Green tea polyphenol epigallocatechin-3 gallate (EGCG) affects gene expression of breast cancer cells transformed by the carcinogen 7,12-dimethylbenz[a]anthracene

Extracellular vesicle isolation, purification and evaluation in cancer diagnosis

Strategies for non-invasive biomarker discovery in early detection of cancer are an urgent need. Extracellular vesicles (EVs) have generated increasing attention from the scientific community and are under intensive investigations due to their unique biological profiles and their non-invasive nature. EVs are membrane-enclosed vesicles with variable sizes and function. Such vesicles are actively secreted from multiple cell types and are considered as key vehicles for inter-cellular communications and signalling. The stability and potential to easily cross biological barriers enable EVs for exerting durable effects on target cells. These along with easy access to such vesicles, the consistent secretion from tumour during all stages of tumorigenesis and their content providing a reservoir of molecules as well as mirroring the identity of the cell of origin are virtues that have made EVs appealing to be assessed in liquid biopsy approaches and for using as a promising resource of biomarkers in cancer diagnosis and therapy and monitoring targeted cancer therapy. Early detection of EVs will guide time-scheduled personalised therapy. Surveying reliable and sensitive methods for rapid isolation of EVs from biofluids, the purity of isolated vesicles and their molecular profiling and marker specification for clinical translation in patients with cancer are issues in the area and the hot topics of many recent studies. Here, the focus is over methods for EV isolation and stratification for digging more information about liquid biopsy-based diagnosis. Extending knowledge regarding EV-based strategies is a key to validate independent patient follow-up for cancer diagnosis at early stages and inspecting the efficacy of therapeutics.

The Role of EGCG in Breast Cancer Prevention and Therapy

BACKGROUND

Breast cancer is the most frequent cancer in women. Green tea has been studied for breast cancer chemopreventive and possibly chemotherapeutic effects due to its high content in polyphenolic compounds, including epigallocatechin-3-gallate (EGCG).

METHOD

This review is based on literature research that included papers registered on the Medline® database. The research was conducted through PubMed, applying the following query: "EGCG"AND "breast cancer". The result was a total of 88 articles in which this review stands on.

RESULTS

In vitro, EGCG shows antioxidant or pro-oxidant properties, depending on the concentration and exposure time. EGCG blocks cell cycle progression and modulates signaling pathways that affect cell proliferation and differentiation. EGCG also induces apoptosis, negatively modulates different steps involved in metastasis, and targets angiogenesis by inhibiting VEGF transcription. In vivo investigations have shown that oral administration of EGCG results in the reduction of tumor growth and in antimetastatic and antiangiogenic effects in animal xenograft and allograft models.

DISCUSSION

Much remains unknown about the molecular mechanisms involved in the protective effects of EGCG on mammary carcinogenesis. In addition, more studies in vivo are necessary to determine the potential toxicity of EGCG at higher doses and to elucidate its interactions with other drugs.

CONCLUSION

A protective effect of EGCG has been shown in different experimental models and under different experimental conditions, suggesting clinical implications of EGCG for breast cancer prevention and therapy. The data presented in this review support the importance of further investigations.

S-adenosyl-L-homocysteine Hydrolase: Its Inhibitory Activity Against Plasmodium falciparum and Development of Malaria Drugs

Parasite Plasmodium falciparum is continuously giving a challenge to human beings by changing itself against most of the antimalarial drugs and its consequences can be seen in the form of a huge number of deaths each year especially in the poor and developing country. Due to its drug resistance ability, new drugs are regularly needed to kill the organism. Many new drugs have been developed based on different mechanisms. One of the potential mechanisms is to hamper protein synthesis by blocking the gene expression. S-Adenosyl-L-homocysteine (SAH) hydrolase is a NAD+ dependent tetrameric enzyme, which is responsible for the reversible hydrolysis of AdoHcy to adenosine and L-homocysteine, has been recognized as a new target for antimalarial agents since the parasite has a specific SAH hydrolase. The inhibition of SAH hydrolase causes the intracellular accumulation of S-Adenosyl-L-homocysteine, elevating the ratio of SAH to S-adenosylmethionine (SAM) and inhibiting SAM-dependent methyltransferase that catalyzes methylation of the capped structure at the 5'-terminus of mRNA, and other methylation reaction which is essential for parasite proliferation. In other words, S-Adenosyl-Lhomocysteine hydrolase regulates methyltransferase reactions. In this way, SAH hydrolase inhibitors can be used for the treatment of different diseases like malaria, cancer, viral infection, etc. by ultimately stopping the synthesis of protein. Many antiviral drugs have been synthesized and marketed which are based on the inhibition of SAH hydrolase. This review summarises the development of SAH inhibitors developed over the last 20 years and their potentiality for the treatment of malaria.

