Gabriella Proietti

Progenitor/Stem Cell Markers in Brain Adjacent to Glioblastoma: GD3 Ganglioside and NG2 Proteoglycan Expression

Characterization of tissue surrounding glioblastoma (GBM) is a focus for translational research because tumor recurrence invariably occurs in this area. We investigated the expression of the progenitor/stem cell markers GD3 ganglioside and NG2 proteoglycan in GBM, peritumor tissue (brain adjacent to tumor, BAT) and cancer stem-like cells (CSCs) isolated from GBM (GCSCs) and BAT (PCSCs). GD3 and NG2 immunohistochemistry was performed in paired GBM and BAT specimens from 40 patients. Double-immunofluorescence was carried out to characterize NG2-positive cells of vessel walls. GD3 and NG2 expression was investigated in GCSCs and PCSCs whose tumorigenicity was also evaluated in Scid/bg mice. GD3 and NG2 expression was higher in tumor tissue than in BAT. NG2 decreased as the distance from tumor margin increased, regardless of the tumor cell presence, whereas GD3 correlated with neoplastic infiltration. In BAT, NG2 was coexpressed with &agr;-smooth muscle actin (&agr;-SMA) in pericytes and with nestin in the endothelium. Higher levels of NG2 mRNA and protein were found in GCSCs while GD3 synthase was expressed at similar levels in the 2 CSC populations. PCSCs had lower tumorigenicity than GCSCs. These data suggest the possible involvement of GD3 and NG2 in pre/pro-tumorigenic events occurring in the complex microenvironment of the tissue surrounding GBM.

Soluble E-cadherin and IL-6 serum levels in patients affected by prostate cancer before and after prostatectomy

Prostate specific antigen (PSA) is still the best available tumour marker in prostate cancer (PCa), but presents some limits. Therefore, there is a need for novel markers in the detection and management of PCa. The 80-kDa soluble form of E-cadherin (sE-cad) and the cytokine IL-6 are being discussed as supplemental serum markers for PCa. In this study, sE-cad and IL-6 serum levels were determined in patients with pathological localized or locally advanced PCa without any previous treatment. These patients underwent radical retropubic prostatectomy (RRP) in accordance with the EAU Guidelines on Prostate Cancer. The molecules were determined via immunoenzymatic assays in samples collected before and after surgery. Statistical analysis was performed by Students t-test and Pearsons correlation test. sE-cad levels were 6.0 ± 2.7 and 4.6 ± 2.3 µg/ml, before and after RRP, respectively. A highly statistically significant decrease in sE-cad concentrations after RRP was observed (p<0.0001), in 50/61 patients (82%). sE-cad levels before and after surgery were correlated (Pearsons correlation coefficient, r=0.6993, p<0.0001). sE-cad values detected after surgery were higher in patients with PSA levels >10 ng/ml (p<0.05). sE-cad levels before RRP were significantly higher in patients with G3 tumours compared to those with G2 tumours (p<0.02). Finally, sE-cad concentrations both before and after surgery were higher in tumours with Gleason score =7 compared to those with Gleason score <7 (p<0.002 and p<0.05, respectively). Preliminary data from 20 patients indicated a statistically significant increase in IL-6 levels after RRP (11.2 vs. 7.2 pg/ml, p<0.001). This is the first study on the reduction in sE-cad levels after RRP in PCa patients. Moreover, it shows that preoperative sE-cad concentrations are higher in patients with less differentiated PCa. Promising findings of this pilot study may lead to investigation of sE-cad in a larger study with follow-up.

Analysis of angiogenesis related factors in glioblastoma, peritumoral tissue and their derived cancer stem cells

The formation of new blood vessels represents a crucial event under both physiological and pathological circumstances. In this study, we evaluated by immunohistochemistry, and/or Western blotting and/or quantitative real time-PCR the expression of HIF1α, HIF2α, VEGF, VEGFR1 and VEGFR2 in surgical glioblastoma multiforme (GBM) and peritumoral tissue samples obtained from 50 patients as well as in cancer stem cells (CSCs) isolated from GBM (GCSCs) and peritumoral tissue (PCSCs) of 5 patients. We also investigated the contribution of both GCSCs and PCSCs on the behavior of endothelial cells (ECs) in vitro. Immunohistochemistry demonstrated the expression of angiogenesis markers in both GBM and peritumoral tissue. In addition, in vitro tube formation assay indicated that both GCSCs and PCSCs stimulate EC proliferation as well as tube-like vessel formation. An increased migration aptitude was mainly observed when ECs were cultured in the presence of GCSCs rather than in the presence of PCSCs. These findings suggest that relevant neoangiogenetic events may occur in GBM. In particular, VEGF/VEGFR co-expression in PCSCs leads to hypothesize the involvement of an autocrine signaling. Moreover, our results suggest that both GCSCs and PCSCs own the skill of activating the “angiogenic switch” and the capability of modulating EC behavior, indicating that both cell types are either responsive to angiogenic stimuli or able to trigger angiogenic response. Together with our previous findings, this study adds a further piece to the challenging puzzle of the characterization of peritumoral tissue and of the definition of its real role in GBM pathophysiology.

