Tamoxifen resistance in breast cancer

Functional combination of resveratrol and tamoxifen to overcome tamoxifen-resistance in breast cancer cells

Researchers are encountering challenges in addressing the issue of cancer cells becoming unresponsive to various chemotherapy treatments due to drug resistance. This study was designed to study the influence of antioxidant resveratrol (RSV) to sensitize resistant breast cancer (BC) cells toward tamoxifen (TAM). The cytotoxic effects of RSV and TAM against TAM-resistant LCC2 cells and their parental michigan cancer foundation-7 BC cells were determined by sulphorhodamine B assay. Further, the expression levels of multidrug resistance (MDR) genes including ABCB1, ABCC2, ABCG2, and MRP1 using quantitative polymerase chain reaction, apoptosis induction, and reactive oxygen species (ROS) content using flow cytometry were evaluated in either LCC2 cells treated with RSV, TAM, or their combination. The obtained results showed that resistant cells have a magnificent level of MDR genes. This elevated expression dramatically lowered upon receiving the combined therapy of RSV and TAM. Additionally, our work assessed the possible role of RSV in modulating the expression of MDR genes by controlling the expression of certain microRNAs (miRNAs) that target ATP-binding cassette (ABC) transporters. According to the obtained data, the TAM and RSV combination increased the expression of tumor inhibitor miRNAs such miR-10b-3p, miR-195-3p, and miR-223-3p, which made LCC2 cells more sensitive to TAM. Furthermore, this combination showed an elevation in apoptotic levels and total ROS content. The combination between RSV and TAM could be a functional therapy in the fight against TAM-resistant BC cells via modulating miRNA and ABC transporters.

Crosstalk of methylation and tamoxifen in breast cancer (Review)

Tamoxifen is a widely used anti‑estrogen drug in the endocrine therapy of breast cancer (BC). It blocks estrogen signaling by competitively binding to estrogen receptor α (ERα), thereby inhibiting the growth of BC cells. However, with the long‑term application of tamoxifen, a subset of patients with BC have shown resistance to tamoxifen, which leads to low overall survival and progression‑free survival. The molecular mechanism of resistance is mainly due to downregulation of ERα expression and abnormal activation of the PI3K/AKT/mTOR signaling pathway. Moreover, the downregulation of targeted gene expression mediated by DNA methylation is an important regulatory mode to control protein expression. In the present review, methylation and tamoxifen are briefly introduced, followed by a focus on the effect of methylation on tamoxifen resistance and sensitivity. Finally, the clinical application of methylation for tamoxifen is described, including its use as a prognostic indicator. Finally, it is hypothesized that when methylation is used in combination with tamoxifen, it could recover the resistance of tamoxifen.

The anti-aromatase and anti-estrogenic activity of plant products in the treatment of estrogen receptor-positive breast cancer

Despite being the focal point of decades of research, female breast cancer (BC) continues to be one of the most lethal cancers in the world. Given that 80 % of all diagnosed BC cases are estrogen receptor-positive (ER+) with carcinogenesis driven by estrogen-ERα signalling, current standard of care (SOC) hormone therapies are geared towards modulating the function and expression levels of estrogen and its receptors, ERα and ERβ. Currently, aromatase inhibitors (AIs), selective ER modulators (SERMs) and selective ER degraders (SERDs) are clinically prescribed for the management and treatment of ER+ BC, with the anti-aromatase activity of AIs abrogating estrogen biosynthesis, while the anti-estrogenic SERMs and SERDs antagonise and degrade the ER, respectively. The use of SOC hormone therapies is, however, significantly hampered by the onset of severe side-effects and the development of resistance. Given that numerous studies have reported on the beneficial effects of plant compounds and/or extracts and the multiple pathways through which they target ER+ breast carcinogenesis, recent research has focused on the use of dietary chemopreventive agents for BC management. When combined with SOC treatments, several of these plant components and/or extracts have demonstrated improved efficacy and/or synergistic impact. Moreover, despite a lack of in vivo investigations, plant products are generally reported to have a lower side-effect profile than SOC therapies and are therefore thought to be a safer therapeutic choice. Thus, the current review summarizes the findings from the last five years regarding the anti-aromatase and anti-estrogenic activity of plant products, as well as their synergistic anti-ER+ BC effects in combination with SOC therapies.

Auraptene Boosts the Efficacy of the Tamoxifen Metabolites Endoxifen and 4-OH-Tamoxifen in a Chemoresistant ER+ Breast Cancer Model

Approximately 80% of breast cancer (BC) cases are estrogen receptor positive (ER+) and sensitive to hormone treatment; Tamoxifen is a prodrug, and its main plasmatic active metabolites are 4-hydroxytamoxifen (4-OH Tam) and endoxifen. Despite the effectiveness of tamoxifen therapy, resistance can be developed. An increment in eukaryotic initiation factor-4A complex (eIF4A) activity can result in tamoxifen-resistant tumor cells. For this work, we developed a cell variant resistant to 4-OH Tam and endoxifen, denominated MCF-7Var E; then, the aim of this research was to reverse the acquired resistance of this variant to tamoxifen metabolites by incorporating the natural compound auraptene. Combination treatments of tamoxifen derivatives and auraptene successfully sensitized the chemoresistant MCF-7Var E. Our data suggest a dual regulation of eIF4A and ER by auraptene. Joint treatments of 4-OH Tam and endoxifen with auraptene identified a novel focus for chemoresistance disruption. Synergy was observed using the auraptene molecule and tamoxifen-derived metabolites, which induced a sensitization in MCF-7Var E cells and ERα parental cells that was not observed in triple-negative breast cancer cells (TNBC). Our results suggest a synergistic effect between auraptene and tamoxifen metabolites in a resistant ER+ breast cancer model, which could represent the first step to achieving a pharmacologic strategy.

The vitamin D analog EB1089 sensitizes triple-negative breast cancer cells to the antiproliferative effects of antiestrogens

PURPOSE

Patients bearing estrogen receptor (ER)α-negative breast cancer tumors confront poor prognosis and are typically unresponsive to hormone therapy. Previous studies have shown that calcitriol, the active vitamin D metabolite, can induce ERα expression in ERα-negative cells. EB1089, a calcitriol analog with reduced calcemic effects, exhibits greater potency than calcitriol in inhibiting cancer cell growth. However, the impact of EB1089 on ERα expression in triple-negative breast cancer (TNBC) cells remains unexplored. This study aims to investigate whether EB1089 could induce functional ERα expression in TNBC cell lines, potentially enabling the antiproliferative effects of antiestrogens.

MATERIALS AND METHODS

TNBC cell lines HCC1806 and HCC1937 were treated with EB1089, and ERα expression was analyzed using real-time PCR and Western blots. The transcriptional activity of induced ERα was evaluated through a luciferase reporter assay. The antiproliferative effects of tamoxifen and fulvestrant antiestrogens were assessed using the sulforhodamine B assay in the EB1089-treated cells.

RESULTS

Our findings indicated that EB1089 significantly induced ERα mRNA and protein expression in TNBC cells. Moreover, EB1089-induced ERα exhibited transcriptional activity and effectively restored the inhibitory effects of antiestrogens, thereby suppressing cell proliferation in TNBC cells.

CONCLUSION

EB1089 induced the expression of functional ERα in TNBC cells, restoring the antiproliferative effects of antiestrogens. These results highlight the potential of using EB1089 as a promising strategy for re-establishment of the antiproliferative effect of antiestrogens as a possible management for TNBC. This research lays the foundation for potential advancements in TNBC treatment, offering new avenues for targeted and effective interventions.

Drug resistance in human cancers - Mechanisms and implications

Cancers have complex etiology and pose a significant impact from the health care perspective apart from the socio-economic implications. The enormity of challenge posed by cancers can be understood from the fact that clinical trials for cancer therapy has yielded minimum potential promises compared to those obtained for other diseases. Surgery, chemotherapy and radiotherapy continue to be the mainstay therapeutic options for cancers. Among the challenges posed by these options, induced resistance to chemotherapeutic drugs is probably the most significant contributor for poor prognosis and ineffectiveness of the therapy. Drug resistance is a property exhibited by almost all cancer types including carcinomas, leukemias, myelomas, sarcomas and lymphomas. The mechanisms by which drug resistance is induced include the factors within the tumor microenvironment, mutations in the genes responsible for drug metabolism, changes in the surface drug receptors and increased drug efflux. We present here comprehensively the drug resistance in cancers along with their mechanisms. Also, apart from resistance to regularly used chemotherapeutic drugs, we present resistance induction to new generation therapeutic agents such as monoclonal antibodies. Finally, we have discussed the experimental approaches to understand the mechanisms underlying induction of drug resistance and potential ways to mitigate induced drug resistance.

