ERK5 signalling in prostate cancer promotes an invasive phenotype.

BACKGROUND: Aberrant mitogen/extracellular signal-regulated kinase 5 (MEK5)-extracellular signal-regulated protein kinase 5 (ERK5)-mediated signalling has been implicated in a number of tumour types including prostate cancer (PCa). The molecular basis of ERK5-driven carcinogenesis and its clinical relevance remain to be fully characterised. METHODS: Modulation of ERK5 expression or function in human PCa PC3 and PC3-ERK5 (stably transfected with ERK5) cells was performed using siRNA-mediated knockdown or the MEK inhibitor PD18435 respectively. In vitro significance of ERK5 signalling was assessed by assays for proliferation, motility, invasion and invadopodia. Expression of matrix metalloproteinases/tissue inhibitors of metalloproteases was determined by Q-RT-PCR. Extracellular signal-regulated protein kinase 5 expression in primary and metastatic PCa was examined using immunohistochemistry. RESULTS: Reduction of ERK5 expression or signalling significantly inhibited the motility and invasive capability of PC3 cells. Extracellular signal-regulated protein kinase 5-mediated signalling significantly promoted formation of in vivo metastasis in an orthotopic PCa model (P<0.05). Invadopodia formation was also enhanced by forced ERK5 expression in PC3 cells. Furthermore, in metastatic PCa, nuclear ERK5 immunoreactivity was significantly upregulated when compared with benign prostatic hyperplasia and primary PCa (P=0.013 and P<0.0001, respectively). CONCLUSION: Our in vitro, in vivo and clinical data support an important role for the MEK5-ERK5 signalling pathway in invasive PCa, which represents a potential target for therapy in primary and metastatic PCa.

Identification of degradome components associated with prostate cancer progression by expression analysis of human prostatic tissues.

Extracellular proteases of the matrix metalloproteinase (MMP) and serine protease families participate in many aspects of tumour growth and metastasis. Using quantitative real-time RT-PCR analysis, we have undertaken a comprehensive survey of the expression of these enzymes and of their natural inhibitors in 44 cases of human prostate cancer and 23 benign prostate specimens. We found increased expression of MMP10, 15, 24, 25 and 26, urokinase plasminogen activator-receptor (uPAR) and plasminogen activator inhibitor-1 (PAI1), and the newly characterised serine proteases hepsin and matriptase-1 (MTSP1) in malignant tissue compared to benign prostate tissue. In contrast, there was significantly decreased expression of MMP2 and MMP23, maspin, and the protease inhibitors tissue inhibitor of metalloproteinase 3 (TIMP3), TIMP4 and RECK (reversion-inducing cysteine-rich protein with Kazal motifs) in the cancer specimens. The expression of MMP15 and MMP26 correlated positively with Gleason score, whereas TIMP3, TIMP4 and RECK expression correlated negatively with Gleason score. The cellular localisation of the expression of the deregulated genes was evaluated using primary malignant epithelial and stromal cell cultures derived from radical prostatectomy specimens. MMP10 and 25, hepsin, MTSP1 and maspin showed predominantly epithelial expression, whereas TIMP 3 and 4, RECK, MMP2 and 23, uPAR and PAI1 were produced primarily by stromal cells. These data provide the first comprehensive and quantitative analysis of the expression and localisation of MMPs and their inhibitors in human prostate cancer, leading to the identification of several genes involved in proteolysis as potential prognostic indicators, in particular hepsin, MTSP1, MMP26, PAI1, uPAR, MMP15, TIMP3, TIMP4, maspin and RECK.

Proteases in brain tumour progression.

