Chemokines and chemokine receptors as promoters of prostate cancer growth and progression

The endogenous cell-fate factor dachshund restrains prostate epithelial cell migration via repression of cytokine secretion via a cxcl signaling module

Prostate cancer is the second leading form of cancer-related death in men. In a subset of prostate cancer patients, increased chemokine signaling IL8 and IL6 correlates with castrate-resistant prostate cancer (CRPC). IL8 and IL6 are produced by prostate epithelial cells and promote prostate cancer cell invasion; however, the mechanisms restraining prostate epithelial cell cytokine secretion are poorly understood. Herein, the cell-fate determinant factor DACH1 inhibited CRPC tumor growth in mice. Using Dach1(fl/fl)/Probasin-Cre bitransgenic mice, we show IL8 and IL6 secretion was altered by approximately 1,000-fold by endogenous Dach1. Endogenous Dach1 is shown to serve as a key endogenous restraint to prostate epithelial cell growth and restrains migration via CXCL signaling. DACH1 inhibited expression, transcription, and secretion of the CXCL genes (IL8 and IL6) by binding to their promoter regulatory regions in chromatin. DACH1 is thus a newly defined determinant of benign and malignant prostate epithelium cellular growth, migration, and cytokine abundance in vivo.

Chronic inflammatory mediators enhance prostate cancer development and progression

Chronic inflammation is postulated to influence prostate cancer progression. Preclinical studies have claimed that inflammatory mediators are involved in prostate cancer development and therefore suggested these as attractive targets for intervention. However, among the many pro-inflammatory mediators, there is no consensus regarding the identity of the primary one(s). In clinical studies, chronic inflammation has been found in prostate tumor specimens, and tissues resected for treatment of benign prostatic hyperplasia (BPH). Although collective evidence from molecular, experimental and clinical data suggests that inflammation can contribute or promote prostate carcinogenesis, an etiologic link has not yet been established. Moreover, the role of chronic inflammation in the onset of castration resistant and metastatic disease is unclear. Therefore it is important to open a dialog regarding recent findings on how chronic inflammatory mediators contribute to prostate cancer progression, and their usefulness to prevent disease progression. In this commentary, we assess the current literature with respect to chronic inflammation as a potential initiator and promoter of prostate carcinogenesis and discuss the prospects for its potential clinical applications.

Monocyte-Induced Prostate Cancer Cell Invasion is Mediated by Chemokine ligand 2 and Nuclear Factor-κB Activity

Study Background

The tumor microenvironment contains inflammatory cells which can influence cancer growth and progression; however the mediators of these effects vary with different cancer types. The mechanisms by which prostate cancer cells communicate with monocytes to promote cancer progression are incompletely understood. This study tested prostate cancer cell and monocyte interactions that lead to increased prostate cancer cell invasion.

Methods

We analyzed the prostate cancer cell invasion and NF-κB activity and cytokine expression during interaction with monocyte-lineage cells in co-cultures. The roles of monocyte chemotactic factor (MCP-1/CCL2) and NF-κB activity for co-culture induced prostate cancer invasion were tested. Clinical prostate cancer NF-κB expression was analyzed by immunohistochemistry.

Results

In co-cultures of prostate cancer cell lines with monocyte-lineage cells, (C-C motif) ligand 2 (CCL2) levels were significantly increased when compared with monocytes or cancer cells cultured alone. Prostate cancer cell invasion was induced by recombinant CCL2 in a dose dependent manner, similar to co-cultures with monocytes. The monocyte-induced prostate cancer cell invasion was inhibited by CCL2 neutralizing antibodies and by the CCR2 inhibitor, RS102895. Prostate cancer cell invasion and CCL2 expression induced in the co-cultures was inhibited by Lactacystin and Bay11-7082 NF-κB inhibitors. Prostate cancer cell NF-κB DNA binding activity depended on CCL2 dose and was inhibited by CCL2 neutralizing antibodies. Clinical prostate cancer NF-κB expression correlated with tumor grade.

Conclusions

Co-cultures with monocyte-lineage cell lines stimulated increased prostate cancer cell invasion through increased CCL2 expression and increased prostate cancer cell NF-κB activity. CCL2 and NF-κB may be useful therapeutic targets to interfere with inflammation-induced prostate cancer invasion.

