM) prostate tumor microenvironment (TME).

EXPERIMENTAL DESIGN

A total of 1,173 radiation-naïve radical prostatectomy samples with whole transcriptome data from the Decipher GRID registry were used. Transcriptomic expressions of 1,260 immune-specific genes were selected to assess immune-oncologic differences between AAM and EAM prostate tumors. Race-specific differential expression of genes was assessed using a rank test, and intergene correlational matrix and gene set enrichment was used for pathway analysis.

RESULTS

AAM prostate tumors have significant enrichment of major immune-oncologic pathways, including proinflammatory cytokines, IFNα, IFNγ, TNFα signaling, ILs, and epithelial-mesenchymal transition. AAM TME has higher total immune content score (ICS^HIGH) compared with 0 (37.8% vs. 21.9%, P = 0.003). AAM tumors also have lower DNA damage repair and are genomically radiosensitive as compared with EAM. IFITM3 (IFN-inducible transmembrane protein 3) was one of the major proinflammatory genes overexpressed in AAM that predicted increased risk of biochemical recurrence selectively for AAM in both discovery [HR_AAM = 2.30; 95% confidence interval (CI), 1.21-4.34; P = 0.01] and validation (HR_AAM = 2.42; 95% CI, 1.52-3.86; P = 0.0001) but not in EAM.

CONCLUSIONS

Prostate tumors of AAM manifest a unique immune repertoire and have significant enrichment of proinflammatory immune pathways that are associated with poorer outcomes. Observed immune-oncologic differences can aid in a genomically adaptive approach to treating prostate cancer in AAM.

Tumour innervation and neurosignalling in prostate cancer

Prostate cancer progression has been shown to be dependent on the development of autonomic nerves into the tumour microenvironment. Sympathetic nerves activate adrenergic neurosignalling that is necessary in early stages of tumour progression and for initiating an angiogenic switch, whereas parasympathetic nerves activate cholinergic neurosignalling resulting in tumour dissemination and metastasis. The innervation of prostate cancer seems to be initiated by neurotrophic growth factors, such as the precursor to nerve growth factor secreted by tumour cells, and the contribution of brain-derived neural progenitor cells has also been reported. Current experimental, epidemiological and clinical evidence shows the stimulatory effect of tumour innervation and neurosignalling in prostate cancer. Using nerves and neurosignalling could have value in the management of prostate cancer by predicting aggressive disease, treating localized disease through denervation and relieving cancer-associated pain in bone metastases.

Genomic alterations of Tenascin C in highly aggressive prostate cancer: a meta-analysis

Tenascin C (TNC), an extra-cellular matrix (ECM) family gene, is expressed in several cancer tissues of breast, lung, colon, and gastrointestinal tract leading to proliferation, migration, invasion, angiogenesis and metastasis, but its role in tumorigenesis of prostate cancer is poorly understood. We took a meta-analysis approach to characterize the alterations of TNC gene in prostate cancer using publicly available databases (cBioportal Version 2.2.0, http://www.cBioportal.org/index.do). The analysis identified TNC alterations (gene amplification) significantly in the neuroendocrine prostate cancer dataset (Trento/Broad/Cornell, N = 114), which was further validated in other prostate cancer datasets, including The Cancer Genome Atlas (TCGA) prostate cancer (2015). In the TCGA prostate cancer dataset (N = 498), high TNC (alteration frequency, 36%) revealed a strong association with high diagnostic Gleason score. Genomic alterations of TNC was also significantly associated (P < 0.05) with expression level of genes from NOTCH, SOX and WNT family, implicating a link between TNC and poorly differentiated aggressive phenotype in NEPC. TCGA prostate adenocarcinoma cases with TNC alteration also demonstrated prominent decrease in disease-free survival (P = 0.0637). These findings indicate a possible association of TNC to the aggressive subtype of prostate cancer and warrant further functional studies to evident the involvement of TNC in prostate cancer progression.

