Samulin Erdem Johanna, Skaug Vidar, Bakke Per, Gulsvik Amund, Haugen Aage, Zienolddiny Shanbeh
Department of Biological and Chemical Work Environment, National Institute of Occupational Health, PO Box 8149 Dep, , N-0033, Oslo, Norway.
Department of Clinical Science, University of Bergen, Bergen, Norway.
BMC Cancer. 2016 Jan 19;16:28. doi: 10.1186/s12885-016-2061-3.
Amplifications of the transcription factor, SRY (sex determining region Y)-box 2 (SOX2), are common in non-small cell lung cancer (NSCLC). SOX2 signaling is important in maintaining the stem cell-like phenotype of cancer cells and contributes to the pathogenesis of lung cancer. TP53 is known to inhibit gene amplifications and to repress many stem cell-associated genes following DNA damage. The aim of this study was to investigate if TP53 mutational status affected SOX2 copy number variation and gene expression in early-stage NSCLC patients; moreover, to assess if TP53 regulates SOX2 expression in human lung cancer cells.
258 early-stage lung cancer patients were included in the study. Exons 4-9 in the TP53 gene were sequenced for mutations in tumor tissues. SOX2 copy number as well as TP53 and SOX2 gene expression were analyzed in tumor and in adjacent non-tumorous tissues by qPCR. TP53 and SOX2 were silenced using gene-specific siRNAs in human lung adenocarcinoma A427 cells, and the expression of TP53, SOX2 and subset of selected miRNAs was analyzed by qPCR. The odds ratios (ORs) for associations between copy number variation and lung cancer were estimated by conditional logistic regression, and the correlation between gene status and clinicopathological characteristics was assessed by Chi-square or Fisher's exact test. Gene expression data was analyzed using nonparametric Mann-Whitney test.
TP53 mutations were associated with an increased risk of acquiring a SOX2 copy number alteration (OR = 2.08, 95% CI: 1.14-3.79, p = 0.017), which was more frequently occurring in tumor tissues (34%) than in adjacent non-tumorous tissues (3%). Moreover, SOX2 and TP53 expression levels were strongly correlated in tumor tissues. In vitro studies showed that a reduction in TP53 was associated with decreased SOX2 expression in A427 cells. Furthermore, TP53 knockdown reduced the miRNA hsa-miR-145, which has previously been shown to regulate SOX2 expression.
TP53 signaling may be important in the regulation of SOX2 copy number and expression in NSCLC tumors, and the miRNA hsa-miR-145-5p may be one potential driver. This prompts for further studies on the mechanisms behind the TP53-induced regulation of SOX2 expression and the possible importance of hsa-miR-145 in lung cancer.
转录因子SRY（性别决定区Y）-盒2（SOX2）的扩增在非小细胞肺癌（NSCLC）中很常见。SOX2信号传导在维持癌细胞的干细胞样表型中起重要作用，并有助于肺癌的发病机制。已知TP53可抑制基因扩增并在DNA损伤后抑制许多与干细胞相关的基因。本研究的目的是调查TP53突变状态是否影响早期NSCLC患者的SOX2拷贝数变异和基因表达；此外，评估TP53是否调节人肺癌细胞中SOX2的表达。
本研究纳入了258例早期肺癌患者。对肿瘤组织中TP53基因的第4-9外显子进行测序以检测突变。通过qPCR分析肿瘤组织和相邻非肿瘤组织中的SOX2拷贝数以及TP53和SOX2基因表达。在人肺腺癌A427细胞中使用基因特异性siRNA使TP53和SOX2沉默，并通过qPCR分析TP53、SOX2和选定miRNA子集的表达。通过条件逻辑回归估计拷贝数变异与肺癌之间关联的优势比（OR），并通过卡方检验或Fisher精确检验评估基因状态与临床病理特征之间的相关性。使用非参数Mann-Whitney检验分析基因表达数据。
TP53突变与获得SOX2拷贝数改变的风险增加相关（OR = 2.08，95% CI：1.14-3.79，p = 0.017），其在肿瘤组织中（34%）比在相邻非肿瘤组织中（3%）更频繁出现。此外，肿瘤组织中SOX2和TP53的表达水平密切相关。体外研究表明，TP53减少与A427细胞中SOX2表达降低相关。此外，TP53敲低降低了miRNA hsa-miR-145，此前已证明该miRNA可调节SOX2表达。
TP53信号传导可能在NSCLC肿瘤中SOX2拷贝数和表达的调节中起重要作用，miRNA hsa-miR-145-5p可能是一个潜在驱动因素。这促使进一步研究TP53诱导的SOX2表达调节背后的机制以及hsa-miR-145在肺癌中的可能重要性。