Pivotal role of human stearoyl-CoA desaturases (SCD1 and 5) in breast cancer progression: oleic acid-based effect of SCD1 on cell migration and a novel pro-cell survival role for SCD5

The influence of cell membrane fluidity on cancer progression has been established in different solid tumors. We previously reported that “cancer-associated fibroblasts” (CAFs) induced epithelial-mesenchymal transition and increased cell membrane fluidity and migration in poorly (MCF-7) and highly invasive (MDA-MB-231) breast cancer cells. We also found that the membrane fluidity regulating enzyme stearoyl-CoA desaturase 1 (SCD1) was upregulated in tumor cells co-cultured with CAFs and established its essential role for both intrinsic and CAF-driven tumor cell motility. Here, we further explored the mechanisms involved in the SCD1-based modulation of breast cancer cell migration and investigated the role of the other human SCD isoform, SCD5. We showed that the addition of oleic acid, the main SCD1 product, nullified the inhibitory effects produced on MCF-7 and MDA-MB-231 cell migration by SCD1 depletion (pharmacological or siRNA-based). Conversely, SCD5 seemed not involved in the regulation of cancer cell motility. Interestingly, a clear induction of necrosis was observed as a result of the depletion of SCD5 in MCF-7 cells, where the expression of SCD5 was found to be upregulated by CAFs. The necrotic effect was rescued by a 48-h treatment of cells with oleic acid. These results provide further insights in understanding the role of SCD1 in both intrinsic and CAF-stimulated mammary tumor cell migration, unveiling the metabolic basis of this desaturase-triggered effect. Moreover, our data suggest the ability of CAFs to promote the maintenance of tumor cell survival by the induction of SCD5 levels.

Cancer stem cells from peritumoral tissue of glioblastoma multiforme: the possible missing link between tumor development and progression

In glioblastoma multiforme (GBM), cancer stem cells (CSCs) are thought to be responsible for gliomagenesis, resistance to treatment and recurrence. Unfortunately, the prognosis for GBM remains poor and recurrence frequently occurs in the peritumoral tissue within 2 cm from the tumor edge. In this area, a population of CSCs has been demonstrated which may recapitulate the tumor after surgical resection. In the present study, we aimed to characterize CSCs derived from both peritumoral tissue (PCSCs) and GBM (GCSCs) in order to deepen their significance in GBM development and progression. The stemness of PCSC/GCSC pairs obtained from four human GBM surgical specimens was investigated by comparing the expression of specific stem cell markers such as Nestin, Musashi-1 and SOX2. In addition, the growth rate, the ultrastructural features and the expression of other molecules such as c-Met, pMet and MAP kinases, involved in cell migration/invasion, maintenance of tumor stemness and/or resistance to treatments were evaluated. Since it has been recently demonstrated the involvement of the long non-coding RNAs (lncRNAs) in the progression of gliomas, the expression of H19 lncRNA, as well as of one of its two mature products miR-675-5p was evaluated in neurospheres. Our results show significant differences between GCSCs and PCSCs in terms of proliferation, ultrastructural peculiarities and, at a lower extent, stemness profile. These differences might be important in view of their potential role as a therapeutic target.

