Interactions Between Natural Products and Tamoxifen in Breast Cancer: A Comprehensive Literature Review

Citrus polymethoxyflavones degrade estrogen receptor-alpha (ERα) and combine with tamoxifen for the treatment of estrogen receptor-positive breast cancer

Estrogen receptor-positive (ER+) breast cancer seriously endangers the women's physical and mental health worldwide and ER targeting therapy is vital. Here, we found that a citrus polymethoxyflavones (PMFs)-rich hydrolysate (C-H) and its major components (nobiletin and 3-methoxynobiletin) potently degrade ERα protein via the ubiquitin-proteasome pathway, thereby impairing the proliferation of ER+ breast cancer cells. Moreover, our study exhibited that C-H combined with tamoxifen (TAM) inhibited the cell proliferation of ER+ breast cancer in vitro. It was further confirmed that C-H decreased tumor growth of ER+ breast cancer in tumor-bearing 129 mice in vivo and improved the efficacy of tamoxifen. Our study revealed that the citrus PMFs have potential applications as pharmaceutical and healthcare products in breast cancer treatment by targeting ERα protein degradation.

Lactic Acid Bacteria-Derived Postbiotics as Adjunctive Agents in Breast Cancer Treatment to Boost the Antineoplastic Effect of a Conventional Therapeutic Comprising Tamoxifen and a New Drug Candidate: An Aziridine-Hydrazide Hydrazone Derivative

Breast cancer is associated with high mortality and morbidity rates. As about 20-30% of patients exhibiting ER-positive phenotype are resistant to hormonal treatment with the standard drug tamoxifen, finding new therapies is a necessity. Postbiotics, metabolites, and macromolecules isolated from probiotic bacteria cultures have been proven to have sufficient bioactivity to exert prohealth and anticancer effects, making them viable adjunctive agents for the treatment of various neoplasms, including breast cancer. In the current study, postbiotics derived from L. plantarum and L. rhamnosus cultures were assessed on an in vitro breast cancer model as potential adjunctive agents to therapy utilizing tamoxifen and a candidate aziridine-hydrazide hydrazone derivative drug. Cell viability and cell death processes, including apoptosis, were analyzed for neoplastic MCF-7 cells treated with postbiotics and synthetic compounds. Cell cycle progression and proliferation were analyzed by PI-based flow cytometry and Ki-67 immunostaining. Postbiotics decreased viability and triggered apoptosis in MCF-7, modestly affecting the cell cycle and showing a lack of negative impact on normal cell viability. Moreover, they enhanced the cytotoxic effect of tamoxifen and the new candidate drug toward MCF-7, accelerating apoptosis and the inhibition of proliferation. This illustrates postbiotics' potential as natural adjunctive agents supporting anticancer therapy based on synthetic drugs.

Natural products reverse cancer multidrug resistance

Cancer stands as a prominent global cause of death. One of the key reasons why clinical tumor chemotherapy fails is multidrug resistance (MDR). In recent decades, accumulated studies have shown how Natural Product-Derived Compounds can reverse tumor MDR. Discovering novel potential modulators to reduce tumor MDR by Natural Product-Derived Compounds has become a popular research area across the globe. Numerous studies mainly focus on natural products including flavonoids, alkaloids, terpenoids, polyphenols and coumarins for their MDR modulatory activity. Natural products reverse MDR by regulating signaling pathways or the relevant expressed protein or gene. Here we perform a deep review of the previous achievements, recent advances in the development of natural products as a treatment for MDR. This review aims to provide some insights for the study of multidrug resistance of natural products.

Mechanisms of Traditional Chinese medicine/natural medicine in HR-positive Breast Cancer: A comprehensive Literature Review

ETHNOPHARMACOLOGICAL RELEVANCE

With the emergence of endocrine resistance, the survival and good prognosis of HR-positive breast cancer (HR + BC) patients are threatened. As a common complementary and alternative therapy in cancer treatment, traditional Chinese medicine (TCM) has been widely used, and its internal mechanisms have been increasingly explored.

AIM OF THE REVIEW

In this review, the development status and achievements in understanding of the mechanisms related to the anti-invasion and anti-metastasis effects of TCM against HR + BC and the reversal of endocrine drug resistance by TCM in recent years have been summarized to provide ideas for antitumour research on the active components of TCM/natural medicine.

