Suppression of invasion and metastasis of triple-negative breast cancer lines by pharmacological or genetic inhibition of slug activity

Triple-Negative Breast Cancer Progression and Drug Resistance in the Context of Epithelial-Mesenchymal Transition

Triple-negative breast cancer (TNBC) is one of the most difficult subtypes of breast cancer to treat due to its distinct clinical and molecular characteristics. Patients with TNBC face a high recurrence rate, an increased risk of metastasis, and lower overall survival compared to other breast cancer subtypes. Despite advancements in targeted therapies, traditional chemotherapy (primarily using platinum compounds and taxanes) continues to be the standard treatment for TNBC, often with limited long-term efficacy. TNBC tumors are heterogeneous, displaying a diverse mutation profile and considerable chromosomal instability, which complicates therapeutic interventions. The development of chemoresistance in TNBC is frequently associated with the process of epithelial-mesenchymal transition (EMT), during which epithelial tumor cells acquire a mesenchymal-like phenotype. This shift enhances metastatic potential, while simultaneously reducing the effectiveness of standard chemotherapeutics. It has also been suggested that EMT plays a central role in the development of cancer stem cells. Hence, there is growing interest in exploring small-molecule inhibitors that target the EMT process as a future strategy for overcoming resistance and improving outcomes for patients with TNBC. This review focuses on the progression and drug resistance of TNBC with an emphasis on the role of EMT in these processes. We present TNBC-specific and EMT-related molecular features, key EMT protein markers, and various signaling pathways involved. We also discuss other important mechanisms and factors related to chemoresistance in TNBC within the context of EMT, highlighting treatment advancements to improve patients' outcomes.

Caspase-9 suppresses metastatic behavior of MDA-MB-231 cells in an adaptive organoid model

Caspase-9, a cysteine-aspartate protease traditionally associated with intrinsic apoptosis, has recently emerged as having non-apoptotic roles, including influencing cell migration-an aspect that has received limited attention in existing studies. In our investigation, we aimed to explore the impact of caspase-9 on the migration and invasion behaviors of MDA-MB-231, a triple-negative breast cancer (TNBC) cell line known for its metastatic properties. We established a stable cell line expressing an inducible caspase-9 (iC9) in MDA-MB-231 and assessed their metastatic behavior using both monolayer and the 3D organotypic model in co-culture with human Foreskin fibroblasts (HFF). Our findings revealed that caspase-9 had an inhibitory effect on migration and invasion in both models. In monolayer culture, caspase-9 effectively suppressed the migration and invasion of MDA-MB-231 cells, comparable to the anti-metastatic agent panitumumab (Pan). Notably, the combination of caspase-9 and Pan exhibited a significant additional effect in reducing metastatic behavior. Interestingly, caspase-9 demonstrated superior efficacy compared to Pan in the organotypic model. Molecular analysis showed down regulation of epithelial-mesenchymal transition and migratory markers, in caspase-9 activated cells. Additionally, flow cytometry analysis indicated a cell cycle arrest. Moreover, pre-treatment with activated caspase-9 sensitized cells to the chemotherapy of doxorubicin, thereby enhancing its effectiveness. In conclusion, the anti-metastatic potential of caspase-9 presents avenues for the development of novel therapeutic approaches for TNBC/metastatic breast cancer. Although more studies need to figure out the exact involving mechanisms behind this behavior.

LSD1 in drug discovery: From biological function to clinical application

Lysine-specific demethylase 1 (LSD1) is a flavin adenine dinucleotide (FAD) dependent monoamine oxidase (MAO) that erases the mono-, and dimethylation of histone 3 lysine 4 (H3K4), resulting in the suppression of target gene transcriptions. Besides, it can also demethylate some nonhistone substrates to regulate their biological functions. As reported, LSD1 is widely upregulated and plays a key role in several kinds of cancers, pharmacological or genetic ablation of LSD1 in cancer cells suppresses cell aggressiveness by several distinct mechanisms. Therefore, numerous LSD1 inhibitors, including covalent and noncovalent, have been developed and several of them have entered clinical trials. Herein, we systemically reviewed and discussed the biological function of LSD1 in tumors, lymphocytes as well as LSD1-targeting inhibitors in clinical trials, hoping to benefit the field of LSD1 and its inhibitors.

Role of forkhead box proteins in regulation of doxorubicin and paclitaxel responses in tumor cells: A comprehensive review

Chemotherapy is one of the common first-line therapeutic methods in cancer patients. Despite the significant effects in improving the quality of life and survival of patients, chemo resistance is observed in a significant part of cancer patients, which leads to tumor recurrence and metastasis. Doxorubicin (DOX) and paclitaxel (PTX) are used as the first-line drugs in a wide range of tumors; however, DOX/PTX resistance limits their use in cancer patients. Considering the DOX/PTX side effects in normal tissues, identification of DOX/PTX resistant cancer patients is required to choose the most efficient therapeutic strategy for these patients. Investigating the molecular mechanisms involved in DOX/PTX response can help to improve the prognosis in cancer patients. Several cellular processes such as drug efflux, autophagy, and DNA repair are associated with chemo resistance that can be regulated by transcription factors as the main effectors in signaling pathways. Forkhead box (FOX) family of transcription factor has a key role in regulating cellular processes such as cell differentiation, migration, apoptosis, and proliferation. FOX deregulations have been associated with resistance to chemotherapy in different cancers. Therefore, we discussed the role of FOX protein family in DOX/PTX response. It has been reported that FOX proteins are mainly involved in DOX/PTX response by regulation of drug efflux, autophagy, structural proteins, and signaling pathways such as PI3K/AKT, NF-kb, and JNK. This review is an effective step in introducing the FOX protein family as the reliable prognostic markers and therapeutic targets in cancer patients.

Copper chelation suppresses epithelial-mesenchymal transition by inhibition of canonical and non-canonical TGF-β signaling pathways in cancer

BACKGROUND

Metastatic cancer cells exploit Epithelial-mesenchymal-transition (EMT) to enhance their migration, invasion, and resistance to treatments. Recent studies highlight that elevated levels of copper are implicated in cancer progression and metastasis. Clinical trials using copper chelators are associated with improved patient survival; however, the molecular mechanisms by which copper depletion inhibits tumor progression and metastasis are poorly understood. This remains a major hurdle to the clinical translation of copper chelators. Here, we propose that copper chelation inhibits metastasis by reducing TGF-β levels and EMT signaling. Given that many drugs targeting TGF-β have failed in clinical trials, partly because of severe side effects arising in patients, we hypothesized that copper chelation therapy might be a less toxic alternative to target the TGF-β/EMT axis.

RESULTS

Our cytokine array and RNA-seq data suggested a link between copper homeostasis, TGF-β and EMT process. To validate this hypothesis, we performed single-cell imaging, protein assays, and in vivo studies. Here, we used the copper chelating agent TEPA to block copper trafficking. Our in vivo study showed a reduction of TGF-β levels and metastasis to the lung in the TNBC mouse model. Mechanistically, TEPA significantly downregulated canonical (TGF-β/SMAD2&3) and non-canonical (TGF-β/PI3K/AKT, TGF-β/RAS/RAF/MEK/ERK, and TGF-β/WNT/β-catenin) TGF-β signaling pathways. Additionally, EMT markers of MMP-9, MMP-14, Vimentin, β-catenin, ZEB1, and p-SMAD2 were downregulated, and EMT transcription factors of SNAI1, ZEB1, and p-SMAD2 accumulated in the cytoplasm after treatment.

CONCLUSIONS

Our study suggests that copper chelation therapy represents a potentially effective therapeutic approach for targeting TGF-β and inhibiting EMT in a diverse range of cancers.

Role of epithelial-mesenchymal transition factor SNAI1 and its targets in ovarian cancer aggressiveness

Ovarian cancer remains the most lethal gynecologic malignancy in the USA. For over twenty years, epithelial-mesenchymal transition (EMT) has been characterized extensively in development and disease. The dysregulation of this process in cancer has been identified as a mechanism by which epithelial tumors become more aggressive, allowing them to survive and invade distant tissues. This occurs in part due to the increased expression of the EMT transcription factor, SNAI1 (Snail). In the case of epithelial ovarian cancer, Snail has been shown to contribute to cancer invasion, stemness, chemoresistance, and metabolic changes. Thus, in this review, we focus on summarizing current findings on the role of EMT (specifically, factors downstream of Snail) in determining ovarian cancer aggressiveness.

