Inflammation-associated regulation of the macrophage inhibitory cytokine (MIC-1) gene in prostate cancer

The Roles of Tumor-Associated Macrophages in Prostate Cancer

The morbidity of prostate cancer (PCa) is rising year by year, and it has become the primary cause of tumor-related mortality in males. It is widely accepted that macrophages account for 50% of the tumor mass in solid tumors and have emerged as a crucial participator in multiple stages of PCa, with the huge potential for further treatment. Oftentimes, tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) behave like M2-like phenotypes that modulate malignant hallmarks of tumor lesions, ranging from tumorigenesis to metastasis. Several clinical studies indicated that mean TAM density was higher in human PCa cores versus benign prostatic hyperplasia (BPH), and increased biopsy TAM density potentially predicts worse clinicopathological characteristics as well. Therefore, TAM represents a promising target for therapeutic intervention either alone or in combination with other strategies to halt the “vicious cycle,” thus improving oncological outcomes. Herein, we mainly focus on the fundamental aspects of TAMs in prostate adenocarcinoma, while reviewing the mechanisms responsible for macrophage recruitment and polarization, which has clinical translational implications for the exploitation of potentially effective therapies against TAMs.

microRNA-211-mediated targeting of the INHBA-TGF-β axis suppresses prostate tumor formation and growth

Prostate cancer (PCa) stem cells increase the sustainability of tumor growth, resulting in high relapse rates in patients with PCa. This goal of the present study was to elucidate the function of microRNA (miR)-211 in PCa stem cell activities. Based on the initial findings from the GSE26910 dataset, inhibin-β A (INHBA) was used for subsequent experiments, and miR-211 was then predicted as a candidate regulatory miR. Subsequently, INHBA and miR-211 were observed to be highly and poorly expressed in PCa tissues, respectively, and miR-211 negatively target INHBA. CD44⁺CD133⁺ cells were isolated, and both miR-211 and INHBA expression was altered in these cells to assess functional role of miR-211 and INHBA in PCa stem cells. Overexpression of miR-211 decreased expression of TGF-β1, TGF-β2, smad2, smad3, phosphorylated smad2 and smad3, and stem cell markers. miR-211 upregulation or INHBA knockdown resulted in reductions in the proliferation, invasion, colony-forming ability, sphere-forming ability, and stemness of PCa stem cells but enhanced their apoptosis in vitro. Furthermore, miR-211 upregulation or INHBA silencing decreased tumor growth and cell apoptosis in vivo. Taken together, these results indicate that upregulation of miR-211 has tumor-suppressive properties by inhibiting TGF-β pathway activation via INHBA in PCa stem cells.

Inflammation in Prostatic Hyperplasia and Carcinoma-Basic Scientific Approach

Chronic inflammation is associated with both benign conditions and cancer. Likewise, inflammatory cells are quite common in benign prostatic hyperplasia (BPH) and prostatic tissue harboring cancer. Triggers that activate inflammatory pathways in the prostate remain a subject of argument and are likely to be multifactorial, some of these being bacterial antigens, different chemical irritations, and metabolic disorders. Acute and chronic inflammation in prostate leads to accumulation of immunocompetent cells, mainly T lymphocytes and macrophages, but also neutrophils, eosinophils, and mast cells, depending on the type of offending agent. Inflammatory processes activate hyperproliferative programs resulting in nodules seen in BPH, but are also important in creating suitable microenvironment for cancer growth and progression. Inflammatory cells have mostly been shown to have a protumoral effect such as tumor-associated macrophages, but some cell types such as mast cells have antitumoral effects. This review outlines the recent findings and theories supporting the role of inflammatory responses as drivers of both benign and malignant epithelial processes in the prostate gland.

Cancer and inflammation

The relationship between inflammation and cancer has been recognized since the 17^th century,¹ and we now know much about the cells, cytokines and physiological processes that are central to both inflammation and cancer.^2-9 Chronic inflammation can induce certain cancers,^10-17 and solid tumors, in turn, can initiate and perpetuate local inflammatory processes that foster tumor growth and dissemination.⁵ ,^18-20 Consequently, inflammatory pathways have been targeted in attempts to control cancer.^21-23 Inflammation is a central aspect of the innate immune system's response to tissue damage or infection, and also facilitates the recruitment of circulating cells and antibodies of the adaptive immune response to the tissue. Components of the innate immune response carry out a robust, but sometimes overly-conservative response, sacrificing specificity for the sake of preservation. Thus, when innate immunity goes awry, it can have profound implications. How the innate and adaptive immune systems cooperate to neutralize pathogens and repair damaged tissues is still an area of intense investigation. Further, how these systems can respond to cancer, which arises from normal 'self' cells that undergo an oncogenic transformation, has profound implications for cancer therapy. Recently, immunotherapies that activate adaptive immunity have shown unprecedented promise in the clinic, producing durable responses and dramatic increases in survival rate in patients with advanced stage melanoma.^24-26 Consequently, the relationship between cancer and inflammation has now returned to the forefront of clinical oncology. WIREs Syst Biol Med 2017, 9:e1370. doi: 10.1002/wsbm.1370 For further resources related to this article, please visit the WIREs website.

