Mast cells affect growth in various humanCancer growth is dependent on the reciprocal interaction between tumor cells and their microenvironment. Cancerassociated fibroblasts, 1 vascular cells, and inflammatory cells such as macrophages [2][3][4] have been shown to promote prostate tumor growth. Mast cells are also of importance for tumor growth and have been shown to affect angiogenesis 5-7 but are also potent regulators of inflammation and thus their specific function during tumor progression is complex and shows significant plasticity. 8 -10 Their role in prostate cancer (PC) in patients was recently explored in two separate studies using tryptase and c-Kit as markers for mast cells. These studies lacked the discrepancy between intra-and peritumoral mast cells and did not identify mast cells as independent prognostic variables. One of the studies showed that tryptase-positive mast cells were related to poor outcome in PC patients. 12 The other study analyzed c-Kit-positive cells in tumor samples from PC patients and found an association between increased mast cell numbers and a favorable prognosis. 13Castration therapy is the gold standard for treatment of patients with metastatic PC, but in the majority of cases the formation of castrate-resistant prostate tumors is inevitable. The mechanisms behind the relapse are not fully understood but could be related to changes in the androgen receptor and the tumor stroma.

TINT changes could probably, when more rigorously defined and validated, be used to diagnose and prognosticate prostate cancer.

Tumor-associated macrophages are involved in angiogenesis and tumor progression, but their role and specific site of action in prostate cancer remain unknown. To explore this, Dunning R-3327 AT-1 rat prostate tumor cells were injected into the prostate of syngenic and immunocompetent Copenhagen rats and analyzed at different time points for vascular proliferation and macrophage density. Endothelial proliferation increased with tumor size both in the tumor and importantly also in the extratumoral normal prostate tissue. Macrophages accumulated in the tumor and in the extratumoral normal prostate tissue and were most abundant in the invasive zone. Moreover, only extratumoral macrophages showed strong positive associations with tumor size and extratumoral vascular proliferation. Treatment with clodronate-encapsulated liposomes reduced the monocyte/macrophage infiltration and resulted in a significant inhibition of tumor growth. This was accompanied by a suppressed proliferation in microvessels and in the extratumoral prostate tissue also in arterioles and venules. The AT-1 tumors produced, as examined by RT(2) Profiler PCR arrays, numerous factors promoting monocyte recruitment, angiogenesis, and tissue remodeling. Several, namely, chemokine (C-C) ligand 2, fibroblast growth factor 2, matrix metalloproteinase 9, interleukin 1beta, interferon gamma, and transforming growth factor beta, were highly upregulated by the tumor in vivo compared with tumor cells in vitro, suggesting macrophages as a plausible source. In conclusion, we here show the importance of extratumoral monocytes/macrophages for prostate tumor growth, angiogenesis, and extratumoral arteriogenesis. Our findings identify tumor-associated macrophages and several chemotactic and angiogenic factors as potential targets for prostate cancer therapy.

Androgen-independent tumor cell respond to castration when growing in an androgen-dependent environment. The presence of a tumor influences the castration response in the surrounding normal tissue. The microenvironment determines how prostate epithelial cells respond to castration.