Squamous cell carcinoma cell aggregates escape suspension-induced, p53-mediated anoikis: fibronectin and integrin alphav mediate survival signals through focal adhesion kinase.
Squamous cell carcinoma cell aggregates escape suspension-induced, p53-mediated anoikis: fibronectin and integrin alphav mediate survival signals through focal adhesion kinase.
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发表时间：
2004
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通讯作者：
Yan Zhang;Hai Lu;P. Dazin;Y. Kapila
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作者：
Yan Zhang;Hai Lu;P. Dazin;Y. Kapila
对失巢凋亡的抵抗，或由细胞外基质（ECM）脱离触发的凋亡，延长恶性细胞的存活，促进继发部位的再附着和定殖。为了研究人类口腔鳞状细胞癌（SCC）细胞抗失巢凋亡的分子机制，我们将人类鳞状细胞癌（HSC-3）细胞悬浮培养在涂有聚甲基丙烯酸2-羟乙酯的平板上，聚甲基丙烯酸2-羟乙酯可阻断细胞外基质的进入。形成多细胞聚集体的悬浮液中的细胞具有比单细胞显著更低的凋亡水平。聚集体，而不是单个细胞，具有高水平的纤连蛋白。与环甘氨酸-甘氨酸-天冬氨酸肽或纤连蛋白阻断抗体预孵育显着增加失巢凋亡。单个细胞的整合素α（v）受体的表达明显低于聚集体。用阻断抗体或通过用反义寡核苷酸转染来阻断α（v）功能增加了细胞凋亡并抑制了聚集。在单个细胞中，而不是聚集体中，整合素相关的粘着斑激酶（FAK）在酪氨酸397处的磷酸化减少，p53水平增加。用反义寡核苷酸阻断FAK可增加细胞凋亡，阻断p53可减少细胞凋亡。这些发现表明SCC细胞通过形成多细胞聚集体来逃避悬浮诱导的失巢凋亡，所述聚集体利用由整合素α（v）介导的纤连蛋白存活信号。由于FAK磷酸化降低和p53水平增加，悬浮液中不形成聚集体的单个细胞经历失巢凋亡。因此，SCC细胞似乎利用邻近细胞和ECM分子FN来促进转移表型。
Resistance to anoikis, or apoptosis triggered by detachment from the extracellular matrix (ECM), lengthens the survival of malignant cells, facilitating reattachment and colonization of secondary sites. To examine the molecular mechanisms underlying resistance to anoikis in human oral squamous cell carcinoma (SCC) cells, we cultured human squamous carcinoma (HSC-3) cells in suspension on plates coated with poly-2-hydroxyethyl methacrylate, which blocks access to the ECM. Cells in suspension that formed multicellular aggregates had significantly lower levels of apoptosis than single cells. Aggregates, but not single cells, had high levels of fibronectin. Preincubation with a cyclic arginine-glycine-aspartic acid peptide or fibronectin-blocking antibody significantly increased anoikis. Single cells had markedly lower expression of the integrin alpha(v) receptor than aggregates. Blocking alpha(v) function with a blocking antibody or by transfection with an antisense oligonucleotide increased apoptosis and inhibited aggregation. In single cells but not aggregates, phosphorylation of the integrin-associated focal adhesion kinase (FAK) at tyrosine 397 was reduced, and p53 levels were increased. Apoptosis was increased by blocking FAK with an antisense oligonucleotide and reduced by blocking p53. These findings show that SCC cells escape suspension-induced anoikis by forming multicellular aggregates that avail themselves of fibronectin survival signals mediated by integrin alpha(v). Single cells in suspension that do not form aggregates undergo anoikis because of decreased FAK phosphorylation and increased p53 levels. Thus, SCC cells appear to use neighboring cells and the ECM molecule FN to promote the metastatic phenotype.