The role of tamoxifen in the treatment and prevention of breast cancer

Tamoxifen upregulates the peroxisomal β-oxidation enzyme Enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase ameliorating hepatic lipid accumulation in mice

Tamoxifen is an estrogen receptor modulator that has been reported to alleviate hepatic lipid accumulation in mice, but the mechanism is still unclear. Peroxisome fatty acid β-oxidation is the main metabolic pathway for the overload of long-chain fatty acids. As long-chain fatty acids are a cause of hepatic lipid accumulation, the activation of peroxisome fatty acid β-oxidation might be a novel therapeutic strategy for metabolic associated fatty liver disease. In this study, we investigated the mechanism of tamoxifen against hepatic lipid accumulation based on the activation of peroxisome fatty acid β-oxidation. Tamoxifen reduced liver long-chain fatty acids and relieved hepatic lipid accumulation in high fat diet mice without sex difference. In vitro, tamoxifen protected primary hepatocytes against palmitic acid-induced lipotoxicity. Mechanistically, the RNA-sequence of hepatocytes isolated from the liver revealed that peroxisome fatty acid β-oxidation was activated by tamoxifen. Protein and mRNA expression of enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase were significantly increased in vivo and in vitro. Small interfering RNA enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase in primary hepatocytes abolished the therapeutic effects of tamoxifen in lipid accumulation. In conclusion, our results indicated that tamoxifen could relieve hepatic lipid accumulation in high fat diet mice based on the activation of enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase-mediated peroxisome fatty acids β-oxidation.

Frontal Fibrosing Alopecia and Reproductive Health: Assessing the Role of Sex Hormones in Disease Development

Frontal Fibrosing Alopecia (FFA) is a distinctive form of cicatricial alopecia characterized by gradual hairline recession, predominantly affecting postmenopausal individuals, thus implying a potential hormonal origin. This narrative review, spanning 2000 to 2023, delves into PubMed literature, focusing on the menopausal and hormonal status of women with FFA. The objective is to unravel the intricate nature of FFA and its plausible associations with hormonal dysregulations in women. While menopause remains a pivotal demographic characteristic linked to FFA, existing data suggest that its hormonal imbalances may not fully account for the development of FFA. Conversely, substantial evidence indicates a strong association between a reduction in fertile years, particularly through surgical interventions leading to an abrupt hormonal imbalance, and FFA in women. Additionally, exposure to hormone replacement therapy or oral contraceptives has shown varying degrees of association with FFA. Gynecologists should maintain a heightened awareness regarding the ramifications of their interventions and their pivotal role in overseeing women's fertility, recognizing the potential influence on the progression of FFA. The recurrent theme of hormonal disruption strongly implies a causal connection between alterations in sex hormones and FFA in women. Nevertheless, this relationship's extent and underlying mechanisms remain subjects of ongoing debate.

Single Inhibitors versus Dual Inhibitors: Role of HDAC in Cancer

Due to the multimodal character of cancer, inhibition of two targets simultaneously by a single molecule is a beneficial and effective approach against cancer. Histone deacetylase (HDAC) was widely investigated as a novel category of anticancer drug targets due to its crucial role in various biological processes like cell-proliferation, metastasis, and apoptosis. Numerous HDAC inhibitors such as vorinostat and panobinostat are clinically approved but have limited usage due to their low efficacy, nonselectivity, drug resistance, and toxicity. Therefore, HDACs with a dual targeting ability have attracted great attention. The strategy of combining a HDAC inhibitor with other antitumor agents has been proved advantageous for combating the nonselectivity and drug resistivity problems associated with single-target drugs. Henceforth, we have highlighted dual-targeting inhibitors to target HDAC along with topoisomerase, receptor tyrosine kinase inhibitors, and the zeste homolog 2 enzyme. Our Review mainly focuses on the impact of the substituent effect along with the linker variation of well-known HDAC-inhibitor-conjugated anticancer drugs.

Pharmacokinetics of Tamoxifen and Its Major Metabolites and the Effect of the African Ancestry Specific CYP2D6*17 Variant on the Formation of the Active Metabolite, Endoxifen

Tamoxifen (TAM) is widely used in the treatment of hormone receptor-positive breast cancer. TAM is metabolized into the active secondary metabolite endoxifen (ENDO), primarily by CYP2D6. We aimed to investigate the effects of an African-specific CYP2D6 variant allele, CYP2D6*17, on the pharmacokinetics (PK) of TAM and its active metabolites in 42 healthy black Zimbabweans. Subjects were grouped based on CYP2D6 genotypes as CYP2D6*1/*1 or *1/*2 or *2/*2 (CYP2D6*1 or *2), CYP2D6*1/*17 or 2*/*17, and CYP2D6*17/*17. PK parameters for TAM and three metabolites were determined. The pharmacokinetics of ENDO showed statistically significant differences among the three groups. The mean ENDO AUC_0-∞ in CYP2D6*17/*17 subjects was 452.01 (196.94) h·*ng/mL, and the AUC0-∞ in CYP2D6*1/*17 subjects was 889.74 h·ng/mL, which was 5-fold and 2.8-fold lower than in CYP2D6*1 or *2 subjects, respectively. Individuals who were heterozygous or homozygous for CYP2D6*17 alleles showed a 2- and 5-fold decrease in Cmax, respectively, compared to the CYP2D6*1 or *2 genotype. CYP2D6*17 gene carriers have significantly lower ENDO exposure levels than CYP2D6*1 or *2 gene carriers. Pharmacokinetic parameters of TAM and the two primary metabolites, N-desmethyl tamoxifen (NDT) and 4-hydroxy tamoxifen (4OHT), did not show any significant difference in the three genotype groups. The African-specific CYP2D6*17 variant had effects on ENDO exposure levels that could potentially have clinical implications for patients homozygous for this variant.

