MicroRNA-181a suppresses norethisterone-promoted tumorigenesis of breast epithelial MCF10A cells through the PGRMC1/EGFR–PI3K/Akt/mTOR signaling pathway

BackgroundResearch suggests that hormone replacement therapy may increase the risk of breast cancer, and progestins such as norethisterone (NET) play a key role in this phenomenon. We have demonstrated that microRNA-181a (miR-181a) suppresses NET-promoted breast cancer cell survival. Nonetheless, the effects of NET and miR-181a on the tumorigenesis of human breast epithelial cells have not yet been elaborated.MethodsAssays of cell viability, proliferation, migration, apoptosis, and colony formation were performed to investigate the pro-tumorigenesis effect of NET and the effects of miR-181a on human breast epithelial MCF10A cells. The expressions of cell-proliferation-related genes and apoptotic factors were analyzed by quantitative RT-PCR and Western blot in MCF10A cells treated with NET and miR-181a.ResultsNET significantly increased MCF10A cell viability, proliferation, migration, and colony formation, but reduced cellular apoptosis. In addition, NET increased the expression of progesterone receptor membrane component 1 (PGRMC1), EGFR, B-cell lymphoma 2, cyclin D1, and proliferating cell nuclear antigen, but decreased the expression of pro-apoptosis factors, such as Bax, caspase-7, and caspase-9. Overexpression of miR-181a strongly inhibited the effects of NET on MCF10A cells and abrogated NET-stimulated PGRMC1, EGFR, and mTOR expression.ConclusionsActivation of the PGRMC1/EGFR–PI3K/Akt/mTOR signaling pathway is the primary mechanism underlying the pro-tumorigenesis effects of NET on human breast epithelial MCF10A cells. Additionally, miR-181a can suppress the effects of NET on these cells. These data suggest a therapeutic potential for miR-181a in reducing or preventing the risk of breast cancer in hormone replacement therapy using NET.     

miR-125b targets ARID3B in breast cancer cells

Mounting evidence suggests involvement of deregulated microRNA (miRNA) expression during the complex events of tumorigenesis. Among such deregulated miRNAs in cancer, miR-125b expression is reported to be consistently low in breast cancers. In this study, we screened a panel of breast cancer cell lines (BCCLs) for miR-125b expression and detected decreased expression in 14 of 19 BCCLs. Due to the heterogeneity of breast cancers, MCF7 cells were chosen as a model system for ERBB2 independent breast cancers to restore miR-125b expression (MCF7-125b) to investigate the phenotypical and related functional changes. Earlier, miR-125b was shown to regulate cell motility by targeting ERBB2 in ERBB2 overexpressing breast cancer cells. Here we showed decreased motility and migration in miR-125b expressing MCF7 cells, independent of ERBB2. MCF7-125b cells demonstrated profoundly decreased cytoplasmic protrusions detected by phalloidin staining of filamentous actin along with decreased motility and migration behaviors detected by in vitro wound closure and transwell migration assays compared to empty vector transfected cells (MCF7-EV). Among possible numerous targets of miR-125b, we showed ARID3B (AT-rich interactive domain 3B) to be a novel target with roles in cell motility in breast cancer cells. When ARID3B was transiently silenced, the decreased cell migration was also observed. In light of these findings, miR-125b continues to emerge as an interesting regulator of cancer related phenotypes.     

MiR-5047在乳腺癌细胞增殖迁移中的作用及表达调控*

探讨miR-5047在乳腺癌细胞中的表达及其在乳腺癌细胞增殖和迁移中的作用,并明确地西他滨在miR-5047表达调控中的作用。通过实时荧光定量PCR(qRT-PCR)检测人乳腺癌细胞系和正常乳腺上皮细胞MCF10A中miR-5047的表达水平;将miR-5047模拟物(mimic),阴性对照(NC)分别转染至MDA-MB-231和MCF7细胞,经平板克隆实验、MTT实验、划痕愈合实验检测乳腺癌细胞的增殖和迁移能力,通过qRT-PCR和Western blot检测相关基因表达及蛋白水平。使用浓度5 μmol/L和10 μmol/L的地西他滨分别处理MDA-MB-231和MCF-7细胞,经qRT-PCR检测不同浓度和处理时间条件下地西他滨对miR-5047表达的影响。同时,通过形态观察和Western blot检测地西他滨对乳腺癌细胞上皮间质转化的影响。与正常乳腺上皮细胞MCF-10A相比,miR-5047在乳腺癌细胞中表达均显著下调。miR-5047过表达可显著抑制乳腺癌细胞的增殖和迁移,促进上皮细胞标志物E-cadherin的表达,抑制间质细胞标志物Vimentin的表达。不同浓度地西他滨处理MDA-MB-231和MCF7细胞后,miR-5047表达均增强,且10 μmol/L作用48 h效果最显著。地西他滨可诱导MDA-MB-231细胞向上皮样转变。miR-5047在乳腺癌细胞系中表达显著下调,过表达miR-5047可抑制乳腺癌细胞的增殖和迁移,地西他滨可促进乳腺癌细胞中miR-5047的表达,并诱导细胞向上皮样转变。     

