SGO-1——NSCLC通过CIN介导紫杉醇耐药的新靶点

Lung cancer is the leading cause of death in the world.Paclitaxel is the most effective cytotoxic agent currently, while its clinical use is restrained obviously because of the intrinsic drug resistace derived from tumor cells. The applicant screened the oncogenome for a new oncogene SGO-1.It has been identified being involved in the paclitaxel resistance with unidentified mechanism. Recently, it has been widely reported that the high frequency of CIN(chromosomal instability) determines the NSCLC response to pacelitaexl. Our previous study revealed that SGO-1 is highly expreseed in NSCLC docetaxel resistant cells with high frequency of CIN. On the contrary, attenuated SGO-1 expression and occurrence of CIN increased the tumor cells response to docetaxel. But the specific signal pathway and molecular mechanism has not been elucidated. This study attemptes to adopt the strategy of siRNA interferace, gene microarray, Western Blot, ChIP ,CBMN etl.to explore the mechanism of how SGO-1 mediate the intrinsic paclitaxel resistance in NSCLC by the induction of CIN.As a result, this study will provide the possibility of reversion the intrinsic pacetaxel resistance by the small molecular drug which targets particularly at SGO-1 or other genes in this signal pathway.

肺癌是目前全球死亡率最高的恶性肿瘤,化疗是这类患者的主要治疗手段。紫杉醇类药物是目前最常用的新一代药物。但在临床中，肿瘤对紫杉类药物的先天性耐药成为限制其疗效的重要原因。申请者通过癌基因筛选平台发现了一个新的癌基因SGO-1，研究证实SGO-1参与肺癌紫杉类药物耐药，但具体机制不清。近年来，染色体不稳定性（CIN）在肿瘤先天性耐药发生中的作用备受关注，CIN可决定肿瘤细胞对紫杉类药物的敏感性。我们前期研究提示：SGO-1在NSCLC紫杉耐药细胞中高表达，且诱导细胞出现CIN,抑制SGO-1的表达可逆转NSCLC的紫杉耐药，并减少CIN的发生。但其具体信号通路和分子机制尚不清楚。本课题拟采用siRNA干涉、Western Blot、染色质免疫共沉淀、CBMN等方法探讨SGO-1通过诱导CIN的发生促进NSCLC紫杉类药物先天耐药的机制,为逆转紫杉类药物先天耐药提供依据。

肺癌是目前全球死亡率最高的恶性肿瘤,化疗是这类患者的主要治疗手段。紫杉醇类药物是目前最常用的新一代药物。但在临床中，肿瘤对紫杉类药物的耐药成为限制其疗效的重要原因。申请者前期通过癌基因筛选平台发现了一个新的癌基因SGO-1，并发现其在非小细胞肺癌细胞株中高表达。为进一步研究SGO-1与肺癌细胞株对紫杉醇耐药的关系，我们首先通过反复加药诱导的方式成功构建了多西紫杉醇耐药的肺癌A549细胞株，并对其耐药特征进行鉴定。通过PCR和Western检测发现SGO-1在紫杉醇耐药肺癌细胞株中过表达。之后，我们成功构建SGO-1慢病毒载体，验证其转染效力后，成功建立SGO-1的过表达和干扰的肺癌细胞系，并通过RT-PCR和Western blot进行鉴定。干扰SGO-1的表达后，细胞的耐药特性被逆转。且抑制SGO-1的表达后耐药细胞株的凋亡增多，凋亡相关分子Bax表达增多。在实验过程中我们观察到，与亲本细胞株相比，紫衫耐药肺癌细胞株在镜下更多呈现出一种类似间质细胞的形态改变：耐药细胞株的间质相关标记表达增多，而上皮相关标记表达减少。在SGO-1过表达的肺癌细胞株中，用RT-PCR和 Western-blot及免疫荧光法检测上皮间质转化（epithelial-mesenchymal transition，EMT）分子，发现SGO-1过表达后，上皮相关的分子标记物E-cadherin、ZO-1表达减少，间质相关的分子标记物Fibronectin、Vimentin表达增多，EMT相关的转录因子ZEB-2和twist-2表达增多。因此，SGO-1很可能通过EMT的过程介导了肺癌细胞株对紫杉醇类药物的耐药。SGO-1有望成为临床上克服肺癌对紫杉醇类药物耐药的一个新靶点。