Juurikka K, Dufour A, Pehkonen K, Mainoli B, Campioni Rodrigues P, Solis N, Klein T, Nyberg P, Overall C M, Salo T, Åström P
Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu, Oulu, Finland.
Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.
Oncogenesis. 2021 May 31;10(5):44. doi: 10.1038/s41389-021-00334-x.
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.
基质金属蛋白酶（MMPs）通过选择性加工或降解来修饰生物活性因子，从而产生促肿瘤或抑肿瘤作用，如MMP8在各种癌症中的作用。我们绘制了MMP8的底物图谱，以阐明其先前在口腔舌鳞状细胞癌（OTSCC）中显示的肿瘤保护作用。过表达MMP8（+）的HSC-3细胞先前已证明其迁移和侵袭能力降低，且显示出增强的细胞间粘附。通过使用底物末端胺同位素标记（TAILS）结合液相色谱和串联质谱（LC-MS/MS）分析MMP8 +细胞和对照细胞的分泌蛋白组，我们鉴定出36种MMP8的潜在底物，包括含FXYD结构域的离子转运调节因子5（FXYD5）。先前已证明抗粘附糖蛋白FXYD5可预测OTSCC患者的不良生存情况。使用重组蛋白证实了MMP8对FXYD5的切割作用。此外，我们检测到MMP8 +细胞细胞膜上FXYD5水平降低，而抑制MMP8的蛋白水解活性可使其恢复。沉默（si）FXYD5可增加对照细胞的细胞间粘附，但对MMP8 +细胞无此作用。siFXYD5降低了HSC-3细胞的活力和运动能力，且与MMP8无关，在另一种舌癌细胞系SCC-25中也观察到了类似的效果。FXYD5是MMP8的新型底物，并通过siRNA降低FXYD5水平或由MMP8切割均可增加细胞粘附，从而降低运动能力。鉴于FXYD5是OTSCC中已知的预后因素，我们的研究结果强化了其作为治疗靶点的潜力。
