中文摘要：

目的：观察RNA干扰（RNAi）下调HER-2受体后乳腺癌细胞及其移植肿瘤对化疗药物表柔比星（epirubicin,EPI）敏感性的变化。方法：构建能够表达HER-2siRNA的质粒载体HER-2shRNApU6,转染HER-2阳性的乳腺癌细胞SK-BR-3,RT-PCR与Western blotting检测SKBR-3细胞HER-2mRNA与蛋白的表达。受转染细胞与不同浓度的化疗药物表柔比星共培养,MTT法检测细胞增殖活性及药物IC50 构建裸鼠乳腺癌模型,观察经HER-2shRNApU6治疗后,肿瘤对化疗的敏感性。结果：SKBR-3细胞转染HER-2shRNApU6后,HER-2mRNA及蛋白表达出现明显下调,细胞增殖活性出现明显下降（P〈0.05）,治疗组肿瘤细胞对表柔比星的化疗敏感性IC50为0.25μg/μl,而阴性对照及空白对照分别为3.46μg/μl和3.69μg/μl。裸鼠移植肿瘤模型中,治疗组肿瘤重量明显低于空白对照和阴性对照[（2.17±0.58）vs（3.13±0.38）、（3.21±0.89）g]。结论：HER-2的RNA干扰显著抑制乳腺癌SKBR-3细胞mRNA和蛋白表达,从而明显提高肿瘤细胞及其种植瘤对表柔比星的敏感性。

英文摘要：

Objective： To observe the sensitivities of breast cancer cells and its implanted tumors to chemotherapeutic drug epirubicin after down-regulation of HER-2 expression by RNA interference （RNAi）. Methods： HER-2siRNApU6 vector containing HER-2 RNAi was constructed and was used to transfect HER-2 positive breast cancer cell line SKBR-3. The expression of HER-2 mRNA and protein were analyzed by RT-PCR and Western blotting, respectively. Transfected SKBR-3 cells were treated with different concentrations of epirubicin; the growth of SKBR-3 cells and IC50 of epirubicin were observed by MTY. SKBR-3 cells were injected into nude mouse to establish breast cancer model; the sensitivity of mouse model to epirubicin was observed after HER-2shRNApU6 treatment. Results： Expression of HER-2 mRNA and HER-2 protein were down-regulated in SKBR-3 cells after transfection with HER-2shRNApU6. Furthermore, the prolifera- tion of SKBR-3 cells transfected with HER-2shRNApU6 was significantly decreased compared with mock tansfected group （P 〈 O. 05）. Chemo-sensitivity of SKBR-3 cells to epirubicin was enhanced after treatment with HER-2shRNApU6, with the ICs0 values of HER-2shRNApU6, mock, and negative tansfected group being 0.25, 3.46 and 3.69 μg/μl, respectively. The tumor weight was significantly lower in HER-2shRNApU6 group than those in the mock and negative control group [ （2.17 ±0.58）vs （3.13 ±0.38）, （3.21 ±0.89）g]. Conclusion： HER-2 RNAi obviously inhibits the expression of HER-2 mRNA and HER-2 protein in SKBR-3 breast cancer cells, thus increases their sensitivities to epirubicin in vitro and in vivo.