Breast cancer carcinoma-associated fibroblasts differ from breast fibroblasts in immunological and extracellular matrix regulating pathways.

Tumor stroma has been recently shown to play a crucial role in the development of breast cancer. Since the origin of the stromal cells in the tumor is unknown, we have examined differences and similarities between three stromal cell types of mesenchymal origin, namely carcinoma associated fibroblasts from breast tumor (CAFs), fibroblasts from normal breast area (NFs) and bone marrow derived mesenchymal stromal cells (MSCs). In a microarray analysis, immunological, developmental and extracellular matrix -related pathways were over-represented in CAFs when compared to NFs (p<0.001). Under hypoxic conditions, the expression levels of pyruvate dehydrogenase kinase-1 (PDK1) and pyruvate dehydrogenase kinase-4 (PDK4) were lower in CAFs when compared to NFs (fold changes 0.6 and 0.4, respectively). In normoxia, when compared to NFs, CAFs displayed increased expression of glucose transporter 1 (GLUT-1) and PDK1 (fold changes 1.5 and 1.3, respectively). With respect to the assessed surface markers, only CD105 was expressed differently in MSCs when compared to fibroblasts, being more often expressed on MSCs. Cells with myofibroblast features were present in both NF and CAF samples. We conclude, that CAFs differ distinctly from NFs at the gene expression level, this hypothesis was also tested in silico for other available gene expression data.

Tumor tissue inhibitor of metalloproteinases-1 (TIMP-1) in hormone-independent breast cancer might originate in stromal cells, and improves stratification of prognosis together with nodal status.

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is shown to be a potential marker for poor prognosis in breast cancer, but the biology of TIMP-1 is only partially understood. In this study, TIMP-1 production was studied in a co-culture model of hormone-independent breast cancer cell lines and mesenchymal stem cells mimicking the stromal components of the tumor. In addition, the prognostic value of TIMP-1 was histologically evaluated in a clinical material of 168 patients with hormone-independent breast tumors. The hormone-independent breast cancer (BC) cell lines MDA-MB-231, M4A4 and NM2C5 did not produce TIMP-1 protein in measureable quantities. Six tested primary mesenchymal stem cell lines all produced TIMP-1. Co-culturing of mesenchymal stem cells and breast cancer cells resulted in positive immunocytochemical diffuse staining for TIMP-1 for both cell types. Culturing breast cancer cells with MSC-conditioned media resulted in a positive cytoplasmic immunoreactivity for TIMP-1, and TIMP-1 protein concentration in cell lysates increased 2.7-fold (range 1.1-4.7). The TIMP-1 mRNA levels remained unaffected in BC cells. This might suggest that breast cancer cells can take up TIMP-1 produced by stromal cells and are thus displaying cellular immunoreactivity. In addition, TIMP-1 was shown to improve stratification of prognosis in clinical material.

Toll-like receptor 9 ligands enhance mesenchymal stem cell invasion and expression of matrix metalloprotease-13.

Human mesenchymal stem cells (hMSCs) are multipotent cells that are found in the bone marrow. Inflammation and tissue damage mobilize MSCs and induce their migration towards the damaged site through mechanisms that are not well defined. Toll-like receptor-9 (TLR9) is a cellular receptor for microbial and vertebrate DNA. Stimulation of TLR9 induces inflammatory and invasive responses in TLR9-expressing cells. We studied here the expression of TLR9 in human MSCs and the effects of synthetic TLR9-agonists on their invasion. Constitutive expression of TLR9 was detected in human MSCs but the expression was suppressed when MSCs were induced to differentiate into osteoblasts. Using standard invasion assays and a novel organotypic culture model based on human myoma tissue, we discovered that stimulation with the TLR9 agonistic, CpG oligonucleotides increased the invasion capacity of undifferentiated MSCs. Simultaneously, an increase in MMP-13 synthesis and activity was detected in the CpG-activated MSCs. Addition of anti-MMP-13 antibody significantly diminished the CpG-induced hMSC invasion. We conclude that treatment with TLR9-ligands increases MSC invasiveness, and this process is at least partially MMP-13-mediated.

High serum TIMP-1 correlates with poor prognosis in breast carcinoma - a validation study.

A number of studies have demonstrated that high tumor tissue levels of tissue inhibitor of metalloproteinases-1 (TIMP-1) are associated with a poor prognosis in breast cancer, suggesting that TIMP-1 could be a valid prognostic marker in this disease. Recently, our laboratories have presented results showing that TIMP-1 also carries prognostic information when measured in serum. This is an important finding, since serum is a much more preferable material compared with tumor tissue extracts. The aim of the present study was to validate the previous results concerning the prognostic value of TIMP-1 in serum obtained preoperatively from 68 patients with primary breast cancer. This was done by measuring the same serum samples as in the previous study but in a different laboratory using a different ELISA assay. We confirmed that patients with the highest serum levels of TIMP-1 (> 197.7 ng/ml) had significantly shorter disease-specific survival compared with patients with low serum TIMP-1 levels. In the group of node-negative patients, 53% of the patients with high levels of TIMP-1 survived after 10 years of follow-up compared to 92% of the patients with low levels. This study thus confirms the reproducibility across laboratories of the results concerning the prognostic value of TIMP-1 in serum. We also investigated whether measurements of the specific fraction of uncomplexed TIMP-1 improved the prognostic value of TIMP-1 in serum, as has been shown to be the case for tumor tissue extracts. However, including information of the level of uncomplexed TIMP-1 did not seem to provide additional prognostic information to that already provided by total TIMP-1.