基于细胞红外光谱预测乙酰化细胞的辐射敏感性

组蛋白乙酰化是表观遗传修饰的一种重要方式。肿瘤细胞的组蛋白大部分呈现低乙酰化状态，而组蛋白去乙酰化酶抑制剂（histone deacetylase inhibitor，HDACi）可以增加肿瘤细胞的乙酰化水平，诱导细胞周期阻滞及凋亡。曲古菌素A （trichostatin A，TSA）是组蛋白去乙酰化酶抑制剂的代表药物之一，能够提高肿瘤细胞组蛋白和非组蛋白的乙酰化水平。傅里叶变换红外（Fourier Transform Infrared，FTIR）光谱可以对无染色、无标记的生物样品进行无损检测，具有特征性明显、快速、分辨率高、重复性好等优点，已被广泛用于细胞的微观生物过程的研究。本文利用红外光谱技术结合免疫荧光技术的手段，研究TSA处理细胞后的乙酰化作用效果，发现红外光谱中甲基与亚甲基的伸缩振动强度之比能够表征细胞内的乙酰化水平变化，然后基于红外光谱的分析结果预测了乙酰化状态不同的细胞辐射敏感性的变化。结果表明，乙酰化细胞的辐射损伤效应可以通过甲基与亚甲基的伸缩振动强度之比进行评价，且该比值与细胞的辐射敏感性呈正相关，表明红外光谱技术可以辅助预测细胞的辐射敏感性，并进行细胞表观遗传学特征与辐射效应关系的研究。Histone acetylation is one of important epigenetic modifications, and histone in most of tumor cells shows low acetylation state. However, histone deacetylase inhibitor (HDACi) can correct abnormal acetylation status, induce cell cycle arrest and apoptosis. Trichostatin A (TSA) is one of the representatives of histone deacetylase inhibitors, which can inhibit histone deacetylase, increase the acetylation level of histone and nonhistone in cell. Fourier transform infrared (FTIR) spectroscopy is a powerful analytical tool which can detect nondestructively, quatitatively and quantitatively biological samples without bio-tagging and bio-labeling. FTIR spectroscopy technology has multiple advantages, including finger-print characteristics, rapid analysis, high resolution and good repeatability. Therefore, it has been widely used in the research of biological processes. This work applied FTIR spectroscopy to study the changes in cells treated with TSA, compared the acetylation level according to FTIR intensity ratio of methyl to methylene stretching vibration, and based on the FTIR analysis predicted the radiosensitivity of the cells with different acetylation levels. As a result, we have verified that the damage caused by radiation in acetylated cells can be evaluated by the ratio of methyl and methylene intensity which is positively correlated with cellular radiosensitivity. Therefore, this work demonstrates that FTIR spectroscopy can be useful for the prediction of radiosensitivity and may also open a door for the study of relationship between epigenetics and radiation bio-effects.

Prediction of Radiosensitivity of Acetylated Cell Through FTIR Spectroscopy

Histone acetylation is one of important epigenetic modifications, and histone in most of tumor cells shows low acetylation state. However, histone deacetylase inhibitor (HDACi) can correct abnormal acetylation status, induce cell cycle arrest and apoptosis. Trichostatin A (TSA) is one of the representatives of histone deacetylase inhibitors, which can inhibit histone deacetylase, increase the acetylation level of histone and nonhistone in cell. Fourier transform infrared (FTIR) spectroscopy is a powerful analytical tool which can detect nondestructively, quatitatively and quantitatively biological samples without bio-tagging and bio-labeling. FTIR spectroscopy technology has multiple advantages, including finger-print characteristics, rapid analysis, high resolution and good repeatability. Therefore, it has been widely used in the research of biological processes. This work applied FTIR spectroscopy to study the changes in cells treated with TSA, compared the acetylation level according to FTIR intensity ratio of methyl to methylene stretching vibration, and based on the FTIR analysis predicted the radiosensitivity of the cells with different acetylation levels. As a result, we have verified that the damage caused by radiation in acetylated cells can be evaluated by the ratio of methyl and methylene intensity which is positively correlated with cellular radiosensitivity. Therefore, this work demonstrates that FTIR spectroscopy can be useful for the prediction of radiosensitivity and may also open a door for the study of relationship between epigenetics and radiation bio-effects.