Targeting ARHGEF12 promotes neuroblastoma differentiation, MYCN degradation, and reduces tumorigenicity

PURPOSE

Neuroblastoma arises from developmental block of embryonic neural crest cells and is one of the most common and deadly pediatric tumors. However, the mechanism underlying this block is still unclear. Here, we show that targeting Rho guanine nucleotide exchange factor 12 (ARHGEF12, also named LARG) promotes MYCN degradation and neuroblastoma differentiation, leading to reduced neuroblastoma malignancy.

METHODS

The neuroblastoma TARGET dataset was downloaded to assess ARHGEF12 expression. Cell differentiation, proliferation, colony formation and cell migration analyses were performed to investigate the effects of ARHGEF12 knockdown on neuroblastoma cells. Western blotting and immunohistochemistry were employed to determine protein expression. Animal xenograft models were used to investigate antitumor effects after ARHGEF12 knockdown or treatment with the ARHGEF12 inhibitor Y16 in vivo.

RESULTS

We found that the expression level of ARHGEF12 was higher in neuroblastoma than in better-differentiated ganglioneuroblastoma. Knockdown of ARHGEF12 promoted neuroblastoma differentiation, decreased stemness-related gene expression, and increased differentiation-related gene expression. ARHGEF12 knockdown reduced tumor growth, and the resulting tumors showed bigger tumor cells compared to those in control neuroblastoma xenografts. In addition, it was found that ARHGEF12 knockdown promoted MYCN ubiquitination and degradation in MYCN-amplified tumors through RhoA/ROCK/GSK3β signaling. Targeting ARHGEF12 with the small molecular inhibitor Y16 induced cell differentiation and attenuated neuroblastoma tumorigenicity.

CONCLUSION

Our findings provide new insight into the mechanism by which ARHGEF12 regulates neuroblastoma tumorigenicity and suggest a translatable therapeutic approach by targeting ARHGEF12 with a small molecular inhibitor.

Kalkitoxin: A Potent Suppressor of Distant Breast Cancer Metastasis

Bone metastasis resulting from advanced breast cancer causes osteolysis and increases mortality in patients. Kalkitoxin (KT), a lipopeptide toxin derived from the marine cyanobacterium Moorena producens (previously Lyngbya majuscula), has an anti-metastatic effect on cancer cells. We verified that KT suppressed cancer cell migration and invasion in vitro and in animal models in the present study. We confirmed that KT suppressed osteoclast-soup-derived MDA-MB-231 cell invasion in vitro and induced osteolysis in a mouse model, possibly enhancing/inhibiting metastasis markers. Furthermore, KT inhibits CXCL5 and CXCR2 expression, suppressing the secondary growth of breast cancer cells on the bone, brain, and lungs. The breast-cancer-induced osteolysis in the mouse model further reveals that KT plays a protective role, judging by micro-computed tomography and immunohistochemistry. We report for the first time the novel suppressive effects of KT on cancer cell migration and invasion in vitro and on MDA-MB-231-induced bone loss in vivo. These results suggest that KT may be a potential therapeutic drug for the treatment of breast cancer metastasis.

Targeting the LSD1/KDM1 Family of Lysine Demethylases in Cancer and Other Human Diseases

Lysine-specific demethylase 1 (LSD1) was the first histone demethylase discovered and the founding member of the flavin-dependent lysine demethylase family (KDM1). The human KDM1 family includes KDM1A and KDM1B, which primarily catalyze demethylation of histone H3K4me1/2. The KDM1 family is involved in epigenetic gene regulation and plays important roles in various biological and disease pathogenesis processes, including cell differentiation, embryonic development, hormone signaling, and carcinogenesis. Malfunction of many epigenetic regulators results in complex human diseases, including cancers. Regulators such as KDM1 have become potential therapeutic targets because of the reversibility of epigenetic control of genome function. Indeed, several classes of KDM1-selective small molecule inhibitors have been developed, some of which are currently in clinical trials to treat various cancers. In this chapter, we review the discovery, biochemical, and molecular mechanisms, atomic structure, genetics, biology, and pathology of the KDM1 family of lysine demethylases. Focusing on cancer, we also provide a comprehensive summary of recently developed KDM1 inhibitors and related preclinical and clinical studies to provide a better understanding of the mechanisms of action and applications of these KDM1-specific inhibitors in therapeutic treatment.

Tumour budding is a novel marker in breast cancer: the clinical application and future prospects

Breast cancer (BC) is a group of markedly heterogeneous tumours. There are many subtypes with different biological behaviours and clinicopathological characteristics, leading to significantly different prognosis. Despite significant advances in the treatment of BC, early metastatic is a critical factor for poor prognosis in BC patients. Tumour budding (TB) is considered as the first step process of tumour metastasis and is related to the epithelial-mesenchymal transition (EMT). TB has been observed in a variety of cancers, such as colorectal and gastric cancer, and had been considered as a distinct clinicopathological characteristics for early metastasis. However, TB evaluation standards and clinical application are not uniform in BC, as well as its molecular mechanism is not fully understood. Here, we reviewed the interpretation criteria, mechanism, clinicopathological characteristics and clinical application prospects of TB in BC. Key messagesCurrently, tumour budding is a poor prognosis for various solid tumours, also in breast cancer.Tumour budding is based on epithelial-mesenchymal transition and tumour microenvironment factors and is presumed to be an early step in the metastatic process.Breast cancer tumour budding still needs multi-centre experiments. We summarize the current research on breast cancer tumour budding, analyse the method of discriminating breast cancer tumour budding and explore the prognostic role and mechanism in breast cancer.

A combination of novel NSC small molecule inhibitor along with doxorubicin inhibits proliferation of triple-negative breast cancer through metabolic reprogramming

Treatment of patients with triple-negative breast cancer (TNBC) has been challenging due to the absence of well-defined molecular targets and the highly invasive and proliferative nature of TNBC cells. Current treatments against TNBC have shown little promise due to high recurrence rate in patients. Consequently, there is a pressing need for novel and efficacious therapies against TNBC. Here, we report the discovery of a novel small molecule inhibitor (NSC33353) with potent anti-tumor activity against TNBC cells. The anti-proliferative effects of this small molecule inhibitor were determined using 2D and 3D cell proliferation assays. We found that NSC33353 significantly reduces the proliferation of TNBC cells in these assays. Using proteomics, next generation sequencing (NGS), and gene enrichment analysis, we investigated global regulatory pathways affected by this compound in TNBC cells. Proteomics data indicate a significant metabolic reprograming affecting both glycolytic enzymes and energy generation through oxidative phosphorylation. Subsequently, using metabolic (Seahorse) and enzymatic assays, we validated our proteomics and NGS analysis findings. Finally, we showed the inhibitory and anti-tumor effects of this small molecule in vitro and confirmed its inhibitory activity in vivo. Doxorubicin is one of the most effective agents in the treatment of TNBC and resistance to this drug has been a major problem. We show that the combination of NSC33353 and doxorubicin suppresses the growth of TNBC cells synergistically, suggesting that NSC33353 enhances TNBC sensitivity to doxorubicin. In summary, our data indicate that the small molecule inhibitor, NSC33353, exhibits anti-tumor activity in TNBC cells, and works in a synergistic fashion with a well-known chemotherapeutic agent.

Computational quantification and characterization of independently evolving cellular subpopulations within tumors is critical to inhibit anti-cancer therapy resistance

BACKGROUND

Drug resistance continues to be a major limiting factor across diverse anti-cancer therapies. Contributing to the complexity of this challenge is cancer plasticity, in which one cancer subtype switches to another in response to treatment, for example, triple-negative breast cancer (TNBC) to Her2-positive breast cancer. For optimal treatment outcomes, accurate tumor diagnosis and subsequent therapeutic decisions are vital. This study assessed a novel approach to characterize treatment-induced evolutionary changes of distinct tumor cell subpopulations to identify and therapeutically exploit anticancer drug resistance.

