Regulation of adhesion molecule integrins by membrane-bound proteinase ADAM

ADAM是由金属蛋白酶和去整合素组成的膜结合分子。为了阐明ADAM分子在肺癌细胞EBC-1脑转移亚系和骨转移亚系中的表达，探讨ADAM分子在肺癌转移中的作用。结果表明，ADAM9在脑转移亚系中的表达水平明显高于骨转移亚系或亲本细胞系。将ADAM9基因转入Kung癌A549细胞，可增加NGF刺激的侵袭活性，增加对脑组织切片的粘附力，上调整合素a3b1的表达。转染组和亲本细胞系在其他整合素表达水平上无明显差异。当通过尾静脉接种到滑行小鼠的尾静脉时，转染体诱导了大量肺和脑转移。另一方面，亲本细胞或模拟转染体诱导了大量的肺转移，但没有引起脑转移。将ADAM9基因导入HT1080纤维肉瘤HT1080细胞，流式细胞仪分析表明，只有整合素A4在转染体中消失，而亲本细胞或模型细胞表达整合素A4。转基因细胞与整合素a4b1的配体CS-1多肽或血管细胞黏附分子-1(VCAM-1)的粘附性降低。对CS-1或VCAM-1的迁移或侵袭活性也降低。将亲本细胞接种于裸小鼠尾静脉，可诱导大量肺转移，但转染者肺转移明显减少。皮下注射后肿瘤组织中ADAM9的表达无明显差异，提示ADAM9可能在整合素表达及肿瘤转移中起一定作用。

ADAM is membrane-bound molecules composed of metalloproteinase and disintegrin. Expression of ADAM molecules of highly brain-metastatic subline and bone-metastatic subline from lung cancer cell EBC-1 cells are studied in order to clarify the implication of ADAM in cancer metastasis. As a result the expression level of ADAM9 mRNA was upregulated in brain-metastatic subline than those in bone-metastatic subline or parental cell line. Transfection of ADAM9 cDNA in kung cancer A549 cell resulted in increased NGF-stimulated invasive activity, elevated adhesion to brain tissue slices and upregulation of integrin a3b1 expression. There were no differences between transfectant and parental cell line in other integrin expression levels. When inoculated intravenously to the tail vein in skid mice, transfectants induced numerous lung and brain metastases. On the other hand parental cells or mock transfectant induced plenty of lung metastases, but not brain metastasis. These results suggested ADAM9 might play a role in brain metastasis of lung cancer.Transfection of ADAM9 cDNA in fibrosarcoma HT1080 cell was preformed and FACS analysis of each integrin expression showed disappearance of only integrin a4 in transfectants while parental cell or mock transfectant expressed integrin a4. Decreased adhesion of transfectants to CS-1 peptide or VCAM-1 (vascular cell adhesion molecule-1), both of which are ligands of integrin a4b1, was observed. Migratory or invasive activity to CS-1 or VCAM-1 was also reduced. When inoculated intravenously to tail vein of nude mice, parent cells induced a number of lung metastases but marked decreased lung metastases were found in transfectants. There were no differences in the tumor after subcutaneous injection.These data suggested ADAM9 might play some roles in integrin expression and also in cancer metastasis.