Sparse canonical correlation to identify breast cancer related genes regulated by copy number aberrations

BACKGROUND

Copy number aberrations (CNAs) in cancer affect disease outcomes by regulating molecular phenotypes, such as gene expressions, that drive important biological processes. To gain comprehensive insights into molecular biomarkers for cancer, it is critical to identify key groups of CNAs, the associated gene modules, regulatory modules, and their downstream effect on outcomes.

METHODS

In this paper, we demonstrate an innovative use of sparse canonical correlation analysis (sCCA) to effectively identify the ensemble of CNAs, and gene modules in the context of binary and censored disease endpoints. Our approach detects potentially orthogonal gene expression modules which are highly correlated with sets of CNA and then identifies the genes within these modules that are associated with the outcome.

RESULTS

Analyzing clinical and genomic data on 1,904 breast cancer patients from the METABRIC study, we found 14 gene modules to be regulated by groups of proximally located CNA sites. We validated this finding using an independent set of 1,077 breast invasive carcinoma samples from The Cancer Genome Atlas (TCGA). Our analysis of 7 clinical endpoints identified several novel and interpretable regulatory associations, highlighting the role of CNAs in key biological pathways and processes for breast cancer. Genes significantly associated with the outcomes were enriched for early estrogen response pathway, DNA repair pathways as well as targets of transcription factors such as E2F4, MYC, and ETS1 that have recognized roles in tumor characteristics and survival. Subsequent meta-analysis across the endpoints further identified several genes through the aggregation of weaker associations.

CONCLUSIONS

Our findings suggest that sCCA analysis can aggregate weaker associations to identify interpretable and important genes, modules, and clinically consequential pathways.

Cancer therapy's impact on lipid metabolism: Mechanisms and future avenues

Atherosclerotic cardiovascular disease is a growing threat among cancer patients. Not surprisingly, cancer-targeting therapies have been linked to metabolic dysregulation including changes in local and systemic lipid metabolism. Thus, tumor development and cancer therapeutics are intimately linked to cholesterol metabolism and may be a driver of increased cardiovascular morbidity and mortality in this population. Chemotherapeutic agents affect lipid metabolism through diverse mechanisms. In this review, we highlight the mechanistic and clinical evidence linking commonly used cytotoxic therapies with cholesterol metabolism and potential opportunities to limit atherosclerotic risk in this patient population. Better understanding of the link between atherosclerosis, cancer therapy, and cholesterol metabolism may inform optimal lipid therapy for cancer patients and mitigate cardiovascular disease burden.

Immune-Related Protein Interaction Network in Severe COVID-19 Patients toward the Identification of Key Proteins and Drug Repurposing

Coronavirus disease 2019 (COVID-19) is still an active global public health issue. Although vaccines and therapeutic options are available, some patients experience severe conditions and need critical care support. Hence, identifying key genes or proteins involved in immune-related severe COVID-19 is necessary to find or develop the targeted therapies. This study proposed a novel construction of an immune-related protein interaction network (IPIN) in severe cases with the use of a network diffusion technique on a human interactome network and transcriptomic data. Enrichment analysis revealed that the IPIN was mainly associated with antiviral, innate immune, apoptosis, cell division, and cell cycle regulation signaling pathways. Twenty-three proteins were identified as key proteins to find associated drugs. Finally, poly (I:C), mitomycin C, decitabine, gemcitabine, hydroxyurea, tamoxifen, and curcumin were the potential drugs interacting with the key proteins to heal severe COVID-19. In conclusion, IPIN can be a good representative network for the immune system that integrates the protein interaction network and transcriptomic data. Thus, the key proteins and target drugs in IPIN help to find a new treatment with the use of existing drugs to treat the disease apart from vaccination and conventional antiviral therapy.

Discovery of Proteins Responsible for Resistance to Three Chemotherapy Drugs in Breast Cancer Cells Using Proteomics and Bioinformatics Analysis

Chemoresistance is a daunting obstacle to the effective treatment of breast cancer patients receiving chemotherapy. Although the mechanism of chemotherapy drug resistance has been explored broadly, the precise mechanism at the proteome level remains unclear. Especially, comparative studies between widely used anticancer drugs in breast cancer are very limited. In this study, we employed proteomics and bioinformatics approaches on chemoresistant breast cancer cell lines to understand the underlying resistance mechanisms that resulted from doxorubicin (DR), paclitaxel (PR), and tamoxifen (TAR). In total, 10,385 proteins were identified and quantified from three TMT 6-plex and one TMT 10-plex experiments. Bioinformatics analysis showed that Notch signaling, immune response, and protein re-localization processes were uniquely associated with DR, PR, and TAR resistance, respectively. In addition, proteomic signatures related to drug resistance were identified as potential targets of many FDA-approved drugs. Furthermore, we identified potential prognostic proteins with significant effects on overall survival. Representatively, PLXNB2 expression was associated with a highly significant increase in risk, and downregulation of ACOX3 was correlated with a worse overall survival rate. Consequently, our study provides new insights into the proteomic aspects of the distinct mechanisms underlying chemoresistance in breast cancer.