The host microenvironment influences prostate cancer invasion, systemic spread, bone colonization, and osteoblastic metastasis

Prostate cancer (PCa) is the second leading cause of cancer death in men worldwide. Most PCa deaths are due to osteoblastic bone metastases. What triggers PCa metastasis to the bone and what causes osteoblastic lesions remain unanswered. A major contributor to PCa metastasis is the host microenvironment. Here, we address how the primary tumor microenvironment influences PCa metastasis via integrins, extracellular proteases, and transient epithelia-mesenchymal transition (EMT) to promote PCa progression, invasion, and metastasis. We discuss how the bone-microenvironment influences metastasis; where chemotactic cytokines favor bone homing, adhesion molecules promote colonization, and bone-derived signals induce osteoblastic lesions. Animal models that fully recapitulate human PCa progression from primary tumor to bone metastasis are needed to understand the PCa pathophysiology that leads to bone metastasis. Better delineation of the specific processes involved in PCa bone metastasize is needed to prevent or treat metastatic PCa. Therapeutic regimens that focus on the tumor microenvironment could add to the PCa pharmacopeia.

CC chemokine ligand 18 correlates with malignant progression of prostate cancer

Background and Aim. CC chemokine ligand 18 (CCL18) promotes malignant behaviors of various human cancer types. However, its involvement in human prostate cancer has not been fully elucidated. The aim of this study was to investigate the role of CCL18 in PCa. Methods. Expression of CCL18 at mRNA and protein levels was detected using real-time qRT-PCR and immunohistochemistry analysis. We analyzed the associations of CCL18 expression with clinical features of human PCa. The effects of PCa cell migration, invasion, and apoptosis were tested. The efficiency of CCL18 on prostate tumor growth was assessed in a subcutaneous xenograft model. Results. CCL18 expression was upregulated (both P < 0.01) in PCa tissues compared with those in noncancerous prostate tissues. CCL18 upregulation was correlated with high Gleason score (P = 0.034) of patients with PCa. rCCL18 stimulation in PCa cells promoted cell migration and invasion but decreased DU145 cells apoptosis rate. Furthermore, subcutaneous homografts models showed the increased tumor growth and tumor vascularization with the CCL18 stimulation, and the expression of Ki67, PCNA, and CD31 in CCL18 stimulation mice was also significantly increased. Conclusions. Our data offer the convincing evidence that the upregulation of CCL18 may be involved in the malignant progression of PCa.

Expression of CXC chemokine receptor-4 and forkhead box 3 in neuroblastoma cells and response to chemotherapy

Current evidence indicates that the abnormal expression of chemokines or their receptors, such as CXC chemokine receptor-4 (CXCR4), is positively correlated with the development, progression and metastasis of tumor cells. However, the role of CXCR4 in neuroblastoma and its response to chemotherapy remain largely unclear. In addition, forkhead box 3 (Foxp3), a transcription factor associated with T cell tolerance, is expressed in tumor cells and plays a role in the immune evasion of cancers. The present study aimed to examine the expression of CXCR4 and Foxp3 in the LAN-5 and SK-N-SH neuroblastoma cell lines. The effects of chemotherapy drugs, cyclophosphamide (CTX) and pirarubicin (THP), on the expression of these two genes were also investigated. Our findings indicated that CXCR4 and Foxp3 were highly expressed in LAN-5 and SK-N-SH cells. Following treatment with CTX and THP, the protein expression of CXCR4 in LAN-5 and SK-N-SH cells was significantly decreased (P<0.05). The expression of Foxp3 in LAN-5 cells was also significantly downregulated by CTX and THP treatment (P<0.05). Therefore, the high expression of CXCR4 and Foxp3 in LAN-5 and SK-N-SH cells and their subsequent downregulation following administration of the chemotherapy agents suggests that the chemokine receptors, CXCR4 and Foxp3, may be involved in the metastasis and tumor evasion of neuroblastoma. Further studies should investigate the expression of CXCR4 and Foxp3 in patient samples.

The osteoblastic and osteoclastic interactions in spinal metastases secondary to prostate cancer

Prostate cancer (PC) is one of the most common cancers arising in men and has a high propensity for bone metastasis, particularly to the spine. At this stage, it often causes severe morbidity due to pathological fracture and/or metastatic epidural spinal cord compression which, if untreated, inevitably leads to intractable pain, neurological deficit, and paralysis. Unfortunately, the underlying molecular mechanisms driving growth of secondary PC in the bony vertebral column remain largely unknown. Further investigation is warranted in order to identify therapeutic targets in the future. This review summarizes the current understanding of PC bone metastasis in the spine, highlighting interactions between key tumor and bone-derived factors which influence tumor progression, especially the functional roles of osteoblasts and osteoclasts in the bone microenvironment through their interactions with metastatic PC cells and the critical pathway RANK/RANKL/OPG in bone destruction.