Protective Effects of Epigallocatechin Gallate (EGCG) on Endometrial, Breast, and Ovarian Cancers

Green tea and its major bioactive component, (-)-epigallocatechin gallate (EGCG), possess diverse biological properties, particularly antiproliferation, antimetastasis, and apoptosis induction. Many studies have widely investigated the anticancer and synergistic effects of EGCG due to the side effects of conventional cytotoxic agents. This review summarizes recent knowledge of underlying mechanisms of EGCG on protective roles for endometrial, breast, and ovarian cancers based on both in vitro and in vivo animal studies. EGCG has the ability to regulate many pathways, including the activation of nuclear factor erythroid 2-related factor 2 (Nrf2), inhibition of nuclear factor-κB (NF-κB), and protection against epithelial-mesenchymal transition (EMT). EGCG has also been found to interact with DNA methyltransferases (DNMTs) and histone deacetylases (HDACs), which affect epigenetic modifications. Finally, the action of EGCG may exert a suppressive effect on gynecological cancers and have beneficial effects on auxiliary therapies for known drugs. Thus, future clinical intervention studies with EGCG will be necessary to more and clear evidence for the benefit to these cancers.

Combinatorial Epigenetics Impact of Polyphenols and Phytochemicals in Cancer Prevention and Therapy

Polyphenols are potent micronutrients that can be found in large quantities in various food sources and spices. These compounds, also known as phenolics due to their phenolic structure, play a vital nutrient-based role in the prevention of various diseases such as diabetes, cardiovascular diseases, neurodegenerative diseases, liver disease, and cancers. However, the function of polyphenols in disease prevention and therapy depends on their dietary consumption and biological properties. According to American Cancer Society statistics, there will be an expected rise of 23.6 million new cancer cases by 2030. Due to the severity of the increased risk, it is important to evaluate various preventive measures associated with cancer. Relatively recently, numerous studies have indicated that various dietary polyphenols and phytochemicals possess properties of modifying epigenetic mechanisms that modulate gene expression resulting in regulation of cancer. These polyphenols and phytochemicals, when administrated in a dose-dependent and combinatorial-based manner, can have an enhanced effect on epigenetic changes, which play a crucial role in cancer prevention and therapy. Hence, this review will focus on the mechanisms of combined polyphenols and phytochemicals that can impact various epigenetic modifications such as DNA methylation and histone modifications as well as regulation of non-coding miRNAs expression for treatment and prevention of various types of cancer.

Phytochemicals as Modulators of Long Non-Coding RNAs and Inhibitors of Cancer-Related Carbonic Anhydrases

Long non-coding RNAs (lncRNAs) are classified as a group of transcripts which regulate various biological processes, such as RNA processing, epigenetic control, and signaling pathways. According to recent studies, lncRNAs are dysregulated in cancer and play an important role in cancer incidence and spreading. There is also an association between lncRNAs and the overexpression of some tumor-associated proteins, including carbonic anhydrases II, IX, and XII (CA II, CA IX, and CA XII). Therefore, not only CA inhibition, but also lncRNA modulation, could represent an attractive strategy for cancer prevention and therapy. Experimental studies have suggested that herbal compounds regulate the expression of many lncRNAs involved in cancer, such as HOTAIR (HOX transcript antisense RNA), H19, MALAT1 (metastasis-associated lung adenocarcinoma transcript 1), PCGEM1 (Prostate cancer gene expression marker 1), PVT1, etc. These plant-derived drugs or phytochemicals include resveratrol, curcumin, genistein, quercetin, epigallocatechin-3-galate, camptothcin, and 3,3'-diindolylmethane. More comprehensive information about lncRNA modulation via phytochemicals would be helpful for the administration of new herbal derivatives in cancer therapy. In this review, we describe the state-of-the-art and potential of phytochemicals as modulators of lncRNAs in different types of cancers.

Bioinformatics analysis of microarray profiling identifies the mechanism of focal adhesion kinase signalling pathway in proliferation and apoptosis of breast cancer cells modulated by green tea polyphenol epigallocatechin 3-gallate

OBJECTIVES

This study aimed to investigate potential gene and signal pathway associated with tumour progression.