Hyaluronic acid-coated chitosan nanoparticles as targeted-carrier of tamoxifen against MCF7 and TMX-resistant MCF7 cells

Tamoxifen (TMX) is used to treat hormone-receptor-positive breast cancers at early stages. This research aimed to assess the potential of NPs in targeted delivery of TMX against MCF7 and TMX-resistant MCF7 breast cancer cell lines. For this purpose, a targeted delivery system including chitosan NPs coated with hyaluronic acid (HA-CS NPs) was created and examined in vitro. Chitosan NPs were first fabricated and loaded with TMX using the ionic-gelation method to prepare a drug-delivery system. Then, TMX-loaded CS NPs were coated by crosslinking the amino groups of chitosan to the carboxylic group of hyaluronic acid. The developed TMX delivery system was then optimized and characterized for particle fabrication, drug release, and targeting against cancer cells. The HA-CS particle size was 210 nm and its zeta potential was +25 mv. The encapsulation efficiency of TMX in NPs was 55%. TMX released from the NPs in acidic pH (5-6) was higher than the physiological pH (7.4). The cytotoxic effect of TMX-loaded HA-CS NPs on MCF7 and TMX-resistant MCF7 cells was significantly higher than TMX-loaded CS NPs and free drug. The findings confirmed the significant suppressive impact of TMX-loaded HA-CS NPs on MCF7 and TMX-resistant MCF7 cancer cells compared to the TMX-loaded CS NPs and free TMX. Graphical abstract.

Chitosan: A versatile bio-platform for breast cancer theranostics

Breast cancer is considered one of the utmost neoplastic diseases globally, with a high death rate of patients. Over the last decades, many approaches have been studied to early diagnose and treat it, such as chemotherapy, hormone therapy, immunotherapy, and MRI and biomarker tests; do not show the optimal efficacy. These existing approaches are accompanied by severe side effects, thus recognizing these challenges, a great effort has been done to find out the new remedies for breast cancer. Main finding: Nanotechnology opened a new horizon to the treatment of breast cancer. Many nanoparticulate platforms for the diagnosis of involved biomarkers and delivering antineoplastic drugs are under either clinical trials or just approved by the Food and Drug Administration (FDA). It is well known that natural phytochemicals are successfully useful to treat breast cancer because these natural compounds are safer, available, cheaper, and have less toxic effects. Chitosan is a biocompatible and biodegradable polymer. Further, it has outstanding features, like chemical functional groups that can easily modify our interest with an exceptional choice of promising applications. Abundant studies were directed to assess the chitosan derivative-based nanoformulation's abilities in delivering varieties of drugs. However, the role of chitosan in diagnostics and theranostics not be obligated. The present servey will discuss the application of chitosan as an anticancer drug carrier such as tamoxifen, doxorubicin, paclitaxel, docetaxel, etc. and also, its role as a theranostics (i.e. photo-responsive and thermo-responsive) moieties. The therapeutic and theranostic potential of chitosan in cancer is promising and it seems that to have a good potential to get to the clinic.

LncRNA MORT (ZNF667-AS1) in Cancer-Is There a Possible Role in Gynecological Malignancies?

Gynecological cancers (GCs) are currently among the major threats to female health. Moreover, there are different histologic subtypes of these cancers, which are defined as ‘rare’ due to an annual incidence of <6 per 100,000 women. The majority of these tend to be associated with a poor prognosis. Long non-coding RNAs (lncRNAs) play a critical role in the normal development of organisms as well as in tumorigenesis. LncRNAs can be classified into tumor suppressor genes or oncogenes, depending on their function within the cellular context and the signaling pathways in which they are involved. These regulatory RNAs are potential therapeutic targets for cancer due to their tissue and tumor specificity. However, there still needs to be a deeper understanding of the mechanisms by which lncRNAs are involved in the regulation of numerous biological functions in humans, both in normal health and disease. The lncRNA Mortal Obligate RNA Transcript (MORT; alias ZNF667-AS1) has been identified as a tumor-related lncRNA. ZNF667-AS1 gene, located in the human chromosome region 19q13.43, has been shown to be silenced by DNA hypermethylation in several cancers. In this review, we report on the biological functions of ZNF667-AS1 from recent studies and describe the regulatory functions of ZNF667-AS1 in human disease, including cancer. Furthermore, we discuss the emerging insights into the potential role of ZNF667-AS1 as a biomarker and novel therapeutic target in cancer, including GCs (ovarian, cervical, and endometrial cancers).

Association of single nucleotide polymorphisms of cytochrome P450 enzymes with experience of vasomotor, vaginal and musculoskeletal symptoms among breast cancer patients: a systematic review

Background

Adjuvant endocrine therapies are known to induce undesirable adverse effects such as vasomotor, vaginal and musculoskeletal symptoms among breast cancer patients. Drugs used in these therapies are often metabolised by cytochrome P450 (CYP) enzymes, in which their metabolising activities can be modified by single nucleotide polymorphisms (SNP) in CYP genes and CYP genotypes. This review aims to explore whether SNPs or genotypes of CYP are associated with the occurrence, frequency and severity of vasomotor, vaginal and musculoskeletal symptoms in breast cancer patients on adjuvant endocrine therapies.