Characterization of inflammatory cell infiltrate of scleroderma skin: B cells and skin score progression

BackgroundThe purpose of this study was to investigate the frequency and the distribution of inflammatory cell infiltrate in two sets of cutaneous biopsies derived from clinically affected and unaffected skin in patients with systemic sclerosis (SSc) and to test correlation between the cell infiltrate and the progression of skin involvement.MethodsSkin was immunohistochemically assessed to identify CD68, CD3, CD20 and CD138-positive (+) cells in clinically affected and unaffected skin in 28 patients with SSc. Patients were followed for 6 months and the characteristics of the infiltrate were analyzed according to disease duration, clinical features and skin involvement progression.ResultsIn all SSc cutaneous specimens, cellular infiltrates were found in a perivascular location predominantly in the mid and deeper portions of the dermis. All the analyzed biopsies showed a CD3+ and CD68+ cell infiltrate and the mean number of CD3+ and of CD68+ cells was higher in clinically involved skin (CD3+, 71.7 ± 34.6 and CD68+, 26.3 ± 8.4, respectively) than in clinically uninvolved skin (CD3+, 45.7 ± 36.0 and CD68+, 13.6 ± 6.1, respectively) (p < 0.001 for both comparisons). CD20+ cells were found in 17 (60.7%) patients and in these patients the mean number of CD20+ cells was higher in clinically involved (4.7 ± 5.9) than in uninvolved skin (1.9 ± 2.9), (p = 0.04). There was a greater number of CD20+ cells in patients with early SSc compared with patients with long-standing disease. CD138+ cells were found in 100% of biopsies of clinically involved skin and in 89.3% of biopsies of uninvolved skin. The mean number of CD138+ cells was higher in clinically involved skin (3.6 ± 2.3) than in clinically uninvolved skin (1.9 ± 1.7), (p < 0.001). Seven patients experienced more than 20% worsening in the skin score after 6 months of follow up; all of them had a CD20+ skin infiltrate on biopsy of clinically involved skin.ConclusionsOur results confirm that mononuclear cells are present in the skin of all patients with SSc, underlining the role of inflammatory cell infiltrates in skin involvement in SSc. B cells in the skin seem to characterize patients with early diffuse skin disease and to correlate with skin progression.

Role of Stearoyl-CoA Desaturase 1 and 5 in breast cancer cell migration and survival

We previously reported that a major component of breast tumor stroma, the “cancer-associated fibroblasts” (CAFs), induced epithelial-mesenchymal transition and an increase in cell membrane fluidity as well as in migration speed and directness in poorly (MCF-7) and highly invasive (MDA-MB-231) breast cancer cells. We next investigated the mechanisms responsible for the CAF-promoted tumor cell migration demonstrating the crucial role of Stearoyl-CoA desaturase 1 (SCD1), one of the main enzyme regulating membrane fluidity. We found SCD1 to be upregulated in tumor cells co-cultured with CAFs and that its inhibition (pharmacological or siRNA-based) impaired both intrinsic and CAF-driven tumor cell migration. In the present study, we deepen the understanding of the mechanisms involved in the SCD1-based modulation of tumor cell migration, as well as the possible role of the other human SCD isoform, SCD5. Thus, in the two above mentioned cell lines we studied whether the inhibitory effect produced on cell migration by SCD1 depletion was due to the deficiency of oleic acid (OA), the main SCD1 enzymatic product. By a wound healing assay, we found that the addition of OA nullified the inhibitory effects produced on tumor cell migration by the SCD1 inhibition in both the cell lines while SCD5 appeared not to be involved in the regulation of their motility but it was upregulated in MCF-7 cells co-cultured with CAFs. Because of the high number of detached MCF-7 cells silenced for SCD5, we investigated the role of the desaturase on tumor cell survival and an induction of necrosis was found. Consistently with the promotion of tumor cell migration, CAFs have also been found to induce the activated form of the hepatocyte growth factor receptor, p-MET, in the two cell lines. These results provide further insights in understanding the role of SCD1 in both intrinsic and CAF-stimulated mammary tumor cell migration. Moreover, our data seem to suggest the ability of CAFs to promote the maintenance of tumor cell survival by the induction of SCD5 levels.

Cancer stem cells from peritumoral tissue of glioblastoma multiforme: the possible link between tumor development and progression

In glioblastoma multiforme (GBM), cancer stem cells (CSCs) are thought to be responsible for gliomagenesis, resistance to treatment and recurrence. Unfortunately, the prognosis for GBM remains poor and recurrence frequently occurs in the peritumoral tissue within 2 cm from the tumor edge. In this area, a population of CSCs has been demonstrated which may recapitulate the tumor after surgical resection. In the present study, we aimed to characterize CSCs derived from both peritumoral tissue (PCSCs) and GBM (GCSCs) in order to deepen their significance in GBM development and progression. The stemness of PCSC/GCSC couples obtained from four human GBM surgical specimens was investigated by comparing the expression of specific stem cell markers such as Nestin, Musashi-1 and SOX2. In addition, the growth rate, the ultrastructural features and the expression of other molecules such as c-Met, pMet and MAP kinases, involved in cell migration/invasion, maintenance of tumor stemness and/or resistance to treatments, were evaluated. Since it has been recently demonstrated the involvement of the long non-coding RNAs (lncRNAs) in the progression of gliomas, the expression of H19 lncRNA, as well as of one of its two mature products miR-675-5p, was assessed in neurospheres. Our results show significant differences between GCSCs and PCSCs in terms of proliferation, ultrastructural peculiarities and, at a lower extent, stemness profile. These differences might be important in view of their potential role as a therapeutic target.

