Knockdown of c-Myc expression by RNAi inhibits MCF-7 breast tumor cells growth in vitro and in vivo

IntroductionBreast cancer is the leading cause of cancer death in women worldwide. Elevated expression of c-Myc is a frequent genetic abnormality seen in this malignancy. For a better understanding of its role in maintaining the malignant phenotype, we used RNA interference (RNAi) directed against c-Myc in our study. RNAi provides a new, reliable method to investigate gene function and has the potential for gene therapy. The aim of the study was to examine the anti-tumor effects elicited by a decrease in the protein level of c-Myc by RNAi and its possible mechanism of effects in MCF-7 cells.MethodA plasmid-based polymerase III promoter system was used to deliver and express short interfering RNA (siRNA) targeting c-myc to reduce its expression in MCF-7 cells. Western blot analysis was used to measure the protein level of c-Myc. We assessed the effects of c-Myc silencing on tumor growth by a growth curve, by soft agar assay and by nude mice experiments in vivo. Standard fluorescence-activated cell sorter analysis and TdT-mediated dUTP nick end labelling assay were used to determine apoptosis of the cells.ResultsOur data showed that plasmids expressing siRNA against c-myc markedly and durably reduced its expression in MCF-7 cells by up to 80%, decreased the growth rate of MCF-7 cells, inhibited colony formation in soft agar and significantly reduced tumor growth in nude mice. We also found that depletion of c-Myc in this manner promoted apoptosis of MCF-7 cells upon serum withdrawal.Conclusionc-Myc has a pivotal function in the development of breast cancer. Our data show that decreasing the c-Myc protein level in MCF-7 cells by RNAi could significantly inhibit tumor growth both in vitro and in vivo, and imply the therapeutic potential of RNAi on the treatment of breast cancer by targeting overexpression oncogenes such as c-myc, and c-myc might be a potential therapeutic target for human breast cancer.     

Expression of survivin and E-cadherin in breast cancer

Survivin is a member of the inhibitor of apoptosis (IAP) family, and is involved in the regulation of cell division. Survivin expression is related with poor survival of patients with tumors including neuroblastoma, non-small-cell lung cancer, breast carcinoma, gastric carcinoma, rectal cancer, recurrent ????????????colorectal carcinoma and bladder cancer. It is thought to be an important prognostic marker in cancers[1,2]. E-cadherin functionally belongs to transmembrane glycoproteins family,…     

Glycodelin reduces breast cancer xenograft growth in vivo

Malignant growth is characterized by loss of cell differentiation, uncontrolled proliferation and resistance to apoptosis. Many tumor suppressor genes that protect cells against malignant transformation regulate cell differentiation. Here, we show for the first time that glycodelin, a differentiation-related protein, reduces breast cancer tumor growth in vivo. We found that glycodelin cDNA-transfected MCF-7 breast cancer cells showed a differentiated phenotype and produced smaller tumors in mouse mammary fat pads compared with control-transfected cells. Glycodelin-induced differentiation was associated with reduced expression of oncogenes and increased expression of tumor suppressor genes. Our results suggest that glycodelin acts as a tumor suppressor in breast cancer. This may explain its reported association with a more favorable prognosis in some cancers.     

三苯氧胺诱导人乳腺癌MCF-7细胞株耐药及自噬的关系研究

背景与目的:三苯氧胺(tamoxifen)作为第一代选择性雌激素受体调节剂(selective estrogen receptor modulator,SERM)被广泛地应用于激素敏感型乳腺癌的内分泌一线治疗。三苯氧胺耐药的发生严重限制了临床治疗,是乳腺癌患者用药面临的重大难题,明确其耐药机制对乳腺癌的治疗有重要临床意义。本研究通过体外诱导人乳腺癌细胞MCF-7三苯氧胺耐药,探讨细胞产生三苯氧胺耐药时自噬水平的变化与MAPK家族蛋白细胞外信号调节激酶(extracellular signal-regulated kinase,ERK)蛋白表达量及磷酸化水平的变化。方法:浓度递增筛选法诱导MCF-7细胞耐药,透射电镜观察MCF-7细胞与耐药细胞内的自噬泡数量,CCK8法检测细胞增殖状态,应用Western blot检测LC3Ⅱ、ERK1/2、Phospho-ERK1/2蛋白的表达情况。结果:诱导的三苯氧胺耐药细胞株TR5达到5μmol/L的耐药浓度。TR5细胞内的自噬泡数量与LC3Ⅱ表达量明显高于MCF-7细胞。ERK蛋白在两种细胞中的表达量差异无统计学意义,但其在TR5中的磷酸化水平比MCF-7细胞高。结论:...     

