Anthoney D A, McIlwrath A J, Gallagher W M, Edlin A R, Brown R
CRC Department of Medical Oncology, CRC Beatson Laboratories, Glasgow, United Kingdom.
Cancer Res. 1996 Mar 15;56(6):1374-81.
We have examined microsatellite instability and loss of p53 function in human tumor cell line models of acquired anticancer drug resistance. We observe acquisition of an RER(+) phenotype in cell lines selected for resistance to cisplatin or doxorubicin. The majority of independent cisplatin-resistant sublines are RER(+), whereas the parental line shows no evidence of microsatellite instability. Microsatellite mutations in random, nonselected subclones of a cislatin-resistant line are observed in the absence of further drug exposure, suggesting that the RER(+) phenotype is a stable phenotype rather than being transiently induced by DNA damage. Furthermore, a cisplatin-resistant derivative shows reduction in a G:T mismatch recognition activity compared to the parental line. Independent lines selected by multiple exposure to cisplatin show resistance factors of up to a 5-fold by clonogenic assay and have reduced cisplatin-induced apoptosis. The resistant lines that are RER(+) show evidence of loss of p53-dependent functions, as measured by a loss of radiation-induced G(1) arrest and reduced CIP1 mRNA. Induced loss of p53 function by transfection of mutant TP53 does not cause a detectable RER(+) phenotype. We speculate that tolerance of DNA damage and expansion of cells with an RER(+) phenotype may select for reduced ability to engage apoptosis and loss of p53 function.
我们研究了获得性抗癌药物耐药性的人类肿瘤细胞系模型中的微卫星不稳定性和p53功能丧失情况。我们观察到，在选择对顺铂或阿霉素耐药的细胞系中出现了RER(+)表型。大多数独立的顺铂耐药亚系是RER(+)，而亲代细胞系未显示微卫星不稳定性的迹象。在没有进一步药物暴露的情况下，在顺铂耐药细胞系的随机、未选择的亚克隆中观察到微卫星突变，这表明RER(+)表型是一种稳定的表型，而非由DNA损伤短暂诱导产生。此外，与亲代细胞系相比，一种顺铂耐药衍生物的G:T错配识别活性降低。通过克隆形成试验，多次暴露于顺铂所选择的独立细胞系显示出高达5倍的耐药因子，并且顺铂诱导的凋亡减少。RER(+)的耐药细胞系显示出p53依赖性功能丧失的证据，这通过辐射诱导的G(1)期阻滞丧失和CIP1 mRNA减少来衡量。通过转染突变型TP53诱导p53功能丧失不会导致可检测到的RER(+)表型。我们推测，DNA损伤耐受性以及具有RER(+)表型的细胞扩增可能导致凋亡能力降低和p53功能丧失。
