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Glioblastoma (GBM) is a lethal cancer characterized by florid vascularization and aberrantly elevated VEGF. Antiangiogenic therapy with VEGF antibody reduces GBM tumor growth. However, the clinical benefits are transient and invariably followed by tumor recurrence. Recently, it has been demonstrated that in glioblastoma (GBM), cancer stem cells (CSCs) are responsible for either tumorigenesis or neoangiogenesis. In particular, a fraction of CSCs is represented by a population of endothelial progenitors. In our previous studies, we showed the presence of nestin+ cell and nestin+ and endoglin (CD105) + vasculature, not only in the GBM but also in the tissue surrounding the tumor, suggesting the involvement of CSC in endothelial differentiation also in peritumor tissue. In this study, with the aim to understand CSCs involvement in angiogenesis, we investigated the expression of angiogenesis markers (VEGF, VEGFR1, VEGFR2, HIF1α and HIF2α) by immunocytochemistry, western blot or RT- PCR analyisis, in CSCs derived from GBM (GCSC) and peritumor tissue (PCSC) of 4 patients. Both GCSCs and PCSCs were immunopositive for HIF1α and HIF2α, VEGF and its receptors VEGFR1 and VEGFR2, which underline the presence of autocrine and paracrine growth factor loops. Immunoblotting showed that VEGF is expressed at higher levels in GCSCs than PCSCs, with the exception of a patient who showed an up-regulation in PCSCs. Moreover, real time PCR showed that both VEGFR1 and VEGFR2 were expressed at low level in the two types of CSCs with a down-regulation of VEGFR1 in PCSCs. These results indicate the presence of all angiogenic markers in PCSCs suggesting their involvement in the GBM local recurrence. The inhibition of multiple angiogenic pathways may be a new line of attack on this deadly cancer.

Interactions occurring between malignant cells and stromal microenvi-ronment greatly influence progression of breast cancer. In a previous study, we co-cultured mammary cancer cells exhibiting different degrees of metastatic potential (MDA-MB-231>MCF-7) with fibroblasts isolated from breast healthy skin (normal fibroblasts, NFs) or breast tumor stroma (cancer-associated fibroblasts, CAFs). In this system, we demonstrated the influence exerted in particular by CAFs on malignant cells, leading to the acquisition of a more aggressive/invasive phenotype (i.e. reduced adhesion, epithelial-mesenchymal transition, enhanced plasma membrane fluidity and migration velocity/directness). In the present study, we evaluated the reciprocal effect of breast tumor cells and fibroblasts in co-culture on the expression of the main enzyme regulating the fatty acids membrane composition, Stearoyl-CoA desaturase 1 (SCD1). Abnormally high levels of SCD1 have been reported in different cancers and transformed cells and the enzyme has been recently raised to the role of key regulator of cell growth, programmed cell death and car-cinogenesis. In our experience, Western blot analysis demonstrated a strong increase in SCD1 expression in both MCF-7 and MDA-MB-231 cells, resulting from their interaction with CAFs and, at a lesser extent, with NFs. High levels of SCD1 were also observed in both NFs and CAFs when co-cultured with MCF-7 cells. MDA-MB-231 cells more slightly up-regulated the enzyme expression in NFs or even induced a certain inhi-bition in CAFs. The fibroblast-triggered up-regulation of SCD1 in cancer cells could rea-sonably be considered the molecular event underlying the increase of membrane fluidity, previously observed in tumor cells co-cultured with NFs and, notably, with CAFs. This change might downstream promote the pre-viously described increase in tumor cell motility.

Interactions occurring between malignant cells and stromal microenvi-ronment greatly influence progression of breast cancer. In a previous study, we co-cultured mammary cancer cells exhibiting different degrees of metastatic potential (MDA-MB-231>MCF-7) with fibroblasts isolated from breast healthy skin (normal fibroblasts, NFs) or breast tumor stroma (cancer-associated fibroblasts, CAFs). In this system, we demonstrated the influence exerted in particular by CAFs on malignant cells, leading to the acquisition of a more aggressive/invasive phenotype (i.e. reduced adhesion, epithelial-mesenchymal transition, enhanced plasma membrane fluidity and migration velocity/directness). In the present study, we evaluated the reciprocal effect of breast tumor cells and fibroblasts in co-culture on the expression of the main enzyme regulating the fatty acids membrane composition, Stearoyl-CoA desaturase 1 (SCD1). Abnormally high levels of SCD1 have been reported in different cancers and transformed cells and the enzyme has been recently raised to the role of key regulator of cell growth, programmed cell death and car-cinogenesis. In our experience, Western blot analysis demonstrated a strong increase in SCD1 expression in both MCF-7 and MDA-MB-231 cells, resulting from their interaction with CAFs and, at a lesser extent, with NFs. High levels of SCD1 were also observed in both NFs and CAFs when co-cultured with MCF-7 cells. MDA-MB-231 cells more slightly up-regulated the enzyme expression in NFs or even induced a certain inhi-bition in CAFs. The fibroblast-triggered up-regulation of SCD1 in cancer cells could rea-sonably be considered the molecular event underlying the increase of membrane fluidity, previously observed in tumor cells co-cultured with NFs and, notably, with CAFs. This change might downstream promote the pre-viously described increase in tumor cell motility.