Suzuki N, Iida S, Yamamori H, Ishizuka T, Takakubo Y
CHIBA UNIV,SCH MED,DEPT LAB MED,CHUO KU,CHIBA 250,JAPAN. CHIBA UNIV,SCH MED,DEPT SURG,CHUO KU,CHIBA 250,JAPAN. NATL TOSEI HOSP,DEPT NEUROSURG,SHIMIZU,SHIZUOKA 411,JAPAN.
Int J Oncol. 1996 Aug;9(2):297-303. doi: 10.3892/ijo.9.2.297.
The human cell line F-IFr is a variant with an increased resistance to cell proliferation inhibition (CPI) by human interferon (HuLFN)-beta, established from RSa cells with high sensitivity to CPI. The parent RSa cells were recently found to be unusually hypermutable after irradiation with far-ultraviolet light (UV), as assessed by two different methods; estimation of the cloning efficiency of ouabain-resistant (Oua(R)) mutants and detection of K-ras codon 12 mutation in genomic DNA identified by polymerase chain reaction following differential dot blot hybridization. In the present study, F-IFr cells were found to be hypomutable; less than one Oua(R) mutant per 10(4) survival cells after UV (0-12 J/m(2)), in contrast to 0.51-85 Oua(R) mutants per 10(4) survivors in RSa cells, and no detectable K-ras codon 12 mutation at any UV dose tested. However, F-IFr cells, when cultured with medium containing the protease inhibitor antipain immediately and transiently after UV irradiation displayed hypermutability to almost the same extent as RSa cells by both phenotypic and genetic mutation analyses. The refractoriness of F-IFr cells to HuIFN-beta CPI was also suppressed by culture with medium containing antipain during HuIFN-beta exposure. Moreover, F-IFr cells irradiated with UV or treated with HuIFN-beta showed elevation of antipain-sensitive protease activity, but not the irradiated or treated RSa cells. UV- and HuIFN-beta-susceptibility were not modulated by antipain in RSa cells. These antipodal characteristics between the two cell lines suggested that antipain-sensitive proteases and/or cellular functions may be involved in increased resistance of F-IFr cells to both Wand HuIFN-beta refractoriness.
人细胞系F-IFr是一种对人干扰素（HuLFN）-β诱导的细胞增殖抑制（CPI）具有增强抗性的变体，它由对CPI高度敏感的RSa细胞建立而来。最近发现，通过两种不同方法评估，亲本RSa细胞在远紫外线（UV）照射后具有异常高的突变率；通过对哇巴因抗性（Oua(R)）突变体的克隆效率进行估算，以及通过差异点杂交后聚合酶链反应鉴定基因组DNA中的K-ras密码子12突变。在本研究中，发现F-IFr细胞的突变率较低；UV（0-12 J/m²）照射后，每10⁴个存活细胞中Oua(R)突变体少于1个，而RSa细胞中每10⁴个存活细胞中有0.51-85个Oua(R)突变体，并且在任何测试的UV剂量下均未检测到K-ras密码子12突变。然而，F-IFr细胞在UV照射后立即并短暂地在含有蛋白酶抑制剂抗痛素的培养基中培养时，通过表型和基因突变分析显示出与RSa细胞几乎相同程度的高突变率。在HuIFN-β暴露期间，用含有抗痛素的培养基培养也抑制了F-IFr细胞对HuIFN-β CPI的抗性。此外，UV照射或用HuIFN-β处理的F-IFr细胞显示抗痛素敏感蛋白酶活性升高，但UV照射或处理的RSa细胞则未出现这种情况。抗痛素对RSa细胞的UV和HuIFN-β敏感性没有调节作用。这两种细胞系之间的这些相反特征表明，抗痛素敏感蛋白酶和/或细胞功能可能参与了F-IFr细胞对W和HuIFN-β抗性增加的过程。
