多药耐药（mdr）是胃癌患者化疗失败的关键原因,热疗在逆转胃癌mdr的过程中起重要作用。研究表明，hedgehog（hh）/smo信号通路的激活或cyclind1蛋白的高表达均可引起肿瘤细胞的mdr，但二者在胃癌mdr中的作用机制尚不清楚。申请者前期研究表明高精度腹腔热灌注化疗(hhipc)可上调mir-218的表达并通过抑制mdr相关基因的表达来增强胃癌化疗的敏感性。因此，我们提出"高精度腹腔热灌注化疗上调mir-218并通过抑制hh/smo信号通路和/或cyclind1的表达来逆转胃癌mdr"这一科学假说。本课题拟设计下列内容：①hhipc上调mir-218能有效逆转胃癌mdr；②阐明hh/smo信号通路和cyclind1在其中的分子机制，并对上述结果进行临床验证。本项目将为确立mir-218在hhipc中作为抑制胃癌mdr的新靶点提供科学依据。

multidrug resistance (mdr) in gastric cancer remains a major challenge to chemotherapy treatment.thermal therapy plays an important role in the reversal of mdr.studies have also shown that the activation of hh/smo signal pathway or the overexpression of cyclind1 protein can lead to the mdr of tumors. but until now, the mechanisms of hh/smo and cyclind1 are unclear in gastric cancer. applicant's earlier studies showed that high-precision hyperthermic intraperitoneal chemotherapy (hhipc)could upregulate the expression of mir-218 and inhibit the expression of mdr-related genes to enhance the sensitivity of chemotherapy in gastric cancer. so, we propose that hhipc can upregulate the expression of mir-218 and inhibit hh/smo signal pathway or the expression of cyclind1 and reverse the mdr of gastric cancer. therefore, we designed the research project as follows:first,hhipc can reverse the mdr of gastric cancer effectively; second,to clarify the detailed mechanism of hh/smo signal pathway and the expression of cyclind1 during the process of hhipc. this project will establish the new target of mir-218 in high-precision hyperthermic intraperitoneal chemotherapy and provide the scientific basis for it.

多药耐药（mdr）是导致胃癌化疗失败的重要原因。前期我们对5例胃癌患者经腹腔热灌注化疗（hipec）前后的血清采用mirna表达谱筛选，发现mir-218在hipec后胃癌患者血清中的表达明显上调且高达8倍以上，同时mir-218还是胃癌mdr的候选分子，进一步分析发现hipec后mdr相关基因的表达显著下降，这一现象提示mir-218可能具有增强胃癌化疗疗效甚至逆转胃癌mdr的作用。为了明确mir-218在胃癌及其胃癌化疗耐药中发挥的作用及其机制，首先我们检测了mir-218在胃癌及相应癌旁组织中的表达，发现其在胃癌组织中低表达且与胃癌进展相关，在胃癌细胞株中过表达mir-218可以显著抑制胃癌细胞增殖、集落形成及裸鼠皮下成瘤能力，我们还发现mir-218通过靶向mtor更增强了胃癌细胞对化疗药物的敏感性。接着我们通过rt-pcr检测发现mir-218在胃癌耐药细胞株中低表达及mdr相关基因高表达，在胃癌耐药细胞株中过表达mir-218可以显著提高耐药的胃癌细胞对化疗药的敏感性，并且显著促进了化疗药诱导的胃癌耐药细胞凋亡。为了阐明mir-218在胃癌中发挥的抑癌作用及逆转胃癌mdr的分子机制，我们经网站预测可见mir-218靶向smo、cyclind1 及gli2，且荧光素酶报告基因试验证实了smo、cyclind1 及gli2是mir-218的下游靶基因，上调mir-218表达可以明显抑制smo、cyclind1 和gli2的表达，且抑制mdr相关基因mdr-1和p-gp、抗凋亡基因bcl-2的表达及增强了促凋亡基因bax、cleaved caspase-3和转移相关基因e-cadherin的表达，进而发挥了mir-218逆转胃癌细胞mdr及抑制胃癌细胞增殖和侵袭，促进胃癌细胞凋亡的作用。我们研究发现热化疗可以上调mir-218的表达，抑制下游基因bcl2和gli2的表达和促进bax、cleaved caspase-3和e-cadherin的表达，进而抑制胃癌细胞增殖、侵袭及增强胃癌细胞对顺铂的化疗敏感性。本项目探索了mir-218对胃癌mdr的影响及生物学机制，为以hipec后上调的mir-218为研究靶向，克服胃癌细胞的mdr、提高胃癌化疗效果提供理论基础和临床依据。