Matthews Quinn, Isabelle Martin, Harder Samantha J, Smazynski Julian, Beckham Wayne, Brolo Alexandre G, Jirasek Andrew, Lum Julian J
Trev and Joyce Deeley Research Centre, BC Cancer Agency, Victoria, BC, Canada; Department of Medical Physics, BC Cancer Agency, Victoria, BC, Canada.
Trev and Joyce Deeley Research Centre, BC Cancer Agency, Victoria, BC, Canada; Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada.
PLoS One. 2015 Aug 17;10(8):e0135356. doi: 10.1371/journal.pone.0135356. eCollection 2015.
Altered cellular metabolism is a hallmark of tumor cells and contributes to a host of properties associated with resistance to radiotherapy. Detection of radiation-induced biochemical changes can reveal unique metabolic pathways affecting radiosensitivity that may serve as attractive therapeutic targets. Using clinically relevant doses of radiation, we performed label-free single cell Raman spectroscopy on a series of human cancer cell lines and detected radiation-induced accumulation of intracellular glycogen. The increase in glycogen post-irradiation was highest in lung (H460) and breast (MCF7) tumor cells compared to prostate (LNCaP) tumor cells. In response to radiation, the appearance of this glycogen signature correlated with radiation resistance. Moreover, the buildup of glycogen was linked to the phosphorylation of GSK-3β, a canonical modulator of cell survival following radiation exposure and a key regulator of glycogen metabolism. When MCF7 cells were irradiated in the presence of the anti-diabetic drug metformin, there was a significant decrease in the amount of radiation-induced glycogen. The suppression of glycogen by metformin following radiation was associated with increased radiosensitivity. In contrast to MCF7 cells, metformin had minimal effects on both the level of glycogen in H460 cells following radiation and radiosensitivity. Our data demonstrate a novel approach of spectral monitoring by Raman spectroscopy to assess changes in the levels of intracellular glycogen as a potential marker and resistance mechanism to radiation therapy.
细胞代谢改变是肿瘤细胞的一个标志，并且促成了一系列与放疗抗性相关的特性。检测辐射诱导的生化变化能够揭示影响放射敏感性的独特代谢途径，这些途径可能成为有吸引力的治疗靶点。我们使用临床相关剂量的辐射，对一系列人类癌细胞系进行了无标记单细胞拉曼光谱分析，并检测到辐射诱导的细胞内糖原积累。与前列腺（LNCaP）肿瘤细胞相比，照射后糖原增加在肺（H460）和乳腺（MCF7）肿瘤细胞中最为明显。响应辐射时，这种糖原特征的出现与辐射抗性相关。此外，糖原的积累与GSK-3β的磷酸化有关，GSK-3β是辐射暴露后细胞存活的经典调节因子以及糖原代谢的关键调节因子。当MCF7细胞在抗糖尿病药物二甲双胍存在下接受照射时，辐射诱导的糖原量显著减少。辐射后二甲双胍对糖原的抑制与放射敏感性增加有关。与MCF7细胞不同，二甲双胍对H460细胞辐射后的糖原水平和放射敏感性影响极小。我们的数据展示了一种通过拉曼光谱进行光谱监测的新方法，以评估细胞内糖原水平的变化，作为放疗的潜在标志物和抗性机制。
