Overexpression of MMP-9 and HIF-1α in Breast Cancer Cells under Hypoxic Conditions

Abstract

PurposeHypoxia, which is a loss of oxygen in tissues, is a common condition in solid tumors due to the tumor outgrowing existing vasculature. Under hypoxic conditions, hypoxia-inducible factor (HIF)-1α rapidly accumulates and transactivates hundreds of genes, such as matrix metalloproteinases (MMPs). MMPs contribute to invasion and metastasis of tumor cells by degrading the surrounding basement membrane and extracellular matrix barriers, which enables the easy migration and spread of cancer cells. We examined whether hypoxia increases tumor cell invasion, and whether increased invasiveness was due to HIF-1α and MMP-9 expression.MethodsTranswell invasion assays were performed to demonstrate whether hypoxia enhance tumor invasion by use of MDA-MB-231 breast cancer cells. An immunofluorescence assay was used to demonstrate expression of HIF-1α and MMP-9 under hypoxic conditions. Luciferase and ChiP assays were performed to demonstrate that MMP-9 promoter activity was regulated by HIF-1α.ResultsHIF-1α was stabilized under hypoxic conditions and stimulated MMP-9 expression, which affected the tumor invasiveness of breast cancer cells. HIF-1α transactivated the MMP-9 promoter by forming a transcriptional unit with p300, thus increasing expression of MMP-9 transcripts. Zymography indicated that MMP-9 had more gelatinase activity under hypoxic conditions than normoxic conditions. Furthermore, the small GTPase Ras was also activated in response to hypoxia, which then aids stabilization of HIF-1α, and in turn upregulates MMP-9 expression. We also demonstrate that MMP-9 is upregulated concurrently with HIF-1α in tumor tissues from patients with breast cancer.ConclusionThese results suggest that HIF-1α promotes cell invasion through a MMP-9-dependent mechanism and that future antitumor agents could be used to target HIF-1α and MMP-9.

Down-regulation of MTA1 protein leads to the inhibition of migration, invasion, and angiogenesis of non-small-cell lung cancer cell line

“…After MTA1 protein was downregulated by MTA1-siRNA, the migration and invasion potentials of 95D cells significantly decreased, which is consistent with the previous report [32], indicating that MTA1 protein mediated regulation of the aggressive phenotypes of 95D cells in vitro, while the regulating pathways is not clear. It is well known that MMP-9 is critically involved in the processes of cancer cell migration and invasion [33,34]. The regulatory role of MTA1 protein on MMP-9 has been investigated in different malignant tumors; however, the results were controversial [35][36][37].…”

Hypoxia and the extracellular matrix: drivers of tumour metastasis

“…Hypoxia is associated with an increase in the expression and the activity of type IV collagen-degrading enzymes (MMP2 and MMP9) in vitro 94–96 . MMP2 and MMP9 are upregulated by hypoxia in breast and colon cancer cells via a HIF1-dependent mechanism 94–96 , whereas membrane-bound membrane-type 1 MMP (MT1-MMP; also known as MMP14) is upregulated in a HIF2-dependent manner 94,97 .…”

“…Hypoxia is associated with an increase in the expression and the activity of type IV collagen-degrading enzymes (MMP2 and MMP9) in vitro 94–96 . MMP2 and MMP9 are upregulated by hypoxia in breast and colon cancer cells via a HIF1-dependent mechanism 94–96 , whereas membrane-bound membrane-type 1 MMP (MT1-MMP; also known as MMP14) is upregulated in a HIF2-dependent manner 94,97 . In addition to collagen degradation by MMPs, hypoxic cancer cells also show increased proteolytic activity as a result of HIF-dependent increases in their expression of urokinase plasminogen activator surface receptor 98,99 (PLAUR).…”

The Interaction Between Redox and Hypoxic Signalling Pathways in the Dynamic Oxygen Environment of Cancer Cells

“…Thioredoxin enhances the invasive behavior of tumor cells by regulating MMP activity, which is required for ECM degradation [25,26]. HIF-1 over-expression during hypoxia has also been associated with ECM degradation by upregulating MMP-2 [94] and MMP-9 gene expression [95]. In a separate study, intermittent hypoxia treated A549 and H446 lung cancer cells exhibited increased invasion in comparison to normoxic cells.…”