Asada N, Tsuchiya H, Tomita K
Department of Orthopedic Surgery, School of Medicine, Kanazawa University, Ishikawa, Japan.
Anticancer Res. 1999 Nov-Dec;19(6B):5131-7.
Initial p53 status is a useful determinant of chemoresistance or chemosensitivity of primary tumors, however, it remains unclear whether p53 status is a critical chemoresistant marker in tumors that acquire drug-resistance after the initiation of chemotherapy. We investigated the relationship between p53 status and the development of resistance to cisplatin in osteosarcoma cell lines.
Cisplatin-sensitive human osteosarcoma OST cells and acquired cisplatin-resistant OST/R cells derived from OST cells were used. Single-strand conformation polymorphism (SSCP) analysis of exons 5 to 8, and immunohistochemistry using anti-p53 antibodies were analyzed to detect mutations of p53. Fluorescence in situ hybridization (FISH) and enzyme immunoassay (EIA) were performed to detect deletions of p53.
SSCP and immunohistochemistry revealed that both cell lines had wild-type p53 gene and protein. However, in OST/R cells, genomic instability of chromosome 17 and de novo deletion of the p53 gene located in chromosome 17p were detected by FISH. The constitutive levels of wild-type p53 protein measured by EIA were significantly lower in OST/R cells than in OST cells. Furthermore, p53 induction was lost in OST/R cells after cisplatin exposure.
De novo deletions of the p53 gene and wild-type p53 were associated with the acquisition of cisplatin-resistance in osteosarcoma.
初始p53状态是原发性肿瘤化疗耐药或化疗敏感性的一个有用决定因素，然而，在化疗开始后获得耐药性的肿瘤中，p53状态是否为关键的化疗耐药标志物仍不清楚。我们研究了骨肉瘤细胞系中p53状态与顺铂耐药性产生之间的关系。
使用顺铂敏感的人骨肉瘤OST细胞以及从OST细胞衍生而来的获得性顺铂耐药OST/R细胞。对第5至8外显子进行单链构象多态性（SSCP）分析，并使用抗p53抗体进行免疫组织化学分析以检测p53突变。进行荧光原位杂交（FISH）和酶免疫测定（EIA）以检测p53缺失。
SSCP和免疫组织化学显示两种细胞系均具有野生型p53基因和蛋白。然而，在OST/R细胞中，通过FISH检测到17号染色体的基因组不稳定以及位于17p染色体上的p53基因的新生缺失。通过EIA测定的野生型p53蛋白的组成水平在OST/R细胞中显著低于OST细胞。此外，顺铂暴露后OST/R细胞中p53诱导缺失。
p53基因的新生缺失和野生型p53与骨肉瘤中顺铂耐药性的获得有关。
