Sahlberg Sara Häggblad, Spiegelberg Diana, Glimelius Bengt, Stenerlöw Bo, Nestor Marika
Section of Biomedical Radiation Sciences, Department of Radiology, Oncology and Radiation Science, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden.
Section of Oncology, Department of Radiology, Oncology and Radiation Science, Uppsala University, Uppsala, Sweden.
PLoS One. 2014 Apr 23;9(4):e94621. doi: 10.1371/journal.pone.0094621. eCollection 2014.
The cell surface proteins CD133, CD24 and CD44 are putative markers for cancer stem cell populations in colon cancer, associated with aggressive cancer types and poor prognosis. It is important to understand how these markers may predict treatment outcomes, determined by factors such as radioresistance. The scope of this study was to assess the connection between EGFR, CD133, CD24, and CD44 (including isoforms) expression levels and radiation sensitivity, and furthermore analyze the influence of AKT isoforms on the expression patterns of these markers, to better understand the underlying molecular mechanisms in the cell. Three colon cancer cell-lines were used, HT-29, DLD-1, and HCT116, together with DLD-1 isogenic AKT knock-out cell-lines. All three cell-lines (HT-29, HCT116 and DLD-1) expressed varying amounts of CD133, CD24 and CD44 and the top ten percent of CD133 and CD44 expressing cells (CD133high/CD44high) were more resistant to gamma radiation than the ten percent with lowest expression (CD133low/CD44low). The AKT expression was lower in the fraction of cells with low CD133/CD44. Depletion of AKT1 or AKT2 using knock out cells showed for the first time that CD133 expression was associated with AKT1 but not AKT2, whereas the CD44 expression was influenced by the presence of either AKT1 or AKT2. There were several genes in the cell adhesion pathway which had significantly higher expression in the AKT2 KO cell-line compared to the AKT1 KO cell-line; however important genes in the epithelial to mesenchymal transition pathway (CDH1, VIM, TWIST1, SNAI1, SNAI2, ZEB1, ZEB2, FN1, FOXC2 and CDH2) did not differ. Our results demonstrate that CD133high/CD44high expressing colon cancer cells are associated with AKT and increased radiation resistance, and that different AKT isoforms have varying effects on the expression of cancer stem cell markers, which is an important consideration when targeting AKT in a clinical setting.
细胞表面蛋白CD133、CD24和CD44是结肠癌中癌症干细胞群体的假定标志物，与侵袭性癌症类型和不良预后相关。了解这些标志物如何预测由放射抗性等因素决定的治疗结果很重要。本研究的范围是评估表皮生长因子受体（EGFR）、CD133、CD24和CD44（包括亚型）表达水平与放射敏感性之间的联系，此外分析AKT亚型对这些标志物表达模式的影响，以更好地理解细胞中的潜在分子机制。使用了三种结肠癌细胞系，HT-29、DLD-1和HCT116，以及DLD-1同基因AKT敲除细胞系。所有三种细胞系（HT-29、HCT116和DLD-1）均表达不同量的CD133、CD24和CD44，且表达CD133和CD44的细胞中前10%（CD133高/CD44高）比表达最低的10%（CD133低/CD44低）对γ射线更具抗性。在CD133/CD44低的细胞部分中AKT表达较低。使用敲除细胞耗尽AKT1或AKT2首次表明，CD133表达与AKT1相关而与AKT2无关，而CD44表达受AKT1或AKT2存在的影响。与AKT1敲除细胞系相比，细胞粘附途径中有几个基因在AKT2敲除细胞系中表达明显更高；然而，上皮-间质转化途径中的重要基因（CDH1、VIM、TWIST1、SNAI1、SNAI2、ZEB1、ZEB2、FN1、FOXC2和CDH2）没有差异。我们的结果表明，表达CD133高/CD44高的结肠癌细胞与AKT相关且放射抗性增加，并且不同的AKT亚型对癌症干细胞标志物的表达有不同影响，这在临床环境中靶向AKT时是一个重要的考虑因素。
