Inhibition of tumor growth and metastasis by angiogenesis inhibitor TNP-470 on breast cancer cell lines in vitro and in vivo

Antitumor and antimetastatic activity of the angiogenesis inhibitor O-(chloroacetyl-carbamoyl) fumagillol (TNP-470), a semisynthetic analogue of fumagillin, was evaluated in breast cancer cell lines. In an in vitro MTT assay, after 72 hrs continuous exposure to TNP-470, growth inhibition was observed in all seven cell lines of murine (JYG-A, JYG-B, DD-762, and BALB/c-MC) or human (KPL-1, MDA-ME-231, and MKL-F) ori gin, in which the 50% inhibitory concentrations (IC50) at 72 hrs treatment were 4.6, 4.4, 4.6, 10.1, 35.0, 25.3, and 33.4 mu g/ml, respectively. In an in vivo assay using JYG-A, JYG-B, KPL-1, and MDA-MB-231 cells by orthotopic (right thoracic mammary fat pad) transplantation in female nude mice, TNP-470 at 30 or 50 mg/kg body weight was injected s.c. every other day from the day of tumor cell inoculation until the end of the experiment. The inhibitory effect on primary tumor growth was obtained in all four cell lines in a dose-dependent manner. In the 50 mg/kg TNP-470-treated group, the reductions in tumor weight of the JYG-A, JYG-B, KPL-1, and MDA-MB-231 cells with respect to the controls were 50%, 30%, 4%, and 49%, respectively. Metastasis was seen in the JYG-A, JYG-B, and KPL-1 cells. The numbers of mice bearing pulmonary metastases of JYG-A and JYG-B cells and regional axillary lymph node metastases of KPL-1. cells were reduced, and TNP-470 at the 50 mg/kg dose to KPL-1 cells significantly reduced lymph node metastases compared with the control. Although the weight gain was retarded in the TNP-470-treated mice, weight loss was not seen. TNP-470 was highly effective in the treatment of breast cancer cells. These results suggest that the clinical use of TNP-470 may be a promising treatment for breast cancer patients.