Race-associated expression of MHC class I polypeptide-related sequence A (MICA) in prostate cancer

Despite the lack of a complete understanding of the disparities involved, prostate cancer (PCa) has both higher incidence and death rates in African American Men (AAM) relative to those of Caucasian American Men (CAM). MHC class I polypeptide related sequence A (MICA) is an innate immunity protein involved in tumor immunoevasion. Due to a lack of reports of race-specific expression of MICA in PCa, we evaluated MICA expression in patients' tumors and in cell lines from a racially diverse origin. Immunohistochemistry was done on a tissue microarray (TMA) with antibodies against MICA. Tumor MICA mRNA was assessed by data mining using Oncomine and PROGeneV2. Surface MICA and release rate of soluble (s) MICA was evaluated in PCa cell lines originally derived from African American (MDA-PCa-2b) or Caucasian (LNCaP and DU-145) PCa patients. Prostate tumor tissue had a 1.7-fold higher MICA expression relative to normal tissue (p < .0001). MICA immunoreactivity in PCa tissue from AAM was 24% lower (p = .002) compared to CAM. Survival analysis revealed a marginal association of low MICA with poor overall survival (OS) (p = .058). By data mining analysis, a 2.9-fold higher level of MICA mRNA was evidenced in tumor compared to normal tissue (p < .0001). Tumors from AAM had 24% lower levels of MICA mRNA compared to tumors from CAM (p = .038), and poor prognosis was found for patients with lower MICA mRNA (p = .028). By flow cytometry analysis, cell fraction positive for surface MICA was of 3% in MDA-PCa-2b cells, 54% in DU-145 cells, and 67% in LNCaP cells (p < .0001). sMICA was detected in DU-145 and LNCaP cells, but was not detected in MDA-PCa-2b cells. Both LNCaP and DU-145 cells were sensitive to cytolysis mediated by Natural killer (NK) cells. MDA-PCa-2b cells, however were between 1.3-fold at 10:1 Effector:Target (E:T) ratio (p < .0001) and 2-fold at 50:1 E:T ratio (p < .0001) more resistant to NK-mediated cytolysis relative to cells from Caucasian origin. These results suggest that MICA expression may be related to the aggressive nature of PCa. Our findings also demonstrate for the first time that there are variations in MICA expression in the context of racial differences. This study establishes a rationale for further investigation of MICA as a potential race-specific prognostic marker in PCa.

DGAT1 Inhibitor Suppresses Prostate Tumor Growth and Migration by Regulating Intracellular Lipids and Non-Centrosomal MTOC Protein GM130

Acyl-CoA:diacylglycerol acyltransferase I (DGAT1) is a key enzyme in lipogenesis which is increased in metabolically active cells to meet nutrient requirements. DGAT1 has been recognized as an anti-obesity target; however, its role in the tumor microenvironment remains unclear. We postulated that, in prostate cancer (PCa) cells, augmented lipogenesis and growth are due to increased DGAT1 expression leading to microtubule-organizing center (MTOC) amplification. Thus, therapeutic targeting of DGAT1 potentially has tumor suppressive activity. We tested whether blocking DGAT1 in PCa cells altered MTOC and lipid signaling. Western blot and immunofluorescence were performed for MTOC and triglyceride mediators. Treatment with a DGAT1 inhibitor was evaluated. We found a stepwise increase in DGAT1 protein levels when comparing normal prostate epithelial cells to PCa cells, LNCaP and PC-3. Lipid droplets, MTOCs, and microtubule-regulating proteins were reduced in tumor cells treated with a DGAT1 inhibitor. Depletion of the non-centrosomal MTOC protein GM130 reduced PCa cell proliferation and migration. Inhibition of DGAT1 reduced tumor growth both in vitro and in vivo, and a negative feedback loop was discovered between DGAT1, PEDF, and GM130. These data identify DGAT1 as a promising new target for suppressing PCa growth by regulating GM130, MTOC number and disrupting microtubule integrity.