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目的观察MDM2在γ射线诱发的小鼠淋巴细胞白血病组织细胞中的表达变化,探讨MDM2在辐射致癌中的作用 及可能的分子机制。方法:用γ射线照射BALB/c小鼠诱发白血病发生,建立辐射致癌动物模型;分别应用Western印迹分析 和原位杂交(ISH)技术,从蛋白水平和mRNA水平检测小鼠胸腺和骨髓组织中MDM2的表达情况;运用免疫沉淀技术检测 MDM2蛋白的磷酸化水平;PCR-SSCP及银染技术用于检测基因突变。结果:癌变组和辐射未癌变组胸腺细胞/骨髓细胞 MDM2蛋白表达水平都高于对照组(P<0.05);而癌变组和辐射未癌变组之间MDM2蛋白水平无明显差异。在γ射线照射后 早期辐射组骨髓MDM2蛋白表达水平也明显高于对照组。ISH结果显示:癌变组织中MDM2阳性反应和阳性率均明显高于 对照组。在癌变组组织中发现有MDM2磷酸化比其他组都明显升高(P<0.05)。辐射组和对照组均未检测到基因突变。结论: MDM2可能参与γ射线诱发的小鼠淋巴细胞白血病的发生和发展过程,作用机制可能与过表达及高磷酸化所致活性增强有 关。MDM2的基因突变在辐射致小鼠白血病发生中不起主要作用。
Objective To investigate the expression of MDM2 in γ-ray-induced mouse lymphoblastic leukemia cells and to explore the role of MDM2 in radiation-induced carcinogenesis and possible molecular mechanisms. Methods: BALB / c mice were induced by γ-ray irradiation to induce leukemia, and the animal model of radiation-induced carcinogenesis was established. Western blotting and in situ hybridization (ISH) were used to detect the expression of MDM2 in mouse thymus and bone marrow The expression of MDM2 protein was detected by immunoprecipitation. PCR-SSCP and silver staining were used to detect the gene mutation. Results: The MDM2 protein expression levels in thymocytes / myeloid cells in cancerous group and non-cancerous group were significantly higher than those in control group (P <0.05). There was no significant difference in MDM2 protein between cancerous group and non-cancerous group. The expression of MDM2 protein in the early radiation group after γ-ray irradiation was also significantly higher than that in the control group. The ISH results showed that the positive rate of MDM2 in cancerous tissues was significantly higher than that of the control group. In the cancerous tissues, MDM2 phosphorylation was found to be significantly higher than other groups (P <0.05). No gene mutation was detected in both radiation group and control group. CONCLUSION: MDM2 may be involved in the occurrence and development of γ-ray-induced mouse lymphoblastic leukemia. The mechanism may be related to the over-expression and hypero-phosphorylation-induced activity. Mutations in MDM2 play no major role in the development of radiation-induced murine leukemia.