Johannessen T-C A, Wang J, Skaftnesmo K-O, Sakariassen P Ø, Enger P Ø, Petersen K, Øyan A M, Kalland K-H, Bjerkvig R, Tysnes B B
NorLux Neuro Oncology, Department of Biomedicine, Bergen, Norway.
Neuropathol Appl Neurobiol. 2009 Aug;35(4):380-93. doi: 10.1111/j.1365-2990.2008.01008.x.
Cancer stem-like cells might have important functions in chemoresistance. We have developed a model where highly infiltrative brain tumours with a stem-like phenotype were established by orthotopic transplantation of human glioblastomas to immunodeficient rats. Serial passaging gradually transformed the tumours into a less invasive and more angiogenic phenotype (high-generation tumours). The invasive phenotype (low-generation tumours) was characterized by an increase in stem cell markers and increased phosphorylation of kinases in the phosphatidylinositol 3-kinase (PI3K)/AKT pathway. These markers were reduced in the serially passaged vascular tumours. The present study was aimed at investigating how the two phenotypes responded in vitro to doxorubicin, a clinically potent cytotoxic drug for solid tumours.
Biopsy spheroids were implanted and passaged intracranially in nude rats. Gene expression and protein analyses were performed, and drug sensitivity was assessed.
Microarray analysis revealed gene ontology categories connected to developmental aspects and negative regulators of differentiation, especially in the infiltrative stem cell-like tumours. The highly invasive stem-like phenotype was chemoresistant compared with the angiogenic phenotype. By interfering with the PI3K it was possible to sensitize tumour spheroids to chemotherapy. Real-time quantitative polymerase chain reaction showed downregulation of the stem cell markers Nestin and Musashi-1 in low-generation biopsy spheroids following PI3K inhibition.
Highly invasive tumours with a stem-like phenotype are more chemoresistant than angiogenic tumours derived from the same patients. We suggest that treatment resistance in glioblastomas can be related to PI3K/AKT activity in stem-like tumour cells, and that targeted interference with the PI3K/AKT pathway might differentiate and sensitize this subpopulation to chemotherapy.
癌症干细胞样细胞可能在化疗耐药中发挥重要作用。我们建立了一种模型，通过将人胶质母细胞瘤原位移植到免疫缺陷大鼠体内，形成具有干细胞样表型的高浸润性脑肿瘤。连续传代逐渐将肿瘤转变为侵袭性较低、血管生成较多的表型（高代肿瘤）。侵袭性表型（低代肿瘤）的特征是干细胞标志物增加以及磷脂酰肌醇3激酶（PI3K）/AKT途径中激酶的磷酸化增加。这些标志物在连续传代的血管肿瘤中减少。本研究旨在调查这两种表型在体外对阿霉素（一种临床上对实体瘤有效的细胞毒性药物）的反应。
将活检球体植入裸鼠颅内并传代。进行基因表达和蛋白质分析，并评估药物敏感性。
微阵列分析揭示了与发育方面和分化负调节因子相关的基因本体类别，特别是在浸润性干细胞样肿瘤中。与血管生成表型相比，高侵袭性干细胞样表型对化疗耐药。通过干扰PI3K可以使肿瘤球体对化疗敏感。实时定量聚合酶链反应显示，PI3K抑制后，低代活检球体中干细胞标志物巢蛋白和神经胶质瘤相关蛋白1的表达下调。
具有干细胞样表型的高侵袭性肿瘤比来自同一患者的血管生成性肿瘤对化疗更耐药。我们认为胶质母细胞瘤的治疗耐药可能与干细胞样肿瘤细胞中的PI3K/AKT活性有关，并且对PI3K/AKT途径的靶向干扰可能使该亚群分化并对化疗敏感。
