同源异型盒1 (sine oculis homeobox homolog 1,SIX1)基因参与多种肿瘤调控,在乳腺癌发生发展过程中发挥了重要作用,但具体机制仍有待探讨.本研究目的 在于分析SIX1基因在乳腺癌中的表达情况,研究其在乳腺癌细胞增殖与侵袭过程中所发挥的作用并探讨作用的机制.TCGA数据库和GEPIA2在线数据库分析发现,SIX1在乳腺癌中的表达高于正常组织,且在乳腺癌的不同分子亚型Basal-like、HER2、Luminal A、Luminal B中也证实了这一点(P＜0.05);HPA数据库分析发现,SIX1的免疫组化蛋白质表达水平高于正常乳腺组织,SIX1基因在乳腺癌中高表达,差异具有统计学意义(P＜0.001).在乳腺癌细胞株MDA-MB-231中,干扰SIX1的表达及在MCF-7中过表达SIX1后,生长曲线及EdU实验结果显示:敲低SIX1后乳腺癌细胞的生长增殖受到抑制,而过表达SIX1则会发挥促进作用(生长曲线实验:P＜0.05;EdU实验:P＜0.001);Transwell结果表明,SIX1能够增强乳腺癌细胞的侵袭能力(P＜0.001).利用TCGA数据库,根据SIX1基因表达值的上下四分位定义SIX1基因高表达及低表达人群,对两组队列进行差异基因分析,发现差异基因与代谢、干细胞调控等通路相关;对敲低SIX1的乳腺癌细胞系进行转录物组测序(RNA-sequencing,RNA-seq),并对测序结果进行一系列生物信息学分析发现,SIX1与代谢、干细胞调控以及EMT等通路密切相关.挑选代表性基因MYC、SNAI2、EGFR,通过已发表的GEO临床数据集以及KM-plot-ter验证靶基因与SIX1表达的相关性及与临床乳腺癌病人的预后关系,我们发现:SIX1与MYC、SNAI2、EGFR表达正相关.高表达的SIX1、MYC、SNAI2与EGFR不利于乳腺癌病人的生存.利用GCBI、GeneMANIA及String在线工具,我们发现了SIX1基因相互作用的蛋白质和相关的lncRNA及miRNA.综上,本研究中初步揭示了SIX1在乳腺癌中发挥的作用及其调控机制,为进一步深入研究该基因提供了线索.

Pancreatic cancer is a common malignant tumor with poor prognosis. Recently, cancer stem cells (CSCs) were identified in several solid tumors, including pancreatic cancer. Although accumulating evidence indicates that sirtuin 1 (SIRT1) exerts biological functions in various cancers, how it contributes to tumorigenesis and metastasis of pancreatic cancer, as well as its role in CSCs, is still poorly defined. Here we show that SIRT1 interacts with the Cullin 4B (CUL4B)-Ring E3 ligase (CRL4B) complex, which is responsible for H2AK119 monoubiquitination (H2AK119ub1), collaborating as a functional unit. Genome-wide analysis of SIRT1/CUL4B targets identified a cohort of genes, including GRHL3 and FOXO3, critically involved in cell differentiation, growth, and migration. Furthermore, we found that SIRT1 and CUL4B collectively promote the proliferation, autophagy, and invasion of pancreatic cancer cells. Remarkably, we demonstrate that SIRT1/CUL4B promotes CSC-like properties, including increased stemness marker expression and sphere formation. In vivo experiments implied that SIRT1 promoted established tumor xenograft growth, increased tumor-initiating capacity in NOD/SCID mice, and increased CSC frequency. Strikingly, SIRT1 and CUL4B expression is markedly upregulated in a variety of human cancers, including pancreatic cancer. Our data provide a molecular basis for the functional interplay between histone deacetylation and ubiquitination. The results also implicate the SIRT1/CRL4B complex in pancreatic cancer metastasis and stem cell properties, thus supporting SIRT1 as a promising potential target for cancer therapy development.

Background: Triple-negative breast cancer (TNBC) is a high-risk breast cancer subtype, which accounts for 15% to 20% of all breast cancers and generally has a poor prognosis. TNBC patients have high recurrence post-surgery and high risk of metastasis to other organs. The tumor microenvironment (TME) plays important roles in the carcinogenesis, development, and metastasis of tumors. Methods: This study aimed to investigate the effects of immune and stromal cell-related genes on TNBC prognosis. The ESTIMATE algorithm was used to calculate the immune/stromal scores of TNBC samples from the GEO database. The samples were divided into high- and low- score groups and the differential expression genes were identified using the limma package within R. Functional enrichment and protein-protein interaction (PPI) network analyses revealed that these genes are primarily involved in immune responses. Results: Survival analysis in both GSE21653 and KM-plotter website showed that 36 genes were significantly related to disease-free survival (DFS) of TNBC. Another survival analysis by R package survival in GSE58812 indicated that 14 genes of 36 were greatly interrelated to DFS of TNBC. Moreover, the expression levels of some of these genes were verified through immunohistochemical staining and RT-qPCR. Finally, four genes importantly associated with TNBC prognosis were identified with Cox-LASSO analysis. Time-dependent receiver-operating characteristic (ROC) analysis displayed an area under the curve (AUC) of 0.95 for one-year survival rate, indicating the four genes performed very well for prognosis prediction. Conclusions: In conclusion, we identified four genes, including BIRC3, CD8A, GNLY and TRIM22, that are possibly associated with the TME and are potential prognostic and therapeutic markers of TNBC.