miR-143/miR-145分子簇在胃癌转移中表达改变的临床意义及其功能机制研究

The prognosis of advanced GC with extensive invasion and metastasis remains poor. Owing to the mechanisms of GC metastasis are not fully understood, there is a lack of early diagnosis and effective treatment of GC metastasis. Further understanding the molecular mechanisms of metastasis and improving the prognosis are the most important and urgent issues. Recently, microRNAs (miRNAs) have been identified to play important roles in tumor metastasis. To find the metastasis-related miRNAs in GC and to clarify their roles and the underlying mechanisms in metastasis process, We screened a set of gastric cancer metastasis related miRNAs by analyzing and comparing the miRNA profiles between the primary gastric cancer and matched liver metastasis. Among them, miR-143 and miR-145 are a miRNA cluster which both located at chromosome 5. It is reported that expression of miR-143 and miR-145 are down regulated in gastric cancer tissues compared to adjacent normal tissues. In our study, we found their expressions are more significantly down regulated in the liver metastasis, suggesting their role in both the initiation of gastric cancer and progression and metastasis. Also in our previous gene profiling of 103 cases of gastric cancer tissues, a set of metastasis related genes are established. Among them, ANGPT2, FSCN1, and MAP4K4 are the predicted target genes of miR-143/miR-145, which are the regulators of angiogenesis, cytoskeleton and cancer related pathways, suggesting that miR-143/miR-145 may act via multiple targets and process. Thus, we are going to detect miR-143/miR-145 expression in gastric cancer and analyze its clinical significance, observe its biological functions in gastric cancer cells. That would help understanding the complicated process of tumor metastasis which might be modulated by miRNA, and provide some evidence for treatment of gastric cancer metastasis.

胃癌远处转移是病人死亡主要原因, 机制不明。通过miRNA芯片比较配对胃癌原发灶及其肝转移灶, 我们发现miR-143/miR-145在转移灶的表达显著下调（P<0.000）。同时对前期103例胃癌表达谱分析得到一组转移相关分子，其中ANGPT2，FSCN1，MAP4K4 是其预测靶分子。据此推测miR-143/miR-145可能通过以上靶分子分别影响肿瘤血管生成，细胞骨架及相关信号通路，从而抑制胃癌转移。本课题首先拟检测胃癌组织中miR-143/miR-145的表达，分析其临床意义。然后在细胞系中观察其生物学功能，包括增殖、凋亡、迁移、侵袭、血管生成等。从而初步证明miR-143/miR-145是新的胃癌转移抑制分子，为其治疗提供可能的新靶点。

胃癌远处转移是病人死亡主要原因, 机制不明。前期通过miRNA芯片比较11对配对胃癌原发灶及其肝转移灶, 我们发现miR-143/miR-145在转移灶的表达显著下调（P<0.000）。本项目中我们首先验证miR-143/miR-145在17例配对的胃癌原发灶及肝转移灶中的表达,进而对其在55例配对的胃癌及癌旁组织,302例胃癌组织中的表达进行Realtime PCR相对定量检测。结果显示二者在胃癌组织中的表达较癌旁正常组织下调，并在肝转移灶中进一步下调。二者在胃癌组织中的表达具有正相关性，由于二者均位于5号染色体，推测其可能作为分子簇联合表达。此外，miR-143和miR-145的表达与胃癌远处转移显著负相关。相对于miR-143和miR-145高表达的患者，二者低表达的患者生存率较低，但并未显示出统计学意义。体外实验中，通过在胃癌细胞系BGC823中分别和联合转染miR-143 mimic和miR-145 mimic, 结果显示它们能够协同抑制胃癌细胞侵袭和转移。此外，我们对103例胃癌表达谱分析得到一组转移相关分子，其中ANGPT2，FSCN1，MAP4K4 是miR-143/miR-145的预测靶分子。并观察到miR-143/miR-145的表达与ANGPT2和FSCN1呈负相关，据此推测miR-143/miR-145可能通过以上靶分子分别影响肿瘤血管生成，细胞骨架及相关信号通路，从而抑制胃癌转移。综上，我们的研究显示miRNA-143和miR-145可能作为一个联合分子簇在胃癌的转移进程中发挥抑制作用，对其下游靶基因和分子机制的研究将为胃癌转移预防和治疗提供进一步的理论依据和潜在靶点。

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