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目的：抑制细胞内的Ｏ６－甲基鸟嘌呤－ＤＮＡ甲基转移酶（ＭＧＭＴ）基因表达水平，逆转肿瘤细胞对嘧啶亚硝脲的耐药性。方法：本实验构建了三个表达ＭＧＭＴ反义ＲＮＡ的逆转录病毒载体（ｐＬＭＴＳＮＡＳ，ｐＬＭ５ＳＮＡＳ和ｐＬＭ３ＳＮＡＳ），并用它们转导ＨｅＬａＳ３肿瘤细胞，观察细胞在转导前后ＭＧＭＴ基因表达水平及其对嘧啶亚硝脲（ＡＣＮＵ）抗药性的变化。结果：研究发现针对ＭＧＭＴｍＲＮＡ５端的反义ＲＮＡ能够有效地降低ＨｅＬａＳ３细胞的ＭＧＭＴ基因表达水平（为对照细胞的３０％～４０％），并使细胞对ＡＣＮＵ的敏感性提高４．６倍；针对ＭＧＭＴｍＲＮＡ全长的反义ＲＮＡ，也能在一定程度上调节细胞的ＭＧＭＴ基因表达水平并增加细胞对ＡＣＮＵ的敏感性，而针对３端序列的反义ＲＮＡ对ＭＧＭＴ基因无调节作用。转导细胞对ＡＣＮＵ耐药性的变化与ＭＧＭＴ基因表达水平的抑制程度密切相关。结论：合适的反义ＲＮＡ能够有效地调节ＭＧＭＴ基因表达水平，克服肿瘤细胞对ＡＣＮＵ的耐药性
Objective: To inhibit the expression of O6-methylguanine-DNA methyltransferase (MGMT) gene in cells and reverse the resistance of tumor cells to pyrimidine nitrosourea. METHODS: Three retroviral vectors expressing MGMT antisense RNA (pLMTSNAS, pLM5SNAS and pLM3SNAS) were constructed and used to transduce HeLaS3 tumor cells. The expression level of MGMT and its effect on nitrosamines before and after transduction were observed. Changes in urea (ACNU) resistance. Results: The study found that the antisense RNA targeting MGMT mRNA could effectively reduce the MGMT gene expression level of HeLaS3 cells (30% to 40% of control cells), and increase the sensitivity of cells to ACNU by 4.6 times; against MGMT mRNA. The full-length antisense RNA can also regulate the MGMT gene expression level of the cells to a certain extent and increase the sensitivity of the cells to ACNU, while the antisense RNA targeting the 3′-end sequence has no regulatory effect on the MGMT gene. The change in ACNU resistance of transduced cells is closely related to the degree of inhibition of MGMT gene expression levels. Conclusion: The appropriate antisense RNA can effectively regulate the expression of MGMT gene and overcome the resistance of tumor cells to ACNU.