Whong W Z, Gao H G, Zhou G, Ong T
Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505-2888, USA.
J Toxicol Environ Health A. 1999 Mar 26;56(6):397-404. doi: 10.1080/009841099157980.
Our previous studies have shown that glass fibers induced morphological transformation in BALB/c-3T3 cells and that transformed cells possessed preneoplastic properties and transforming genes. In the current study, possible molecular mechanisms of glass fiber-induced cell transformation related to the activation and/or inactivation of cancer-related genes resulting from gene amplification and/or point mutations were investigated. Gene amplification was determined by Southern blot analysis of K-ras, H-ras, c-myc, and c-fos proto-oncogenes. Mutational spectra of the p53 tumor suppressor gene and the K-ras proto-oncogene were characterized by single-stranded conformation polymorphism and DNA sequencing. Southern blot analysis showed that gene amplification was found in 56% (K-ras and c-myc), 67% (c-fos), and 100% (H-ras) of glass fiber-transformed cell lines. DNA sequencing analysis revealed that both transition and transversion mutations occurred and were concentrated in exon 2 of K-ras and exon 4 of p53. In addition, multiple mutations in different codons were found in K-ras and p53 These results suggest that (1) glass fiber-induced cell transformation could be attributed to the activation of the H-ras, K-ras, c-myc, and c-fos proto-oncogenes and/or the inactivation of the p53 tumor suppressor gene by gene amplification and/or point mutations and (2) multiple mutations might be due to genomic instability resulting from chromosomal alterations induced by glass fibers.
我们之前的研究表明，玻璃纤维可诱导BALB/c-3T3细胞发生形态转化，且转化后的细胞具有肿瘤前体特性和转化基因。在本研究中，我们探究了玻璃纤维诱导细胞转化的可能分子机制，这些机制与因基因扩增和/或点突变导致的癌症相关基因的激活和/或失活有关。通过对K-ras、H-ras、c-myc和c-fos原癌基因进行Southern印迹分析来确定基因扩增情况。通过单链构象多态性和DNA测序来表征p53肿瘤抑制基因和K-ras原癌基因的突变谱。Southern印迹分析表明，在56%（K-ras和c-myc）、67%（c-fos）和100%（H-ras）的玻璃纤维转化细胞系中发现了基因扩增。DNA测序分析显示，转换和颠换突变均有发生，且集中在K-ras的第2外显子和p53的第4外显子。此外，在K-ras和p53中发现了不同密码子的多个突变。这些结果表明：（1）玻璃纤维诱导的细胞转化可能归因于H-ras、K-ras、c-myc和c-fos原癌基因的激活和/或p53肿瘤抑制基因因基因扩增和/或点突变而失活；（2）多个突变可能是由于玻璃纤维诱导的染色体改变导致基因组不稳定所致。
