Daugaard Iben, Knudsen Alice, Kjeldsen Tina E, Hager Henrik, Hansen Lise Lotte
Department of Biomedicine, Aarhus University, Bartholins Allé 6, DK-8000 Aarhus C, Denmark.
Department of Biomedicine, Aarhus University, Bartholins Allé 6, DK-8000 Aarhus C, Denmark.
Exp Mol Pathol. 2017 Jun;102(3):484-491. doi: 10.1016/j.yexmp.2017.05.012. Epub 2017 May 13.
Lung cancer has the highest mortality rate amongst human cancers and the majority of deaths can be attributed to metastatic spread. The miR-34 family includes three tumor suppressive miRs: miR-34a, miR-34b and miR-34c. miR-34 downregulation is a frequent observation in human malignancies and is often attributed to hypermethylation of the miR-34a and miR-34b/c promoters. Here, the potential association between aberrant miR-34 expression and promoter methylation and distant metastases formation in lung adenocarcinoma (LAC) is investigated. The expression levels of miR-34a, miR-34b and miR-34c, as well as the methylation status of the miR-34a and miR-34b/c promoters were determined in a LAC patient cohort comprising 26 non-metastasizing and 26 metastasizing primary LACs, as well as 24 paired distant metastases and 25 tumor-adjacent normal lung samples using RT-qPCR and Methylation-Sensitive High Resolution Melting (MS-HRM) analysis. No difference in expression was observed for miR-34a when comparing metastasizing and non-metastasizing LACs (p=0.793). For both miR-34b and miR-34c, a significantly lower expression level was determined in metastasizing LACs compared to non-metastasizing LACs (p=0.0005 and p=0.002) with similarly decreased expression levels observed in the paired distant metastases. Hypermethylation was detected in 35/51 LACs compared to 0/25 tumor-adjacent normal lungs for the miR-34a promoter (p<0.0001). Similarly, 18/51 LACs compared to 1/25 tumor-adjacent normal lungs showed hypermethylation of the miR-34b/c promoter (p=0.003). No difference in methylation was observed between metastasizing and non-metastasizing LACs for neither the miR-34a (p=0.832) nor the miR-34b/c (p=0.900) promoter. In conclusion, miR-34a and miR-34b/c promoter hypermethylation is a frequent event in LAC occurring in 68.7% and 35.3% of tested cases (n=51), respectively. Low miR-34b and miR-34c expression was associated with distant metastases formation in LAC. These changes can be targeted as novel biomarkers in LAC.
肺癌是人类癌症中死亡率最高的，大多数死亡可归因于转移扩散。miR-34家族包括三种具有肿瘤抑制作用的微小RNA：miR-34a、miR-34b和miR-34c。在人类恶性肿瘤中经常观察到miR-34下调，这通常归因于miR-34a和miR-34b/c启动子的高甲基化。在此，研究了肺腺癌（LAC）中异常miR-34表达与启动子甲基化及远处转移形成之间的潜在关联。使用逆转录定量聚合酶链反应（RT-qPCR）和甲基化敏感高分辨率熔解（MS-HRM）分析，在一个由26例无转移和26例有转移的原发性LAC、24对配对的远处转移灶以及25例肿瘤邻近正常肺组织样本组成的LAC患者队列中，测定了miR-34a、miR-34b和miR-34c的表达水平，以及miR-34a和miR-34b/c启动子的甲基化状态。比较有转移和无转移的LAC时，未观察到miR-34a表达有差异（p=0.793）。对于miR-34b和miR-34c，与无转移的LAC相比，有转移的LAC中测定的表达水平显著更低（p=0.0005和p=0.002），在配对的远处转移灶中也观察到类似的表达水平降低。与25例肿瘤邻近正常肺组织中miR-34a启动子甲基化0/25相比，在51例LAC中有35例检测到高甲基化（p<0.0001）。同样，与25例肿瘤邻近正常肺组织中miR-34b/c启动子甲基化1/25相比，51例LAC中有18例显示高甲基化（p=0.003）。对于miR-34a（p=0.832）和miR-34b/c（p=0.900）启动子，有转移和无转移的LAC之间未观察到甲基化差异。总之，miR-34a和miR-34b/c启动子高甲基化在LAC中是常见事件，分别发生在68.7%和35.3%的检测病例（n=51）中。低miR-34b和miR-34c表达与LAC中的远处转移形成相关。这些变化可作为LAC中的新型生物标志物。
