Lemm Sandy, Gebhardt Marcel, Groß Thomas, Richter Susan, Ullrich Martin, Pietzsch Jens
Institute of Radiopharmaceutical Cancer Research, Department of Radiopharmaceutical and Chemical Biology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.
Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Dresden, Germany.
Front Oncol. 2025 Jul 30;15:1517132. doi: 10.3389/fonc.2025.1517132. eCollection 2025.
Patients diagnosed with metastatic pheochromocytoma/paraganglioma (PCC/PGL) have limited treatment options. In some cases, peptide receptor radionuclide therapy (PRRT) is followed by an eruption of metastases, possibly originating from tumor cells with a radioresistant phenotype. However, the underlying mechanisms of radioresistance in PCC/PGL remain largely unknown and appropriate models are missing.
Two genetically modified mouse pheochromocytoma (MPC) cell lines, one positive and one negative for hypoxia-inducible factor 2α expression (MPC+HIF-2α and MPC+EV [empty vector], respectively), were X-ray-conditioned through fractionated irradiation at sublethal doses. Two procedures were tested: one allowed for recovery between each irradiation step (recIR), while the other demanded daily irradiation (dayIR). Changes in cell morphology, growth rates, and DNA repair (γH2AX immunostaining) were characterized in response to irradiation.
We generated two MPC+HIF-2α- and two MPC+EV-derived cell lines that tolerate irradiations with X-rays at dose fractions of 2 Gy per day without significant growth inhibition. All recIR-and dayIR-conditioned cell lines showed increased DNA repair capacity. Morphological changes toward stronger clustering and slower growth were more pronounced in dayIR-conditioned than in recIR-conditioned cell lines. X-ray-conditioned MPC+HIF-2α cells showed the highest increase in resistance to X-ray-treatment with dose fractions up to 5 Gy per day.
The herein established X-ray-conditioned MPC cell lines represent PCC/PGL models with a radioresistant phenotype. Further investigations on the radiation-induced genetic responses of these cell lines, their corresponding tumor spheroids, and tumor allografts in mice will help to elucidate the underlying mechanisms of acquired radioresistance and radionuclide therapy-induced metastatic eruption in PCC/PGL. Lastly, the suitability of advanced PRRT and complementary treatments can be tested to improve theranostic strategies.
被诊断为转移性嗜铬细胞瘤/副神经节瘤（PCC/PGL）的患者治疗选择有限。在某些情况下，肽受体放射性核素治疗（PRRT）后会出现转移灶爆发，可能源于具有放射抗性表型的肿瘤细胞。然而，PCC/PGL中放射抗性的潜在机制仍 largely未知，且缺乏合适的模型。
两种基因改造的小鼠嗜铬细胞瘤（MPC）细胞系，一种缺氧诱导因子2α表达阳性，另一种为阴性（分别为MPC + HIF - 2α和MPC + EV[空载体]），通过亚致死剂量的分次照射进行X射线预处理。测试了两种程序：一种在每个照射步骤之间允许恢复（recIR），而另一种要求每日照射（dayIR）。针对照射，对细胞形态、生长速率和DNA修复（γH2AX免疫染色）的变化进行了表征。
我们生成了两种源自MPC + HIF - 2α和两种源自MPC + EV的细胞系，它们能够耐受每天2 Gy剂量分次的X射线照射，且无明显生长抑制。所有recIR和dayIR预处理的细胞系均显示出DNA修复能力增强。与recIR预处理的细胞系相比，dayIR预处理的细胞系中向更强聚集和更慢生长的形态学变化更为明显。X射线预处理的MPC + HIF - 2α细胞对每天高达5 Gy剂量分次的X射线治疗的抗性增加最为显著。
本文建立的X射线预处理的MPC细胞系代表具有放射抗性表型的PCC/PGL模型。对这些细胞系、其相应的肿瘤球体以及小鼠体内肿瘤异体移植的辐射诱导遗传反应的进一步研究，将有助于阐明PCC/PGL中获得性放射抗性和放射性核素治疗诱导的转移灶爆发的潜在机制。最后，可以测试先进PRRT和辅助治疗的适用性，以改善诊疗策略。
