Extended Data Fig. 7: Increased angiogenesis elevates local leptin levels and promotes Lepr-mediated tumour progression.
From: Ras drives malignancy through stem cell crosstalk with the microenvironment
a, Fluorescently labelled leptin placed in the circulation can elevate local tissue levels of leptin in the skin and skin tumours. ELISA-like assays show that by delivery of 680RD labelled recombinant leptin through osmotic pump for 1W, fluorescence can be detected in skin and tumour tissue lysatesin a dose-depend manner. (n = 4 for each condition; Left: p = 0.0055; Right: p = 0.0199). b, Tumour growth and angiogenesis are enhanced by systemic recombinant mouse mVEGFA, delivered to the circulation by an osmotic pump distant from PDV SCC tumour sites, which are monitored for about 5W. CD31+ tumour vasculature is evaluated by flow cytometry (Left: n = 8 tumour per condition, p = 0.0004 for the end time point; Right: n = 4 per condition, p = 0.0461, paired due to the nature of angiogeneiss and relative location of pump). Vehicle control is PBS lacking mVEGFA. c, Osmotic pump delivery of recombinant protein to elevate circulating leptin levels does not appreciably induce angiogenesis in normal skin. Leptin was administered at two different doses and PBS was used as a control (n = 5 for each condition, p(PBS-Lep0.5) = 0.1133, p(Lep0.5-Lep2) = 0.0865, p(PBS-Lep2) = 0.0029). When taken with Fig. 4g, this finding indicates that elevated levels of plasma leptin on its own is sufficient to enhance tumour growth, independent of possible secondary consequences arising from enhanced angiogenesis that might otherwise bring other hormones or growth factors to the surrounding tumour tissue. d, Immunofluorescence of tissue sections for Lepr reporter and CD31. EGFP labels the CSCs; CD31 labels the vasculature. Quantifications are based on the average distance from the CD31+ vasculature to tumour basal cells with or without reporter signalling. (n = 8 regions per condition, p = 0.0049). All statistics were using unpaired (unless noted) two-tailed Student’s t-test: NS, p ≥ 0.05); *, p ≤ 0.05); **, p ≤ 0.01; ***, p ≤ 0.001; ****, p ≤ 0.0001. Data are presented as mean ± s.e.m. Scale bars, 50 µm. The diagram in b was created using BioRender.