METHODS

In this research, an information-theoretic single-cell quantification strategy was developed to provide a high-resolution and individualized assessment of tumor composition for a customized treatment approach. Briefly, this single-cell quantification strategy computes cell barcodes based on at least 100,000 tumor cells from each experiment and reveals a cell-specific signaling signature (CSSS) composed of a set of ongoing processes in each cell.

RESULTS

Using these CSSS-based barcodes, distinct subpopulations evolving within the tumor in response to an outside influence, like anticancer treatments, were revealed and mapped. Barcodes were further applied to assign targeted drug combinations to each individual tumor to optimize tumor response to therapy. The strategy was validated using TNBC models and patient-derived tumors known to switch phenotypes in response to radiotherapy (RT).

CONCLUSIONS

We show that a barcode-guided targeted drug cocktail significantly enhances tumor response to RT and prevents regrowth of once-resistant tumors. The strategy presented herein shows promise in preventing cancer treatment resistance, with significant applicability in clinical use.

A state-of-the-art review on LSD1 and its inhibitors in breast cancer: Molecular mechanisms and therapeutic significance

Breast cancer (BC) is a kind of malignant cancer in women, and it has become the most diagnosed cancer worldwide since 2020. Histone methylation is a common biological epigenetic modification mediating varieties of physiological and pathological processes. Lysine-specific demethylase 1 (LSD1), a first identified histone demethylase, mediates the removal of methyl groups from histones H3K4me1/2 and H3K9me1/2 and plays a crucial role in varieties of cancer progression. It is also specifically amplified in breast cancer and contributes to BC tumorigenesis and drug resistance via both demethylase and non-demethylase manners. This review will provide insight into the overview structure of LSD1, summarize its action mechanisms in BC, describe the therapeutic potential of LSD1 inhibitors in BC, and prospect the current opportunities and challenges of targeting LSD1 for BC therapy.

Mechanisms of carcinogenic activity triggered by lysine-specific demethylase 1A

Epigenetics has emerged as a prime focus area in the field of cancer research. Lysine-specific demethylase 1A (LSD1), the first discovered histone demethylase, is mainly responsible for catalysing demethylation of histone 3 lysine 4 (H3K4) and H3K9 to activate or inhibit gene transcription. LSD1 is abnormally expressed in various cancers and participates in cancer proliferation, apoptosis, metastasis, invasion, drug resistance and other processes by interacting with regulatory factors. Therefore, it may serve as a potential therapeutic target for cancer. This review summarises the major oncogenic mechanisms mediated by LSD1 and provides a reference for developing novel and efficient anticancer strategies targeting LSD1.

Emergence of Nanotechnology as a Powerful Cavalry against Triple-Negative Breast Cancer (TNBC)

Triple-negative breast cancer (TNBC) is considered one of the un-manageable types of breast cancer, involving devoid of estrogen, progesterone, and human epidermal growth factor receptor 2 (HER 2) receptors. Due to their ability of recurrence and metastasis, the management of TNBC remains a mainstay challenge, despite the advancements in cancer therapies. Conventional chemotherapy remains the only treatment regimen against TNBC and suffers several limitations such as low bioavailability, systemic toxicity, less targetability, and multi-drug resistance. Although various targeted therapies have been introduced to manage the hardship of TNBC, they still experience certain limitations associated with the survival benefits. The current research thus aimed at developing and improving the strategies for effective therapy against TNBC. Such strategies involved the emergence of nanoparticles. Nanoparticles are designated as nanocavalries, loaded with various agents (drugs, genes, etc.) to battle the progression and metastasis of TNBC along with overcoming the limitations experienced by conventional chemotherapy and targeted therapy. This article documents the treatment regimens of TNBC along with their efficacy towards different subtypes of TNBC, and the various nanotechnologies employed to increase the therapeutic outcome of FDA-approved drug regimens.

TdIF1-LSD1 Axis Regulates Epithelial-Mesenchymal Transition and Metastasis via Histone Demethylation of E-Cadherin Promoter in Lung Cancer

We have previously found that TdT-interacting factor 1 (TdIF1) is a potential oncogene expressed in non-small cell lung cancer (NSCLC) and is associated with poor prognosis. However, its exact mechanism is still unclear. The lysine-specific demethylase 1 (LSD1) is a crucial mediator of the epithelial-mesenchymal transition (EMT), an important process triggered during cancer metastasis. Here, we confirm that TdIF1 is highly expressed in NSCLC and related to lymph node metastasis through The Cancer Genome Atlas (TCGA) analysis of clinical samples. Silencing TdIF1 can regulate the expression of EMT-related factors and impair the migration and invasion ability of cancer cells in vitro. An analysis of tumor xenografts in nude mice confirmed that silencing TdIF1 inhibits tumor growth. Furthermore, we determined the interaction between TdIF1 and LSD1 using immunoprecipitation. Chromatin immunoprecipitation (ChIP) revealed that TdIF1 was enriched in the E-cadherin promoter region. The knockdown of TdIF1 repressed the enrichment of LSD1 at the E-cadherin promoter region, thereby regulating the level of promoter histone methylation and modulating E-cadherin transcription activity, ultimately leading to changes in EMT factors and cancer cell migration and invasion ability. The LSD1 inhibitor and TdIF1 knockdown combination showed a synergistic effect in inhibiting the growth, migration, and invasion of NSCLC cells. Taken together, this is the first demonstration that TdIF1 regulates E-cadherin transcription by recruiting LSD1 to the promoter region, thereby promoting EMT and tumor metastasis and highlighting the potential of TdIF1 as a therapeutic target for NSCLC.

Targeting Histone Modifications in Breast Cancer: A Precise Weapon on the Way

Histone modifications (HMs) contribute to maintaining genomic stability, transcription, DNA repair, and modulating chromatin in cancer cells. Furthermore, HMs are dynamic and reversible processes that involve interactions between numerous enzymes and molecular components. Aberrant HMs are strongly associated with tumorigenesis and progression of breast cancer (BC), although the specific mechanisms are not completely understood. Moreover, there is no comprehensive overview of abnormal HMs in BC, and BC therapies that target HMs are still in their infancy. Therefore, this review summarizes the existing evidence regarding HMs that are involved in BC and the potential mechanisms that are related to aberrant HMs. Moreover, this review examines the currently available agents and approved drugs that have been tested in pre-clinical and clinical studies to evaluate their effects on HMs. Finally, this review covers the barriers to the clinical application of therapies that target HMs, and possible strategies that could help overcome these barriers and accelerate the use of these therapies to cure patients.

Metastasis Prevention: Focus on Metastatic Circulating Tumor Cells

Metastasis is the main cause of cancer death. Metastatic foci are derived from tumor cells that detach from the primary tumor and then enter the circulation. Circulating tumor cells (CTCs) are generally associated with a high probability of distant metastasis and a negative prognosis. Most CTCs die in the bloodstream, and only a few cells form metastases. Such metastatic CTCs have a stem-like and hybrid epithelial-mesenchymal phenotype, can avoid immune surveillance, and show increased therapy resistance. Targeting metastatic CTCs and their progenitors in primary tumors and their descendants, particularly disseminated tumor cells, represents an attractive strategy for metastasis prevention. However, current therapeutic strategies mainly target the primary tumor and only indirectly affect metastasis-initiating cells. Here, we consider potential methods for preventing metastasis based on targeting molecular and cellular features of metastatic CTCs, including CTC clusters. Also, we emphasize current knowledge gaps in CTC biology that should be addressed to develop highly effective therapeutics and strategies for metastasis suppression.