Methods

A literature review was conducted using five electronic databases, resulting in the inclusion of 14 eligible studies, and their findings were presented narratively. Selected items from the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist were used for critical appraisal of the reporting quality of the included studies.

Results

Most of the included studies showed that SNPs or genotypes of CYP that modify its metabolising activity have no effect on the occurrence, frequency or severity of vasomotor symptoms, including hot flashes. One study showed no correlation of these genetic variations in CYP with musculoskeletal symptoms, and no data were available on the association between such genetic variations and vaginal symptoms.

Conclusions

Overall, genetic variations in CYP have no effect on the experience of hot flashes among breast cancer patients. We recommend exploration of the link between the active metabolites of chemotherapeutic drugs and the molecules shown to affect the occurrence or severity of hot flashes, and the establishment of the relationship between such genetic variations and patients’ experience of musculoskeletal and vaginal symptoms. Subgroup analyses based on patients’ duration of adjuvant endocrine therapies in such studies are recommended.

Bioinformatics and system biology approach to identify the influences of SARS-CoV-2 infections to idiopathic pulmonary fibrosis and chronic obstructive pulmonary disease patients

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), better known as COVID-19, has become a current threat to humanity. The second wave of the SARS-CoV-2 virus has hit many countries, and the confirmed COVID-19 cases are quickly spreading. Therefore, the epidemic is still passing the terrible stage. Having idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) are the risk factors of the COVID-19, but the molecular mechanisms that underlie IPF, COPD, and CVOID-19 are not well understood. Therefore, we implemented transcriptomic analysis to detect common pathways and molecular biomarkers in IPF, COPD, and COVID-19 that help understand the linkage of SARS-CoV-2 to the IPF and COPD patients. Here, three RNA-seq datasets (GSE147507, GSE52463, and GSE57148) from Gene Expression Omnibus (GEO) is employed to detect mutual differentially expressed genes (DEGs) for IPF, and COPD patients with the COVID-19 infection for finding shared pathways and candidate drugs. A total of 65 common DEGs among these three datasets were identified. Various combinatorial statistical methods and bioinformatics tools were used to build the protein–protein interaction (PPI) and then identified Hub genes and essential modules from this PPI network. Moreover, we performed functional analysis under ontologies terms and pathway analysis and found that IPF and COPD have some shared links to the progression of COVID-19 infection. Transcription factors–genes interaction, protein–drug interactions, and DEGs-miRNAs coregulatory network with common DEGs also identified on the datasets. We think that the candidate drugs obtained by this study might be helpful for effective therapeutic in COVID-19.

A machine learning and network framework to discover new indications for small molecules

Drug repurposing, identifying novel indications for drugs, bypasses common drug development pitfalls to ultimately deliver therapies to patients faster. However, most repurposing discoveries have been led by anecdotal observations (e.g. Viagra) or experimental-based repurposing screens, which are costly, time-consuming, and imprecise. Recently, more systematic computational approaches have been proposed, however these rely on utilizing the information from the diseases a drug is already approved to treat. This inherently limits the algorithms, making them unusable for investigational molecules. Here, we present a computational approach to drug repurposing, CATNIP, that requires only biological and chemical information of a molecule. CATNIP is trained with 2,576 diverse small molecules and uses 16 different drug similarity features, such as structural, target, or pathway based similarity. This model obtains significant predictive power (AUC = 0.841). Using our model, we created a repurposing network to identify broad scale repurposing opportunities between drug types. By exploiting this network, we identified literature-supported repurposing candidates, such as the use of systemic hormonal preparations for the treatment of respiratory illnesses. Furthermore, we demonstrated that we can use our approach to identify novel uses for defined drug classes. We found that adrenergic uptake inhibitors, specifically amitriptyline and trimipramine, could be potential therapies for Parkinson's disease. Additionally, using CATNIP, we predicted the kinase inhibitor, vandetanib, as a possible treatment for Type 2 Diabetes. Overall, this systematic approach to drug repurposing lays the groundwork to streamline future drug development efforts.

Machine Learning Supports Long Noncoding RNAs as Expression Markers for Endometrial Carcinoma

Uterine corpus endometrial carcinoma (UCEC) is the second most common type of gynecological tumor. Several research studies have recently shown the potential of different ncRNAs as biomarkers for prognostics and diagnosis in different types of cancers, including UCEC. Thus, we hypothesized that long noncoding RNAs (lncRNAs) could serve as efficient factors to discriminate solid primary (TP) and normal adjacent (NT) tissues in UCEC with high accuracy. We performed an in silico differential expression analysis comparing TP and NT from a set of samples downloaded from the Cancer Genome Atlas (TCGA) database, targeting highly differentially expressed lncRNAs that could potentially serve as gene expression markers. All analyses were performed in R software. The receiver operator characteristics (ROC) analyses and both supervised and unsupervised machine learning indicated a set of 14 lncRNAs that may serve as biomarkers for UCEC. Functions and putative pathways were assessed through a coexpression network and target enrichment analysis.