METHODS

We searched the electronic databases PubMed, Web of Science, and China National Knowledge Infrastructure database (CNKI) (from inception to July 2023) with the key words "HR-positive breast cancer" or "HR-positive breast carcinoma", "HR + BC" and "traditional Chinese medicine", "TCM", or "natural plant", "herb", etc., with the aim of elucidating the intrinsic mechanisms of traditional Chinese medicine and natural medicine in the treatment of HR + BC.

RESULTS

TCM/natural medicine monomers and formulas can regulate the expression of related genes and proteins through the PI3K/AKT, JAK2/STAT3, MAPK, Wnt and other signalling pathways, inhibit the proliferation and metastasis of HR + BC tumours, play a synergistic role in combination with endocrine drugs, and reverse endocrine drug resistance.

CONCLUSION

The wide variety of TCM/natural medicine components makes the research and development of new methods of TCM for BC treatments more selective and innovative. Although progress has been made on research on TCM/natural medicine, there are still many problems in clinical and basic experimental designs, and more in-depth scientific explorations and research are still needed.

A comprehensive review on Ellagic acid in breast cancer treatment: From cellular effects to molecular mechanisms of action

Globally, breast cancer (BC) is the leading cause of cancer-related deaths in women. Hence, developing a therapeutic plan to overcome the disease is crucial. Numerous factors such as endogenous hormones and environmental factors may play a role in the pathophysiology of BC. Regarding the multi-modality treatment of BC, natural compounds like ellagic acid (EA) received has received increased interest in antitumor efficacy with lower adverse effects. Based on the results of this comprehensive review, EA has multiple effects on BC cells including (1) suppresses the growth of BC cells by arresting the cell cycle in the G0/G1 phase, (2) suppresses migration, invasion, and metastatic, (3) stimulates apoptosis in MCF-7 cells via TGF-β/Smad3 signaling axis, (4) inhibits CDK6 that is important in cell cycle regulation, (5) binds to ACTN4 and induces its degradation via the ubiquitin-proteasome pathway, inducing decreased cell motility and invasion in BC cells, (6) inhibits the PI3K/AKT pathway, and (7) inhibits angiogenesis-associated activities including proliferation (reduces VEGFR-2 tyrosine kinase activity). In conclusion, EA exhibits anticancer activity through various molecular mechanisms that influence key cellular processes like apoptosis, cell cycle, angiogenesis, and metastasis in BC. However, further researches are essential to fully elucidate its molecular targets and implications for clinical applications.

Molecular Action of Tamoxifen in the Ovaries of Rats with Mammary Neoplasia

Tamoxifen (TAM) is a drug commonly used in patients with breast cancer. The anticancer effect of TAM occurs via its ability to antagonize estrogen-dependent growth of mammary epithelial cells. Previously, we demonstrated that TAM prevented the chemotherapy-induced loss of ovarian follicular reserves in both cancer-free rats and rats with cancer. Such follicular loss is a main cause of infertility in young women treated for cancer. The current study was undertaken to discover the molecules and intracellular pathways involved in the action of TAM in the ovaries of rats with mammary tumors. To meet this goal we used transcriptomic (RNA-Seq) and proteomic (2D-DIGE/MS) approaches. TAM inhibited the expression of genes and lncRNAs involved in ovarian steroidogenesis. Moreover, TAM altered the expression of genes related to primordial follicle activation or arrest. In addition, proteomic screening indicated the importance of basic metabolic processes in the ovarian actions of TAM. Although simple extrapolation of these data to humans is not possible, the results of this study emphasize the need to explore the ability of TAM to affect ovarian function in women undergoing cancer treatment.

Combination of tamoxifen and D-limonene enhances therapeutic efficacy in breast cancer cells