The Anticancer Effects of FDI-6, a FOXM1 Inhibitor, on Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) presents an important clinical challenge, as it does not respond to endocrine therapies or other available targeting agents. FOXM1, an oncogenic transcriptional factor, has reported to be upregulated and associated with poor clinical outcomes in TNBC patients. In this study, we investigated the anti-cancer effects of FDI-6, a FOXM1 inhibitor, as well as its molecular mechanisms, in TNBC cells. Two TNBC cell lines, MDA-MB-231 and HS578T, were used in this study. The anti-cancer activities of FDI-6 were evaluated using various 2D cell culture assays, including Sulforhodamine B (SRB), wound healing, and transwell invasion assays together with 3D spheroid assays, mimicking real tumour structural properties. After treatment with FDI-6, the TNBC cells displayed a significant inhibition in cell proliferation, migration, and invasion. Increased apoptosis was also observed in the treated cells. In addition, we found that FDI-6 lead to the downregulation of FOXM1 and its key oncogenic targets, including CyclinB1, Snail, and Slug. Interestingly, we also found that the FDI-6/Doxorubicin combination significantly enhanced the cytotoxicity and apoptotic properties, suggesting that FDI-6 might improve chemotherapy treatment efficacy and reduce unwanted side effects. Altogether, FDI-6 exhibited promising anti-tumour activities and could be developed as a newly effective treatment for TNBC.

Roles of lysine-specific demethylase 1 (LSD1) in homeostasis and diseases

Lysine-specific demethylase 1 (LSD1) targets mono- or di-methylated histone H3K4 and H3K9 as well as non-histone substrates and functions in the regulation of gene expression as a transcriptional repressor or activator. This enzyme plays a pivotal role in various physiological processes, including development, differentiation, inflammation, thermogenesis, neuronal and cerebral physiology, and the maintenance of stemness in stem cells. LSD1 also participates in pathological processes, including cancer as the most representative disease. It promotes oncogenesis by facilitating the survival of cancer cells and by generating a pro-cancer microenvironment. In this review, we discuss the role of LSD1 in several aspects of cancer, such as hypoxia, epithelial-to-mesenchymal transition, stemness versus differentiation of cancer stem cells, as well as anti-tumor immunity. Additionally, the current understanding of the involvement of LSD1 in various other pathological processes is discussed.

A functional LSD1 coregulator screen reveals a novel transcriptional regulatory cascade connecting R-loop homeostasis with epigenetic regulation

The lysine specific demethylase 1 (LSD1) plays a pivotal role in cellular differentiation by regulating the expression of key developmental genes in concert with different coregulatory proteins. This process is impaired in different cancer types and incompletely understood. To comprehensively identify functional coregulators of LSD1, we established a novel tractable fluorescent reporter system to monitor LSD1 activity in living cells. Combining this reporter system with a state-of-the-art multiplexed RNAi screen, we identify the DEAD-box helicase 19A (DDX19A) as a novel coregulator and demonstrate that suppression of Ddx19a results in an increase of R-loops and reduced LSD1-mediated gene silencing. We further show that DDX19A binds to tri-methylated lysine 27 of histone 3 (H3K27me3) and it regulates gene expression through the removal of transcription promoting R-loops. Our results uncover a novel transcriptional regulatory cascade where the downregulation of genes is dependent on the LSD1 mediated demethylation of histone H3 lysine 4 (H3K4). This allows the polycomb repressive complex 2 (PRC2) to methylate H3K27, which serves as a binding site for DDX19A. Finally, the binding of DDX19A leads to the efficient removal of R-loops at active promoters, which further de-represses LSD1 and PRC2, establishing a positive feedback loop leading to a robust repression of the target gene.

miR-770-5p regulates EMT and invasion in TNBC cells by targeting DNMT3A

MicroRNAs (miRNAs) are shown to regulate various processes in cancer like motility and invasion that are key features of the metastatic triple negative breast cancer (TNBCs). Epithelial-mesenchymal transition (EMT) is one of the well-defined cellular transitioning processes characterized with reduced E-cadherin expression and increased mesenchymal molecules such as Vimentin or Snail thereby gives the cells mobility and invasive character. Aberrant DNA methylation by DNA methyltransferases (DNMTs) plays an important role in carcinogenesis. It is well known that DNMTs are required for transcriptional silencing of tumor-associated genes. DNMT3A-induced promoter hypermethylation of E-cadherin has also been known to improve cancer metastasis. Our results indicated that miR-770-5p could downregulate Vimentin and Snail expression levels, while increasing or restoring the expression of E-Cadherin hence, leading to inhibition of EMT phenotypes along with motility and invasion. Specifically, we showed that overexpression of miR-770-5p restored the expression of E-Cadherin in MDA-MB-231 cells via directly targeting DNMT3A. We also observed the change in the spindled shapes showing the loss of mesenchymal characteristics and gain of epithelial phenotype in miR-770-5p overexpressing cells. When considered together, our results show that miR-770-5p could effectively inhibit invasion potential driven by EMT.

LSD1 as a Biomarker and the Outcome of Its Inhibitors in the Clinical Trial: The Therapy Opportunity in Tumor

Tumors are the foremost cause of death worldwide. As a result of that, there has been a significant enhancement in the investigation, treatment methods, and good maintenance practices on cancer. However, the sensitivity and specificity of a lot of tumor biomarkers are not adequate. Hence, it is of inordinate significance to ascertain novel biomarkers to forecast the prognosis and therapy targets for tumors. This review characterized LSD1 as a biomarker in different tumors. LSD1 inhibitors in clinical trials were also discussed. The recent pattern advocates that LSD1 is engaged at sauce chromatin zones linking with complexes of multi-protein having an exact DNA-binding transcription factor, establishing LSD1 as a favorable epigenetic target, and also gives a large selection of therapeutic targets to treat different tumors. This review sturdily backing the oncogenic probable of LSD1 in different tumors indicated that LSD1 levels can be used to monitor and identify different tumors and can be a useful biomarker of progression and fair diagnosis in tumor patients. The clinical trials showed that inhibitors of LSD1 have growing evidence of clinical efficacy which is very encouraging and promising. However, for some of the inhibitors such as GSK2879552, though selective, potent, and effective, its disease control was poor as the rate of adverse events (AEs) was high in tumor patients causing clinical trial termination, and continuation could not be supported by the risk-benefit profile. Therefore, we propose that, to attain excellent clinical results of inhibitors of LSD1, much attention is required in designing appropriate dosing regimens, developing in-depth in vitro/in vivo mechanistic works of LSD1 inhibitors, and developing inhibitors of LSD1 that are reversible, safe, potent, and selective which may offer safer profiles.

Collagen type VIII alpha 2 chain (COL8A2), an important component of the basement membrane of the corneal endothelium, facilitates the malignant development of glioblastoma cells via inducing EMT

Glioblastoma (GBM) is one of the most lethal tumor of all human cancers. Due to its poor response to chemotherapy and radiotherapy as well as its high rate of recurrence after treatment, the treatment is still undesired. The identification of potential related genes and bio-markers in the development of GBM could provide some new targets for the treatment of GBM. Our purpose in this study was to evaluate the mission of COL8A2 in GBM. Combined with TCGA, Oncomine databases, CGGA, GEPIA website and qRT-PCR analyses, we found that COL8A2 was up-regulated both in GBM tissues and cells compared to the controls. Moreover, the high COL8A2 expression was associated with the shorter overall survival of patients with GBM. The expression of COL8A2 was also positively correlated with metastasis-associated genes including vimentin, snail, slug, MMP2 and MMP7 according to GEPIA website. Knockdown of COL8A2 could suppress the cell proliferation, cell migration and invasion, whereas the overexpression of COL8A2 significantly expedited these processes. What's more, the outcome of western blot analysis manifested that COL8A2 could induced the expression of vimentin, snail, slug, MMP2 and MMP7. Taken together, COL8A2 activated cell proliferation, cell migration and invasion via raising the relative expression of EMT-related proteins in GBM. Therefore, our investigation suggests the oncogenic role of COL8A2 in GBM and provides a potential application of COL8A2 for GBM therapy.

