Hypoxia-inducible factor-1α polymorphisms and TSC1/2 mutations are complementary in head and neck cancers
Hypoxia-inducible factor-1α polymorphisms and TSC1/2 mutations are complementary in head and neck cancers
复制标题
DOI：
10.1186/1476-4598-5-3
复制
发表时间：
2006-01-16
期刊：
影响因子：
37.3
通讯作者：
Sauk, John J.
中科院分区：
文献类型：
--
作者：
Hebert, Carla;Norris, Kathleen;Sauk, John J.
背景资料：低氧诱导因子-1 α（HIF-1 α）的多态性或突变增加了其在常氧下的活性和稳定性。同样地，通过TSC 1或TSC 2的损失而破坏TSC 1/TSC 2复合物已显示导致HIF-1 α的异常积累。在这里，我们研究了外显子12的新多态性，该多态性近似于5个细胞系和28例口腔鳞癌患者中HIF-1 α的氧依赖性降解结构域。此外，我们评估存在的多态性和突变TSC 1和TSC 2，以确定如果失调，这种可能补充HIF-1 α expression.Results：变性高压液相色谱（DHPLC）分析28例口腔鳞癌患者HIF-1 α的第12外显子的PCR片段显示，28例患者中有6个不匹配的异源双链模式。从外周血白细胞中提取基因组DNA，直接测序显示，在6例中，5例这些变化代表多态性，而1例是体细胞突变。TSC 1和TSC 2的分析显示外显子中存在异源双链体：TSC 1外显子17; TSC 2外显子36、40和41。具有HIF-1 α多态性或外显子12内突变的肿瘤中HIF-1 α的相对水平显著更高，而具有TSC 1/TSC 2缺失或多态性的肿瘤显示出HIF-1 α水平更高的趋势。对5种SCC细胞系中HIF-1 α、TSC 1和TSC 2的Western印迹分析显示，在具有TSC 1和/或TSC 2突变的SCC细胞中，HIF-1 α的水平较高。用siRNA靶向TSC 2的野生型TSC 2细胞表现出增加的HIF-1 α水平。HIF-1 α突变体的转染在TSC 1/TSC 2突变细胞系中产生比野生型细胞更高水平的HIF-1 α。施用雷帕霉素的TSC 1/TSC 2突变体细胞系阻断了S6磷酸化，并将HIF-1 α水平降低至野生型TSC 1/TSC 2细胞系中观察到的水平。TSC 1/TSC 2复合物的失调通过突变互补HIF-1 α在头颈部SCC中表达的多态性，并可提供生物标记物以预测对特定疗法的反应和总体疾病预后。
Background: Polymorphisms or mutations in hypoxia inducible factor-1 alpha (HIF-1alpha) that increases its activity and stability under normoxia have recently been identified. Likewise, disruption of the TSC1/TSC2 complex through loss of TSC1 or TSC2 has been shown to result in abnormal accumulation of HIF-1 alpha. Here, we investigate the novel polymorphisms in exon 12, that approximate the oxygen-dependent degradation domain of HIF-1alpha in five cell lines and 28 patients with oral squamous carcinomas. Moreover, we assess for the presence of polymorphisms and mutations in TSC1 and TSC2, to ascertain if dysregulation of such might complement HIF-1alpha expression.Results: Denaturing high pressure liquid chromatography (DHPLC) analysis on PCR fragments in exon 12 of HIF-1alpha from 28 patients with OSCC revealed that 6 of 28 patients had mismatched heteroduplex patterns. Genomic DNA was extracted from peripheral blood leukocytes and direct sequencing showed that in 5 of the six cases these changes represented polymorphisms while, one case was a somatic mutation. Analyses of TSC1 and TSC2 revealed heteroduplexes in exons: TSC1 exon 17; TSC2 exons 36,40, and 41. The relative levels of HIF-1alpha were significantly greater for tumors possessing a HIF-1alpha polymorphism or mutation within exon 12, whereas tumors possessing a deletion or polymorphism in TSC1/TSC2 displayed a trend for higher levels of HIF1alpha. Western blot analyses for HIF-1alpha, TSC1 and TSC2 in five SCC cell lines revealed high levels of HIF-1alpha in SCC cells possessing TSC1 and/or TSC2 mutations. Wild-type TSC2 cells targeted with siRNA to TSC2 exhibited increased levels of HIF-1alpha. Transfection of a HIF-1alpha mutant produced higher levels of HIF-1alpha in TSC1/TSC2 mutant cell lines than in wild type cells. TSC1/TSC2 mutant cell lines administered Rapamycin blocked S6 phorphorylation and diminished the levels of HIF-1alpha to those observed in cell lines with wild type TSC1/TSC2.Conclusion: Dysregulation of the TSC1/TSC2 complex by mutation compliments HIF-1 alpha polymorphisms in the expression of HIF-1alpha in SCC of the head and neck, and may provide biomarkers to predict responses to specific therapies and overall disease prognosis.