METHODS

Related microarray data set of breast cancer was obtained from Gene Expression Omnibus database, and differential-expressed genes (DEGs) between two control samples and two treated samples were analysed using statistical software R. We collected 50 epigallocatechin-3-gallate(EGCG)-related genes and 119 breast cancer-related genes to create a knowledge base for following pathway analysis.

KEY FINDINGS

A total of 502 mRNAs were identified as DEGs based on microarray analysis. Upregulated DEGs mainly enriched in nuclear nucleosome, cell adhesion, DNA packaging complex, Wnt-activated receptor activity, etc., while the downregulated DEGs significantly enriched in ncRNA processing, mitotic nuclear division, DNA helicase activity, etc. DEGs mostly enriched in gap junction, cell cycle, oxidative phosphorylation, focal adhesion, etc. EGCG suppressed FAK signalling pathway. Furthermore, EGCG could inhibit breast cancer cell proliferation and promote apoptosis by modulating CCND1.

CONCLUSIONS

Epigallocatechin 3-gallate might exert influence on breast cancer progression through inhibiting focal adhesion kinase (FAK) signalling pathway.

Combinatorial epigenetic mechanisms and efficacy of early breast cancer inhibition by nutritive botanicals

Aim:

Aberrant epigenetic events are important contributors to the pathogenesis of different types of cancers and dietary botanicals with epigenetic properties can influence early cancer development leading to cancer prevention effects. We sought to investigate potential combinatorial effects of bioactive dietary components including green tea polyphenols (GTPs) and broccoli sprouts (BSp) on neutralizing epigenetic aberrations during breast tumorigenesis.

Materials & methods:

The combinatorial effects were evaluated in a breast cancer transformation cellular system and breast cancer mouse xenografts.

Results & conclusion:

Combined treatment with epigallocatechin-3-gallate in GTPs and sulforaphane in BSp resulted in a synergistic inhibition of breast cancer cellular growth. Further studies revealed this combination led to genome-wide epigenetic alterations. Combinatorial diets significantly inhibited tumor growth in breast cancer mouse xenografts. Collectively, these studies indicate that combined GTPs and BSp are highly effective in inhibiting early breast cancer development by, at least in part, regulating epigenetic mechanisms.

Identification of a novel Calotropis procera protein that can suppress tumor growth in breast cancer through the suppression of NF-κB pathway

Breast cancer is the most common cancer among women. To date, improvements in hormonal and cytotoxic therapies have not yet led to a sustained remission or cure. In the present study, we investigated the in vitro and in vivo antitumor activities of a novel Calotropis procera protein (CP-P) isolated from root bark. CP-P protein inhibited the proliferation and induced apoptosis of breast cancer cells through the suppression of nuclear factor kappaB (NF-kB) activation. CP-P, when administered individually or in combination with cyclophosphamide (CYC, 0.2 mg/kg) to rats with 7, 12-dimethyl benz(a)anthracene (DMBA)-induced breast cancer decreased tumor volume significantly without affecting the body weight. To elucidate the anticancer mechanism of CP-P, antioxidant activities such as superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST) and non-enzymatic antioxidant - reduced glutathione (GSH), vitamin E and C generation in the breast were analyzed by various assays. SOD, CAT, GST, GSH, vitamin E and C levels were high in combination-treated groups (CP-P+CYC) versus the CYC alone-treated groups. Also, the combination was more effective in down-regulating the expression of NF-kB-regulated gene products (cyclin D1 and Bcl-2) in breast tumor tissues. Our findings indicate that CP-P possesses significant antitumor activity comparable to a commonly used anticancer drug, cyclophosphamide, and may form the basis of a novel therapy for breast cancer.

Epigallocatechin gallate sensitizes CAL-27 human oral squamous cell carcinoma cells to the anti-metastatic effects of gefitinib (Iressa) via synergistic suppression of epidermal growth factor receptor and matrix metalloproteinase-2

