Figure 5.

Evaluation of the effect of rapamycin on intratumoral lymphangiogenesis and lymphatic metastasis using an experimental metastatic model in nude mice. 5.0 × 10.0⁶ B13LM cells were injected subcutaneously into the left inferior limb. Tumors were allowed to grow for 7 days and then rapamycin (1.5 mg/kg per day) (n = 10) or the vehicle alone (n = 11) was intraperitoneally given to the mice every day. The subcutaneous tumor volume ([major axis] × [minor axis]² × π/6) was measured every other day (a). Inhibition of the tumor growth was observed in rapamycin‐treated mice at day 20 (P = 0.009). After 3 weeks from the start of treatment, mice were killed. Lymphatic vessels in the subcutaneous tumors were evaluated using LYVE‐1 immunostains and computer‐assisted quantitative analysis. (b) Representative examples of LYVE‐1 immunostains of the subcutaneous tumors (left, control mice; right, rapamycin‐treated mice). The lymphatic vessels were less conspicuous in the tumor of rapamycin‐treated mice than that of control mice. (c) Ten hot spots having the greatest number of LYVE‐1‐positive vessels were selected in each slide and evaluated. The number (left) and the area (right) of lymphatic vessels were significantly decreased in rapamycin‐treated mice (P < 0.001 and P = 0.033, respectively).