不同化疗方案对MCF-7乳腺癌荷瘤裸鼠的抑瘤作用及对PCNA表达的影响

背景与目的：随着规范化化疗在临床推广，化疗疗效正稳步提高，但仍无法实现真正意义上的个体化化疗。本研究通过研究不同化疗方案对乳腺癌荷瘤裸鼠的抑瘤作用及瘤组织中增殖细胞核抗原（PCNA）表达的影响，探讨PCNA在评价乳腺癌化疗效果及选择化疗方案的意义。方法：①制备MCF-7细胞系移植性乳腺癌裸鼠模型；②不同化疗方案化疗后监测裸鼠体重和肿瘤体积的变化情况，计算抑瘤率；③观察肿瘤病理组织学变化，并用免疫组化和流式细胞术检测PCNA表达情况。结果：①荷瘤裸鼠体重、瘤重和抑瘤率：2／3LD10剂量各化疗组裸鼠体重和瘤重均显著低于对照组（P〈0．05），抑瘤率分别为83．1％、75。5％、84。6％、87．9％、91．0％。提示2／3LD10剂量化疗组可较准确反应化疗药物的联合作用和对裸鼠的影响，故选择2／3LD10剂量化疗组进入后续的研究。②PCNA表达：免疫组化：各化疗组PCNA表达均显著低于对照组（P〈0．05），且NP组显著低于CMF、CAF、TP和Xeloda组（P〈0．05），TP、Xeloda组显著低于CMF、CAF组（P〈0．05）；流式细胞术：各化疗组PCNA表达较对照组显著下降（P〈0．05），且TP和Xeloda组显著低于cMF、CAF组（P〈0．05），NP组显著低于cMF组（P〈0．05）。③PCNA表达与病理学疗效分级呈显著正相关（r=0．540，P〈0．05）。结论：联合化疗对荷瘤裸鼠的抑瘤作用明显，并可降低乳腺癌组织中的PCNA表达；PCNA表达水平可作为判断乳腺癌化疗效果的评价指标，且可为临床制定方案提供参考。     

Human UDP-Glucuronosyltransferases: Effects of altered expression in breast and pancreatic cancer cell lines

Increased aerobic glycolysis and de novo lipid biosynthesis are common characteristics of invasive cancers. UDP-glucuronosyltransferases (UGTs) are phase II drug metabolizing enzymes that in normal cells possess the ability to glucuronidate these lipids and speed their excretion; however, de-regulation of these enzymes in cancer cells can lead to an accumulation of bioactive lipids, which further fuels cancer progression. We hypothesize that UGT2B isoform expression is down-regulated in cancer cells and that exogenous re-introduction of these enzymes will reduce lipid content, change the cellular phenotype, and inhibit cancer cell proliferation. In this study, steady-state mRNA levels of UGT isoforms from the 2B family were measured using qPCR in 4 breast cancer and 5 pancreatic cancer cell lines. Expression plasmids for UGT2B isoforms known to glucuronidate cellular lipids, UGT2B4, 2B7, and 2B15 were transfected into MCF-7 and Panc-1 cells, and the cytotoxic effects of these enzymes were analyzed using trypan blue exclusion, annexin V/PI staining, TUNEL assays, and caspase-3 immunohistochemistry. There was a significant decrease in cell proliferation and a significant increase in the number of dead cells after transfection with each of the 3 UGT isoforms in both cell lines. Cellular lipids were also found to be significantly decreased after transfection. The results presented here support our hypothesis and emphasize the important role UGTs can play in cellular proliferation and lipid homeostasis. Evaluating the effect of UGT expression on the lipid levels in cancer cell lines can be relevant to understanding the complex regulation of cancer cells, identifying the roles of UGTs as “lipid-controllers” in cellular homeostasis, and illustrating their suitability as targets for future clinical therapy development.     