Endocrine and Targeted Therapy for Hormone-Receptor-Positive, HER2-Negative Advanced Breast Cancer: Insights to Sequencing Treatment and Overcoming Resistance Based on Clinical Trials

Background: Advanced hormone-receptor positive HER2 negative breast cancer is a common and a very heterogeneous disease. Hormone therapy is the main first line treatment of choice, given alone or in combination with other agents that have shown to improve patient outcomes, Nevertheless, treatment remains generally palliative rather than curative. Sequencing of such treatment remains challenging, especially with resurgence of variable resistance patterns. Multiple attempts have been made to overcome resistance and improve patient survival, yet resistance remains not very well understood and metastatic cancer remains a disease with dismal prognosis.

Methods: In this paper, we searched pubmed database as well as local and international meetings for all studies discussing advanced and metastatic hormone-receptor-positive, her2-negative breast cancer, hormonal treatment, resistance to hormonal treatment, mechanism of resistance, and means to overcome such resistance.

Conclusion: There does not exist an optimal treatment sequence for hormone-receptor-positive, her2-negative advanced breast cancer. However, after review of literature, a reasonable approach may be starting with tamoxifen, aromatase inhibitors, or fulvestrant in absence of visceral crisis, in addition to ensuring adequate ovarian function suppression in pre/peri-menopausal women. Aromatase inhibitors and fulvestrant seem to be superior. Resistance to such agents is increasing, mostly attributed to genetic and molecular changes. Multiple modalities are addressed to overcome such resistance including use of CKD4/6 inhibitors, mTOR inhibitors and PI3K inhibitors in addition to other agents under study, all with promising results. CDK4/6 inhibitors work best when used in frontline setting. Finally, treatment of breast cancer remains a growing field, and more studies are to be awaited.

Emerging roles of gap junction proteins connexins in cancer metastasis, chemoresistance and clinical application

Connexin, a four-pass transmembrane protein, contributes to assembly of gap junctions among neighboring cells and thus facilitates gap junctional intercellular communication (GJIC). Traditionally, the roles of connexins were thought to mediate formation of hemichannels and GJIC assembly for transportation of ions and small molecules. Many studies have observed loss of GJIC, due to reduced expression or altered cytoplasmic localization of connexins, in primary tumor cells. Connexins are generally considered tumor-suppressive. However, recent studies of clinical samples suggested a different role of connexins in that expression levels and membrane localization of connexins, including Connexin 43 (Cx43, GJA1) and Connexin 26 (Cx26, GJB2), were found to be enhanced in metastatic lesions of cancer patients. Cx43- and Cx26-mediated GJIC was found to promote cancer cell migration and adhesion to the pulmonary endothelium. Regulatory circuits involved in the induction of connexins and their functional effects have also been reported in various types of cancer. Connexins expressed in stromal cells were correlated with metastasis and were implicated in regulating metastatic behaviors of cancer cells. Recent studies have revealed that connexins can contribute to cellular phenotypes via multiple ways, namely 1) GJIC, 2) C-terminal tail-mediated signaling, and 3) cell-cell adhesion during gap junction formation. Both expression levels and the subcellular localization could participate determining the functional roles of connexins in cancer. Compounds targeting connexins were thus tested as potential therapeutics intervening metastasis or chemoresistance. This review focuses on the recent findings in the correlation between the expression of connexins and patients’ prognosis, their roles in metastasis and chemoresistance, as well as the implications and concerns of using connexin-targeting drugs as anti-metastatic therapeutics. Overall, connexins may serve as biomarkers for cancer prognosis and as therapeutic targets for intervening metastasis and chemoresistance.

The Effect of Flaxseed in Breast Cancer: A Literature Review

Breast cancer is one of the most common cancers and the second most responsible for cancer mortality worldwide. In 2014, in Portugal approximately 27,200 people died of cancer, of which 1,791 were women with breast cancer. Flaxseed has been one of the most studied foods, regarding possible relations to breast cancer, though mainly in experimental studies in animals, yet in few clinical trials. It is rich in omega-3 fatty acids, α-linolenic acid, lignan, and fibers. One of the main components of flaxseed is the lignans, of which 95% are made of the predominant secoisolariciresinol diglucoside (SDG). SDG is converted into enterolactone and enterodiol, both with antiestrogen activity and structurally similar to estrogen; they can bind to cell receptors, decreasing cell growth. Some studies have shown that the intake of omega-3 fatty acids is related to the reduction of breast cancer risk. In animal studies, α-linolenic acids have been shown to be able to suppress growth, size, and proliferation of cancer cells and also to promote breast cancer cell death. Other animal studies found that the intake of flaxseed combined with tamoxifen can reduce tumor size to a greater extent than taking tamoxifen alone. Additionally, some clinical trials showed that flaxseed can have an important role in decreasing breast cancer risk, mainly in postmenopausal women. Further studies are needed, specifically clinical trials that may demonstrate the potential benefits of flaxseed in breast cancer.