端粒酶RNA的反义cDNA对乳腺癌细胞凋亡的影响(英文)

 为了进一步探讨端粒酶RNA(hTR)的反义cDNA对乳腺癌MCF 7细胞凋亡可诱导性的影响 ,构建了能将外源基因整合至细胞基因组的整合型腺病毒载体vAd AAV ,并将hTR全长cDNA反向连接至此载体上 ,获得反义重组腺病毒vAdT AAV .vAd AAV和vAdT AAV分别感染MCF 7细胞后 ,获得两个细胞株MCF 7 vAd AAV和MCF 7 vAdT AAV ,其中MCF 7 vAdT AAV细胞基因组内整合有hTR反义cDNA并能稳定表达 .利用生存曲线、细胞形态学观察、DNA片段分析和流式细胞分析来测定NaBu和无血清DMEM诱导后细胞凋亡的反应性 .通过生存曲线 ,发现NaBu诱导的MCF 7 vAdT AAV细胞比对照组MCF 7和MCF 7 vAd AAV细胞更早出现凋亡 .电镜下 ,NaBu或去血清诱导的MCF 7 vAdT AAV细胞更早出现凋亡形态学指标 .流式细胞分析和DNA片段凝胶电泳实验均显示MCF 7 vAdT AAV细胞对凋亡的抵抗力下降 .研究结果表明 ,端粒酶RNA的反义cDNA使乳腺癌MCF 7细胞的凋亡可诱导性增强     

MiR-526b targets lncRNA SLC16A1-AS1 to suppress cell proliferation in triple-negative breast cancer

The present study investigated the potential interaction between miR-526b and lncRNA SLC16A1-AS1 in triple-negative breast cancer (TNBC). Expression of miR-526b and SLC16A1-AS1 in TNBC tumor tissues and paired nontumor tissues from 60 TNBC patients was detected by real-time polymerase chain reaction (RT-qPCR). The interaction between miR-526b and SLC16A1-AS1 was evaluated with overexpression experiments, followed by RT-qPCR. The proliferation and migration of cells were detected with cell counting kit-8 assay and Transwell assay, respectively. Apoptosis of cells was assessed by cell apoptosis assay. The expression of apoptosis-related proteins was quantified by Western blot analysis. MiR-526b was predicted to bind with SLC16A1-AS1. Overexpression of miR-526b in TNBC cells decreased the expression levels of SLC16A1-AS1, while overexpression of SLC16A1-AS1 did not affect the expression of miR-526b. In TNBC tissues, miR-526b was downregulated in TNBC tissues, while SLC16A1-AS1 was upregulated in TNBC tissues compared to that in nontumor tissues. The expression of SLC16A1-AS1 and miR-526b were inversely correlated. In vitro experiments showed that overexpression of SLC16A1-AS1 promoted cell proliferation and invasion but suppressed cell apoptosis. MiR-526b played an opposite role and suppressed the function of SLC16A1-AS1. MiR-526b is downregulated in TNBC and it targets SLC16A1-AS1 to regulate proliferation, apoptosis, and invasion of TNBC cells.     

Regulation of the P2X7R by microRNA-216b in human breast cancer

Breast cancer is the most common cancer in women around the world. However, the molecular mechanisms underlying breast cancer pathogenesis are only partially understood. Here, in this study, we found that P2X7R was up-regulated and miR-216b was down-regulated in breast cancer cell lines and tissues. Using bioinformatic analysis and 3′UTR luciferase reporter assay, we determined P2X7R can be directly targeted by miR-216b, which can down-regulate endogenous P2X7R mRNA and protein levels. Ectopic expression of miR-216b mimics leads to inhibited cell growth and apoptosis, while blocking expression of the miR-216b results in increased cell proliferation. Furthermore, our findings demonstrate that knockdown of P2X7R promotes apoptosis in breast cancer cells through down-regulating Bcl-2 and increasing the cleavage caspase-3 protein level. Finally, we confirmed that down-regulation of miR-216b in breast cancer is inversely associated with P2X7R expression level. Together, these findings establish miR-216b as a novel regulator of P2X7R and a potential therapeutic target for breast cancer.     