葫芦素B在体内外对乳腺癌细胞的生长抑制作用

目的:体内外观察葫芦素B(cucurbitacin B)对人乳腺癌细胞系MCF-7的增殖抑制和诱导凋亡作用,为临床应用提供依据.方法:用浓度分别为0.001、0.01、0.1、1、10以及100μmoL/L的葫芦素B处理MCF-7细胞,24、48和72 h后用MTT法检测细胞增殖.用O.1和10μmol/L的葫芦素B处理MCF-7细胞24h,之后用流式细胞仪检测细胞周期分布和细胞凋亡率,并用倒置显微镜和荧光显微镜观察细胞凋亡.建立乳腺癌裸鼠移植瘤模型,观察葫芦素B的体内抑瘤作用.结果:MTT结果显示葫芦素B对MCF-7细胞的增殖抑制作用具有明显的剂量和时间依赖性.流式细胞仪检测提示,随着葫芦素B浓度增高,处于S期和G2/M期细胞的比例逐渐升高,同时伴随G0/G1期细胞的减少以及细胞凋亡率的逐渐升高.统计学分析提示,各实验组之间以及实验组与对照组之间均有显著差异(P相似文献   

不同化疗方案对裸鼠MCF-7乳腺癌移植瘤PCNA和Bcl-2表达的影响

目的：研究不同化疗方案对乳腺癌组织PCNA和Bcl-2的影响,探讨二者与化疗的关系及评价疗效的价值。方法：制备MCF-7乳腺癌荷瘤裸鼠模型,化疗后观察移植瘤病理组织学疗效,用免疫组化SP法显示乳腺癌组织PCNA和Bcl-2表达情况。结果：（1）各化疗组瘤组织PCNA表达显著低于对照组（P〈0．05）,且NP、TP和Xeloda组显著低于CMF、CAF组（P〈0．05）。PCNA表达与病理疗效显著相关（P=0．001）。（2）CAF、NP、TP和Xeloda化疗组Bcl-2蛋白表达显著高于对照组（P〈0．05）,且TP组显著高于CMF、CAF组（P〈0．05）。Bcl-2表达与病理疗效无显著相关性（P=0．093）。结论：化疗可降低乳腺癌组织PCNA表达,并增强Bcl-2的表达,且不同化疗方案对二者影响的差异有显著性。PCNA可作为评价乳腺癌化疗效果的参考指标,对选择化疗方案可能有指导意义。     

Targeting highly expressed extracellular HSP90 in breast cancer stem cells inhibits tumor growth in vitro and in vivo

Breast cancer stem cells (BCSC) have been identified in breast carcinoma as CD44⁺/CD24^?/low cells, which display tumorigenic activity and have the ability to self-renew, differentiate and metastasize. Previous studies showed that extracellular HSP90 (eHSP90) participates in the invasion and metastatic processes of various cancers including breast cancer. Here, we show for the first time that eHSP90 is over-expressed in mammosphere cultures that are derived from the MDA-MB-231, MDA-MB-453 and MCF-7 breast cancer cell lines. These mammospheres are highly enriched in cells of the CD44⁺/CD24^?/low BCSC phenotype and additionally show high expression of the BCSC markers CD49f and Sox2. Thus our results indicate that eHSP90 represents a potential novel BCSC marker. Moreover, we present evidence that eHSP90 is functionally involved in BCSC activity in vitro and in vivo. Selective neutralization of eHSP90, using the monoclonal antibody mAb 4C5, has the capacity to inhibit stem cell activity in vitro because the formation of mammosphere-derived colonies is dramatically reduced in its presence. In vivo, the treatment of mice with mAb4C5 using a prophylactic protocol, significantly inhibited the primary growth of MDA-MB-231 and mammosphere-derived tumors. More importantly, administration of this antibody in a therapeutic protocol caused a statistically significant regression of established tumors derived from MDA-MB-231 originating mammospheres. Tumor regression was even greater when mAb 4C5 was administered in combination with paclitaxel. Overall, our findings implicate eHSP90 as a potential novel BCSC biomarker. Moreover they show that eHSP90 participates in BCSC-derived primary tumor growth. Finally, we provide additional support for the possible therapeutic value of mAb4C5 in the treatment of breast cancer.     

