Characterization of the tumor micro-environment after administration of glucocorticoids to understand their radiosensitization effect
; ; et al
Poster (2004, November 26)Detailed reference viewed: 7 (0 ULg)
Intrinsic and irradiation-induced tumor selectivity of liposome-based gene therapy targeting Akt activation.
Martinive, Philippe ; ; et al
Poster (2004, September)Detailed reference viewed: 5 (1 ULg)
caveolin-1 expression is critical for VEGF-induced inschemic hindlimb collateralization and NO-mediated angiogenisis.
Martinive, Philippe ; ; et al
in Circulation Research (2004), (95 (2)), 154-61
Nitric oxide (NO) is a powerful angiogenic mediator acting downstream of vascular endothelial growth factor (VEGF). Both the endothelial NO synthase (eNOS) and the VEGFR-2 receptor colocalize in caveolae ... [more ▼]
Nitric oxide (NO) is a powerful angiogenic mediator acting downstream of vascular endothelial growth factor (VEGF). Both the endothelial NO synthase (eNOS) and the VEGFR-2 receptor colocalize in caveolae. Because the structural protein of these signaling platforms, caveolin, also represses eNOS activity, changes in its abundance are likely to influence the angiogenic process in various ways. In this study, we used mice deficient for the caveolin-1 gene (Cav-/-) to examine the impact of caveolae suppression in a model of adaptive angiogenesis obtained after femoral artery resection. Evaluation of the ischemic tissue perfusion and histochemical analyses revealed that contrary to Cav+/+ mice, Cav-/- mice failed to recover a functional vasculature and actually lost part of the ligated limbs, thereby recapitulating the effects of the NOS inhibitor L-NAME administered to operated Cav+/+ mice. We also isolated endothelial cells (ECs) from Cav-/- aorta and showed that on VEGF stimulation, NO production and endothelial tube formation were dramatically abrogated when compared with Cav+/+ ECs. The Ser1177 eNOS phosphorylation and Thr495 dephosphorylation but also the ERK phosphorylation were similarly altered in VEGF-treated Cav-/- ECs. Interestingly, caveolin transfection in Cav-/- ECs redirected the VEGFR-2 in caveolar membranes and restored the VEGF-induced ERK and eNOS activation. However, when high levels of recombinant caveolin were reached, VEGF exposure failed to activate ERK and eNOS. These results emphasize the critical role of caveolae in ensuring the coupling between VEGFR-2 stimulation and downstream mediators of angiogenesis. This study also provides new insights to understand the paradoxical roles of caveolin (eg, repressing basal enzyme activity but facilitating activation on agonist stimulation) in cardiovascular pathophysiology. [less ▲]Detailed reference viewed: 24 (5 ULg)
Endothelin-1 is a critical mediator of myogenic tone in tumor arterioles: implications for cancer treatment.
; ; MARTINIVE, Philippe et al
in Cancer Research (2004), 1(64), 3209-14
Although derived from the host tissue, the tumor vasculature is under the influence of the tumor microenvironment and needs to adapt to the resistance to blood flow inherent to the dynamics of tumor ... [more ▼]
Although derived from the host tissue, the tumor vasculature is under the influence of the tumor microenvironment and needs to adapt to the resistance to blood flow inherent to the dynamics of tumor growth. Such vascular remodeling can offer selective targets to pharmacologically modulate tumor perfusion and thereby improve the efficacy of conventional anticancer treatments. Radiotherapy and chemotherapy can, indeed, take advantage of a better tumor oxygenation and drug delivery, respectively, both partly dependent on the tumor blood supply. Here, we showed that isolated tumor arterioles mounted in a pressure myograph have the ability, contrary to size-matched healthy arterioles, to contract in response to a transluminal pressure increase. This myogenic tone was exquisitely dependent on the endothelin-1 pathway because it was completely abolished by the selective endothelin receptor A (ETA) antagonist BQ123. This selectivity was additionally supported by the large increase in endothelin-1 abundance in tumors and the higher density of the ETA receptors in tumor vessels. We also documented by using laser Doppler microprobes and imaging that administration of the ETA antagonist led to a significant increase in tumor blood flow, whereas the perfusion in control healthy tissue was not altered. Finally, we provided evidence that acute administration of the ETA antagonist could significantly stimulate tumor oxygenation, as determined by electron paramagnetic resonance oximetry, and increase the efficacy of low-dose, clinically relevant fractionated radiotherapy. Thus, blocking the tumor-selective increase in the vascular endothelin-1/ETA pathway led us to unravel an important reserve of vasorelaxation that can be exploited to selectively increase tumor response to radiotherapy. [less ▲]Detailed reference viewed: 47 (8 ULg)
Targeting the vascular tone of microarterioles with an endothelin-1 (ET-1) antagonist selectively modulates tumor blood flow and promotes response to treatment
Poster (2004, January)Detailed reference viewed: 21 (5 ULg)
Reversal of temporal and spatial heterogeneities in tumor perfusion identifies the tumor vascular tone as a tunable parameter to improve drug delivery
Poster (2003)Detailed reference viewed: 10 (3 ULg)