An altered fibronectin matrix induces anoikis of human squamous cell carcinoma cells by suppressing integrin alpha v levels and phosphorylation of FAK and ERK
An altered fibronectin matrix induces anoikis of human squamous cell carcinoma cells by suppressing integrin alpha v levels and phosphorylation of FAK and ERK
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DOI：
10.1007/s10495-007-0138-9
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发表时间：
2007-12-01
期刊：
影响因子：
7.2
通讯作者：
Kapila, Yvonne L.
中科院分区：
文献类型：
--
作者：
Kamarajan, Pachiyappan;Kapila, Yvonne L.
纤连蛋白调节许多细胞过程，包括迁移、增殖、分化和存活。先前，我们发现鳞状细胞癌（SCC）细胞聚集体通过黏着斑激酶（FAK）参与纤连蛋白介导的生存信号，从而逃避悬浮诱导的p53介导的失巢凋亡。在这里，我们报告了一种改变的基质，由突变的，无功能的高亲和力肝素结合结构域和纤连蛋白的V区（V+H-）组成，诱导人SCC细胞的失巢凋亡;这种反应被半胱天冬酶-8和半胱天冬酶-3抑制剂阻断。失巢凋亡是由一组SCC细胞中整合素α v的下调介导的，并且被证明是蛋白酶体依赖性的。整合素α v或FAK的过表达抑制了caspase-3活化和凋亡的增加，而α v或FAK的抑制触发了凋亡的进一步显著增加，表明凋亡是由整合素α v水平的抑制和FAK的去磷酸化介导的。V+H-处理降低了细胞外信号调节激酶（ERK）1和2的磷酸化，并通过组成性激活ERK激酶MEK 1直接激活ERK，增加ERK 1和ERK 2磷酸化，抑制V+H-诱导的细胞凋亡增加。ERK作用于α v和FAK信号的下游，因为α v和FAK过表达抑制了ERK磷酸化的减少和V+H-触发的失巢凋亡的增加。这些发现提供了证据表明，与纤连蛋白V区相关的高亲和力肝素结合结构域的突变，或纤连蛋白基质的改变，通过调节整合素α v介导的FAK和ERK磷酸化诱导人SCC细胞的失巢凋亡。
Fibronectin regulates many cellular processes, including migration, proliferation, differentiation, and survival. Previously, we showed that squamous cell carcinoma (SCC) cell aggregates escape suspension-induced, p53- mediated anoikis by engaging in fibronectin-mediated survival signals through focal adhesion kinase (FAK). Here we report that an altered matrix, consisting of a mutated, nonfunctional high- affinity heparin- binding domain and the V region of fibronectin (V+H-), induced anoikis in human SCC cells; this response was blocked by inhibitors of caspase-8 and caspase-3. Anoikis was mediated by down-regulation of integrin alpha v in a panel of SCC cells and was shown to be proteasome-dependent. Overexpression of integrin alpha v or FAK inhibited the increase in caspase-3 activation and apoptosis, whereas suppression of alpha v or FAK triggered a further significant increase in apoptosis, indicating that the apoptosis was mediated by suppression of integrin alpha v levels and dephosphorylation of FAK. Treatment with V+H- decreased the phosphorylation of extracellular signal-regulated kinase (ERK) 1 and 2, and direct activation of ERK by constitutively active MEK1, an ERK kinase, increased ERK1 and ERK2 phosphorylation and inhibited the increase in apoptosis induced by V+H-. ERK acted downstream from alpha v and FAK signals, since alpha v and FAK overexpression inhibited both the decrease in ERK phosphorylation and the increase in anoikis triggered by V+H-. These findings provide evidence that mutations in the high-affinity heparin-binding domain in association with the V region of fibronectin, or altered fibronectin matrices, induce anoikis in human SCC cells by modulating integrin alpha v-mediated phosphorylation of FAK and ERK.