Figure 4: TNF-α in mouse tumour lymphangiogenesis and metastasis.

(a) Confocal image of vector or TNF-α-overexpressing LLC tumours. Overexpression of TNF-α in LLC tumours promoted peritumoral and intratumoral lymphangiogenesis (red LYVE-1 signals). Dashed line marks tumour borders, and LLC tumour cells expressed EGFP (green). ITL, intratumoral lymphatics; PTL, peritumoral lymphatics; VT, vector transfected. Scale bar, 100 μm. Quantification of peritumoral and intratumoral LYVE-1⁺ lymphatics in TNF-α-overexpressing and vector-transfected LLC tumours (eight randomized fields per group). (b) Left: representative LNs of TNF-α- and vector-expressing LLC tumour-bearing mice. Scale bar, 5 mm. Right: a representative bioluminescence picture of mice that showed luciferase⁺ TNF-α- and vector-expressing LLC tumour-bearing mice. Arrowhead indicates the metastatic LN. (c) Left: hematoxylin and eosin stain (H&E) and fluorescence images of LNs. TNF-α-expressing LLC metastases were detected in LNs. Dashed line marks the rim of a metastatic tumour in LN. T, tumour. Scale bar, 100 μm (upper panels); 100 μm (lower panels). Quantification of LN volume and weight in vector and TNF-α tumour-bearing mice (n=10 mice per group). **P<0.01; ***P<0.001. All error bars represent s.e.m. All P values were analysed according to Student’s t-test.