Multiple signaling pathways involved in activation of matrix metalloproteinase-9 (MMP-9) by heregulin-β1 in human breast cancer cells

Abstract

Matrix metalloproteinase-9 (MMP-9) plays important roles in tumor invasion and angiogenesis. Secretion of MMP-9 has been reported in various cancer types including lung cancer, colon cancer, and breast cancer. In our investigation of MMP-9 regulation by growth factors, MMP-9 was activated by heregulin-b1 as shown by zymography in both SKBr3 and MCF-7 breast cancer cell lines. Increase in MMP-9 activity was due to increased MMP-9 protein and mRNA levels, which mainly results from transcriptional upregulation of MMP-9 by heregulinb1. Heregulin-b1 activates multiple signaling pathways in breast cancer cells, including Erk, p38 kinase, PKC, and PI3-K pathways. We examined the pathways involved in heregulin-b1-mediated MMP-9 activation using chemical inhibitors that speci®cally inhibit each of these heregulinb1-activated pathways. The PKC inhibitor RO318220 and p38 kinase inhibitor SB203580 completely blocked heregulin-b1-mediated activation of MMP-9. MEK-1 inhibitor PD098059 partially blocked MMP-9 activation, whereas PI3-K inhibitor wortmannin had no e ect on heregulin-b1-mediated MMP-9 activation. Therefore, at least three signaling pathways are involved in the activation of MMP-9 by heregulin-b1. Since MMP-9 is tightly associated with invasion/metastasis and angiogenesis, our studies suggest that blocking heregulin-b1-mediated activation of MMP-9 by inhibiting the related signaling pathways may provide new strategies for inhibition of cancer metastasis and angiogenesis. Oncogene (2001) 20, 8066 ± 8074.

Soluble Urokinase-type Plasminogen Activator Receptor Inhibits Cancer Cell Growth and Invasion by Direct Urokinase-independent Effects on Cell Signaling

“…These changes in cell physiology have been previously linked to the basal level of ERK activation (65,66). The extent of cell growth inhibition (nearly 100%) was unanticipated.…”

Transcriptional Repression of Protein Kinase Cα via Sp1 by Wild Type p53 Is Involved in Inhibition of Multidrug Resistance 1 P-Glycoprotein Phosphorylation

“…Reporter Gene Assays-Reporter gene assays were performed as described previously (15). Briefly, SKLMS-1 cells were seeded at a density of 2 ϫ 10 5 cells/well in 6-well plates and incubated in complete medium overnight at 37°C.…”

“…Cells were subsequently treated with Ad-p53 or Ad-LacZ and further incubated for 48 h. Using FuGENE 6, cells were then cotransfected with 1 g of pGL3-basic containing the various PKC␣ deletion constructs and 0.5 g of the internal control pSV40-␤-galactosidase. Twenty-four hours later, SKLMS-1 were harvested, and luciferase activity was determined and normalized to ␤-galactosidase activity (15).…”

“…Mutation of the tumor suppressor gene p53 is commonly found in a wide variety of human tumors and is one of the most common genetic alterations in soft tissue sarcoma (STS), occurring in 30 -60% of these tumors (15). Interestingly, p53 missense mutations occur more frequently than non-sense mutations (16).…”

Blockage of heregulin expression inhibits tumorigenicity and metastasis of breast cancer

“…MMP-9 is required for this process, because a ribozyme directed against MMP-9 abolishes the ability of the cells to metastasize (Hua and Muschel, 1996). Moreover, it has been shown recently that MMP-9 expression is activated by HRG (Yao et al, 2001), and that the erbB-2-mediated Ras-dependent MAPK pathway is involved in the upregulation of MMPs (Tsang and Crowe, 2001). We have previously demonstrated that HRG promotes tumorigenicity in part via upregulation of an angiogenic factor Cyr61 (Tsai et al, 2000), and also via receptor tyrosine phosphorylation and MAPK activation (Atlas et al, 2003;Tsai et al, 2002).…”