CircRNAs as upstream regulators of miRNA//HMGA2 axis in human cancer

High mobility group protein A2 (HMGA2) is widely recognized as a chromatin-binding protein, whose overexpression is observed in nearly all human cancers. It exerts its oncogenic effects by influencing various cellular processes such as the epithelial-mesenchymal transition, cell differentiation, and DNA damage repair. MicroRNA (miRNA) serves as a pivotal gene expression regulator, concurrently modulating multiple genes implicated in cancer progression, including HMGA2. It also serves as a significant biomarker for cancer. Circular RNA (circRNA) plays a crucial role in gene regulation primarily by sequestering miRNAs and impeding their ability to enhance the expression of other genes, including HMGA2. Increasingly, studies have underscored the vital role of miRNA/HMGA2 interactions in cancer. Given the significance of circRNA as an upstream regulatory mediator and the complexity of regulatory mechanisms, we hereby present a comprehensive overview of the pivotal role of circRNAs as upstream regulators of the miRNA//HMGA2 axis in human cancers. This insight may herald a novel direction for future cancer research.

USP36 promotes tumorigenesis and tamoxifen resistance in breast cancer by deubiquitinating and stabilizing ERα

BACKGROUND

Breast cancer is the most prevalent cancer in women globally. Over-activated estrogen receptor (ER) α signaling is considered the main factor in luminal breast cancers, which can be effectively managed with selective estrogen receptor modulators (SERMs) like tamoxifen. However, approximately 30-40% of ER + breast cancer cases are recurrent after tamoxifen therapy. This implies that the treatment of breast cancer is still hindered by resistance to tamoxifen. Recent studies have suggested that post-translational modifications of ERα play a significant role in endocrine resistance. The stability of both ERα protein and its transcriptome is regulated by a balance between E3 ubiquitin ligases and deubiquitinases. According to the current knowledge, approximately 100 deubiquitinases are encoded in the human genome, but it remains unclear which deubiquitinases play a critical role in estrogen signaling and endocrine resistance. Thus, decoding the key deubiquitinases that significantly impact estrogen signaling, including the control of ERα expression and stability, is critical for the improvement of breast cancer therapeutics.

METHODS

We used several ER positive breast cancer cell lines, DUB siRNA library screening, xenograft models, endocrine-resistant (ERα-Y537S) model and performed immunoblotting, real time PCR, RNA sequencing, immunofluorescence, and luciferase activity assay to investigate the function of USP36 in breast cancer progression and tamoxifen resistance.

RESULTS

In this study, we identify Ubiquitin-specific peptidase 36 (USP36) as a key deubiquitinase involved in ERα signaling and the advancement of breast cancer by deubiquitinases siRNA library screening. In vitro and in vivo studies showed that USP36, but not its catalytically inactive mutant (C131A), could promote breast cancer progression through ERα signaling. Conversely, silencing USP36 inhibited tumorigenesis. In models resistant to endocrine therapy, silencing USP36 destabilized the resistant form of ERα (Y537S) and restored sensitivity to tamoxifen. Molecular studies indicated that USP36 inhibited K48-linked polyubiquitination of ERα and enhanced the ERα transcriptome. It is interesting to note that our results suggest USP36 as a novel biomarker for treatment of breast cancer.

CONCLUSION

Our study revealed the possibility that inhibiting USP36 combined with tamoxifen could provide a potential therapy for breast cancer.

Increased prevalence of hybrid epithelial/mesenchymal state and enhanced phenotypic heterogeneity in basal breast cancer

Intra-tumoral phenotypic heterogeneity promotes tumor relapse and therapeutic resistance and remains an unsolved clinical challenge. Decoding the interconnections among different biological axes of plasticity is crucial to understand the molecular origins of phenotypic heterogeneity. Here, we use multi-modal transcriptomic data-bulk, single-cell, and spatial transcriptomics-from breast cancer cell lines and primary tumor samples, to identify associations between epithelial-mesenchymal transition (EMT) and luminal-basal plasticity-two key processes that enable heterogeneity. We show that luminal breast cancer strongly associates with an epithelial cell state, but basal breast cancer is associated with hybrid epithelial/mesenchymal phenotype(s) and higher phenotypic heterogeneity. Mathematical modeling of core underlying gene regulatory networks representative of the crosstalk between the luminal-basal and epithelial-mesenchymal axes elucidate mechanistic underpinnings of the observed associations from transcriptomic data. Our systems-based approach integrating multi-modal data analysis with mechanism-based modeling offers a predictive framework to characterize intra-tumor heterogeneity and identify interventions to restrict it.

Drug reactive metabolite-induced hepatotoxicity: a comprehensive review

Nowadays, drug-induced liver toxicity (DILT) is one of the main contributing factors to severe liver disease. In the United States (US) alone, DILT is the cause of more than 50% of instances of acute liver failure. Prescription or over-the-counter drugs, xenobiotics, and herbal and nutritional supplements can cause DILT and could produce anomalies in hepatic function tests. Some drugs induce hepatotoxicity directly, and others induce it indirectly (i. e. through their toxic or reactive metabolites). Currently, the United States Food and Drug Administration (US FDA) has issued black box warnings for about 1279 drugs due to their hepatotoxicity. When we analyzed their mechanism in inducing hepatotoxicity, we found nearly 18 drugs causing hepatotoxicity by their toxic metabolites. In this review, we attempted to highlight the well-known drugs that induce hepatotoxicity indirectly through their toxic metabolites including the enzymes involved in the formation of these metabolites. The Cytochrome P-450 (CYP), Hypoxanthine phosphoribosyltransferase 1, Alcohol oxidase, Uridine diphosphate (UDP)-glucuronosyltransferases, Xanthine dehydrogenase, Purine-nucleoside phosphorylase, Xanthine oxidase, Thiopurine S-methyltransferase, Inosine-5'-monophosphate dehydrogenase, and aldehyde dehydrogenase are involving in the formation of toxic metabolites. The metabolic reactions and enzymes discussed in this review help toxicologists, pharmacologists, and chemists to design and develop hepatotoxicity-free pharmaceutical products containing the inhibitors of these enzymes to reduce hepatotoxicity and improve human health.

Naringenin as potent anticancer phytocompound in breast carcinoma: from mechanistic approach to nanoformulations based therapeutics

The bioactive compounds present in citrus fruits are gaining broader acceptance in oncology. Numerous studies have deciphered naringenin's antioxidant and anticancer potential in human and animal studies. Naringenin (NGE) potentially suppresses cancer progression, thereby improving the health of cancer patients. The pleiotropic anticancer properties of naringenin include inhibition of the synthesis of growth factors and cytokines, inhibition of the cell cycle, and modification of several cellular signaling pathways. As an herbal remedy, naringenin has significant pharmacological properties, such as anti-inflammatory, antioxidant, neuroprotective, hepatoprotective, and anti-cancer activities. The inactivation of carcinogens following treatment with pure naringenin, naringenin-loaded nanoparticles, and naringenin combined with anti-cancer agents was demonstrated by data in vitro and in vivo studies. These studies included colon cancer, lung neoplasms, breast cancer, leukemia and lymphoma, pancreatic cancer, prostate tumors, oral squamous cell carcinoma, liver cancer, brain tumors, skin cancer, cervical and ovarian cancers, bladder neoplasms, gastric cancer, and osteosarcoma. The effects of naringenin on processes related to inflammation, apoptosis, proliferation, angiogenesis, metastasis, and invasion in breast cancer are covered in this narrative review, along with its potential to develop novel and secure anticancer medications.