Melatonin inhibits aromatase promoter expression by regulating cyclooxygenases expression and activity in breast cancer cells

Background:

Melatonin reduces the development of breast cancer interfering with oestrogen-signalling pathways, and also inhibits aromatase activity and expression. Our objective was to study the promoters through which melatonin modifies aromatase expression, evaluate the ability of melatonin to regulate cyclooxygenases and assess whether the effects of melatonin are related to its effects on intracellular cAMP, in MCF-7 cells.

Methods:

Total aromatase mRNA, aromatase mRNA promoter regions and cyclooxygenases mRNA expression were determined by real-time RT–PCR. PGE₂ and cAMP were measured by kits.

Results:

Melatonin downregulated the gene expression of the two major specific aromatase promoter regions, pII and pI.3, and also that of the aromatase promoter region pI.4. Melatonin 1 nM was able to counteract the stimulatory effect of tetradecanoyl phorbol acetate on PGE₂ production and inhibit COX-2 and COX-1 mRNA expression. Melatonin 1 nM elicited a parallel time-dependent decrease in both cyclic AMP formation and aromatase mRNA expression.

Conclusions:

This study shows that melatonin inhibits aromatase activity and expression by regulating the gene expression of specific aromatase promoter regions. A possible mechanism for these effects would be the regulation by melatonin of intracellular cAMP levels, mediated by an inhibition of cyclooxygenase activity and expression.     

p53 Cooperates berberine-induced growth inhibition and apoptosis of non-small cell human lung cancer cells in vitro and tumor xenograft growth in vivo

Berberine has been shown to have anti-carcinogenic effects. Since p53 is the most commonly mutated tumor suppressor gene, and a lack of functional p53 is associated with an increased risk of cancer development, we examined the effects of berberine on p53-positive and p53-deficient non-small cell human lung cancer cells in vitro and in vivo. Treatment of A549, which express wild-type p53, and H1299, which are p53-deficient, human lung cancer cells with berberine resulted in inhibition of cell proliferation and an increase in apoptotic cell death; however, A549 cells were more sensitive to the berberine-induced cytotoxic effects than H1299 cells. Further, the treatment of A549 cells with pifithrin-alpha, a specific inhibitor of p53, or transfection of A549 cells with a p53 antisense oligodeoxynucleotide resulted in a reduction in the berberine-induced inhibition of cell proliferation and apoptosis. The berberine-induced apoptosis of both the A549 and H1299 human lung cancer cells was associated with the disruption of mitochondrial membrane potential, reduction in the levels of Bcl-2, Bcl-xl while increase in Bax, Bak, and activation of caspase-3. Treatment of the cells with pan-caspase inhibitor (z-VAD-fmk) or caspase-3 inhibitor (z-DEVD-fmk) inhibited berberine-induced apoptosis, thus suggesting the role of caspase-3. Further, the administration of berberine by oral gavage inhibited the growth of s.c. A549 and H1299 lung tumor xenografts in athymic nude mice, however, the growth of tumor xenograft of H1299 cells was faster than A549 cells in mice and the chemotherapeutic effect of berberine was more pronounced in the p53-positive-A549 tumor xenograft than p53-deficient-H1299 tumor xenograft.     

三羟异黄酮对MCF-7/HER-2乳腺癌细胞VEGF表达变化的影响

目的观察三羟异黄酮(genistein)对原癌基因HER-2/neu高表达乳腺癌细胞血管内皮生长因子(vascular endothelial growthfactor,VEGF)表达变化的影响,探讨genistein抗HER-2/neu高表达乳腺癌血管生成的分子机制.方法用基因转染技术建立HER-2/neu高表达的乳腺癌MCF-7细胞(命名为MCF-7/HER-2).5×10-5mol/L genistein处理MCF-7/HER-2细胞24、48、72 h后,应用免疫组织化学、Western blot及RT-PCR法检测genistein对MCF-7/HER-2乳腺癌细胞VEGF表达的变化.结果MCF-7/HER-2细胞与MCF-7细胞相比VEGF蛋白和mRNA表达增加,genistein处理MCF-7/HER-2细胞24、48、72 h后,VEGF的mRNA和蛋白表达量均下调,随着处理时间的延长,VEGF mRNA和蛋白表达量下降越明显.结论genistein能在转录和翻译水平下调HER-2/neu高表达乳腺癌细胞VEGF的表达,这可能是genistein抑制HER-2/neu高表达乳腺癌血管生成的机制之一.     