Local invasion of tumour cells is characteristic of brain tumour progression. It is associated with increased motility and a potential to hydrolyse macromolecular components of the extracellular matrix. The peptidases that have been most investigated, and are induced during this process, are reviewed: the plasminogen activators (PAs), matrix metalloproteinases (MMPs) and lysosomal cysteine peptidases called cathepsins (Cats). Increased levels of urokinase-type PA (uPA) are observed mainly at the invasive margins of a tumour, whereas the data on the expression of tissue-type PA (tPA) are still controversial. It has been shown that the endogenous inhibitor of PAs, PAI-1, is localised in both tumour and tumour-associated endothelial cells. Among MMPs, the expression of the gelatinases, MMP2 and MMP9, strongly correlates with glioma progression. Membrane bound MT-MMPs, in particular MT1- and MT2-MMP, seem to play a major role in activating MMP-2. Several members of the ADAMTS family have also been detected in brain tumours, the most relevant being ADAMTS4, due to its cleavage of CNS specific proteins. Lysosomal cathepsin B is highly expressed in malignant glial cells and in endothelial cells of vascularised glioblastomas and is a predictor of a shorter survival. In addition to invasion, cathepsin L may play a role in decreased susceptibility of anaplastic glioma cells to apoptosis. Finally, cathepsin B was proposed as a marker for malignancy in the more aggressive type of meningiomas. Each of these peptidases may act alone, or in concert with the others, to support malignant behaviour of brain tumour cells; the development of new inhibitors of invasion, therefore, should contribute to the control of local spread of a tumour.

Epidermal growth factor and basic fibroblast growth factor increase the production of matrix metalloproteinases during in vitro decidualization of rat endometrial stromal cells.

Numerous growth factors are involved in mediating proliferation and differentiation of endometrial stromal cells during decidualization. During this period, the extracellular matrix of the endometrium undergoes extensive remodeling. We tested the hypothesis that epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta regulate expression of matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of metalloproteinases (TIMPs), during decidualization. Stromal cells were isolated from uteri hormonally sensitized to undergo decidualization and were cultured in the absence or presence of a growth factor. Using substrate-gel electrophoresis with gelatin as the substrate, we detected activity for gelatinase A and B, and collagenase-3, and using casein as a substrate, we detected activity for stromelysin-1. Increasing concentrations of EGF and bFGF resulted in increased activity of gelatinase B, collagenase-3, and stromelysin-1. Northern blot analyses revealed that EGF and bFGF also increased messenger RNA levels for these MMPs. There was no effect of these growth factors on gelatinase or TIMP-1, -2, and -3, nor was there an effect of transforming growth factor-beta on any MMP or TIMP examined. These data demonstrate that EGF and bFGF increase levels of proteolytic enzymes produced by endometrial stromal cells undergoing decidualization in vitro while having no effect on their inhibitors.

Gelatinases A and B and tissue inhibitors of metalloproteinases 1, 2, and 3 during in vivo and in vitro decidualization of rat endometrial stromal cells.

An important event during decidualization is the remodeling of the extracellular matrix, an event controlled by the balance of matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). A putative regulator of decidualization is prostaglandin E2 (PGE2). The present study shows that endometrial mRNA levels for TIMPs 1, 2, and 3 were increased while gelatinase A levels remained unchanged and gelatinase B levels decreased during oil-induced decidualization. The production of TIMPs 1, 2, and 3 and gelatinases A and B during in vitro decidualization was examined, as was the role of PGE2 as a regulator. Ovariectomized rats were given a regimen of estrogen and progesterone, which sensitized their uteri for decidualization, at which time endometrial stromal cells were isolated and cultured in serum-free conditions for 72 h. Northern blot analyses indicated the presence of the mRNAs for TIMPs and gelatinases, while reverse zymography and zymography showed the presence of their proteins. PGE2 decreased mRNA levels for TIMP-1 and gelatinase A but had no effect on gelatinase B or TIMPs 2 and 3. Indomethacin had no effect on any of the transcripts. These data indicate that rat endometrial stromal cells undergoing decidualization in vitro secrete gelatinases and TIMPs, and suggest that PGE2 may play a role in regulating tissue remodeling during decidualization.