Navigating the Intricacies of Tumor Heterogeneity: An Insight into Potential Prognostic Breast Cancer Biomarkers

Breast cancer is a heterogeneous disease with diverse histological and molecular subtypes. Luminal breast tumors are the most diagnosed subtype. In luminal breast cancer, hormone receptors (including ER, PR, HER2) play a diagnostic and prognostic role. Despite the effectiveness of endocrine therapy in luminal breast tumors, tumor recurrence and resistance occur, and this may highlight evolutionary strategies for survival driven by stemness. In this review we thus consider the association between estrogen signaling and stemness in mediating tumor processes. Many studies report stemness as one of the factors promoting tumor progression. Its association with estrogen signaling warrants further investigation and provides an opportunity for the identification of novel biomarkers which may be used for diagnostic, prognostic, and therapeutic purposes. Breast cancer stem cells have been characterized (CD44+ CD24-) and their role in promoting treatment resistance and tumor recurrence widely studied; however, the complexity of tumor progression which also involve microenvironmental factors suggests the existence of more varied cell phenotypes which mediate stemness and its role in tumor progression.

Comprehensive analysis of prohibited substances and methods in sports: Unveiling trends, pharmacokinetics, and WADA evolution

This review systematically compiles sports-related drugs, substances, and methodologies based on the most frequently detected findings from prohibited lists published annually by the World Anti-Doping Agency (WADA) between 2003 and 2021. Aligned with structure of the 2023 prohibited list, it covers all proscribed items and details the pharmacokinetics and pharmacodynamics of five representatives from each section. Notably, it explores significant metabolites and metabolic pathways associated with these substances. Adverse analytical findings are summarized in tables for clarity, and the prevalence is visually represented through charts. The review includes a concise historical overview of doping and WADA's role, examining modifications in the prohibited list for an understanding of evolving anti-doping measures.

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.

Protein arginine methyltransferases (PRMTs): Orchestrators of cancer pathogenesis, immunotherapy dynamics, and drug resistance

Protein Arginine Methyltransferases (PRMTs) are a family of enzymes regulating protein arginine methylation, which is a post-translational modification crucial for various cellular processes. Recent studies have highlighted the mechanistic role of PRMTs in cancer pathogenesis, immunotherapy, and drug resistance. PRMTs are involved in diverse oncogenic processes, including cell proliferation, apoptosis, and metastasis. They exert their effects by methylation of histones, transcription factors, and other regulatory proteins, resulting in altered gene expression patterns. PRMT-mediated histone methylation can lead to aberrant chromatin remodeling and epigenetic changes that drive oncogenesis. Additionally, PRMTs can directly interact with key signaling pathways involved in cancer progression, such as the PI3K/Akt and MAPK pathways, thereby modulating cell survival and proliferation. In the context of cancer immunotherapy, PRMTs have emerged as critical regulators of immune responses. They modulate immune checkpoint molecules, including programmed cell death protein 1 (PD-1), through arginine methylation. Drug resistance is a significant challenge in cancer treatment, and PRMTs have been implicated in this phenomenon. PRMTs can contribute to drug resistance through multiple mechanisms, including the epigenetic regulation of drug efflux pumps, altered DNA damage repair, and modulation of cell survival pathways. In conclusion, PRMTs play critical roles in cancer pathogenesis, immunotherapy, and drug resistance. In this overview, we have endeavored to illuminate the mechanistic intricacies of PRMT-mediated processes. Shedding light on these aspects will offer valuable insights into the fundamental biology of cancer and establish PRMTs as promising therapeutic targets.

miR-770-5p-induced cellular switch to sensitize trastuzumab resistant breast cancer cells targeting HER2/EGFR/IGF1R bidirectional crosstalk

Background/aim

Studies highlighted the bidirectional crosstalk between the HER family members in breast cancer as resistance mechanism to anti-HER agents. Cross-signaling between HER2/EGFR and ER/IGF1R could play role in the development of resistance to therapeutics hence stimulating cell growth. To overcome this resistance, combined therapies targeting both pathways simultaneously have been proposed as an effective strategy. The involvement of miRNAs in resistance of targeted therapies like trastuzumab was demonstrated in recent studies. Hence the regulation of miRNAs in resistance state could reverse the cell behaviour to drugs. Previously we found that overexpression of miR-770-5p downregulated AKT and ERK expression through HER2 signaling and potentiated the effect of trastuzumab. In this study we examined the impact of miR-770-5p on trastuzumab resistance.

Materials and methods

Cells were treated with tamoxifen or trastuzumab to examine their role in bidirectional crosstalk. The molecule mechanism of miR-770-5p on HER2/EGFR/IGF1R bidirectional crosstalk was explored by western blot. The expression of miR-770-5p in trastuzumab resistant cells was examined by q-PCR. To investigate the effect of miR-770-5p on cancer cell proliferation in trastuzumab resistance state, resistant cells were analyzed by iCELLigence real-time cell analyzer.

Results

miR-770-5p expression was significantly downregulated in trastuzumab-resistant BT-474 and SK-BR-3 cells. Overexpression of miR-770-5p sensitized the resistant cells to trastuzumab, as evidenced by reduced cell proliferation and increased cell viability. Additionally, in resistant cells, increased expression and activation of EGFR and IGF1R were observed. However, miR-770-5p overexpression resulted in decreased phosphorylation of AKT and ERK, indicating its suppressive role in EGFR/HER2 signaling. Furthermore, miR-770-5p downregulated the expression of IGF1R and mTOR, suggesting its involvement in regulating the escape signaling mediated by IGF1R in resistance.

Conclusion

In conclusion, our findings demonstrate the critical role of miR-770-5p in regulating bidirectional crosstalk and overcoming trastuzumab resistance in breast cancer cells. These results highlight the potential of miR-770-5p as a therapeutic target to improve the efficacy of targeted therapies and address resistance mechanisms in breast cancer.

The effect of human umbilical cord mesenchymal stem cells conditioned medium combined with tamoxifen drug on BRCA1 and BRCA2 expression in breast cancer mouse models

BACKGROUND

A growing number of studies has indicated that the expression of Breast Cancer Susceptibility Genes 1 (BRCA1) and BRCA2 contribute to the resistance to DNA-damaging chemotherapies. Tamoxifen induces tumor cell death by suppressing estrogen receptor (ER) signaling and inducing DNA damage, and BRCA1 upregulation causes Tamoxifen chemoresistance in breast cancer cells. Consequently, this research study aimed to investigate the possible therapeutic effect of Human Umbilical Cord Mesenchymal Stem Cells Conditioned Medium (UCMSCs-CM) on sensitizing breast cancer cells to Tamoxifen by regulating BRCA1 and BRCA2 expression in vivo.

METHODS

Forty female mice, 4-8 weeks old, with weight of 150 g, were used for this study. Mouse 4T1 breast tumor models were established and then treated with UCMSCs-CM and Tamoxifen alone or in combination. After 10 days, the tumor masses were collected and the expression levels of BRCA1 and BRCA2 were evaluated using qRT-PCR assay.

RESULTS

The results obtained from qRT-PCR assay illustrated that UCMSCs-CM, either alone or in combination with Tamoxifen, significantly downregulated the mRNA expression levels of BRCA1 in breast cancer mouse models. However, both UCMSCs-CM and Tamoxifen indicated no statistically significant impact on BRCA2 mRNA expression compared to controls.

CONCLUSION

Our findings evidenced that UCMSCs-CM could be considered as a potential therapeutic option to modulate Tamoxifen chemosensitivity by regulating BRCA1 in breast cancer.

Pretreatment Circulating Albumin, Platelet, and RDW-SD Associated with Worse Disease-Free Survival in Patients with Breast Cancer

Objective

Breast cancer is the second most common malignancy globally and a leading cause of cancer death in women. Analysis of factors related to disease-free survival (DFS) has improved understanding of the disease and characteristics related to recurrence. The aim of this study was to investigate the predictors of DFS in patients with breast cancer to enable the identification of patients at high risk who may benefit from prevention interventions.