Involvement of cancer stem cells in glioblastoma angiogenesis

It is widely accepted that glioblastoma (GBM) develops from cancer stem cells (CSCs), a subset of stem-like cells displaying high resistance to treatment. In fact, despite aggressive therapy, 90% of patients relapse within 2 cm from tumor edge. Our recent findings showed the existence of a CSC type, residing in GBM peritumor tissue (PCSCs), that bears distinct characteristics from CSCs of the tumor mass (GCSCs). It should be considered the possibility that, after surgical resection, PCSCs might represent a reservoir of cells able to recapitulate the tumor. In this setting, characterization of PCSCs appears to be crucial in order to identify novel effective therapeutic targets. Thus, our aim was to investigate GCSCs and PCSCs role in angiogenesis, a key event in both GBM and peritumor tissue, whose vasculature shows features similar to those found in the tumor mass. In particular, we analyzed, by immunocytochemistry (ICC), Western blotting or real-time PCR, the expression of molecules involved in hypoxia and angiogenesis, such as HIF1α, HIF2α, and VEGF along with its receptors (VEGFR1, VEGFR2). ICC has highlighted the presence and the specific localization of these molecules in both GCSCs and PCSCs. The two cell populations showed comparable levels of VEGF. The transcript of VEGFR1 was in general expressed at higher levels in GCSCs than in PCSCs, while VEGFR2 mRNA and protein did not show a unique trend of expression. The expression of VEGF and its receptors in both GCSCs and PCSCs suggests that, besides well-known paracrine loops, autocrine signalings are also involved in tumor angiogenesis. Moreover, the expression of angiogenesis markers in PCSCs suggests these cells to have a direct role in peritumor tissue new vessel formation. In this regard, PCSCs should be considered a promising therapeutic target to counteract the angiogenesis-supported tumor progression.

Relevance of tumor surrounding area in chemoresistance of glioblastoma(GBM)

The mechanisms responsible for resistance to damage in normal cells might determine chemoresistance in both tumor cells and cancer stem cells (CSC). Relapse due to chemoresistant residual disease is a major cause of death in GBM. Increasing body of evidence indicates that not only tumor area (TT), but also tissue surrounding the tumor border (pTT) of GBM contains tumor cells and CSC, which could contribute to the disease progression. Therefore, the need to have a deeper insight in this area through identification of the characteristics that confer chemoresistance. In this study, the expression of molecules involved in chemoresistance was investigated in samples derived from TT and from pTT at <1 cm from the tumor border, in 40 patients with GBM. The expression of O6-methylguanine-DNA methyltransferase (MGMT), a suicidal DNA repair protein; Breast Cancer Resistance Protein (BCRP1), a drug efflux transporter, and A2B5 (c-series gangliosides) has been determined by immunohistochemistry. The percentage of MGMT positive cells was higher (p<0.0001, paired Student’s t test) in pTT (median: 53.5, range: 0.6-92.4) with respect to TT (median: 3.3, range: 0.0-70.7). The same trend was observed in BCRP1 expression (p<0.02; pTT, median: 27.6, range: 1.0-95.6; TT, median: 10.1, range: 0.2-72.1). No difference was found between pTT and TT in A2B5 expression (p=0.69, pTT, median: 29.8, range: 0.0-98.4; TT, median: 26.0, range: 0.0-96.8). Patients were then divided into two groups according to presence (group A) or absence (group B) of tumor cells in pTT. The trend previous observed in MGMT expression was maintained in both groups, while only in group A a statistically significant difference in BCRP1 expression was observed. Our results confirm that the tissue surrounding GBM is not a normal tissue, and that it represents a frontline of tumor invasion, particularly for the presence of some molecules involved in chemoresistance, which could explain the disease recurrence after the conventional treatment of GBM. Experiments about the expression of above mentioned molecules in CSC from pTT and TT are in progress. Supported by FIRB, ACCORDI DI PROGRAMMA 2010