Department of Radiation Oncology, LMU Klinikum, LMU Munich, 81377, Munich, Germany.
Department of Physics, LMU Munich, 85748, Garching, Germany.
Radiat Oncol. 2021 Aug 19;16(1):159. doi: 10.1186/s13014-021-01883-6.
Invasiveness is a major factor contributing to metastasis of tumour cells. Given the broad variety and plasticity of invasion mechanisms, assessing potential metastasis-promoting effects of irradiation for specific mechanisms is important for further understanding of potential adverse effects of radiotherapy. In fibroblast-led invasion mechanisms, fibroblasts produce tracks in the extracellular matrix in which cancer cells with epithelial traits can follow. So far, the influence of irradiation on this type of invasion mechanisms has not been assessed.
By matrix-embedding coculture spheroids consisting of breast cancer cells (MCF-7, BT474) and normal fibroblasts, we established a model for fibroblast-led invasion. To demonstrate applicability of this model, spheroid growth and invasion behaviour after irradiation with 5 Gy were investigated by microscopy and image analysis.
When not embedded, irradiation caused a significant growth delay in the spheroids. When irradiating the spheroids with 5 Gy before embedding, we find comparable maximum migration distance in fibroblast monoculture and in coculture samples as seen in unirradiated samples. Depending on the fibroblast strain, the number of invading cells remained constant or was reduced.
In this spheroid model and with the cell lines and fibroblast strains used, irradiation does not have a major invasion-promoting effect. 3D analysis of invasiveness allows to uncouple effects on invading cell number and maximum invasion distance when assessing radiation effects.
侵袭性是肿瘤细胞转移的一个主要因素。鉴于侵袭机制的广泛多样性和可塑性，评估特定机制中照射对促进转移的潜在影响对于进一步了解放射治疗的潜在不良影响很重要。在成纤维细胞主导的侵袭机制中，成纤维细胞在细胞外基质中产生轨迹，具有上皮特征的癌细胞可以沿着这些轨迹进行侵袭。到目前为止，还没有评估过照射对这种侵袭机制的影响。
通过基质包埋共培养球体，由乳腺癌细胞（MCF-7、BT474）和正常成纤维细胞组成，我们建立了成纤维细胞主导的侵袭模型。为了证明该模型的适用性，通过显微镜和图像分析研究了照射 5Gy 后球体的生长和侵袭行为。
当不进行包埋时，照射会导致球体的生长明显延迟。当在包埋前用 5Gy 照射球体时，我们发现成纤维细胞单培养和共培养样本中的最大迁移距离与未照射样本相似。根据成纤维细胞株的不同，侵袭细胞的数量保持不变或减少。
在该球体模型中，并且使用所使用的细胞系和成纤维细胞株，照射没有促进侵袭的主要作用。对侵袭性的 3D 分析可以在评估辐射效应时，将对侵袭细胞数量和最大侵袭距离的影响分离开来。
