Mechanism(s) of Leukemogenesis in Genetically-Altered Mouse Models

基因改造小鼠模型中白血病发生的机制

• 批准号: 6432229
• 负责人: JOHN EDGAR FRENCH
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6432229
• 关键词: animal genetic material tag; benzene; carcinogen testing; chemical carcinogen; chemical carcinogenesis; genetically modified animals; laboratory mouse; leukemia; mutagen testing; mutagens; neoplasm /cancer genetics

Leukemia incidence is increasing, especially in children, and the contribution of ubiquitous exposure to environmental leukemogens is unknown. Since mutated ras oncogene is the most frequent abnormality reported in myelodysplastic syndromes and acute myeloid leukemias in humans, we chose to use the z-globin promoted v-Ha-ras Tg.AC transgenic line to investigate the role of an inducible oncogenic ras in the induction of leukemia after exposure to benzene (BZ). Here we describe the morphological and immunophenotypic analysis as well as a spleen colony assay data, to demonstrate that repeated dermal exposure of Tg.AC mice to BZ, but not the nontransgenic parent strain FVB/N, induced a myelogenous leukemia. Profound anemia and marked neutrophilia with presence of a left shift, marked increase in the number of progenitors that differentiated to granulocytes in bone marrow, and infiltration of hematopoietic tissues by myeloid cells characterized the BZ-induced disease. Transformation of a hematopoietic cell was confirmed by transplantation experiments to isogenic, irradiated FVB/N recipients. The absence of symptoms in untreated Tg.AC, as in nontransgenic parent strain, indicated a role for the v-Ha-ras transgene message in the development of BZ-induced myelogenous leukemia. We propose that BZ-induction of the transgene occurred in a bone marrow (BM) progenitor directed toward the granulocytic lineage. By in situ hybridization (ISH) analysis, reverse transcription polymerase chain reaction (RT-PCR) assay and immunohistochemistry staining, here we demonstrated that only leukemic recipient spleen and leukemic donor spleen and liver expressed the inducible ras transgene message concomitant to mitotic activity of hematopoietic blasts. Contrary to control, none of the BZ-treated Tg.AC BM cells expressed the transgene message, possibly due to BZ metabolite toxicity for progenitors. However, recipient mice injected with normal Tg.AC BM cells that express the transgene message did not develop leukemia, suggesting that cell transformation required other mutation(s). Finally, a ribonuclease protection analysis (RPA) demonstrated that the alteration of cytokines in BZ-treated BM could promote the survival of a transformed cell. We hypothesize that the combination of v-Ha-ras activation in a progenitor and the alteration of the cytokines in BM were permissive for a clone of transformed cell to acquire new mutation(s) and the myelogenous leukemia to develop from MPD. - benzene, cancer, leukemia, transgenic, loss of heterozygosity, p53, tumor suppressor gene, ras, protooncogene

白血病发病率正在增加，特别是在儿童中，而普遍暴露于环境致白血病原的影响尚不清楚。由于突变的 ras 癌基因是人类骨髓增生异常综合征和急性髓系白血病中最常见的异常，因此我们选择使用 z-球蛋白促进的 v-Ha-ras Tg.AC 转基因系来研究可诱导致癌 ras 在接触苯 (BZ) 后诱发白血病中的作用。在这里，我们描述了形态学和免疫表型分析以及脾集落测定数据，以证明 Tg.AC 小鼠反复皮肤暴露于 BZ，而不是非转基因亲本菌株 FVB/N，诱导了骨髓性白血病。严重贫血和明显的中性粒细胞增多并伴有左移、骨髓中分化为粒细胞的祖细胞数量显着增加以及骨髓细胞浸润造血组织是 BZ 诱导疾病的特征。通过对等基因、受辐射的 FVB/N 受体的移植实验证实了造血细胞的转化。与非转基因亲本菌株一样，未经处理的 Tg.AC 中没有症状，表明 v-Ha-ras 转基因信息在 BZ 诱导的骨髓性白血病的发展中发挥作用。我们提出转基因的 BZ 诱导发生在针对粒细胞谱系的骨髓 (BM) 祖细胞中。通过原位杂交（ISH）分析、逆转录聚合酶链反应（RT-PCR）分析和免疫组织化学染色，我们证明只有白血病受体脾脏和白血病供体脾脏和肝脏表达伴随造血母细胞有丝分裂活性的诱导型ras转基因信息。与对照相反，BZ 处理的 Tg.AC BM 细胞均不表达转基因信息，这可能是由于 BZ 代谢物对祖细胞的毒性。然而，注射了表达转基因信息的正常 Tg.AC BM 细胞的受体小鼠并未患上白血病，这表明细胞转化需要其他突变。最后，核糖核酸酶保护分析 (RPA) 表明，BZ 处理的 BM 中细胞因子的改变可以促进转化细胞的存活。我们假设祖细胞中 v-Ha-ras 的激活和 BM 中细胞因子的改变相结合，使得转化细胞的克隆获得新的突变，并允许从 MPD 发展为骨髓性白血病。 - 苯、癌症、白血病、转基因、杂合性缺失、p53、抑癌基因、ras、原癌基因