Bennett Daine T, Deng Xin-Sheng, Yu Jessica A, Bell Marshall T, Mauchley David C, Meng Xianzhong, Reece T Brett, Fullerton David A, Weyant Michael J
Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
Ann Thorac Surg. 2014 Aug;98(2):439-45; discussion 445-6. doi: 10.1016/j.athoracsur.2014.04.044. Epub 2014 Jun 10.
Lung cancer stem cells (CSCs) are a subpopulation of cells that drive growth, invasiveness, and resistance to therapy. Inflammatory eicosanoids are critical to maintain this malignant subpopulation. Secretory phospholipase A2 group IIa (sPLA2) is an important mediator of the growth and invasive potential of human lung cancer cells and regulates eicosanoid production. We hypothesized that sPLA2 plays a role in the maintenance of lung CSCs.
Cancer stem cells from lung adenocarcinoma cell lines H125 and A549 were isolated using aldehyde dehydrogenase activity and flow cytometry. Protein and mRNA levels for sPLA2 were compared between sorted cells using Western blotting and quantitative reverse transcriptase-polymerase chain reaction techniques. Chemical inhibition of sPLA2 and short-hairpin RNA knockdown of sPLA2 were used to evaluate effects on tumorsphere formation.
Lung CSCs were isolated in 8.9%±4.1% (mean±SD) and 4.1%±1.6% of H125 and A549 cells respectively. Both sPLA2 protein and mRNA expression were significantly elevated in the CSC subpopulation of H125 (p=0.002) and A549 (p=0.005; n=4). Knockdown of sPLA2 significantly reduced tumorsphere formation in H125 (p=0.026) and A549 (p=0.001; n=3). Chemical inhibition of sPLA2 resulted in dose-dependent reduction in tumorsphere formation in H125 (p=0.003) and A549 (p=0.076; n=3).
Lung CSCs express higher levels of sPLA2 than the non-stem cell population. Our findings that viral knockdown and chemical inhibition of sPLA2 reduce tumorsphere formation in lung cancer cells demonstrate for the first time that sPLA2 plays an important role in CSCs. These findings suggest that sPLA2 may be an important therapeutic target for human lung cancer.
肺癌干细胞（CSCs）是一类驱动肿瘤生长、侵袭及产生治疗抵抗的细胞亚群。炎性类二十烷酸对于维持这一恶性亚群至关重要。分泌型磷脂酶A2 IIa组（sPLA2）是人类肺癌细胞生长和侵袭潜能的重要介质，并调节类二十烷酸的产生。我们推测sPLA2在肺癌干细胞的维持中发挥作用。
利用醛脱氢酶活性和流式细胞术从肺腺癌细胞系H125和A549中分离癌症干细胞。使用蛋白质印迹法和定量逆转录-聚合酶链反应技术比较分选细胞中sPLA2的蛋白质和mRNA水平。采用sPLA2的化学抑制和短发夹RNA敲低来评估对肿瘤球形成的影响。
在H125和A549细胞中分别有8.9%±4.1%（平均值±标准差）和4.1%±1.6%的细胞被分离为肺癌干细胞。sPLA2的蛋白质和mRNA表达在H125（p = 0.002）和A549（p = 0.005；n = 4）的癌症干细胞亚群中均显著升高。sPLA2的敲低显著减少了H125（p = 0.026）和A549（p = 0.001；n = 3）中的肿瘤球形成。sPLA2的化学抑制导致H125（p = 0.003）和A549（p = 0.076；n = 3）中肿瘤球形成呈剂量依赖性减少。
肺癌干细胞比非干细胞群体表达更高水平的sPLA2。我们的研究结果表明，sPLA2的病毒敲低和化学抑制可减少肺癌细胞中的肿瘤球形成，首次证明sPLA2在癌症干细胞中发挥重要作用。这些发现表明sPLA2可能是人类肺癌的一个重要治疗靶点。