RNA干扰对乳腺癌MCF-7细胞株WT 1基因表达的抑制作用

目的：为探索治疗乳腺癌新途径，研究RNA干扰（RNA interferance，RNAi）对MCF-7细胞株WT 1基因表达的抑制作用。方法：设计制备多对针对WT 1基因的小干扰RNA（small interfering RNA，siRNA），转染MCF-7细胞，采用实时定量PCR（real—time quantitative polymerase chainreaction，RQ-PCR）法测定WT1 mRNA的表达，western blot测定WT1蛋白的表达，流式细胞仪检测加入长春新碱后的MCF-7细胞凋亡率。结果：siRNA能有效抑制WT1基因的表达，但不呈剂量关系，在较低浓度可维持RNAi至少4d时间，WT1基因表达下调的MCF-7细胞凋亡率增加。结论：RNAi能有效抑制MCF-7细胞中WT1基因的表达，同时转染siRNA后细胞对长春新碱敏感。     

不同化疗方案对MCF-7乳腺癌荷瘤裸鼠的抑瘤作用及对PCNA表达的影响

Objective: To investigate the antitumor activity of different combination regimens to human breast cancer xenograft (MCF-7) transplanted in nude mice and the effects on the expression of PCNA, and to evaluate the value of PCNA as predictive factor for the response of chemotherapy and individualized treatment. Methods: (1) 88 nude mice models of human breast cancer xenograft (MCF-7) were established, and then were randomly divided into control group and 10 chemotherapy groups (each group, n = 8). Among them, the mice of 5 chemotherapy groups were treated intraperitoneally/orally by 5 combination chemotherapy regimens (CMF, CAF, NP, TP, Xeloda) respectively at 1/3 LD10 dosage schedule (dose lethal to 10%of the mice), and that in another 5 chemotherapy groups were treated at 2/3 LD10 dosage schedule. Control animals were administered intraperitoneally with normal saline. (2) The body weight of nude mice and transplanted tumor growth were observed and recorded, then inhibition rate of tumor growth was calculated. (3) The pathological features of transplanted tumor were studied under microscope. The expression of proliferating cell nuclear antigen (PCNA) was comparatively studied in chemotherapy group and control group by SP immunohistochemical method and flow cytometry analysis. Results: (1) Body weight, tumor weight and inhibition rate of tumor growth of athymic mice bearing cancer: Body weights and tumor weights of nude mice in every 2/3 LD10 chemotherapy group were significantly lower than those of the control group (P ＜ 0.05), and the inhibition rates of tumor growth were 83.1%, 75.5%, 84.6%, 87.9% and 91.0%, respectively. Body weights of athymic mice in every 1/3 LD10 chemotherapy group were lower than that of the control (P ＜ 0.05). The results showed that the 2/3 LD10chemotherapy groups could reflect the effect of combination chemotherapy on the nude mice and the clinical dependability was better. So the data of 2/3 LD10 chemotherapy groups were appropriated for successive study. (2) Immunohistochemical studies: The expressions of PCNA in every chemotherapy group were significantly lower than that of the control (P ＜ 0.05).Moreover, the expression of PCNA in NP group was significantly lower than those of CMF, CAF, TP and Xeloda groups (P ＜0.05), while the expressions of TP and Xeloda groups were significantly lower than those of CMF and CAF groups (P ＜ 0.05).(3) FCM analysis: FI values of PCNA in every chemotherapy group were significantly lower than that of the control (P ＜ 0.05).FI values of PCNA in TP and Xeloda groups were significantly lower than those of CMF and CAF groups (P ＜ 0.05), while the value of NP group was significantly lower than that of CMF group (P ＜ 0.05). (4) Relationship between PCNA expression and pathologic response: The expression of PCNA was significantly correlated with pathological therapeutic response of transplanted breast carcinoma (P = 0.001). Conclusion: In vivo chemosensitivity testing with 2/3 LD10 dosage combinations in nude mice bearing cancer can reflect the effects of chemotherapeutics and affects of organism exactly. Various chemotherapy regimens all can decrease the expression of PCNA in breast cancer. The PCNA can be regarded as the factor to judge the response to chemotherapy, and it become possibly one of the prospective factors in the selection of chemotherapy regimen and play a rule in individualized therapy in the clinic.     