A Novel Inhibitor of Carbonic Anhydrases Prevents Hypoxia-Induced TNBC Cell Plasticity

Cell plasticity is the ability that cells have to modify their phenotype, adapting to the environment. Cancer progression is under the strict control of the the tumor microenvironment that strongly determines its success by regulating the behavioral changes of tumor cells. The cross-talk between cancer and stromal cells and the interactions with the extracellular matrix, hypoxia and acidosis contribute to trigger a new tumor cell identity and to enhance tumor heterogeneity and metastatic spread. In highly aggressive triple-negative breast cancer, tumor cells show a significant capability to change their phenotype under the pressure of the hypoxic microenvironment. In this study, we investigated whether targeting the hypoxia-induced protein carbonic anhydrase IX (CA IX) could reduce triple-negative breast cancer (TNBC) cell phenotypic switching involved in processes associated with poor prognosis such as vascular mimicry (VM) and cancer stem cells (CSCs). The treatment of two TNBC cell lines (BT-549 and MDA-MB-231) with a specific CA IX siRNA or with a novel inhibitor of carbonic anhydrases (RC44) severely impaired their ability to form a vascular-like network and mammospheres and reduced their metastatic potential. In addition, the RC44 inhibitor was able to hamper the signal pathways involved in triggering VM and CSC formation. These results demonstrate that targeting hypoxia-induced cell plasticity through CA IX inhibition could be a new opportunity to selectively reduce VM and CSCs, thus improving the efficiency of existing therapies in TNBC.

Knockdown of CSNK2ß suppresses MDA-MB231 cell growth, induces apoptosis, inhibits migration and invasion

Breast cancer is the most common cancer among women worldwide. Among different types of breast cancer known, treatment of triple-negative breast cancer is a major challenge because of its aggressiveness and poor prognosis; thus, identification of specific drivers is required for targeted therapies of breast cancer malignancy. Protein Casein Kinase (CSNK) is a serine/threonine kinase that exists as a tetrameric complex consisting of two catalytic (α and /or α') and two regulatory β subunits. CSNK2β can also function independently without catalytic subunits and exist as a distinct population in cells. This study aims to elucidate the role of Casein Kinase 2β (CSNK2β) gene in cell proliferation, cell cycle, migration and apoptosis of triple-negative breast cancer MDA-MB-231 cells. The silencing of CSNK2β in MDA-MB-231 cells resulted in decreased cell viability and colony formation. Cell cycle analysis showed a significant arrest of cells in G2M phase. Hoechst and CM-H2DCFDA staining showed nuclear condensation and augmented intracellular reactive oxygen species (ROS) production. Furthermore, silencing of CSNK2β in MDA-MB-231 cells modulated the apoptotic machinery- BAX, Bcl-xL, and caspase 3; autophagy machinery-Beclin-1 and LC3-1; and inhibited the vital markers (p-ERK, c-Myc, NF-κB, E2F1, PCNA, p38-α) associated with cell proliferation and DNA replication pathways. In addition, knockdown of CSNK2β also affected the migration potential of MDA-MB-231, as observed in the wound healing and transwell migration assays. Altogether, the study suggests that CSNK2β silencing may offer future therapeutic target in triple-negative breast cancer.

The histopathological and molecular features of breast carcinoma with tumour budding-a systematic review and meta-analysis

PURPOSE

Tumour budding (TB) is an adverse histological feature in many epithelial cancers. It is thought to represent epithelial-mesenchymal transition, a key step in the metastatic process. The significance of TB in breast carcinoma (BC) remains unclear. The aim of this study is to investigate the relationship between TB and other histological and molecular features of BC.

METHODS

A systematic search was performed to identify studies that compared features of BC based on the presence or absence of high-grade TB. Dichotomous variables were pooled as odds ratios (OR) using the Der Simonian-Laird method. Quality assessment of the included studies was performed using the Newcastle-Ottawa scale (NOS).

RESULTS

Seven studies with a total of 1040 patients (high-grade TB n = 519, 49.9%; low-grade/absent TB n = 521, 50.1%) were included. A moderate to high risk of bias was noted. The median NOS was 7 (range 6-8). High-grade TB was significantly associated with lymph node metastasis (OR 2.32, 95% c.i. 1.77 to 3.03, P < 0.001) and lymphovascular invasion (OR 3.08, 95% c.i. 2.13 to 4.47, P < 0.001). With regard to molecular subtypes, there was an increased likelihood of high-grade TB in oestrogen (OR 1.66, 95% c.i. 1.21 to 2.29, P = 0.002) and progesterone receptor-positive (OR 1.48, 95% c.i. 1.09 to 2.02, P = 0.01) tumours. In contrast, triple-negative breast cancer had a reduced incidence of high-grade TB (OR 0.46, 95% c.i. 0.30 to 0.72, P = 0.0006).

CONCLUSION

High-grade TB is enriched in hormone receptor-positive BC and is associated with known adverse prognostic variables. TB may offer new insights into the metastatic process of BC.

Differential Impact of Calcitriol and Its Analogs on Tumor Stroma in Young and Aged Ovariectomized Mice Bearing 4T1 Mammary Gland Cancer

(1) Background: Vitamin D compounds (VDC) are extensively studied in the field of anticancer properties, including breast cancer. Previously, we showed that calcitriol and its analogs (PRI-2191 and PRI-2205) stimulate metastasis in 4T1 murine mammary gland cancer models in young mice, whereas the reverse effect was observed in aged ovariectomized (OVX) mice; (2) Methods: We determined the phenotype of monocytes/macrophages using FACS and examined the expression of selected genes and proteins by Real-Time PCR and ELISA; (3) Results: Activities of VDC are accompanied by an increase in the percentage of Ly6Clow anti-inflammatory monocytes in the spleen of young and a decrease in aged OVX mice. Treatment of young mice with VDC resulted in an increase of CCL2 plasma and tumor concentration and Arg1 in tumor. In later stage of tumor progression the expression of genes related to metastasis in lung tissue was decreased or increased, in old OVX or young mice, respectively; (4) Conclusions: Pro- or anti-metastatic effects of calcitriol and its analogs in young or aged OVX mice, respectively, can be attributed to the differences in the effects of VDC on the tumor microenvironment, as a consequence of differences in the immunity status of young and aged mice.

CBP-mediated Slug acetylation stabilizes Slug and promotes EMT and migration of breast cancer cells

Slug, a member of the Snail family of transcriptional repressors, plays a key role in cancer progression, cellular plasticity, and epithelial to mesenchymal transition (EMT). Slug is a fast-turnover protein and its stability is controlled by post-translational modifications. Here, we identified that Slug is acetylated by acetyltransferase CREB-binding protein (CBP) in breast cancer cells. CBP directly interacts with the C-terminal domain of Slug through its catalytic histone acetyltransferase (HAT) domain, leading to acetylation of Slug at lysines 166 and 211. Analysis with acetylation-specific antibodies revealed that Slug is highly acetylated in metastatic breast cancer cells. Notably, Slug acetylation, mediated by CBP at lysines 166 and 211, doubles its half-life and increases its stability. Further, acetylated Slug downregulates the expression of E-cadherin, the epithelial marker, and upregulates the expression of N-cadherin and vimentin, thereby promoting breast cancer cell migration. In conclusion, the present study demonstrates that CBP-mediated Slug acetylation increases its stability, promoting EMT and migration of breast cancer cells.

Slug and E-Cadherin: Stealth Accomplices?

During physiological epithelial-mesenchymal transition (EMT), which is important for embryogenesis and wound healing, epithelial cells activate a program to remodel their structure and achieve a mesenchymal fate. In cancer cells, EMT confers increased invasiveness and tumor-initiating capacity, which contribute to metastasis and resistance to therapeutics. However, cellular plasticity that navigates between epithelial and mesenchymal states and maintenance of a hybrid or partial E/M phenotype appears to be even more important for cancer progression. Besides other core EMT transcription factors, the well-characterized Snail-family proteins Snail (SNAI1) and Slug (SNAI2) play important roles in both physiological and pathological EMT. Often mentioned in unison, they do, however, differ in their functions in many scenarios. Indeed, Slug expression does not always correlate with complete EMT or loss of E-cadherin (CDH1). For example, Slug plays important roles in mammary epithelial cell progenitor cell lineage commitment and differentiation, DNA damage responses, hematopoietic stem cell self-renewal, and in pathologies such as pulmonary fibrosis and atherosclerosis. In this Perspective, we highlight Slug functions in mammary epithelial cells and breast cancer as a “non-EMT factor” in basal epithelial cells and stem cells with focus reports that demonstrate co-expression of Slug and E-cadherin. We speculate that Slug and E-cadherin may cooperate in normal mammary gland and breast cancer/stem cells and advocate for functional assessment of such Slug⁺/E-cadherin^low/+ (SNAI2⁺/CDH1^low/+) “basal-like epithelial” cells. Thus, Slug may be regarded as less of an EMT factor than driver of the basal epithelial cell phenotype.

