Department of Neurosurgery, Sheba Medical Center, Ramat Gan; Affiliated with the Sackler School of Medicine, Tel Aviv, Israel.
Cancer Research Center, Sheba Medical Center, Ramat Gan; Affiliated with the Sackler School of Medicine, Tel Aviv, Israel.
World Neurosurg. 2019 Oct;130:e324-e332. doi: 10.1016/j.wneu.2019.06.082. Epub 2019 Jun 20.
Klotho, a single-pass transmembrane protein associated with premature aging, acts as a tumor suppressor gene by inhibiting insulin/insulin-like growth factor-1 and fibroblast growth factor pathways. Downregulated Klotho expression is reported in melanoma, mesothelioma, bladder, breast, gastric, cervix, lung, and kidney cancers and is associated with a poor prognosis. Klotho expression and Klotho promoter hypermethylation are predictive factors for patient prognosis.
To investigate the potential role of Klotho in glioblastoma-multiforme (GBM), 22 GBM samples were collected from the Sheba Tumor Bank and examined.
We found that increased Klotho messenger ribonucleic acid (RNA) expression predicted longer survival (P = 0.03) of GBM patients. Methylation analysis was performed on bisulfite-treated deoxyribonucleic acid from the GBM patient samples using ionization time-of-flight mass spectrometry according to the Sequenom EpiTYPER protocols. Klotho promoter hypermethylation was detected in 65% of the GBM samples and correlated significantly with improved survival (P < 0.04). We found 3 major Klotho promotor hypermethylation sites located 585-579 bp, 540-533 bp, and 537-534 bp upstream of the transcription start site. Methylated deoxyribonucleic acid immunoprecipitation studies confirmed these results. Notably, the messenger RNA expression in these GBM samples revealed an unexpected linear correlation with methylation of these 3 hypermethylation sites identified in the Klotho promotor. Thus Klotho expression and methylation could predict prognosis in patients with GBM.
Epigenetic regulation in GBM appears to be complicated. Specific CpG islands affect genes or micro RNAs that interact to control Klotho expression. The diverse effects of these islands may be due to unique factors of GBM.
Klotho 是一种与早衰有关的单次跨膜蛋白，通过抑制胰岛素/胰岛素样生长因子-1 和成纤维细胞生长因子途径发挥肿瘤抑制基因的作用。据报道，Klotho 在黑色素瘤、间皮瘤、膀胱癌、乳腺癌、胃癌、宫颈癌、肺癌和肾癌中的表达下调，并与预后不良相关。Klotho 的表达和 Klotho 启动子超甲基化是预测患者预后的因素。
为了研究 Klotho 在胶质母细胞瘤（GBM）中的潜在作用，我们从 Sheba 肿瘤库收集了 22 例 GBM 样本进行了研究。
我们发现，Klotho 信使核糖核酸（RNA）表达增加预示着 GBM 患者的生存时间更长（P=0.03）。采用离子淌度飞行时间质谱法（ionization time-of-flight mass spectrometry），根据 Sequenom EpiTYPER 方案，对 GBM 患者样本的亚硫酸氢盐处理脱氧核糖核酸（deoxyribonucleic acid）进行甲基化分析。在 65%的 GBM 样本中检测到 Klotho 启动子超甲基化，与生存时间显著改善相关（P<0.04）。我们发现 3 个主要的 Klotho 启动子超甲基化位点位于转录起始位点上游的 585-579bp、540-533bp 和 537-534bp 处。甲基化脱氧核糖核酸免疫沉淀研究证实了这些结果。值得注意的是，这些 GBM 样本中的信使 RNA 表达与在 Klotho 启动子中鉴定的这 3 个超甲基化位点的甲基化呈意外线性相关。因此，Klotho 的表达和甲基化可以预测 GBM 患者的预后。
GBM 中的表观遗传调控似乎很复杂。特定的 CpG 岛影响基因或 microRNAs，从而相互作用控制 Klotho 的表达。这些岛的不同影响可能是由于 GBM 的独特因素所致。
