Marie-Catherine Vozenin-Brotons

Fibrogenic signals in patients with radiation enteritis are associated with increased connective tissue growth factor expression

PURPOSEnTo investigate the expression of a new fibrogenic cytokine the connective tissue growth factor (CTGF) in intestinal radiation fibrosis and to characterize the mesenchymal cell subtypes involved in CTGF synthesis and collagen deposition.nnnMETHODS AND MATERIALSnSixteen patients with radiation enteritis that occurred after radiotherapy for pelvic malignancies and 6 with histologically normal bowel entered the study. Immunohistochemistry, Western blot analysis, and real-time reverse transcriptase-polymerase chain reaction were performed to study CTGF expression, along with other known markers of radiation fibrosis: the pro-fibrogenic cytokine transforming growth factor (TGF)-beta1 and phenotypic markers of the fibroblast differentiation the alpha-sm actin (A), vimentin (V), and desmin (D). Finally, the collagen accumulation was measured by Sirius red staining and colorimetric assay.nnnRESULTSnRadiation enteritis was characterized by increased collagen content within the intestinal wall. CTGF immunoreactivity, protein, and mRNA level were increased in radiation enteritis compared with the healthy bowel. On the contrary, no increase of the TGF-beta1 mRNA level was observed in radiation enteritis compared with healthy bowel, and the level of TGF-beta protein was slightly increased in radiation enteritis. A co-localization of CTGF immunoreactivity and collagen deposition was found in the extracellular matrix and subtypes of activated mesenchymal cells with a fibroblast phenotype (V(+)/D(-)/A(-)) and myofibroblast phenotype (V(+)/D(-/+)/A(+)).nnnCONCLUSIONnThe increased level of CTGF protein and mRNA associated with the accumulation of fibroblasts/myofibroblasts and collagen deposition were parts of the fibrogenic signals involved in the persistence of late intestinal radiation fibrosis.

Novel Anti-Metastatic Action of Cidofovir Mediated by Inhibition of E6/E7, CXCR4 and Rho/ROCK Signaling in HPV+ Tumor Cells

Cervical cancer is frequently associated with HPV infection. The expression of E6 and E7 HPV oncoproteins is a key factor in its carcinogenicity and might also influence its virulence, including metastatic conversion. The cellular mechanisms involved in metastatic spread remain elusive, but pro-adhesive receptors and their ligands, such as SDF-1α and CXCR4 are implicated. In the present study, we assessed the possible relationship between SDF-1α/CXCR4 signaling, E6/E7 status and the metastatic process. We found that SDF-1α stimulated the invasion of E6/E7-positive cancer cell lines (HeLa and TC-1) in Matrigel though CXCR4 and subsequent Rho/ROCK activation. In pulmonary metastatic foci generated by TC-1 cells IV injection a high proportion of cells expressed membrane-associated CXCR4. In both cases models (in vitro and in vivo) cell adhesion and invasion was abrogated by CXCR4 immunological blockade supporting a contribution of SDF-1α/CXCR4 to the metastatic process. E6 and E7 silencing using stable knock-down and the approved anti-viral agent, Cidofovir decreased CXCR4 gene expression as well as both, constitutive and SDF-1α-induced cell invasion. In addition, Cidofovir inhibited lung metastasis (both adhesion and invasion) supporting contribution of E6 and E7 oncoproteins to the metastatic process. Finally, potential signals activated downstream SDF-1α/CXCR4 and involved in lung homing of E6/E7-expressing tumor cells were investigated. The contribution of the Rho/ROCK pathway was suggested by the inhibitory effect triggered by Cidofovir and further confirmed using Y-27632 (a small molecule ROCK inhibitor). These data suggest a novel and highly translatable therapeutic approach to cervix cancer, by inhibition of adhesion and invasion of circulating HPV-positive tumor cells, using Cidofovir and/or ROCK inhibition.

Expression and activation of MMP -2, -3, -9, -14 are induced in rat colon after abdominal X-irradiation

Objective. Colonic response to single-dose irradiation is characterized by epithelial denudation followed by restitution. Extracellular matrix (ECM) remodeling is involved in both of these phases. The aim of this study was to characterize the contribution of matrix metalloproteinases (MMPs) and of their stimulatory and inhibitory pathways in radiation-induced ECM remodeling in colonic tissue. Material and methods. Rats were irradiated with single-dose 10 Gy X-rays to the abdomen. Activity, localization, and mRNA levels of MMPs and molecules involved in their activation and inhibition (plasmin/plasminogen; TIMPs), of inflammatory mediators (IL-1β, TNF-α) in the distal colon, 1, 3, and 7 days after irradiation were analyzed using a combination of approaches including zymography, immunohistochemistry, and real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Results. The main finding of this study is that radiation-induced alteration of the mucosal structure is concomitant with local increased expression and activation of MMP subtypes involved in basement membrane degradation (MMP-2, -3, and -9). We investigated MMP-2 activation pathways and found an early increase in mRNA levels of soluble inflammatory mediators (TNF-α and IL-1β). Furthermore, transcription and activity of MMP-2 activating molecules, such as MMP-14, and molecules involved in the plasminogen/plasmin system were found to increase during the denudation phase. Interestingly, induction of MMP inhibitors TIMP-1 and PAI-1 was observed during the restitution phase. MMP inhibitors may be able to stop acute wound healing response by inhibiting ECM degradation. Conclusions. This study brings new insights into ECM remodeling in the colon after exposure to ionizing radiation and highlights the role of MMP subtypes specialized in basement membrane degradation.