Clotrimazole preferentially inhibits human breast cancer cell proliferation, viability and glycolysis

Background

Clotrimazole is an azole derivative with promising anti-cancer effects. This drug interferes with the activity of glycolytic enzymes altering their cellular distribution and inhibiting their activities. The aim of the present study was to analyze the effects of clotrimazole on the growth pattern of breast cancer cells correlating with their metabolic profiles.

Methodology/Principal Findings

Three cell lines derived from human breast tissue (MCF10A, MCF-7 and MDA-MB-231) that present increasingly aggressive profiles were used. Clotrimazole induces a dose-dependent decrease in glucose uptake in all three cell lines, with K_i values of 114.3±11.7, 77.1±7.8 and 37.8±4.2 µM for MCF10A, MCF-7 and MDA-MB-231, respectively. Furthermore, the drug also decreases intracellular ATP content and inhibits the major glycolytic enzymes, hexokinase, phosphofructokinase-1 and pyruvate kinase, especially in the highly metastatic cell line, MDA-MB-231. In this last cell lineage, clotrimazole attenuates the robust migratory response, an effect that is progressively attenuated in MCF-7 and MCF10A, respectively. Moreover, clotrimazole reduces the viability of breast cancer cells, which is more pronounced on MDA-MB-231.

Conclusions/Significance

Clotrimazole presents deleterious effects on two human breast cancer cell lines metabolism, growth and migration, where the most aggressive cell line is more affected by the drug. Moreover, clotrimazole presents little or no effect on a non-tumor human breast cell line. These results suggest, at least for these three cell lines studied, that the more aggressive the cell is the more effective clotrimazole is.     

Elucidating progesterone effects in breast cancer: cross talk with PDGF signaling pathway in smooth muscle cell

Several studies indicate that progesterone exerts relevant effects in breast tissue. However, the exact role of this steroid in breast cancer development and progression has not been elucidated. Here, we show that platelet-derived growth factor (PDGF)-A is one of the progesterone target genes on breast cancer MCF7 and T47D cells. A paracrine role for PDGF-A was investigated, since its receptor expression was down-regulated from breast cancer cells. Progesterone increased PDGF-A protein release as evaluated by Western blotting and ELISA. Medium from Progesterone-treated MCF7 cells resulted in phosphorylation of smooth muscle cells PDGF receptor alpha. This effect was not observed after treatment with PDGF inhibitor. MCF7 cells-secreted PDGF-A was able to increase smooth muscle cell viability and proliferation and decrease apoptosis, effects that were prevented by the use of a PDGF-A neutralizing antibody. Notably, cell invasion was not influenced by PDGF-A secreted by MCF7 cells. Our results elucidated for the first time the cross talk between progesterone and PDGF signaling pathway. The fact that MCF7-secreted PDGF elicited crucial roles in vascular wall smooth muscle cells, suggested a paracrine pathway for progesterone. Targeting these progesterone-induced processes may provide novel therapeutic strategies for hormone-dependent human breast cancer.     

Retracted: Downregulation of microRNA-1469 promotes the development of breast cancer via targeting HOXA1 and activating PTEN/PI3K/AKT and Wnt/β-catenin pathways

