新的候选促癌基因SLC45A4调控胰腺癌恶性增殖的作用及机制研究

Pancreatic ductal adenocarcinoma (PDAC) is well-known as a universally lethal disease. However, the mechanism of its tumorigenesis and progression has not been clarified. It is beneficial to figure out the mechanism on oncogenesis and development of PDAC to improve the clinical outcome. By bioinformatics and online databases, we identified a potentially new oncogene in PDAC, solute carrier family 45 member 4 (SLC45A4). Retrospective analysis in a small amount of clinical samples implied that high expression of SLC45A4 was significantly correlated with poor prognosis of PDAC patients. Moreover, silencing of SLC45A4 attenuated proliferation and downregulation of AKT was observed. Herein, we supposed that potentially oncogenic SLC45A4 promoted tumorigenesis and progression by upregulation of AKT. In this study, we plan to detect the oncogenic function of SLC45A4 through observation of malignant behavior by gain- and loss-of-function experiment of SLC45A4; to analyze the interaction between SLC45A4 and AKT through luciferase assay, ChIP and EMSA; to evaluate the role of treating PDAC in xenograph animal model; to determine whether SLC45A4 can imply prognosis of PDAC through analyzing the relationship between SLC45A4 and clinical information in a large amount of human samples. It is believeable that this study can elucidate the oncogenic role of SLC45A4 and contribute to provide a potentially new target for diagnosis and treatment of PDAC.

胰腺癌发生发展的机制未明，阐明其发生和进展的分子机制是改善患者临床结局的有效途径。我们前期采用生物信息学方法从全球癌症基因组图谱挖掘出一个新的胰腺癌相关基因—SLC45A4，临床小样本分析显示其与预后不良相关，体内外沉默SLC45A4表达能抑制胰腺癌的恶性增殖并下调AKT，提示SLC45A4可能通过上调AKT促进胰腺癌的恶性增殖。本研究拟通过调控SLC45A4的表达，体内外观察对胰腺癌恶性生物学行为的影响；运用荧光素酶实验、染色体免疫共沉淀和EMSA等技术阐明其分子机制；建立裸鼠胰腺癌模型，在体评价靶向干预SLC45A4的治疗作用；最后应用临床大样本，分析SLC45A4与胰腺癌临床病理指标间的相关性，进一步明确其应用价值，旨在为深入阐明胰腺癌的发病机制提供新的研究思路和途径，同时亦为胰腺癌的临床诊治提供可转化应用的新靶点。

胰腺癌发生发展的机制未明，阐明其发生和进展的分子机制是改善患者临床结局的有效途径。我们前期采用生物信息学方法通过Oncomine和TCGA数据库进行胰腺癌拷贝数差异候选基因的筛选，挖掘出一个新的胰腺癌相关基因—SLC45A4。本研究拟通过CRISPR/Cas9技术构建稳定下调SLC45A4的胰腺癌稳转细胞系，体内外研究SLC45A4对胰腺癌恶性生物学行为的影响；在转录组层面，通过GSEA等生物信息学分析探讨SLC45A4促进胰腺癌恶性增殖的分子机制。利用TCGA等大型肿瘤研究数据库研究SLC45A4表达与胰腺癌临床、病理特征关系。结果显示，利用Oncomine和TCGA数据库在胰腺癌拷贝数扩增排列前1%的候选基因中，SLC45A4拷贝数扩增最明显，并与其mRNA表达呈显著正相关。此外，在多个胰腺癌组织表达芯片（GSE28735, GSE16515）中，SLC45A4呈高表达，下调SLC45A4表达后可抑制胰腺癌的增殖、侵袭和迁移。GSEA分析提示下调SLC45A4可能和胰腺癌细胞自噬削弱相关，电镜检测自噬体及Western blot检测自噬关键蛋白均得到类似结果，同时，ULK1蛋白表达下降。最后，利用Kaplan-Meier plotter数据库对SLC45A4表达在胰腺癌患者中进行生存预后分析，结果显示SLC45A4表达与胰腺癌总生存时间（Overall Survival, OS）和无病生存期（Disease-free survival, DFS）暂无明显相关性。本研究首次提出SLC45A4/ULK1/autophagy信号轴在胰腺癌恶性增殖中的作用，旨在为深入阐明胰腺癌的发病机制提供新的研究思路和途径，为SLC45A4作为胰腺癌治疗靶点提供进一步的实验依据。