We inoculated NR-S1M metastatic cells subcutaneously into the backs of C3H/HeN mice. Concurrently, 1 ¦Ìg of recombinant mouse CRP or phosphate-buffered saline was injected subcutaneously every 3 days for 5 weeks, after which the mice were killed for evaluation. We evaluated lymph node metastasis and lymphangiogenesis in the implanted tumor by using immunohistochemical analysis with anti-pancytokeratin and antilymphatic vessel endothelial hyaluronan receptor-1 antibodies.
There was no substantial difference in tumor size between the 2 groups but the lymph nodes were smaller in the CRP group than the control group (P < .044). Immunohistochemical analysis confirmed inguinal lymph node metastasis in 70 % (14/20) of control mice, but in only 30 % (3/10) of mice in the CRP group. Moreover, the metastatic area within lymph nodes was less in the CRP group (P < .042) and tumoral lymphangiogenesis was decreased in the CRP group (P < .037).
CRP appears to inhibit tumoral lymphangiogenesis and lymph node metastasis in mice. These findings suggest that by inhibiting lymph node metastasis, CPR may have therapeutic potential for use against cancer.