Breast cancer (BC) is a common malignancy which is the most frequently diagnosed cancer in women all over the worldwide. This study aimed to investigate the roles of miR-1469 in the development of BC, as well as its regulatory mechanism. The expression levels of miR-1469 in BC tissues, serum, and cell lines were determined. Effects of overexpression of miR-1469 on MCF7 cell viability, colony-forming ability, apoptosis, migration, and invasion were then investigated. Furthermore, the potential target of miR-1469 in MCF7 cells was explored. Besides, the association between miR-1469, PTEN/PI3K/AKT, and Wnt/β-catenin pathways was elucidated. Notably, confirmatory experiments by downregulation of miR-1469 in SK-BR-3 cells were further performed. The miR-1469 expression was significantly downregulated in BC tissues, serum, and cell lines. The overexpression of miR-1469 significantly inhibited the proliferation, arrested cell-cycle at G2/M phase, increased apoptosis, suppressed migration, and invasion of MCF-7 cells. In addition, HOXA1 was verified as a direct target of miR-1469, and the effects of overexpression of miR-1469 on the malignant behaviors of MCF7 cells were significantly counteracted by overexpression of HOXA1 concurrently. Furthermore, the overexpression of miR-1469 suppressed the activation of PTEN/PI3K/AKT and Wnt/β-catenin pathways, which was reversed overexpression of HOXA1 concurrently. Besides, confirmatory experiments showed that the inhibition of miR-1469 promoted the malignant behaviors of SK-BR-3 cells, which was inversed after miR-1469 inhibition and HOXA1 knockdown at the same time. Our findings reveal that downregulation of miR-1469 may promote the development of BC by targeting HOXA1 and activating PTEN/PI3K/AKT and Wnt/β-catenin pathways. MiR-1469 may serve as a promising target for BC therapy.     

Effects of miR-21 downregulation and silibinin treatment in breast cancer cell lines

Silibinin is a natural polyphenol with high antioxidant and anticancer properties, which causes cell cycle arrest and apoptosis in most cancer cell types including breast cancer, but the in-line mechanisms, are still unknown. Silibinin significantly downregulated oncomiR miR-21 expression in breast cancer cells. Here the effect of anti-miR-21 on cell viability, apoptotic induction, cell cycle distribution, and the expression levels of downstream targets of miR-21 were investigated in MCF-7 and T47D cells. MiR-21 mimic transfection was also applied in silibinin treated samples to evaluate functional role of miR-21downregulation on silibinin effects. It was found that after anti-miR-21 transfection, no significant changes were detected in cell viability, apoptosis (except early apoptosis), and cell cycle in MCF-7 and T47D cells. Compared to silibinin, miR-21 mimic transfection in combination with silibinin caused a slight modulation in some of the examined silibinin effects including apoptosis, Bcl2 mRNA and PTEN mRNA and protein levels. Silibinin slightly changed luciferase activity from reporters containing the miR-21 recognition elements from PTEN-3′UTR and Bcl2-3′UTR in both cell lines. Together these data demonstrated negligible cancer-progression impact of miR-21 and limited roles of miR-21 downregulation in examined silibinin effects, and strengthened the anti-cancer pathways of silibinin other than miR-21downregulation in MCF-7 and T47D cells.     

SLC6A14 (ATB0,+) protein, a highly concentrative and broad specific amino acid transporter, is a novel and effective drug target for treatment of estrogen receptor-positive breast cancer

SLC6A14, also known as ATB(0,+), is an amino acid transporter with unique characteristics. It transports 18 of the 20 proteinogenic amino acids. However, this transporter is expressed only at low levels in normal tissues. Here, we show that the transporter is up-regulated specifically in estrogen receptor (ER)-positive breast cancer, demonstrable with primary human breast cancer tissues and human breast cancer cell lines. SLC6A14 is an estrogen/ER target. The transport features of SLC6A14 include concentrative transport of leucine (an activator of mTOR), glutamine (an essential amino acid for nucleotide biosynthesis and substrate for glutaminolysis), and arginine (an essential amino acid for tumor cells), suggesting that ER-positive breast cancer cells up-regulate SLC6A14 to meet their increased demand for these amino acids. Consequently, treatment of ER-positive breast cancer cells in vitro with α-methyl-DL-tryptophan (α-MT), a selective blocker of SLC6A14, induces amino acid deprivation, inhibits mTOR, and activates autophagy. Prolongation of the treatment with α-MT causes apoptosis. Addition of an autophagy inhibitor (3-methyladenine) during α-MT treatment also induces apoptosis. These effects of α-MT are specific to ER-positive breast cancer cells, which express the transporter. The ability of α-MT to cause amino acid deprivation is significantly attenuated in MCF-7 cells, an ER-positive breast cancer cell line, when SLC6A14 is silenced with shRNA. In mouse xenograft studies, α-MT by itself is able to reduce the growth of the ER-positive ZR-75-1 breast cancer cells. These studies identify SLC6A14 as a novel and effective drug target for the treatment of ER-positive breast cancer.     