Human head and neck squamous cell carcinoma (HNSCC) is a major cause of cancer-related death during the last decade due to its related metastasis and poor treatment outcomes. Gefitinib (Iressa), a tyrosine kinase inhibitor has been reported to reduce the metastatic abilities of oral cancer. Previous studies have shown that epigallocatechin gallate (EGCG), a green tea polyphenol, possesses cancer chemopreventive and anticancer activity. However, the mechanisms involved in the suppression of invasion and metastasis of human oral cancer cells following co-incubation with gefitinib and EGCG remain poorly understood. In the present study, we attempted to investigate the synergistic effects of a combined treatment of gefitinib and EGCG in CAL-27 cells in vitro and to elucidate the underlying molecular mechanisms associated with the supression of cell migration and invasion. In the present study, we found that the individual treatments or the combined treatment of gefitinib and EGCG synergistically inhibited the invasion and migration of CAL-27 cells using Transwell invasion and wound-healing scratch assays, respectively. Similarly, gefitinib in combination with EGCG synergistically attenuated enzymatic activity and the protein expression of MMP-2 in CAL-27 cells. Furthermore, individual or combined treatment with EGCG and gefitinib suppressed the protein expression of p-EGFR and the phosphorylated protein levels of ERK, JNK, p38 and AKT and displayed inhibitory effects on metastatic ability of CAL-27 cells. Combined effects of EGCG and gefitinib-altered anti-metastatic actions for related gene expression were observed using DNA microarray analysis. Importantly, EGCG sensitizes CAL-27 cells to gefitinib-suppressed phosphorylation of epidermal growth factor receptor (EGFR in vitro. Taken together, our results suggest that the synergistic suppression of the metastatic ability of CAL-27 cells after EGCG and gefitinib individual or combined treatment are mediated through mitogen-activated protein kinase (MAPK) signaling. Our novel findings provide potential insights into the mechanism involved with synergistic responses of gefitinib and EGCG against the progression of oral cancer.

Biochemical basis for functional ingredient design from fruits

Functional food ingredients (nutraceuticals) in fruits range from small molecular components, such as the secondary plant products, to macromolecular entities, e.g., pectin and cellulose, that provide several health benefits. In fruits, the most visible functional ingredients are the color components anthocyanins and carotenoids. In addition, several other secondary plant products, including terpenes, show health beneficial activities. A common feature of several functional ingredients is their antioxidant function. For example, reactive oxygen species (ROS) can be oxidized and stabilized by flavonoid components, and the flavonoid radical can undergo electron rearrangement stabilizing the flavonoid radical. Compounds that possess an orthodihydroxy or quinone structure can interact with cellular proteins in the Keap1/Nrf2/ARE pathway to activate the gene transcription of antioxidant enzymes. Carotenoids and flavonoids can also exert their action by modulating the signal transduction and gene expression within the cell. Recent results suggest that these activities are primarily responsible for the health benefits associated with the consumption of fruits and vegetables.

Lunasin-aspirin combination against NIH/3T3 cells transformation induced by chemical carcinogens

Carcinogenesis is a multistage process involving a number of molecular pathways sensitive to intervention. Chemoprevention is defined as the use of natural and/or synthetic substances to block, reverse, or retard the process of carcinogenesis. To achieve greater inhibitory effects on cancer cells, combination of two or more chemopreventive agents is commonly considered as a better preventive and/or therapeutic strategy. Lunasin is a promising cancer preventive peptide identified in soybean and other seeds. Its efficacy has been demonstrated by both in vitro and in vivo models. This peptide has been found to inhibit human breast cancer MDA-MB-231 cells proliferation, suppressing cell cycle progress and inducing cell apoptosis. Moreover, lunasin potentiates the effects on these cells of different synthetic and natural compounds, such as aspirin and anacardic acid. This study explored the role of lunasin, alone and in combination with aspirin and anacardic acid on cell proliferation and foci formation of transformed NIH/3T3 cells induced by chemical carcinogens 7,12-dimethylbenz[a]anthracene or 3-methylcholanthrene. The results revealed that lunasin, acting as a single agent, inhibits cell proliferation and foci formation. When combined with aspirin, these effects were significantly increased, indicating that this combination might be a promising strategy to prevent/treat cancer induced by chemical carcinogens.

Functional genomics of endothelial cells treated with anti-angiogenic or angiopreventive drugs