Methods

We retrospectively analyzed 559 women with breast cancer who underwent treatment between 2004 and 2022. The study endpoint was DFS. Recurrence was defined as local recurrence, regional recurrence, distant metastases, contralateral breast cancer, other second primary cancer, and death. Baseline tumor-related characteristics, treatment-related characteristics, sociodemographic and biochemical data were analyzed using Cox proportional hazards analysis.

Results

The median DFS was 45 months (range, 2 to 225 months). Breast cancer recurred in 86 patients (15.4%), of whom 10 had local recurrence, 10 had regional recurrence, 17 had contralateral breast cancer, 29 had distant metastases, 10 had second primary cancer, and 10 patients died. Multivariate forward stepwise Cox regression analysis showed that AJCC stage III, Ki67 ≥14%, albumin, platelet, and red cell distribution width-standard deviation (RDW-SD) were predictors of worse DFS. In addition, the effects of albumin, platelet, and RDW-SD on disease recurrence were confirmed by structural equation model (SEM) analysis.

Conclusion

In addition to the traditional predictors of worse DFS such as AJCC stage III and Ki67 ≥14%, lower pretreatment circulating albumin, higher pretreatment circulating platelet count and RDW-SD could significantly predict worse DFS in this study, and SEM delineated possible causal pathways and inter-relationships of albumin, platelet, and RDW-SD contributing to the disease recurrence among Chinese women with breast cancer.

Oxysterols as Biomarkers of Aging and Disease

Oxysterols derive from either enzymatic or non-enzymatic oxidation of cholesterol. Even though they are produced as intermediates of bile acid synthesis pathway, they are recognised as bioactive compounds in cellular processes. Therefore, their absence or accumulation have been shown to be associated with disease phenotypes. This chapter discusses the contribution of oxysterol to ageing, age-related diseases such as neurodegeneration and various disorders such as cancer, cardiovascular disease, diabetes, metabolic and ocular disorders. It is clear that oxysterols play a significant role in development and progression of these diseases. As a result, oxysterols are being investigated as suitable markers for disease diagnosis purposes and some drug targets are in development targeting oxysterol pathways. However, further research will be needed to confirm the suitability of these potentials.

Novel Strategies Using Sagacious Targeting for Site-Specific Drug Delivery in Breast Cancer Treatment: Clinical Potential and Applications

For more than a decade, researchers have been working to achieve new strategies and smart targeting drug delivery techniques and technologies to treat breast cancer (BC). Nanotechnology presents a hopeful strategy for targeted drug delivery into the building of new therapeutics using the properties of nanomaterials. Nanoparticles are of high regard in the field of diagnosis and the treatment of cancer. The use of these nanoparticles as an encouraging approach in the treatment of various cancers has drawn the interest of researchers in recent years. In order to achieve the maximum therapeutic effectiveness in the treatment of BC, combination therapy has also been adopted, leading to minimal side effects and thus an enhancement in the quality of life for patients. This review article compares, discusses and criticizes the approaches to treat BC using novel design strategies and smart targeting of site-specific drug delivery systems.

Hot-Spot Residue-Based Virtual Screening of Novel Selective Estrogen-Receptor Degraders for Breast Cancer Treatment

The estrogen-receptor alfa (ERα) is considered pivotal for breast cancer treatment. Although selective estrogen-receptor degraders (SERDs) have been developed to induce ERα degradation and antagonism, their agonistic effect on the uterine tissue and poor pharmacokinetic properties limit further application of ERα; thus, discovering novel SERDs is necessary. The ligand preferentially interacts with several key residues of the protein (defined as hot-spot residues). Improving the interaction with hot-spot residues of ERα offers a promising avenue for obtaining novel SERDs. In this study, pharmacophore modeling, molecular mechanics/generalized Born surface area (MM/GBSA), and amino-acid mutation were combined to determine several hot-spot residues. Focusing on the interaction with these hot-spot residues, hit fragments A1-A3 and A9 were virtually screened from two fragment libraries. Finally, these hit fragments were linked to generate compounds B1-B3, and their biological activities were evaluated. Remarkably, compound B1 exhibited potent antitumor activity against MCF-7 cells (IC50 = 4.21 nM), favorable ERα binding affinity (Ki = 14.6 nM), and excellent ERα degradative ability (DC50 = 9.7 nM), which indicated its potential to evolve as a promising SERD for breast cancer treatment.

Role of monocarboxylate transporter I/lactate dehydrogenase B-mediated lactate recycling in tamoxifen-resistant breast cancer cells

Although tamoxifen (TAM) is widely used in patients with estrogen receptor-positive breast cancer, the development of tamoxifen resistance is common. The previous finding suggests that the development of tamoxifen resistance is driven by epiregulin or hypoxia-inducible factor-1α-dependent glycolysis activation. Nonetheless, the mechanisms responsible for cancer cell survival and growth in a lactic acid-rich environment remain elusive. We found that the growth and survival of tamoxifen-resistant MCF-7 cells (TAMR-MCF-7) depend on glycolysis rather than oxidative phosphorylation. The levels of the glycolytic enzymes were higher in TAMR-MCF-7 cells than in parental MCF-7 cells, whereas the mitochondrial number and complex I level were decreased. Importantly, TAMR-MCF-7 cells were more resistant to low glucose and high lactate growth conditions. Isotope tracing analysis using 13C-lactate confirmed that lactate conversion to pyruvate was enhanced in TAMR-MCF-7 cells. We identified monocarboxylate transporter1 (MCT1) and lactate dehydrogenase B (LDHB) as important mediators of lactate influx and its conversion to pyruvate, respectively. Consistently, AR-C155858 (MCT1 inhibitor) inhibited the proliferation, migration, spheroid formation, and in vivo tumor growth of TAMR-MCF-7 cells. Our findings suggest that TAMR-MCF-7 cells depend on glycolysis and glutaminolysis for energy and support that targeting MCT1- and LDHB-dependent lactate recycling may be a promising strategy to treat patients with TAM-resistant breast cancer.

Anti-MUC1 nanobody can synergize the Tamoxifen and Herceptin effects on breast cancer cells by inducing ER, PR and HER2 overexpression

INTRODUCTION

One of the most pressing concerns associated with breast cancer-targeted therapies is resistance to Tamoxifen and Herceptin. Such drug resistance is usually characterized by reduced expression of certain cell surface receptors. Some biological regimens can induce perceptible overexpression of these receptors in favor of drug responsiveness.

MATERIAL AND METHODS

In this research, drug-responsive MCF-7 and SKBR-3, along with drug-resistant MCF-7R (Tamoxifen resistant) and JIMT-1 (Herceptin resistant) breast cancer cell lines in 2D and 3D cultures were exposed to anti-MUC1 nanobody and then assessed for their ER, PR, and HER2 gene and protein expression using qRT-PCR and immunofluorescent staining analyses. Cell viability and the synergistic relationships of combination treatments were determined with MTT assay followed by CompuSyn software. Apoptotic cells were evaluated with Annexin V/propidium Iodide (PI) and acridine orange/ethidium bromide (AO/EB) staining.

RESULTS

Anti-MUC1 exposure elevated the expression levels of ER (42 folds), PR (18.5 folds), and HER2 (4.7 folds). As a result of co-treatment, the IC50 levels for Tamoxifen and Herceptin were reduced by up to 10 and 3 folds, respectively. MCF-7R cells responded positively to Tamoxifen, as evidenced by a 5-fold reduction in the IC50 and enhanced apoptosis.

CONCLUSION

The ER, PR, and HER2 overexpression after MUC1 blocking could signal drug hypersensitization and facilitate drug resistance management.

Multi-modal transcriptomic analysis unravels enrichment of hybrid epithelial/mesenchymal state and enhanced phenotypic heterogeneity in basal breast cancer

Intra-tumoral phenotypic heterogeneity promotes tumor relapse and therapeutic resistance and remains an unsolved clinical challenge. It manifests along multiple phenotypic axes and decoding the interconnections among these different axes is crucial to understand its molecular origins and to develop novel therapeutic strategies to control it. Here, we use multi-modal transcriptomic data analysis - bulk, single-cell and spatial transcriptomics - from breast cancer cell lines and primary tumor samples, to identify associations between epithelial-mesenchymal transition (EMT) and luminal-basal plasticity - two key processes that enable heterogeneity. We show that luminal breast cancer strongly associates with an epithelial cell state, but basal breast cancer is associated with hybrid epithelial/mesenchymal phenotype(s) and higher phenotypic heterogeneity. These patterns were inherent in methylation profiles, suggesting an epigenetic crosstalk between EMT and lineage plasticity in breast cancer. Mathematical modelling of core underlying gene regulatory networks representative of the crosstalk between the luminal-basal and epithelial-mesenchymal axes recapitulate and thus elucidate mechanistic underpinnings of the observed associations from transcriptomic data. Our systems-based approach integrating multi-modal data analysis with mechanism-based modeling offers a predictive framework to characterize intra-tumor heterogeneity and to identify possible interventions to restrict it.

