title: Cell density-dependent regulation of matrix metalloproteinase and TIMP expression in differently tumorigenic breast cancer cell lines.
abstract: Matrix metalloproteinases (MMPs) play a key role in cellular invasion and growth. Recent observations on tumor tissue samples suggest that MMP activity is altered in relation to cell density. Therefore, we examined MMP(-1,-2,-3,-8,-9,-10,-11 and -13) and TIMP-1/-2 expression of well-defined cell densities in breast carcinoma cell lines with differing in vivo tumorigenicity/invasiveness (MCF-7 < MDA-MB-468 < MDA-MB-231 < MDA-MB-435). Chemoinvasion assays were performed to link the in vitro data to the in vivo behavior. In accord with previous in vivo data, expression levels of most MMPs decreased significantly with increasing cell density and correlated well with a lower in vitro invasiveness of confluent cells. Since these data suggested that cell density regulates transcription and the promoter regions of most MMPs have AP-1 transcription factor binding consensus sequences, we tested whether functional AP-1 protein was involved in the mechanism of MMP downregulation by cell density. A role for AP-1 was confirmed by over-expression of c-Jun and c-fos in confluent MDA-MB-231 cells, showing with c-Jun increased MMP-2 (5-fold), MMP-3 (1.6-fold), and MMP-9 (160-fold) expression, as well as enhanced invasive potential, while TIMP-1 expression was down-regulated (2-fold) when compared to vector controls. Our data provide clear evidence that cell density regulates major MMPs and TIMPs which are controlled by AP-1 activity so that ultimately a major regulation pathway for the control of the invasive potential of tumor cells is presented.
authors.affiliation: Department Clinical Chemistry and Clinical Biochemistry, Hospital of Surgery, Ludwig-Maximilians-University, Nussbaumstr. 20, D-80336 München, Germany. bachmeier@clinbio.med.uni-muenchen.de
authors.forename: Beatrice E
authors.initials: BE
authors.lastname: Bachmeier
authors.forename: Adriana
authors.initials: A
authors.lastname: Albini
authors.forename: Roberta
authors.initials: R
authors.lastname: Vené
authors.forename: Roberto
authors.initials: R
authors.lastname: Benelli
authors.forename: Douglas
authors.initials: D
authors.lastname: Noonan
authors.forename: Cora
authors.initials: C
authors.lastname: Weigert
authors.forename: Christoph
authors.initials: C
authors.lastname: Weiler
authors.forename: Ralf
authors.initials: R
authors.lastname: Lichtinghagen
authors.forename: Marianne
authors.initials: M
authors.lastname: Jochum
authors.forename: Andreas G
authors.initials: AG
authors.lastname: Nerlich
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D002452:Cell Count; D045744:Cell Line, Tumor; D016895:Culture Media, Serum-Free; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020782:Matrix Metalloproteinases / Q000235:genetics*; D009361:Neoplasm Invasiveness; D016133:Polymerase Chain Reaction; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019714:Tissue Inhibitor of Metalloproteinases / Q000235:genetics*
chemical_list: D016895:Culture Media, Serum-Free; D012334:RNA, Neoplasm; D019714:Tissue Inhibitor of Metalloproteinases; D020782:Matrix Metalloproteinases