Angiogenesis is a highly regulated physiological process that has been studied in considerable detail given its importance in several chronic pathologies. Many endogenous factors and hormones intervene in the regulation of angiogensis and classical as well as targeted drugs have been developed for its control. Angiogenesis inhibition has come off the bench and entered into clinical application for cancer therapy, particularly for metastatic disease. While the clinical benefit is currently in terms of months, preclinical data suggest that novel drugs and drug combinations could lead to substantial improvement. The many targets of endogenous angiogenesis inhibitors reflect the complexity of the process; in contrast, current clinical therapies mainly target the vascular endothelial growth factor system. Cancer chemopreventive compounds can retard tumor insurgence and delay or prevent metastasis and many of these molecules hinder angiogenesis, a mechanism that we termed angioprevention. Angiopreventive drugs appear to prevalently act through the inhibition of the pro-inflammatory and anti-apoptotic player NFkappaB, thus contrasting inflammation dependent angiogenesis. Relatively little is known concerning the effects of these angiogenesis inhibitors on gene expression of endothelial cells, the main target of many of these molecules. Here we provide an exhaustive list of anti-angiogenic molecules, and summarize their effects, where known, on the transcriptome and functional genomics of endothelial cells. The regulation of specific genes can be crucial to preventive or therapeutic intervention. Further, novel targets might help to circumvent resistance to anti-angiogenic therapy. The studies we review are relevant not only to cancer but also to other chronic degenerative diseases involving endothelial cells, such as cardiovascular disorders, diabetes, rheumatoid arthritis and retinopaties, as well as vessel aging.

Grape and wine polyphenols down-regulate the expression of signal transduction genes and inhibit the growth of estrogen receptor-negative MDA-MB231 tumors in nu/nu mouse xenografts

The antitumor properties of the Merlot grape (and Merlot wine) polyphenols were evaluated in relation to their ability to modulate gene expression in developing tumors using an athymic nude mouse model transplanted with the estrogen receptor-negative MDA-MB231 cells. Groups of mice were fed a modified AIN 93G diet (Research Diets Inc, New Brunswick, NJ) with the experimental groups receiving 100 mg/kg body weight equivalent of polyphenols by gavage 3 times per week. After 1 week of acclimation and another week of polyphenol supplementation, MDA-MB231 cells were transplanted and the growth patterns of the tumors monitored. After 33 days of tumor growth, the animals were euthanized, the tumors isolated, and gene expression profiles analyzed using signal transduction and cell cycle arrays. The development of tumors was almost totally arrested in grape polyphenol-treated mice. Total polyphenols isolated from the wine were more effective in reducing tumor growth as compared with a hydrophobic polyphenol fraction isolated from the wine, showing a 50% and 60% reduction in tumor growth on day 33, respectively. Analysis of gene expression showed that genes such as CDK2, FAS, LEF1, PRKCE, and PTGS2, belonging to the NFkappaB, phospholipase C, and calcium signaling pathways, were down-regulated in tumors that developed in grape polyphenol-treated mice. Several genes related to cell cycle regulation, such as CDK5RAP1, RBBP8, and SERTAD1, were up-regulated in these tumors. Changes in the expression of these genes were less pronounced in tumors of wine polyphenol-treated mice. The study highlights the potential influences of dietary polyphenolic components on gene expression in estrogen receptor-negative tumors and its relation to inhibition of tumor growth.

Use of conventional and -omics based methods for health claims of dietary antioxidants: a critical overview

This article describes the principles and limitations of methods used to investigate reactive oxygen species (ROS) protective properties of dietary constituents and is aimed at providing a better understanding of the requirements for science based health claims of antioxidant (AO) effects of foods. A number of currently used biochemical measurements aimed of determining the total antioxidant capacity and oxidised lipids and proteins are carried out under unphysiological conditions and are prone to artefact formation. Probably the most reliable approaches are measurements of isoprostanes as a parameter of lipid peroxidation and determination of oxidative DNA damage. Also the design of the experimental models has a strong impact on the reliability of AO studies: the common strategy is the identification of AO by in vitro screening with cell lines. This approach is based on the assumption that protection towards ROS is due to scavenging, but recent findings indicate that activation of transcription factors which regulate genes involved in antioxidant defence plays a key role in the mode of action of AO. These processes are not adequately represented in cell lines. Another shortcoming of in vitro experiments is that AO are metabolised in vivo and that most cell lines are lacking enzymes which catalyse these reactions. Compounds with large molecular configurations (chlorophylls, anthocyans and polyphenolics) are potent AO in vitro, but weak or no effects were observed in animal/human studies with realistic doses as they are poorly absorbed. The development of -omics approaches will improve the scientific basis for health claims. The evaluation of results from microarray and proteomics studies shows that it is not possible to establish a general signature of alterations of transcription and protein patterns by AO. However, it was shown that alterations of gene expression and protein levels caused by experimentally induced oxidative stress and ROS related diseases can be normalised by dietary AO.