Serine starvation silences estrogen receptor signaling through histone hypoacetylation

Loss of estrogen receptor (ER) pathway activity promotes breast cancer progression, yet how this occurs remains poorly understood. Here, we show that serine starvation, a metabolic stress often found in breast cancer, represses estrogen receptor alpha (ERα) signaling by reprogramming glucose metabolism and epigenetics. Using isotope tracing and time-resolved metabolomic analyses, we demonstrate that serine is required to maintain glucose flux through glycolysis and the TCA cycle to support acetyl-CoA generation for histone acetylation. Consequently, limiting serine depletes histone H3 lysine 27 acetylation (H3K27ac), particularly at the promoter region of ER pathway genes including the gene encoding ERα, ESR1. Mechanistically, serine starvation impairs acetyl-CoA-dependent gene expression by inhibiting the entry of glycolytic carbon into the TCA cycle and down-regulating the mitochondrial citrate exporter SLC25A1, a critical enzyme in the production of nucleocytosolic acetyl-CoA from glucose. Consistent with this model, total H3K27ac and ERα expression are suppressed by SLC25A1 inhibition and restored by acetate, an alternate source of acetyl-CoA, in serine-free conditions. We thus uncover an unexpected role for serine in sustaining ER signaling through the regulation of acetyl-CoA metabolism.

The Role of Obesity in Breast Cancer Pathogenesis

Research has shown that obesity increases the risk for type 2 diabetes mellitus (Type 2 DM) by promoting insulin resistance, increases serum estrogen levels by the upregulation of aromatase, and promotes the release of reactive oxygen species (ROS) by macrophages. Increased circulating glucose has been shown to activate mammalian target of rapamycin (mTOR), a significant signaling pathway in breast cancer pathogenesis. Estrogen plays an instrumental role in estrogen-receptor-positive breast cancers. The role of ROS in breast cancer warrants continued investigation, in relation to both pathogenesis and treatment of breast cancer. We aim to review the role of obesity in breast cancer pathogenesis and novel therapies mediating obesity-associated breast cancer development. We explore the association between body mass index (BMI) and breast cancer incidence and the mechanisms by which oxidative stress modulates breast cancer pathogenesis. We discuss the role of glutathione, a ubiquitous antioxidant, in breast cancer therapy. Lastly, we review breast cancer therapies targeting mTOR signaling, leptin signaling, blood sugar reduction, and novel immunotherapy targets.

Shielding and nurturing: Fibronectin as a modulator of cancer drug resistance

Resistance to chemotherapy and targeted therapies constitute a common hallmark of most cancers and represent a dominant factor fostering tumor relapse and metastasis. Fibronectin, an abundant extracellular matrix glycoprotein, has long been proposed to play an important role in the pathobiology of cancer. Recent research has unraveled the role of Fibronectin in the onset of chemoresistance against a variety of antineoplastic drugs including DNA-damaging agents, hormone receptor antagonists, tyrosine kinase inhibitors, microtubule destabilizing agents, etc. The current review summarizes the role played by Fibronectin in mediating drug resistance against diverse anticancer drugs. We have also discussed how the aberrant expression of Fibronectin drives the oncogenic signaling pathways ultimately leading to drug resistance through the inhibition of apoptosis, promotion of cancer cell growth and proliferation.

Overview of Solid Lipid Nanoparticles in Breast Cancer Therapy

Lipid nanoparticles (LNPs), composed of ionized lipids, helper lipids, and cholesterol, provide general therapeutic effects by facilitating intracellular transport and avoiding endosomal compartments. LNP-based drug delivery has great potential for the development of novel gene therapies and effective vaccines. Solid lipid nanoparticles (SLNs) are derived from physiologically acceptable lipid components and remain robust at body temperature, thereby providing high structural stability and biocompatibility. By enhancing drug delivery through blood vessels, SLNs have been used to improve the efficacy of cancer treatments. Breast cancer, the most common malignancy in women, has a declining mortality rate but remains incurable. Recently, as an anticancer drug delivery system, SLNs have been widely used in breast cancer, improving the therapeutic efficacy of drugs. In this review, we discuss the latest advances of SLNs for breast cancer treatment and their potential in clinical use.

Targeting the Vulnerabilities of Oncogene Activation

Treatment strategies for cancer have progressed greatly in recent decades [...].

Breast cancer: miRNAs monitoring chemoresistance and systemic therapy

With a high mortality rate that accounts for millions of cancer-related deaths each year, breast cancer is the second most common malignancy in women. Chemotherapy has significant potential in the prevention and spreading of breast cancer; however, drug resistance often hinders therapy in breast cancer patients. The identification and the use of novel molecular biomarkers, which can predict response to chemotherapy, might lead to tailoring breast cancer treatment. In this context, accumulating research has reported microRNAs (miRNAs) as potential biomarkers for early cancer detection, and are conducive to designing a more specific treatment plan by helping analyze drug resistance and sensitivity in breast cancer treatment. In this review, miRNAs are discussed in two alternative ways-as tumor suppressors to be used in miRNA replacement therapy to reduce oncogenesis and as oncomirs to lessen the translation of the target miRNA. Different miRNAs like miR-638, miR-17, miR-20b, miR-342, miR-484, miR-21, miR-24, miR-27, miR-23 and miR-200 are involved in the regulation of chemoresistance through diverse genetic targets. For instance, tumor-suppressing miRNAs like miR-342, miR-16, miR-214, and miR-128 and tumor-promoting miRNAs like miR101 and miR-106-25 cluster regulate the cell cycle, apoptosis, epithelial to mesenchymal transition and other pathways to impart breast cancer drug resistance. Hence, in this review, we have discussed the significance of miRNA biomarkers that could assist in providing novel therapeutic targets to overcome potential chemotherapy resistance to systemic therapy and further facilitate the design of tailored therapy for enhanced efficacy against breast cancer.

Therapeutic effects of guanidine hydrochloride on breast cancer through targeting KCNG1 gene

BACKGROUND

Triple-negative breast cancer (TNBC) is one of the subtypes of breast cancer (BC) that is associated with poor survival rates and failure to respond to hormonal and targeted therapies.

OBJECTIVE

The aim of this study was to identify a specific gene at the expression level for TNBC and targeting of this type of breast cancer based on it. Using TCGA database, genes that are particularly high expression in TNBC subtypes compared to other BC subtypes (in terms of receptor status) and normal samples were identified and their sensitivity and specificity were evaluated. Using PharmacoGX and Drug Bank data, drug sensitivity and drug-appropriate genes were identified, respectively. The effects of the identified drug on triple-negative cell lines (MDA-MB-468) were evaluated in comparison with the cell line of other subtypes (MCF7) by apoptosis and MTS tests.

RESULTS

Data analyzes showed that the expression level of KCNG1 gene in the TNBC subgroup was significantly higher compared to other BC subtypes from the KCN gene family and ROC results showed that this gene had highest sensitivity and specificity in TNBC subtype. The results of drug resistance and sensitivity showed that an increase in the expression level of KCNG1 was associated with sensitivity to Cisplatin and Oxaliplatin. Moreover, Drug Bank results showed that Guanidine hydrochloride (GuHCl) was a suitable inhibitor for KCNG1. In vitro results showed that the expression level of KCNG1 was higher in MDA-MB-468 compared to MCF7. In addition, the rate of apoptosis in response to GuHCl treatment in MDA-MB-468 cell line as TNBC cell model was higher than MCF7 in the same concentration.