LSD1: a viable therapeutic target in cutaneous squamous cell carcinoma?

INTRODUCTION

Cutaneous squamous cell carcinoma (cSCC) is the second most frequent cancer; it can be locally invasive and metastatic. cSCC is an immense clinical and economic problem given its sheer incidence and potential morbidity and mortality, particularly in the elderly and immunocompromised. Epigenetics has emerged as one of the most exciting areas of human biology, impacting virtually all areas of cellular physiology. Inhibition of an epigenetic enzyme is a potential treatment of cSCC.

AREAS COVERED

We provide an overview of the development of inhibitors targeting the lysine demethylase, LSD1 (KDM1A), the first histone demethylase discovered. We summarize current treatment modalities for cSCC and provide a rationale for why epigenome-targeting therapies, and particularly LSD1 inhibitors, may be a novel and effective approach for treating pre-malignant and malignant cSCCs. A search was conducted in PubMed utilizing the combination of 'LSD1' with keywords such as 'epidermis,' 'squamous cell carcinoma,' or 'skin.' Relevant papers from 2000 to 2020 were reviewed.

EXPERT OPINION

Given the ability of LSD1 inhibitors to promote epidermal differentiation and enhance anti-tumor immune responses, LSD1 inhibitors may offer a highly effective therapeutic approach for the prevention and treatment of these ubiquitous cancers.

Epi-drugs as triple-negative breast cancer treatment

Triple-negative breast cancer (TNBC) types with poor prognosis are due to the absence of estrogen receptors, progesterone receptors and HEGFR-2. The lack of suitable therapy for TNBC has led the research community to turn toward epigenetic regulation and its protagonists that can modulate certain oncogenes and tumor suppressors. This has opened an important new field of therapy using epi-drugs, in preclinical and clinical trials. The epi-drugs are natural or synthetic molecules capable of inhibiting or modulating the activity of epigenetic proteins such as DNA methyltransferases, modulating the expression of interferon microRNAs, as well as histone methyltransferases, demethylases, acetyltransferases and deacetylases. This review investigated the epi-drugs used in the treatment of TNBC.

Pro-metastatic functions of Notch signaling is mediated by CYR61 in breast cells

Metastasis is the main cause of cancer related deaths, and unfolding the molecular mechanisms underlying metastatic progression is critical for the development of novel therapeutic approaches. Notch is one of the key signaling pathways involved in breast tumorigenesis and metastasis. Notch activation induces pro-metastatic processes such as migration, invasion and epithelial to mesenchymal transition (EMT). However, molecular mediators working downstream of Notch in these processes are not fully elucidated. CYR61 is a secreted protein implicated in metastasis, and its inhibition by a monoclonal antibody suppresses metastasis in xenograft breast tumors, indicating the clinical importance of CYR61 targeting. Here, we aimed to investigate whether CYR61 works downstream of Notch in inducing pro-metastatic phenotypes in breast cells. We showed that CYR61 expression is positively regulated by Notch activity in breast cells. Notch1-induced migration, invasion and anchorage independent growth of a normal breast cell line, MCF10A, were abrogated by CYR61 silencing. Furthermore, upregulation of core EMT markers upon Notch1-activation was impaired in the absence of CYR61. However, reduced migration and invasion of highly metastatic cell line, MDA MB 231, cells upon Notch inhibition was not dependent on CYR61 downregulation. In conclusion, we showed that in normal breast cell line MCF10A, CYR61 is a mediator of Notch1-induced pro-metastatic phenotypes partly via induction of EMT. Our results imply CYR61 as a prominent therapeutic candidate for a subpopulation of breast tumors with high Notch activity.

SNAI1 interacts with HDAC1 to control TGF‑β2‑induced epithelial‑mesenchymal transition in human lens epithelial cells

The opacity of the lens capsule after cataract surgery is caused by epithelial‑to‑mesenchymal transition (EMT) of lens epithelial cells. Snail family transcriptional repressor 1 (SNAI1) is a transcriptional repressor that recruits multiple chromatin enzymes including lysine‑specific histone demethylase 1A, histone deacetylase (HDAC) 1/2, polycomb repressive complex 2, euchromatic histone lysine methyltransferase 2 and suppressor of variegation 3‑9 homolog 1 to the E‑cadherin promoter, thereby suppressing E‑cadherin expression. However, the functional relationship between SNAI1 and HDAC in the induction of EMT in human lens epithelial cells (HLECs) is still unclear. Therefore, the objective of the present study was to explore the possible functional relationship between SNAI1 and HDAC1 in the induction of EMT in HLECs. In the present study, SNAI1 was found to be increased in HLECs during transforming growth factor‑β2 (TGF‑β2)‑induced EMT. Knockdown of SNAI1 by siRNA reversed TGF‑β2‑induced downregulation of E‑cadherin and upregulation of α‑Smooth Muscle Actin. Furthermore, SNAI1 was found to be associated with HDAC1 in the E‑cadherin promoter in TGF‑β2‑treated HLECs. Inhibition of HDAC by trichostatin A and suberoylanilide hydroxamic acid could prevent TGF‑β2‑induced EMT in HLECs. Collectively, SNAI1 interacted with HDAC1 to repress E‑cadherin in the TGF‑β2‑induced EMT in HLECs, suggesting that HDAC inhibitors may have potential therapeutic value for the prevention of EMT in HLECs.

LSD1/KDM1A, a Gate-Keeper of Cancer Stemness and a Promising Therapeutic Target

A new exciting area in cancer research is the study of cancer stem cells (CSCs) and the translational implications for putative epigenetic therapies targeted against them. Accumulating evidence of the effects of epigenetic modulating agents has revealed their dramatic consequences on cellular reprogramming and, particularly, reversing cancer stemness characteristics, such as self-renewal and chemoresistance. Lysine specific demethylase 1 (LSD1/KDM1A) plays a well-established role in the normal hematopoietic and neuronal stem cells. Overexpression of LSD1 has been documented in a variety of cancers, where the enzyme is, usually, associated with the more aggressive types of the disease. Interestingly, recent studies have implicated LSD1 in the regulation of the pool of CSCs in different leukemias and solid tumors. However, the precise mechanisms that LSD1 uses to mediate its effects on cancer stemness are largely unknown. Herein, we review the literature on LSD1's role in normal and cancer stem cells, highlighting the analogies of its mode of action in the two biological settings. Given its potential as a pharmacological target, we, also, discuss current advances in the design of novel therapeutic regimes in cancer that incorporate LSD1 inhibitors, as well as their future perspectives.

Identification of upstream miRNAs of SNAI2 and their influence on the metastasis of gastrointestinal stromal tumors

Background

SNAI2, a member of the snail zinc finger protein family, plays an important role in the metastasis of several types of carcinoma.

Objective

This study aims to investigate the upstream miRNAs of SNAI2 and their influence on the metastasis of gastrointestinal stromal tumors (GISTs).

Methods

The expression levels of SNAI2, CDH1, and CDH2 in GISTs were determined by immunohistochemistry, and the correlations with their clinicopathologic characteristics were analyzed. Subsequently, the miRNAs involved in regulating SNAI2 expression were predicted by bioinformatics technique, screened by miRNA microarray tests, and verified by real-time PCR, dual luciferase reporter assay, and invasion assay. The influence of SNAI2 and miRNAs on the invasive ability of the GIST cells and the related mechanism were detected.

Outcomes

SNAI2 expression significantly increased and CDH1 expression markedly decreased in the cases of GISTs with distant metastasis. Silencing of the SNAI2 gene impaired the invasiveness of GIST cells in vitro. MiR-200b-3p, miR-30c-1-3P, and miR-363-3P were verified as the upstream metastasis-associated miRNAs of SNAI2 in GISTs by miRNA microarray, real-time PCR, dual luciferase reporter assay, and invasion assay. They bound to the 3′-UTR of SNAI2, downregulated SNAI2 expression, and inhibited the invasiveness of GIST cells. SNAI2 targetedly bound to the promoter of the CDH1 gene, downregulated the expression of CDH1, and contributed to the metastasis of GISTs.

