The tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) has been recognized as a multifunctional protein. The role of TIMPs in cancer remains the subject of conflicting reports with an antitumor activity or a tumor growth stimulation activity by several mechanisms. The aim of our study is to investigate the effect of ectopic TIMP-1 overexpression on the primary transplanted tumor growth. We employed transgenic mice overexpressing the human TIMP-1 (hTIMP-1) in the liver under control of the albumin promoter/enhancer (TIMP-Tg-mice) and producing high serum levels of TIMP-1. We used the transplantable Ehrlich tumor cells in the current study. The allograft study revealed that the tumor growth in the TIMP-Tg-mice was more significantly inhibited than control (Cont) mice by associated suppression of neovascularization in the tumor. The in vitro studies showed that the recombinant TIMP-1 (rTIMP-1) did not affect the proliferation of the endothelial cells (ECs) and tumor cells, suggesting that the tumor suppressive effect of TIMP-1 was not due to cytotoxicity. TIMP-1 significantly inhibited EC tubular formation in vitro. Furthermore, TIMP-1 treatment did not affect the levels of matrix metalloproteinase (MMP)-2 and MMP-9 mRNA in the Ehrlich tumor cells in vitro, although these expressions in the tumor were markedly suppressed in the TIMP-Tg-mice, compared to the Cont-mice at the end of the experiment. These results suggested that the ectopically overexpressed TIMP-1 inhibited the tumor growth by angiogenesis suppression.
Copyright 2003 Wiley-Liss, Inc.