CONCLUSION

This study revealed that GuHCl could be a suitable treatment for TNBC subtype by targeting of KCNG1.

Recent Advancement in Breast Cancer Research: Insights from Model Organisms-Mouse Models to Zebrafish

Animal models have been utilized for decades to investigate the causes of human diseases and provide platforms for testing novel therapies. Indeed, breakthrough advances in genetically engineered mouse (GEM) models and xenograft transplantation technologies have dramatically benefited in elucidating the mechanisms underlying the pathogenesis of multiple diseases, including cancer. The currently available GEM models have been employed to assess specific genetic changes that underlay many features of carcinogenesis, including variations in tumor cell proliferation, apoptosis, invasion, metastasis, angiogenesis, and drug resistance. In addition, mice models render it easier to locate tumor biomarkers for the recognition, prognosis, and surveillance of cancer progression and recurrence. Furthermore, the patient-derived xenograft (PDX) model, which involves the direct surgical transfer of fresh human tumor samples to immunodeficient mice, has contributed significantly to advancing the field of drug discovery and therapeutics. Here, we provide a synopsis of mouse and zebrafish models used in cancer research as well as an interdisciplinary 'Team Medicine' approach that has not only accelerated our understanding of varied aspects of carcinogenesis but has also been instrumental in developing novel therapeutic strategies.

BRK confers tamoxifen-resistance in breast cancer via regulation of tyrosine phosphorylation of CDK1

Tamoxifen (Tam) has been the first-line therapy for estrogen receptor-positive breast cancer since its FDA-approval in 1998. Tam-resistance, however, presents a challenge and the mechanisms that drive it have yet to be fully elucidated. The non-receptor tyrosine kinase BRK/PTK6 is a promising candidate as previous research has shown that BRK knockdown resensitizes Tam-resistant breast cancer cells to the drug. However, the specific mechanisms that drive its importance to resistance remain to be investigated. Here, we investigate the role and mechanism of action of BRK in Tam-resistant (TamR), ER+, and T47D breast cancer cells using phosphopeptide enrichment and high throughput phopshoproteomics analysis. We conducted BRK-specific shRNA knockdown in TamR T47D cells and compared phosphopeptides identified in these cells with their Tam-resistant counterpart and parental, Tam-sensitive cells (Par). A total of 6492 STY phosphosites were identified. Of these sites, 3739 high-confidence pST sites and 118 high-confidence pY sites were analyzed for significant changes in phosphorylation levels to identify pathways that were differentially regulated in TamR versus Par and to investigate changes in these pathways when BRK is knocked down in TamR. We observed and validated increased CDK1 phosphorylation at Y15 in TamR cells compared to BRK-depleted TamR cells. Our data suggest that BRK is a potential Y15-directed CDK1 regulatory kinase in Tam-resistant breast cancer.

Targeting mitochondria as a potential therapeutic strategy against chemoresistance in cancer

The importance of mitochondria is not only limited to energy generation but also in several physical and chemical processes critical for cell survival. Mitochondria play an essential role in cellular apoptosis, calcium ion transport and cellular metabolism. Mutation in the nuclear and mitochondrial genes, altered oncogenes/tumor suppressor genes, and deregulated signalling for cell viability are major reasons for cancer progression and chemoresistance. The development of drug resistance in cancer patients is a major challenge in cancer treatment as the resistant cells are often more aggressive. The drug resistant cells of numerous cancer types exhibit the deregulation of mitochondrial function. The increased biogenesis of mitochondria and its dynamic alteration contribute to developing resistance. Further, a small subpopulation of cancer stem cells in the heterogeneous tumor is primarily responsible for chemoresistance and has an attribute of mitochondrial dysfunction. This review highlights the critical role of mitochondrial dysfunction in chemoresistance in cancer cells through the processes of apoptosis, autophagy/mitophagy, and cancer stemness. Mitochondria-targeted therapeutic strategies might help reduce cancer progression and chemoresistance induced by various cancer drugs.

2D-CuPd nanozyme overcome tamoxifen resistance in breast cancer by regulating the PI3K/AKT/mTOR pathway

Tamoxifen is the most commonly used treatment for estrogen-receptor (ER) positive breast cancer patients, but its efficacy is severely hampered by resistance. PI3K/AKT/mTOR pathway inhibition was proven to augment the benefit of endocrine therapy and exhibited potential for reversing tamoxifen-induced resistance. However, the vast majority of PI3K inhibitors currently approved for clinical use are unsatisfactory in terms of safety and efficacy. We developed two-dimensional CuPd (2D-CuPd) nanosheets with oxidase and peroxidase nanozyme activities to offer a novel solution to inhibit the activity of the PI3K/AKT/mTOR pathway. 2D-CuPd exhibit superior dual nanozyme activities converting hydrogen peroxide accumulated in drug-resistant cells into more lethal hydroxyl radicals while compensating for the insufficient superoxide anion produced by tamoxifen. The potential clinical utility was further demonstrated in an orthotopically implanted tamoxifen-resistant PDX breast cancer model. Our results reveal a novel nanozyme ROS-mediated protein mechanism for the regulation of the PI3K subunit, illustrate the cellular pathways through which increased p85β protein expression contributes to tamoxifen resistance, and reveal p85β protein as a potential therapeutic target for overcoming tamoxifen resistance. 2D-CuPd is the first reported nanomaterial capable of degrading PI3K subunits, and its high performance combined with further materials engineering may lead to the development of nanozyme-based tumor catalytic therapy.

The RUNX/CBFβ Complex in Breast Cancer: A Conundrum of Context

Dissecting and identifying the major actors and pathways in the genesis, progression and aggressive advancement of breast cancer is challenging, in part because neoplasms arising in this tissue represent distinct diseases and in part because the tumors themselves evolve. This review attempts to illustrate the complexity of this mutational landscape as it pertains to the RUNX genes and their transcription co-factor CBFβ. Large-scale genomic studies that characterize genetic alterations across a disease subtype are a useful starting point and as such have identified recurring alterations in CBFB and in the RUNX genes (particularly RUNX1). Intriguingly, the functional output of these mutations is often context dependent with regards to the estrogen receptor (ER) status of the breast cancer. Therefore, such studies need to be integrated with an in-depth understanding of both the normal and corrupted function in mammary cells to begin to tease out how loss or gain of function can alter the cell phenotype and contribute to disease progression. We review how alterations to RUNX/CBFβ function contextually ascribe to breast cancer subtypes and discuss how the in vitro analyses and mouse model systems have contributed to our current understanding of these proteins in the pathogenesis of this complex set of diseases.

Liver X Receptor Inverse Agonist GAC0001E5 Impedes Glutaminolysis and Disrupts Redox Homeostasis in Breast Cancer Cells

Liver X receptors (LXRs) are members of the nuclear receptor family of ligand-dependent transcription factors which regulate the expression of lipid and cholesterol metabolism genes. Moreover, LXRs and their ligands have been shown to inhibit tumor growth in a variety of cancers. We have previously identified the small molecule compound GAC0001E5 (1E5) as an LXR inverse agonist and a potent inhibitor of pancreatic cancer cells. Transcriptomic and metabolomic studies showed that 1E5 disrupts glutamine metabolism, an essential metabolic pathway commonly reprogrammed during malignant transformation, including in breast cancers. To determine the role of LXRs and potential application of 1E5 in breast cancer, we examined LXR expression in publicly available clinical samples, and found that LXR expression is elevated in breast tumors as compared to normal tissues. In luminal A, endocrine therapy-resistant, and triple-negative breast cancer cells, 1E5 exhibited LXR inverse agonist and "degrader" activity and strongly inhibited cell proliferation and colony formation. Treatments with 1E5 downregulated the transcription of key glutaminolysis genes, and, correspondingly, biochemical assays indicated that 1E5 lowered intracellular glutamate and glutathione levels and increased reactive oxygen species. These results indicate that novel LXR ligand 1E5 is an inhibitor of glutamine metabolism and redox homeostasis in breast cancers and suggest that modulating LXR activity and expression in tumor cells is a promising strategy for targeting metabolic reprogramming in breast cancer therapeutics.

