GnT-V参与小细胞肺癌化疗诱导的耐药对放射抵抗性影响的机制研究

All the international cancer guidelines suggest that the radiation therapy should be performed as soon as possible after the beginning of chemotherapy for limited-stage small cell lung cancer(SCLC). However, the guides were made according to the clinical trials, without experimental data to support. Our previous studies revealed that the radiation resistance and expression of N-Acetylglucosaminyltransferases-Ⅴ(GnT-Ⅴ) were both significantly higher in SCLC patients with chemoresistance than those in chemotherapy sensitivity patients.This phenomenon was also found in the two SCLC drug resistance cells H69AR and H446AR. Besides, the radiation resistance was decreased by down-regulation of GnT-Ⅴin drug resistance cells. So, the mechanism that GnT-Ⅴ might be involved in the radiation resistance caused by chemotherapy induced drug resistance was proposed. To further study this mechanism and further analyze the network of GnT-Ⅴcontrolling radiation resistance,the following studies will be done: firstly,the changes of GnT-Ⅴexpression and radiation resistance were measured in vivo and in votro in the process of inducing drug resistance cells again; secondly, the role of GnT-Ⅴ in drug resistance, radiation resistance and prognosis of SCLC patients was explored by clinical samples;the last one, the network of GnT-Ⅴ controlling cell radiation resistance was studied by cDNA microarray and proteomic technique. The studies will provide experimental data to support the important role of early radiation therapy in limited-stage SCLC, and the way to decrease radiation resistance caused by chemotherapy induced drug resistance to improve the prognosis of SCLC patients based on GnT-Ⅴ pathway.

目前国际上局限期小细胞肺癌（SCLC）治疗指南均推荐化疗开始后应尽早放疗，但数据来源于临床，无基础实验支持。我们前期发现化疗耐药型SCLC患者和两株耐药细胞株中，N乙酰氨基葡萄糖转移酶Ⅴ(GnT-Ⅴ)的表达和放射抵抗性明显提高。下调耐药细胞中GnT-Ⅴ表达可降低其放射抵抗性。所以我们提出GnT-Ⅴ可能参与SCLC化疗诱导的耐药对放射抵抗性的影响。为进一步探讨该机制，并分析GnT-Ⅴ参与放射抵抗性调控的分子网络，本项目拟开展以下研究①化疗药重新诱导SCLC细胞，从体内外观察在诱导耐药过程中GnT-Ⅴ和放射抵抗性的改变。②利用临床标本分析GnT-Ⅴ与SCLC患者耐药、放射抵抗性和预后的关系。③基因芯片和蛋白质组学技术探讨GnT-Ⅴ参与放射抵抗性调控的分子网络。本项目将为局限期SCLC化疗开始后应尽早放疗提供基础实验数据，期望能基于GnT-Ⅴ降低化疗诱导耐药对放射抵抗性的影响，提高患者临床疗效。

放射治疗是小细胞肺癌（SCLC）患者的主要治疗方式之一，如何降低SCLC患者的放射抵抗性是临床急需解决的重要问题。本项目组前期研究发现N乙酰氨基葡萄糖转移酶Ⅴ(GnT-Ⅴ)与鼻咽癌和前列腺癌放射抵抗密切相关。因此，我们设想：GnT-Ⅴ是否参与调节SCLC放射抵抗，并对其机制进行深入探讨。.我们利用两株SCLC细胞株H1688和H146进行实验，发现：1、通过检测临床标本发现Gnt-V在小细胞肺癌组织中高表达，并且与N分期相关。2、利用干扰RNA下调H1688和H146中GnT-Ⅴ的表达后，或者过表达质粒上调GnT-Ⅴ，射线诱导的细胞凋亡率增多，细胞存活分数增加，放射抵抗性降低。3、下调或者上调GnT-Ⅴ的表达还可导致肿瘤细胞的生长受到抑制；4、细胞学和动物学实验表明降低或者提高H1688和H146中GnT-Ⅴ的表达后，上皮向间质转化（EMT）的间质标志物Zeb-2、Vimentin和N-cadherin表达降低或者升高，上皮标志物E-cadherin的表达则升高或者降低；5、下调间质标志物Zeb-2的表达后，细胞的放射抵抗性均受到抑制。以上研究结果表明：在SCLC中，高表达的GnT-Ⅴ通过诱导EMT导致肿瘤细胞放射抵抗性增加。有望通过靶向GnT-Ⅴ降低SCLC的放射抵抗性，提高患者临床疗效。.