Palma Alessandra, Grande Sveva, Luciani Anna Maria, Mlynárik Vladimír, Guidoni Laura, Viti Vincenza, Rosi Antonella
Department of Technology and Health, Istituto Superiore di Sanità, Rome, Italy; INFN Sezione di Roma, Rome, Italy.
Department of Biomedical Imaging and Image-Guided Therapy, High-Field MR Center, Medical University of Vienna , Vienna , Austria.
Front Oncol. 2016 Apr 28;6:105. doi: 10.3389/fonc.2016.00105. eCollection 2016.
Multicellular tumor spheroids are an important model system to investigate the response of tumor cells to radio- and chemotherapy. They share more properties with the original tumor than cells cultured as 2D monolayers do, which helps distinguish the intrinsic properties of monolayer cells from those induced during cell aggregation in 3D spheroids. The paper investigates some metabolic aspects of small tumor spheroids of breast cancer and their originating MCF-7 cells, grown as monolayer, by means of high-resolution (HR) (1)H NMR spectroscopy and MR microimaging before and after gamma irradiation. The spectra of spheroids were characterized by higher intensity of mobile lipids, mostly neutral lipids, and glutamine (Gln) signals with respect to their monolayer cells counterpart, mainly owing to the lower oxygen supply in spheroids. Morphological changes of small spheroids after gamma-ray irradiation, such as loss of their regular shape, were observed by MR microimaging. Lipid signal intensity increased after irradiation, as evidenced in both MR localized spectra of the single spheroid and in HR NMR spectra of spheroid suspensions. Furthermore, the intense Gln signal from spectra of irradiated spheroids remained unchanged, while the low Gln signal observed in monolayer cells increased after irradiation. Similar results were observed in cells grown in hypoxic conditions. The different behavior of Gln in 2D monolayers and in 3D spheroids supports the hypothesis that a lower oxygen supply induces both an upregulation of Gln synthetase and a downregulation of glutaminases with the consequent increase in Gln content, as already observed under hypoxic conditions. The data herein indicate that (1)H NMR spectroscopy can be a useful tool for monitoring cell response to different constraints. The use of spheroid suspensions seems to be a feasible alternative to localized spectroscopy since similar effects were found after radiation treatment.
多细胞肿瘤球体是研究肿瘤细胞对放疗和化疗反应的重要模型系统。与二维单层培养的细胞相比，它们与原始肿瘤具有更多共同特性，这有助于区分单层细胞的内在特性与三维球体中细胞聚集过程中诱导产生的特性。本文通过高分辨率（HR）氢核磁共振波谱和磁共振显微成像技术，研究了乳腺癌小肿瘤球体及其单层培养的起源细胞MCF-7在伽马射线照射前后的一些代谢方面。与单层细胞相比，球体的光谱特征是可移动脂质（主要是中性脂质）和谷氨酰胺（Gln）信号强度更高，这主要是由于球体中氧气供应较低。通过磁共振显微成像观察到伽马射线照射后小球体的形态变化，如失去规则形状。照射后脂质信号强度增加，这在单个球体的磁共振局部光谱和球体悬浮液的高分辨率核磁共振光谱中都得到了证实。此外，照射后球体光谱中强烈的Gln信号保持不变，而单层细胞中观察到的低Gln信号在照射后增加。在低氧条件下培养的细胞中也观察到了类似结果。二维单层细胞和三维球体中Gln的不同行为支持了这样的假设，即较低的氧气供应会诱导谷氨酰胺合成酶上调和谷氨酰胺酶下调，从而导致Gln含量增加，这在低氧条件下已被观察到。本文数据表明氢核磁共振波谱可作为监测细胞对不同限制条件反应的有用工具。由于在放射治疗后发现了类似的效果，使用球体悬浮液似乎是局部光谱学的一种可行替代方法。
