胃癌干细胞靶向性Gli1 siRNA纳米粒对胃癌复发转移的干预作用研究

Gastric cancer stem cells play an important role in the initiation, development, relapse and metastasis of gastric cancer. How to eliminate the remained cancer stem cells during the chemotherapy is still a scientific problem to be solved. Cancer stem cells have emerged as the new targets for anti-cancer therapy. The CD44 has recently been considered as a gastric cancer stem cells surface marker. In order to eliminate gastric cancer stem cells, we developed a novel gastric cancer stem cells-specifically targeting Gli1 siRNA nanoparticles. A distearoylphosphatidylethanolamine-hyaluronic acid conjugate (DSPE-HA) with a single coupling point was synthesized as the targeting molecule, siRNA targeting Gli1 was selected as the model drug, and gastric cancer stem cells targeting Gli1 siRNA nanoparticles were developed by modifying DSPE-HA on the surface of nanoparticles. The CD44 receptor mediated DSPE-HA modified Gli1 siRNA nanoparticles can increase the the intracellular uptake of Gli1 siRNA by gastric cancer stem cells. The gastric cancer stem cells targeting Gli1 siRNA nanoparticles are to be used for blocking the Hedgehog signaling pathway of self-renew, proliferation and differentiation of cancer stem cells, suppressing the invasion and metastasis of cancer stem cells， inducing cancer stem cells apoptosis，thus providing a new strategy for treating gastric cancer stem cells and preventing its recurrence and metastasis.

胃癌干细胞在胃癌的发生、发展、复发和转移中起着决定性作用。如何在治疗的同时根除胃癌干细胞防止胃癌的复发和转移是仍待解决的重要科学问题。本项目针对胃癌干细胞的表面标志CD44为靶点，选择靶向Gli1基因的siRNA为模型药物，合成的二硬脂酰磷脂酰乙醇胺－透明质酸（DSPE-HA）为靶向修饰材料，以自组装的方法构建一种以预防胃癌复发和转移为目的的新型胃癌干细胞靶向性Gli1 siRNA纳米粒。通过主动靶向到胃癌干细胞，阻断胃癌干细胞自我增殖分化的Hedgehog信号转导通路、抑制胃癌干细胞的侵袭与转移、诱导胃癌干细胞凋亡，并从分子、细胞、动物水平阐明其根除胃癌干细胞的作用机制，评价其预防胃癌干细胞导致的胃癌复发和转移的治疗效果。本项目对于临床上广泛存在的迫切待解决的胃癌复发、转移等重大科学问题，提供了新的理论与实验基础。

胃癌干细胞在胃癌的发生、发展、复发和转移中发挥着重要作用。胃癌干细胞对常规的化疗药物表现出较强的耐药性、对放射治疗表现出耐受性，治疗后少量残存的胃癌干细胞是胃癌复发和转移的根源。因此，胃癌干细胞的根除是胃癌治疗的主要目的。本项目针对胃癌干细胞的|表面标志CD44为靶点，，选择靶向Gli1基因的siRNA为模型药物，合成的二硬脂酰磷脂酰乙醇胺－透明质酸（DSPE-HA）为靶向修饰材料，以自组装的方法构建一种以预防胃癌复发和转移为目的的新型胃癌干细胞靶向性Gli1 siRNA纳米粒。从人源胃癌AGS细胞中分选出的胃癌干细胞表型为CD 44+细胞亚群，在添加生长因子的无血清培养基中进行悬浮培养。本项目的靶向性Gli1 siRNA纳米粒能明显抑制胃癌干细胞的自我更新能力、悬浮细胞球形成能力和软琼脂集落形成能力，阻断胃癌干细胞的侵袭与转移。构建的靶向性Gli1 siRNA纳米粒可以促进胃癌干细胞对Gli1 siRNA的摄取，沉默Gli1基因的表达，阻断Hedgehog 信号通路，显著抑制胃癌干细胞的增殖，诱导胃癌干细胞凋亡。靶向性Gli1 siRNA纳米粒增加了Gi1 siRNA在肿瘤部位的蓄积，可以有效抑制胃癌干细胞移植瘤的增长，显示出很高的抗肿瘤活性。总之，靶向性Gli1 siRNA纳米粒将为胃癌干细胞的选择性靶向和有效清除提供一种新型的策略，可望从根本上阻止胃癌干细胞导致的胃癌复发和转移。