GDNF-RET signaling and EGR1 form a positive feedback loop that promotes tamoxifen resistance via cyclin D1

BACKGROUND

Rearranged during transfection (RET) tyrosine kinase signaling has been previously implicated in endocrine resistant breast cancer, however the mechanism by which this signaling cascade promotes resistance is currently not well described. We recently reported that glial cell-derived neurotrophic factor (GDNF)-RET signaling appears to promote a positive feedback loop with the transcription factor early growth response 1 (EGR1). Here we investigate the mechanism behind this feedback loop and test the hypothesis that GDNF-RET signaling forms a regulatory loop with EGR1 to upregulate cyclin D1 (CCND1) transcription, leading to cell cycle progression and tamoxifen resistance.

METHODS

To gain a better understanding of the GDNF-RET-EGR1 resistance mechanism, we studied the GDNF-EGR1 positive feedback loop and the role of GDNF and EGR1 in endocrine resistance by modulating their transcription levels using CRISPR-dCAS9 in tamoxifen sensitive (TamS) and tamoxifen resistant (TamR) MCF-7 cells. Additionally, we performed kinetic studies using recombinant GDNF (rGDNF) treatment of TamS cells. Finally, we performed cell proliferation assays using rGDNF, tamoxifen (TAM), and Palbociclib treatments in TamS cells. Statistical significance for qPCR and chromatin immunoprecipitation (ChIP)-qPCR experiments were determined using a student's paired t-test and statistical significance for the cell viability assay was a one-way ANOVA.

RESULTS

GDNF-RET signaling formed a positive feedback loop with EGR1 and also downregulated estrogen receptor 1 (ESR1) transcription. Upregulation of GDNF and EGR1 promoted tamoxifen resistance in TamS cells and downregulation of GDNF promoted tamoxifen sensitivity in TamR cells. Additionally, we show that rGDNF treatment activated GDNF-RET signaling in TamS cells, leading to recruitment of phospho-ELK-1 to the EGR1 promoter, upregulation of EGR1 mRNA and protein, binding of EGR1 to the GDNF and CCND1 promoters, increased GDNF protein expression, and subsequent upregulation of CCND1 mRNA levels. We also show that inhibition of cyclin D1 with Palbociclib, in the presence of rGDNF, decreases cell proliferation and resensitizes cells to TAM.

CONCLUSION

Outcomes from these studies support the hypotheses that GDNF-RET signaling forms a positive feedback loop with the transcription factor EGR1, and that GDNF-RET-EGR1 signaling promotes endocrine resistance via signaling to cyclin D1. Inhibition of components of this signaling pathway could lead to therapeutic insights into the treatment of endocrine resistant breast cancer.

Cellular and molecular basis of therapeutic approaches to breast cancer

In recent decades, there has been a significant amount of research into breast cancer, with some important breakthroughs in the treatment of both primary and metastatic breast cancers. It's a well-known fact that treating breast cancer is still a challenging endeavour even though physicians have a fantastic toolset of the latest treatment options at their disposal. Due to limitations of current clinical treatment options, traditional chemotherapeutic drugs, and surgical options are still required to address this condition. In recent years, there have been several developments resulting in a wide range of treatment options. This review article discusses the cellular and molecular foundation of chemotherapeutic drugs, endocrine system-based treatments, biological therapies, gene therapy, and innovative techniques for treating breast cancer.

GPER-mediated stabilization of HIF-1α contributes to upregulated aerobic glycolysis in tamoxifen-resistant cells

Tamoxifen is a first-line therapeutic drug for oestrogen-receptor positive breast cancer; however, like other therapeutics, its clinical use is limited by acquired resistance. Tamoxifen-resistant cells have demonstrated enhanced aerobic glycolysis; however, the mechanisms underlying this upregulation remain unclear. Here, we demonstrated that G-protein coupled oestrogen receptor (GPER) was involved in the upregulation of aerobic glycolysis via induction of hypoxia-inducible factor-1α (HIF-1α) expression and transcriptional activity in tamoxifen-resistant cells. Additionally, GPER stabilized HIF-1α through inhibiting its hydroxylation and ubiquitin-mediated degradation, which were associated with upregulation of C-terminal hydrolase-L1 (UCH-L1), downregulation of prolyl hydroxylase 2 (PHD2) and von Hippel-Lindau tumour suppressor protein (pVHL), induction of HIF-1α/UCH-L1 interaction, and suppression of HIF-1α/PHD2-pVHL association. The GPER/HIF-1α axis was functionally responsible for regulating tamoxifen sensitivity both in vitro and in vivo. Moreover, there was a positive correlation between GPER and HIF-1α expression in clinical breast cancer tissues, and high levels of GPER combined with nuclear HIF-1α indicated poor overall survival. High levels of the GPER/HIF-1α axis were also correlated with shorter relapse-free survival in patients receiving tamoxifen. Hence, our findings support a critical role of GPER/HIF-1α axis in the regulation of aerobic glycolysis in tamoxifen-resistant cells, offering a potential therapeutic target for tamoxifen-resistant breast cancer.

Mesoporous Silica Nanoparticles Enhance the Anticancer Efficacy of Platinum(IV)-Phenolate Conjugates in Breast Cancer Cell Lines

The main reasons for the limited clinical efficacy of the platinum(II)-based agent cisplatin include drug resistance and significant side effects. Due to their better stability, as well as the possibility to introduce biologically active ligands in their axial positions constructing multifunctional prodrugs, creating platinum(IV) complexes is a tempting strategy for addressing these limitations. Another strategy for developing chemotherapeutics with lower toxicity relies on the ability of nanoparticles to accumulate in greater quantities in tumor tissues through passive targeting. To combine the two approaches, three platinum(IV) conjugates based on a cisplatin scaffold containing in the axial positions derivatives of caffeic and ferulic acid were prepared and loaded into SBA-15 to produce the corresponding mesoporous silica nanoparticles (MSNs). The free platinum(IV) conjugates demonstrated higher or comparable activity with respect to cisplatin against different human breast cancer cell lines, while upon immobilization, superior antiproliferative activity with markedly increased cytotoxicity (more than 1000-fold lower IC50 values) compared to cisplatin was observed. Mechanistic investigations with the most potent conjugate, cisplatin-diacetyl caffeate (1), and the corresponding MSNs (SBA-15|1) in a 4T1 mouse breast cancer cell line showed that these compounds induce apoptotic cell death causing strong caspase activation. In vivo, in BALB/c mice, 1 and SBA-15|1 inhibited the tumor growth while decreasing the necrotic area and lowering the mitotic rate.

Labeling of a mutant estrogen receptor with an Affimer in a breast cancer cell line

Mutations of the intracellular estrogen receptor alpha (ERα) is implicated in 70% of breast cancers. Therefore, it is of considerable interest to image various mutants (L536S, Y537S, D538G) in living cancer cell lines, particularly as a function of various anticancer drugs. We therefore developed a small (13 kDa) Affimer, which, after fluorescent labeling, is able to efficiently label ERα by traveling through temporary pores in the cell membrane, created by the toxin streptolysin O. The Affimer, selected by a phage display, predominantly labels the Y537S mutant and can tell the difference between L536S and D538G mutants. The vast majority of Affimer-ERαY537S is in the nucleus and is capable of an efficient, unrestricted navigation to its target DNA sequence, as visualized by single-molecule fluorescence. The Affimer can also differentiate the effect of selective estrogen receptor modulators. More generally, this is an example of a small binding reagent-an Affimer protein-that can be inserted into living cells with minimal perturbation and high efficiency, to image an endogenous protein.

Cancer-associated fibroblasts: Origin, function, imaging, and therapeutic targeting

The tumor microenvironment (TME) is emerging as one of the primary barriers in cancer therapy. Cancer-associated fibroblasts (CAF) are a common inhabitant of the TME in several tumor types and play a critical role in tumor progression and drug resistance via different mechanisms such as desmoplasia, angiogenesis, immune modulation, and cancer metabolism. Due to their abundance and significance in pro-tumorigenic mechanisms, CAF are gaining attention as a diagnostic target as well as to improve the efficacy of cancer therapy by their modulation. In this review, we highlight existing imaging techniques that are used for the visualization of CAF and CAF-induced fibrosis and provide an overview of compounds that are known to modulate CAF activity. Subsequently, we also discuss CAF-targeted and CAF-modulating nanocarriers. Finally, our review addresses ongoing challenges and provides a glimpse into the prospects that can spearhead the transition of CAF-targeted therapies from opportunity to reality.

