研究显示ING4在结直肠癌（CRC）中表达降低，与临床病理因素密切相关。然而ING4对CRC转移的作用及其机制仍知之甚少。课题组前期研究发现：ING4在CRC中低表达促进CRC的侵袭转移，ING4可能通过下调Snail1参与抑制CRC EMT、转移，筛选验证ING4能上调靶基因Snail1的miR-940。为此我们提出假设：ING4通过miR-940/Snail1途径下调Snail1可能是ING4抑制CRC EMT、转移的重要分子调控机制。为验证该假说，本项目将构建慢病毒介导的ING4过表达、沉默CRC细胞株，采用迁移、侵袭、Western blot、免疫组化、原位杂交、qRT-PCR、荧光素酶报告基因、miRNA激动/拮抗、siRNA、动物活体成像等方法，在细胞、动物、临床标本水平探讨ING4/miR-940/Snail1途径调控CRC EMT、转移的作用，为CRC转移的防治提供新思路。

Previous studies have shown that inhibitor of growth 4 (ING4) as an important member of inhibitor of growth protein family is reduced in human colorectal cancer (CRC), which is closely associated with clinicopathological features. However, the role of ING4 in CRC metastasis and its mechanism is still poorly understood. Our preliminary studies have demonstrated that the lower expression of ING4 in CRC promotes its invasion and metastasis. ING4 inhibits CRC metastasis very probably via reversal of epithelial-mesenchymal transition (EMT) through downregulation of Snail1 EMT-inducing transcription factor (EMT-TF). We also screened and validated that ING4 is capable of upregulating miR-940 targeting Snail1 in CRC cells. To this end, we propose the hypothesis that ING4 would downregulate Snail1 in CRC cells via the miR-940/Snail1 pathway, which may be an important regulatory mechanism for ING4-triggered suppression of EMT and metastasis in CRC. To verify the above hypothesis, we established the ING4-overexpressed and the ING4-knocked down CRC transgenic cells by using lentivirus-mediated transfection. We then examined the effect of ING4 overexpression or knockdown on CRC EMT and metastasis in in vitro cell model and in vivo tumor xenograft model in athymic BALB/c nude mouse by using the assays of wounding healing, Transwell chamber migration/invasion and in vivo bioluminescence image. We sought to elucidate the underlying mechanism, whether ING4-mediated regulation of miR-940/Snail1 signaling axis is a vital mechanism for ING4-invovled modulation the invasion and metastasis of CRC, by using the assays of Western blot, immunohistochemistry (IHC), in situ hybridization, qRT-PCR, luciferase reporter, agomir/antagomir, siRNA and so on. Furthermore, we analyzed the relationship of ING4, miR-940 and Snail1 in CRC clinical tissue specimens and then evaluated the correlation between their expression and clinicopathological characteristics or prognosis of CRC patients. This project is likely to provide the new ideas for the prevention and therapy of CRC metastasis.