Acetonic extract of Buxus sempervirens induces cell cycle arrest, apoptosis and autophagy in breast cancer cells

Plants are an invaluable source of potential new anti-cancer drugs. Here, we investigated the cytotoxic activity of the acetonic extract of Buxus sempervirens on five breast cancer cell lines, MCF7, MCF10CA1a and T47D, three aggressive triple positive breast cancer cell lines, and BT-20 and MDA-MB-435, which are triple negative breast cancer cell lines. As a control, MCF10A, a spontaneously immortalized but non-tumoral cell line has been used. The acetonic extract of Buxus sempervirens showed cytotoxic activity towards all the five studied breast cancer cell lines with an IC(50) ranging from 7.74 μg/ml to 12.5 μg/ml. Most importantly, the plant extract was less toxic towards MCF10A with an IC(50) of 19.24 μg/ml. Fluorescence-activated cell sorting (FACS) analysis showed that the plant extract induced cell death and cell cycle arrest in G0/G1 phase in MCF7, T47D, MCF10CA1a and BT-20 cell lines, concomitant to cyclin D1 downregulation. Application of MCF7 and MCF10CA1a respective IC(50) did not show such effects on the control cell line MCF10A. Propidium iodide/Annexin V double staining revealed a pre-apoptotic cell population with extract-treated MCF10CA1a, T47D and BT-20 cells. Transmission electron microscopy analyses indicated the occurrence of autophagy in MCF7 and MCF10CA1a cell lines. Immunofluorescence and Western blot assays confirmed the processing of microtubule-associated protein LC3 in the treated cancer cells. Moreover, we have demonstrated the upregulation of Beclin-1 in these cell lines and downregulation of Survivin and p21. Also, Caspase-3 detection in treated BT-20 and T47D confirmed the occurrence of apoptosis in these cells. Our findings indicate that Buxus sempervirens extract exhibit promising anti-cancer activity by triggering both autophagic cell death and apoptosis, suggesting that this plant may contain potential anti-cancer agents for single or combinatory cancer therapy against breast cancer.     

Abnormal levels and minimal activity of the dsRNA-activated protein kinase, PKR, in breast carcinoma cells

The interferon induced, dsRNA-activated, protein kinase, PKR, is a key regulator of translational initiation, playing an important role in the regulation of cell proliferation, apoptosis and transformation. PKR levels correlate inversely with proliferative activity in several human tumor systems. This inverse relationship breaks down in human invasive ductal breast carcinomas which exhibit high levels of PKR (Haines et al., Tumor Biol. 17 (1996) 5-12). Consistent with the data from human tumors, the levels of PKR in several breast carcinoma cell lines, MCF7, T47D, BT20, MDAMB231 and MDAMB468, are paradoxically high compared to those found in the normal breast cell lines MCF10A and Hs578Bst. The activity of affinity- or immuno-purified PKR from MCF7, T47D, and BT20 cells appears to be severely attenuated, as judged by its ability to autophosphorylate, or phosphorylate eIF2 alpha. Furthermore, the activity of the kinase from breast carcinoma cells is refractory to stimulation by dsRNA or heparin. However, PKR from breast carcinoma cells remains functional with respect to its ability to bind dsRNA. The activity of PKR from MCF10A cells is reduced by prior incubation with extracts from MCF7 cells, suggesting that MCF7 extracts contain a transdominant inhibitor of PKR. Deregulation of PKR may therefore provide a mechanism for the development or maintenance of a transformed phenotype of human breast carcinomas, mimicking the effects of manipulation of PKR or eIF2 activity observed in experimental systems. Thus, breast carcinomas may provide the first indication of a role for PKR in the pathogenesis of a naturally occurring human cancer.     

Assessment of Interactions between Cisplatin and Two Histone Deacetylase Inhibitors in MCF7, T47D and MDA-MB-231 Human Breast Cancer Cell Lines – An Isobolographic Analysis

Histone deacetylase inhibitors (HDIs) are promising anticancer drugs, which inhibit proliferation of a wide variety of cancer cells including breast carcinoma cells. In the present study, we investigated the influence of valproic acid (VPA) and suberoylanilide hydroxamic acid (SAHA, vorinostat), alone or in combination with cisplatin (CDDP) on proliferation, induction of apoptosis and cell cycle progression in MCF7, T47D and MDA-MB-231 human breast carcinoma cell lines. The type of interaction between HDIs and CDDP was determined by an isobolographic analysis. The isobolographic analysis is a very precise and rigorous pharmacodynamic method, to determine the presence of synergism, addition or antagonism between different drugs with using variety of fixed dose ratios. Our experiments show that the combinations of CDDP with SAHA or VPA at a fixed-ratio of 1:1 exerted additive interaction in the viability of MCF7 cells, while in T47D cells there was a tendency to synergy. In contrast, sub-additive (antagonistic) interaction was observed for the combination of CDDP with VPA in MDA-MB-231 “triple-negative” (i.e. estrogen receptor negative, progesterone receptor negative, and HER-2 negative) human breast cancer cells, whereas combination of CDDP with SAHA in the same MDA-MB-231 cell line yielded additive interaction. Additionally, combined HDIs/CDDP treatment resulted in increase in apoptosis and cell cycle arrest in all tested breast cancer cell lines in comparison with a single therapy. In conclusion, the additive interaction of CDDP with SAHA or VPA suggests that HDIs could be combined with CDDP in order to optimize treatment regimen in some human breast cancers.     