Xanthorrhizol, a potential anticancer agent, from Curcuma xanthorrhiza Roxb

BACKGROUND

Xanthorrhizol (XTZ), a bisabolene sesquiterpenoid, is abundantly found in the plant Curcuma xanthorrhiza Roxb. Traditionally, C. xanthorrhiza is widely used for the treatment of different health conditions, including common fever, infection, lack of appetite, fatigue, liver complaints, and gastrointestinal disorders. XTZ exhibits wide-ranging pharmacological activities, including anticancer, antioxidative, anti-inflammatory, antimicrobial, and antidiabetic activities, in addition to a protective effect on multiple organs. The present review provides detailed findings on the anticancer activities of XTZ and the underlying cellular and molecular mechanisms.

METHODS

Literature was searched systematically in main databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, with keywords "tumor AND xanthorrhizol" or "cancer AND xanthorrhizol".

RESULTS

Studies show that XTZ has preventive and therapeutic activities against different types of cancer, including breast, cervical, colon, liver, lung, oral and esophageal, and skin cancers. XTZ regulates multiple signaling pathways that block carcinogenesis and proliferation. In vitro and in vivo studies showed that XTZ targets different kinases, inflammatory cytokines, apoptosis proteins, and transcription factors, leading to the suppression of angiogenesis, metastasis, and the activation of apoptosis and cell cycle arrest.

CONCLUSION

The potential anticancer benefits of XTZ recommend further in vivo studies against different types of cancer. Further, XTZ needs to be confirmed for its toxicity, bioavailability, protective, antifatigue, and energy booster activities. Future studies for the therapeutic development of XTZ may be directed to cancer-related fatigue.

Effects of Combined Pentadecanoic Acid and Tamoxifen Treatment on Tamoxifen Resistance in MCF−7/SC Breast Cancer Cells

Estrogen receptors are indicators of breast cancer adaptability to endocrine therapies, such as tamoxifen. Deficiency or absence of estrogen receptor α (ER−α) in breast cancer cells results in reduced efficacy of endocrine therapy. Here, we investigated the effect of combined tamoxifen and pentadecanoic acid therapy on ER−α−under−expressing breast cancer cells. Drug resistance gene expression patterns were determined by RNA sequencing analysis and in vitro experiments. For the first time, we demonstrate that the combined treatment of pentadecanoic acid, an odd−chain fatty acid, and tamoxifen synergistically suppresses the growth of human breast carcinoma MCF−7 stem cells (MCF−7/SCs), which were found to be tamoxifen−resistant and showed reduced ER−α expression compared with the parental MCF−7 cells. In addition, the combined treatment synergistically induced apoptosis and accumulation of sub−G1 cells and suppressed epithelial−to−mesenchymal transition (EMT). Exposure to this combination induces re−expression of ER−α at the transcriptional and protein levels, along with suppression of critical survival signal pathways, such as ERK1/2, MAPK, EGFR, and mTOR. Collectively, decreased ER−α expression was restored by pentadecanoic acid treatment, resulting in reversal of tamoxifen resistance. Overall, pentadecanoic acid exhibits the potential to enhance the efficacy of endocrine therapy in the treatment of ER−α−under−expressing breast cancer cells.

Combinatorial treatments of tamoxifen and SM6Met, an extract from Cyclopia subternata Vogel, are superior to either treatment alone in MCF-7 cells

Synergistic drug combinations are not only popular in antibiotic, anti-microbial, immune disease (i.e., AIDS) and viral infection studies, but has also gained traction in the field of cancer research as a multi-targeted approach. It has the potential to lower the doses needed of standard of care (SOC) therapeutic agents, whilst maintaining an effective therapeutic level. Lower dosages could ameliorate the fundamental problems such as drug resistance and metastasis associated with current SOC therapies. In the current study, we show that the combination of SM6Met with (2)-4-hydroxytamoxifen (4-OH-Tam, the active metabolite of tamoxifen) produces a strong synergistic effect in terms of inhibiting MCF7 ER-positive (ER⁺) breast cancer cell proliferation and that a 20 times lower dose of 4-OH-Tam in combination with SM6Met is required to produce the same inhibitory effect on cell proliferation as 4-OH-Tam on its own. Cell cycle analyses of the best combination ratios of SM6Met and 4-OH-Tam also suggests that the combination results in increased accumulation of cells in the S-phase and in the apoptotic phase. Moreover, the best combination ratio (20:1) of SM6Met with 4-OH-Tam displayed greater anti-metastatic potential in terms of inhibiting ER⁺ breast cancer cell migration, invasion, and colony formation than the SOC therapy alone, suggesting that SM6Met together with 4-OH-Tam could be a viable drug combination for not only delaying resistance and ameliorating the negative side-effects associated with current SOC therapies, like tamoxifen, but could also provide a novel, more affordable therapeutic alternative for treating or preventing ER⁺ breast cancer metastasis.

Clinical significance and prognostic value of small nucleolar RNA SNORA38 in breast cancer

Background

Breast cancer is the most common malignant tumor among women worldwide, and breast cancer stem cells (BCSCs) are believed to be the source of tumorigenesis. New findings suggest that small nucleolar RNAs (snoRNAs) play a significant role in tumor development.

Methods

The Cancer Genome Atlas (TCGA) and Kaplan–Meier survival analysis were used to demonstrate expression and survival of SNORA38 signature. In situ hybridization (ISH) and immunohistochemical (IHC) were conducted to analyze the correlation between SNORA38 and stemness biomarker in 77 BC samples. Gene Set Enrichment Analysis (GSEA) was performed to investigate the mechanisms related to SNORA38 expression in BC. Real-time qPCR was employed to evaluate the expression of SNORA38 in breast cancer cell lines.

Results

In the public database and patients’ biopsies, SNORA38 was significantly up-regulated in breast cancer. Furthermore, the expression of SNORA38 was significantly correlated with tumor size, lymph node metastasis, and TNM stage, among which tumor size was an independent factor for SNORA38 expression. Higher SNORA38 expression was associated with shorter overall survival (OS). Meanwhile, SNORA38 was positively associated with the stem cell marker OCT-4, which suggested that SNORA38 might be related to breast cancer stemness.

Conclusions

SNORA38 is an important carcinogenic snoRNA in breast cancer and might be a prognostic biomarker for breast cancer.

The role of CircRNA/miRNA/mRNA axis in breast cancer drug resistance

Multidrug resistance is one of the major obstacles in the treatment of cancers. This undesirable feature increases the mortality rate of cancers, including breast cancer. Circular RNA (CircRNA)/microRNA (miRNA)/messenger RNA (mRNA) is one of the important axes with major roles in the promotion and resistance of breast cancer. This heterogeneous pathway includes mRNA of oncogenes and tumor suppressors, which are controlled by miRNAs and CircRNAs. Unfortunately, this network could be easily deregulated, resulting in drug resistance and tumor development. Therefore, understanding these dysregulations may thus help to identify effective therapeutic targets. On this basis, we try to review the latest findings in the field, which could help us to better comprehend this significant axis in breast cancer.

Detection of relevant pharmacogenetic information through exome sequencing in oncology

Background: Germline sequencing of individual genomes can detect alleles responsible for adverse drug reactions (ADRs) in relation to chemotherapy, targeted agents, antiemetics or pain treatment. Materials & methods: To evaluate the interest of such pharmacogenetic information, the authors retrospectively analyzed genes known to have an impact on cancer therapy in a cohort of 445 solid cancers patients. Results: Six patients treated with 5-fluorouracil carrying one DPYD variant classified as 1A showed decreased drug mean clearance (p = 0.01). Regarding CYP2D6, all patients (n = 5) with predicted CYP2D6 poor or ultra-rapid metabolizer status experienced adverse drug reactions related to opioid therapy. Conclusion: Genomic germline sequencing performed for theragnostic issues in patients with a solid tumor, can provide relevant information about common pharmacogenetic alleles.