Targeting the Warburg Effect That Arises in Tumor Cells Expressing Membrane Type-1 Matrix Metalloproteinase

Takeharu Sakamoto,Daigo Niiya,Motoharu Seiki

doi:10.1074/jbc.m110.188714

Takeharu Sakamoto, Daigo Niiya + Show 1 more

Open Access

https://doi.org/10.1074/jbc.m110.188714

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Abstract

Hypoxia inducible factor-1 (HIF-1) is a key transcription factor required for cellular adaptation to hypoxia, although its physiological roles and activation mechanisms during normoxia have not been studied sufficiently. The Warburg effect, which is a hallmark of malignant tumors that is characterized by increased activity of aerobic glycolysis, accompanies activation of HIF-1 during normoxia. Besides tumor cells that have multiple genetic and epigenetic alterations, normal macrophages also use glycolysis for ATP production by depending upon elevated HIF-1 activity even during normoxia. We recently found that activity of factor inhibiting HIF-1 (FIH-1) is specifically suppressed in macrophages by a nonproteolytic activity of membrane type-1 matrix metalloproteinase (MT1-MMP/MMP-14). Thus, MT1-MMP expressed in macrophages plays a significant role in regulating HIF-1 activity during normoxia. In the light of this finding, we examined here whether MT1-MMP contributes to the Warburg effect of tumor cells. All the tumor cell lines that express MT1-MMP exhibit increased glycolytic activity, and forced expression of MT1-MMP in MT1-MMP-negative tumor cells is sufficient to induce the Warburg effect. The cytoplasmic tail of MT1-MMP mediates the stimulation of aerobic glycolysis by increasing the expression of HIF-1 target genes. Specific intervention of the MT1-MMP-mediated activation of HIF-1 in tumor cells retarded tumor growth in mice. Systemic administration of a membrane-penetrating form of the cytoplasmic tail peptide in mice to inhibit HIF-1 activation competitively also exhibited a therapeutic effect on tumors.

Highlights

Hypoxia inducible factor-1 (HIF-1) is a master transcription factor that mediates the adaptation of cells to hypoxia and directs cells to produce ATP via anaerobic glycolysis, and its activity is suppressed during normoxia by post-translational mechanisms, and this suppression is released by lowering of the oxygen levels [1,2,3]
The results indicate that the glycolytic activity of MCF-7 cells responds to hypoxic conditions, whereas the glycolytic activity of MDA-MB-231 cells during normoxia is already close to the upper limit of the capacity of the cell
We demonstrated that tumor cells expressing MT1-MMP exhibited enhanced glycolytic activity that is similar to the level observed when cells are exposed to hypoxia in culture

Summary

Introduction

We tested whether knockdown of the expression of MT1-MMP, Mint3, or FIH-1 affected the glycolytic activity of MDA-MB231 cells using specific siRNA sequences (Fig. 1, C and D). In contrast to the results with MDA-MB231 cells, transfection of MCF-7 cells with siRNA targeting Mint3 or MT1-MMP had no effect on lactate production during normoxia, whereas knockdown of FIH-1 expression in these cells increased lactate production by 1.6-fold, suggesting that FIH-1 is active in these cells, inhibits HIF-1 activity, and thereby suppresses glycolysis (Fig. 1D, normoxia).

Results

Conclusion