SNP55, a new functional polymorphism of MDM2-P2 promoter, contributes to allele-specific expression of MDM2 in endometrial cancers.
SNP55, a new functional polymorphism of MDM2-P2 promoter, contributes to allele-specific expression of MDM2 in endometrial cancers.
复制标题
SNP55是MDM2-P2启动子的一种新的功能多态性，在子宫内膜癌中有助于MDM2的等位基因特异性表达。
DOI：
10.1186/s12881-015-0216-8
复制
发表时间：
2015-08-21
影响因子：
--
通讯作者：
Kato K
中科院分区：
文献类型：
--
作者：
Okamoto K;Tsunematsu R;Tahira T;Sonoda K;Asanoma K;Yagi H;Yoneda T;Hayashi K;Wake N;Kato K
已知 MDM2 启动子区域中的功能性单核苷酸多态性 (SNP) SNP309 与多种疾病，特别是癌症相关。尽管已经进行了许多研究来证明 SNP309 上等位基因特异性表达 (ASE) 的机制，但它们仅利用体外技术。目前尚不清楚 MDM2 的 ASE 在体内是否仅归因于 SNP309。我们尝试在单链构象多态性条件下使用后标记和自动毛细管电泳来评估 MDM2 体内的 ASE。为了测量定量差异，我们利用 MDM2 外显子上的 SNP 作为标记，其在大群体中处于杂合状态。为了解决 ASE 超过 20% 的原因，我们确认了 MDM2-3'UTR 和启动子区域的序列。我们使用生物分子相互作用分析和荧光素酶测定评估了可能是 ASE 原因的 SNP。仅当使用 SNP rs1690916 作为标记时，在子宫内膜癌中检测到超过 20% 的 ASE，但在无癌子宫内膜样本中检测不到。我们怀疑子宫内膜癌中的这种ASE是由MDM2-P2启动子中的序列异质性引起的，并发现了一个新的功能多态性，我们将其标记为SNP55。无癌子宫内膜和子宫内膜癌样本之间的 SNP55 基因型频率和等位基因频率都没有差异，因此，SNP55 单独不会影响子宫内膜癌风险。 SNP55 状态影响转录因子 Sp1 和核因子 kappa-B (NFκB) 的 DNA 结合亲和力。含有 SNP55C 的 P2 启动子的转录活性被 NFκB p50 同二聚体抑制，但 SNP55T 的转录活性则不然。仅 ASE 阳性子宫内膜癌样本显示 NFκB p50 的核定位。我们的研究结果表明，SNP55 状态和 NFκB p50 活性在子宫内膜癌中 MDM2 的转录调控中都很重要。
The functional single nucleotide polymorphism (SNP) in the MDM2 promoter region, SNP309, is known to be associated with various diseases, particularly cancer. Although many studies have been performed to demonstrate the mechanism of allele-specific expression (ASE) on SNP309, they have only utilized in vitro techniques. It is unknown whether ASE of MDM2 is ascribed solely to SNP309, in vivo. We attempted to evaluate ASE of MDM2 in vivo using post-labeling followed by automated capillary electrophoresis under single-strand conformation polymorphism conditions. For measuring a quantitative difference, we utilized the SNPs on the exons of MDM2 as markers, the status of which was heterozygous in a large population. To address the cause of ASE beyond 20 %, we confirmed sequences of both MDM2-3’UTR and promoter regions. We assessed the SNP which might be the cause of ASE using biomolecular interaction analysis and luciferase assay. ASE beyond 20 % was detected in endometrial cancers, but not in cancer-free endometria samples only when an SNP rs1690916 was used as a marker. We suspected that this ASE in endometrial cancer was caused by the sequence heterogeneity in the MDM2-P2 promoter, and found a new functional polymorphism, which we labelled SNP55. There was no difference between cancer-free endometria and endometrial cancer samples neither for SNP55 genotype frequencies nor allele frequencies, and so, SNP55 alone does not affect endometrial cancer risk. The SNP55 status affected the DNA binding affinity of transcription factor Sp1 and nuclear factor kappa-B (NFκB). Transcriptional activity of the P2 promoter containing SNP55C was suppressed by NFκB p50 homodimers, but that of SNP55T was not. Only ASE-positive endometrial cancer samples displayed nuclear localization of NFκB p50. Our findings suggest that both the SNP55 status and the NFκB p50 activity are important in the transcriptional regulation of MDM2 in endometrial cancers.