Sublethal whole-body irradiation causes progressive premature frailty in mice.

There is an unmet need to develop and validate therapies that can treat or at least prevent premature therapy-induced frailty, multi-morbidity and mortality in long-term tumour survivors. In an approach to develop a first mouse model for therapy-induced long-term frailty, we irradiated male C57Bl/6 mice at 5-6 months of age sub-lethally with 3 × 3 Gy (whole body) and assessed subsequent frailty for up to 6 months using a Rockwood-type frailty index (FI). Frailty scorers were trained to obtain excellent inter- and intra-observer reproducibility. Irradiated mice developed progressive frailty approximately twice as fast as controls. This was premature frailty; it was phenotypically identical to that in non-irradiated mice at higher age. As expected, frailty was associated with decreased cognition and predicted mortality. In irradiated mice, frailty and neuromuscular performance, measured by Rotarod and Hanging Wire tests, were not associated with each other, probably because of long-term decreased body weights after irradiation. We conclude that progressive frailty following sub-lethal irradiation comprises a sensitive and easy to use test bed for interventions to stop premature ageing in long-term tumour survivors.

Autocrine vascular endothelial growth factor signalling in breast cancer. Evidence from cell lines and primary breast cancer cultures in vitro.

Inhibition of angiogenesis has become a major target in experimental cancer therapies. Vascular endothelial growth factor (VEGF) and its receptors are essential for breast cancer progression and relevant targets in experimental anti-angiogenesis. VEGF, produced by carcinoma cells, acts in a paracrine fashion on endothelial cells and displays autocrine activity on carcinoma cells. Breast cancer cells express VEGF-A, VEGF-B, VEGF-C and their receptors VEGFR-1 (Flt-1), VEGFR-2 (Flk-1/KDR) and neuropilin (NP-1/NP-2). VEGF-A triggers cellular signalling, an invasive phenotype of certain breast cancer cell lines and influences cell survival. However, such an autocrine VEGF/VEGFR signalling loop remains to be established. We demonstrate production of VEGF-A in cell lines MDA-MB-468, T47d, MCF-7, HBL-100 and in a primary breast cancer culture. Moreover, these cells showed baseline VEGFR-2 tyrosine-phosphorylation that could be enhanced by VEGF-A stimulation. In addition, VEGF-A leads to increased phosphorylation of ERK1/2 and Akt indicating that VEGF-A stimulation plays a crucial role in the regulation of cell growth, apoptosis, survival and differentiation. Moreover, we have established a novel breast cancer cell culture MW1 that expresses high levels of VEGF-A. We demonstrate that VEGFR-2 on the surface of breast cancer cells is functional and is capable of being stimulated by external VEGF-A. VEGF-A production by and VEGFR-2 activation on the surface of breast cancer cells indicates the presence of a distinct autocrine signalling loop that enables breast cancer cells to promote their own growth and survival by phosphorylation and activation of VEGFR-2. Moreover, this autocrine loop represents an attractive therapeutic target.

Angiogenesis during primate placentation in health and disease.

Normal embryonic development is dependent upon a sufficient oxygen, nutrient and waste exchange through the placenta. In primates including humans, this exchange is attained by successful haemochorial placentation which requires the transformation of maternal intramyometrial spiral arterioles by trophoblast invasion to gain uteroplacental circulation, and establishment and maintenance of a competent fetoplacental vasculature. Thus, trophoblast and endothelial cell differentiation, proliferation and invasion occurring during placentation have to be tightly regulated. This review focuses on the diverse developmental steps during haemochorial placentation in humans and other primates and the possible involvement of angiogenic growth factors (vascular endothelial growth factor (VEGF) and angiopoietins (Ang)) in these processes, highlighting the importance of specific actions of angiogenic ligand-receptor pairs. It is hypothesized that VEGF/VEGF-R1 and Ang-1/Tie receptor 2 (Tie-2) may regulate trophoblast differentiation and invasion; VEGF/VEGF-R2 and Ang-1/Tie-2 may promote fetoplacental vascular development and stabilization; and Ang-2/Tie-2 may be involved in maternal vascular remodelling. The importance of a tight regulation of angiogenic factors and their endogenous antagonists for normal development of the placenta is demonstrated by failure of this system, resulting in abnormal placenta vascularization and trophoblast invasion associated with intrauterine growth retardation or pre-eclampsia.