癌高甲基化基因 1 调控前列腺癌上皮-间质转化的作用及机制

In recent years, the incidence of prostate cancer is constantly increasing in our country.Invasion and metastasis are primary cause of the death of prostate cancer patient. However, until now the knowledge of the molecular mechanism of its invasion and metastasis is very limited. Our previous results showed that HIC1 modulates prostate cancer progression and metastasis by DNA methylation of epigenetic modification. Hypermethylated in cancer 1(HIC1) are low expression both human prostate cancer cells and cancer tissues and closly correlated with the invasion and metastasis of prostate cancer. Furthermore, overexpression of HIC1, some markers during epithelium-mesenchymal transition(EMT) and transcription factor snail in prostate cancer cells are more markedly changed. But there are few reports about this phenomenon and its molecular machanism.We speculated that HIC1 maybe binds with some transcription factors and induces prostate cancer to occur EMT. Thus, we have established prostate cancer cells proposed EMT model and constucted prostate cancer model of mice by conditional knock out Pten and Hic1 supressors in mice prostate epithelia. On one hand，we are going to further carry out microarray, reporter gene and chromatin immunoprecipitation assays and so on in vitro and in vivo to explore the molecular machanism of HIC1 regulating EMT in prostate cancer. On the other hand, we are interested in investigating whether cancer-associated fibroblasts(CAFs) in prostate cancer microenviroment contribute to modulating HIC1 expression in tumor cells by secretion of many cytokines,regulating EMT in prostate cancer. In summary, these results maybe help us to clarify the molecular machanism of the invasion and metastases of prostate cancer and provide some evidences of diagnosis and treatment for prostate cancer.

近年来我国前列腺癌的发病率不断攀升，侵袭、转移是患者死亡的主要原因，但是机制不清楚。我们前期研究发现癌高甲基化基因1（HIC1）因甲基化修饰导致在前列腺癌细胞和组织中低表达，与前列腺癌侵袭、转移有关；过表达HIC1后，前列腺癌细胞中上皮-间质转化（EMT）标志物和转录因子Snail等的表达明显改变,HIC1可能参与调控EMT影响前列腺癌侵袭、转移，但是目前鲜见报道。我们推测HIC1在肿瘤微环境中结合某些转录因子，诱导前列腺癌发生EMT。据此拟在已建立的前列腺癌EMT细胞模型株和Pten、Hic1基因敲除小鼠模型中，采用基因芯片、报告基因和染色质免疫共沉淀等实验，体内外深入解析HIC1调控前列腺癌发生EMT的分子机制；探讨在微环境中基质成纤维细胞通过表观遗传修饰调节HIC1表达，调控前列腺癌发生EMT。本研究有助于阐明前列腺癌侵袭、转移的作用机制，为前列腺癌的诊治提供科学依据。

近年来，随着国民平均寿命的延长、生活方式与饮食结构的改变，中国前列腺癌的增长极为明显。据报道，上皮细胞间质转化是前列腺癌发生远处转移的始动环节，但其调控机制尚未完全阐明。癌高甲基化基因1(HIC1)是一个抑癌基因，因表观遗传甲基化修饰导致其在多种癌细胞和组织中表达沉默，可能与肿瘤的发生、发展有关。本研究对前列腺癌细胞株PC3HIC1和C4-2BHIC1进行全基因组芯片分析，实时荧光定量PCR分析和Western blot分析发现HIC1过表达人前列腺癌细胞系中CXCR7和Snail基因水平表达量下调，E-Cadherin基因水平表达量上调，Vimentin蛋白质表达下调，前列腺癌细胞发生了EMT的抑制现象。同时在HIC1过表达前列腺癌细胞PC3和C4-2B中，Akt 的活性形式p-Akt (Ser473)蛋白表达水平下降，Snail表达下调；而Akt 活性形式p-Akt (Thr308)表达无变化，意味着HIC1可能通过改变p-Akt信号通路蛋白和Snail蛋白的表达来抑制EMT，降低前列腺癌细胞PC3和C4-2B的生长和侵袭转移功能；而且经免疫组织学染色，发现过表达HIC1前列腺癌细胞PC3HIC1组小鼠肿瘤组织与PC3GFP细胞组小鼠肿瘤组织比较，E-Cadherin、Vimentin的蛋白质表达均存在明显差异，变化趋势与细胞株内结果相似，进一步由体内实验证明HIC1可能抑制EMT的发生，从而降低前列腺癌的形成和侵袭转移功能。此外，在分析前列腺癌EMT相关差异基因的过程中，我们利用前列腺穿刺组织进行了基因芯片实验，qRT-PCR验证发现了四个基因ITGBL1，HOXA7，KRT15，TGM4，进一步研究相关差异基因可以了解前列腺癌发生远处转移的机制并为建立个体化治疗方案和预后评估系统提供帮助。