Phenotypic alterations in Caki-1 Cells as a consequence of TIMP-1 over-expression

Maintenance of the extracellular matrix (ECM) is important for tissue integ rity and cellular physiology. Normal ECM turnover is regulated by a balance between matrix metalloproteinases and their inhibitors, the tissue inhibit ors of metalloproteinases (TIMPs), In metastasis, this balance favours incr eased ECM degradation. The objective of this study was to determine the eff ects of TIMP-1 overexpression on the metastatic process. To this end, we st ably transfected a renal carcinoma cell line, Caki-1, with TIMP-1, using a pRc/CMV expression plasmid and LIPOFECTAMINE (TM) transfection reagent. The resultant clones displayed increased adhesion on the ECM substratum, inclu ding collagen type IV and laminin, and altered invasive capacity through fi bronectin and Matrigel((R)), dependent upon the level of TIMP-1 expression. These changes were not due to altered integrin expression, as assessed by flow cytometry. As well as protease inhibitory activity, TIMPs can influenc e cell proliferation and cell survival. The TIMP-1 clones displayed no chan ges in proliferation under normal growth conditions, compared with Caki-1 c ells. However, under reduced serum conditions, the TIMP-1 clones had a grea ter percentage of cells in both S (P < 0.05) and G(2)/M (P < 0.005) phases and less cells in G(0)/G(1) (P < 0.001) of the cell cycle than Caki-1 cells . The results confirm a dual role for TIMP-1 in invasion and metastasis, an d provide further clues behind the molecular mechanisms in these processes. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.