YB-1, the E2F Pathway, and Regulation of Tumor Cell Growth
YB-1, the E2F Pathway, and Regulation of Tumor Cell Growth
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DOI：
10.1093/jnci/djr512
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发表时间：
2012-01-01
影响因子：
10.3
通讯作者：
Braithwaite, Antony W.
中科院分区：
文献类型：
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作者：
Lasham, Annette;Samuel, Weini;Braithwaite, Antony W.
背景Y-box结合因子-1(YB-1)与多种肿瘤的预后有关。YB-1基因表达下调可抑制肿瘤细胞生长，但其机制尚不清楚。方法采用基因芯片技术比较771例乳腺癌患者的YB-1基因表达水平与肿瘤分级和组织学的关系，以及375例未接受辅助治疗的乳腺癌患者的无瘤生存期和无远处转移生存期。微阵列进一步搜索与YB-1mRNA表达相关的基因。应用小干扰RNA(SiRNA)技术研究YB-1基因表达下调对三种肿瘤细胞系(MCF-7乳腺癌细胞、HCT116结肠癌细胞和A549肺癌细胞)生长的影响、对A549细胞裸鼠致瘤性的影响以及对三种肿瘤细胞系整体转录的影响。报告基因检测YB-1 siRNAs是否影响E2F1的表达，染色质免疫沉淀法检测YB-1是否与不同的E2F启动子以及E2F1调控的启动子结合。结果YB-1水平在侵袭性较强的肿瘤中升高，与无瘤生存期和无远处转移生存期密切相关。YB-1的表达往往与其启动子中含有E2F位点的基因的表达有关。表达YB-1 siRNA的细胞生长速度明显慢于对照细胞，并且在裸鼠体内不太容易形成肿瘤。在带有YB-1 siRNA的癌细胞系中改变的转录本包括32个基因，这些基因是预后基因表达特征的组成部分。YB-1可调控E2F1启动子-报告基因在A549细胞中的表达(例如，E2F1启动子的相对活性，对照siRNA=4.04；YB-1 siRNA=1.40，差异=-2.64，95%可信区间=-3.57~-1.71，P<；.001)，并与几个明确的E2F1靶基因启动子结合。结论YB-1的表达与E2F转录因子的活性有关，可能通过这种机制控制肿瘤细胞的生长。
Background Y-box binding factor 1 (YB-1) has been associated with prognosis in many tumor types. Reduced YB-1 expression inhibits tumor cell growth, but the mechanism is unclear.Methods YB-1 mRNA levels were compared with tumor grade and histology using microarray data from 771 breast cancer patients and with disease-free survival and distant metastasis-free survival using data from 375 of those patients who did not receive adjuvant therapy. Microarrays were further searched for genes that had correlated expression with YB-1 mRNA. Small interfering RNA (siRNA) was used to study the effects of reduced YB-1 expression on growth of three tumor cell lines (MCF-7 breast, HCT116 colon, and A549 lung cancer cells), on tumorigenesis by A549 cells in nude mice, and on global transcription in the three cancer cell lines. Reporter gene assays were used to determine whether YB-1 siRNAs affected the expression of E2F1, and chromatin immunoprecipitation was used to determine whether YB-1 bound to various E2F promoters as well as E2F1-regulated promoters. All P values were from two-sided tests.Results YB-1 levels were elevated in more aggressive tumors and were strongly associated with poor disease-free survival and distant metastasis-free survival. YB-1 expression was often associated with the expression of genes with E2F sites in their promoters. Cells expressing YB-1 siRNA grew substantially more slowly than control cells and formed tumors less readily in nude mice. Transcripts that were altered in cancer cell lines with YB-1 siRNA included 32 genes that are components of prognostic gene expression signatures. YB-1 regulated expression of an E2F1 promoter-reporter construct in A549 cells (eg, relative E2F1 promoter activity with control siRNA = 4.04; with YB-1 siRNA = 1.40, difference= -2.64, 95% confidence interval = -3.57 to -1.71, P < .001) and bound to the promoters of several well-defined E2F1 target genes.Conclusion YB-1 expression is associated with the activity of E2F transcription factors and may control tumor cell growth by this mechanism.