Advanced prostate cancer: reinforcing the strings between inflammation and the metastatic behavior.

It is currently estimated that inflammatory responses are linked to 15-20% of all deaths from cancer worldwide. Although many studies point to an important role of inflammation in prostate growth, the contribution of inflammation to castration-resistant prostate cancer is not completely understood. The presence of inflammatory mediators in tumor microenvironment raises the question whether genetic events that participate in cancer development and progression are responsible for the inflammatory milieu inside and surrounding tumors. Activated oncogenes, cytokines, chemokines and their receptors, sustained oxidative stress and antioxidant imbalance share the capacity to orchestrate these pro-inflammatory programs; however, the diversity of the inflammatory cell components will determine the final response in the prostate tissue. These observations give rise to the concept that early genetic events generate an inflammatory microenvironment promoting prostate cancer progression and creating a continuous loop that stimulates a more aggressive stage. It is imperative to dissect the molecular pathologic mechanism of inflammation involved in the generation of the castration-resistant phenotype in prostate cancer. Here, we present a hypothesis where molecular signaling triggered by inflammatory mediators may evolve in prostate cancer progression. Thus, treatment of chronic inflammation may represent an important therapeutic target in advanced prostate cancer.

Heme oxygenase 1 (HO-1) challenges the angiogenic switch in prostate cancer.

Prostate cancer (PCa) is the second leading cause of cancer-associated death in men. Once a tumor is established it may attain further characteristics via mutations or hypoxia, which stimulate new blood vessels. Angiogenesis is a hallmark in the pathogenesis of cancer and inflammatory diseases that may predispose to cancer. Heme oxygenase-1 (HO-1) counteracts oxidative and inflammatory damage and was previously reported to play a key role in prostate carcinogenesis. To gain insight into the anti-tumoral properties of HO-1, we investigated its capability to modulate PCa associated-angiogenesis. In the present study, we identified in PC3 cells a set of inflammatory and pro-angiogenic genes down-regulated in response to HO-1 overexpression, in particular VEGFA, VEGFC, HIF1α and α5ß1 integrin. Our results indicated that HO-1 counteracts oxidative imbalance reducing ROS levels. An in vivo angiogenic assay showed that intradermal inoculation of PC3 cells stable transfected with HO-1 (PC3HO-1) generated tumours less vascularised than controls, with decreased microvessel density and reduced CD34 and MMP9 positive staining. Interestingly, longer term grown PC3HO-1 xenografts displayed reduced neovascularization with the subsequent down-regulation of VEGFR2 expression. Additionally, HO-1 repressed nuclear factor κB (NF-κB)-mediated transcription from an NF-κB responsive luciferase reporter construct, which strongly suggests that HO-1 may regulate angiogenesis through this pathway. Taken together, these data supports a key role of HO-1 as a modulator of the angiogenic switch in prostate carcinogenesis ascertaining it as a logical target for intervention therapy.

Key questions in metastasis: new insights in molecular pathways and therapeutic implications.

The metastatic cascade and colonization remains a major challenge in clinical therapeutics. The formation of metastasis has many rate limiting steps. The expression of metastases initiation genes in primary tumors is driven by the need for cell motility, invasiveness, handling the shear stress in the vasculature and lymphatic circulation, and the survival and persistent growth in the distant organ. However, the expression of the progression genes in the primary tumors has a more complex basis. These metastasis-prone genes support primary tumor growth through one particular effect, whereas they enhance distant metastasis through another effect. The boundaries between metastasis initiation and metastasis progression genes are not rigid. In this review, we examine novel gene signatures identified in metastases, address key inflammatory factors mastering homing selection, gain further mechanistic insights into cell plasticity and evaluate the role of microRNAs. Moreover, we also describe the recent progress in developing nanoparticle imaging substantiating a promising theranostic platform for future cancer diagnostics and treatment, and assess the relevance of the bioinformatic analysis of metastasis-related proteins with an eye toward the metastatic niche. All these tools will provide valuable biological information of the progression of the disease, helping find potential therapeutic targets and improving surgical procedures. In a near future the understanding of the molecular mechanisms in tumor dissemination will be pivotal for the translation of these methods to the clinic and will help to overcome the barriers in clinical therapy of metastases.