α-Trinositol inhibits FGF-stimulated growth of smooth muscle and breast cancer cells

FGF-8b induces growth and rich vascularization in an orthotopic PC-3 model of prostate cancer

Fibroblast growth factor 8 (FGF-8) is expressed at an increased level in a high proportion of prostate cancers and it is associated with a poor prognosis of the disease. Our aim was to study the effects of FGF-8b on proliferation of PC-3 prostate cancer cells and growth of PC-3 tumors, and to identify FGF-8b-associated molecular targets. Expression of ectopic FGF-8b in PC-3 cells caused a 1.5-fold increase in cell proliferation in vitro and a four- to fivefold increase in the size of subcutaneous and orthotopic prostate tumors in nude mice. Tumors expressing FGF-8b showed a characteristic morphology with a very rich network of capillaries. This was associated with increased spread of the cancer cells to the lungs as measured by RT-qPCR of FGF-8b mRNA. Microarray analyses revealed significantly altered, up- and downregulated, genes in PC-3 cell cultures (169 genes) and in orthotopic PC-3 tumors (61 genes). IPA network analysis of the upregulated genes showed the strongest association with development, cell proliferation (CRIP1, SHC1), angiogenesis (CCL2, DDAH2), bone metastasis (SPP1), cell-to-cell signaling and energy production, and the downregulated genes associated with differentiation (DKK-1, VDR) and cell death (CYCS). The changes in gene expression were confirmed by RT-qPCR. In conclusion, our results demonstrate that FGF-8b increases the growth and angiogenesis of orthotopic prostate tumors. The associated gene expression signature suggests potential mediators for FGF-8b actions on prostate cancer progression and metastasis.

Regulation of osteoblast differentiation: a novel function for fibroblast growth factor 8

Several members of the fibroblast growth factor (FGF) family have an important role in the development of skeletal tissues. FGF-8 is widely expressed in the developing skeleton, but its function there has remained unknown. We asked in this study whether FGF-8 could have a role in the differentiation of mesenchymal stem cells to an osteoblastic lineage. Addition of FGF-8 to mouse bone marrow cultures effectively increased initial cell proliferation as well as subsequent osteoblast-specific alkaline phosphatase production, bone nodule formation, and calcium accumulation if it was added to the cultures at an early stage of osteoblastic differentiation. Exogenous FGF-8 also stimulated the proliferation of MG63 osteosarcoma cells, which was blocked by a neutralizing antibody to FGF-8b. In addition, the heparin-binding growth factor fraction of Shionogi 115 (S115) mouse breast cancer cells, which express and secrete FGF-8 at a very high level, had an effect in bone marrow cultures similar to that of exogenous FGF-8. Interestingly, experimental nude mouse tumors of S115 cells present ectopic bone and cartilage formation as demonstrated by typical histology and expression of markers specific for cartilage (type II and IX collagen) and bone (osteocalcin). These results demonstrate that FGF-8 effectively predetermines bone marrow cells to differentiate to osteoblasts and increases bone formation in vitro. It is possible that FGF-8 also stimulates bone formation in vivo. The results suggest that FGF-8, which is expressed by a great proportion of malignant breast and prostate tumors, may, among other factors, also be involved in the formation of osteosclerotic bone metastases.