Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA.
Department of Radiation Oncology, School of Medicine, Vanderbilt University, Nashville, TN, USA.
Int J Radiat Biol. 2021;97(12):1675-1686. doi: 10.1080/09553002.2021.1976861. Epub 2021 Sep 29.
Chordoma is a locally aggressive tumor that most commonly affects the base of the skull/clivus, cervical, and sacral spine. Conventional radiotherapy (RT), cannot be safely increased further to improve disease control due to the risk of toxicity to the surrounding critical structures. Tumor-targeted hyperthermia (HT) combined with Proton Beam Radiation Therapy (PBRT) is known to act as a potent radiosensitizer in cancer control. In this study, we investigated whether PBRT efficacy for chordoma can be enhanced in combination with HT as a radiosensitizer.
Human chordoma cell lines, U-CH2 and Mug-chor1 were treated in vitro with HT followed by PBRT with variable doses. The colony-forming assay was performed, and dose-response was characterized by linear-quadratic model fits. HSP-70 and Brachyury (TBXT) biomarkers for chordoma aggression levels were quantified by western blot analysis. Gene microarray analysis was performed by U133 Arrays. Pathway Analysis was also performed using IPA bioinformatic software.
Our findings in both U-CH and Mug-Chor1 cell lines demonstrate that hyperthermia followed by PBRT has an enhanced cell killing effect when compared with PBRT-alone ( < .01). Western blot analysis showed HT decreased the expression of Brachyury protein ( < .05), which is considered a biomarker for chordoma tumor aggression. HT with PBRT also exhibited an RT-dose-dependent decrease of Brachyury expression ( < .05). We also observed enhanced HSP-70 expression due to HT, RT, and HT + RT combined in both cell lines. Interestingly, genomic data showed 344 genes expressed by the treatment of HT + RT compared to HT (68 genes) or RT (112 genes) as individual treatment. We also identified activation of death receptor and apoptotic pathway in HT + RT treated cells.
We found that Hyperthermia (HT) combined with Proton Beam Radiation (PBRT) could significantly increase chordoma cell death by activating the death receptor pathway and apoptosis which has the promise to treat metastatic chordoma.
软骨肉瘤是一种局部侵袭性肿瘤，最常发生于颅底/斜坡、颈椎和骶骨脊柱。由于周围关键结构毒性的风险，常规放疗（RT）不能进一步安全增加以提高疾病控制率。肿瘤靶向热疗（HT）联合质子束放射治疗（PBRT）已被证明在癌症控制中作为一种有效的放射增敏剂。在这项研究中，我们研究了 HT 作为放射增敏剂与 PBRT 联合是否可以增强软骨肉瘤的疗效。
体外培养人软骨肉瘤细胞系 U-CH2 和 Mug-chor1，先用 HT 处理，然后用不同剂量的 PBRT 处理。通过集落形成试验进行检测，并通过线性二次模型拟合来描述剂量反应。通过 Western blot 分析定量 HSP-70 和 Brachyury（TBXT）作为软骨肉瘤侵袭水平的生物标志物。通过 U133 微阵列进行基因微阵列分析。还使用 IPA 生物信息学软件进行了途径分析。
我们在 U-CH 和 Mug-Chor1 细胞系中的发现表明，与单独使用 PBRT 相比，热疗后再进行 PBRT 具有更强的细胞杀伤作用（<0.01）。Western blot 分析显示 HT 降低了 Brachyury 蛋白的表达（<0.05），Brachyury 被认为是软骨肉瘤肿瘤侵袭的生物标志物。HT 联合 PBRT 也表现出 Brachyury 表达的 RT 剂量依赖性降低（<0.05）。我们还观察到由于 HT、RT 和 HT+RT 联合作用，在两种细胞系中 HSP-70 表达增强。有趣的是，基因组数据显示与 HT（68 个基因）或 RT（112 个基因）单独治疗相比，HT+RT 治疗有 344 个基因表达。我们还发现 HT+RT 处理的细胞中死亡受体和凋亡途径被激活。
我们发现热疗（HT）联合质子束放射（PBRT）通过激活死亡受体途径和凋亡显著增加软骨肉瘤细胞死亡，有望治疗转移性软骨肉瘤。