Inflammation and prostate cancer: friends or foe?

INTRODUCTION

Prostate cancer is the most common non-cutaneous malignancy diagnosed in men. Moving from histological observations since a long time, it has been recognized that innate and adaptive immunity actively participates in the pathogenesis, surveillance, and progression of prostate cancer.

MATERIALS AND METHODS

A PubMed and Web of Science databases search was performed for studies providing evidence on the roles of the innate and adaptive immunity during the development and progression of prostate cancer.

CONCLUSIONS

There are growing evidences that chronic inflammation is involved in the regulation of cellular events in prostate carcinogenesis, including disruption of the immune response and regulation of the tumor microenvironment. This review discusses the role played by the innate and adaptive immune system in the local progression of prostate cancer, and the prognostic information that we can currently understand and exploit.

Linking inflammation and neuroendocrine differentiation: the role of macrophage migration inhibitory factor-mediated signaling in prostate cancer

A new paper by Tawadros et al. in Endocrine-Related Cancer demonstrates a link between macrophage migration inhibitory factor and neuroendocrine differentiation in prostate cancer. This paper may have implications in explaining the effect of prostatitis and chronic inflammation on the development of aggressive prostate cancer.

HMGB1: A Promising Therapeutic Target for Prostate Cancer

High mobility group box 1 (HMGB1) was originally discovered as a chromatin-binding protein several decades ago. It is now increasingly evident that HMGB1 plays a major role in several disease conditions such as atherosclerosis, diabetes, arthritis, sepsis, and cancer. It is intriguing how deregulation of HMGB1 can result in a myriad of disease conditions. Interestingly, HMGB1 is involved in cell proliferation, angiogenesis, and metastasis during cancer progression. Furthermore, HMGB1 has been demonstrated to exert intracellular and extracellular functions, activating key oncogenic signaling pathways. This paper focuses on the role of HMGB1 in prostate cancer development and highlights the potential of HMGB1 to serve as a key target for prostate cancer treatment.

The Prostate Cancer Patient Had Higher C-Reactive Protein Than BPH Patient

Purpose

C-reactive protein (CRP) is a general marker for inflammation and it has been associated with prostate cancer. We hypothesized that a correlation may exist between CRP and prostate cancer in patients undergoing transrectal biopsy of the prostate because of rising prostate-specific antigen (PSA) levels.

Materials and Methods

From January 2009 to March 2012, we retrospectively reviewed 710 patients who visited our urology department and were diagnosed as having a PSA value over 4.0 ng/mL. Patients with acute infections, rheumatoid arthritis, gout, asthma, chronic lung disease, myocardial infarction, or apoplexy and those who had taken nonsteroidal anti-inflammatory drugs were exempted from the research because these variables could have impacted CRP. After we applied the exclusion criteria, we selected 63 patients with prostate cancer and 140 patients with benign prostatic hyperplasia (BPH).

Results

A total of 203 patients were observed: 140 patients had BPH, and 63 patients had prostate cancer. Prostate cancer patients were divided into two groups by tumor-node-metastasis classification. The patients below T2 were group A, and those above T3 were group B. The natural logarithm of C-reactive protein (lnCRP) differed between the BPH group and the prostate cancer group. The lnCRP also differed between the BPH group and prostate cancer groups A and B (p<0.05).

Conclusions

The serum CRP level of the prostate cancer group was higher than that of the BPH group. Inflammation may be correlated with prostate cancer according to the serum CRP level.

Development of animal models underlining mechanistic connections between prostate inflammation and cancer

The characterization of animal models has indicated that the genetic, dietary and environmental factors and hormonal imbalance may influence the risk to develop prostate inflammatory lesions and prostate cancer (PC) confirming human epidemiologic data. It is now established that the prostate inflammatory response typically results in major changes in the local microenvironment of epithelial cells of the prostate gland, including an intense stromal remodeling, activation of fibroblasts, infiltration of immune cells such as mast cells, macrophages and B and T lymphocytes and collagen deposition. The immune cells recruited at prostate inflammatory lesions and myofibroblasts may contribute to the release of numerous pro-inflammatory cytokines and chemokines that in turn can promote the oxidative stress, genomic instability and proliferation of epithelial cells. The accumulation of additional genetic and/or epigenetic alterations in prostatic stem/progenitor cells may subsequently culminate to their malignant transformation and PC initiation and progression and more particularly with advancing age. The potential mechanistic relationships between the molecular events associated with the persistent inflammatory response and prostate carcinogenesis have important implications for optimizing the current therapies against different prostatic disorders and PCs.