Lippia origanoides extract induces cell cycle arrest and apoptosis and suppresses NF-κB signaling in triple-negative breast cancer cells

Treatments targeting hormone receptors typically fail to provide a positive clinical outcome against triple-negative breast cancers (TNBC), which lack expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her2/neu). Towards identifying viable treatments for aggressive breast cancer, we have tested an extract of the tropical plant Lippia origanoides (LOE) on TNBC and normal cells lines to uncover its potential anticancer effects. Treatment with LOE reduced TNBC cell viability in a dose-dependent manner to a greater extent than in normal mammary epithelial MCF10A cells. In MDA-MB-231 cells, LOE was found to halt the cell cycle in the G0/G1 phase via cyclin D1 and cIAP2 regulation, and induce apoptosis without promoting necrosis via caspase-8/-3 and PARP cleavage. Constitutive nuclear factor-κB (NF-κB) signaling has been shown to contribute to the heightened inflammatory state and survival in TNBC cells. Herein, we also provide evidence that LOE inhibits NF-κB signaling by reducing RIP1 protein levels in MDA-MB-231 cells. These studies reveal that LOE suppresses key features of the progression of aggressive breast cancer cells and provides a basis for further definition of its underlying mechanisms of action and anticancer potential.

Synthesis and Biological Evaluations of Ring Substituted Tetrahydroisoquinolines (THIQs) as Anti-Breast Cancer Agents

Breast cancer is a leading cause of mortality among women, resulting in more than half a million deaths worldwide every year. Although chemotherapeutic drugs remain the main stay of cancer treatment, it is observed that toxicity to normal cells poses a limitation to their therapeutic values. Moreover, the patient recovery rate from advanced breast cancer by chemotherapy is still unacceptably low. Tetrahydroisoqinoline derivatives (THIQs) were reported to act as selective subtype estrogen receptor antagonists/agonists and may serve as potential therapeutic agents for breast cancer. In continuation of previous work we systematically synthesized and characterized the tetrahydroisoquinoline (THIQs) analogs. In-vitro antiproliferative activity of new substituted tetrahydroisoquinoline analogs were evaluated against human ER (+) MCF-7 (breast), ER (−) MDA-MB-231 (breast) and Ishikawa (endometrial) cancer cell lines using the CellTiter-Glo luminescent cell viability assay. The most active compounds obtained in this study were 2b, 2i, and 3 g as demonstrated by their activity (IC₅₀=0.2 μg/mL, 0.08 μg/mL; 0.61 μg/mL, 0.09 μg/mL; 0.25 μg/mL, 0.11 μg/mL) against MCF-7 and Ishikawa cell lines respectively, in comparison to Tamoxifen activity (IC₅₀=3.99 μg/mL, 7.87 μg/ml). The newly synthesized molecules were docked in the active sites of the ER-α (PDB: 3ERT), ER-β (PDB: 1QKN) and alpha-beta tubulin taxol complex (1JFF) crystal structures to determine the probable binding modes (bioactive conformations) of the active compounds.

Development of new therapy for canine mammary cancer with recombinant measles virus

Oncolytic virotherapy is a promising treatment strategy for cancer. We previously generated a recombinant measles virus (rMV-SLAMblind) that selectively uses a poliovirus receptor-related 4 (PVRL4/Nectin4) receptor, but not signaling lymphocyte activation molecule (SLAM). We demonstrated that the virus exerts therapeutic effects against human breast cancer cells. Here, we examined the applicability of rMV-SLAMblind to treating canine mammary cancers (CMCs). We found that the susceptibilities of host cells to rMV-SLAMblind were dependent on canine Nectin-4 expression. Nectin-4 was detected in four of nine CMC cell lines. The rMV-SLAMblind efficiently infected those four Nectin-4-positive cell lines and was cytotoxic for three of them (CF33, CHMm, and CTBm). In vivo experiment showed that the administration of rMV-SLAMblind greatly suppressed the progression of tumors in mice xenografted with a CMC cell line (CF33). Immunohistochemistry revealed that canine Nectin-4 was expressed in 45% of canine mammary tumors, and the tumor cells derived from one clinical specimen were efficiently infected with rMV-SLAMblind. These results suggest that rMV-SLAMblind infects CMC cells and displays antitumor activity in vitro, in xenografts, and ex vivo. Therefore, oncolytic virotherapy with rMV-SLAMblind can be a novel method for treating CMCs.

Leishmania is not prone to develop resistance to tamoxifen

Tamoxifen, an antineoplastic agent, is active in vitro and in vivo against the parasitic protozoa Leishmania. As part of our efforts to unravel this drug's mechanisms of action against the parasite and understand how resistance could arise, we tried to select tamoxifen-resistant Leishmania amazonensis. Three different strategies to generate tamoxifen resistant mutants were used: stepwise increase in drug concentration applied to promastigote cultures, chemical mutagenesis followed by drug selection and treatment of infected mice followed by selection of amastigotes. For amastigote selection, we employed a method with direct plating of parasites recovered from lesions into semi-solid media. Tamoxifen resistant parasites were not rescued by any of these methods. Miltefosine was used as a control in selection experiments and both stepwise selection and chemical mutagenesis allowed successful isolation of miltefosine resistant mutants. These findings are consistent with a multi-target mode of action to explain tamoxifen's leishmanicidal properties. Considering that drug resistance is a major concern in anti-parasitic chemotherapy, these findings support the proposition of using tamoxifen as a partner in drug combination schemes for the treatment of leishmaniasis.

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Tamoxifen is effective in the treatment of cutaneous and visceral leishmaniasis.

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Resistance to tamoxifen was not found in promastigotes upon mutagenesis/selection.

