QUANTITATIVE STUDIES ON CONCURRENT FACTORS IN NEOPLASTIC TRANSFORMATION

摄取、细胞毒性、肿瘤转化和癌基因表达， 由结晶二氧化硅样品（直径<5微米）引起的 在BALB/3 T3/A31-1-1小鼠胚胎细胞系中研究。 微粒， 进一步表征了表面性质和尺寸，包括几个 石英、方石英和鳞石英样品以及非纤维化粉尘 以供比较。 采用连续定时的方法研究了细胞的摄取和细胞毒性。 相衬摄影，并通过扫描和传输 电子显微镜（E.M.）。 细胞单层，先前暴露于二氧化硅 或未暴露，在2周时接受一剂二氧化硅：细胞溶解 生长缓慢，在3-4天达到高峰，随后汇合的再生 10天的单层;在先前未治疗的 和二氧化硅预处理的细胞，表明二氧化硅毒性没有 导致抗性细胞的选择。 E.M.研究表明， 二氧化硅颗粒，有时被伪足吞噬， 主要在膜结合囊泡中;细胞质细胞器的破坏 是在一些粒子周围发现的 发现了一些微粒 与核膜;很少有在细胞核内。 重复 转化测定显示转化的剂量依赖性诱导， 病灶高达25-50 μ g/cm 2的剂量，随后是指示 可能与摄取有关的限速因素。 石英样品F600， 显示出最小的细胞毒性，但相同水平的转化活性， 与其他有毒石英样品一样。 所有转化灶均由 测试的石英样品在裸鼠中迅速致瘤。 核型 对9个二氧化硅转化的细胞系（每个细胞系7-8个中期分裂相）的分析显示， 所有的人都获得了一个或多个标记染色体，这在未经治疗的人中是看不到的。 细胞或自发转化体中。 从硅胶中分离的总RNA 诱导的病灶，通过用10个探针的狭缝印迹杂交分析， 不同的癌基因和p53，显示myc，H- 在MQZ和HFMQZ转化的细胞中， F600 这些基因的表达进一步增加， 裸鼠中的相应肿瘤。

Uptake, cytotoxicity, neoplastic transformation and oncogene expression, induced by samples of crystalline silica (<5 microns in diameter) were studied in the BALB/3T3/A31-1-1 mouse embryo cell line. Particulates, further characterized for surface properties and size, included several samples of quartz, cristobalite and tridymite, and non-fibrogenic dusts for comparison. Uptake and cytotoxicity were studied by serially timed phase-contrast photography, and by scanning and transmission electronmicroscopy (E.M.). Cell monolayers, previously exposed to silica or unexposed, received a dose of silica at 2 weeks: cell lysis developed slowly and peaked at 3-4 days, followed by regrowth of confluent monolayers by 10 days; the response was the same in previously untreated and silica-pretreated cells, indicating that silica toxicity did not result in selection of resistant cells. E.M. studies showed uptake of silica particles, sometimes engulfed by pseudopodia, and internalized mostly in membrane-bound vesicles; destruction of cytoplasmic organelles was found around some particles. Some particles were found in contact with the nuclear membrane; very few were inside nuclei. Repeated transformation assays showed a dose dependent induction of transformed foci up to a dose of 25-50 microg/cm2, followed by a plateau indicative of a rate-limiting factor possibly related to uptake. A quartz sample, F600, showed minimal cytotoxicity, but the same level of transforming activity as other more toxic quartz samples. All the transformed foci induced by tested quartz samples were rapidly tumorigenic in nude mice. Karyotypic analysis of 9 silica-transformed cell lines (7-8 metaphases each) showed that all had acquired one or more marker chromosomes not seen in untreated cells or in spontaneous transformants. Total RNA isolated from silica- induced foci, analyzed by slot blot hybridization with 10 probes for different oncogenes and for p53, showed increased expression of myc, H- ras, K-ras, abl and p53 in cells transformed by MQZ and HFMQZ, but not by F600. Expression of these genes was further increased in the corresponding tumors in nude mice.