Selective down-regulation of integrin receptors in spheroids of squamous cell carcinoma.
Selective down-regulation of integrin receptors in spheroids of squamous cell carcinoma.
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发表时间：
1994-02
期刊：
影响因子：
11.2
通讯作者：
N. Waleh;J. Gallo;T. D. Grant;B. Murphy;R. Kramer;R. Sutherland
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文献类型：
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作者：
N. Waleh;J. Gallo;T. D. Grant;B. Murphy;R. Kramer;R. Sutherland
据报道，整合素在鳞状细胞癌中的表达在体内下调。由于整合素是其功能包括细胞骨架重组以响应周围细胞外基质的分子，我们检测了转化细胞系A431在以多细胞球状或单层形式生长时整合素的表达。球体被生长到大约100微米和大约600微米的尺寸。由于较大的A431球体需要表皮生长因子才能生长，我们还研究了这种生长因子对单层或小球体生长细胞中整合素表达的影响。使用针对α6、β1和β4亚单位的单抗的免疫染色研究显示，在球体的外围有一种强烈的染色模式。球体内部细胞与β1抗体呈中度阳性反应，但较外围细胞明显减少。另一方面，抗阿尔法2抗体显示球体细胞周围有均匀的染色。Western印迹分析证实，与单层相比，球体中的α6和β1蛋白水平总体上有所降低。Northern印迹分析表明，整合素亚单位α6、β1和β4在球体中的低表达是由于mRNA转录减少所致。然而，Northern印迹分析表明，α2、α5或β5mRNA的表达没有显著变化。相反，αv在球体中的表达略有减少。在单层或球体生长的细胞中，表皮生长因子增加了α2、α6、β1和β4整合素亚基的mRNA表达，而对αv或β5的表达没有明显影响。这些结果模拟了体内发现的表达模式，表明细胞与细胞的接触和球体内细胞的微环境调节了整合素分子的亚组的表达和分布。
Integrin expression in squamous cell carcinomas have been reported to be down-regulated in vivo. Because integrins are molecules whose functions include the reorganization of cytoskeleton in response to the surrounding extracellular matrix, we have examined the expression of integrins in the transformed cell line A431 when grown as multicellular spheroids or as monolayers. The spheroids were grown to sizes of approximately 100 microns and approximately 600 microns. Since larger A431 spheroids require epidermal growth factor for growth, we also investigated the effect of this growth factor on the expression of integrins in cells grown as monolayers or as small spheroids. Immunostaining studies using monoclonal antibodies specific for alpha 6, beta 1, and beta 4 subunits revealed a strong staining pattern in the periphery of the spheroids. The interior cells of the spheroids showed a moderate, positive reaction with the beta 1 antibody but significantly reduced from that at the periphery. Anti-alpha 2 antibody, on the other hand, revealed a uniform staining around the cells throughout the spheroids. Western blot analyses confirmed an overall diminution of alpha 6 and beta 1 protein levels in the spheroids compared with monolayers. Northern blot analyses showed that the low expression of integrin subunits alpha 6, beta 1, and beta 4 in spheroids was due to a reduction in mRNA transcripts. Northern blot analyses, however, showed no significant change in the expressions of alpha 2, alpha 5, or beta 5 mRNA. Conversely, the expression of alpha v was slightly reduced in spheroids. Epidermal growth factor increased the mRNA expression of alpha 2, alpha 6, beta 1, and beta 4 integrin subunits in cells grown either as monolayers or as spheroids whereas epidermal growth factor had no detectable effect on the expression of alpha v or beta 5. These results mimic the pattern of expression found in vivo and indicate that cell-cell contact and the microenvironments of cells within a spheroid regulate the expression and distribution of a subset of integrin molecules.