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Resistance to tamoxifen was not detected in amastigotes after in vivo selection.

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Tamoxifen may be a good partner in drug combination schemes for leishmaniasis.

Synthesis and biological activity of 3-N-substituted estrogen derivatives as breast cancer agents

3-N-substituted-estrogen derivatives were synthesized and characterized. Their antiproliferative activities against human ER (+) MCF-7 (Breast), ER (-) MDA-MB-231 (breast) and Ishikawa (endometrial) cancer cell lines were determined after 72 hours drug exposure employing CellTiter-Glo assay at concentrations ranging from (0.01-100,000 nM). The antiproliferative activities of these compounds were compared to tamoxifen (TAM), 4-hydroxytamoxifen (4-OHT, active metabolite of tamoxifen) and raloxifene (RAL). In vitro results indicated that compound 5 (IC50 = 12 µM) displayed comparable antiproliferative activity against MDA-MB 231 cell line; while compounds 6, 7 and 13 (IC50 = 12 µM) displayed higher activity against MCF-7 and Ishikawa cell lines, in comparison to TAM activity (19-33 µM).

Synthesis and Pharmacological Evolution of Tetrahydroisoquinolines as Anti Breast Cancer Agents

Breast cancer is leading cause of mortality among women, resulting in more than half a million deaths worldwide each year. Unfortunately, the recovery rate of advanced breast cancer by current available drug treatment is till unacceptably low. Chemotherapy is the main stay of cancer treatment and most of the drugs cause general toxicity to any non-proliferating cells, which can severely limit the therapeutic values of these drugs. Tetrahydroisoqinoline derivatives (THIQs) were identified as subtype selective estrogen receptor antagonists/agonists hence, potential therapeutic agents for breast cancer. Substituted THIQs were synthesized and well characterized. Antiproliferative activity against human ER (+) MCF-7 (Breast), ER(-) MDA-MB-231 (breast) and Ishikawa (endometrial) cancer cell lines were studied after 72 hours drug exposure employing CellTiter-Glo assay at concentrations ranging from 0.01-100,000 nM. The activities of these compounds were compared with Tamoxifen (TAM). In-vitro results indicated that most of the compounds showed better activity than TAM. The most active compounds obtained in this study were 6a, 6b, 6d and 6j (IC₅₀=0.63, 0.23; 0.93, 0.21; 043, 0.01; 0.7, 0.02 μg/ml) against MCF-7 and Ishikawa cell lines, in comparison to Tamoxifen activity (IC₅₀=5.14, 4.55 μg/ml). The newly synthesized molecules were docked in the active sites of the ER-α (PDB: 3ERT) and ER-β (PDB: 3ERT) crystal structures and probable binding modes of this class of molecules were determined.

Metallocenes as Target Specific Drugs for Cancer Treatment

The application use of organometallic compounds into the cancer research was established in the late 1970s by Köpf-Maeir and Köpf. This new research area has been developed for the past thirty years. In the early 1980s, Jaouen and coworkers recognized the potential application of organometallic compounds vectorized with pendant groups that can deliver the drug to certain specific receptors. This is what is called nowdays Target Specific Drugs. This review will focus on metallocenes vectorized with steroids derivatives of hormones, nonsteroidal and selective endrocrine modulator.

Loss of ERbeta expression as a common step in estrogen-dependent tumor progression

The characterization of estrogen receptor beta (ERbeta) brought new insight into the mechanisms underlying estrogen signaling. Estrogen induction of cell proliferation is a crucial step in carcinogenesis of gynecologic target tissues, and the mitogenic effects of estrogen in these tissues (such as breast, endometrium and ovary) are well documented both in vitro and in vivo. There is also an emerging body of evidence that colon and prostate cancer growth is influenced by estrogens. In all of these tissues, most studies have shown decreased ERbeta expression in cancer as compared with benign tumors or normal tissues, whereas ERalpha expression persists. The loss of ERbeta expression in cancer cells could reflect tumor cell dedifferentiation but may also represent a critical stage in estrogen-dependent tumor progression. Modulation of the expression of ERalpha target genes by ERbeta or ERbeta-specific gene induction could explain that ERbeta has a differential effect on proliferation as compared with ERalpha. ERbeta may exert a protective effect and thus constitute a new target for hormone therapy, such as ligand specific activation. The potential distinct roles of ERalpha and ERbeta expression in carcinogenesis, as suggested by experimental and clinical data, are discussed in this review.

Lipidosis induced in rat uteri by high doses of tamoxifen

The anti-estrogenic drug tamoxifen is an amphiphilic cationic compound and might therefore be expected to interfere with intralysosomal catabolism of polar lipids as has been previously reported with several other amphiphilic cationic drugs. The purpose of this study was to investigate whether there is lipidosis induction in the uterus. High oral doses of tamoxifen (100 mg/kg) were administered to 9 adult rats for 6-14 weeks. Their uteri were examined by light and electron microscopy. Lipidosis-like alterations were seen in the glandular epithelia and in the myometrium. The luminal epithelium was most severely affected. The highest degree of intraepithelial change was already observed after a short-term treatment (6 weeks). The results support the previously proposed concept of a relationship between the amphiphilic cationic character of a compound and its ability to cause intralysosomal storage of polar lipids after a high dosage treatment of these drugs in animals.