Ｓｕｒｖｉｖｉｎ、ＨＳＰ７０和Ｆａｓ在乳腺癌中的表达及其意义

目的　探讨人乳腺癌组织、癌旁正常乳腺组织中Ｓｕｒｖｉｖｉｎ、ＨＳＰ７０和Ｆａｓ的表达及其临床意义。方法　应用免疫组化法检测３６例患者的乳腺癌组织及癌旁正常乳腺组织标本中Ｓｕｒｖｉｖｉｎ、ＨＳＰ７０和Ｆａｓ蛋白的表达情况。结果　Ｓｕｒｖｉｖｉｎ、ＨＳＰ７０和Ｆａｓ在乳腺癌组织中的阳性表达率分别为８３.３％、８６.１％和５２.８％,在癌旁组织中表达率分别为４１.７％、６３.９％和９７.２％。Ｓｕｒｖｉｖｉｎ、ＨＳＰ７０在乳腺癌组织中的阳性表达率明显高于癌旁正常乳腺组织,而Ｆａｓ在乳腺癌组织中的阳性表达率明显低于癌旁正常乳腺组织。Ｓｕｒｖｉｖｉｎ、ＨＳＰ７０和Ｆａｓ的表达与年龄、病理类型、肿瘤直径、ＨＥＲ-２无显著性差异（Ｐ＞０.０５）;Ｓｕｒｖｉｖｉｎ和ＨＳＰ７０的表达率在有淋巴结转移组明显高于无淋巴结转移组（Ｐ＜０.０５）,而Ｆａｓ的表达率在有淋巴结转移组明显低于无淋巴结转移组（Ｐ＜０.０５）;且Ｓｕｒｖｉｖｉｎ在ＥＲ（－）／ＰＲ（－）组表达率高（Ｐ＜０.０５）。Ｓｕｒｖｉｖｉｎ与Ｆａｓ表达呈负相关（ｒ＝－０.４２３,Ｐ＜０.０５）;Ｓｕｒｖｉｖｉｎ与ＨＳＰ７０表达无明显相关性（ｒ＝０.２５１,Ｐ＞０.０５）。结论　Ｓｕｒｖｉｖｉｎ、ＨＳＰ７０上调及Ｆａｓ下调可能在乳腺癌发生发展中起着一定的作用。     

Relationship between the expressions of survivin and the prognostic related factors in breast cancer

Objective： To study the relationship between the Survivin expression and the histological grade, status of ER, expression of PS2 and the prognosis of patients with primary invasive breast cancer. Method： By using LSAB and SP immunohistochemical method, the expression of Survivin, PS2 and ER in 95 cases of invasive breast cancer were detected. Results： the positive rate of Survivin was 70.5% （67/95） and the expression of Survivin was positively related to the histological grade and status of PS2 and ER. The survival time after operation of patients without expression of Survivin was longer than those with positive Survivin. Conclusion： These data suggest that Survivin expression may be considered as a new unfavorable prognostic factor of breast cancer.     

Guggulsterone induces apoptosis in colon cancer cells and inhibits tumor growth in murine colorectal cancer xenografts

The plant sterol guggulsterone has recently been shown to have anti-tumorigenic potential. This study was designed to investigate the anti-tumor efficacy of guggulsterone and to elucidate its molecular mechanisms in colon cancer. Guggulsterone significantly increased apoptosis in HT-29 cells by activating caspases-3 and -8. Furthermore, guggulsterone decreased cIAP-1, cIAP-2, and Bcl-2 levels and increased the levels of truncated Bid, Fas, p-JNK, and p-c-Jun. The size of HT-29 xenograft tumors in guggulsterone-treated mice was significantly smaller than of the size of tumors in control mice. The present study suggests a potential therapeutic use for this compound in the treatment of colorectal cancer.