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Updated: Mar 2, 2026
A Robust Discovery Platform for the Identification of Novel Mediators of Melanoma Metastasis
Published on: March 8, 2022
Expression and Characterization of Membrane-Type 4 Matrix Metalloproteinase (MT4-MMP) and its Different Forms in
Bettina Hieronimus1, Julian Pfohl1, Christian Busch2,3
1Institute of Biological Chemistry and Nutrition, University of Hohenheim, Stuttgart, Germany.
Background/Aims:
Membrane-type matrix metalloproteinases (MT-MMPs) are expressed on the cell surface and hydrolyze extracellular matrix components and signaling molecules by which they influence cancer cell migration and metastasis. Two of the six known MT-MMPs are anchored to the plasma membrane via a GPI anchor, one of which is MT4-MMP. Only little is known about MT4-MMP expression, synthesis, regulation and degradation.
Methods:
We analyzed several human cancer cell lines as well as tissue homogenates using Western blotting and quantitative PCR for the expression of MT4-MMP. Organelles of SK-Mel-28 cells were separated using continuous Iodixanol gradients. Glycosylation of the SK-Mel-28 protein was studied via glucosidases and site directed mutagenesis of the MT4-MMP cDNA prior to transfection.
Results:
We found the MT4-MMP highly expressed in human melanoma cell lines as well as skin and melanoma tissue samples. Three forms of MT4-MMP with molecular masses of 45 kDa, 58 kDa and 69 kDa were detected. Further, we demonstrate that the 58 kDa form is the mature protein in the cell membrane, while the 69 kDa form is its precursor found in intracellular compartments. The 69 kDa forms are processed by furin cleavage in the Golgi apparatus. Moreover, we identified Asn318 as the single N-glycosylation site of MT4-MMP.
Conclusion:
We demonstrate the novel expression of MT4-MMP in melanocytic tissues and propose a precursor/product-relationship of the different forms of MT4-MMP in melanoma cells.
Insights
Membrane-type matrix metalloproteinase 4 (MT4-MMP) is highly expressed in melanoma. This study identifies its precursor and mature forms, revealing a novel pathway for MT4-MMP processing in cancer cells.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Membrane-type matrix metalloproteinases (MT-MMPs) influence cancer cell migration and metastasis.
- MT4-MMP, a GPI-anchored MT-MMP, has poorly understood expression and regulation.
- Understanding MT4-MMP is crucial for cancer research.
Purpose of the Study:
- To investigate the expression and processing of MT4-MMP in human cancer.
- To identify the different molecular forms of MT4-MMP.
- To elucidate the synthesis and regulation of MT4-MMP.
Main Methods:
- Western blotting and quantitative PCR on cancer cell lines and tissues.
- Organelle fractionation using Iodixanol gradients.
- Analysis of glycosylation and protein processing via site-directed mutagenesis and glucosidases.
Main Results:
- MT4-MMP is highly expressed in melanoma cell lines and tissues.
- Three forms of MT4-MMP (45 kDa, 58 kDa, 69 kDa) were detected.
- The 69 kDa form is an intracellular precursor, processed by furin in the Golgi to the mature 58 kDa membrane-bound form; Asn318 is the N-glycosylation site.
Conclusions:
- MT4-MMP is novelly expressed in melanocytic tissues.
- A precursor-product relationship exists for MT4-MMP forms in melanoma.
- This study provides insights into MT4-MMP processing and regulation in cancer.
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