TIMP-2 OVER-EXPRESSION REDUCES INVASION AND ANGIOGENESIS AND PROTECTSB16F10 MELANOMA-CELLS FROM APOPTOSIS

The matrix metalloproteinase (MMP) inhibitor TIMP-2 has a high specifi city for gelatinase A/MMP-2. An imbalance between gelatinase A and TIM P-2 in favor of enzymatic activity is linked to the degradation of the extracellular matrix (ECM) associated with several physiologic and pa thologic events, including angiogenesis, invasion and metastasis. Sinc e TIMPs are secreted molecules, they have the potential to be used for gene therapy of certain tumors, We transfected B16F10 murine melanoma cells, a highly invasive and metastatic cell line, with an expression vector harboring a cDNA encoding for human TIMP-2. The clones obtaine d were isolated and examined for TIMP-2 over-expression and changes in tumor cell phenotype. The amount of recombinant TIMP-2 produced corre lated with a reduction in invasion, In an in vivo angiogenesis assay, TIMP-2-transfected clones showed reduced levels of blood vessel format ion, and in vitro conditioned media from TIMP-2 transfectants showed d iminished induction of endothelial cell migration and invasion. TIMP-2 over-expression limited tumor growth in vivo and neoangiogenesis when cells were injected subcutaneously in mice in the presence of Matrige l. However, TIMP-2 over-expressing clones were found to be more resist ant to apoptosis than parental and control melanoma cells, while necro sis was increased. Our data confirm the role of TIMP-2 in the down-reg ulation of metastasis and angiogenesis but indicate a possible involve ment in tumor cell survival. (C) 1998 Wiley-Liss, Inc.