Page 16 - AnnualReportGIGA2012

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14
J Proteome Res. 2012 Oct 5;11(10):5011-21.
Sparc-like protein 1 is a new marker of human
glioma progression.
Turtoi A, Musmeci D, Naccarato AG, Scatena C, Ortenzi V, Kiss R, Murtas D, Patsos G,
Mazzucchelli G, De Pauw E, Bevilacqua G, Castronovo V.
Abstract
High-grade gliomas (glioblastomas) are the most common and deadly brain tumors in adults,
currently with no satisfactory treatment available. Apart from de novo glioblastoma, it is
currently accepted that these malignancies mainly progress from lower grade glial
tumors. However, the molecular entities governing the progression of gliomas are poorly
understood. Extracellular and membrane proteins are key biomolecules found at the cell-
to-cell communication interface and hence are a promising proteome subpopulation that
could help understand the development of glioma. Accordingly, the current study aims at
identifying new protein markers of human glioma progression. For this purpose, we used glial
tumors generated orthotopically with T98G and U373 human glioma cells in nude mice. This
setup allowed also to discriminate the protein origin, namely, human (tumor) or mouse (host).
Extracellular and membrane proteins were selectively purifed using biotinylation followed
by streptavidin afnity chromatography. Isolated proteins were digested and then identi-
fed and quantifed employing 2D-nano-HPLC-MS/MS analysis. A total of 23 and 27 up-re-
gulated extracellular and membrane proteins were identifed in the T98G and U373 models,
respectively. Approximately two-thirds of these were predominantly produced by the
tumor, whereas the remaining proteins appeared to be mainly overexpressed by the host
tissue. Following extensive validation, we have focused our attention on sparc-like protein
1. This protein was further investigated using immunohistochemistry in a large collection
of human glioma samples of diferent grades. The results showed that sparc-like protein 1
expression correlates with glioma grade, suggesting the possible role for this protein in the
progression of this malignancy.
Oncogene. 2012 Aug 16;31(33):3741-53.
A dynamic in vivo model of epithelial-to-mesen-
chymal transitions in circulating tumor cells and
metastases of breast cancer.
Bonnomet A, Syne L, Brysse A, Feyereisen E, Thompson EW, Noël A, Foidart JM, Birembaut P,
Polette M, Gilles C.
Abstract
Epithelial-to-mesenchymal transition (EMT) processes endow epithelial cells with
enhanced migratory/invasive properties and are therefore likely to contribute to tumor
invasion and metastatic spread. Because of the difculty in following EMT processes in
human tumors, we have developed and characterized an animal model with transplan-
table human breast tumor cells (MDA-MB-468) uniquely showing spontaneous EMT events
to occur. Using vimentin as a marker of EMT, heterogeneity was revealed in the primary
MDA-MB-468 xenografts with vimentin-negative and vimentin-positive areas, as also
observed on clinical human invasive breast tumor specimens. Reverse transcriptase-PCR
after microdissection of these populations from the xenografts revealed EMT traits in the
vimentin-positive zones characterized by enhanced ‘mesenchymal gene’ expression (Snail,
Slug and fbroblast-specifc protein-1) and diminished expression of epithelial molecules
(E-cadherin, ZO-3 and JAM-A). Circulating tumor cells (CTCs) were detected in the blood
as soon as 8 days after s.c. injection, and lung metastases developed in all animals injected as
examined by
in vivo
imaging analyses and histology. High levels of vimentin RNA were detec-
ted in CTCs by reverse transcriptase-quantitative PCR as well as, to a lesser extent, Snail
and Slug RNA. Von Willebrand Factor/vimentin double immunostainings further showed that
tumor cells in vascular tumoral emboli all expressed vimentin. Tumoral emboli in the lungs also
expressed vimentin whereas macrometastases displayed heterogenous vimentin expression,
as seen in the primary xenografts. In conclusion, our data uniquely demonstrate in an
in vivo
context that EMT occurs in the primary tumors, and associates with an enhanced ability to
intravasate and generate CTCs. They further suggest that mesenchymal-to-epithelial pheno-
mena occur in secondary organs, facilitating the metastatic growth.