Chu Y W, Seftor E A, Romer L H, Hendrix M J
Cancer Biology Program, Arizona Cancer Center, University of Arizona, Tucson, USA.
Am J Pathol. 1996 Jan;148(1):63-9.
Intermediate filaments have been used as cell-type-specific markers in differentiation and pathology; however, recent reports have demonstrated the coexpression of vimentin (a mesenchymal marker) and keratins (epithelial markers) in numerous neoplasms, including melanoma, which has been linked to metastatic disease. To test the hypothesis that coexpression of vimentin and keratins by melanoma cells contributes to a more migratory and invasive phenotype, we co-transfected a vimentin-positive human melanoma cell line, A375P (of low invasive ability), with cDNAs for keratins 8 and 18. The resultant stable transfectants expressed vimentin- and keratin-positive intermediate filaments showed a two- to threefold increase in their invasion of basement membrane matrix and migration through gelatin in vitro. These findings were further corroborated by video cinematography. During attachment and spreading on fibronectin, the transfectants containing vimentin and keratins 8 and 18 demonstrated an increase in focal adhesions that stained positive for beta 1 integrin and phosphotyrosine, along with enhanced membrane ruffling and actin stress fiber formation. From these data, we postulate that coexpression of vimentin and keratins results in increased cytoskeletal interactions at focal contacts within extracellular matrices involving integrin cell signaling events, which contributes to a more migratory behavior.
中间丝已被用作分化和病理学中细胞类型特异性标志物；然而，最近的报道表明波形蛋白（一种间充质标志物）和角蛋白（上皮标志物）在包括黑色素瘤在内的众多肿瘤中共同表达，这与转移性疾病有关。为了验证黑色素瘤细胞中波形蛋白和角蛋白的共同表达有助于形成更具迁移性和侵袭性表型这一假说，我们将波形蛋白阳性的低侵袭能力人黑色素瘤细胞系A375P与角蛋白8和18的cDNA共转染。所得稳定转染子表达波形蛋白和角蛋白阳性的中间丝，其对基底膜基质的侵袭和体外通过明胶的迁移增加了两到三倍。这些发现通过视频电影摄影得到进一步证实。在纤连蛋白上附着和铺展过程中，含有波形蛋白以及角蛋白8和18的转染子显示粘着斑增加，β1整合素和磷酸酪氨酸染色呈阳性，同时膜皱褶和肌动蛋白应力纤维形成增强。根据这些数据，我们推测波形蛋白和角蛋白的共同表达导致细胞外基质内粘着接触处细胞骨架相互作用增加，涉及整合素细胞信号转导事件，这有助于形成更具迁移性的行为。
