Deletion, methylation, and expression of the NKX3.1 suppressor gene in primary human prostate cancer
Deletion, methylation, and expression of the NKX3.1 suppressor gene in primary human prostate cancer
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DOI：
10.1158/0008-5472.can-04-2688
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发表时间：
2005-02-15
期刊：
影响因子：
11.2
通讯作者：
Gelmann, EP
中科院分区：
文献类型：
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作者：
Asatiani, E;Huang, WX;Gelmann, EP
NKX3.1是一种前列腺特异性的同音蛋白和肿瘤抑制剂，受到前列腺癌8p21的影响。在小鼠中，NKX3.1单倍不足会导致前列腺发育不全，并补充因其他抑制基因丧失而引起的癌症形成。但是，在大多数主要前列腺癌中可以检测到NKX3.1的表达。我们研究了原发性前列腺癌中抑制基因单倍体不足，甲基化和定量NKX3.1表达水平之间的关系。通过微卫星分析，荧光原位杂交和定量PCR评估NKX3.1基因拷贝数。 NKX3.1在前列腺癌细胞系中确定基因甲基化，从而确定了组织中甲基化特异性PCR分析的潜在CpG甲基化位点。我们验证并应用了内部控制的荧光免疫显微镜测定，以从根部前列腺切除术中的48个原发性前列腺癌标本中进行NKX3.1蛋白表达。 NKT3.1在测试的43个组织中的27个中发现了杂合性的丧失。在前列腺癌细胞系或组织中，均未发现NKX3.1基因的经典CpG岛甲基化。然而，在40个测试样品中的33个中，与相邻的正常细胞相比，在恶性肿瘤中甲基甲基化的CpG位点在-921，-903和-47中被甲基化的程度更高。在48个样品中的43个中，NKX3.1蛋白表达从0.34降低到0.90，而相对于相邻的正常腔上皮（所有样品平均值为0.68; 95％置信区间，0.05）。在12例也具有高级前列腺上皮内肿瘤的病例中，NKX3.1表达水平在侵入性和浸润性癌细胞中相似，并且明显低于相邻的正常细胞。即使在存在等位基因损失的情况下，NKX3.1在前列腺切除术时在前列腺癌的广泛范围内降低了NKX3.1的表达，这表明各种因素会影响表达。癌细胞中值低于中位水平的蛋白质表达的样品既有NKX3.1缺失和选择性CpG甲基化。
NKX3.1 is a prostate-specific homeoprotein and tumor suppressor that is affected by the loss of 8p21 in prostate cancer. In mice, Nkx3.1 haploinsufficiency results in prostatic dysplasia and complements cancer formation induced by loss of other suppressor genes. However, NKX3.1 expression can be immunohistochemically detected in most primary prostate cancers. We examined the relationship between suppressor gene haploinsufficiency, methylation, and quantitative NKX3.1 expression levels in primary prostate cancer. NKX3.1 gene copy number was assessed by microsatellite analysis, fluorescence in situ hybridization, and quantitative PCR. NKX3.1 gene methylation was determined in prostate cancer cell lines and we thereby identified potential CpG methylation sites for methylation-specific PCR analysis in tissues. We validated and then applied an internally controlled fluorescence immunomicroscopic assay for NKX3.1 protein expression in 48 primary prostate cancer specimens from radical prostatectomies. NKT3.1 loss of heterozygosity was found in 27 of 43 tissues tested. Classic CpG island methylation of the NKX3.1 gene was not found in either prostate cancer cell lines or tissues. However, in 33 of 40 samples tested, CpG sites at -921, -903, and -47 were methylated to a greater degree in malignant than in adjacent normal cells. In 43 of 48 samples, NKX3.1 protein expression was reduced from 0.34 to 0.90 compared with adjacent normal luminal epithelium (mean of all samples, 0.68; 95% confidence interval, 0.05). In 12 cases that also had high-grade prostatic intraepithelial neoplasia, NKX3.1 expression levels were similar in preinvasive and invasive cancer cells and significantly lower than adjacent normal cells. Even in the presence of allelic loss, NKX3.1 expression is reduced over a wide range in prostate cancer at the time of prostatectomy, suggesting that diverse factors influence expression. Samples with protein expression below the median level in cancer cells had both NKX3.1 deletion and selective CpG methylation.