A Role of HMGIC in Squamous Carcinoma Cells of The Oral Cavity

在之前的研究中，我们发现转录因子-高迁移率组蛋白（HMGIC/HMGA2）的表达在口腔癌中经常被观察到，并与口腔癌患者的5年生存率相关，该蛋白在发育过程中对未分化间充质细胞的分化和生长起关键作用。了解HMGIC表达的作用，将扩大对癌症进展的分子机制的认识。为此，我们开发了一种新的高通量分析方法，称为sChIP，以揭示HMGA2靶基因。我们确定了大约。100个基因，重点研究了5个不同的基因，这些基因可能与口腔癌的发展有关。RT-PCR显示，这5个基因在分化的HaCaT角质形成细胞中的表达可以忽略不计，但在未分化的HaCaT细胞中表达上调。此外，不表达HMGIC的口腔癌细胞（KOSC3, Ho1u1）与表达HMGIC基因的癌细胞（HOC313， TSU）相比，不表达这5个基因。为了了解HMGIC的转录活性，我们目前正在使用荧光素酶系统进行报告基因分析。从HMGIC -null小鼠分离的角质形成细胞中，HMGIC靶基因的表达也在研究中。我们将通过RNAi技术培养特异性敲除HMGA2基因的癌细胞系，分析HMGA2基因及其靶基因在癌细胞的致瘤性、侵袭性、转移潜能和表型改变中的直接作用。

In a previous study, we showed that expression of a transcription factor-high mobility group protein (HMGIC/HMGA2), which plays a critical role in differentiation and growth of un-differentiated mesenchymal cells during development, is frequently observed in oral carcinomas and associates with 5-year survival rate of patients suffered from the disease. Understanding a role of HMGIC expression should expand knowledge of a molecular mechanism(s) of cancer progression. In this end, we developed a novel high-throughput analysis, named sChIP, to unveil HMGA2 target genes. We identified approx. 100 genes, and focused on 5 different genes, which are expected to be involved in the progression of oral carcinomas. RT-PCR showed that expression of these 5 genes were negligible in differentiated HaCaT keratinocytes but upregulated in undifferentiated HaCaT cells. In addition, oral carcinoma cells without HMGIC expression (KOSC3, Ho1u1) did not express these 5 genes in contrast to the expression in carcinoma cells expressing HMGIC gene (HOC313, TSU). To understand the transcriptional activity of HMGIC, we are currently investigating it by a reporter assay using luciferase system. Expression of HMGIC target genes in keratinocytes isolated from Hmgic-null mice is also under investigation. We will develop carcinoma cell lines which are specifically knock-downed HMGA2 gene by RNAi, and analyze a direct role of HMGIC and the target genes on tumorgenisity, and invasiveness, metastatic potential and phenotypic alterations of carcinoma cells.