Possible Mechanism Responsible for Changes of β-dystroglycanin Oral Squamous Cell Carcinoma

目的:探讨口腔鳞癌细胞中β-DG蛋白的存在状态及其分子机制。方法:在检测口腔鳞癌四株细胞系中β-DG蛋白存在状态的基础上,应用Western blot和蛋白质测序法研究基质金属蛋白酶(MMP)抑制剂1,10-phenanthroline对β-DG蛋白降解和癌细胞侵袭能力的逆转作用。结果:口腔鳞癌细胞中β-DG蛋白发生了降解,经MMP抑制剂1,10-phenanthroline作用后可以逆转β-DG蛋白降解和降低癌细胞的侵袭能力。蛋白测序证实,β-DG蛋白降解片段N端的氨基酸顺序为Ile-Asn-Thr-Asn或Ile-Val-Thr-Gln。结论:口腔鳞癌细胞中β-DG蛋白降解与癌细胞的侵袭和转移能力有关,MMP的剪切作用可能是β-DG蛋白降解的重要机制之一。

Objective： To investigate the correlation between β- dystroglycan degradation with invasiveness of tongue cancer ceils and its possible processing mechanism by MMP. Methods： β-dystroglycan degradation in SCC -4,9,15,25 was probed by western blot. Effects of MMP inhibitor 1,10- phenanthroline on the invasiveness of SCC -4,9,15,25 cell lines and β- dystroglycan degradation were investigated by in vitro invasion assay and immunoblot analysis, respectively. Coimmunoprecipitation and N - terminal sequencing were performed to determine the possible cleavage site of β- dystroglycan by MMP. Results： Western blot revealed an interesting 30 kDa fragment of β-dystroglycan （β-DG30） besides full β- dystroglycan （β- DGfull）. The N-terminal sequence of β- DG30 was detected as Ile-Ash-Thr- Ash, or lie- Val -Thr- Gin by protein sequencing. In the presence of MMP inhibiror 1,10 -phenanthroline, β -dystroglycan degradation was abolished and the number of invasive tumour cells decreased significantly compared to controls. Conclusion： β- DG degradation is possibly correlated with invasiveness of tongue cancer cells. The MMP activity is partly responsible for the processing of full β- dystroglycan into β- DG30.