Down-regulation of lysyl oxidase-induced tumorigenic transformation in NRK-49F cells characterized by constitutive activation of Ras proto-oncogene
Down-regulation of lysyl oxidase-induced tumorigenic transformation in NRK-49F cells characterized by constitutive activation of Ras proto-oncogene
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DOI：
10.1074/jbc.m101695200
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发表时间：
2001-08-03
影响因子：
4.8
通讯作者：
Di Donato, A
中科院分区：
文献类型：
--
作者：
Giampuzzi, M;Botti, G;Di Donato, A
一些研究表明赖氨酸氧化酶可能具有肿瘤抑制作用，因为它在许多人类和癌基因诱导的肿瘤中下调。为了解决这个问题，我们在正常大鼠肾成纤维细胞中通过以反义方向稳定转染其cDNA来下调该酶。所选的克隆显示赖氨酸氧化酶的缺失和显著的表型变化，可解释为转化的迹象。反义赖氨酸氧化酶克隆在裸鼠中表现出松散附着和不依赖锚定生长的特点，具有较高的致瘤性。此外，我们发现PDGF和IGF-1受体对其配体的反应受损。特别是，转化后的细胞表现出PDGF受体的下调，并表达了正常对照细胞中不存在的IGF-1 β受体的105-kDa亚型。缺乏对PDGF-BB的反应已被描述为许多ras转化表型的特征。因此，我们研究了p21（ras）的状态。事实上，我们发现在稳态生长和长时间饥饿期间，活性p21（ras）的水平都显著升高。我们的数据揭示了赖氨酸氧化酶肿瘤抑制活性的新证据，突出了它在控制Ras激活和生长因子依赖中的特殊作用。
Several investigations have suggested a putative tumor suppressor role for lysyl oxidase because it is downregulated in many human and oncogene-induced tumors. To address this issue we down-regulated the enzyme in normal rat kidney fibroblasts by stable transfection of its cDNA in an antisense orientation. The selected clones revealed an absence of lysyl oxidase and dramatic phenotypic changes, interpretable as signs of transformation. The antisense lysyl oxidase clones showed, indeed, loose attachment to the plate and anchorage-independent growth and were highly tumorigenic in nude mice. Moreover, we found an impaired response of the PDGF and IGF-1 receptors to their ligands. In particular, the transformed cells showed a down-regulation of both PDGF receptors and expressed the 105-kDa isoform of the IGF-1 beta receptor, which was not present in the normal control cells. The lack of response to PDGF-BB has been described as a feature of many ras-transformed phenotypes. Therefore, we looked at the status of the p21(ras). Indeed, we found a significantly higher level of active p21(ras) both during steady-state growth and prolonged starvation. Our data reveal new evidence for a tumor suppressor activity of lysyl oxidase, highlighting its particular role in controlling Ras activation and growth factor dependence.