Sun Guan, Cao Ying, Guo Jun, Li Min, Dai Yuyu
Department of Neurosurgery, Yancheng City No.1 People's Hospital, The Fourth Affiliated Hospital of Nantong University, Yancheng, People's Republic of China.
Department of Ear-Nose-Throat, The Second People's Hospital of Huai'an, Huai'an Affiliated Hospital of Xuzhou Medical University, Huai'an, People's Republic of China.
Cancer Manag Res. 2020 Feb 11;12:981-991. doi: 10.2147/CMAR.S235791. eCollection 2020.
Glioblastoma is one of the most common malignant cancers worldwide. In our previous work, we have shown that heat shock cognate protein 70 (Hsc70) functions as a positive growth regulator in glioma. We investigated the role of Hsc70 in integrin β1 mediated invasion of glioma cells.
In order to investigate whether the down-regulation of Hsc70 would affect the expression of integrin β1 subunit, HeLa cells were transiently transfected with Hsc70-AS or pcDNA3.0 vectors and the down-regulation of Hsc70 was confirmed by Western blotting. Human brain glioma U87 cells were stably transfected with Hsc70-AS or pcDNA3.0 vectors to further elucidate the relationship between Hsc70 and integrin β1 in human glioma cells. Cellular localization of integrin β1 was detected using immunofluorescence confocal microscopy analysis.
Here we reported that down-regulation of the expression of Hsc70 in U87 cells by transfection with antisense cDNA specifically increased the expression of cell surface integrin β1 without changing its mRNA. Meanwhile, the integrin β1 125-kD mature form increased while 105-kD precursor form decreased when Hsc70 was down-regulated. Mechanically, the U87 cells transfected with antisense cDNA of Hsc70 decreased the Golgi localization of integrin β1, strengthened its interaction with integrin α5 subunit, and enhanced the adhesion ability to fibronectin (FN) and the phosphorylation level of focal adhesion kinase (FAK).
Overall, these results suggested that the down-regulation of Hsc70 expression could promote the expression of cell surface integrin β1 and subsequently inhibit glioma invasion phenotype.
胶质母细胞瘤是全球最常见的恶性肿瘤之一。在我们之前的研究中，我们已经表明热休克同源蛋白70（Hsc70）在胶质瘤中作为一种正向生长调节因子发挥作用。我们研究了Hsc70在整合素β1介导的胶质瘤细胞侵袭中的作用。
为了研究Hsc70的下调是否会影响整合素β1亚基的表达，将HeLa细胞用Hsc70-AS或pcDNA3.0载体进行瞬时转染，并通过蛋白质印迹法确认Hsc70的下调。将人脑胶质瘤U87细胞用Hsc70-AS或pcDNA3.0载体进行稳定转染，以进一步阐明人胶质瘤细胞中Hsc70与整合素β1之间的关系。使用免疫荧光共聚焦显微镜分析检测整合素β1的细胞定位。
在此我们报道，通过反义cDNA转染下调U87细胞中Hsc70的表达可特异性增加细胞表面整合素β1的表达，而不改变其mRNA。同时，当Hsc70下调时，整合素β1的125-kD成熟形式增加而105-kD前体形式减少。机制上，用Hsc70反义cDNA转染的U87细胞降低了整合素β1的高尔基体定位，增强了其与整合素α5亚基的相互作用，并增强了对纤连蛋白（FN）的粘附能力和粘着斑激酶（FAK）的磷酸化水平。
总体而言，这些结果表明Hsc70表达的下调可促进细胞表面整合素β1的表达，随后抑制胶质瘤侵袭表型。
