Tumour growth inhibition and anti-metastatic activity of a mutated furin-resistant Semaphorin 3E isoform.
Bottom Line: Here, we show that a mutated, uncleavable variant of Sema3E (Uncl-Sema3E) binds to PlexinD1 like p61-Sema3E, but does not promote the association of PlexinD1 with ErbB2 nor activates the ensuing signalling cascade leading to metastatic spreading.It activates a PlexinD1-mediated signalling cascade in endothelial cells that leads to the inhibition of adhesion to extracellular matrix, directional migration and cell survival.In summary, we conclude that Uncl-Sema3E is a novel inhibitor of tumour angiogenesis and growth that concomitantly hampers metastatic spreading.
Affiliation: Institute for Cancer Research and Treatment (IRCC), University of Torino Medical School, Candiolo, Italy.Show MeSH
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Mentions: In order to compare the effect of Uncl-Sema3E with that of a validated anti-angiogenic molecule, we exploited two metastatic tumour models characterized by different responsiveness to VEGF-targeted anti-angiogenic therapy. In particular, 4T1 mammary carcinoma cells are highly responsive to anti-VEGF(R) treatments, which effectively leads to tumour shrinkage (Fischer et al, 2007); in contrast, it has been shown previously that tumours formed by Lewis Lung Carcinoma Cells (LLc) are refractory to this therapeutic approach (Shojaei et al, 2007). We therefore delivered complementary DNA (cDNA) constructs encoding either a soluble VEGF trap consisting of the extracellular portion of VEGFR2 (sFlk1), Uncl-Sema3E or mock control into immunodeficient mice. These mice were then randomized into two groups for each construct and transplanted with either 4T1 or LLc cells the day after hydroporation. The plasma levels of either molecule were comparable between mice carrying different models, as assessed by ELISA (Table 1), and the growth of 4T1 tumours was remarkably inhibited in the presence of both anti-angiogenic factors (Fig 9A and B). However, while LLc tumours were insensitive to anti-VEGF therapy (as expected), their growth was dramatically impaired by Uncl-Sema3E (Fig 9D and E), consistent with the direct inhibitory activity of this molecule in endothelial cells. Notably, vessel density was remarkably reduced in LLc tumours treated with Uncl-Sema3E, while it was comparable to controls in the presence of sFlk1 (Fig 9G). Upon analyzing the metastatic dissemination at the end of the experiment, we found that tumour shrinkage elicited by sFlk1 was accompanied by an increased number of lung metastasis (Fig 9C and F). In contrast, the tumour suppressing activity of Uncl-Sema3E was coupled with a reduction of metastatic dissemination compared to controls in both models (Fig 9C and F), indicating that it is a valuable therapeutic tool to treat tumours independently from their responsiveness to anti-VEGF drugs.
Affiliation: Institute for Cancer Research and Treatment (IRCC), University of Torino Medical School, Candiolo, Italy.