Effects of dietary polyphenols on gene expression in human vascular endothelial cells

Previous studies have shown that consumption of fruit and vegetables plays a role in preventing the onset of CVD. These beneficial effects have been linked to the presence of polyphenolic compounds in plant-derived foods and their antioxidant capacity. It has been hypothesised that polyphenols may also have a direct effect on vascular endothelial cell growth and the expression of genes involved in angiogenesis and other roles of the endothelium. Previous studies in this area have tended to use concentrations of polyphenols that are supraphysiological (1-100 microm). The effects of more physiological concentrations (0.1 microm) of various individual polyphenols on gene expression were therefore investigated in cultured human umbilical vein endothelial cells (HUVEC) using both microarray and quantitative RT-PCR methodologies. Treatment of HUVEC with ferulic acid, quercetin or resveratrol (0.1 microm) resulted in changes to gene expression that for the three treatments amounted to significant (>2-fold) down-regulation of the expression of 363 genes and significant (>2-fold) up-regulation of 233 genes of the 10 000 genes present on the microarray. The majority of these genes were affected by resveratrol. Quantitative RT-PCR studies indicated that resveratrol (0.1 microm) significantly increased the expression of the gene encoding endothelial NO synthase (eNOS), which synthesises the vasodilator molecule NO, and both resveratrol and quercetin decreased expression of the potent vasoconstrictor, endothelin-1 (ET-1), while ferulic acid had no effect. The effects of resveratrol (0.1 microm) were also investigated when HUVEC were under oxidative stress following treatment with H2O2 (0-50 microm), which dose-dependently increased expression of eNOS and ET-1. Resveratrol stimulated eNOS mRNA in the absence of H2O2 and still allowed the increase with H2O2, but the effects were not additive. In contrast, resveratrol blocked the stimulatory effect of H2O2 on ET-1 expression. Hence, resveratrol has potent effects at a physiological concentration (0.1 microm) that would be expected to result in vasodilation and therefore help reduce blood pressure and the risk of CVD.

A role for the aryl hydrocarbon receptor in mammary gland tumorigenesis

The aryl hydrocarbon receptor (AhR) is an evolutionarily conserved transcription factor bound and activated by ubiquitous environmental pollutants. Historically, the AhR has been studied for its transcriptional regulation of genes encoding cytochrome P450 enzymes, which metabolize many of these chemicals into mutagenic and toxic intermediates. However, recent studies demonstrate that the AhR plays an important role in the biology of several cell types in the absence of environmental chemicals. Here, this paradigm shift is discussed in the context of a putative role for the AhR in mammary gland tumorigenesis. Data demonstrating high levels of constitutively active AhR in mammary tumors are summarized. Particular focus is placed on the likelihood that the AhR contributes to ongoing mammary tumor cell growth and on the possibility that the AhR inhibits apoptosis while promoting transition to an invasive, metastatic phenotype. A working model is proposed that may help explain the sometimes contradictory outcomes observed after AhR manipulation and that serves as a blueprint for the design of therapeutics which target the AhR in breast cancer. The theme that malignant cells reveal the functions for which the AhR has been evolutionarily conserved is presented throughout this discussion.

The Tumor Suppressor Activity of the Lysyl Oxidase Propeptide Reverses the Invasive Phenotype of Her-2/neu–Driven Breast Cancer

Expression of the lysyl oxidase gene (LOX) was found to inhibit the transforming activity of the ras oncogene in NIH 3T3 fibroblasts and was hence named the ras recision gene (rrg). Lysyl oxidase (LOX) is synthesized and secreted as a 50-kDa inactive proenzyme (Pro-LOX), which is processed by proteolytic cleavage to a functional 32-kDa enzyme and an 18-kDa propeptide (LOX-PP). Recently, the ras recision activity of the LOX gene in NIH 3T3 cells was mapped to its propeptide region. Here, we show for the first time that LOX-PP inhibits transformation of breast cancer cells driven by Her-2/neu, an upstream activator of Ras. LOX-PP expression in Her-2/neu-driven breast cancer cells in culture suppressed Akt, extracellular signal-regulated kinase, and nuclear factor-kappaB activation. Her-2/neu-induced epithelial to mesenchymal transition was reverted by LOX-PP, as judged by reduced levels of Snail and vimentin; up-regulation of E-cadherin, gamma-catenin, and estrogen receptor alpha; and decreased ability to migrate or to form branching colonies in Matrigel. Furthermore, LOX-PP inhibited Her-2/neu tumor formation in a nude mouse xenograft model. Thus, LOX-PP inhibits signaling cascades induced by Her-2/neu that promote a more invasive phenotype and may provide a novel avenue for treatment of Her-2/neu-driven breast carcinomas.