EGFR antisense RNA blocks expression of the epidermal growth factor receptor and partially reverse the malignant phenotype of human breast cancer MDA-MB-231 cells

The effects of human EGFR to the malignant phenotype of human breast cancer cell line MDA-MB-231 were investigated experimentally. A retroviral vector containing a 5'1350bp fragment of the human EGFR cDNA in the antisense orientation was transfected into targeted cells by lipofectamine. The effects on cell proliferation, cell cycle and adherent ability to extracellular matrix (ECM) components were studied after the expression of antisense transcripts to EGFR 5'1350bp fragment in target cells. In vitro studies showed that the growth ability of the transfected cells was partialy inhibited in comparison to parental cells and to cells transfected with the plasmid containing the neomycin resistance gene only. It was found that EGF (10ng/ml) had an augmenation effect on the growth of transfected MDA-AS10 cells but not MDA-MB-231 cells.Flow cytometric analysis showed that the cell cycle of the transfected cells was abnormal with a decrease of cells in G2/M and S phases and an increase of cells in G1 phase,indicating a blockage in phase G1. Immunofluorescence of EGFR expression in transfectants stained with an antiEGFR antibody was decreased and their growth in soft agarose was also severely impaired. The transfected cells showed less adherence to laminin (LN) and fibronectin (FN). In short, EGFR antisense RNA decreases the expression of EGFR on MDA-MB-231 cells and partially reverses their malignant phenotype as well.Effects of antisense EGFR on human breast cancer MDA-MB-231 cells

Effect of amlodipine on apoptosis of human breast carcinoma MDA-MB-231 cells

Objective： To elucidate the effects of amlodipine on the proliferation and apoptosis of human breast carcinoma MDA-MB-231 cells. Methods： Light microscopy was used to determine the effects of amlodipine on cell morphology; Flow cytometry was used to quantitate cells undergoing apoptosis; the expression of a cell cycle-related protein, proliferating cell nuclear antigen （PCNA） and an antiapoptosis protein, Bcl-2 were assessed by immunocytochemistry. Results： Amlodipine concentration of 8.25umol/L （1/2 of ICs0） affected the morphology, decreased the expression of PCNA and Bcl-2 and induced apoptosis of human breast carcinoma MDA-MB-231 cells. Conclusion： The effect of amlodipine on the antiproliferation of human breast carcinoma MDA-MB-231 cells is related to inducement of apoptosis, and the decrease of the expression of Bcl-2 and PCNA may be the possible mechanism for proliferation inhibitory and inducement of apoptosis.

miR-9-5p对乳腺癌恶性生物学行为的影响及其调控机制

目的:探讨miR-9-5p在乳腺癌恶性生物学行为中发挥的作用及其可能的调控机制。方法:利用OncomiR在线数据库分析miR-9-5p在乳腺癌组织与正常乳腺组织中表达的差异,qPCR检测乳腺癌细胞系与正常乳腺细胞中miR-9-5p表达水平。基于靶基因预测软件TargetScan分析ONECUT2(one cut homeobox 2)可能是miR-9-5p的作用靶基因,双荧光素酶报告实验验证两者的靶向关系。向MDA-231细胞中分别转染miR-9-5p mimic、ONECUT2 siRNA及相应对照,qPCR及WB实验检测转染对MDA-231细胞中干性基因NOTCH1、NANOG和Y染色体性别决定区(sex-determing region of Y chromosome,SRY)-盒转录因子9(SRY-box transcription factor 9,SOX9)表达水平的影响,BrdU法、AnnexinⅤ流式细胞术、MTS实验分别检测转染对细胞增殖、凋亡和化疗耐药的影响,ALDEFLUOR染色流式细胞术检测miR-9-5p及靶基因ONECUT2对肿瘤干细胞化特征的影响。建立NSG小鼠乳腺癌化疗模型,体内实验进一步验证ONECUT2对肿瘤干性化及化疗抵抗等肿瘤恶性生物学行为的影响。结果:miR-9-5p在乳腺癌组织(P=0.007)及乳腺癌MDA-231细胞系(P=0.0005)中呈现显著高表达,并与乳腺癌患者不良预后呈正相关(P=0.0016)。miR-9-5p可靶向负调控ONECUT2,进而增加ALDH+MDA-231细胞比例(P=0.0006),上调干性NOTCH1、NANOG和SOX9蛋白表达,并增强乳腺癌细胞抗凋亡能力(P=0.0003)及其对多西他赛(DTX)和多柔比星(DOXO)化疗的耐受性;然而miR-9-5p/ONECUT2轴未能显著影响MDA-231细胞的增殖能力(P>0.05)。与对照组相比,MDA-231/ONECUT2组小鼠接受DTX治疗后,移植瘤体积较对照组显著缩小(P<0.05),瘤组织中NOTCH1、SOX9蛋白和ABC转运蛋白的mRNA和蛋白表达水平均显著降低(P<0.05或P<0.01)。结论:乳腺癌组织中高表达的miR-9-5p通过靶向ONECUT2诱导乳腺癌干细胞化及抗凋亡能力,增强了其对化学治疗的抵抗性。

MicroRNA-21 targets tumor suppressor genes in invasion and metastasis

MicroRNAs （miRNAs） are a class of naturally occurring small non-coding RNAs that target protein-coding mRNAs at the post-transcriptional level. Our previous studies suggest that mir-21 functions as an oncogene and has a role in tumorigenesis, in part through regulation of the tumor suppressor gene tropomyosin 1 （TPM1）. Given that TPM1 has been implicated in cell migration, in this study we further investigated the role of mir-21 in cell invasion and tumor metastasis. We found that suppression of mir-21 in metastatic breast cancer MDA-MB-231 cells significantly reduced invasion and lung metastasis. Consistent with this, ectopic expression of TPM1 remarkably reduced cell invasion. Furthermore, we identified two additional direct mir-21 targets, programmed cell death 4 （PDCD4） and maspin, both of which have been implicated in invasion and metastasis. Like TPM1, PDCD4 and maspin also reduced invasiveness of MDA-MB-231 cells. Finally, the expression of PDCD4 and maspin inversely correlated with mir-21 expression in human breast tumor specimens, indicating the potential regulation of PDCD4 and maspin by mir-21 in these tumors. Taken together, the results suggest that, as an oncogenic miRNA, mir-21 has a role not only in tumor growth but also in invasion and tumor metastasis by targeting multiple tumor/metastasis suppressor genes. Therefore, suppression of mir-21 may provide a novel approach for the treatment of advanced cancers.