Breast cancer one of the most common diseases in women, has a high death and morbidity rate. Tamoxifen being very much effective in the chemoprevention of breast cancer has been shown to develop resistance during the course of treatment making it difficult for patient's survival. By combining tamoxifen with naturally occurring substances having similar activities, might control the toxicity and increase the susceptibility towards the treatment. As a natural compound, D-limonene has been reported to inhibit the growth of certain malignancies significantly. The main goal of our work is to investigate the combinatorial antitumor effects of D-limonene and tamoxifen in MCF-7 cells, as well as understand the potential underlying anticancer mechanism. MTT assays, colony formation assays, DAPI and Annexin V-FITC labeling, flow cytometer analysis, and western blot analysis were used to explore the details of anticancer mechanism. The combined effects of tamoxifen with D-limonene have shown significant decrease in the cell viability of MCF 7 cells. According to flow cytometer analyses and Annexin V/PI staining, D-limonene has been found to increase tamoxifen-mediated apoptosis as compared to the treatment alone in these cells. Additionally, cell growth has been found to be arrested at G1 phase by regulating cyclin D1 and cyclin B1. Our research consequently provided the first evidence that combining D-limonene and tamoxifen might increase the anticancer efficacy by inducing apoptosis in MCF 7 breast cancer cells. This combinatorial treatment strategy demands more research which might fulfill the need for improved treatment efficacy in controlling breast cancer.

An Update on Tamoxifen and the Chemo-Preventive Potential of Vitamin E in Breast Cancer Management

Breast cancer (BC) is the most common female cancer in terms of incidence and mortality worldwide. Tamoxifen (Nolvadex) is a widely prescribed, oral anti-estrogen drug for the hormonal treatment of estrogen-receptor-positive BC, which represents 70% of all BC subtypes. This review assesses the current knowledge on the molecular pharmacology of tamoxifen in terms of its anticancer and chemo-preventive actions. Due to the importance of vitamin E compounds, which are widely taken as a supplementary dietary component, the review focuses only on the potential importance of vitamin E in BC chemo-prevention. The chemo-preventive and onco-protective effects of tamoxifen combined with the potential effects of vitamin E can alter the anticancer actions of tamoxifen. Therefore, methods involving an individually designed, nutritional intervention for patients with BC warrant further consideration. These data are of great importance for tamoxifen chemo-prevention strategies in future epidemiological studies.

Synthesis and anti-proliferative activity of dehydroabietinol derivatives bearing a triazole moiety

In search of more efficacious antitumor agents, a series of novel dehydroabietinol derivatives containing a triazole moiety was synthesized, and evaluated for cytotoxicity against four human cancer cell lines. Many exhibited superior cytotoxic profiles compared to the parent molecule, dehydroabietic acid. In particular, compounds 5g, 5i and 5j exhibited promising cytotoxicity with IC50 values ranging from 4.84 to 9.62 μM against all the test cell lines. Cell clone formation and migration tests of compound 5g showed that it not only effectively inhibited the formation of MGC-803 cell colonies but also inhibited the MGC-803 cell migration and invasion. Additionally, the preliminary pharmacological mechanism indicated compound 5g induced apoptosis, arrested the mitotic process at the G0/G1 phase of the cell cycle, reduced the mitochondrial membrane potential, and increased the intracellular ROS and Ca2+ levels.

Recent advances of bioactive proteins/polypeptides in the treatment of breast cancer

Proteins do not only serve as nutrients to fulfill the demand for food, but also are used as a source of bioactive proteins/polypeptides for regulating physical functions and promoting physical health. Female breast cancer has the highest incidence in the world and is a serious threat to women's health. Bioactive proteins/polypeptides exert strong anti-tumor effects and exhibit inhibition of multiple breast cancer cells. This review discussed the suppressing effects of bioactive proteins/polypeptides on breast cancer in vitro and in vivo, and their mechanisms of migration and invasion inhibition, apoptosis induction, and cell cycle arrest. This may contribute to providing a basis for the development of bioactive proteins/polypeptides for the treatment of breast cancer.

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Tackling heterogeneity in treatment-resistant breast cancer using a broad-spectrum therapeutic approach

Tumor heterogeneity can contribute to the development of therapeutic resistance in cancer, including advanced breast cancers. The object of the Halifax project was to identify new treatments that would address mechanisms of therapeutic resistance through tumor heterogeneity by uncovering combinations of therapeutics that could target the hallmarks of cancer rather than focusing on individual gene products. A taskforce of 180 cancer researchers, used molecular profiling to highlight key targets responsible for each of the hallmarks of cancer and then find existing therapeutic agents that could be used to reach those targets with limited toxicity. In many cases, natural health products and re-purposed pharmaceuticals were identified as potential agents. Hence, by combining the molecular profiling of tumors with therapeutics that target the hallmark features of cancer, the heterogeneity of advanced-stage breast cancers can be addressed.