乳浆大戟提取成分通过抑制P-糖蛋白和促进凋亡而拮抗人胃癌细胞多药耐药的研究

Chemotherapy is the main treatment for advanced gastric cancers and postsurgical gastric cancers, but gastric cancers form multi-drug resistance (MDR) that makes the therapy less effective. P-glycoprotein up-regulation and apoptosis inhibition are two important mechanisms of MDR. Previous studies have found that Euphorbia esula can induce apoptosis of human gastric cancer cells and can improve the sensitivity of MDR gastric cancer cells to chemotherapeutic drugs. 3 kinds of flavonoids and 3 kinds of diterpenoids have been extracted from Euphorbia esula. It was reported that flavonoids had the effect of inhibiting P-glycoprotein and diterpenoids had the effect of inducing apoptosis. So we reasoned that the flavonoids in Euphorbia esula can inhibit P-glycoprotein and the diterpenoids in Euphorbia esula can promote apoptosis, thus antagonizing gastric cancer multidrug resistance. To verify the reasoning, we employ RT-PCR and Western Blot to detect respectively the expressions of P-glycoprotein mRNA and protein in MDR gastric cancer cells treated with the flavonoids in Euphorbia esula, employ rhodamine accumulation and enzyme activity measurement to analyze the influence of the flavonoids on the function of P-glycoprotein in MDR gastric cancer cells, and employ real-time fluorescent quantitative PCR to study the signaling pathways that regulate the expression of P-glycoprotein. The induction of apoptosis of MDR gastric cancer cells by the diterpenoids in Euphorbia esula will be studied by confocal microscopy, electron microscopy, and flow cytometry; the mechanisms and pathways of MDR gastric cancer cell apoptosis will be studied by a variety of methods.

化疗是进展期胃癌和胃癌术后的主要治疗手段，但胃癌产生多药耐药(MDR)使疗效不佳。P-糖蛋白上调和凋亡受抑是MDR的两个重要机制。前期研究发现，乳浆大戟能诱导人胃癌细胞凋亡，可提高MDR胃癌对化疗药的敏感性。从乳浆大戟提取到3种黄酮类和3种二萜类化合物；有报道称黄酮类有抑制P-糖蛋白、二萜类有诱导凋亡的作用。于是我们推理，乳浆大戟的黄酮类能通过抑制P-糖蛋白、二萜类能通过促进凋亡而拮抗胃癌多药耐药。为验证该推理，拟用RT-PCR和Western Blot检测乳浆大戟黄酮类作用MDR胃癌细胞后P-糖蛋白mRNA和蛋白的表达，用罗丹明累积和酶活性测定分析其对MDR胃癌细胞P-糖蛋白功能的影响，用实时荧光定量PCR等研究其调节P-糖蛋白表达的信号通路。用共聚焦显微镜、电子显微镜、流式细胞仪等研究乳浆大戟二萜类诱导MDR胃癌细胞发生凋亡的作用，并用多种方法研究其诱导MDR胃癌细胞凋亡的机制和通路。

化疗是进展期胃癌和胃癌术后的主要治疗手段，但由于胃癌细胞产生多药耐药（multidrug resistance, MDR）而使疗效不佳。P-糖蛋白表达上调和细胞凋亡受抑制是MDR的两个重要机制。本项目研究发现，乳浆大戟提取成分能够增加人胃癌多药耐药细胞SGC7901/ADR对化疗药物阿霉素和紫杉醇的敏感性；乳浆大戟提取成分能通过抑制P-糖蛋白表达与活性和诱导细胞凋亡而拮抗或逆转人胃癌细胞的多药耐药；乳浆大戟提取成分能够抑制人胃癌多药耐药SGC7901/ADR细胞的增殖、抑制细胞迁移和侵袭，并使细胞周期阻滞；乳浆大戟诱导细胞凋亡的作用有死亡受体通路和线粒体通路的参与。乳浆大戟提取成分若进一步能得到开发与利用，对多药耐药胃癌的辅助治疗有一定的实际意义。