目的:研究miR-342-3p对乳腺癌化疗敏感性的影响。方法:检测乳腺癌细胞株MCF-7、SKBr3和MDA-MB-231中miR-342-3p的表达。应用脂质体转染方法,转染hsa-miR-342-3p模拟物到低表达miR-342-3p的乳腺癌细胞株(mimic转染组),同时设立阴性对照(mim-NC转染组);转染miR-342-3p抑制物到高表达miR-342-3p的乳腺癌细胞株(inhibitor转染组),同时设立阴性对照(inhi-NC转染组)。mimic转染组、mim-NC转染组、inhibitor转染组和inhi-NC转染组细胞,分别加入浓度为2μmol/L的紫杉醇、顺铂及4μmol/L的阿霉素的进行培养,应用CCK8法检测药物作用48 h后细胞增殖率的变化。结果:以SKBr3为参照,miR-243-3p在MCF-7细胞中的相对表达倍数是126.000,在MDA-MB-231细胞中的相对表达倍数是0.017。mimic转染组细胞与紫杉醇、顺铂孵育48 h后,肿瘤细胞增殖率低于mim-NC转染组,差异有统计学意义(P<0.05),但与阿霉素孵育后细胞增殖率与mim-NC转染组差异无统计学意义(P>0.05);inhibitor转染组细胞与紫杉醇、顺铂和阿霉素孵育48 h后,肿瘤细胞的增殖率高于inhi-NC转染组,差异有统计学意义(P<0.05)。结论:miR-342-3p能调控乳腺癌细胞株MDA-MB-231、MCF-7对紫杉醇和顺铂的化疗敏感性,但提高miR-342-3p表达不能增加MDA-MB-231细胞对阿霉素的化疗敏感性,降低miR-342-3p的表达却可以减弱MCF-7细胞对阿霉素的化疗敏感性。 Objective: To study the effect of miR-342-3p on the chemosensitivity of breast cancer. Methods: The expression of miR-342-3p in breast cancer cell lines MCF-7, SKBr3 and MDA-MB-231 was detected. The transfected hsa-miR-342-3p mimics were transfected into the miR-342-3p-expressing breast cancer cell line (mimic transfection group) by liposome transfection method. At the same time, a negative control (mim-NC transfection group ). The miR-342-3p inhibitor was transfected into the breast cancer cell line with high expression of miR-342-3p and a negative control (inhi-NC transfected group) was established. mimic transfection group, mim-NC transfection group, inhibitor transfection group and inhi-NC transfection group were cultured with paclitaxel, cisplatin and 4μmol / L doxorubicin at a concentration of 2μmol / L, respectively The CCK8 assay was used to detect the change of cell proliferation after 48 h treatment. Results: The relative expression fold of miR-243-3p in MCF-7 cells was 126.000 and the relative expression fold was 0.017 in MDA-MB-231 cells. After being incubated with paclitaxel and cisplatin for 48 h, the proliferation rate of tumor cells in mimic-transfected group was lower than that in mim-NC transfected group (P <0.05) There was no significant difference in the mim-NC transfection group (P> 0.05). After 48 h of incubation with paclitaxel, cisplatin and doxorubicin, the proliferation rate of tumor cells in inhibitor transfected group was higher than inhi-NC transfected group, The difference was statistically significant (P <0.05). Conclusion: miR-342-3p can modulate the chemosensitivity of breast cancer cell lines MDA-MB-231 and MCF-7 to paclitaxel and cisplatin. However, the up-regulation of miR-342-3p can not increase the sensitivity of MDA-MB- Chemotherapeutic sensitivity of moxins to miR-342-3p decreased chemosensitivity to doxorubicin in MCF-7 cells.