Stromal factors involved in prostate carcinoma metastasis to bone

BACKGROUND Prostate carcinoma (PC) frequently metastasizes to bone, where it causes significant morbidity and mortality. Stromal elements in the primary and metastatic target organs are important mediators of tumor cell intravasation, chemoattraction, adhesion to target organ microvascular endothelium, extravasation, and growth at the metastatic site. METHODS The role of stromal factors in bone metastasis was determined with a cyclic DNA microarray comparison of a bone‐derived cell PC cell line with a soft tissue‐derived cell PC cell line and by evaluating the effects of selected stromal components on PC cell chemotaxis, cell adhesion to human bone marrow endothelium (HBME), and PC cell growth. RESULTS The authors demonstrate that PC cells express protease‐activated receptor 1 (PAR1; thrombin receptor), and its expression is up‐regulated in PC compared with normal prostate tissue. In addition, this overexpression was very pronounced in bone‐derived PC cell lines (VCaP and PC‐3) compared with soft tissue PC cell lines (DUCaP, DU145, and LNCaP). The authors report that bone stromal factors, including stromal cell‐derived factor 1 (SDF‐1) and collagen Type I peptides, are chemoattractants for PC cells, and they demonstrate that some of these factors (e.g., extracellular matrix components, transforming growth factor β, bone morphogenic proteins [BMPs], and SDF‐1) significantly alter PC‐HBME interaction in vitro. Finally, stromal factors, such as BMPs, can regulate the proliferation of PC cells in vitro. CONCLUSIONS Soluble and insoluble elements of the stroma are involved in multiple steps of PC metastasis to bone. The authors hypothesize that PAR1 may play a central role in prostate tumorigenesis. Cancer 2003;97(3 Suppl):739–47. © 2003 American Cancer Society. DOI 10.1002/cncr.11181 The authors present data supporting the role of stromal factors in the metastasis of prostate carcinoma to bone marrow. Stromal factors can regulate local tumor cell invasion, act as chemoattractants, modulate tumor cell adhesion to bone marrow endothelium, facilitate extravasation, and regulate tumor cell growth in the bone microenvironment.