Specific expression of matrix metalloproteinases 1, 3, 9 and 13 associatedwith invasiveness of breast cancer cells in vitro

Several matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIM Ps) were studied in highly invasive (MDA-MB-231) and slightly invasive (MCF -7, T47D, BT-20) breast cancer cell lines. Investigations were carried out at the protein level and/or at the mRNA level, either in cells cultured as monolayers on plastic, or in cells seeded on a thin layer of Matrigel basem ent membrane matrix. Analysis of MMP expression by RT-PCR showed expression of MMP-1, MMP-3, and MMP-13 in highly invasive MDA-MB-231 cells, but not i n slightly invasive cell lines. The extracellular secretion of MMP-1 and MM P-3 by MDA-MB 231 cells could be also shown by ELISA. TIMP-1 and TIMP-2 mRN As were found in all cell lines, however, the extracellular secretion of bo th TIMPs was much higher in MDA-MB-231 cells than in the other cell lines. When the cells were cultured on Matrigel matrix, MMP-9 expression was induc ed in MDA-MB-231 cells only, as assessed by RT-PCR and zymography experimen ts. The invasive potential of MDA-MB-231 cells evaluated in vitro through M atrigel was significantly inhibited by the MMP inhibitor BB-2516, by 25% an d 50% at the concentrations of 2 x 10(-6) M and 10(-5) M, respectively. In conclusion, our data show that highly invasive MDA-MB-231 cells but not sli ghtly invasive T47D, MCF-7 and BT-20 cells express MMP-1, MMP-3, MMP-9 and MMP-13. MMP-9 which is specifically up-regulated by cell contact to Matrige l, may play a key role in the invasiveness of MDA-MB-231 cells through base ment membranes.