Tamoxifen inhibits colorectal cancer metastases in the liver: a study in a murine model

Liver metastases account for over 70% of deaths resulting from colorectal carcinoma, with survival rates varying between 6-18 months. At present, surgical resection offers the only hope for a cure, while chemotherapy, focal destructive techniques and selective internal radiation offer palliative care. Tamoxifen, a non-steroidal anti-oestrogen is primarily known for treating oestrogen receptor (ER)-positive breast cancer. Some studies suggest that tamoxifen may have beneficial effects in malignancies other than breast cancer. These inhibitory effects, which have been shown to be independent of the ER, highlight new mechanisms of therapeutic action. Using an intrasplenic animal model we report the efficacy of tamoxifen on experimental liver metastases. In this model, a dimethyl hydrazine-induced colon carcinoma cell suspension is introduced into the portal circulation via the spleen, which results in secondary tumour deposits in the liver in virtually all animals. Tamoxifen was administered at a dose of 1 mg/kg suspended in 1.0% methyl cellulose. The control group received an equal volume of the vehicle. The reagents were administered s.c. on the day of metastases induction and were continued daily over a 4 week period. The effect of tamoxifen on tumour growth was assessed by stereology and bromodeoxyuridine immunohistochemistry at selected time points. Data were assessed by a multiple analysis of variance where P < 0.05 was considered significant. In the control group the volume of metastases increased from 44 +/- 41 mm3 at day 10 to 517 +/- 380 mm3, 1394 +/- 598 mm3 and 2082 +/- 675 mm3 by days 16, 22 and 28, respectively. Daily administration of tamoxifen exerted an inhibitory effect on tumour growth during the first 3 weeks, recording a volume of 421 +/- 299 mm3 by day 22 compared with the control group at that time point (P = 0.00004). The inhibitory effect diminished by the fourth week recording a tumour volume of 1344 +/- 674 mm3 by day 28. Inhibition of tumour growth at day 22 coincides with a reduction of cells in the S phase of the cell cycle. The percentage of brdU-positive nuclear profiles in metastases of tamoxifen-treated mice at 3 weeks was 35.87 +/- 5.60% compared with 48.01 +/- 3.96% in the control group (P = 0.001). These data suggest that tamoxifen has a potent inhibitory action on colorectal liver metastases by exerting an effect on cell proliferation.

PCNA-immunoreactivity in the uterus of rats after treatment with the antiestrogen tamoxifen

We used an antibody to the proliferating cell nuclear antigen (PCNA) to investigate the effect of the long-term administration of tamoxifen on proliferative activity in the uterus of mature rats. Untreated cycling and ovariectomized rats served as controls. The PCNA labelling indices (PI) and the mitotic indices (MI) were estimated for the luminal and glandular epithelium and for the stromal fibroblasts. A strong correlation was found for PI and MI in the luminal and in the glandular epithelium, and a lower, but also significant correlation, for the endometrial stroma cells. Tamoxifen treatment decreased the PI of the luminal epithelial cells and of the stroma as much as ovariectomy. In both of these groups, the proportion of anti-PCNA positive cells in the glandular epithelium was significantly higher than in the luminal epithelium. These data indicate that tamoxifen has a strong antiproliferative effect on the uterus of mature rats, and that this antiestrogenic action is cell type specific.

The incidence of hepatocellular carcinoma in US white women with breast cancer after the introduction of tamoxifen in 1977

It has been hypothesized that hepatocellular carcinoma might be a long-term adverse effect of tamoxifen therapy. Data from nine population-based cancer registries in the United States were used to investigate time trends in the incidence of hepatocellular carcinoma in white women previously diagnosed with invasive breast cancer during 1974-1987 and followed until 1989. Of particular interest were the rates after 1977, the year tamoxifen was licensed by the FDA. Compared to rates in all white women, no increased risk of hepatocellular carcinoma was found in women most likely to have received tamoxifen--those 50 years of age or more at diagnosis of breast cancer and diagnosed after 1977. These results suggest that tamoxifen does not cause a large increase in the incidence of hepatocellular carcinoma within the first decade after use. However, smaller and/or later increases in the risk for hepatocellular carcinoma are possible and warrant continued monitoring of women treated with tamoxifen.

Protective actions of tamoxifen and 4-hydroxytamoxifen against oxidative damage to human low-density lipoproteins: a mechanism accounting for the cardioprotective action of tamoxifen?

Tamoxifen and 4-hydroxytamoxifen protect isolated human low-density lipoproteins (LDLs) against copper-ion-dependent lipid peroxidation: 4-hydroxytamoxifen is more protective than tamoxifen or 17 beta-oestradiol. 4-Hydroxytamoxifen and 17 beta-oestradiol also prevent the increase in the electrophoretic mobility of LDL caused by exposure to copper ions, presumably by protection of the apoprotein B of LDL against oxidative modification. Our observations may help to account for the cardioprotective benefits reported to be associated with tamoxifen therapy and prophylaxis in breast cancer.

Targeted hormone therapy for breast cancer

Large-scale studies now provide relatively clear guidelines for the clinician on antiestrogen treatment in various patient populations and subgroups. Future challenges are to determine whether antiestrogens might be used for prevention, to identify the environmental and genetic causes of breast cancer, and to develop new approaches to this tumor, such as antiprogestins.