Conclusion

SNAI2 and CDH1 correlated with the metastasis of GISTs, and silencing of the SNAI2 gene impaired the invasiveness of GIST cells. MiR-200b-3p, miR-30c-1-3P, and miR-363-3P contribute to the metastasis of GISTs in vitro by mediating the SNAI2/CDH1 axis. SNAI2 may be a potential target for the treatment of GISTs in the future.

STAT3 Targets ERR-α to Promote Epithelial-Mesenchymal Transition, Migration, and Invasion in Triple-Negative Breast Cancer Cells

STAT3 is constitutively activated in many malignant tumor types and plays an important role in multiple aspects of cancer aggressiveness. In this study, we found that estrogen-related receptor α (ERR-α) correlating with STAT3 was highly expressed in triple-negative breast cancer (TNBC) cell lines and tissues, which was associated with both the pathologic stage and prognosis of patients with TNBC. In vitro studies showed that ERR-α promoted TNBC cell migration and invasion, which was regulated by STAT3. Phosphorylated STAT3 (p-STAT3, Tyr 705) could bind to the promotor of ERR-α, and activate its transcription, which was suggested by luciferase assay and chromatin immunoprecipitation assay. We also found that ERR-α was the key target gene regulated by STAT3 in promoting epithelial-mesenchymal transition (EMT), migration, and invasion. ERR-α upregulated the expression of ZEB1, N-cadherin, and vimentin while downregulated the expression of E-cadherin. Furthermore, in vivo studies showed that ERR-α could increase the metastasis ability of TNBC. Our finding demonstrated that ERR-α was a direct regulatory gene target of p-STAT3, which was enriched for processes involving invasion and metastasis in TNBC and provided insight into TNBC pathogenesis, as well as a potential therapeutic option against TNBC metastasis. IMPLICATIONS: Our research first showed that p-STAT3 (Tyr 705) could bind to the promotor region of ERR-α and promote EMT in TNBC by ZEB1 pathways, thus providing a potential clinical target for TNBC.

Phenotypic, structural, and ultrastructural analysis of triple-negative breast cancer cell lines and breast cancer stem cell subpopulation

Triple negative breast cancer (TNBC) is a highly heterogeneous disease, which influences the therapeutic response and makes difficult the discovery of effective targets. This heterogeneity is attributed to the presence of breast cancer stem cells (BCSCs), which determines resistance to chemotherapy and subsequently disease recurrence and metastasis. In this context, this work aimed to evaluate the morphological and phenotypic cellular heterogeneity of two TNBC cell lines cultured in monolayer and tumorsphere (TS) models by fluorescence and electron microscopy and flow cytometry. The BT-549 and Hs 578T analyses demonstrated large phenotypic and morphological heterogeneity between these cell lines, as well as between the cell subpopulations that compose them. BT-549 and Hs 578T are heterogeneous considering the cell surface marker CD44 and CD24 expression, characterizing BCSC mesenchymal-like cells (CD44⁺/CD24^-), epithelial cells (CD44^-/CD24⁺), hybrid cells with mesenchymal and epithelial features (CD44⁺/CD24⁺), and CD44^-/CD24^- cells. BCSC epithelial-like cells (ALDH⁺) were found in BT-549, BT-549 TS, and Hs 578T TS; however, only BT-549 TS showed a high ALDH activity. Ultrastructural characterization showed the heterogeneity within and among BT-549 and Hs 578T in monolayer and TS models being formed by more than one cellular type. Further, the mesenchymal characteristic of these cells is demonstrated by E-cadherin absence and filopodia. It is well known that tumor cell heterogeneity can influence survival, therapy responses, and the rate of tumor growth. Thus, molecular understanding of this heterogeneity is essential for the identification of potential therapeutic options and vulnerabilities of oncological patients.

LSD1 regulates Notch and PI3K/Akt/mTOR pathways through binding the promoter regions of Notch target genes in esophageal squamous cell carcinoma

Background: The aberrant activation of Lysine-specific demethylase 1(LSD1), Notch and PI3K/Akt/mTOR signaling pathways were frequently happened in many cancers, including esophageal squamous cell carcinoma (ESCC). However, the regulatory relationship between LSD1 and Notch as well as PI3K/Akt/mTOR pathways is still unclear. Purpose: This study aimed to explore the regulatory effects and mechanisms of LSD1 on Notch and PI3K/Akt/mTOR pathway in ESCC. Results: Firstly, we demonstrated that LSD1 and proteins in Notch and PI3K/Akt/mTOR pathway were expressed in ESCC cells. Secondly, inhibition of LSD1 by tranylcypromine (TCP) or shRNA could decrease the expressions of related proteins in Notch and PI3K/Akt/mTOR signaling pathways in ESCC cells. Finally, we found that LSD1 could bind to the promoter regions of Notch3, Hes1 and CR2, and the combinations between them were reduced by TCP in ESCC. Conclusion: Summarily, this study indicated that LSD1 might positively regulate Notch and PI3K/Akt/mTOR pathways through binding the promoter regions of related genes in Notch pathway in ESCC.

Nanosized functional miRNA liposomes and application in the treatment of TNBC by silencing Slug gene

Background: Neo-adjuvant chemotherapy is an effective strategy for improving treatment of breast cancers. However, the efficacy of this treatment strategy is limited for treatment of triple negative breast cancer (TNBC). Gene therapy may be a more effective strategy for improving the prognosis of TNBC.

Methods: A novel 25 nucleotide sense strand of miRNA was designed to treat TNBC by silencing the Slug gene, and encapsulated into DSPE-PEG₂₀₀₀-tLyp-1 peptide-modified functional liposomes. The efficacy of miRNA liposomes was evaluated on invasive TNBC cells and TNBC cancer-bearing nude mice. Furthermore, functional vinorelbine liposomes were constructed to investigate the anticancer effects of combined treatment.

Results: The functional miRNA liposomes had a round shape and were nanosized (120 nm). Functional miRNA liposomes were effectively captured by TNBC cells in vitro and were target to mitochondria. Treatment with functional liposomes silenced the expression of Slug and Slug protein, inhibited the TGF-β1/Smad pathway, and inhibited invasiveness and growth of TNBC cells. In TNBC cancer-bearing mice, functional miRNA liposomes exerted a stronger anticancer effect than functional vinorelbine liposomes, and combination therapy with these two formulations resulted in nearly complete inhibition of tumor growth. Preliminary safety evaluations indicated that the functional miRNA liposomes did not affect body weight or cause damage to any major organs. Furthermore, the functional liposomes significantly increased the half-life of the drug in the blood of cancer-bearing nude mice, and increased drug accumulation in breast cancer tissues.

Conclusion: In this study, we constructed novel functional miRNA liposomes. These liposomes silenced Slug expression and inhibited the TGF-β1/Smad pathway in TNBC cells, and enhanced anticancer efficacy in mice using combined chemotherapy. Hence, the present study demonstrated a promising strategy for gene therapy of invasive breast cancer.

Upregulation of LSD1 promotes migration and invasion in gastric cancer through facilitating EMT

Background

Gastric cancer (GC) is a common malignant tumor of the digestive system. In addition, GC metastasis is an extremely complicated process. A previous study has found that lysine-specific demethylase 1 (LSD1) is abnormal expression in a variety of cancers and its overexpression correlates with aggressive disease and poor outcome.

Methods

qRT-PCR and Western blot assays were used to assess the expression of LSD1 in GC tissue samples and cell lines. Colony formation assay, CCK-8 assay, scratch-wound assay and transwell invasion, were performed to determine the effect of LSD1 on cell proliferation and migration as well as invasion in GC.

Results

Our results show that LSD1 was up-regulated in GC tumor tissues and cell lines, and high expression level of LSD1 was found to be positively correlated with tumor size, lymph node metastasis and pathological grade. Moreover, LSD1 promoted cell proliferation, migration and invasion of GC. In addition, LSD1 regulated E-cadherin expression through demethylating H3K4me2, thereby promoting EMT in GC.

