Pathologica 4-07.pdf - Pacini Editore

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Immunophenotipical characterization of
targeted dendritic cell vacciantion to
glioblastoma derived cancer stem cell
P.L. Poliani, S. Pellegatta * , M. Ravanini, G. Finocchiaro * ,
F. Facchetti
Department of Pathology, University of Brescia, Italy; * Department
of Experimental Neuro-Oncology, National Neurological
Istitute “C. Besta”, Milan, Italy
Introduction. A novel intriguing scenario in tumor biology
implies that only a subgroup of cells is endowed with properties
that are necessary to perpetuate tumor growth. These
cells would recapitulate the role of progenitor stem cells during
development and the neoplastic phenotype would then be
the result of aberrant organogenesis. The presence of cancer
stem-like cells (CSC) has been proposed in leukemias, breast
cancer, brain tumors and, more recently, in other neoplasms.
Only CSC were able to grow indefinitely in vivo and invariably
reproduce the human parental tumor when injected in
immunodeficient mice. An important consequence of the
CSC model for tumor growth would be that only the targeting
of the highly malignant CSC tumor subsets would be able
to eradicate the tumor.
Methods. To tests this hypothesis we first developed a brain
tumor model based on CSC paradigm. We isolated under specific
culture conditions CSC from murine GL261 glioblastoma
(GBM) cell line, expressing high levels of stem cell
markers, growing as neurospheres, and we stereotactically
inoculated these cells into the brain of syngenic mice. This
animal model have been then used to establish a novel immunotherapeutic
protocol using dendritic cells (DC) loaded
with GBM neurospheres containing CSC (DC-NS) or total
murine glioblastoma (GBM) lysates (DC-GBM). Statistical
studies on survival and histopathological and immunophenotipical
evaluation have been performed.
Results. Glioblastoma derived neurospheres with CSC features
showed robust tumor formation in vivo and a more aggressive
infiltrating behaviour, with lower survival compared
to controls, injected with the parental GL261 glioblastoma
(GBM) cell line. MRI and histology confirmed the data.
Strikingly, dendritic cells pulsed to neurospheres (DC-NS)
protected mice against tumors from both the highly aggressive
GBM derived from CSC and the classical model. Dendritic
cells pulsed to the total lysate (DC-GBM), on the contrary,
only afforded a partial protection. Histopathological
analysis showed that DC-NS vaccination was associated with
robust tumor infiltration by CD8+ and CD4+ T lymphocytes
and signs of tumor rejection.
Conclusions. These findings suggest that DC targeting of
CSC provides a higher level of protection against GBM, even
in the presence of an highly aggressive model, a finding with
potential implications for the design of future clinical trials
based on DC vaccination.
POSTERS
Cav-1 expression is correlated with
microvessel density in human meningiomas
V. Barresi, S. Cerasoli * , G. Barresi, G. Tuccari
Dipartimento di Patologia Umana, Università di Messina,
Italy; * U.O. di Anatomia Patologica, Ospedale “M. Bufalini”,
Cesena, Italy
Introduction. Caveolin-1 (Cav-1) is a 22 KDa protein, mainly
expressed in the endothelium, smooth muscle cells, in
adipocytes and in fibroblasts. It exerts an essential but dual
role in the regulation of cell proliferation and functions as either
a pro-tumorigenic or a tumour suppressor factor in human
malignancies. Recently, Cav-1 immuno-expression in
neoplastic cells has been significantly correlated with tumour
microvessels density (MVD) in renal cell carcinoma and in
mucoepidermoid carcinoma of the salivary glands. Since we
previously demonstrated Cav-1 potential pro-tumorigenic
and negative prognostic role in human meningiomas, the aim
of the present study was to analyze Cav-1 expression in a series
of meningiomas and to correlate it with MVD measured
by the specific marker for neo-angiogenesis CD105.
Methods. 62 cases of meningiomas, classified according to
WHO 2000, were submitted to the immunohistochemical
analysis for CD105 and for Cav-1. CD105 stained vessels
were counted (400X) in the three most vascularized areas and
the mean value of three counts was recorded as the MVD of
the section. For each case, a Cav-1 ID score was also generated
by multiplying the value of the area of staining positivity
(ASP: 0 = < 10%, 1 = 11-25%, 2 = 26-50%, 3 = 51-75%,
4 = > 75%) and that of staining intensity (SI: weak = 1, moderate
= 2 and strong = 3). Chi-squared and Mann-Whitney
tests were used to assess correlations between clinico-pathological
parameters and Cav-1 ID scores or MVD counts. The
correlation between MVD and Cav-1 ID scores was tested by
using Mann-Whitney and Spermann correlation tests. Kaplan
Meier method was applied to evaluate the prognostic significance
of Cav-1 expression, MVD and other clinico-pathological
parameters on overall and recurrence-free survival.
Results. A significantly higher MVD was encountered in
cases displaying a higher Cav-1 ID score (p = 0.0001). Furthermore,
a significant positive correlation emerged between
Cav-1 ID scores and MVD counts (r = 0.390; p = 0.0023).
Higher MVD counts and higher Cav-1 ID scores were significantly
associated with a higher histological grade and Ki-
67 LI and with a shorter overall and recurrence-free survival
to meningiomas.
Conclusions. The correlation between a higher Cav-1 expression
in the neoplastic cells and tumour MVD may indicate
the role of the former as a regulator of neo-angiogenesis
in meningiomas. This might be the mechanism underlying
Cav-1 behaviour as a negative prognostic factor in meningiomas.