Cancer metastasis and recurrence are potentially lethal. A small number of cancer cell groups called cancer stem cells (CSCs) have both stem cell capacity and cancer-forming ability and are reported to play important roles in cancer metastasis and recurrence. These CSCs are considered to be radiation-resistant (RR). Therefore, understanding the biological effects of radiation on squamous cell carcinoma (SCC) cell lines in vitro and in vivo might be worthwhile to circumvent radiation resistance. Currently, there are no reports on the establishment of RR-SCC cells in serum-free defined culture, which mimics biological mechanisms and prevents instability of using serum in the culture medium. We isolated radiation-resistant strains, designated A431-LDR and A431-HDR, from A431 cells derived from vulval SCC and irradiated them with a total dose of 60 Gy at a low-dose rate (2.2 Gy/d) (RM1000) and a high-dose rate (5 Gy/5.75min) in serum-free defined culture. These cells exhibited high sphere-forming and migration ability in vitro and high tumor-forming ability in nude mice xenografts. Overexpression of KRT13 in A431-RR cells might play a role in its radiation-resistant characteristics. These cells might be useful not only to study cancer stem cells but also to study the circumvention of radiation resistance by novel cancer treatment modalities.

癌症转移和复发可能是致命的。少数被称为癌症干细胞 (CSC) 的癌细胞群同时具有干细胞能力和癌症形成能力，据报道在癌症转移和复发中起重要作用。这些 CSC 被认为是抗辐射 (RR)。因此，了解辐射对体外和体内鳞状细胞癌 (SCC) 细胞系的生物学效应可能有助于规避辐射抗性。目前，没有关于在无血清确定培养中建立 RR-SCC 细胞的报道，它模仿生物学机制并防止在培养基中使用血清的不稳定性。我们分离了抗辐射菌株，命名为 A431-LDR 和 A431-HDR，来自外阴 SCC 的 A431 细胞，并以低剂量率 (2.2 Gy/d) (RM1000) 和高剂量率 (5 Gy/5.75 分钟) 在无血清定义的总剂量下照射它们文化。这些细胞在体外表现出高球形成和迁移能力，在裸鼠异种移植物中表现出高肿瘤形成能力。过度表达A431-RR 细胞中的KRT13可能在其抗辐射特性中发挥作用。这些细胞不仅可用于研究癌症干细胞，还可用于研究通过新型癌症治疗方式规避辐射抗性。