Interactions of human prostatic epithelial cells with bone marrow endothelium: binding and invasion

Abstract

The second commonest cause of cancer death in the Western world is attributed to prostate cancer (Jensen et al, 1990). It is well documented that prostatic carcinoma shows a predilection to metastasize to the bone marrow (Jacobs, 1983). Metastatic prostate cancer remains an incurable disease and as such, is a massive clinical problem. There is clearly a need to elucidate the factors underlying the spread of prostate cancer, particularly to the skeleton.It has been suggested that the bone marrow microenvironment is conducive to the growth of prostate cancer cells, which nonselectively enter the bone marrow from the circulation (Galasko, 1981;Jacobs, 1983;Paget, 1989;Body, 1992). However, the strikingly consistent pattern of prostate metastasis within the red marrow suggests that this process may in fact be regulated (Fidler et al, 1978). The mechanism of metastasis is a complex multi-step process that is not fully understood. One critical step in this mechanism may be the attachment to and extravasation through endothelial barriers by malignant cells possibly leading to selective metastatic sites. Tumour cell binding to endothelium involves two distinct steps, an initial docking step mediated via lectin-carbohydrate interactions followed by an integrin-mediated locking step (Honn and Tang, 1992). Several endothelial and tumour adhesion molecules have been associated with metastasis. In particular the integrins β1, α2 and α5 have been shown to be expressed by prostate epithelial cells and bone marrow cells (Soligo et al, 1990;Nagle et al, 1994;Rokhlin and Cohen, 1995). The carbohydrate sialyl Lewis X has also been associated with breast and lung cancer metastasis and its ligand P selectin is found on endothelial cells (Soligo et al, 1990). Some lung, brain, liver and ovary metastatic tumour cells have been demonstrated to bind selectively to endothelial cells isolated from lung, brain, liver and ovary respectively (Nicolson and Winkelhake, 1975;Auerbach et al, 1987). These studies suggest an active regulatory role for the endothelium in metastasis (Zetter, 1990).We have shown previously that primary prostatic epithelia from both benign and malignant tissue show an accelerated growth rate within bone marrow stroma compared to control stroma (Lang et al, 1998) and also that integrin α2β1 is a major contributor to the binding of primary prostatic epithelial cells to bone marrow stroma (Lang et al, 1997). This pattern of primary prostatic epithelial cell adhesion (α2β1) is mimicked by the prostate cell line, PC3 (Kostenuik et al, 1996) and our experiments were therefore conducted with this cell line. These studies have now been extended to develop a model to investigate the interactions of prostatic epithelial cells (primary and cell lines) with the bone marrow endothelium. MATERIALS AND METHODS MaterialsGeneral chemicals were purchased from Sigma (Poole, UK). Tissue culture media and supplements were obtained from Gibco Summary Prostate cancer shows a propensity to form secondary tumours within the bone marrow. Such ...

Invasive characteristics of human prostatic epithelial cells: understanding the metastatic process

“…To examine this phenomenon more closely, with particular reference to binding and invasion, we used the GFP-transfected PC-3 cell line in conjunction with BMEC using confocal microscopy. We found that most of the PC3-GFP cells bound within 60 min and further to Scott et al (2001), we found that they had a marked tendency to bind at endothelial junctional regions (86.2677.12%; P ¼ 0.003). Figure 1A shows three PC3-GFP cells at their binding sites after 60 min in contact with the BMEC.…”

“…We have previously developed models allowing the study of the interactions between malignant prostate epithelial cells and endothelial or BMS layers (Lang et al, 1997(Lang et al, , 1998Scott et al, 2001). We have developed these models to target the blood/BMS endothelial barrier specifically, thereby allowing the visualisation not just of the sites of binding but also of the prostate epithelial invasive process.…”

“…Previously, Scott et al (2001) found that CaP cells bind to BMS and bone marrow endothelial primary cells (BME) in preference to TCP, human umbilical vein endothelial cell line (HUVEC) and prostate fibroblasts. To examine this phenomenon more closely, with particular reference to binding and invasion, we used the GFP-transfected PC-3 cell line in conjunction with BMEC using confocal microscopy.…”

“…Initial steps include the loss of cell-to-cell adhesion within the tumour by downregulation of molecular binding complexes such as the E-cadherin/b-catenin complex (Umbas et al, 1997;Bryden et al, 2002) and intravasation of tumour cells through the basement membrane by production of enzymes such as matrix metalloproteinases (Hart et al, 2002). Once in the peripheral blood, the circulating tumour cell has to bind at its preferred metastatic site and invade through the local endothelial barrier to gain access to the underlying stroma (Scott et al, 2001) where it can then become established (Lang et al, 1997(Lang et al, , 1998. We have shown previously that prostate epithelial cells preferentially bind to bone marrow endothelial cells in an integrin b1-dependent manner, and that only malignant prostate epithelial cells invade in response to bone marrow endothelial cells (Scott et al, 2001).…”

“…Once in the peripheral blood, the circulating tumour cell has to bind at its preferred metastatic site and invade through the local endothelial barrier to gain access to the underlying stroma (Scott et al, 2001) where it can then become established (Lang et al, 1997(Lang et al, , 1998. We have shown previously that prostate epithelial cells preferentially bind to bone marrow endothelial cells in an integrin b1-dependent manner, and that only malignant prostate epithelial cells invade in response to bone marrow endothelial cells (Scott et al, 2001). However, the specific mechanisms of invasion through the bone marrow endothelial barrier and the stimuli for that invasion are as yet undefined.…”