Inhibition of proprotein convertases is associated with loss of growth and tumorigenicity of HT-29 human colon carcinoma cells -: Importance of insulin-like growth factor-1 (IGF-1) receptor processing in IGF-1-mediated functions
Inhibition of proprotein convertases is associated with loss of growth and tumorigenicity of HT-29 human colon carcinoma cells -: Importance of insulin-like growth factor-1 (IGF-1) receptor processing in IGF-1-mediated functions
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DOI：
10.1074/jbc.m101725200
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发表时间：
2001-08-17
影响因子：
4.8
通讯作者：
Seidah, NG
中科院分区：
文献类型：
--
作者：
Khatib, AM;Siegfried, G;Seidah, NG
枯草杆菌蛋白酶/kexin家族的前蛋白转化酶（PC）负责激素原、促生长因子及其受体的活化。我们试图确定PC介导的活性的丧失是否可能影响癌细胞的恶性表型。在模型HT-29细胞（HT-29/PDX）和其它细胞系中分析编码有效PC抑制剂的α（1）-抗胰蛋白酶波特兰（α（1）-PDX）cDNA的稳定转染子。α（1）-PDX的表达导致胰岛素样生长因子-1受体原（pro-IGF-IR）加工阻断，从而抑制外源性IGF-1诱导其β亚基和胰岛素相关底物-1的酪氨酸磷酸化的能力。在弗林蛋白酶缺陷的LoVo-C5细胞中，IGF-1 R与四种不同的PC或新型转化酶SKI-1的共表达表明，pro-IGF-1 R（类似于200 kDa）裂解成IGF-1 R（β亚基，类似于105 kDa）可以通过弗林蛋白酶和PC 5A实现，但不能通过PACE 4、PC 7或SKI-1实现。α（1）-PDX的表达导致DNA合成减少和锚定非依赖性生长。血清剥夺后，α（1）-PDX转染子表现出增强的凋亡表型，对IGF-1介导的[H-3]胸苷掺入和抗凋亡保护不敏感。这些细胞表现出降低的侵袭力，从而导致尿激酶型纤溶酶原激活物及其受体、组织型纤溶酶原激活物和纤溶酶原激活物抑制剂-1的mRNA水平降低。裸鼠皮下接种细胞的比较显示，注射HT-29/PDX细胞的动物表现出延迟和较低的肿瘤发生率以及减小的肿瘤大小。CD 31抗原表达的免疫组织化学分析，内皮细胞的标志物，显示减少HT-29/PDX肿瘤血管化。这些研究结果表明，PC积极促进HT-29肿瘤的生长和恶性表型，这表明PC抑制策略可能是一个有用的加合物的阿森纳的结直肠癌基因治疗。
Proprotein convertases (PCs) of the subtilisin/kexin family are responsible for the activation of prohormones, protrophic factors, and their receptors. We sought to determine whether loss of PC-mediated activities might affect the malignant phenotypes of cancer cells. Stable transfectants of alpha (1)-antitrypsin Portland (alpha (1)-PDX) cDNA, coding for a potent PC inhibitor, were analyzed in model HT-29 cells (HT-29/PDX) and in other cell lines. Expression of alpha (1)-PDX resulted in a proinsulin-like growth factor-1 receptor (pro-IGF-IR) processing blockade, hence inhibiting the ability of exogenous IGF-1 to induce tyrosine phosphorylation of its beta -subunit and insulin-related substrate-1. Coexpression of IGF-1R with four different PCs or the novel convertase SKI-1 in the furin-defective LoVo-C5 cells demonstrated that pro-IGF-1R (similar to 200 kDa) cleavage into IGF-1R (beta -subunit, similar to 105 kDa) can be achieved by furin and PC5A, but not by PACE4, PC7, or SKI-1. Expression of alpha (1)-PDX resulted in reduction of DNA synthesis and in anchorage-independent growth. Following serum deprivation, the alpha (1)-PDX transfectants exhibited an enhanced apoptotic phenotype and were insensitive to IGF-1-mediated [H-3]thymidine incorporation and protection against apoptosis. These cells showed reduced invasiveness that paralleled decreased mRNA levels of urokinase-type plasminogen activator and its receptor, tissue-type plasminogen activator, and plasminogen activator inhibitor-1. Comparative subcutaneous inoculation of cells in nude mice revealed that animals injected with HT-29/PDX cells exhibited delayed and lower incidence of tumor development as well as reduced tumor size. Immunohistochemical analysis of CD31 antigen expression, a marker of endothelial cells, revealed reduced HT-29/PDX tumor vascularization. These findings indicate that PCs actively contribute to the growth and malignant phenotypes of HT-29 tumors, suggesting that PC inhibition strategies may be a useful adduct to the arsenal of colorectal anticancer gene therapies.