Annexin-A1 Regulates MicroRNA-26b* and MicroRNA-562 to Directly Target NF-κB and Angiogenesis in Breast Cancer Cells

Annexin 1 (ANXA1) is an endogenous anti-inflammatory protein implicated in cancer. ANXA1 was previously shown to be regulated by hsa-miR-196a. However, whether ANXA1 itself regulates microRNA (miR) expression is unknown. Therefore, we investigated the regulation of miR by ANXA1 in MCF7 breast cancer cells. MCF7-EV (Empty vector) and MCF7-V5 (ANXA1-V5 expressing cells) were subjected to a miR microarray. Microarray analysis revealed a number of miRNAs which were dysregulated in MCF7-V5 cells. 2 novel miRNAs (miR562 and miR26b*) were validated, cloned and functionally characterized. As ANXA1 constitutively activates NF-κB activity to modulate breast cancer metastasis, we found that miR26b* and miR562 directly targeted the canonical NF-κB pathway by targeting the 3′ UTR and inhibiting expression of Rel A (p65) and NF-κB1 (p105) respectively. MiR562 inhibited wound healing, which was reversed when ANXA1 was overexpressed. Overexpression of either miR562 or miR26b* in MCF-7 cells enhanced endothelial tube formation when cocultured with human umbilical cord endothelial cells while conversely, treatment of MCF7 cells with either anti-miR562 or anti-miR26b* inhibited endothelial tube formation after co-culture. Further analysis of miR562 revealed that miR562-transfected cell conditioned media enhances endothelial cell tube formation, indicating that miR562 increased angiogenic secreted factors from MCF-7 breast tumor cells. TNFα was increased upon overexpression of miR562, which was reversed when ANXA1 was co-transfected In conclusion, this data suggests that ANXA1-regulated miR26b* and miR562 may play a role in wound healing and tumor-induced endothelial cell tube formation by targeting NF-κB expression and point towards a potential therapeutic target for breast cancer.     

Apoptosis‐inducing effect of garcinol is mediated by NF‐κB signaling in breast cancer cells

Garcinol, obtained from Garcinia indica in tropical regions, is used for its numerous biological effects. Its anti‐cancer activity has been suggested but the mechanism of action has not been studied in‐detail, especially there is no report on its action against breast cancer cells. Here we tested our hypothesis that garcinol may act as an anti‐proliferative and apoptosis‐inducing agent against breast cancer cell lines. Using multiple techniques such as MTT, Histone‐DNA ELISA, Annexin V‐PI staining, Western blot for activated caspases and cleaved PARP, homogenous caspase‐3/7 fluorometric assay and EMSA, we investigated the mechanism of apoptosis‐inducing effect of garcinol in ER‐positive MCF‐7 and ER‐negative MDA‐MB‐231 cells. We found that garcinol exhibits dose‐dependent cancer cell‐specific growth inhibition in both the cell lines with a concomitant induction of apoptosis, and has no effect on non‐tumorigenic MCF‐10A cells. Our results suggested induction of caspase‐mediated apoptosis in highly metastatic MDA‐MB‐231 cells by garcinol. Down‐regulation of NF‐κB signaling pathway was observed to be the mechanism of apoptosis‐induction. Garcinol inhibited constitutive NF‐κB activity, which was consistent with down‐regulation of NF‐κB‐regulated genes. This is the first report on anti‐proliferative and apoptosis‐inducing action of garcinol against human breast cancer cells and the results suggest that this natural compound merits investigation as a potential chemo‐preventive/‐therapeutic agent, especially against breast cancer. J. Cell. Biochem. 109: 1134–1141, 2010. © 2010 Wiley‐Liss, Inc.