MMP8 increases tongue carcinoma cell–cell adhesion and diminishes migration via cleavage of anti-adhesive FXYD5
K. Juurikka,
A. Dufour,
K. Pehkonen,
B. Mainoli,
P. Campioni Rodrigues,
N. Solis,
T. Klein,
P. Nyberg,
C. M. Overall,
T. Salo,
P. Åström
Affiliations
K. Juurikka
Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu
A. Dufour
Department of Physiology & Pharmacology, University of Calgary
K. Pehkonen
Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu
B. Mainoli
Department of Physiology & Pharmacology, University of Calgary
P. Campioni Rodrigues
Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu
N. Solis
Department of Oral Biological and Medical Sciences, Faculty of Dentistry, Centre for Blood Research, and Department of Biochemistry and Molecular Biology, University of British Columbia
T. Klein
Department of Oral Biological and Medical Sciences, Faculty of Dentistry, Centre for Blood Research, and Department of Biochemistry and Molecular Biology, University of British Columbia
P. Nyberg
Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu
C. M. Overall
Department of Oral Biological and Medical Sciences, Faculty of Dentistry, Centre for Blood Research, and Department of Biochemistry and Molecular Biology, University of British Columbia
T. Salo
Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu
P. Åström
Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu
Abstract Matrix metalloproteinases (MMPs) modify bioactive factors via selective processing or degradation resulting in tumour-promoting or tumour-suppressive effects, such as those by MMP8 in various cancers. We mapped the substrates of MMP8 to elucidate its previously shown tumour-protective role in oral tongue squamous cell carcinoma (OTSCC). MMP8 overexpressing (+) HSC-3 cells, previously demonstrated to have reduced migration and invasion, showed enhanced cell-cell adhesion. By analysing the secretomes of MMP8 + and control cells with terminal amine isotopic labelling of substrates (TAILS) coupled with liquid chromatography and tandem mass spectrometry (LC-MS/MS), we identified 36 potential substrates of MMP8, including FXYD domain-containing ion transport regulator 5 (FXYD5). An anti-adhesive glycoprotein FXYD5 has been previously shown to predict poor survival in OTSCC. Cleavage of FXYD5 by MMP8 was confirmed using recombinant proteins. Furthermore, we detected a loss of FXYD5 levels on cell membrane of MMP8 + cells, which was rescued by inhibition of the proteolytic activity of MMP8. Silencing (si) FXYD5 increased the cell-cell adhesion of control but not that of MMP8 + cells. siFXYD5 diminished the viability and motility of HSC-3 cells independent of MMP8 and similar effects were seen in another tongue cancer cell line, SCC-25. FXYD5 is a novel substrate of MMP8 and reducing FXYD5 levels either with siRNA or cleavage by MMP8 increases cell adhesion leading to reduced motility. FXYD5 being a known prognostic factor in OTSCC, our findings strengthen its potential as a therapeutic target.