Conclusion

Our work indicated that LSD1 may be used as a potential target of gastric cancer.

Epithelial cell adhesion molecule and epithelial-mesenchymal transition are associated with vasculogenic mimicry, poor prognosis, and metastasis of triple negative breast cancer

Triple-negative breast cancer (TNBC) is associated with epithelial-mesenchymal transition (EMT) and the phenotype of breast cancer stem cells (CSCs). Vasculogenic mimicry (VM) is a novel pattern of tumor blood supply and associated with aggression and metastasis of TNBC. Previous studies have shown that both CSCs and EMT are associated with VM, although the underlying mechanism is yet unclear. The present study aimed to analyze the immunohistochemical (IHC) expression of CSC marker, epithelial cell adhesion molecule (EpCAM), EMT-related markers, including transcription factors (TFs) (Slug, Twist1, and ZEB1), and EMT markers (E-cadherin and vimentin) in 137 TNBC. The expression of these markers was correlated to the clinicopathological features and VM channels of the tumors, including patient overall survival (OS) and disease-free survival (DFS). Furthermore, the expression of EpCAM and EMT-related markers showed a positive correlation with distant metastasis and lymph node metastasis (P < 0.05). A significant association was noted between VM and histological grade (P = 0.007). Moreover, VM showed a significant positive correlation with EpCAM, EMT-associated TFs, and VE-cadherin expression in TNBC. Furthermore, binary logistic analysis showed that VM expression was significantly correlated with lymph node metastasis and distant metastasis (P < 0.05). In survival analysis, the overexpression of EpCAM and ZEB1 predicted a poor prognosis with respect to OS and DFS. In addition, the presence of VM was significantly associated with poor OS and DFS. Multivariate Cox regression analysis revealed that VM expression is an independent prognostic factor for TNBC patients. In summary, VM was confirmed as a potential biomarker for TNBC associated with poor clinical outcomes and tumor metastasis. This study also suggested that EpCAM protein might be involved in VM formation by EMT in TNBC.

New Insights into the Implication of Epigenetic Alterations in the EMT of Triple Negative Breast Cancer

Breast cancer is the most common cancer and leading cause of cancer death among women worldwide, encompassing a wide heterogeneity of subtypes with different clinical features. During the last two decades, the use of targeted therapies has emerged in clinical research in order to increase treatment efficiency, improve prognosis and reduce recurrence. However, the triple negative breast cancer (TNBC) subtype remains a clinical challenge, with poor prognosis since no therapeutic targets have been identified. This aggressive breast cancer entity lacks expression of oestrogen receptor (ER) and progesterone receptor (PR), and it does not overexpress human epidermal growth factor receptor 2 (HER2). The major reason for TNBC poor prognosis is early therapeutic escape from conventional treatments, leading to aggressive metastatic relapse. Metastases occur after an epithelial-mesenchymal transition EMT of epithelial cells, allowing them to break free from the primary tumour site and to colonize distant organs. Cancer-associated EMT consists not only of acquired migration and invasion ability, but involves complex and comprehensive reprogramming, including changes in metabolism, expression levels and epigenetic. Recently, many studies have considered epigenetic alterations as the primary initiator of cancer development and metastasis. This review builds a picture of the epigenetic modifications implicated in the EMT of breast cancer. It focuses on TNBC and allows comparisons with other subtypes. It emphasizes the role of the main epigenetic modifications lncRNAs, miRNAs, histone and DNA- modifications in tumour invasion and appearance of metastases. These epigenetic alterations can be considered biomarkers representing potential diagnostic and prognostic factors in order to define a global metastatic signature for TNBC.

Enhancing Chemosensitivity of Breast Cancer Stem Cells by Downregulating SOX2 and ABCG2 Using Wedelolactone-encapsulated Nanoparticles

A major caveat in the treatment of breast cancer is disease recurrence after therapeutic regime at both local and distal sites. Tumor relapse is attributed to the persistence of chemoresistant cancer stem cells (CSC), which need to be obliterated along with conventional chemotherapy. Wedelolactone, a naturally occurring coumestan, demonstrates anticancer effects in different cancer cells, although with several limitations, and is mostly ineffective against CSCs. To enhance its biological activity in cancer cells and additionally target the CSCs, wedelolactone-encapsulated PLGA nanoparticles (nWdl) were formulated. Initial results indicated that nanoformulation of wedelolactone not only increased its uptake in breast cancer cells and the CSC population, it enhanced drug retention and sustained release within the cells. Enhanced drug retention was achieved by downregulation of SOX2 and ABCG2, both of which contribute to drug resistance of the CSCs. In addition, nWdl prevented epithelial-to-mesenchymal transition, suppressed cell migration and invasion, and reduced the percentage of breast cancer stem cells (BCSC) in MDA-MB-231 cells. When administered in combination with paclitaxel, which is known to be ineffective against BCSCs, nWdl sensitized the cells to the effects of paclitaxel and reduced the percentage of ALDH⁺ BCSCs and mammospheres. Furthermore, nWdl suppressed growth of solid tumors in mice and also reduced CD44⁺/CD24^-/low population. Taken together, our data imply that nWdl decreased metastatic potential of BCSCs, enhanced chemosensitivity through coordinated regulation of pluripotent and efflux genes, and thereby provides an insight into effective drug delivery specifically for obliterating BCSCs.

Liposomal borrelidin for treatment of metastatic breast cancer

Borrelidin is an inhibitor of threonyl-tRNA synthetase with both anticancer and antiangiogenic activities. Although borrelidin could be a potent drug that can treat metastatic cancer through synergistic therapeutic effects, its severe liver toxicity has limited the use for cancer therapeutics. In this study, we developed a liposomal formulation of borrelidin to treat metastatic breast cancer effectively through its combined anticancer and antiangiogenic effects while reducing the potential liver toxicity. The liposomal formulation was optimized to maximize loading stability and efficiency of lipophilic borrelidin in the liposomal membrane and its delivery efficiency to primary tumor in a mouse model of metastatic breast cancer. Liposomal borrelidin showed significant in vitro therapeutic effects on proliferation and migration of tumor cells and angiogenesis of endothelial cells. Furthermore, liposomal borrelidin exhibited superior inhibitory effects on primary tumor growth and lung metastasis in vivo compared to free borrelidin. More importantly, liposomal borrelidin did not induce any significant systemic toxicity in the mouse model after multiple injections.

Casticin inhibits breast cancer cell migration and invasion by down-regulation of PI3K/Akt signaling pathway

Casticin is one of the major active components isolated from Fructus viticis Increasing studies have revealed that casticin has potential anticancer activity in various cancer cells, but its effects on breast cancer cell migration and invasion are still not well known. Therefore, the ability of cell migration and invasion in the breast cancer MDA-MB-231 and 4T1 cells treated by casticin was investigated. The results indicated that casticin significantly inhibited cell migration and invasion in the cells exposed to 0.25 and 0.50 µM of casticin for 24 h. Casticin treatment reduced matrix metalloproteinase (MMP) 9 (MMP-9) activity and down-regulated MMP-9 mRNA and protein expression, but not MMP-2. Casticin treatment suppressed the nuclear translocation of transcription factors c-Jun and c-Fos, but not nuclear factor-κB (NF-κB), and decreased the phosphorylated level of Akt (p-Akt). Additionally, the transfection of Akt overexpression vector to MDA-MB-231 and 4T1 cells could up-regulate MMP-9 expression concomitantly with a marked increase in cell invasion, but casticin treatment reduced Akt, p-Akt, and MMP-9 protein levels and inhibited the ability of cell invasion in breast cancer cells. Additionally, casticin attenuated lung metastasis of mouse 4T1 breast cancer cells in the mice and down-regulated MMP-9 expression in the lung tissues of mice treated by casticin. These findings suggest that MMP-9 expression suppression by casticin may act through inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway, which in turn results in the inhibitory effects of casticin on cell migration and invasion in breast cancer cells. Therefore, casticin may have potential for use in the treatment of breast cancer invasion and metastasis.