Methylation-associated silencing of S100A4 expression in human epidermal cancers
Methylation-associated silencing of S100A4 expression in human epidermal cancers
复制标题
人类表皮癌中 S100A4 表达的甲基化相关沉默
DOI：
10.1111/j.1600-0625.2009.00922.x
复制
发表时间：
2009-10-01
影响因子：
3.6
通讯作者：
Li, Hong
中科院分区：
文献类型：
--
作者：
Li, Yan;Liu, Zhi-Li;Li, Hong
S100A4似乎对癌症转移很重要，其过表达在多种人类恶性肿瘤中很常见，但其在表皮癌中的地位仍鲜为人知。同样，E-cadherin下调和Wnt激活是常见的癌症相关改变，而它们与皮肤病变中S100A4表达的潜在相关性尚未被表征。本研究利用组织微阵列免疫组化染色、逆转录酶聚合酶链反应和western blotting技术解决了这些问题。同时阐明了表皮肿瘤中S100A4表达改变的潜在表观遗传机制。免疫组化结果显示，S100A4在正常表皮中表达频率为100%(8/8)，在肿瘤周围非癌表皮中表达频率为80.6%(25/31)，在癌前病变中表达频率为66.7%(10/15)，在Bowen病中表达频率为8.3%(1/11)，在不同癌组织中表达频率为7.7-26.3%。S100A4在正常和非癌表皮中的检出率与表皮癌的检出率差异有统计学意义（P = 0.000）。因此，人永活角质形成细胞系HaCat表达S100A4阳性，而皮肤鳞状细胞癌（SCC）细胞系col16表达S100A4阳性。S100A4下调、E-cadherin减少和Wnt激活在大多数表皮癌中共存，但不必要地重叠。甲基化DNA测序显示，在S100A4阴性的col16细胞和皮肤SCCs中，S100A4内含子中四个关键位点（胞嘧啶和鸟嘌呤被磷酸或- c -磷酸- g -分离）首先甲基化，去甲基化/5-aza-2'-脱氧胞苷处理有效地恢复了S100A4在col16细胞中的表达。我们的研究结果表明，S100A4下调作为DNA甲基化的结果，与皮肤肿瘤的形成密切相关。Wnt激活与E-cadherin减少和S100A4下调是皮肤肿瘤中平行的分子事件，可能作为预测表皮癌风险的生物标志物。
S100A4 appears important for cancer metastasis and its overexpression is common in a variety of human malignancies, but its status in epidermal cancers remains lesser known. Likewise, E-cadherin downregulation and Wingless (Wnt) activation are frequent cancer-associated alterations, whereas their potential correlations with S100A4 expression in skin lesions have not been characterized. These issues were addressed in the present study using tissue microarray-based immunohistochemical staining, reverse transcriptase polymerase chain reaction and western blotting. Meanwhile, the underlying epigenetic mechanism leading to the altered S100A4 expression in epidermal tumors was elucidated. Immunohistochemistry revealed that S100A4 expression frequencies were 100% (8/8) in normal epidermis, 80.6% (25/31) in tumor-surrounding non-cancerous epidermis, 66.7% (10/15) in premalignant diseases, 8.3% (1/11) in Bowen's disease and 7.7-26.3% in different cancer tissues. The incidence of S100A4 detection in the normal and non-cancerous epidermis was significantly different from that of epidermal cancers (P = 0.000). Accordingly, human immortalized keratinocyte line HaCat but not skin squamous cell carcinoma (SCC) line colo16 was positive in S100A4 expression. S100A4 downregulation, E-cadherin reduction and Wnt activation coexisted in most of epidermal cancers but unnecessarily overlapped. Methylation DNA sequencing revealed methylation of four critical (cytosine and guanine separated by a phosphate or -C-phosphate-G-) CpG sites within S100A4 intron first in S100A4-negative colo16 cells and skin SCCs, and demethylator/5-aza-2'-deoxycytidine treatment efficiently recovered S100A4 expression in colo16 cells. Our findings demonstrate that S100A4 downregulation, as the consequence of DNA methylation, is closely correlated with skin tumor formation. Wnt activation and E-cadherin reduction and S100A4 down-regulation are paralleled molecular events in skin tumors, which may serve as the biomarkers for predicting epidermal cancer risk.